url stringlengths 14 1.76k | text stringlengths 100 1.02M | metadata stringlengths 1.06k 1.1k |
|---|---|---|
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=DBSHCJ_2009_v24n1_99 | A REMARK ON ERGODICITY OF QUANTUM MARKOVIAN SEMIGROUPS
Title & Authors
A REMARK ON ERGODICITY OF QUANTUM MARKOVIAN SEMIGROUPS
Ko, Chul-Ki;
Abstract
The aim of this paper is to find the set of the fixed elements and the set of elements for which equality holds in Schwarz inequality for the KMS-symmetric Markovian semigroup $\small{\{S_t\}_{t{\geq}0}}$ given in [10]. As an application, we study some properties such as the ergodicity and the asymptotic behavior of the semigroup.
Keywords
quantum Markovian semigroups;ergodicity;
Language
English
Cited by
References
1.
O. Bratteli and D. W. Robinson, Operator algebras and quantum statistical mechanics, Springer-Verlag, New York-Heidelberg-Berlin, vol I (1979)
2.
F. Cipriani, Dirichlet forms and Markovian semigroups on standard forms of von Neu-mann algebras, J. Funct. Anal. 147 (1997), 259-300.
3.
F. Cipriani, F. Fagnola, and J. M. Lindsay, Spectral analysis and Feller properties for quantum Ornstein-Uhlenbeck semigroups, Comm. Math. Phys. 210 (2000), 85-105.
4.
F. Fagnola and R. Quezada, Two-photon and emission process, Inf. Dim. Anal. Quantum Probab. Related Topics 8 (2005), 573-591.
5.
F. Fagnola and R. Rebolledo, The approach to equilibrium of a class of quantum dynamical semigroups, Inf. Dim. Anal. Quantum Probab. Related Topics 1 (1998), 561-572.
6.
F. Fagnola and R. Rebolledo, Notes on the qualitative behaviour of quantum Markov semigroups, Lecture Notes in Math. Open quantum systems. III, 1882, Springer, Berlin, (2006), 161-205.
7.
A. Frigerio, Stationary states of quantum dynamical semigroups, Comm. Math. Phys. 63 (1978), 269-276.
8.
A. W. Majewski and B. Zegarlinski, Quantum stochastic dynamics I, Spin systems on a lattice, MPEJ 1 (1995) Paper 2.
9.
A. Mohari, Markov shift in non-commutative probability, J. Funct. Anal. 199 (2003), 189-209.
10.
Y. M. Park, Remarks on the structure of Dirichlet forms on standard forms of von Neumann algebras, Inf. Dim. Anal. Quantum Probab. Related Topics 8 (2005), 179-197.
11.
Y. M. Park, Ergodic property of Markovian semigroups on standard forms of von Neumann algebras, J. Math. Phys. 46 (2005), 113507-1-113507-13.
12.
K. R. Parthasarathy, An Introduction to Quantum Stochastic Calculus, Birkhäuser, Basel, 1992.
13.
O. Bratteli and D. W. Robinson, Operator algebras and quantum statistical mechanics, Springer-Verlag, New York-Heidelberg-Berlin, vol. II (1981). | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 1, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.809753954410553, "perplexity": 1927.0360752429171}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-47/segments/1510934806124.52/warc/CC-MAIN-20171120183849-20171120203849-00759.warc.gz"} |
https://www.physics.uoguelph.ca/undergraduate-studies/in-course-scholarships | # In-course Scholarships
Amount: Three awards of $1,000. The awards will be made to the top 3 highest combined averages in PHYS*2240 and PHYS*2330. Application is not required. Qualifications: Students registered in a major offered by the Department of Physics with a minimum 80% average, and who have completed PHYS*2240 and PHYS*2330 in the previous academic semester. ## Physics Travel Scholarship Amount: One of$500
This award is given annually to assist students with travel and/or housing costs associated with attending a semester or more of academic study or co-operative work experience at a recognized university outside Canada. Depending on availability of funds, more than one recipient may be selected for this award. Applications must be accompanied by a one-page description of the planned travel, including budget, to the Chair of the Department of Physics at least two months prior to departure.
Qualifications: Student who has completed at least semester 4 of one of the majors in the Physics program with a cumulative average of 80% or greater, and who has obtained a Letter of Permission to attend a University abroad.
Amount: One award of $500. In honour of University Professor Emeritus and former Chair of the Department of Physics, Peter A. Egelstaff. Application is not required. Qualifications: Student who has completed 12.5 course credits, is currently registered in one of the majors in Physics and has a high cumulative average (of at least 80%) in the required Physics courses normally taken in Years 2 & 3 of the major. ## James L. Hunt Scholarship Amount: One of$1,500
Established on honour of Professor Emeritus James L. Hunt, Medal of Merit recipient. The recipient will have achieved the highest cumulative average over 80%. This award cannot be held with any other awards offered by the Department of Physics. Application is not required.
Qualifications: Students registered in any major offered by the Department of Physics that have completed 10.0 credits and have achieved a minimum 80% cumulative average.
## J.B. Reynolds Graduation Medal in Physics
Amount: One award of a medal.
This medal is awarded to a graduating student in the Spring semester or the previous Fall or Winter Semesters. Application is not required.
Qualifications: Student who has completed semester 8 of any of the majors in Physics and who has obtained the highest cumulative average in the required Physics courses of that program, normally taken in semester 5 to 8.
Amount: One award of $1,000. Established in honour of J.L. (Iain) Campbell, former Provost and Vice-President (Academic), of the University of Guelph from 1995 to 2000 and former Dean of the College of Physical and Engineering Science from 1987 to 1995. Application is not required. Qualifications: Student who is currently registered in one of the majors in Physics and who has completed at least 12.50 credits, with a high cumulative average (at least 80%) in the required Physics courses normally taken in Year 2 and 3 of the major. ## MacNaughton Scholarship Amount: One award of$500.
Established by Earl B. MacNaughton, former head of the Department of Physics and founding Dean of the College of Physical Science. Application is not required.
Qualifications: Student who has completed semester 5 and is currently registered in one of the majors in Physics and has a high cumulative average (at least 80%) in the required Physics courses normally taken in semesters 3, 4 and 5 of the major.
Amount: One award of $1,000. In honour of University Professor Emeritus Innes K. MacKenzie. Not tenable with the Egelstaff Scholarship. Application is not required. Qualifications: Students who have completed 12.5 course credits and are currently registered in one of the majors in physics. It is given to a student with a high cumulative standing (of at least 80%) in the required physics courses normally taken in Years 2 & 3 of the major. ## Marie Curie Scholarship in Physics Amount: One award of$1,500
Established in honour of a distinguished Physics Professor Emeritus. Selection will be made to the student with highest cumulative average. Award may be held only once. No application required
Qualifications: Students registered in any major offered by the Department of Physics who have completed a minimum of 15.0 credits and have achieved a minimum of 80% cumulative average. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2069167047739029, "perplexity": 2321.995189144879}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891811352.60/warc/CC-MAIN-20180218023321-20180218043321-00645.warc.gz"} |
http://tutewall.com/changing-windows-command-prompt/ | First of all I must say this is very simple Tech Tip but could be useful when you work with Windows command prompt.
Default command prompt is \$p\$g which represents the current path and greater than sign (>), if you path is closer to root then it takes less space for the windows command prompt. But once you move inside few more levels deep into the directory hierarchy you will find that space you getting to type on the first line is limited or may be even wrapped in to next line, moreover it is very difficult to separate out the prompt and the command you typing or typed.
For ex: if you work with stsadm.exe tool you will be in following folder c:\Program Files\common files\microsoft shared\web server extensions\12\bin . your command prompt will be as follows
But you can easily change your prompt to include carriage return and line feed, so that your input location can be moved to new line.
Try following prompt by executing the command
your command prompt will be in a new line as follows
As you can see now your command is separated from prompt line and it is clear what is your working folder and what is your command to execute. Hope this small tip will help you.
You will find more useful tips related to windows command prompt and other symbols you could use from SCOTT HANSELMAN blog | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9471340179443359, "perplexity": 1461.2734309118193}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-51/segments/1512948592972.60/warc/CC-MAIN-20171217035328-20171217061328-00206.warc.gz"} |
http://en.dsplib.org/content/resampling_spline_ex.html | Using Farrow Filter of Signal Digital Resampling on the Basis of Spline Interpolation
Contents
Introduction
In the previous section there was considered Farrow Filter of signal digital resampling on the basis of cubic Hermite splines (see Figure 1).
Figure 1. Functional Chart of the Optimized Farrow Filter
on the Basis of Cubic Hermite Splines.
The received filter requires only one multiplication by $\frac{1}{2}$ to calculate spline coefficients which can be considered trivial.
Earlier the functional chart of Farrow Filter of digital resampling on the basis of Lagrange polynomial interpolation and examples of its use were considered. We said that Farrow Filter on the basis of Lagrange polynomial interpolation requires one multiplication by $\frac{1}{6}$ and two trivial multiplications by $\frac{1}{2}.$
In this section we will review examples of using Farrow Filter on the basis of cubic Hermite splines and we will compare its characteristics with similar characteristics of the filter on the basis of Lagrange polynomial interpolation.
Recalculating Indexes of Input Signal Samples in case of Piecewise and Cubic Spline Interpolation
We considered this issue in the previous section when we were reviewing examples of using Farrow Filter on the basis of Lagrange polynomial interpolation. When using spline interpolation equations to recalculate indexes of input signal samples are constant, but to give a complete picture we will provide them once again.
Great efficiency of the digital resampler is reached due to using piecewise and cubic spline interpolation and recalculating indexes $n$ of input signal samples $s(n)$, $n =0,1,2, \ldots$ within the interval $[-2, \ldots 1]$ as it is shown in Figure 2.
Figure 2. Recalculating Indexes of Input Signal Samples within the Interval $[-2, \ldots 1].$
Let the sampling frequency of the input signal $s(n)$, $n =0,1,2, \ldots$ be equal to $F_\textrm{s}$. Then the signal $y(k)$, $k =0,1,2, \ldots$ at the resampler filter output will have the following sampling frequency $F_\textrm{y} = \frac{P}{Q} \cdot F_\textrm{s}$. Besides, the first sample of the output signal $y(k)$ is delayed concerning the input one $s(n)$ by the value $0 \leq x_0 <1$.
Here and everywhere in this section, as well as in the previous sections, the variable $n$ indexes samples of the input signal $s(n)$, and the variable $k$ indexes samples of the signal $y(k)$ at the resampler filter output.
As sampling frequencies of input and output signals are various, the same indexes of input and output samples correspond to different timepoints. For example, the $5-$th sample of the output signal $y(5)$ after resampling does not correspond to the $5-$th sample of the input signal $s(5)$. Therefore we shall specify according to what scale we index a sample. We will use three scales: the scale $n$ is for timepoints concerning samples of the input signal $s(n)$, the scale $k$ is for timepoints concerning the output signal and the scale $t$ is within the interval $[-2 \ldots 1]$ to calculate coefficients of the cubic polynomial.
For the $k$ sample of the output signal $y(k)$ according to the scale $k$ it is necessary to calculate the corresponding indexes $n$ of the input signal $s(n)$ according to the scale $n$ (Figure 2a), and then to turn to the scale $t$ within the interval $[-2 \ldots 1]$ to calculate coefficients of the cubic polynomial (Figure 2b). At the same time the pickup time of the $k$ output sample according to the scale $n$ has to be recalculated into the value $0 \leq \Delta_k < 1$ according to the scale $t$.
The pickup time of the $k$ output sample $x_k$ after resampling according to the scale $n$ of the input signal is equal to:
$$x_k = k \cdot \frac{Q}{P} - x_0.$$
(1)
To calculate the cubic polynomial we need four samples of the input signal $s(n)$, $s(n-1)$,$s(n-2)$ and $s(n-3)$ as it is shown in Figure 2a. At that two samples $s(n)$ and $s(n-1)$ have to be more to the right $x_k$, and two other samples $s(n-2)$ and $s(n-3)$ have to be more to the left.
Then the index $n$ of the sample $s(n)$ which corresponds to the timepoint $t = 1$ according to the scale $t$ from -2 to 1 is equal to:
$$n = \lfloor x_k \rfloor + 2,$$
(2)
where the functional $\lfloor x_k \rfloor$ means rounding to the next floor.
The value $\Delta_k$ according to the scale $t$ is equal to:
$$\Delta_k = \lfloor x_k \rfloor + 1 - x_k.$$
(3)
In Figure 3 there is shown the example of recalculating indexes of the input and output signals for the $5-$th of the output sample $y(5)$ under $P = 4$, $Q = 3$, $x_0 = 0.2$.
Figure 3. Example of Recalculating Indexes under $P = 4$, $Q = 3$, $x_0 = 0.2$
The moment $x_5$ according to the scale $n$ in accordance with (1) is equal to:
$$x_5 = 5 \cdot \frac{3}{4} - 0.2 = 3.55.$$
(4)
Then the index $n$ in accordance with (2) is equal to:
$$n = \lfloor 3.55 \rfloor + 2 = 5,$$
(5)
and the parametric variable $\Delta_5$ according to the scale $t$ is equal to:
$$\Delta_5 = \lfloor 3.55 \rfloor + 1 - 3.55 = 0.45.$$
(6)
Thus, it is necessary to calculate coefficients of the cubic polynomial $P(t) = a_0 + a_1 \cdot t +a_2 \cdot t^2 + a_3 \cdot t^3$ according to the following equations:
\begin{equation*} \begin{cases} a_0 = s(n-1), \\ a_1 = \frac{1}{2}\cdot \Big(s(n) - s(n-2)\Big), \\ a_3 = 2 \cdot \Big(s(n-2) - s(n-1)\Big) + a_1 + \frac{1}{2}\cdot \Big(s(n-1) - s(n-3)\Big), \\ a_2 = s(n-2)-s(n-1) + a_3 + a_1. \end{cases} \end{equation*}
(7)
then the value $y(k)$ can be received as the interpolation spline value $P(t)$ for $t=-\Delta_k$, i.e. $y(k) = P \left(-\Delta_k \right)$.
Using Farrow Filter on the Basis of Spline Interpolation to Compensate Fractional Signal Delay
Let the input signal $s(n)$ contain $N=8$ samples as it is shown in Figure 4. We have already used a similar signal to compensate the fractional signal delay when using Farrow Filter on the basis of Lagrange polynomial interpolation
Figure 4. Input Signal of Farrow Filter.
Compensate the fractional delay of this signal by the value $x_0 = 0.25$ of the sampling period with using the resampler on the basis of spline interpolation. In case of changing the fractional delay the sampling frequency is constant, parametric variables $P$ and $Q$ are equal to $P = Q = 1$, and the number of samples at the Farrow Filter output is equal to the number of samples at the Farrow Filter input $N=8$.
The process of compensating the fractional signal delay $s(n),$ $n = 0 \ldots 7,$ shown in Figure 4 is given in Table 1.
Table 1. Compensating the Fractional Signal Delay $s(n)$.
Values $x_k,$ $n$ and $\Delta_k$ are calculated according to (1), (2) and (3) respectively. Further values $s(n-3) \ldots s(n)$ for each value $k$ are given. The zero values $s(n-3) \ldots s(n)$ for $n<3$ and $n>N-1$ being beyond the scope of indexing the signal $s(n),$ $n = 0 \ldots N-1$ are red. The values of coefficients of the cubic polynomial $a_0 \ldots a_3$ calculated according to (7) for the present moment $k$ are given in the next columns of Table 1. At last, in the column $y_S(k)$ there is given the signal value $y_S(k) = P(-\Delta_k)$ at the Farrow Filter output with using spline interpolation. In the last column $y_L(k)$ values are given at the Farrow Filter output with using Lagrange polynomial interpolation as ones to compare. As it is possible to see with the help of Table 1 we have received similar values at the Farrow Filter output when using Lagrange spline interpolation and Lagrange interpolation.
In Figure 5 there are shown the pickup signal $s(n),$ $n = 0 \ldots 7$ (black) and the signal $y_S(k),$ $n = 0 \ldots 7$ after compensating the fractional delay $x_0$ (red).
Figure 5. Input Signal $s(n)$ of Farrow Filter and the Signal after Compensating the Fractional Delay $y_S(k)$.
The program realizing calculation of Table 1 and data for creating Figure 5 is written using DSPL library. The source program code can be received in the DSPL library examples section.
Users of Matlab and GNU Octave can make calculation of Table 1 having executed the following script resample_spline_fd.m.
clear all;
close all;
clc;
p = 1;
q = 1;
x0 = 0.25;
s0 = [1 2 2 1 -0.5 -1 -2 -0.5];
tin = 0:length(s0)-1;
y = zeros(1, floor(length(s0)*q/p));
s = [0, 0, s0, 0, 0];
fprintf('---------------------------------------------------------');
fprintf('-------------------------------------------------------\n');
fprintf('k x_k n d s(n-3) s(n-2) s(n-1) s(n) ');
fprintf('a_0 a_1 a_2 a_3 y_S(k)\n');
fprintf('---------------------------------------------------------');
fprintf('-------------------------------------------------------\n');
for k = 0:length(y)-1
x = k*q/p - x0 ;
n = floor(x) + 2 + 3 ;
d = floor(x) + 1 - x ;
tout(k+1) = x;
a0 = s(n-1);
a1 = 0.5 * (s(n) - s(n-2));
a3 = 2*(s(n-2) - s(n-1))+ a1 + 0.5 * (s(n-1) - s(n-3));
a2 = s(n-2) - s(n-1) + a3 + a1;
y(k+1) = a0 - a1 * d + a2*d^2 - a3*d^3;
fprintf('%d %7.2f %2.0d %7.2f', k, x, n, d);
fprintf('%8.1f %8.1f %8.1f %8.1f ', s(n-3), s(n-2), s(n-1), s(n));
fprintf('%9.3f %9.3f %9.3f %9.3f ', a0, a1,a2,a3);
fprintf('%9.3f\n', y(k+1));
end
fprintf('---------------------------------------------------------');
fprintf('-------------------------------------------------------\n');
figure; stem(tin, s0);
hold on;
stem(tout, y, 'r');
axis([-0.5, 7.5, -2.5, 2.5]);
grid on;
It follows from Table 1 that when compensating the fractional delay parametric variables $\Delta_k = x_0$ are for all $k = 0 \ldots N-1$. In this case Farrow Filter can be interpreted as the third order IIR-filter with changing AFR $\left| H \left(\textrm{e}^{j\cdot \omega} \right) \right|^2$ and group delay $\tau(\omega)$ by setting the required value $x_0$.
Comparative characteristics of AFR $\left| H \left(\textrm{e}^{j\cdot \omega} \right) \right|^2$ and group delay $\tau(\omega)$ of Farrow Filter are given in Figure 6 when using spline interpolation (red) and Lagrange interpolation polynomial (blue) for the different parametric variable value $x_0$.
Figure 6. AFR and Group Delay of Farrow Filters for a Different Value of the Fractional Delay $x_0$ when Using Spline Interpolation (red) and Lagrange Interpolation Polynomial (blue)
Charts of AFR and group delay help draw a conclusion that Farrow Filter when using spline interpolation has smaller non-uniformity of AFR, but slightly bigger non-uniformity of group delay in comparison with Farrow Filter on the basis of Lagrange polynomial interpolation. At the same time changing the time delay is possible only up to $0.4\pi$ rad/s.
Calculating AFR and group delay of Farrow Filters with using spline interpolation for a different value of the fractional delay $x_0$ shown in Figure 6 was also made when using DSPL library. The source program code of calculating AFR and group delay of Farrow Filters can also be received in the corresponding DSPL library examples section.
Users of Matlab and GNU Octave can make calculation of AFR and group delay of Farrow Filters for a different value of the fractional delay $x_0$ having executed the following script resample_spline_fd_filter.m.
clear all;
close all;
clc;
% Check Matlab or GNU Octave
isOctave = exist('OCTAVE_VERSION', 'builtin');
if(isOctave)
end
x0 = 0:0.1:0.9;
s = [0, 1, 0, 0];
figure(1); hold on;
figure(2); hold on;
figure(3); hold on;
w = 0:0.001:pi;
for k = 1:length(x0)
hl = resample_spline(s, 1, 1, x0(k));
hs = resample_lagrange(s, 1, 1, x0(k));
figure(1); subplot(2,5,k); hold on; stem(0:3, hl), stem(0:3, hs, 'sr');
axis([0, 3, -0.2, 1.2]); grid on;
HL = freqz(hl, 1, w);
HS = freqz(hs, 1, w);
tauL = grpdelay(hl,1,w);
tauS = grpdelay(hs,1,w);
figure(2); plot(w/pi, 20*log10(abs(HL)), w/pi, 20*log10(abs(HS)),'r');
axis([0, 1, -20, 2]); grid on;
xlabel('w/pi');
ylabel('|H(e^{jw})|^2, dB');
figure(3); plot(w/pi, tauL, w/pi, tauS,'r');
axis([0, 1, 0, 3]); grid on;
xlabel('w/pi');
ylabel('\tau(w)');
end
To execute the script resample_spline_fd_filter.m and other scripts given below the following function resample_spline.m is required.
function y = resample_spline(s, p, q, x0)
% y = resample_spline(s, p, q, x0)
% Digital resampling by polynomial spline interpolation.
% Function changes input signal s samplerate to p/q times and adds fractional
% delay.
%
% Input parameters
% s - input signal vector [N x 1];
% p - p paramter of samplarate conversion
% q - q paramter of samplarate conversion
% x0 - fractional delay
%
% Ouptut parameters
% y - Resampled signal
%
% Author: Sergey Bakhurin (dsplib.org)
%
if(p>1 && q==1)
y = zeros(1, floor((length(s)-1)*p/q)+1);
else
y = zeros(1, floor(length(s)*p/q));
end
t = zeros(size(y));
s = [0, 0, s, 0, 0];
for k = 0:length(y)-1
x = k*q/p - x0;
t(k+1) = x;
n = floor(x) + 5;
d = floor(x)+1-x;
a0 = s(n-1);
a1 = 0.5 * (s(n) - s(n-2));
a3 = 2*(s(n-2) - s(n-1))+ a1 + 0.5 * (s(n-1) - s(n-3));
a2 = s(n-2) - s(n-1) + a3 + a1;
y(k+1) = a0 - a1 * d + a2*d^2 - a3*d^3;
end
Using Farrow Filter on the Basis of Cubic Hermite Splines as a Digital Signal Interpolator
Consider an example of using the digital resampling filter on the basis of cubic Hermite splines for digital signal interpolation.
Let the input signal $s(n),$ $n = 0 \ldots N-1,$ have $N=8$ signal samples as it is shown in Figure 7a. We have already used this signal as an input signal of the digital filter for changing the fractional delay.
It is necessary to perform digital signal interpolation and to increase the sampling frequency of the signal $y(k),$ $k = 0\ldots K-1$ at the Farrow Filter output by $P=10$ times when using spline interpolation.
In case of digital interpolation the number of signal samples at the output will be equal to (see Figure 7b):
\begin{equation*} K = (N-1) \cdot P +1 = (8-1)\cdot 10 +1 = 71. \end{equation*}
(8)
Recalculating values $x_k,$ $n$ and $\Delta_k$ is also made according to (1), (2) and (3) respectively.
The result of digital interpolation when using Farrow Filter is shown in Figure 7b. Interpolation nodes corresponding to the input signal are black.
Figure 7. Input Signal and the Result of Digital Interpolation when Using Farrow Filter.
The source program code realizing calculating the data for creating Figure 7 is also provided in the corresponding DSPL library reference section.
Users of Matlab and GNU Octave can make digital interpolation with using Farrow Filter having executed the following script resample_spline_interp.m.
clear all;
close all;
clc;
p = 10;
q = 1;
x0 = 0;
s = [1 2 2 1 -0.5 -1 -2 -0.5];
y = resample_spline(s, p, q, x0);
figure(1);
stem(0:length(y)-1, y,'r');
hold on;
stem((0:length(s)-1)*p, s, 'k');
The digital interpolation filter can be interpreted as the filter of lower frequencies. The pulse response characteristic $h(n)$ and amplitude-frequency response $\left|H \left( \operatorname{e}^{j\cdot \omega}\right) \right|^2$ of Farrow Filter of digital signal interpolation are shown in Figure 8 for $P = 10$.
Figure 8. Pulse Response Characteristic and AFR of Farrow Filter on the Basis of Spline Interpolation (Red) and Lagrange Polynomials (Blue)
In Figure 8 it is possible to note that the pulse response characteristic has no continuous derivative in interpolation nodes (it has breakpoints) when using Lagrange polynomials in view of the fact that creating Lagrange interpolation polynomial is performed only according to signal samples without restrictions on derivative continuity. Therefore the rejection level in the scope of the filter AFR blocking is only 28 dB. On the other hand using Hermite splines provides the continuous derivative of the pulse response characteristic of Farrow Filter in interpolation nodes. As a result the rejection level in the scope of the Farrow filter AFR blocking on interpolation spline (the red chart) is 12 dB higher than the same filter, but it is on the basis of Lagrange polynomial interpolation (the blue chart).
The source program code realizing calculating the pulse response characteristic and AFR of Farrow Filter of digital signal interpolation (Figure 9) is also provided in the DSPL library reference section.
Users of Matlab and GNU Octave can make calculation of the digital interpolator filter characteristics having executed the following script resample_spline_interp_filter.m.
clear all;
close all;
clc;
p = 10;
q = 1;
x0 = 0;
s = [0 0 1 0 0];
hl = resample_lagrange(s, p, q, x0);
hs = resample_spline(s, p, q, x0);
w = 0:0.01:pi;
HL = freqz(hl,1,w);
HS = freqz(hs,1,w);
figure(1); subplot(1,2,1);
plot(0:length(hl)-1, hl, 'b'); hold on;
stem(0:length(hl)-1, hl, 'b');
plot(0:length(hs)-1, hs, 'r'); hold on;
stem(0:length(hs)-1, hs, 'rs');
xlabel('n'), ylabel('h(n)');
grid on;
figure(1); subplot(1,2,2);
plot(w/pi, 20*log10(abs(HL)), 'b', w/pi, 20*log10(abs(HS)), 'r');
axis([0, 1, -60, 30]);
xlabel('w/pi');
ylabel('|H(e^{jw})|^2, dB'); grid on;
Using Farrow Filter on the Basis of Spline Interpolation for Fractional Frequency Change of Signal Sampling
Let the sine input signal
\begin{equation*} s(n) = \sin \left( 2\pi \cdot n \cdot \frac{f_0}{F_{\textrm{s}}} \right), ~ n =0 \ldots N-1 \end{equation*}
(9)
with the frequency $f_0 = 6$ kHz have $N = 54$ samples taken with the sampling frequency $F_{\textrm{s}}=26.4$ kHz. We have already used this signal for an example of fractional resampling using Farrow Filter on the basis of Lagrange polynomial interpolation.
The sampling rate ratio $F_{\textrm{s}}$ of the sine signal $s(n)$ to this signal frequency $f_0$ is not the integer $\frac{F_{\textrm{s}}}{f_0} = \frac{26.4}{6}$. As a result the integral number of samples does not cover one sine signal period. The pickup signal is shown in the upper chart of Figure 9.
Change the sampling frequency of the input signal $s(n)$ by $\frac{P}{Q}$ times where $P = 20$, $Q = 11$ and get resampled signals $y_L(k)$ and $y_S(k)$ received on the basis of polynomial and spline interpolation respectively. Samples of the signals $y_L(k)$ and $y_S(k)$ are received with the sampling frequency $F_{\textrm{y}} = \frac{P}{Q} \cdot F_{\textrm{s}} = 48$ kHz. As a result exactly 8 samples will cover one signal period $y(k)$. Recalculating the values $x_k,$ $n$ and $\Delta_k$ is made according to (1), (2) and (3) respectively.
In the second chart of Figure 9 there is shown the signal $y_L(k)$ after digital resampling when using Farrow Filter on the basis of Lagrange polynomial interpolation. In the third chart there is given the signal $y_S(k)$ when using Farrow Filter on the basis of spline interpolation. In the last chart there are given signals of the resampling errors $e_L(k)$ and $e_S(k)$ at the output of Farrow Filters when using Lagrange polynomial interpolation and spline interpolation respectively.
In the lower chart there are given accessed values of normalized average square of the resampling errors $\textrm{NMSE} \big[ e_L(k)\big]$ and $\textrm{NMSE} \big[ e_S(k)\big]$.
Figure 9. Fractional Frequency Change of Signal Sampling.
Continuous lines in Figure 9 show the pickup continuous sine signal. It follows from Figure 9 that after resampling the eight signal samples cover one pickup signal period either when using Lagrange interpolation or when using spline interpolation. At the same time when using spline interpolation the normalized root-mean-square error $\textrm{NMSE} \big[ e_S(k)\big]$ is 0.001 (0.1%) higher.
You can also find the source program code of calculating the data of a digital resampling example in the corresponding DSPL library reference section.
Users of Matlab and GNU Octave can make digital sampling having executed the foolowing script resample_spline_pq.m.
clear all;
close all;
clc;
Fs = 26.4;
f0 = 6;
N = 54;
p = 20;
q = 11;
x0 = 0;
t = (0:N-1)/Fs;
s = sin(2*pi*t*f0);
yl = resample_lagrange(s, p, q, x0);
tr = (0:length(yl)-1)/Fs/p*q;
sr = sin(2*pi*tr*f0);
ys = resample_spline(s, p, q, x0);
figure(1);
subplot(3,1,1); hold on;
stem(t, s);
axis([0,2,-1.5,1.5]); grid on;
subplot(3,1,2); hold on;
stem(tr, yl); hold on; stem( tr, ys,'rs');
axis([0,2,-1.5,1.5]);
grid on;
subplot(3,1,3); hold on;
stem(tr, yl-sr); hold on; stem( tr, ys-sr,'rs');
axis([0,2,-0.1,0.1]);
grid on;
Conclusions
In this section we have reviewed examples of using Farrow Filter on the basis of spline interpolation and comparison of its characteristics with Farrow Filter on the basis of Lagrange polynomial interpolation. The main benefit of Farrow Filter on the basis of spline interpolation is in use only of trivial multiplications to calculate coefficients of an interpolation polynomial.
In this section we have considered a question of recalculating indexes of input signal samples in case of piecewise and cubic spline interpolation. There are given equations for recalculating sampling timepoints of the output signal according to the scale $n$ of the input signal, and also calculating the value $\Delta_k$ according to the scale $t$.
The given equations are used in examples of using Farrow Filter on the basis of spline interpolation to compensate the fractional delay, digital interpolation and fractional change of signal sampling frequency.
Comparisons of AFR and group delay of Farrow Filters families when using Lagrange polynomial interpolation and spline interpolation for a various fractional delay value are given.
Comparisons of Farrow Filter AFR of digital signal interpolation when using Lagrange polynomial interpolation and spline interpolation are also given. It is shown that the resampling filter on the basis of spline interpolation provides a continuous derivative of the interpolated signal at this expense rejection in the scope of the filter blocking is 12 dB better.
Comparison of fractional sine signal resampling when using Farrow Filters on the basis of Lagrange polynomial interpolation and spline interpolation is carried out. It is received that the rated RMSE at the Farrow Filter output on the basis of spline interpolation is 0.1% higher than the similar Farrow Filter on the basis of Lagrange polynomial interpolation has.
Links to the initial program codes realizing calculating all the shown examples with using DSPL library and packages of Matlab and GNU Octave are given.
You can provide your any feedbacks, questions and wishes in the message board or guestbook.
Reference
[1] Kahaner D., Moler C., Nash S. Numerical Methods and Software. Prentice Hall, 1988.
[2] Farrow C.W. A Continuously Variable Digital Delay Element. Circuits and Systems, IEEE International Symposium. 1988, p. 2641–2645. vol. 3
[3] Gardner Floyd M. Interpolation in Digital Modems-Part I: Fundamentals: IEEE Transactions on Communications, Vol. 41, No. 3, March 1993, P. 501-507.
[4] Erup L., Gardner Floyd M., Harris Robert A. Interpolation in Digital Modems-Part II: Implementation and Performance: IEEE Transactions on Communications, Vol. 41, No. 6, June 1993, p.998-1008.
[5] Franck A. Efficient Algorithms for Arbitrary Sample Rate Conversion with Application to Wave Field Synthesis. PhD thesis. Universitätsverlag Ilmenau, Ilmenau, 2012. [PDF]
[6] McConnell J. Analysis of Algorithms: An Active Learning Approach. Jones and Bartlett Publishers, 2001.
Select spelling error with your mouse and press | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7805638313293457, "perplexity": 1466.8296982764518}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-17/segments/1492917122726.55/warc/CC-MAIN-20170423031202-00331-ip-10-145-167-34.ec2.internal.warc.gz"} |
https://core.ac.uk/display/49965 | Location of Repository
## Turbulent transport and dynamo in sheared MHD turbulence with a non-uniform magnetic field
### Abstract
We investigate three-dimensional magnetohydrodynamics turbulence in the presence of velocity and magnetic shear (i.e., with both a large-scale shear flow and a nonuniform magnetic field). By assuming a turbulence driven by an external forcing with both helical and nonhelical spectra, we investigate the combined effect of these two shears on turbulence intensity and turbulent transport represented by turbulent diffusivities (turbulent viscosity, α and β effect) in Reynolds-averaged equations. We show that turbulent transport (turbulent viscosity and diffusivity) is quenched by a strong flow shear and a strong magnetic field. For a weak flow shear, we further show that the magnetic shear increases the turbulence intensity while decreasing the turbulent transport. In the presence of a strong flow shear, the effect of the magnetic shear is found to oppose the effect of flow shear (which reduces turbulence due to shear stabilization) by enhancing turbulence and transport, thereby weakening the strong quenching by flow shear stabilization. In the case of a strong magnetic field (compared to flow shear), magnetic shear increases turbulence intensity and quenches turbulent transport.\ud \u
Publisher: American Physical Society
Year: 2009
OAI identifier: oai:eprints.whiterose.ac.uk:10504
### Suggested articles
To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9164938926696777, "perplexity": 3381.84056094396}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-47/segments/1542039741016.16/warc/CC-MAIN-20181112172845-20181112194845-00314.warc.gz"} |
https://www.mmo-champion.com/threads/2059970-WA2-Astral-Power-Pro-Bar-(Cyous)/page3 | Thread: [WA2] Astral Power Pro Bar (Cyous)
1. Hey cyous, good work as usual.
Treant CD timer needed,
Treant active timer needed if possible
CA CD timer needed
2. Originally Posted by wing5wong
Hey cyous, good work as usual.
Treant CD timer needed,
Treant active timer needed if possible
CA CD timer needed
I'll add some options, but I didn't feel they were necessary. Treants in particular are set and forget.
CA/INC, I can do that.
3. The active timer maybe, but its nice to know when treants will be back up
4. Updated to Version 0.2.4 (Beta)
-- Updated some internal values.
-- Added cooldown tracking for WOE, FON, CA, INC.
-- Enabled the use of TOTAL_DOTS as a global variable. Does not separate MF and SnF, only the grand total. Does not track Stellar Flare because it is designed specifically for Shooting Stars.
-- NEW: Shooting Stars tracking module.
-- May be used anywhere in game.
-- Updates constantly and is highly accurate.
-- Can be modified to track other DOTs for other classes they may benefit from it. (Global values cannot be shared, so you will need to rename your new global.)
Multi-Mode Tracker for Shooting Stars or your DOTs.
-- MODE 0 is for displaying the number number of your active DOTs.
-- MODE 1 is for expected Astral Power per 1 sec from Shooting Stars.
-- MODE 2 is for expected Astral Power per YOUR RATE (in seconds) from Shooting Stars.
MODE may be changed in "Custom Text" on the Display tab.
- - - Updated - - -
Update: v0.2.5 (Beta)
-- Bug fixes to various modules
-- NEW :: Astral Power overflow (101 or more).
Known Issues:
-- Incarnation's cooldown is tied to the GCD and it really screws with the trigger updates.
5. Originally Posted by Cyous
Updated to Version 0.2.4 (Beta)
-- Updated some internal values.
-- Added cooldown tracking for WOE, FON, CA, INC.
-- Enabled the use of TOTAL_DOTS as a global variable. Does not separate MF and SnF, only the grand total. Does not track Stellar Flare because it is designed specifically for Shooting Stars.
-- NEW: Shooting Stars tracking module.
-- May be used anywhere in game.
-- Updates constantly and is highly accurate.
-- Can be modified to track other DOTs for other classes they may benefit from it. (Global values cannot be shared, so you will need to rename your new global.)
MODE may be changed in "Custom Text" on the Display tab.
- - - Updated - - -
Update: v0.2.5 (Beta)
-- Bug fixes to various modules
-- NEW :: Astral Power overflow (101 or more).
Known Issues:
-- Incarnation's cooldown is tied to the GCD and it really screws with the trigger updates.
Thanks so much for your work Cyous, loved the WeakAuras during my WoD time.
Keep up the good work!
;;Edit
Btw, any new video coming out soon ?
6. Originally Posted by Hekkipekki
Thanks so much for your work Cyous, loved the WeakAuras during my WoD time.
Keep up the good work!
;;Edit
Btw, any new video coming out soon ?
Not quite yet.
- - - - -
I need to preposition the modules. After that, I need to find a way to fix Incarnation's cooldown issue.
I'll do something totally awesome and make meta-modules for trinkets. A separate download/import that a will contain every Caster DPS trinket which Balance may use and it will automatically pull your current trinkets.
Since they need to be hardcoded, it's basically 2 major modules using 3 auras
1. Trinket module
2. Trinket module-copycat.
3. Global tables. (Basically, a database of trinkets.)
Shit's gonna be fancy yo.
7. And here was me thinking all you had to do to be a pro boomy was spam flap and lasers :P
Loving the WA man, it's helped me greatly by having all the useful information displayed without any unnecessary clutter etc. Haven't personally ran into any issues with it so far aside from the known Inc thing
8. Fixed the Incarnation using less-than-fancy methods.
After a re-positioning of icons, ill make another update available.
9. Originally Posted by Cyous
Shit's gonna be fancy yo.
Haha, I like the sound of that ^^
10. Updated to 0.2.7 (Beta)
Fixes/Changes:
- Fixed Incarnation
- FOE update based on on combatlog, so its far more responsive.
Overhaul:
- Shiny Bar is slightly larger
- Re-positioned everything
- LEft plenty of room on the top side of the group for trinkets and other auras you may want.
11. Originally Posted by Cyous
Updated to 0.2.7 (Beta)
Fixes/Changes:
- Fixed Incarnation
- FOE update based on on combatlog, so its far more responsive.
Overhaul:
- Shiny Bar is slightly larger
- Re-positioned everything
- LEft plenty of room on the top side of the group for trinkets and other auras you may want.
Nice job!
(not enough words)
12. Here's what 0.2.7 looks like:
- Out of combat, idle.
- In-combat example.
13. Is there an AC timer instead of SS if selected? Same for WoE instead of treants
will give this a testl ater tonight
14. Originally Posted by wing5wong
Is there an AC timer instead of SS if selected? Same for WoE instead of treants
will give this a testl ater tonight
Yes.
Shooting Stars also has 3 different modes to chose from. (A simple edit.) :: "Count: Moonfire and Sunfire" | "Expected ASP in 1sec" | "Expected ASP in Xsec" (you select the 'X' value.)
15. Hello,
I am the getting the following spamming error with 0.2.7 AP_Probar during the import
Code:
Message: [string "return function()..."]:62: attempt to perform arithmetic on global 'FOE_partial' (a nil value)Time: 06/04/16 10:24:31
Count: 246
Stack: [string "return function()..."]:62: in function <[string "return function()..."]:1>
Locals: curASP = 0
Predict_AP = 0
Predict_non_fill = 0
ca_mod = 1
bota_mod = 1
SpellCast = nil
CA = nil
bota_spell = "Blessing of Elune"
BOTA = nil
CA = "Incarnation: Chosen of Elune"
BUFF = nil
E = 0
f_gen = 6
Haste = 0.083899993896484
f_casttime = 1.384
consume = 6
partial = 6
(*temporary) = 0
(*temporary) = nil
(*temporary) = 0
(*temporary) = 0
(*temporary) = 45
(*temporary) = 190984
(*temporary) = 45
(*temporary) = "attempt to perform arithmetic on global 'FOE_partial' (a nil value)"`
I have also deleted the addon (both interface and WTF) and used the link that the first page of the post to reinstall it but the error remains.
Thanks
16. I'm getting it too, now. I'll fix it in a moment.
- - - Updated - - -
Mkay, error is fixed.
Updated the OP's link (no version change).
17. Updated to 0.2.8 (Beta)
Changes:
-- Empowerment tracker now has stacks shown on the first charge.
-- Empowerment tracking is now positioned diagonally to more more appealing on the eyes.
-- Empowerment tracker now uses icons instead of textures. Stack #1 = 100% Opacity. Stacks #2 and #3 are slightly faded out. Goal is to reduce clutter when you are not focusing on the Empowerment stacks. In addition, they're very easy to see when you focus near it. Basically, you'll be looking at the encounter, not this blob of Blue or Yellow.
Coding Changes:
-- None!
Recommendations:
-- Masque makes everything look sooooo much cleaner. I strongly recommend it, and I'm making this bar built with Masque in mind, so alignments could be slightly off.
-- With Masque, you can disable it per addon and/or per object. No conflicts with very simple changes.
18. Originally Posted by Cyous
Updated to 0.2.8 (Beta)
Changes:
-- Empowerment tracker now has stacks shown on the first charge.
-- Empowerment tracking is now positioned diagonally to more more appealing on the eyes.
-- Empowerment tracker now uses icons instead of textures. Stack #1 = 100% Opacity. Stacks #2 and #3 are slightly faded out. Goal is to reduce clutter when you are not focusing on the Empowerment stacks. In addition, they're very easy to see when you focus near it. Basically, you'll be looking at the encounter, not this blob of Blue or Yellow.
Coding Changes:
-- None!
Recommendations:
-- Masque makes everything look sooooo much cleaner. I strongly recommend it, and I'm making this bar built with Masque in mind, so alignments could be slightly off.
-- With Masque, you can disable it per addon and/or per object. No conflicts with very simple changes.
Cyous are you using any special style for Masque ?
19. Set to Blizzard for now. No plug-ins required. But Never hurts to explore.
20. The second image below looks like the Zoomed preset.
Posting Permissions
• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
• | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.3001149594783783, "perplexity": 10556.378010536122}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257647892.89/warc/CC-MAIN-20180322151300-20180322171300-00593.warc.gz"} |
http://talkstats.com/threads/modeling-and-predicting-pathology-from-multivariate-clinical-data.70133/ | # Modeling and predicting pathology from multivariate clinical data
#### jason.parker
##### New Member
Hello, I have a clinical data set that consists of 5 clinical measurements on thousands of tissue samples. Furthermore, each sample has a pathology diagnosis that is 1 of 5 possible diagnoses (all different types of tumors). I am interested in predicting which pathologic class future samples will belong to based on the 5 clinical measurements. I recognize the predictor can be built using machine learning, and I will apply both decision trees and a deep learning method to the data soon. However, I first wanted to explore more simple analyses that could be used to compare the machine learning findings to. An example of the structure of the data are below, averaged across all samples. The numbers are fake.
Code:
Tumor Type 1 Tumor Type 2 Tumor Type 3 Tumor Type 4 Tumor Type 5
Blood Test 1 15.3 +/- 3.2 21.8 +/- 4.3 8.2 +/- 2.3 8.2 +/- 2.3 8.2 +/- 2.3
Blood Test 2 13.4 +/- 3.8 15.9 +/- 3.2 22.8 +/- 11.1 8.2 +/- 2.3 8.2 +/- 2.3
Biopsy Test 1 3.2 +/- 1.3 10.2 +/- 2.9 23.9 +/- 1.2 8.2 +/- 2.3 8.2 +/- 2.3
Biopsy Test 2 3.2 +/- 1.3 10.2 +/- 2.9 23.9 +/- 1.2 8.2 +/- 2.3 8.2 +/- 2.3
Imaging Test 1 3.2 +/- 1.3 10.2 +/- 2.9 23.9 +/- 1.2 8.2 +/- 2.3 8.2 +/- 2.3
Is there a statistical approach to take that might say which clinical tests are "important" for which diagnoses? For example, to determine that Tumor Type 5 is best classified by Blood Test 2 > 15, Biopsy Test 1 < 13, and Imaging Test 1 > 2?
Do any other analysis methods jump out at you besides machine learning that I should consider?
Thanks,
Jason
#### rogojel
##### TS Contributor
hi,
do you have measurements also for the cases where there is no tumor? You could try a logistic regression for each tumor type, if you had negative cases as well.
regards
#### hlsmith
##### Not a robit
As you know you have a classification problem here, so what works for that...many machine learning algorithms. Question, are the continuous lab tests bounded within 0-1.00? Are continuous lab tests correlated?
Yeah, my first inkling was also logistic reg. You wouldn't need tumor free patients if you did regroupings: 1 vs 2-5; 2 vs 3-5,...,4 vs. 1-3, 5 vs. 1-4. But that is a lot of testing when think about correcting for false discovery. But if it is just for fun it would give you a glimpse into relations. Another crude option would be just to run linear reg and treat 1-5 outcomes as a continuous variable. Another option is doing multinomial logistic regression, but you would need to set your reference group accordingly.
Lastly you could look at correlations, you could probably get away with Spearman Rank correlation.
P.S., Would be curious how support vector or random forest may do. I have always wondered if you could run a bunch of short trees say just for each variable (if independent) and pull the split points for each and plot a histogram of the splits to make a decision from. Though running full trees would also help to distinguish Variable Importance. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.21406881511211395, "perplexity": 1516.522292376759}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-51/segments/1544376832559.95/warc/CC-MAIN-20181219151124-20181219173124-00284.warc.gz"} |
https://dienekes.blogspot.com/2017/04/younger-dryas-comet-impact-encoded-in.html | ## April 21, 2017
### Younger Dryas comet impact encoded in Göbekli Tepe?
Fascinating if true.
Mediterranean Archaeology and Archaeometry, Vol. 17, No 1, (2017), pp. 233-250
DECODING GÖBEKLI TEPE WITH ARCHAEOASTRONOMY: WHAT DOES THE FOX SAY?
Martin B. Sweatman* and Dimitrios Tsikritsis
We have interpreted much of the symbolism of Göbekli Tepe in terms of astronomical events. By matching low-relief carvings on some of the pillars at Göbekli Tepe to star asterisms we find compelling evidence that the famous ‘Vulture Stone’ is a date stamp for 10950 BC ± 250 yrs, which corresponds closely to the proposed Younger Dryas event, estimated at 10890 BC. We also find evidence that a key function of Göbekli Tepe was to observe meteor showers and record cometary encounters. Indeed, the people of Göbekli Tepe appear to have had a special interest in the Taurid meteor stream, the same meteor stream that is proposed as responsible for the Younger-Dryas event. Is Göbekli Tepe the ‘smoking gun’ for the Younger-Dryas cometary encounter, and hence for coherent catastrophism? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8768410086631775, "perplexity": 11305.887229055894}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296945368.6/warc/CC-MAIN-20230325161021-20230325191021-00543.warc.gz"} |
https://zhangruochi.com/Subword-Models/2019/12/19/ | ## Character-Level Models
1. Word embeddings can be composed from character embeddings
• Generates embeddings for unknown words
• Similar spellings share similar embeddings
• Solves OOV problem
2. Motivation
• Derive a powerful,robust language model effective across a variety of languages.
• Encode subword relatedness:eventful,eventfully, uneventful…
• Address rare-word problem of prior models.
• Obtain comparable expressivity with fewer parameters.
1. Same architecture as forword-level model but use smaller units: “word pieces”
2. Hybrid architectures: Main model has words; something else for characters
## Byte Pair Encoding
A word segmentation algorithm:
• Most frequent ngram pairs -> a new ngram
• Have a target vocabulary size and stop when you reach it
• Do deterministic longest piece segmentation of words
• Segmentation is only within words identified by some prior tokenizer
For example, all the words in our documents database and their frequency are
{‘l o w’: 5, ‘l o w e r’: 2, ‘n e w e s t’: 6, ‘w i d e s t’: 3}
We can initialize our vocabulary library as:
{ ‘l’, ‘o’, ‘w’, ‘e’, ‘r’, ‘n’, ‘w’, ‘s’, ‘t’, ‘i’, ‘d’}
The most frequent ngram pair is (‘e’,’s’) and its count is 9. So we add the ‘es’ to our vocabulary library.
Our documents database now is:
{‘l o w’: 5, ‘l o w e r’: 2, ‘n e w es t’: 6, ‘w i d es t’: 3}.
Our vocabulary library now is:
{ ‘l’, ‘o’, ‘w’, ‘e’, ‘r’, ‘n’, ‘w’, ‘s’, ‘t’, ‘i’, ‘d’, ‘es’}
Again, the most frequent ngram pair is (‘es’,’t’) and its count is 9，So we add the ‘est’ to our vocabulary library.
Our documents database now is:
{‘l o w’: 5, ‘l o w e r’: 2, ‘n e w est’: 6, ‘w i d est’: 3}
Our vocabulary library now is:
{ ‘l’, ‘o’, ‘w’, ‘e’, ‘r’, ‘n’, ‘w’, ‘s’, ‘t’, ‘i’, ‘d’, ‘es’,’est’}
the rest can be done in the same manner. We can set a threshold of total count of our vocabulary library. By doing so, we can use BPE to construct a vocabulary library to represent all the words based on subword unit.
Google NMT(GNMT) uses a variant of this:
• V1: wordpiece model (Word piece model tokenizes inside words)
• V2: sentencepiece model (Sentence piece model works from raw text)
## Character-level to build word-level
1. Convolution over characters to generate word embeddings
2. Character-based LSTM to build word representation
## CS224n Assignment5
### Character-based convolutional encoder for NMT.
Figure from cs224n. Character-based convolutional encoder, which ultimately produces a word embedding of length $e_{word}$
1. Convert word to character indices. We have a word $x$ (e.g. Anarchy in above figure) that we wish to represent. Assume we have a predefined ‘vocabulary’ of characters (for example, all lowercase letters, uppercase letters, numbers, and some punctuation). By looking up the index of each character, we can thus represent the length-l word x as a vector of integers:where each $c_i$ is an integer index into the character vocabulary.
2. Padding and embedding lookup. Using a special ‘character’, we pad (or truncate) every word so that it has length $m_word$ (this is some predefined hyperparameter representing maximum word length):
3. For each of these characters $c_i$, we lookup a dense character embedding (which has shape $e_{char}$). This yields a tensor $x_{emb}$:
We’ll reshape $x_{emb}$ to obtain $x_{reshaped} in \mathbb{R}^{e_{char} \times m_{word}}$ before feeding into the convolutional network.
4. Convolutional network. To combine these character embeddings, we’ll use 1-dimensional convolutions. The convolutional layer has two hyperparameters: the kernel size $k$ (also called window size), which dictates the size of the window used to compute features, and the number of filters $f$, (also called number of output features or number of output channels). The convolutional layer has a weight matrix $W \in \mathbb{R}^{f \times e_{char} \times k}$ and a bias vector $b \in \mathbb{R}^{f}$. Overall this produces output $x_{conv}$.
For our application, we’ll set $f$ to be equal to $e_{word}$, the size of the final word embedding for word x. Therefore,
Finally, we apply the ReLU function to $x_{conv}$, then use max-pooling to reduce this to a single vector $x_{conv_out} \in \mathbb{R}^{e_{word}}$, which is the final output of the Convolutional Network:
5. Highway layer and dropout. Highway Networks6 have a skip-connection controlled by a dynamic gate. Given the input $x_{conv\_out} \in \mathbb{R}^{e_{word}}$, we compute:
Figure from cs224n. Highway Network (Srivastava et al. 2015)
Where $W_{proj},W_{gate} \in \mathbb{R}^{e_{word} \times e_{word}}$, and $\circ$ denotes element-wise multiplication.
6. Combine above steps together to get our Character-based word embedding model.
### Character-based LSTM decoder for NMT
We will now add a LSTM-based character-level decoder to our NMT system. The main idea is that when our word-level decoder produces and <UNK> token, we run our character-level decoder (which you can think of as a character-level conditional language model) to instead generate the target word one character at a time, as shown in below figure. This will help us to produce rare and out-of-vocabulary target words.
Figure from cs224n. A character-based decoder which is triggered if the word-based decoder produces an UNK. Figure courtesy of Luong & Manning.
We now describe the model in three sections:
1. Forward computation of Character Decoder: Given a sequence of integers $x_i,\cdots,x_n \in \mathbb{Z}$ representing a sequence of characters, we lookup their character embeddings $x_i,\cdots,x_n \in \mathbb{Z}^{e_{char}}$ and pass these as input in to the(unidirectional)LSTM,obtaining hidden states $h1, \cdots, h_n$ and cell states $c_1, \cdots, c_n$
where h is the hidden size of the CharDecoderLSTM. The initial hidden and cell states $h_0$ and $c_0$ are both set to the combined output vector (attentioned) for the current timestep of the main word-level NMT decoder.
For every timestep $t \in { 1, \cdots, n }$ we compute scores (also called logits) $s_t \in \mathbb{R}^{V_{char}}$
Where the weight matrix $W_{dec} \in \mathbb{R}^{V_{char} \times h}$ and the bias vector $b_{dec} \in \mathbb{R}^{V_{char}}$. If we passed $s_t$ through a softmax function, we would have the probability distribution for the next character in the sequence.
2. Training of Character Decoder When we train the NMT system, we train the character decoder on every word in the target sentence (not just the words represented by ). For example, on a particular step of the main NMT decoder, if the target word is music then the input sequence for the CharDecoderLSTM is $[x_1,…,x_n]$ = [,m,u,s,i,c] and the target sequence for the CharDecoderLSTM is $[x_{2}, . . . , x_{n+1}]$ = [m,u,s,i,c,].
We pass the input sequence $x_1, \cdots, x_n$, along with the initial states $h_0$ and $c_0$ obtained from the combined output vector) into the CharDecoderLSTM, thus obtaining scores $s_1,\cdots, s_n$ which we will compare to the target sequence $x_2,\cdots, x_{n+1}$. We optimize with respect to sum of the cross-entropy loss:
3. Decoding from the Character Decoder t test time, first we produce a translation from our word- based NMT system in the usual way (e.g. a decoding algorithm like beam search). If the translation contains any tokens, then for each of those positions, we use the word-based decoder’s combined output vector to initialize the CharDecoderLSTM initial $h_0$ and $c_0$, then use CharDecoderLSTM to generate a sequence of characters. To generate the sequence of characters, we use the greedy decoding algorithm, which repeatedly chooses the most probable next character, until either the token is produced or we reach a predetermined max length. The algorithm is given below, for a single example (not batched).
Figure from cs224n. Greedy Decoding
## Reference
• Course note and slides of cs224n
Donate article here | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 1, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.632970929145813, "perplexity": 4267.908178430618}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-40/segments/1600400241093.64/warc/CC-MAIN-20200926102645-20200926132645-00584.warc.gz"} |
https://www.copperspice.com/docs/cs_api/class_qeasingcurve.html | CopperSpice API 1.7.4
QEasingCurve Class Reference
The QEasingCurve class provides easing curves for controlling animation. More...
## Public Typedefs
typedef qreal (* EasingFunction) (qreal progress)
enum Type
## Public Methods
QEasingCurve (const QEasingCurve &other)
QEasingCurve (Type type=Linear)
~QEasingCurve ()
qreal amplitude () const
EasingFunction customType () const
bool operator!= (const QEasingCurve &other) const
QEasingCurve & operator= (const QEasingCurve &other)
bool operator== (const QEasingCurve &other) const
qreal overshoot () const
qreal period () const
void setAmplitude (qreal amplitude)
void setCustomType (EasingFunction func)
void setOvershoot (qreal overshoot)
void setPeriod (qreal period)
void setType (Type type)
Type type () const
qreal valueForProgress (qreal progress) const
## Friends
QDataStreamoperator<< (QDataStream &stream, const QEasingCurve &easing)
## Related Functions
These are not member functions
QDataStreamoperator>> (QDataStream &stream, const QEasingCurve &easing)
## Detailed Description
The QEasingCurve class provides easing curves for controlling animation.
Easing curves describe a function that controls how the speed of the interpolation between 0 and 1 should be. Easing curves allow transitions from one value to another to appear more natural than a simple constant speed would allow. The QEasingCurve class is usually used in conjunction with the QVariantAnimation and QPropertyAnimation classes but can be used on its own. It is usually used to accelerate the interpolation from zero velocity (ease in) or decelerate to zero velocity (ease out). Ease in and ease out can also be combined in the same easing curve.
To calculate the speed of the interpolation, the easing curve provides the function valueForProgress(), where the progress argument specifies the progress of the interpolation: 0 is the start value of the interpolation, 1 is the end value of the interpolation. The returned value is the effective progress of the interpolation. If the returned value is the same as the input value for all input values the easing curve is a linear curve. This is the default behavior.
for(qreal t = 0.0; t < 1.0; t+=0.1)
qWarning() << "Effective progress" << t << " is << easing.valueForProgress(t);
will print the effective progress of the interpolation between 0 and 1.
When using a QPropertyAnimation, the associated easing curve will be used to control the progress of the interpolation between startValue and endValue:
animation.setStartValue(0);
animation.setEndValue(1000);
animation.setDuration(1000);
The ability to set an amplitude, overshoot, or period depends on the QEasingCurve type. Amplitude access is available to curves that behave as springs such as elastic and bounce curves. Changing the amplitude changes the height of the curve. Period access is only available to elastic curves and setting a higher period slows the rate of bounce. Only curves that have "boomerang" behaviors such as the InBack, OutBack, InOutBack, and OutInBack have overshoot settings. These curves will interpolate beyond the end points and return to the end point, acting similar to a boomerang.
setAmplitude()
## Member Typedef Documentation
QEasingCurve::EasingFunction
This is a typedef for a pointer to a function with the following signature:
qreal myEasingFunction(qreal progress);
## Member Enumeration Documentation
enum QEasingCurve::Type
The type of easing curve.
ConstantValueDescription
QEasingCurve::Linear0
Easing curve for a linear (t) function: velocity is constant.
QEasingCurve::InQuad1
Easing curve for a quadratic (t^2) function: accelerating from zero velocity.
QEasingCurve::OutQuad2
Easing curve for a quadratic (t^2) function: decelerating to zero velocity.
QEasingCurve::InOutQuad3
Easing curve for a quadratic (t^2) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInQuad4
Easing curve for a quadratic (t^2) function: deceleration until halfway, then acceleration.
QEasingCurve::InCubic5
Easing curve for a cubic (t^3) function: accelerating from zero velocity.
QEasingCurve::OutCubic6
Easing curve for a cubic (t^3) function: decelerating to zero velocity.
QEasingCurve::InOutCubic7
Easing curve for a cubic (t^3) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInCubic8
Easing curve for a cubic (t^3) function: deceleration until halfway, then acceleration.
QEasingCurve::InQuart9
Easing curve for a quartic (t^4) function: accelerating from zero velocity.
QEasingCurve::OutQuart10
Easing curve for a quartic (t^4) function: decelerating to zero velocity.
QEasingCurve::InOutQuart11
Easing curve for a quartic (t^4) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInQuart12
Easing curve for a quartic (t^4) function: deceleration until halfway, then acceleration.
QEasingCurve::InQuint13
Easing curve for a quintic (t^5) easing in: accelerating from zero velocity.
QEasingCurve::OutQuint14
Easing curve for a quintic (t^5) function: decelerating to zero velocity.
QEasingCurve::InOutQuint15
Easing curve for a quintic (t^5) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInQuint16
Easing curve for a quintic (t^5) function: deceleration until halfway, then acceleration.
QEasingCurve::InSine17
Easing curve for a sinusoidal (sin(t)) function: accelerating from zero velocity.
QEasingCurve::OutSine18
Easing curve for a sinusoidal (sin(t)) function: decelerating from zero velocity.
QEasingCurve::InOutSine19
Easing curve for a sinusoidal (sin(t)) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInSine20
Easing curve for a sinusoidal (sin(t)) function: deceleration until halfway, then acceleration.
QEasingCurve::InExpo21
Easing curve for an exponential (2^t) function: accelerating from zero velocity.
QEasingCurve::OutExpo22
Easing curve for an exponential (2^t) function: decelerating from zero velocity.
QEasingCurve::InOutExpo23
Easing curve for an exponential (2^t) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInExpo24
Easing curve for an exponential (2^t) function: deceleration until halfway, then acceleration.
QEasingCurve::InCirc25
Easing curve for a circular (sqrt(1-t^2)) function: accelerating from zero velocity.
QEasingCurve::OutCirc26
Easing curve for a circular (sqrt(1-t^2)) function: decelerating from zero velocity.
QEasingCurve::InOutCirc27
Easing curve for a circular (sqrt(1-t^2)) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInCirc28
Easing curve for a circular (sqrt(1-t^2)) function: deceleration until halfway, then acceleration.
QEasingCurve::InElastic29
Easing curve for an elastic (exponentially decaying sine wave) function: accelerating from zero velocity. The peak amplitude can be set with the amplitude parameter, and the period of decay by the period parameter.
QEasingCurve::OutElastic30
Easing curve for an elastic (exponentially decaying sine wave) function: decelerating from zero velocity. The peak amplitude can be set with the amplitude parameter, and the period of decay by the period parameter.
QEasingCurve::InOutElastic31
Easing curve for an elastic (exponentially decaying sine wave) function: acceleration until halfway, then deceleration.
QEasingCurve::OutInElastic32
Easing curve for an elastic (exponentially decaying sine wave) function: deceleration until halfway, then acceleration.
QEasingCurve::InBack33
Easing curve for a back (overshooting cubic function: (s+1)*t^3 - s*t^2) easing in: accelerating from zero velocity.
QEasingCurve::OutBack34
Easing curve for a back (overshooting cubic function: (s+1)*t^3 - s*t^2) easing out: decelerating to zero velocity.
QEasingCurve::InOutBack35
Easing curve for a back (overshooting cubic function: (s+1)*t^3 - s*t^2) easing in/out: acceleration until halfway, then deceleration.
QEasingCurve::OutInBack36
Easing curve for a back (overshooting cubic easing: (s+1)*t^3 - s*t^2) easing out/in: deceleration until halfway, then acceleration.
QEasingCurve::InBounce37
Easing curve for a bounce (exponentially decaying parabolic bounce) function: accelerating from zero velocity.
QEasingCurve::OutBounce38
Easing curve for a bounce (exponentially decaying parabolic bounce) function: decelerating from zero velocity.
QEasingCurve::InOutBounce39
Easing curve for a bounce (exponentially decaying parabolic bounce) function easing in/out: acceleration until halfway, then deceleration.
QEasingCurve::OutInBounce40
Easing curve for a bounce (exponentially decaying parabolic bounce) function easing out/in: deceleration until halfway, then acceleration.
QEasingCurve::Custom45This is returned if the user specified a custom curve type with setCustomType(). Note that you can not call setType() with this value, but type() can return it.
## Constructor & Destructor Documentation
QEasingCurve::QEasingCurve ( Type type = Linear )
Constructs an easing curve of the given type.
QEasingCurve::QEasingCurve ( const QEasingCurve & other )
Construct a copy of other.
QEasingCurve::~QEasingCurve ( )
Destroys the current QEasingCurve object.
## Method Documentation
qreal QEasingCurve::amplitude ( ) const
Returns the amplitude. This is not applicable for all curve types. It is only applicable for bounce and elastic curves (curves of type() QEasingCurve::InBounce, QEasingCurve::OutBounce, QEasingCurve::InOutBounce, QEasingCurve::OutInBounce, QEasingCurve::InElastic, QEasingCurve::OutElastic, QEasingCurve::InOutElastic or QEasingCurve::OutInElastic).
setAmplitude()
EasingFunction QEasingCurve::customType ( ) const
Returns the function pointer to the custom easing curve. If type() does not return QEasingCurve::Custom, this function will return 0.
setCustomType()
bool QEasingCurve::operator!= ( const QEasingCurve & other ) const
inline
Compare this easing curve with other and returns true if they are not equal. It will also compare the properties of a curve.
operator==()
QEasingCurve & QEasingCurve::operator= ( const QEasingCurve & other )
Copy other.
bool QEasingCurve::operator== ( const QEasingCurve & other ) const
Compare this easing curve with other and returns true if they are equal. It will also compare the properties of a curve.
qreal QEasingCurve::overshoot ( ) const
Returns the overshoot. This is not applicable for all curve types. It is only applicable if type() is QEasingCurve::InBack, QEasingCurve::OutBack, QEasingCurve::InOutBack or QEasingCurve::OutInBack.
setOvershoot()
qreal QEasingCurve::period ( ) const
Returns the period. This is not applicable for all curve types. It is only applicable if type() is QEasingCurve::InElastic, QEasingCurve::OutElastic, QEasingCurve::InOutElastic or QEasingCurve::OutInElastic.
setPeriod()
void QEasingCurve::setAmplitude ( qreal amplitude )
Sets the amplitude to amplitude.
This will set the amplitude of the bounce or the amplitude of the elastic "spring" effect. The higher the number, the higher the amplitude.
amplitude()
void QEasingCurve::setCustomType ( EasingFunction func )
Sets a custom easing curve that is defined by the user in the function func. The signature of the function is qreal myEasingFunction(qreal progress), where progress and the return value is considered to be normalized between 0 and 1. (In some cases the return value can be outside that range) After calling this function type() will return QEasingCurve::Custom. func can not be zero.
customType(), valueForProgress()
void QEasingCurve::setOvershoot ( qreal overshoot )
Sets the overshoot to overshoot.
0 produces no overshoot, and the default value of 1.70158 produces an overshoot of 10 percent.
overshoot()
void QEasingCurve::setPeriod ( qreal period )
Sets the period to period. Setting a small period value will give a high frequency of the curve. A large period will give it a small frequency.
period()
void QEasingCurve::setType ( Type type )
Sets the type of the easing curve to type.
type()
Type QEasingCurve::type ( ) const
Returns the type of the easing curve.
setType()
qreal QEasingCurve::valueForProgress ( qreal progress ) const
Return the effective progress for the easing curve at progress. While progress must be between 0 and 1, the returned effective progress can be outside those bounds. For instance, QEasingCurve::InBack will return negative values in the beginning of the function.
## Friends And Related Function Documentation
QDataStream & operator<< ( QDataStream & stream, const QEasingCurve & easing )
friend
Writes the given easing to the stream. Returns a reference to the stream.
Refer to Serializing Data Types for additional information.
QDataStream & operator>> ( QDataStream & stream, const QEasingCurve & easing )
related
Reads from the stream into the given easing. Returns a reference to the stream.
Refer to Serializing Data Types for additional information. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7040218114852905, "perplexity": 9420.913108473402}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656103626162.35/warc/CC-MAIN-20220629084939-20220629114939-00065.warc.gz"} |
http://climateaudit.org/2007/03/27/burger-and-skill/?like=1&source=post_flair&_wpnonce=0619346065 | ## Bürger and "Skill"
CA readers have followed some of the interesting reviews at Climate of the Past, where some of the exchanges have been lively (although most papers don’t seem to attract much comment.) Two reviews are in on Bürger’s most recent submission and a 3rd reviewer has been invited to give an opinion. However, he’s slow about these things. (CPD reviewers are allowed to identify themselves – Joel Guiot has submitted a review under his own name, and the third reviewer will as well.) The third reviewer is sometimes distracted by interesting by-ways in an article and this is no exception. So I thought that I’d explore some of these by-ways on CA for him. It’s possible that Reviewer #3 will draw on some of this material, although it’s too lengthy and ambling for a review.
Bürger discusses the topic of RE significance – a topic which I think is important and one which is in a very unsettled state, as Bürger observes, noting that MM05a and MM Reply to Huybers had reported that very high RE values could be generated from red noise treated in an MBH manner resulting in a 95% benchmark of over 0.5 (he expressed it differently), while MBH and Huybers had argued for a benchmark of 0. He didn’t discuss Ammann and Wahl 2007 arguing for and using 0.0 as a benchmark (based on their rejected GRL submission). I’ll discuss this further, but first I got intrigued by a point made by Referee #2 about Bürger’s use of the term “skill” which had echoes, in my opinion, of a broader issue.
Referee #2 observed that the paper was “difficult to read”, an observation that TCO would doubtless have agreed with and I agree with. I’ve spent a lot of time on the paper and it’s taken me an unduly long time to understand what he’s doing. One more reason for archiving code. If I could read his code, I could sort out what was explained poorly. Anyway Referee #2 observed:
in this paper, the term “skill” is never clearly defined.
The term “skill” is not incidental. Bürger uses the term “skill” 50 times – 8 times in his abstract, 16 times in his introduction and 9 times in his conclusion. Indeed, his main conclusions are about “skill” – he argues that MBH claims of skill in the range of 50% are over-estimates and that “more realistic estimates” of MBH98 skill are about 25%. Thus, without ever defining skill, Bürger nonetheless manages to estimate it. You can sort of figure out what he means in any given context, but he moves rather fluidly from a colloquial understanding of the term to its use to denote a very particular statistic/skill score. Referee #2 illustrated the fluid usage through the following sentence (just one possible example):
“Calibrating is done,…, by optimizing the model skill for a selected sample (the calibration set) and is almost affected by the presence of sampling noise. This renders the model imperfect, and its true skill is bound to shrink. But it is this skill that is relevant when independent data are to be predicted”.
The referee observed (correctly in my opinion):
The expression “by optimizing the model skill” is rather puzzling because (1) there is no “the skill” but “a” skill among many possible skills, and (2) the parameters of a given statistical model are estimated by optimizing a given criterion (Mean Squared Error, likelihood function, etc) that can be very different for a chosen skill score that has been calculated after the parameter estimation step.
The referee then proceeds to make sensible observations about the need to carefully define terms citing Thornes and Stephenson 2001 as an example of how skill measures can be clearly defined. Instead of responding to the referee’s concern about the failure to define the term “skill” and his concern about the fluidity of its use, in my opinion, Bürger missed the point about the fluid use of terms, choosing instead to debate incidental aspects of how the referee illustrated the point. Bürger:
1. (“skill”): – For the introductory statements, “skill” was intentionally used in a more colloquial and general sense. For any skill score measuring the correspondence of a modeled quantity to observations the following is almost axiomatic: If a model, calibrated by whatever method, is applied to independent data the skill is expected to shrink. I should be very surprised if the rev disagrees on this point. (If he/she is able to provide a counterexample it will of course be considered accordingly.) The actual law of shrinkage certainly depends on the chosen model and score. Eq. (4), for example, applies to cross validity, Rc, for model estimates based on least-squares. The scores mentioned by the rev, such as odds ratio (ORSS) and Peirce (PSS), are binary and as such not really appropriate for climate reconstructions.
I didn’t think that the referee was contesting the argument that the value of a statistic will typically decline in a verification sample, but Bürger’s use of the phrase “model skill” in the context of “optimizing the model skill”. Similarly the referee also didn’t propose the Odds Ratio as a specific test, but merely illustrated that there can be many ways to measure skill. While Bürger studied RE and CE statistics in an MBH context (and the results expressed narrowly are of interest), I think that Bürger’s fluid terminology has allowed him to reify the colloquial idea of skill with a particular statistic without properly distinguishing the two.
The concern over fluid use of the term “skill” reminded me of two interesting exchanges about the topic – one at the House Energy and Committee hearings last summer; the other at the blogs of Pielke Sr and James Annan about a year ago.
House Energy and Commerce Committee Hearings
Oddly enough, the House Energy and Commerce Committee hearings had a very illuminating exchange involving Wegman and Mann, illustrating a communication problem between statistical and meteorological communities.
Wegman testified:
when I read the paper [MBH98] originally, it took me probably 10 times to read it to really understand what he was trying to say. He uses phrases that are not standard in the literature I am familiar with. He uses, for example, the phrase “statistical skill” and I floated that phrase by a lot of my statistical colleagues and nobody had ever heard of that phrase, statistical skill. He uses measures of quality of fit that are not focused on the kind of things typically we do.
Of course, as Mann observed at the NAS Panel hearings, he is “not a statistician”. Mann later had an opportunity to comment on Wegman’s point and stated:
That was another very odd statement on his part, and I found his lack of familiarity with that term somewhat astonishing. The American Meteorological Society considers it such an important term in the context of statistical weather forecasting verification that they specifically define that term on their website and in their official literature. And in fact it is defined by the American Meteorological Society in the following manner: “A statistical evaluation of the accuracy of forecasts or the effectiveness of detection techniques.” Several simple formulations are commonly used in meteorology. The skill score is useful for evaluating predictions of temperatures, pressures, et cetera, et cetera, so I was very surprised by that statement.
Mann’s observation about the American Meteorological Society can be confirmed, as it does indeed define skill as follows:
“A statistical evaluation of the accuracy of forecasts or the effectiveness of detection techniques.” Several simple formulations are commonly used in meteorology. The skill score (SS) is useful for evaluating predictions of temperatures, pressures, or the numerical values of other parameters. It compares a forecaster’s root-mean-squared or mean-absolute prediction errors, Ef, over a period of time, with those of a reference technique, Erefr, such as forecasts based entirely on climatology or persistence, which involve no analysis of synoptic weather conditions: If SS > 0, the forecaster or technique is deemed to possess some skill compared to the reference technique.
To which, Wegman later replied:
My own sense is that if you look at, for example, this matter of statistical skill, it doesn’t matter that the American Meteorological Society says what statistical skill is. Statisticians do not recognize that term. I went around to a whole dozen or so of my statisticians network and asked them if they knew what they were talking about. It is my contention that there is a gulf between the meteorological community and the statistical community.
We examined, for example, this committee that is on probability and statistics of the American Meteorological Society. We found only two of the nine people in that committee are actually members of the American Statistical Association, and in fact one of those people is an assistant professor in the medical school whose specialty is bio-statistics The assertion I have been making is that although this community, the meteorological community in general and the paleoclimate community in particular, used statistical methods. They are substantially isolated.
Pielke and Annan
While the exchange between Wegman and Mann illustrates, at a minimum, a communication problem, it doesn’t exclude the possibility that the two communities might be doing similar things using different terminology. Econometricians use somewhat different language than signal processors for multivariate analyses, but one can often identify common features under the terminology.
Light is shed on the AMS definition through discussions took place last year at Roger Pielke Sr’s blog here and at James Annan’s blog here
Pielke Sr comment defined “skill” in terms of how closely the model fir observations.
I interpret skill as an absolute measure of forecast error with respect to observed data. I agree that skill of different models can be compared with each other, as long as observed data is the reference.
James Annan argued vehemently against “skill” being appropriately measured against actual data as opposed to against a reference point both in terms of the logic and in terms of the AMS definition:
In saying “I interpret skill as an absolute measure of forecast error with respect to observed data”, you are demonstrating that your use of the term “skill” differs from the AMS reference which you cited and other similar references…They all explicitly define skill as a comparative measure in which the data are used to determine which of two competing hypotheses (generally a model forecast and a simple reference such as persistence) is more accurate. as I said previously, using your own idiosyncratic definition is liable to mislead your readers. Your measure is simply not “skill” as understood in the forecasting field.
Incredibly, it turns out that Roger is claiming it is appropriate to use the data themselves as the reference technique! If the model fails to predict the trend, or variability, or nonlinear transitions, shown by the data (to within the uncertainty of the data themselves) then in his opinion it has no skill. …I repeat again my challenge to Roger, or anyone else, to find any example from the peer-reviewed literature where the target data has been used as the reference hypothesis for the purposes of determining whether a forecast has skill.
After this exchange, Henk Tennekes observed:
To both of you, I suggest that your quest for an objective and universally valid metric for the measurement of skill is unlikely to succeed. Skill, however defined, is ultimately a qualitative judgment, not a quantitative one. More precisely, it is a judgment, not a calculation. Being an old man, I want to remind you that I have written more than once about the added value of human skills. You might wish to delve into my Illusions paper, and into Michael McIntyre’s response (Weather 43, 294-298, 1988).
Apart from that I want to apologize for the loose way I fooled around with the skill concept in my blog and in earlier speeches and opinion pieces. Flowery language has its own problems, unfortunately.
The last sentence here closes the circle back to Bürger’s article – “flowery language has its own problems”. Quite so.
Annan’s challenge, to find a peer-reviewed article, any article, in which the “target data has been used as the reference hypothesis for the purposes of determining whether a forecast has skill” contrasts rather sharply with the routine use of actual data in hindcasts to claim “skill”. Whether meteorological forecasting terminology involving, as Annan says, a comparison to a reference forecast, should be applied to hindcasting reconstructions, is, I think, an open question.
Prior Paleoclimate Usage of the Term “Skill”
I also became a bit intrigued at exactly when the term “skill” started being used in paleoclimate literature. All the current dendrochronological verification tests except the CE statistic are described in Fritts 1976, which uses the term Reduction of Error (RE). The CE statistic seems to have entered tree ring literature with Briffa et al 1988 (cited by Bürger). About the RE statistic, Fritts 1976 merely says:
any positive value indicates that there is some information in the reconstruction. (p.24)…
Jacoby et al 1985 say:
Although not very well known outside the atmospheric science literature, the RE statistic is rigorous estimate of statistical estimates. An RE greater than 0 is regarded as proof that the estimates are an improvement over using just the mean (Gordon and Leduc, 1981
The term skill is used in Preisendorfer 1988 uses the term “skill”, who uses the term “hindcast skill”, where, as I read his equation 9.48, it is equivalent to what we would call the calibration r2 statistic. Preisendorfer, in his usual interesting bibliographic notes, discusses linear regression going back to Wiener and, in a meteorological context, refers to a couple of articles by Davis in the mid-1970s which use the term “skill”.
The transfer of the term “skill” to dendroclimatology seems to have been done by Jacoby and D’Arrigo in connection with their NH temperature reconstruction in the late 1980s. Jacoby and D’Arrigo Clim Chg 1989 substantially increases the properties attributed to the RE statistic from the earlier publications (even though no new statistical texts demonstrated the upgrade):
The reduction of error is a rigorous method of testing significance (Gordon and Leduc 1981). Any value above 0 indicates significant predictive skill. (p 47)
Fritts 1991 uses the term skill with less forcefulness as follows:
Any positive value of RE indicates that the regression model, on the average, has some skill and that the reconstruction made with the particular model is of some value..
D’Arrigo and Jacoby, 1992 (Climate since 1500). made a similar claim with the first hint of potential problems resulting from the presence of trends:
Any positive RE value shows that there is considerable skill in the verification period estimates as compared to the calibration period mean (Gordon and LeDuc 1981). The strength of the RE in this case may however partly reflect a difference in the mean of the calibration and verification periods (Gordon and LeDuc 1981).
The influential study Cook et al 1994 re-stated the various Fritts’ tests, together with the CE statistic. About the RE statistic, they observed:
Thus RE>0 indicates that the reconstruction is better than the calibration period mean. However there is no way of testing the RE for statistical significance. Note that x in the denominator will not produce the true corrected sum-of-squares unless it is identical to the verification period mean. Consequently a large difference in the calibration and verification means can lead to an RE greater than the square of the product-moment correlation coefficient. This occasional odd behaviour suggests that they should be interpreted cautiously when the data contains trends or are highly autocorrelated.
I’ll check this reference for its use of the term “skill” (but can’t find the article right now – it’s somewhere here).
The RE statistic got discussed in the context of MBH98 claims about the verification r2 statistic (together with actual values of ~0 for the verification r2 statistic.)
Back to Bürger
Let’s grant Bürger a little license for terminological inconsistency and then examine actual usage to see if there are some distinct usages that we can follow. He cites a number of articles from psychometric literature (Raju et al 1997; Cattin 1980) in which he says:
skill is accordingly being referred to as crossvalidity
In examining the underlying references, “cross-validity” in Raju et al is equivalent to what we would call “verification r2”. Bürger’s equation (4) says that the verification r2 in a multiple regression study is necessarily less than the calibration r2. He goes on to say:
Equation (4) applies to models estimated by ordinary least squares and thus to all reconstructions (“predictions”) that are based on some form of multiple regression.
I suspect that this is true, but there are differences between Partial Least Squares Regression and OLS regression. You shouldn’t just say this sort of thing, unless you have a citation. However, the salient thing here is that “skill” is said to be defined by a statistic that is equivalent to a verification r2 statistic. This however is the last we hear of this statistic, as Bürger moves into a lengthy series of RE and CE calculations for MBH98 flavors. These calculations are by far the most focused part of the paper. As a referee, I’m not sure whether I should be saying what should be in or out of a paper – I find many referee suggestions of this type to be annoying – but, in this case, as a blogger, I think that Bürger should ditch most of the theoretical stuff and focus on simply reporting the flavor calculations, staying away from metaphors and unfocused terminology.
After doing hundreds of RE and CE calculations under various permutations, Bürger proposes that these simulations enable him to estimate the skill of the MBH98 reconstruction, which he places at 25%, less than MBH claims of about 50%.
Here there is an interesting difference between how he handles the RE statistic and how a statistician would view it. The viewpoint of a statistician is always that one is using a statistic (verification r2, RE, or for that matter, Durbin-Watson or more exotic statistics) against a null hypothesis. On the other hand, Bürger’s viewpoint is that “skill scores” are estimates of the “skill” of the model, with the term “skill” somewhere morphing into an identification with percentage explained variance (with RE, CE two variants). One quickly gets into deep epistemological waters here.
It seems to me that the problem is almost identical to what we saw with Juckes’ attempts to claim 99.99% significance. In my comment on Juckes, I observed:
There is a large economics literature on the topic of “spurious” or “nonsense” correlations between unrelated series [Yule 1926; Granger and Newbold 1974; Hendry 1980; Phillips 1986 and a large literature]. Yule’s classic example of spurious correlation was between alcoholism and Church of England marriages. Hendry showed a spurious correlation between rainfall and inflation. The simulations performed in Juckes et al have virtually no “power” (in the statistical sense) as a test against possible spurious correlation between the Union reconstruction and temperature. A common, but not especially demanding, test is the Durbin-Watson test [Granger and Newbold 1974], whose use was encouraged by the NRC Panel (p. 87). According to my calculations, the Union Reconstruction failed even this test (see http://www.climateaudit.org/?p=945 ).
I also observed that it was trivial to develop an alternative chronology with different medieval-modern relationships that was also 99.99% significant through slight variations in proxy selection. Obviously both reconstructions could not be 99.99% significant — a point which seems interesting to me, but which Juckes chose not to respond to.
IMHO the problem with Juckes’ simulations is that, in null hypothesis terms, they simply tested the Union reconstruction against a null hypothesis of randomly generated AR1 red noise. I agree that the time series properties of the Union reconstruction are inconsistent with it being randomly selected AR1 noise. The trouble is that that is not the issue: the issue for these reconstructions is twofold: (1) do “key” proxies contain non-climatic trends, which have a spurious correlation with temperature in the calibration period? (2) has the selection of proxies into subsets been biased towards the inclusion of HS-shaped proxies (regardless of whether the reasons are “good”)?
Despite all of Bürger’s work, he doesn’t seem to have grasped either nettle. In particular, he doesn’t mention bristlecone pines. The \$64 question for MBH98 is whether there is a spurious relationship with bristlecones in a complicated multivariate setting with other proxies functioning as white noise or low-order red noise – very much the viewpoint of MM05b and our Reply to Huybers (MM05 EE curiously is not cited by Bürger, although he makes many citations to us and not disparagingly). I don’t know how you can do a statistical evaluation of MBH98 without taking note of the non-robustness of its results to the presence/absence of bristlecones. Thus, doing thousands of simulations on the basis that bristlecones are a valid proxy and hoping that this will shed some light on the “skill” of MBH98 seems a pointless exercise to me.
Having said that, Bürger is a thoughtful guy and there’s interesting material in the article. I didn’t enjoy reviewing it at all. I’;ve only written up about half my notes here. At every step, I wanted to act as a friendly editor and send a cleaned-up version to him focusing and what is salvageable, rather than criticizing things. In this case, I think that would be more constructive and save a long song-and-dance. On the other hand, Referee #1 (Joel Guiot), an editor of CP, liked the article as it is.
1. bernie
Posted Mar 27, 2007 at 11:38 AM | Permalink
God, am I glad the “skill” point has been cleared up. I also had never heard of it in reference to statistics previously and it seemed to refer to such a fundamental property I was feeling mightily embarrassed. Now it turns out that it is a term peculiar to meterologists. The lesson is I should have asked earlier. It seems that in this field nothing is as simple as it could be and people display a penchant for talking knowingly among themselves.
2. Steve McIntyre
Posted Mar 27, 2007 at 11:42 AM | Permalink
I wouldn’t be so bold as to say the point is “cleared up”. I’m merely turning over a stone.
3. bernie
Posted Mar 27, 2007 at 11:55 AM | Permalink
Steve:
More precisely you have lessened my embarrassment by pointing out that the “skill” term is (a) particular to meterologists and (b) apparently means different things to different meterologists!!
4. Michael Jankowski
Posted Mar 27, 2007 at 12:05 PM | Permalink
What am I missing? Wegman says neither he nor statisticians he’s asked have ever heard the phrase “statistical skill.” The AMS quote does not address this – “skill” and “skill score” are not the phrase in question. Obviously, from the AMS quote, the term “skill” is statistical in meaning, and we can tell from this what Mann means…but this makes the invention/use of a phrase “statistical skill” redundant, non-AMS-standard, and potentially confusing.
I do find it amusing, however, that Mann resorts to the AMS to defend himself. I see a lot of criticism about meteorologists “not being climate scientists,” often used to discredit folks such as Dr. William Gray.
5. John A
Posted Mar 27, 2007 at 12:24 PM | Permalink
I can’t be the only person who thinks that the flowery language combined with confusing (and sometimes deceptive) uses of terms like “skill” is used to mask the absolute banality of what they are doing.
No-one wants to say “we used least squares regression” or “we copied the method used by other people in the field because we don’t know any better”.
On the Internet there’s something called the “Post-Modernism Generator“, a computer script which will create an essay, complete with citations, that is logical gibberish. I’m sure that Steve could produce a similar “write your own dendroclimatology paper” which would look identical but mean nothing.
In politics, you’d call this “sexing up the dossier”
6. Posted Mar 27, 2007 at 12:26 PM | Permalink
This really resonated with me. The term “skill” has been bothering me for a long time.
I am not a statistician but I have studies statistics (both in the context of econometric models and the rather more straightforward kind we use in experimental economics.
In my interactions both within the field of economics as well as with people who work in psychology, sociology and evolutionary biology, we realize that sometimes we call the same things by different names. On the other hand, we all know enough standard statistics to be able to define any concept in terms that others with similar statistical and mathematical background can understand.
Thank you, Steve, for this exposition, yet I am still confused about this magic term, “skill”, which I had never heard before stumbling upon the climate reconstruction literature ;-)
Somewhat related:
In my Intro Stats class, we are just at the point where I try to get across to students the fundamental principle that hypotheses are not supposed to be formed based on observed patterns in the data set against which they are going to be tested. This is always the most fun and challenging part as the world is full of people who “succeed” by doing just that.
Sinan
7. jae
Posted Mar 27, 2007 at 2:04 PM | Permalink
I think the third reviewer dissected the skill issue with great skill!
8. Curt
Posted Mar 27, 2007 at 2:10 PM | Permalink
I am struck by Mann’s reference to the AMS definition of skill, which refers entirely to forecasting skill, wherere predictions of measurable quantities can be compared to the later actual measurements. I can’t see how this has much of anything to do with reconstructions, where the whole point is to try to come up with values in the absence of real measurements.
9. Bill F
Posted Mar 27, 2007 at 2:42 PM | Permalink
Ok, color me confused. I am a geologist who doesn’t particularly like to deal with statistics and am lucky enough to work in a portion of the field where when I need to work on statistical issues, I can ask somebody else to help me with it. As such, when it comes to discussing what a particular statistical test means, I tend to look at the bottom line instead of the multiparagraph explanation with equations involved.So when I read Amman getting worked up because Pielke dared to suggest measuring the skil of a forecast by comparing it to actual data, I about lost it.
Lets stop with “the flowery language” and talk about what the point of trying to demonstrate “skill” is. What everybody is saying…using a wide variety of terminology…is that they want their model/forecast to be as close to reality as possible. The AMS definition is based off of comparing their forecast to other forecast methodolgies…why? Juckes wanted to compare his reconstruction to noise…why? Why not take actual data and then compare the ability of the model to match that data? In know in some cases the real data isn’t available, but in alot of cases it is. So why measure your model against something other than reality?
Maybe I am being way too simplistic about this, but it seems like the ideal way to examine a given reconstruction would be to take the portion of that reconstruction for which actual data are available and compare it to the real data to see if it matches up. For multi-proxy methods, this would require examining each series to see if it matched local conditions. If the reconstruction can’t match the real data, you don’t have any business relying on it as evidence of past conditions. At that point, the “skill” of the reconstruction is really a meaningless term because it isn’t predicting reality.
If I am missing something, please let me know, but I just don’t see why these reconstructions should be evaluated any other way before they are evaluated against the real word
10. Mark T.
Posted Mar 27, 2007 at 3:25 PM | Permalink
Maybe I am being way too simplistic about this, but it seems like the ideal way to examine a given reconstruction would be to take the portion of that reconstruction for which actual data are available and compare it to the real data to see if it matches up. For multi-proxy methods, this would require examining each series to see if it matched local conditions. If the reconstruction can’t match the real data, you don’t have any business relying on it as evidence of past conditions. At that point, the “skill” of the reconstruction is really a meaningless term because it isn’t predicting reality.
They do this, actually. That’s how Mann, et. al. have determined that their proxies are viable back in time. They perform the reconstruction and compare it to temperature, getting reasonable correlations. Unfortunately for them, the statistical properties of the “signals” change over time, so what correlates well during their so-called calibration period, is of little use beyond that range. Also, the correlations probably work rather well against CO2 change, rather than temperature change (PCA does not attach a little white flag to the result that says “I’m temperature” or “I’m CO2”). The correlation also apparently falls apart in recent time, which is known as “the divergence problem.” Yeah, it’s a problem alright.
Mark
11. Steve McIntyre
Posted Mar 27, 2007 at 3:38 PM | Permalink
#9. Bill – you should read some of my old posts on Briffa’s “explanation” of the divergence problem -maybe google Briffa cargo cult. Maybe someone will link to them.
12. Posted Mar 27, 2007 at 3:49 PM | Permalink
Re: Bill F
Bill, your post presents a good opportunity to address a number of issues.
First, some notes on the nature of Statistics.
Most commonly used statistical techniques assume that the data set one is working with is a random sample of independent observations from a larger population. The properties of estimates and tests are derived on the basis of being able to repeatedly randomly and independently sample out of this population. Since, with any given data set, we are looking at a random subset of all possible observations, there will be some variation in the values of statistics that we compute from data. This is, in a nutshell, what is called “sampling error”.
On the other hand, in a lot of contexts (examples abound in economics), we just do not have that option. One particular case is when the researcher is dealing with historical data. The fact that there is one and only one history and it is not the result of a controlled properly randomized experiment cannot be stressed enough.
Now, think about the history of temperature measurements at a particular location. There is only one such series. It is not possible to go back and sample another sequence of temperature measurements with another set of controlled conditions. The history of temperature measurements is immutable.
So, suppose now, I fit some curve using some method to this series of historical observations. Suppose that the curve I fit matches the behavior of what I have observed thus far perfectly. (That is, its within sample behavior is excellent). Can I confidently extrapolate from this? Can I predict what future temperatures will be based on this beautiful fit?
A favorite quotation of mine (I don’t remember who said it) goes like this:
Forecasting is like driving a car with all the windows painted black by listening to the directions given by someone who is peering through a hole in the back of the car looking at the road behind you.
So, sometimes you are lucky and if the road behind you is straight, the road ahead is also straight. But, occasionally, there is that sharp curve on the hillside. You will definitely find out about the curve, but only after you have fallen off of it. That is, we cannot tell what the future holds based on the past.
So far, I have said nothing about temperature reconstructions. From what I can understand, the methodology goes something like this:
There is a period of time where we have both historical temperature measurements and measurements on some other variables which we believe to be influenced by temperatures (say, tree ring widths). Can we construct the relationship between these proxies and temperature today, and say something about temperatures in the past? How can we say we have come up with a good description of the relationship between temperatures and tree ring widths?
Clearly, at any given point in time, temperatures cause some of the variation in tree ring widths. (It is also possible that the growth rate of trees today cause some of the temperature variation today and tomorrow). In most normal formulations, therefore, temperature is an explanatory variable and tree ring width is a response variable.
In climate reconstruction, things are the other way around: In such constructions, tree ring width becomes the explanatory variable and temperature becomes the response variable (because the researcher wants to say something about the temperature in time periods for which we have tree ring width observations but no temperature observations).
This, I think, they refer to as “inverse regression”. While one can find quite a few scholarly articles on this topic, I believe reversing the roles of variables from the actual processes that generate the observations is to be avoided. Anyway, I digress.
So, temperature reconstructions regress temperatures from the recent periods on tree ring widths in the same period. That gives them an equation into which they can plug in a tree ring width and get back a temperature estimate.
How good is this equation? Well, there are two ways to answer this. One way, which all of this stuff about “skill” focuses on is to look at how well it fits the data in the last 150 or so years. The other way, is to test the reconstruction with data that is out of sample.
This is where Steve M.’s mantra about updating the proxies comes in. We cannot go back in the past and see how well the equation performs at estimating the temperature because we do not, will never, know the temperature in a particular location in 1543.
On the other hand, we are measuring temperatures daily. So, it is possible to take modern tree ring widths, plug it into the equation we came up with, predict temperature and compare it to reality. This is a far stronger test of how good proxies are than their ability to match the actual relationship between tree rings and temperature.
What meteorologists do is exactly this. They predict key variables in advance, and a comparison between that prediction and the actual observation allows us to compare how good they are at predicting. On the other hand, a good fit within sample tells us nothing about the ability of a model to predict out of sample observations.
At the time of the HS, IIRC, MBH used proxies that came up to 1980. That means we now ought to have, for each proxy, 27 data points, out of the original sample, which we can use to evaluate the performance of these reconstructions. This is the only test that we can do that actually matters.
Whether goodness-of-fit within sample is measure using $R^2$ or RE or something else is almost entirely irrelevant because those measures of fit give us no real information about how well the proxies predict temperatures in the time periods in which we have absolutely no idea what the real temperatures were.
I have oversimplified some things to keep the post from getting very long (and it is already too long, apologies).
Sinan
13. Posted Mar 27, 2007 at 4:04 PM | Permalink
Re: 12
Correction:
This is a far stronger test of how good proxies are than their ability to match the actual relationship between tree rings and temperature.
What I had meant to type was:
This is a far stronger test of how good proxies are and their ability to match the actual relationship between tree rings and temperature.
Sinan
14. bernie
Posted Mar 27, 2007 at 4:11 PM | Permalink
Sinan:
I hope you get a reaction from those who have been working this issue because your very clear statement is exactly the way I have been thinking about it. The added caveats are that all models assume essentially – all other climate variables and variable impacting the width of tree rings being equal and that we actually can agree on the key variable, namely, the temperature. Even so, you are right we should first test the simplest model by checking the newest set of tree ring widths.
15. Posted Mar 27, 2007 at 4:37 PM | Permalink
Re: 14
Thanks Bernie. As Steve M. has pointed many times in the past, economists face these and other kinds of issues all the time (both the non-experimental nature of most of our data as well as various endogeneity problems. For example, how does one estimate returns to college education when people who go to college choose to go to college because they expect to be better off by making that choice?
How does one deduce temperature sensitivity based on trees which have survived through temperature fluctuations over hundreds of years when the more sensitive trees might have died and not made it to 20th century?
I don’t pretend to have any answers to the latter question, but, at least in the case of returns to education, any economics paper that did not address the inherent bias in the selection process would be ripped to shreds at the working paper stage and I just to not see the same high standards applied to research in the climate reconstruction studies.
I am afraid I have strayed off-topic here so I will shut up :-)
16. Bill F
Posted Mar 27, 2007 at 5:26 PM | Permalink
Thanks Sinan,
With the AMS process, I understand that they take their forecast, and compare it to forecasts from other methods, such as using past climate data from the same period of time…i.e. the model-based prediction for high temperatures on March 28th compared to the average high temperatures for the past 30 march 28ths at the same location. That is their way of saying is our forecast method better (or more “skillful”) than looking out the rear window of the car?
In other words, they aren’t telling you how well they actually predict the weather in an absolute sense…they could be wrong 95% of the time, and they would still be considered “skillful” if the other method was wrong 98% of the time. I would rather see them evaluate skill in an absolute sense, by comparing their forecast to the actual conditions that occur during the forecast period and then telling us how often they were right. That is what I mean by judging skill against real data.
Lets say you and I were each asked to predict the color of the sky before walking out the door, and you said red and I said green. Just because the wavelength of my color was closer to blue than yours wouldn’t mean my prediction was more skillful, because we are both still wrong.
Now I think part of the problem with comparing “forecast skill” to tree-ring based temperature reconstructions is that a reconstruction isn’t really a forecast. You aren’t predicting anything so much as showing that your method of reading the rings is valid and that the ring width is a function of temperature. We already have plenty of temperature data for at least a portion of the time period covered by many tree ring series. Where I disagree with you is where you say we only have one data set. We have at least two. We can have an instrumental set from a nearby station, and we have a set from the trees growing there.
So why can’t the dendroclimatologists first look at the tree rings from say 1900 to 1940 and compare them to the instrumental record to develop a “prediction” of the tree’s response to temperature. Then use the data from 1940 to 1980 or whenever the series ends to test the “skill” of the prediction against the actual instrumental data for that period? If the “prediction” does not accurately predict the actual data, then how can you have any confidence in the ability of it to backforecast to time periods where we have no data? If the tree ring based temperature forecast for any given series doesn’t match the real data where they are growing, how can you say that they will then turn around and accurately show a “global temperature signal” with any level of “skill”? It really seems to be more of a case of taking a random signal and torturing it until you get the shape you want at that point.
It seems like Steve does a great job delving deep into the statistical methodology and going back and showing how random noise series can be input and used to create the same statistical parameters with some of these constructions. But I was really struck by Juckes’ claim that his proxies did not have to match the local records in order to be used in his reconstruction. For me, that shocker points to a far more basic and fundamental problem than how these guys are doing their statistics. It seems to me that if the proxy data doesn’t match the local instrumental data, then it is dead from the start and no amount of statistical manipulation can turn it into a meaningful representation of anything. I appreciate the urge to “update the proxies” and think it is a good idea on the whole, but for lots of locations, there is already nearby real world data to compare the existing proxy data to and apparently guys like Juckes don’t care whether it matches or not. What good will updating the proxy do if they already don’t match the local data and are bing used anyway?
17. Bill F
Posted Mar 27, 2007 at 5:41 PM | Permalink
#15 Sinan,
I totally agree with you about the problems with confounding variables that are essentially unmeasurable. I think I drive my wife crazy when we are riding in the car and a report about a new study comes on the radio. I end up spending several minutes dissecting all of the other possible variables that were not considered as a part of the study.
My favorite one to consider is the idea of telephone opinion polls. Think about how much gets done based on public opinion…and for so long, random dial telephone polling was the standard means to do find out what the public’s opinion was. But if you only called during the day, you were then restricting your view of the public to “people who are home during the day”. Which meant that most likely your subset was made up mostly of four groups…stay at home moms, unemployed people, people who work nights, and kids. But of those subsets, the kids were unlikely to take the poll and the people who worked nights would be trying to sleep and would either not answer the phone or would not take the poll. So most of the polls would really only reflect the opinion of a very tiny subset of the population that was either a stay at home mom or unemployed. Even now that they do more calling at night, they are still only going to get a response from people who are willing to take the time to answer the poll…which to me would likely represent a very specific set of personality types that would assumably bias their survey towards the opinions of people with those particular personality types. If you really sit and puzzle on it long enough, you eventually reach the conclusion that even if you can find a statistically representative number of people willing to take your survey, the bias inherent in the methods alone should cause a great deal of uncertainty in whether the poll actual reflects the opinions of the population it is supposed to represent. I doubt that tree-ring proxies have any lower degree of uncertainty…
18. Bill F
Posted Mar 27, 2007 at 5:46 PM | Permalink
Mark,
My understanding of what the hockey team was doing was taking groups of proxies and comparing them with a glabal data set of temperatures. I was not aware that they ever tried to evaluate the individual proxies against local temperature data before accepting them as valid. I think Steve even specifically pointed out some of their series which were bing used by others as precipitation or ocean current proxies instead of temperature.
19. TAC
Posted Mar 27, 2007 at 6:13 PM | Permalink
Bill F (#17): In case you have not heard of it, a favorite example of a poorly designed telephone poll.
20. Posted Mar 27, 2007 at 6:21 PM | Permalink
Re: 16
Bill, we agree on most points. In fact, one can go one step further. Do the construction using first half of the data set, then predict temperatures using the tree ring widths from the second, and then do a construction using the second half, and predict temperatures using tree ring width data from the first half.
Where I disagree with you is where you say we only have one data set. We have at least two. We can have an instrumental set from a nearby station, and we have a set from the trees growing there.
It is true that one can randomly sample among stations but one cannot randomly sample among temperature observations for a given station. It is in that sense that the data are fixed.
Now, it would be a useful experiment to do the temperature reconstruction using a subset of temperature data and see how much success one has in predicting temperature changes in the other subset.
Potential difficulties (both in concept and implementation) arise from the fairly non-random distribution of where humans have chosen to measure temperature.
A significant problem with these temperature reconstructions is that the sparsity in the most famous literature of any consideration of how their constructions might be falsified.
Sinan
21. Posted Mar 27, 2007 at 6:45 PM | Permalink
Dear Steve,
that’s a very detailed and comprehensive study on the topic of “skill” from the viewpoint of comparative literature. If you forgive me, ;-) I wouldn’t criticize Burger myself.
It is nice to have exact definitions of objects, but on the other hand, it is not always the key physical requirement. Skill is not an objective physical observable: it is a useful concept that helps in your strategy to find the answers to scientific questions and the right theories. Burger clearly wanted to say some universal statements that are independent of the partially cultural details of the exact definition of a skill.
Skill just measures how much more accurate prediction you get from a formula, theory, or model in comparison with a supernaive model such as a constant average. Whether it is worth at all to go to a more complex model. Even if you get some skill, the new complicated model can still be a bad step because the amount of parameters can be too expensive for the small increase in accuracy; the notion of “skill” doesn’t save you from models with too many parameters – do I understand well? The phrase “higher skill” just means “more accurate agreement with the data”.
I don’t quite understand the discussions about the skill of the predictions. Of course that a model has either a low skill or a high skill for its predictions but I think that you can only know what the answer is after the future comes and the predictions can be compared with reality. Or do I misunderstand something?
While I think that Burger doesn’t rely on details of the definition, I think that at various places, they had offered some definitions – so did you, in fact. So if Burger talks about the skill claims by MBH, I think that it is expected that he should use a definition that is as similar to the MBH definition as possible – while obvious errors in it are corrected – and before you find an actual error in his statement, it doesn’t seem justified to criticize him.
Let me return to the first point. I do think that the notion is generally a fluid notion, and if you call for this notion not to be fluid, you contradict one of its basic characteristics. There is no God-given universal skill usable in all situations, but there are still qualitative statements that one can do independently of having an exact definition. People using different conventions should still be able to read the paper which is why I think that a more fluid qualitative treatment of the notion is better.
Of course, the sentences about it must be supported quantitatively, but I think that Burger’s sentences with the word “skill” are qualitative.
BTW the blog page says that there is a 15 minute delay due to caching. I think I know how to circumvent it. Just add some extra arguments to the URL such as … ?p=1301¬hing=000. ;-)
All the best
Lubos
22. John S
Posted Mar 27, 2007 at 7:13 PM | Permalink
In fact, one can go one step further. Do the construction using first half of the data set, then predict temperatures using the tree ring widths from the second, and then do a construction using the second half, and predict temperatures using tree ring width data from the first half.
They do actually do that to a certain extent.
A problem with that approach is that it is very hard to resist peeking at the other data – and once you’ve peeked or done this once the value of the ‘withheld’ data set is gone from a statistical point of view. Thus, for example, there were many studies of money demand in the economics literature that claimed to find robust relationships between activity and money and used exactly the procedure described above. Unfortunately, these all broke down when truly out of sample data became available. In the case of these equations a big problem was the ‘all other things equal’ assumption that turned out to be spectacularly wrong during the financial deregulation of the 1980s.
With respect to tree rings you have similar problems. And these are problems that are inherent in the statistical process. In an ideal world you would run one regression (with the fist half of the data), test it and then publish. In reality people run hundreds of regressions until they find one that works. This is not a problem that is unique to dendroclimatologists. But it means that the only true demonstration of skill is when entirely new data is used to test a hypothesis – regardless of what procedures the researcher claims to have followed with their initial data set. Thus, you need to wait a while and gather additional time series, or go somewhere else and gather new tree rings. But you have to use data that was unavailable to the original researcher – you just can’t help peeking, it’s human nature.
23. Steve McIntyre
Posted Mar 27, 2007 at 7:43 PM | Permalink
#22. The form of split samples is observed in many studies; Juckes is rather an exception. I agree 1000% with John S on the problems with knowing the data sets. People know what the data look like in advance. I successfully predicted over 80% of the proxies selected in Hegerl et al because I expected them to use almost the same proxies as Osborn and Briffa 2006, which they did. I made a prediction in advance of the paper being released, which is up at the blog.
Because many of the tree ring sites were taken up to only 1980, there is actually an ideal opportunity to see how they perform out of sample. That’s why I’m attentive to new data – to see if the ring widths reflect recent warm temperatures. However, there is much evidence that they don’t – hence the “divergence factor”. In any other field , the “divergence” problem would be held to falsify the hypothesis of a linear relatinoship between ring widths and temperature above a threshold – as one would expect from the upside-down quadratic growth curves in botanical studies. One sees data being truncated at 1960 to avoid facing up to this. Briffa’s handling of the divergence problem is a marvel and bears repeating over and over:
In the absence of a substantiated explanation for the decline, we make the assumption that it is likely to be a response to some kind of recent anthropogenic forcing. On the basis of this assumption, the pre-twentieth century part of the reconstructions can be considered to be free from similar events and thus accurately represent past temperature variability.
Of course, when I make these quotes, the tree ring people think I’m being mean to them. I did a detailed report on this issue in http://www.climateaudit.org/?p=529 and showed a wonderful truncation of the Briffa record in IPCC TAR here http://www.climateaudit.org/?p=194 .
24. Posted Mar 27, 2007 at 7:47 PM | Permalink
Re: 22
John S., note that my first post (#12) in this thread pointed out the need for genuine out of sample verification by extending proxies.
Sinan
25. bender
Posted Mar 27, 2007 at 9:34 PM | Permalink
The skill score (SS) is useful for evaluating predictions of temperatures, pressures, or the numerical values of other parameters. It compares a forecaster’s root-mean-squared or mean-absolute prediction errors, Ef, over a period of time, with those of a reference technique, Erefr, such as forecasts based entirely on climatology or persistence, which involve no analysis of synoptic weather conditions: If SS > 0, the forecaster or technique is deemed to possess some skill compared to the reference technique.
SS is a heuristic, not a statistic. Wegman is a statistician, not a heuristician.
26. John S
Posted Mar 27, 2007 at 9:58 PM | Permalink
Sinan,
Not arguing with anything you’ve said – just emphasising a point that I think bears repeating.
27. Posted Mar 27, 2007 at 10:06 PM | Permalink
Dear bender #25, the rather rigorous definition of SS in your comment combined with the opinion that it is just a “heuristic” just don’t seem to fit together too well.
It is perfectly plausible that the statistical community doesn’t use certain semi-scientific semi-conventional measures of validity of a model but this fact itself doesn’t imply that these methods are scientifically flawed.
I am sure that many other fields are using statistical methods that are unfamiliar to 99+ percent of statisticians. My guess is that the statistical machines used to evaluate data from experimental particle physics or the WMAP variations would sound unfamiliar to most statisticians in many respects, and these statisticians would struggle for some time before they could accept them.
And if I can be frank, I think that experimental particle physicists who deal with the events are way better statisticians than statisticians.
But anyway, these methods work and allow physicists to test standard theories and sometimes find new phenomena. Statisticians are just not experienced with certain kinds of tasks even though their nature is statistical. I would discourage everyone from criticizing others for using certain methods just because you’re not used to these methods unless you are able to prove that they lead to wrong conclusions or results.
28. fFreddy
Posted Mar 28, 2007 at 12:12 AM | Permalink
Re #27, Lubos
What do you mean by “statistical machines” ?
And surely the experimental particle physicists have written up and justified any new techniques they might have developed ?
29. Posted Mar 28, 2007 at 12:42 AM | Permalink
#27
I am sure that many other fields are using statistical methods that are unfamiliar to 99+ percent of statisticians.
That is true. But often those methods are flawed, specially if the experiments cannot be controlled / repeated, and the observed responses are barely detectable. ‘we must be able to explain it all’ mentality kicks in, and statistics are exploited.
And if I can be frank, I think that experimental particle physicists who deal with the events are way better statisticians than statisticians.
I don’t think so. Very often they suffer i.i.d syndrome :)
I would discourage everyone from criticizing others for using certain methods just because you’re not used to these methods unless you are able to prove that they lead to wrong conclusions or results.
I agree. Quite often the methods are the very same methods that statisticians use, but with different terminology.
30. John S
Posted Mar 28, 2007 at 12:51 AM | Permalink
Re #27
Generally speaking, the expermiental sciences don’t need to deal with leading-edge statistics. They can construct their experiments to provide good quality data where external factors are held constant and proper sampling can be done. It’s the non-experimental sciences – with economics being the prime example – where you need to be really careful with your statistics and a lot of statistical innovation happens. If your data is crappy (statistically speaking) and you can’t get better data, you do the best you can with that data – econometrics excels at identifying the robust conclusions that can be made from poor quality data. In the expermiental sciences you try to get better data – in economics you have to get better statistics.
31. fFreddy
Posted Mar 28, 2007 at 1:23 AM | Permalink
Re #29, UC
I agree with this bit :
I would discourage everyone from criticizing others for using certain methods just because you’re not used to these methods …
I don’t like this bit :
I would discourage everyone from criticizing others for using certain methods … unless you are able to prove that they lead to wrong conclusions or results.
which sounds a bit Mannian.
The interim step needs to be a detailed justification of the new method, I would have thought.
32. MarkW
Posted Mar 28, 2007 at 5:12 AM | Permalink
Bill F,
Regarding phone polls, people who don’t have a landline (ie, cellphones only) don’t get polled at all.
33. bernie
Posted Mar 28, 2007 at 5:18 AM | Permalink
Lubos
I would discourage everyone from criticizing others for using certain methods just because you’re not used to these methods unless you are able to prove that they lead to wrong conclusions or results.
I agree but with the following caveat. Researchers should be free to choose the statistical methods that reflect the nature of the data that is being analyzed and the question being asked. I think the common ground needs to be using methods that have well defined assumptions and well defined limitations that are articulated in a statistics/methods reference (as opposed to simply citing another “successful” user of the same techniques). I noted with interest Steve picking up on a statistical point in Burger and arguing that the point needed appropriate citations. The challenge in fields like climatology is that those interested in the results come from a wide array of fields and, therefore, there is a responsibility on the part of climatologists to provide references for what might appear to be SOP statistical practices in the field but which are in fact discipline specific procedures. Highly specialized fields like particle physics may well “get away with” evolving their own statistical tools until it comes to the point where their conclusions require public policy decisions. Then they will have the responsibility of making their methods and tools more transparent to “skilled” laymen. It is the price of relevance and/or notoriety.
Yet another reason for having statisticians review articles that involve statistical analysis.
34. Willis Eschenbach
Posted Mar 28, 2007 at 5:57 AM | Permalink
Lubos, your posts are always thought provoking. However, I must respectfully disagree when you say:
I would discourage everyone from criticizing others for using certain methods just because you’re not used to these methods unless you are able to prove that they lead to wrong conclusions or results.
This is Alice in Wonderland science.
Alice laughed, “There’s no use trying,” she said, “one can’t believe impossible things.”
“I daresay you haven’t had much practice,” said the Queen. “When I was your age, I always did it for half-an-hour a day. Why, sometimes I’ve believed as many as six impossible [statistical procedures] before breakfast.”
The onus is not on us to believe six new statistical methods before breakfast, or to show that some novel, unusual statistical procedure doesn’t work. The onus is on the dendrochrologists to show that it does work, that is some theoretical justification for the procedure, and their conclusions should be discarded until such substantiation is forthcoming.
w.
35. bender
Posted Mar 28, 2007 at 6:21 AM | Permalink
the rather rigorous definition of SS in your comment combined with the opinion that it is just a “heuristic” just don’t seem to fit together too well.
Heuristics can be complex and they can be “rigorous” in their definition. That doesn’t mean a network of statisticians is likely to have heard of them. I’m not dismissing SS, or any heuristic. I’m explaining how gaps in knowledge between disciplines can arise. Creativity in isolation is how it happens. And this is the mark of art, not science.
36. Posted Mar 28, 2007 at 7:54 AM | Permalink
Dear fFreddy, by statistical machines, I mean a whole framework of statistical concepts, algorithms, conventions, exceptions, rules how to choose which sub-method should be used, and criteria to determine whether the results are trustworthy.
And surely the experimental particle physicists have written up and justified any new techniques they might have developed?
I just think you wouldn’t be satisfied. The colliders, for example, deal with a huge number of events (colissions that produce new particles with particular properties) per second and it is impossible to store data about each of them. Most of them must be thrown away. The events that are used to deduce physics are only an “interesting subset”. The discarded events are “uninteresting” and they are counted as following a boring background. Quite clearly, there is a lot of conventions one must pick in dividing the events into the interesting and uninteresting ones in the first place, and understanding physics is a key to do it right.
After you do it, you end up with the interesting events but there is no 100% reliable way to reconstruct what happened in a particular event. (In fact, this question can’t be answered even in principle because amplitudes from all possible processes with the same initial and final state contribute to a given event.) Many different types of events – e.g. with new intermediate particles – have signals that overlap with each other but give different patterns of signals, hopefully. Some of the signals are known, some of them are not because they are “new physics”. One must be able to choose a cut that defines the number of jets in an event – a jet is a stream of many particles going in a “similar” (…) direction, resulting from a quark or gluon that was in the middle.
There is no canonical method to do these things. In fact, there are many systems of conventions and approaches. Also, there are many event simulators, and they differ in profound technical details. You can’t justify one over the other by a universal argument. You must allow them to co-exist and only if one of them turns out to give systematically more useful and accurate results, it will be preferred. Everything must be allowed to compete: not only experimental teams and theories but also statistical strategies. Which of the event simulator strategies will be the winner in the future doesn’t depend on statistics only. It depends on the laws of physics, and some of them are not yet known or not yet properly understood as far as their consequences go.
I am sure you must have heard this from many alarmists already, but I certainly agree with whoever has said that science is not just statistics, and the best choice of statistical methods to study Nature may depend on the laws of physics, not just some universal statistical rules and dogmas.
It is also untrue that statisticians are necessarily guaranteed to be the best people for everything that has the word “statistics” in it, just like climatologists are not necessarily the best choice to solve anything with the word “climate” in it. The expectation whether someone does things right and takes the most important things into account depends on the intelligence and training of the person, and similarity to other tasks he has solved in the past.
I am really sorry to say the same thing as Mann but it’s true. ;-) Now, Mann was almost certainly wrong in most of his statements about the past hockey climate, which makes the work unusable, but you can’t prove he was wrong just because he is not a statistician. The whole concept of competing professions who have the right to keep ownership over their topics is completely silly. If someone else does things better than a “clique” in a field, he is just doing it better.
If string theorists become better in predicting nuclear scattering experiments than the people who learned nuclear physics for decades, what can you do about it? ;-) It is pretty likely that it is going to happen. There are many examples like that. Outsiders with sufficient talents and hard work can do things that the insiders can’t. They can be patent clerks or mining consultants and their way of talking about scientific questions doesn’t have to fit the box of a horde mentality, but this itself doesn’t prove that they’re wrong.
Dear Willis #34, I completely agree that in order for a method to have any value, one must show that it works. I don’t know why you think I disagree. ;-) But before you prove that it works, you must try whether it works. :-)
Bender #35, this is just terminological issue but you’re just wrong if you say that heuristics can be rigorous. Internally they can be rigorous but they’re certainly not rigorous as a description what they want to describe, by definition. Heuristics are tools to direct our attention in the hopefully right direction. And again, I don’t think that the observations “network of statisticians hasn’t heard about XY” proves that XY is wrong.
37. Posted Mar 28, 2007 at 8:10 AM | Permalink
OK, let me mention one more thing about this general question of presumption of innocence. I actually disagree with the rule that we must always assume that everything is wrong unless it is rigorously proven, or something like that.
Another word to describe this approach is bias it and can’t be used consistently with the laws of logic. If a person writes a non-rigorous paper asserting “A”, someone else can write a non-rigorous paper asserting “non A”. You can’t assume that both of these papers are wrong just because you should always assume that non-rigorous papers are wrong – because it would be logically inconsistent.
I think that the only scientific approach is to admit “I don’t know” at the beginning and judge various statements fairly regardless whether they are formulated as “positive” statements or “negative” statements – which is a matter of presentation not science, after all. Saying that one must always assume something about a certain result formulated in a certain way is bad. Assuming that a paper must be wrong is as irrational as assuming that a paper must be right.
Of course that until sufficient evidence is given for a statement or a paper, a rational person won’t take it seriously. A rational person will continue to think that “we don’t know”. But saying that it must be wrong just because it appears in a paper that is not rigorous is simply irrational. Even non-rigorous work can lead to a systematic improvement of our knowledge, and in most fields it does as long as the signal is stronger than the noise where noise includes not only uncontrollable fluctuations but also fraud and ideologically-driven selection bias.
38. Steve McIntyre
Posted Mar 28, 2007 at 8:14 AM | Permalink
I don’t think that the observations “network of statisticians hasn’t heard about XY” proves that XY is wrong.
I think that, for the most part, most of us are on the same page here, although we may be expressing it in different ways. My instinct when I see discussions of “statistical skill” is to see if that is isomorphic to some statistical concept with which I (or Wegman) might be familiar – in the same way that I don’t throw up my hands because someone calls what I would call an “eigenvector” an “empirical orthogonal function” or “principal mode” or something like that.
Von Storch has observed to me quite fairly that most statisticians don’t really bring much to the party as they typically arrive with i.i.d. baggage and try to force the problems into a mold that doesn’t apply. I thnk that econometricians and even business statisticians are, in some ways, more useful because they are used to autocorrelated series and have different instincts than an i.i.d. statistician.
When one is dealing with the Team, I get the sense of people using big words pompously or people trying to fit the facts to the policy without inquiring into what could be wrong with their model rather than practical people soberly viewing their data.
Let’s suppose that we grant weather forecasters their use of “skill” as a useful concept in eveluating weather forecasting systems. The question then is whether this vocabulary with its metaphorical baggage is a more useful way of approaching paleoclimate reconstructions. Thinking some more about it, I see one huge difference – the weather forecasting models are physics-based, even if there is a lot of parameterization in them and they actually do get tested on out-of-sample data. So one can see how the term “skill” can have real meaning in a practical sense. When one is making a climate reconstruction from dendro site chronologies, we do not have a physics-based link between ring widths and temperature – we have curve fitting in a calibration period. I think that the enterprise is much more in the style of statistical modeling than it is to weather forecasting.
Thinking about it a little more,
39. Tom Vonk
Posted Mar 28, 2007 at 8:59 AM | Permalink
Outsiders with sufficient talents and hard work can do things that the insiders can’t. They can be patent clerks or mining consultants and their way of talking about scientific questions doesn’t have to fit the box of a horde mentality, but this itself doesn’t prove that they’re wrong.
I like that .
Actually I even think that the more complex a field is the more chance an outsider has to shed some light in it because he is still able to ask simple , relevant questions .
I have a friend who is expert in the string theory and he told me that the guy who will find one day the way out of this mess will almost certainly be somebody who has not a clue in string theory and who will ask the right question about the gravity and quantum mechanics .
Somebody I forgot has said that it is better to bring wrong answers to relevant questions than to bring right answers to irrelevant questions .
40. bernie
Posted Mar 28, 2007 at 9:48 AM | Permalink
Tom:
Sounds like Feynmann!!
41. Ken Fritsch
Posted Mar 28, 2007 at 9:57 AM | Permalink
Re: #38
Thinking some more about it, I see one huge difference – the weather forecasting models are physics-based, even if there is a lot of parameterization in them and they actually do get tested on out-of-sample data. So one can see how the term “skill” can have real meaning in a practical sense. When one is making a climate reconstruction from dendro site chronologies, we do not have a physics-based link between ring widths and temperature – we have curve fitting in a calibration period. I think that the enterprise is much more in the style of statistical modeling than it is to weather forecasting.
You have summarized my thoughts on the subject nearly exactly. Without out-of-sample results be careful of what and how you conclude, be very careful. Heck, you should even be careful of how you conclude using out-of-sample results.
And a statistic used more or less exclusively in your community or invented in your community should not be considered merely a convenient term for community discussions, it should either have statistical rigor or be redefined as a part of your community terminology and without statistical implications.
42. Mark T.
Posted Mar 28, 2007 at 9:59 AM | Permalink
or “principal mode” or something like that.
Interestingly, the concept of “modes” is rather common in the signal processing community. At least, the SIGINT guy I used to work with (before I got this shiny new job) referred to eigenvalue decompositions as dominant mode analysis. I was explaining the Gram-Schmidt process I was working with (uh, a sort of PCA method, btw) and he kept mentioning that I was “finding the dominant modes” (he also kept bringing up “Householder rotations”). It was a term I was unfamiliar with, but nevertheless meant exactly what I was addressing.
Mark
43. DocMartyn
Posted Mar 28, 2007 at 6:49 PM | Permalink
O.K. This might sound a bit odd, but has anyone ever looked at the tree rings in Central Park, NY or other Parks where mature trees have been MOVED. Large living trees have been moved from all over in Parks in the US and UK. There will be records of where the trees were dug up from and when they were moved and planted.
What happens to tree ring growth whene you move it into the center of a heat Island? The trees in Cental Park will be a lot warmer than almost anywhere in 200 miles, surely that should give you some signal. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 1, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5974434018135071, "perplexity": 973.0421000871885}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-07/segments/1454701160582.7/warc/CC-MAIN-20160205193920-00108-ip-10-236-182-209.ec2.internal.warc.gz"} |
http://kumpulanrangkaianelektronik.blogspot.com/2012/03/rangkaian-pengukur-kecepatan-udaran.html | Wednesday, 14 March 2012
Rangkaian Pengukur Kecepatan Udaran
Skema rangkaian pengukur kecepatan udaran
This is a simple wind meter (anemometer) circuit. this circuit can measure wind speeds up to 75m/s using this circuit.
Transistors Q1 and Q2 are used for sensing the wind. The relationship between thermal impedance of the transistor and the surrounding wind speed is utilized here. Transistors Q1 and Q2 are wired so that
the Vce of Q1 is higher than Q2 and therefore there will be a higher power dissipation. The wind causes cooling and so the Vce of Q1 changes. The ends in different power dissipations and different voltages across R10. This variation is detected by the opamp and amplified to produce the Vout which is proportional to the wind speed. For still air Vout will be 0V and at 75m/s wind speed the Vout will be 2.5V. A 3V FSD voltmeter connected across the Vout terminal and ground can be used as the display.
For proper working, the air must pass over both the transistors (Q1 and Q2).
The resistors used are not standard values. So you need to use the combination (series or parallel) of resistors to attain the specified values. Please note that the resistor values are very critical in this circuit.
IC LT1013 Description
Absolute maximum ratings IC LT1013
• Supply voltage : . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . +22 V/ –22 V
• Input voltage range, VI (any input) . . . . . . . . . . . . . . . . . . .. . . VCC– –5 V to VCC+
• Differential input voltage . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 30 V
• Duration of short-circuit current at (or below) 25 C . . . . . . . . . . Unlimited
• Package thermal impedance, θJA : D package . . . . . . . . . . . . 97 C/W
• P package . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 85 C/W
• Case temperature for 60 seconds: FK package . . . . . . . . . . . . 260 C
• Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds: D or P package . . . . 260 C
• JG package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 C
• Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . .. . . –65 C to 150 C | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9764888882637024, "perplexity": 245.2557715713952}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1408500823333.10/warc/CC-MAIN-20140820021343-00122-ip-10-180-136-8.ec2.internal.warc.gz"} |
https://hal.archives-ouvertes.fr/hal-00338401/ | # A connection between extreme value theory and long time approximation of SDE's
Abstract : We consider a sequence $(\xi_n)_{n\ge1}$ of $i.i.d.$ random values living in the domain of attraction of an extreme value distribution. For such sequence, there exists $(a_n)$ and $(b_n)$, with $a_n>0$ and $b_n\in\ER$ for every $n\ge 1$, such that the sequence $(X_n)$ defined by $X_n=(\max(\xi_1,\ldots,\xi_n)-b_n)/a_n$ converges in distribution to a non degenerated distribution. In this paper, we show that $(X_n)$ can be viewed as an Euler scheme with decreasing step of an ergodic Markov process solution to a SDE with jumps and we derive a functional limit theorem for the sequence $(X_n)$ from some methods used in the long time numerical approximation of ergodic SDE's.
Mots-clés :
Type de document :
Article dans une revue
Stochastic Processes and their Applications, Elsevier, 2009, 119 (10), pp.3583-3610
Domaine :
Littérature citée [12 références]
https://hal.archives-ouvertes.fr/hal-00338401
Contributeur : Fabien Panloup <>
Soumis le : jeudi 13 novembre 2008 - 09:51:12
Dernière modification le : vendredi 21 octobre 2011 - 07:37:13
Document(s) archivé(s) le : lundi 7 juin 2010 - 21:21:32
### Fichiers
article_extreme_value.pdf
Fichiers produits par l'(les) auteur(s)
### Identifiants
• HAL Id : hal-00338401, version 1
• ARXIV : 0811.2052
### Citation
Fabien Panloup. A connection between extreme value theory and long time approximation of SDE's. Stochastic Processes and their Applications, Elsevier, 2009, 119 (10), pp.3583-3610. 〈hal-00338401〉
Consultations de
la notice
## 146
Téléchargements du document | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8838251233100891, "perplexity": 1797.4594965484428}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-39/segments/1505818696182.97/warc/CC-MAIN-20170926141625-20170926161625-00605.warc.gz"} |
http://math.andrej.com/2009/04/09/pythons-lambda-is-broken/?replytocom=11491 | # Python’s lambda is broken!
I quite like Python for teaching. And people praise it for the lambda construct which is a bit like $\lambda$-abstraction in functional languages. However, it is broken!
To see how lambda is broken, try generating a list of functions $[f_0, …, f_9]$ where $f_i(n) = i + n$. First attempt:
>>> fs = [(lambda n: i + n) for i in range(10)]
>>> fs[3](4)
13
Wait a minute, fs[3](4) ought to be 3 + 4 = 7! It looks like all 10 functions share the same “last” value of i, which is 9. Indeed:
>>> [f(4) for f in fs]
[13, 13, 13, 13, 13, 13, 13, 13, 13, 13]
This is certainly unexpected. Let us try to get around the problem by not using lambda:
>>> fs = []
>>> for i in range(10):
... def f(n): return i+n
... fs.append(f)
...
>>> [f(4) for f in fs]
[13, 13, 13, 13, 13, 13, 13, 13, 13, 13]
Still not working, so the reason is deeper, probably in the way environments are handled. Maybe like this:
>>> fs = []
>>> for i in range(10):
... def f(n, i=i): return i+n
... fs.append(f)
...
>>> [f(4) for f in fs]
[4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
Victory! But try explaining to students what is going on.
Just to be sure, Haskell does the right thing, of course!
Prelude> let fs = [(\n -> i + n) | i <- [0..9]]
Prelude> [f(4) | f <- fs]
[4,5,6,7,8,9,10,11,12,13]
What were the implementors of Python thinking?!
## 57 thoughts on “Python’s lambda is broken!”
1. @Aaron: yes, I think someone else pointed out a similar solution. But really, that doesn’t clarify anything. It’s a workaround. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6207396388053894, "perplexity": 2791.895479730024}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-22/segments/1526794868132.80/warc/CC-MAIN-20180527072151-20180527092151-00319.warc.gz"} |
https://www.aimsciences.org/article/doi/10.3934/jimo.2019100?viewType=html | # American Institute of Mathematical Sciences
doi: 10.3934/jimo.2019100
## Robust stochastic optimization with convex risk measures: A discretized subgradient scheme
1 School of Statistics and Mathematics, Shanghai Lixin University of Accounting and Fiance, China 2 School of Mathematical Science, Chongqing Normal University, China 3 Faculty of Science and Engineering, Curtin University, Perth, Australia
* Corresponding author
Received March 2018 Revised July 2018 Published September 2019
Fund Project: This work is partially supported by Grants 11401384, 11671029, 71631008 and B16002 of National Natural Science Foundation of China and by Grant DP160102819 of Australian Research Council.
We study the distributionally robust stochastic optimization problem within a general framework of risk measures, in which the ambiguity set is described by a spectrum of practically used probability distribution constraints such as bounds on mean-deviation and entropic value-at-risk. We show that a subgradient of the objective function can be obtained by solving a finite-dimensional optimization problem, which facilitates subgradient-type algorithms for solving the robust stochastic optimization problem. We develop an algorithm for two-stage robust stochastic programming with conditional value at risk measure. A numerical example is presented to show the effectiveness of the proposed method.
Citation: Haodong Yu, Jie Sun. Robust stochastic optimization with convex risk measures: A discretized subgradient scheme. Journal of Industrial & Management Optimization, doi: 10.3934/jimo.2019100
##### References:
show all references
##### References:
parameters of the test problem
$w$(Wrench) $p$(Plier) $x$: Steel A(lbs.) 1.5 1 $y$: Steel B(lbs.) 1 2 Molding Machine (hours) 1 1 Assembly Machine (hours) .3 .5 Contribution to Earnings (＄/1000 units) 130 100
$w$(Wrench) $p$(Plier) $x$: Steel A(lbs.) 1.5 1 $y$: Steel B(lbs.) 1 2 Molding Machine (hours) 1 1 Assembly Machine (hours) .3 .5 Contribution to Earnings (＄/1000 units) 130 100
combined distribution of $h$
$h_2$ $h_1$ 21000 25000 8000 0.25 0.25 10000 0.25 0.25
$h_2$ $h_1$ 21000 25000 8000 0.25 0.25 10000 0.25 0.25
possible values of h
$i$ 1 2 3 4 $h_{1i}$ 21000 21000 25000 25000 $h_{2i}$ 8000 10000 8000 10000
$i$ 1 2 3 4 $h_{1i}$ 21000 21000 25000 25000 $h_{2i}$ 8000 10000 8000 10000
production plans under various scenarios
$i$ 1 2 3 4 $w_i$ 7988 9969 8000 9969 $p_i$ 77 10 27 10
$i$ 1 2 3 4 $w_i$ 7988 9969 8000 9969 $p_i$ 77 10 27 10
worst-case distribution of $h$
Pro 0.5 0.0134 0.0539 0.0006 0.4321 $h_1$ 22355 22216 21008 22239 24021 $h_2$ 8000 10000 10000 10000 10000
Pro 0.5 0.0134 0.0539 0.0006 0.4321 $h_1$ 22355 22216 21008 22239 24021 $h_2$ 8000 10000 10000 10000 10000
[1] Ripeng Huang, Shaojian Qu, Xiaoguang Yang, Zhimin Liu. Multi-stage distributionally robust optimization with risk aversion. Journal of Industrial & Management Optimization, 2017, 13 (5) : 0-0. doi: 10.3934/jimo.2019109 [2] Bin Li, Jie Sun, Honglei Xu, Min Zhang. A class of two-stage distributionally robust games. Journal of Industrial & Management Optimization, 2019, 15 (1) : 387-400. doi: 10.3934/jimo.2018048 [3] Chien Hsun Tseng. Applications of a nonlinear optimization solver and two-stage comprehensive Denoising techniques for optimum underwater wideband sonar echolocation system. Journal of Industrial & Management Optimization, 2013, 9 (1) : 205-225. doi: 10.3934/jimo.2013.9.205 [4] Yufei Sun, Grace Aw, Kok Lay Teo, Guanglu Zhou. Portfolio optimization using a new probabilistic risk measure. Journal of Industrial & Management Optimization, 2015, 11 (4) : 1275-1283. doi: 10.3934/jimo.2015.11.1275 [5] Zhiping Chen, Youpan Han. Continuity and stability of two-stage stochastic programs with quadratic continuous recourse. Numerical Algebra, Control & Optimization, 2015, 5 (2) : 197-209. doi: 10.3934/naco.2015.5.197 [6] Jingzhi Li, Hongyu Liu, Qi Wang. Fast imaging of electromagnetic scatterers by a two-stage multilevel sampling method. Discrete & Continuous Dynamical Systems - S, 2015, 8 (3) : 547-561. doi: 10.3934/dcdss.2015.8.547 [7] Xi Chen, Zongrun Wang, Songhai Deng, Yong Fang. Risk measure optimization: Perceived risk and overconfidence of structured product investors. Journal of Industrial & Management Optimization, 2019, 15 (3) : 1473-1492. doi: 10.3934/jimo.2018105 [8] Tugba Sarac, Aydin Sipahioglu, Emine Akyol Ozer. A two-stage solution approach for plastic injection machines scheduling problem. Journal of Industrial & Management Optimization, 2017, 13 (5) : 0-0. doi: 10.3934/jimo.2020022 [9] Jutamas Kerdkaew, Rabian Wangkeeree. Characterizing robust weak sharp solution sets of convex optimization problems with uncertainty. Journal of Industrial & Management Optimization, 2017, 13 (5) : 1-23. doi: 10.3934/jimo.2019074 [10] Igor Griva, Roman A. Polyak. Proximal point nonlinear rescaling method for convex optimization. Numerical Algebra, Control & Optimization, 2011, 1 (2) : 283-299. doi: 10.3934/naco.2011.1.283 [11] Nobuko Sagara, Masao Fukushima. trust region method for nonsmooth convex optimization. Journal of Industrial & Management Optimization, 2005, 1 (2) : 171-180. doi: 10.3934/jimo.2005.1.171 [12] René Henrion, Christian Küchler, Werner Römisch. Discrepancy distances and scenario reduction in two-stage stochastic mixed-integer programming. Journal of Industrial & Management Optimization, 2008, 4 (2) : 363-384. doi: 10.3934/jimo.2008.4.363 [13] Rüdiger Schultz. Two-stage stochastic programs: Integer variables, dominance relations and PDE constraints. Numerical Algebra, Control & Optimization, 2012, 2 (4) : 713-738. doi: 10.3934/naco.2012.2.713 [14] Chao Mi, Jun Wang, Weijian Mi, Youfang Huang, Zhiwei Zhang, Yongsheng Yang, Jun Jiang, Postolache Octavian. Research on regional clustering and two-stage SVM method for container truck recognition. Discrete & Continuous Dynamical Systems - S, 2019, 12 (4&5) : 1117-1133. doi: 10.3934/dcdss.2019077 [15] Ming-Yong Lai, Chang-Shi Liu, Xiao-Jiao Tong. A two-stage hybrid meta-heuristic for pickup and delivery vehicle routing problem with time windows. Journal of Industrial & Management Optimization, 2010, 6 (2) : 435-451. doi: 10.3934/jimo.2010.6.435 [16] Han Yang, Jia Yue, Nan-jing Huang. Multi-objective robust cross-market mixed portfolio optimization under hierarchical risk integration. Journal of Industrial & Management Optimization, 2020, 16 (2) : 759-775. doi: 10.3934/jimo.2018177 [17] Jian Gu, Xiantao Xiao, Liwei Zhang. A subgradient-based convex approximations method for DC programming and its applications. Journal of Industrial & Management Optimization, 2016, 12 (4) : 1349-1366. doi: 10.3934/jimo.2016.12.1349 [18] Dan Li, Li-Ping Pang, Fang-Fang Guo, Zun-Quan Xia. An alternating linearization method with inexact data for bilevel nonsmooth convex optimization. Journal of Industrial & Management Optimization, 2014, 10 (3) : 859-869. doi: 10.3934/jimo.2014.10.859 [19] Foxiang Liu, Lingling Xu, Yuehong Sun, Deren Han. A proximal alternating direction method for multi-block coupled convex optimization. Journal of Industrial & Management Optimization, 2019, 15 (2) : 723-737. doi: 10.3934/jimo.2018067 [20] Alireza Goli, Hasan Khademi Zare, Reza Tavakkoli-Moghaddam, Ahmad Sadeghieh. Application of robust optimization for a product portfolio problem using an invasive weed optimization algorithm. Numerical Algebra, Control & Optimization, 2019, 9 (2) : 187-209. doi: 10.3934/naco.2019014
2018 Impact Factor: 1.025
## Tools
Article outline
Figures and Tables | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.40642306208610535, "perplexity": 8172.757763646088}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585371611051.77/warc/CC-MAIN-20200405213008-20200406003508-00247.warc.gz"} |
http://www.maa.org/programs/faculty-and-departments/classroom-capsules-and-notes?device=desktop | # Classroom Capsules and Notes
Capsules By Courses. We are organizing the capsules into courses, when possible using the same topics as are used in Course Communities. So far we have organized capsules for the following courses:
• One-Variable Calculus
• Sequences and Series
• Multivariable Calculus
• Ordinary Differential Equations
• Number Theory
• Probability
Select Browse, then select the course in which you are interested. You may select topics within that course.
Notes: Sequences and Series is part of One-Variable Calculus. We felt that since this topic had so many capsules associated with it, we wanted to introduce sub-topics. Also, the Number Theory collection of capsules does not correspond to a course in Course Communities, but has topics selected by the Editorial Board for Classroom Capsules and Notes.
New: The Mathematics of Planet Earth 2013 Collection is now available. These are articles published in the three journals of the MAA that are related to the Mathematics of Planet Earth 2013 theme.
## Featured Items
##### A Classroom Approach to Involutions
Elementary examples from college algebra illustrate the idea of involutions.
##### Applications of Transformations to Numerical Integration
The authors discuss the evaluation of certain improper integrals by first transforming them.
##### Bernstein's Examples on Independent Events
When the sample space is too small, then Bernstein's examples on independent events fail.
##### On the Sum of Consecutive $$K$$th Powers
The author provides a direct and elementary proof of the Bernoulli formula for the sum of consecutive $$K$$th powers.
##### Power Series Expansions for Trigonometric Functions via Solutions to Initial Value Problems
Using initial value problem with repeated differentiations, the author obtains the complicated coefficients of the power series for powers of the secant function.
##### Dogs Don't Need Calculus
The authors use inequalities to solve optimization problems without resorting to calculus, as illustrated by four common examples in calculus. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7760437726974487, "perplexity": 1982.6676943764326}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386163046758/warc/CC-MAIN-20131204131726-00073-ip-10-33-133-15.ec2.internal.warc.gz"} |
http://www.ck12.org/arithmetic/Scientific-Notation-Values/lesson/Scientific-Notation-Values/r7/ | <meta http-equiv="refresh" content="1; url=/nojavascript/">
You are viewing an older version of this Concept. Go to the latest version.
# Scientific Notation Values
%
Progress
Practice Scientific Notation Values
Progress
%
Scientific Notation Values
Have you ever tried to write a number in scientific notation? Evan has a dilemma. Take a look.
Evan is trying to work on his math homework. He is faced with a dilemma where he is being asked to write a number in scientific notation. Here is the number.
$.000000987$
Evan isn't sure how to do this. Do you know?
This Concept is all about scientific notation. By the end of it, you will know how to help Evan with this dilemma.
### Guidance
What is scientific notation?
Scientific Notation is a shortcut for writing numbers and decimals.
When you write in scientific notation, you write decimals times the power of ten that the decimal was multiplied by. You could think of scientific notation as working backwards from multiplying decimals by powers of ten.
$4500 = 45 \times 10^2$
This problem has a whole number and not a decimal. We start with a number called 4500, this has two decimal places in it. Therefore, we are going to say that if we multiplied 45 by 10 squared, we would have 4500 as our number.
Whole number scientific notation has positive exponents. What about decimal scientific notation?
$.0023 = 2.3 \times 10^{-3}$
What does this mean?
It means that to write the decimal, we had to multiply this decimal by a power of ten that is negative because our decimal had to move three places to the right to become a whole number with additional decimal places. When we write a decimal in scientific notation, we use negative exponents. Our number isn’t negative, but the direction that we move the decimal point is represented by negative exponents.
.00056
If we want to write this in scientific notation, we first start with the decimal. This decimal becomes 5.6.
5.6 $\times$ _____
We want to multiply 5.6 by a power of ten. Since this is a decimal, we know that it will be a negative power of ten. Since we moved the decimal point four places, it will be a negative four exponent.
$5.6 \times 10^{-4}$
We can work the other way around too. If we have the scientific notation, we can write the decimal.
$3.2 \times 10^{-5} = .000032$
Scientific notation is very useful for scientists, mathematicians and engineers. It is useful in careers where people work with very large or very small decimals.
Practice writing a few of these decimals in scientific notation.
#### Example A
.0012 = _____
Solution: $1.2 \times 10^{-3}$
#### Example B
.00078 = _____
Solution: $7.8 \times 10^{-4}$
#### Example C
.0000023 = _____
Solution: $2.3 \times 10^{-6}$
Now back to Evan. Here is the original problem once again.
Evan is trying to work on his math homework. He is faced with a dilemma where he is being asked to write a number in scientific notation. Here is the number.
$.000000987$
To write this in scientific notation, we first need to look at which way we are going to move the decimal point. Because this is a very tiny decimal, we are going to move the decimal point to the right. We are going to move it 7 places.
$9.87$
But wait a minute! We aren't done yet. We have to add in the power to show how many places we moved the decimal point.
$9.87 \times 10^{-7}$
### Vocabulary
Power of ten
10, 100, 1000, 10,000 - you can think of them as multiples of ten.
Scientific notation
a way to write decimals and numbers by writing a number sentence that shows a power of ten using an exponent.
Remember:
Multiplying by a power of ten with a positive exponent means the decimal point was moved to the right.
Multiplying by a power of ten with a negative exponent means the decimal point was moved to the left.
### Guided Practice
Here is one for you to try on your own.
Write the following decimal in scientific notation.
$.0000000034$
First, we are going to move the decimal point 9 places to the right.
$3.4$
Next, we add in the power. Notice that the exponent is negative because we moved the decimal to the right.
$3.4 \times 10^{-9}$
### Practice
Directions: Write each decimal in scientific notation.
1. .00045
2. .098
3. .00003
4. .000987
5. .000034
6. .0000021
7. .000000123
8. .00000000345
9. .00056
10. .0098
11. .024
12. .000023
13. .00000043
14. .0000000000128
15. .00000000000098
16. .00000045
### Vocabulary Language: English
Scientific Notation
Scientific Notation
Scientific notation is a means of representing a number as a product of a number that is at least 1 but less than 10 and a power of 10. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 15, "texerror": 0, "math_score": 0.9373933672904968, "perplexity": 707.0121643888684}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207927843.59/warc/CC-MAIN-20150521113207-00266-ip-10-180-206-219.ec2.internal.warc.gz"} |
http://www.maa.org/publications/maa-reviews/the-em-algorithm-and-extensions | # The EM Algorithm and Extensions
###### Geoffrey J. McLachlan and Thriyambakam Krishnan
Publisher:
John Wiley
Publication Date:
2008
Number of Pages:
359
Format:
Hardcover
Edition:
2
Series:
Wiley Series in Probability and Statistics
Price:
100.00
ISBN:
9780471201700
Category:
Monograph
We do not plan to review this book.
Preface to the Second Edition.
Preface to the First Edition.
List of Examples.
1. General Introduction.
1.1 Introduction.
1.2 Maximum Likelihood Estimation.
1.3 Newton-Type Methods.
1.4 Introductory Examples.
1.5 Formulation of the EM Algorithm.
1.6 EM Algorithm for MAP and MPL Estimation.
1.7 Brief Summary of the Properties of EM Algorithm.
1.8 History of the EM Algorithm.
1.9 Overview of the Book.
1.10 Notations.
2. Examples of the EM Algorithm.
2.1 Introduction.
2.2 Multivariate Data with Missing Values.
2.3 Least Square with the Missing Data.
2.4 Example 2.4: Multinomial with Complex Cell Structure.
2.5 Example 2.5: Analysis of PET and SPECT Data.
2.6 Example 2.6: Multivariate t-Distribution (Known D.F.).
2.7 Finite Normal Mixtures.
2.8 Example 2.9: Grouped and Truncated Data.
2.9 Example 2.10: A Hidden Markov AR(1) Model.
3. Basic Theory of the EM Algorithm.
3.1 Introduction.
3.2 Monotonicity of a Generalized EM Algorithm.
3.3 Monotonicity of a Generalized EM Algorithm.
3.4 Convergence of an EM Sequence to a Stationary Value.
3.5 Convergence of an EM Sequence of Iterates.
3.6 Examples of Nontypical Behavior of an EM (GEM) Sequence.
3.7 Score Statistic.
3.8 Missing Information.
3.9 Rate of Convergence of the EM Algorithm.
4. Standard Errors and Speeding up Convergence.
4.1 Introduction.
4.2 Observed Information Matrix.
4.3 Approximations to Observed Information Matrix: i.i.d. Case.
4.4 Observed Information Matrix for Grouped Data.
4.5 Supplemented EM Algorithm.
4.6 Bookstrap Approach to Standard Error Approximation.
4.7 Baker’s, Louis’, and Oakes’ Methods for Standard Error Computation.
4.8 Acceleration of the EM Algorithm via Aitken’s Method.
4.9 An Aitken Acceleration-Based Stopping Criterion.
4.10 conjugate Gradient Acceleration of EM Algorithm.
4.11 Hybrid Methods for Finding the MLE.
4.12 A GEM Algorithm Based on One Newton-Raphson Algorithm.
4.14 A Quasi-Newton Acceleration of the EM Algorithm.
4.15 Ikeda Acceleration.
5. Extension of the EM Algorithm.
5.1 Introduction.
5.2 ECM Algorithm.
5.3 Multicycle ECM Algorithm.
5.4 Example 5.2: Normal Mixtures with Equal Correlations.
5.5 Example 5.3: Mixture Models for Survival Data.
5.6 Example 5.4: Contingency Tables with Incomplete Data.
5.7 ECME Algorithm.
5.8 Example 5.5: MLE of t-Distribution with the Unknown D.F.
5.9 Example 5.6: Variance Components.
5.10 Linear Mixed Models.
5.11 Example 5.8: Factor Analysis.
5.12 Efficient Data Augmentation.
5.13 Alternating ECM Algorithm.
5.14 Example 5.9: Mixtures of Factor Analyzers.
5.15 Parameter-Expanded EM (PX-EM) Algorithm.
5.16 EMS Algorithm.
5.17 One-Step-Late Algorithm.
5.18 Variance Estimation for Penalized EM and OSL Algorithms.
5.19 Incremental EM.
5.20 Linear Inverse problems.
6. Monte Carlo Versions of the EM Algorithm.
6.1 Introduction.
6.2 Monte Carlo Techniques.
6.3 Monte Carlo EM.
6.4 Data Augmentation.
6.5 Bayesian EM.
6.6 I.I.D. Monte Carlo Algorithm.
6.7 Markov Chain Monte Carlo Algorithms.
6.8 Gibbs Sampling.
6.9 Examples of MCMC Algorithms.
6.10 Relationship of EM to Gibbs Sampling.
6.11 Data Augmentation and Gibbs Sampling.
6.12 Empirical Bayes and EM.
6.13 Multiple Imputation.
6.14 Missing-Data Mechanism, Ignorability, and EM Algorithm.
7. Some Generalization of the EM Algorithm.
7.1 Introduction.
7.2 Estimating Equations and Estimating Functions.
7.3 Quasi-Score and the Projection-Solution Algorithm.
7.4 Expectation-Solution (ES) Algorithm.
7.5 Other Generalization.
7.6 Variational Bayesian EM Algorithm.
7.7 MM Algorithm.
7.8 Lower Bound Maximization.
7.9 Interval EM Algorithm.
7.10 Competing Methods and Some Comparisons with EM.
7.11 The Delta Algorithm.
7.12 Image Space Reconstruction Algorithm.
8. Further Applications of the EM Algorithm.
8.1 Introduction.
8.2 Hidden Markov Models.
8.3 AIDS Epidemiology.
8.4 Neural Networks.
8.5 Data Mining.
8.6 Bioinformatics.
References.
Author Index.
Subject Index.
Tags: | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9149127006530762, "perplexity": 27921.78615388384}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386163952819/warc/CC-MAIN-20131204133232-00013-ip-10-33-133-15.ec2.internal.warc.gz"} |
http://mail-archives.apache.org/mod_mbox/maven-users/201003.mbox/%3C54b1e8691003040610s13cb0e37n788e1b84e4993929@mail.gmail.com%3E | # maven-users mailing list archives
##### Site index · List index
Message view
Top
From Brendan Sibre <bts...@gmail.com>
Date Thu, 04 Mar 2010 14:10:58 GMT
```We see that message when we have a jar in the repository that doesn't
actually have a POM file.
It realizes the JAR is in your local repository, so it doesn't try to
But it always tries to download the POM to find out if the artifact has any
dependencies (and POMs don't
have classifiers) but it's trying to find out if it has any dependencies.
It does that on every build.
However, my output always shows an INFO message "Unable to find resource
'groupX:artifactY:pom:versionZ'"
for each one as well.
Might be interesting if Maven provided a way to indicate in your dependency
declaration that you just
want the JAR w/o looking at the POM.
On Thu, Mar 4, 2010 at 4:52 AM, Thunder Farmer <thunder.farmer@gmail.com>wrote:
> Thanks for all of your responses.
>
> I tried with version 2.2.1.
> Still the same issue.
> Is it my luck? find a bug for Maven,:)~
>
> D:\temp\my-app>mvn -version
> Apache Maven 2.2.1 (r801777; 2009-08-07 03:16:01+0800)
> Java version: 1.6.0_10-rc
>
> Thanks,
> Thunder
>
> On Thu, Mar 4, 2010 at 3:22 PM, Anders Hammar <anders@hammar.net> wrote:
>
> > Did you try any of the latest recommended versions of Maven, like 2.2.1?
> > Maven 2.1.0 is generally a version to stay away from as it has issues...
> >
> > /Anders
> >
> > On Thu, Mar 4, 2010 at 07:03, Thunder Farmer <thunder.farmer@gmail.com
> > >wrote:
> >
> > > Hi,
> > >
> > > Thanks for your quick response.
> > > I can reproduce the issue by creating a simple project and adding a
> > > dependency with classifier to it.
> > > I create the project by "mvn archetype:create" command.
> > > In the pom, I add a dependency:
> > >
> > > <dependency>
> > > <groupId>com.informix</groupId>
> > > <artifactId>ifxjdbc</artifactId> <version>3.50</version>
> > > <classifier>JC3</classifier>
> > > <scope>compile</scope>
> > > </dependency>
> > > The informix JDBC jar and it's pom file are already in our local repo,
> > and
> > > I have local repo in my setting.xml
> > >
> > > Every time when I run "mvn compile", I get below output in the console
> > > [INFO] [resources:resources]
> > > [INFO] Using default encoding to copy filtered resources.
> > >
> http://repo1.maven.org/maven2/com/informix/ifxjdbc/3.50/ifxjdbc-3.50.pom
> > > [INFO] [compiler:compile]
> > >
> > > Though it doesn't really download the jar file, it consume significant
> > time
> > > to connect remote repo for a large project.
> > >
> > > Is it expected behavior of Maven?
> > >
> > > The project is attached.
> > >
> > > Thanks,
> > > Thunder
> > >
> > >
> > >
> > > On Thu, Mar 4, 2010 at 10:51 AM, Wendy Smoak <wsmoak@gmail.com> wrote:
> > >
> > >> On Wed, Mar 3, 2010 at 9:44 PM, Thunder Farmer <
> > thunder.farmer@gmail.com>
> > >> wrote:
> > >> > My problems is that seems Maven always download dependencies with
> > >> classifier
> > >> > even I specify the version.
> > >> > Is it the expected behavior or some thing goes wrong?
> > >> >
> > >> > Maven version: 2.1.0-M1
> > >> > Java version: 1.5.0_06
> > >>
> > >> This is the right place, but we need more information. Can you post a
> > >> snippet of the build output or error message that you're seeing, and
> > >> maybe the relevant portion of your pom.xml file (the problematic
> > >> <dependency>)?
> > >>
> > >> You might also try the build with the latest recommended stable Maven
> > >> still a problem.
> > >>
> > >> --
> > >> Wendy
> > >>
> > >> ---------------------------------------------------------------------
> > >> To unsubscribe, e-mail: users-unsubscribe@maven.apache.org
> > >> For additional commands, e-mail: users-help@maven.apache.org
> > >>
> > >>
> > >
> > >
> > > --
> > > Listen to Your Heart
> > >
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: users-unsubscribe@maven.apache.org
> > > For additional commands, e-mail: users-help@maven.apache.org
> > >
> >
>
>
>
> -- | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9319745302200317, "perplexity": 16222.32689645421}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-17/segments/1524125948617.86/warc/CC-MAIN-20180426222608-20180427002608-00044.warc.gz"} |
https://socratic.org/questions/how-do-you-simplify-n-5-using-only-positive-exponents | Algebra
Topics
How do you simplify n^-5 using only positive exponents?
Mar 6, 2018
$\frac{1}{n} ^ 5$ from the exponents rule
Explanation:
When learning your indices/ powers, one of the first rules you learn is
${\left(a\right)}^{-} n$= $\frac{1}{a} ^ n$
let's say i asked you to divide $\frac{{4}^{0}}{{4}^{3}}$, essentially would be intuitive to do is to subtract the powers, ${4}^{0 - 3} = {4}^{-} 3$ ,
so ${4}^{0} = 1$
therefore ${4}^{0 - 3} = \frac{1}{4} ^ 3 = {4}^{-} 3$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 7, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8034251928329468, "perplexity": 2731.9367612075152}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320304572.73/warc/CC-MAIN-20220124155118-20220124185118-00717.warc.gz"} |
https://brilliant.org/problems/convert-binary-to-decimal/ | # Convert binary to decimal
Calculus Level 5
Given a real number $$x\in[0; 1)$$ with binary expansion $$x=(0.a_1a_2a_3\ldots)_2$$, let $$f(x)=(0.a_1a_2a_3\ldots)_{10}$$ be the number obtained when interpreting the binary expansion of $$x$$ as a decimal expansion.
For example, $$f\left(\dfrac{1}{2}\right)=f((0.100\ldots)_2)=(0.100\ldots)_{10}=\dfrac{1}{10}$$.
Given that: $$\displaystyle I=\int\limits_0^1 f(x)dx=\dfrac{m}{n}$$, where $$m,n$$ are coprime positive integers.
Find the value of $$m+n$$.
× | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9600624442100525, "perplexity": 409.0648764089111}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549426629.63/warc/CC-MAIN-20170726202050-20170726222050-00695.warc.gz"} |
http://www.impan.pl/cgi-bin/dict?deduce | ## deduce
The case when $f$ is decreasing can be proved similarly, or else can be deduced from ...... | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.551222026348114, "perplexity": 940.9838327824684}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-50/segments/1480698544140.93/warc/CC-MAIN-20161202170904-00215-ip-10-31-129-80.ec2.internal.warc.gz"} |
https://gitbook.candao.io/whitepaper/cdo-based-voting-power | CDO - based voting power
Each CDO staker and liquidity provider will be automatically entitled to participate in Candao governance. The voting power of each entitled community member is calculated based on their CDO staking score.
$voting points = staking score rewards multiplier$
The above equation is subjected to reward multipliers unlocked as the staking score gets higher. For example, community members with accounts at level 7 will have x3 times as much voting power derived from their staking scores (for example, a Candao member with a 150 000 staking score will get 450 000 voting points).The above equation is subjected to reward multipliers unlocked as the staking score gets higher. For example, community members with accounts at level 7 will have x3 times as much voting power derived from their staking scores (for example, a Candao member with a 150 000 staking score will get 450 000 voting points).
Voting points are calculated per vote. They are not a separate token but the "weight" of a user vote.
Example: John has 450 voting power, Alex has 1500 voting power, and Tony has 1000 voting power.John and Tony voted to reject the submitted proposal, but Alex voted in favour. The issue has been accepted as the final voting count is 1500 in favor versus 1450 against. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 1, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.17151713371276855, "perplexity": 4939.60520861319}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656103331729.20/warc/CC-MAIN-20220627103810-20220627133810-00036.warc.gz"} |
http://mathinsight.org/minimization_maximization_problem_solutions | # Math Insight
### Solutions to minimization and maximization problems
#### Problem 1
1. To find the critical points, we look for points where $f'(x)$ is zero or not defined. \begin{align*} f'(x) &= 2xe^x+x^2e^x\\ &= (2x+x^2)e^x \end{align*} The derivative is always defined and is zero if \begin{align*} (2x+x^2)e^x &=0\\ 2x+x^2 &=0\\ x(2+x) &=0\\ x = 0 & \quad \text{or} \quad x=-2. \end{align*} Therefore, the critical points are $x=0$ and $x=-2$.
2. $f'(x) \gt 0$ if $x\ lt -2$ or $x \gt 0$, so $f$ is increasing when $x$ is in those intervals. $f'(x)\lt 0$ if $-2 \lt x \lt 0$, so $f$ is decreasing when $x$ is in that interval.
3. $x=-2$ is a local maximum since $f$ is increasing just below it and decreasing just above it. $x=0$ is a local minimum since $f$ is decreasing just below it and increasing just above it. Alternatively, we could have calculated the second derivative \begin{align*} f''(x) &= (2+2x)e^x+(2x+x^2)e^x\\ &= (2+4x+x^2)e^x. \end{align*} Since $f''(-2) = (2-8+4)e^{-2} = -2e^{-2} \lt 0$, we can conclude that $x=-2$ is a local maximum. Since $f''(0) = 2e^{0}=2 \gt 0$, we can conclude that $x=0$ is a local minimum.
4. To find the global maximum and minimum, we check the critical points and the endpoints: $f(-3) = 9e^{-3} \approx 0.45$, $f(-2) = 4e^{-2} \approx 0.54$, $f(0)=0$, $f(1)=e^1 \approx 2.72$. Therefore, the global minimum occurs at $x=0$ and the global maximum occurs at $x=1$.
#### Problem 2
1. To find the critical points, we look for points where $g'(y)$ is zero or not defined. \begin{align*} g'(y) &= (1-3y^2)e^{y-y^3} \end{align*} The derivative is always defined and is zero if \begin{align*} (1-3y^2)e^{y-y^3} &=0\\ 1-3y^2 &=0\\ y^2&=\frac{1}{3}\\ y &=\pm \frac{1}{\sqrt{3}} \end{align*} Therefore, the critical points are $y=\pm 1/\sqrt{3}$.
2. $g'(y) \gt 0$ if $-1/\sqrt{3} \lt y \lt 1/\sqrt{3}$, so $g$ is increasing when $y$ is in that interval. $g'(y) \lt 0$ if $y \lt -1/\sqrt{3}$ or $y \gt 1/\sqrt{3}$, so $g$ is decreasing when $y$ is in those intervals.
3. $y=-1/\sqrt{3}$ is a local minimum since $g$ is decreasing just below it and increasing just above it. $y=1/\sqrt{3}$ is a local maximum since $g$ is increasing just below it and decreasing just above it. Alternatively, we could have calculated the second derivative \begin{align*} g''(y) &= -6ye^{y-y^3}+(1-3y^2)^2e^{y-y^3}\\ &= [(1-3y^2)^2-6y]e^{y-y^3}. \end{align*} Since $g''(-1/\sqrt{3}) \approx 2.36 \gt 0$, we can conclude that $y=-1/\sqrt{3}$ is a local minimum. Since $g''(1/\sqrt{3}) \approx -5.09 \lt 0$, we can conclude that $y=1/\sqrt{3}$ is a local maximum.
4. To find the global maximum and minimum, we check the critical points and the endpoints: $g(-1) = e^{-1-(-1)^3} = e^0=1$, $g(-1/\sqrt{3}) \approx 0.68$, $g(-1/\sqrt{3}) \approx 1.47$, and $g(2) = e^{2-2^3} = e^{-6} \approx 0.0025$. Therefore, the global maximum occurs at $y=1/\sqrt{3}$ and the global minimum occurs at $y=2$.
#### Problem 3
1. $h'(z)=2(z-a)$, which is defined everywhere, so the only critical point is where $h'(z)=0$, which is $z=a$.
2. $h'(z) \lt 0$ for $z \lt a$, so $h$ is decreasing for $z \lt a$. $h'(z) \gt 0$ for $z \gt a$, so $h$ is increasing for $z \gt a$.
3. $h''(z)=2 \gt 0$, so $z=a$ is a local minimum. There is no local maximum.
4. We check the endpoints and the critical points. $h(0) = a^2$, $h(a) = 0$, and $h(3a) = 4a^2$. The global minimum occurs at $z=a$ and the global maximum occurs at $z=3a$.
#### Problem 4
1. Since \begin{align*} k'(q) &= \frac{2q}{b^2}e^{-q}-\frac{q^2}{b^2}e^{-q}\\ &= \frac{1}{b^2}(2q-q^2)e^{-q}, \end{align*} the derivative is defined everywhere and the only critical points occur where the derivative is zero: \begin{align*} \frac{1}{b^2}(2q-q^2)e^{-q} &= 0\\ 2q-q^2&=0\\ q(2-q) &=0\\ q = 0 & \quad \text{or} \quad q=2. \end{align*} The critical points are $q=0$ and $q=2$.
2. $k'(q) \lt 0$ for $q \lt 0$ and $q \gt 2$, so $k$ is decreasing in those intervals. $k'(q) \gt 0$ for $0 \lt q \lt 2$, so $k$ is increasing in those intervals.
3. $q=2$ is a local maximum since $k$ is increasing just below it and decreasing just above it. $q=0$ is a local minimum since $q$ is decreasing just below it and increasing just above it. Alternatively, we could have calculated the second derivative \begin{align*} k''(1) &= \frac{1}{b^2}(2-2q)e^{-q}-\frac{1}{b^2}(2q-q^2)e^{-q}\\ &= \frac{1}{b^2}(2-4q+q^2)e^{-q}. \end{align*} Since $k''(2) = (2-8+4)e^{-2} = -2e^{-2} \lt 0$, we can conclude that $q=2$ is a local maximum. Since $k''(0) = 2e^{0}=2 \gt 0$, we can conclude that $q=0$ is a local minimum.
4. To find the global maximum and minimum, we check the critical points and the endpoints: $k(0) = 0$, $k(2) = \frac{4}{b^2}e^{-2} \approx 0.54/b^2$, $k(4)=\frac{16}{b^2}e^{-4} \approx 0.29/b^2$. Therefore, the global minimum occurs at $q=0$ and the global maximum occurs at $q=2$.
#### Problem 5
1. The derivative \begin{align*} m'(x) &= (x-c) +x\\ &= 2x-c \end{align*} is defined everywhere, so the only critical point is $x=c/2$, the point where $m'(x)=0$.
2. $m'(x) \lt 0$ for $x \lt c/2$, so $m$ is decreasing for $x \lt c/2$. $m'(x) \gt 0$ for $x \gt c/2$, so $m$ is increasing for $x \gt c/2$.
3. $m''(x)=2 \gt 0$ so $x=c/2$ is a local minimum. There is no local maximum.
4. We check the endpoints and the critical points. $m(0) = 0$, $m(c/2) = (c/2)(-c/2) = -c^2/4$, and $m(3c) = 3c(2c) = 6c^2$. The global minimum occurs at $x=c/2$, and the global maximum occurs at $x=3c$.
#### Problem 6
1. The derivative \begin{align*} n'(x) &= (x+c) +x\\ &= 2x+c \end{align*} is defined everywhere, so the only critical point is $x=-c/2$, the point where $n'(x)=0$.
2. $n'(x) \lt 0$ for $x \lt -c/2$, so $n$ is decreasing for $x \lt -c/2$. $n'(x) \gt 0$ for $x \gt -c/2$, so $n$ is increasing for $x \gt -c/2$.
3. $n''(x)=2 \gt 0$ so $x=-c/2$ is a local minimum. There is no local maximum.
4. We check the endpoints and the critical points. $n(-3c) = (-3c)(-2c) = 6c^2$, $n(-c/2) = (-c/2)(c/2) = -c^2/4$, and $n(0) = 0$. The global minimum occurs at $x=-c/2$, and the global maximum occurs at $x=-3c$.
#### Problem 7
1. The pollution level rising corresponds to $p'(t) \gt 0$. The derivative is \begin{align*} p'(t) &= 8(3)t^2e^{-2t} -8(2)t^3e^{-2t}\\ &= 8(3t^2-2t^3)e^{-2t}. \end{align*} The critical points are where $3t^2-2t^3 = t^2(3-2t)=0$. This occurs when $t=0$ and when $t=3/2$. We don't care about negative $t$ for this problem. The derivative is positive for $0 \lt t \lt 3/2$ and is negative for $t \gt 3/2$. Therefore the pollution level continues to rise for one and one-half weeks after the spill.
2. Since the pollution rises before $t=3/2$ and decreases afterward, the maximum pollution level is reached at $t=3/2$, or one ane one-half weeks after the spill. The maximum pollution level is $p(3/2) = 8(3/2)^3e^{-2(3/2)} = 27e^{-3} \approx 1.34$.
#### Problem 8
Let $g(k)=k \cdot p(k) = 1000k (1-k)^2$ be the fish harvest if $k$ is the fraction of fish harvested. Since $k$ is the fraction of fish, the relevant range of $k$ is $0 \lt k \lt 1$. To find the maximum of $g$ for $0 \lt k \lt 1$, we look for critical points of $g$. To make the derivative easier to compute, we'll multiply out the function and write it as \begin{align*} g(k) &= 1000k (1-2k +k^2)\\ &= 1000 (k -2k^2+k^3). \end{align*} Then, the derivative is simply \begin{align*} g'(k) &= 1000 (1- 4k +3k^2). \end{align*}
To find the critical points where $g'(k)=0$, we need to solve $1-4k+3k^2=0$. We can factor this as $(1-k)(1-3k)=0$, so the critical points are $k=1$ and $k=1/3$. Or, if you couldn't remember your factoring, you could use the quadratic equation to solve \begin{align*} k &= \frac{4 \pm \sqrt{16-12}}{6}\\ &= \frac{4 \pm \sqrt{4}}{6}\\ &= \frac{4 \pm 2}{6}\\ &= 1 \quad \text{or} \quad 1/3 \end{align*}
To find the global maximum, we check the endpoints and the critical points. $g(0)=0$, $g(1)=0$, and \begin{align*} g(1/3) &= 1000(1/3)(2/3)^2\\ &= 4000/27\\ & \approx 148. \end{align*} The maximum occurs at $k=1/3$. One-third of the fish should be harvested each year ot maximize the first harvest. The average number of fish in the lake is $p(1/3)=1000(2/3)^2 \approx 444$. The number of fish harvested is $g(1/3) \approx 148$.
#### Problem 9
Let $g(k)=k \cdot p(k) = ck (1-k)^2$ be the fish harvest if $k$ is the fraction of fish harvested. Since $k$ is the fraction of fish, the relevant range of $k$ is $0 \lt k \lt 1$. To find the maximum of $g$ for $0 \lt k \lt 1$, we look for critical points of $g$. To make the derivative easier to compute, we'll multiply out the function and write it as \begin{align*} g(k) &= c k (1-2k +k^2)\\ &= c (k -2k^2+k^3). \end{align*} Then, the derivative is simply \begin{align*} g'(k) &= c (1- 4k +3k^2). \end{align*}
To find the critical points where $g'(k)=0$, we need to solve $1-4k+3k^2=0$, just as in the previous problem. From above, the critical points are $k=1$ and $k=1/3$.
To find the global maximum, we check the endpoints and the critical points. $g(0)=0$, $g(1)=0$, and \begin{align*} g(1/3) &= c(1/3)(2/3)^2\\ &= 4c/27 \end{align*} The maximum occurs at $k=1/3$. One-third of the fish should be harvested each year ot maximize the first harvest. The average number of fish in the lake is $p(1/3)=4c/9$. The number of fish harvested is $g(1/3) = 4c/27$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9998763799667358, "perplexity": 275.52020868441065}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-39/segments/1505818689845.76/warc/CC-MAIN-20170924025415-20170924045415-00590.warc.gz"} |
https://www.allaboutcircuits.com/textbook/direct-current/chpt-10/maximum-power-transfer-theorem | # Maximum Power Transfer Theorem
## Chapter 10 - DC Network Analysis
The Maximum Power Transfer Theorem is not so much a means of analysis as it is an aid to system design. Simply stated, the maximum amount of power will be dissipated by a load resistance when that load resistance is equal to the Thevenin/Norton resistance of the network supplying the power. If the load resistance is lower or higher than the Thevenin/Norton resistance of the source network, its dissipated power will be less than the maximum.
This is essentially what is aimed for in radio transmitter design, where the antenna or transmission line “impedance” is matched to final power amplifier “impedance” for maximum radio frequency power output. Impedance, the overall opposition to AC and DC current, is very similar to resistance and must be equal between source and load for the greatest amount of power to be transferred to the load. A load impedance that is too high will result in low power output. A load impedance that is too low will not only result in low power output but possibly overheating of the amplifier due to the power dissipated in its internal (Thevenin or Norton) impedance.
### Maximum Power Transfer Example
Taking our Thevenin equivalent example circuit, the Maximum Power Transfer Theorem tells us that the load resistance resulting in greatest power dissipation is equal in value to the Thevenin resistance (in this case, 0.8 Ω):
With this value of load resistance, the dissipated power will be 39.2 watts:
If we were to try a lower value for the load resistance (0.5 Ω instead of 0.8 Ω, for example), our power dissipated by the load resistance would decrease:
Power dissipation increased for both the Thevenin resistance and the total circuit, but it decreased for the load resistor. Likewise, if we increase the load resistance (1.1 Ω instead of 0.8 Ω, for example), power dissipation will also be less than it was at 0.8 Ω exactly:
If you were designing a circuit for maximum power dissipation at the load resistance, this theorem would be very useful. Having reduced a network down to a Thevenin voltage and resistance (or Norton current and resistance), you simply set the load resistance equal to that Thevenin or Norton equivalent (or vice versa) to ensure maximum power dissipation at the load. Practical applications of this might include radio transmitter final amplifier stage design (seeking to maximize the power delivered to the antenna or transmission line), a grid-tied inverter loading a solar array, or electric vehicle design (seeking to maximize the power delivered to drive motor).
### Maximum Power Doesn’t Mean Maximum Efficiency
The Maximum Power Transfer Theorem does not: Maximum power transfer does not coincide with maximum efficiency. Application of The Maximum Power Transfer theorem to AC power distribution will not result in maximum or even high efficiency. The goal of high efficiency is more important for AC power distribution, which dictates a relatively low generator impedance compared to the load impedance.
Similar to AC power distribution, high fidelity audio amplifiers are designed for a relatively low output impedance and a relatively high speaker load impedance. As a ratio, “output impedance”: “load impedance” is known as damping factor, typically in the range of 100 to 1000.
Maximum power transfer does not coincide with the goal of the lowest noise. For example, the low-level radio frequency amplifier between the antenna and a radio receiver is often designed for the lowest possible noise. This often requires a mismatch of the amplifier input impedance to the antenna as compared with that dictated by the maximum power transfer theorem.
REVIEW:
• The Maximum Power Transfer Theorem states that the maximum amount of power will be dissipated by a load resistance if it is equal to the Thevenin or Norton resistance of the network supplying power.
• The Maximum Power Transfer Theorem does not satisfy the goal of maximum efficiency.
RELATED WORKSHEET:
• Share
Published under the terms and conditions of the Design Science License | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8039206862449646, "perplexity": 731.3381398986746}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-45/segments/1603107867463.6/warc/CC-MAIN-20201019232613-20201020022613-00427.warc.gz"} |
http://www.smashcompany.com/ | ## LATEST ENTRIES
September 30th, 2016
# After 1970, people had to spend more on rent
Interesting:
From 1940 to 1960 across 20 large U.S. cities, rental housing’s price fell, renters’ incomes rose, rent’s share in household budgets fell, and, as expected, renters’ real housing consumption increased. From 1970 to 2010, rental housing’s price increased, renters’ incomes decreased, but, unexpectedly, renters’ real housing consumption increased. We find neither demographics nor housing supply factors account for the anomalous post-1970 increase in renters’ housing consumption. We conclude that after 1970 there was a nationwide increase in renters’ preferences for ...
September 30th, 2016
# The rarity of a game that allows much expression of femslash
Overwatch fans and femslash
Slash, as this is known in fandom circles, has a long history of sparking the imagination, stretching as far back as Star Trek. Historically, a lot of slash has focused on men’s relationships with each other (M/M), while fan-created material about women’s relationships (also known as femslash, or F/F) feels an underappreciated but no less ferocious wing of shipping. An informal 2013 count of the tags in on Archive of Our Own, a popular fanfiction library, shows ...
September 30th, 2016
# An unusual election in the USA
This isn’t normal. This will be a reference point for decades to come. The Republican nominee has a strange obsession denouncing a woman who disappointed him 30 years ago. And as one commenter said, the use of “my” in “my worst Miss Universe” is absolutely creepy. He doesn’t own her.
Source
September 29th, 2016
# Online beauty gurus have become much more reliable than brands
Interesting:
This seems to mirror general consumer consensus that online beauty gurus have become much more reliable than brands. The brands are, in turn, increasingly reliant on bloggers for marketing. … The beef stems from a Vogue roundtable published on Sunday in which several editors discussed Milan Fashion Week and denigrated style bloggers in the process. Vogue.com’s chief critic Sarah Mower turned a nose up, stating, “The professional blogger bit, with the added aggression of the street photographer swarm who attend them, is ...
September 27th, 2016
# Why wouldn’t people buy Hermione Granger and the Philosopher’s Stone?
This is an interesting argument, that Hermione might have been one of the more original aspects of Harry Potter, and perhaps its most tolerable aspect.
This is something that the Harry Potter fan community has been discussing for years: Hermione drives the story because she has her own story. No one in their right mind would trust 13-year-old Harry Potter with a Time Turner, but Hermione gets one and she deserves it. She dates a celebrity, and she outsmarts Rita Skeeter, ...
September 27th, 2016
# Andrew Montalenti: Ask a teacher, police officer, or firefighter if they are paid proportional to the value they add
It’s an interesting essay, but I can’t go along with the complacency that’s implied. If people are paid unfairly, then we should try address that. Programming might seem to be reasonably paid when compared to doctors or lawyers or teachers, but there is the larger issue, are workers, as a group, being paid fairly? Anyone who reads history is aware that during the Gilded Age monopolists bribed politicians to enrich themselves to the detriment of the public. The ...
September 27th, 2016
# Inequality ruins romance
Interesting article:
Lily is, essentially, upper middle class. She has enough money and status to play bridge and attend balls with the truly wealthy, but she is living beyond her means, and her debts are always mounting. In order to secure a place for herself in society and to pay off her debts, she has to find a rich husband. Lily’s story illustrates the strain of the upper middle class trying to achieve true wealth—and the terrible consequences of failure—in a ...
September 20th, 2016
# Software as a metaphor for human behavior
I’m focusing on “sensitivity chip”. Interesting:
Jennifer Aniston is interviewed by Vanity Fair’s Leslie Bennetts. In the profile, titled The “Unsinkable Jennifer Aniston,” Aniston (crying the whole time) speaks on her marriage to Pitt, telling Bennetts, “We’re divorced, and you can see why,” referring to the aforementioned W spread.
She adds, “Brad is not mean-spirited; he would never intentionally try to rub something in my face. In hindsight, I can see him going, ‘Oh—I can see that that was inconsiderate.’ But I ...
September 18th, 2016
# Rapidly Exploring Random Trees
Interesting. It says the RRT proceeds by breaking the Voronoi spaces into smaller Voronoi spaces. The algorithm has a bias towards unexplored territory, unlike a purely random algorithm, which tends to loop back to explored space. I didn’t dig into the algorithm, but I can imagine how this would be useful in some situations.
Source
September 18th, 2016
# Women at the White House amplify what they each say, so as to avoid being ignored
This is brilliant:
In the early days of the Obama White House, nearly two-thirds of Obama’s senior staffers and advisors were men. The Washington Post reports that the “women complained of having to elbow their way into important meetings. And when they got in, their voices were sometimes ignored.”
So, the women of the Obama White House banded together and sketched out a strategy that would effectively force their male colleagues to listen to them. They called it “amplification,” a simple ...
September 18th, 2016
# As a consolidation client for Kinesis, ZeroMQ is much better than Kafka
This is fantastic:
With the problem of real-time log consolidation solved with ZeroMQ, supporting durable storage of logs for later post-processing becomes a smaller and a much more manageable challenge. For example, off the shelve solutions like Logstash are capable of capturing data from ZeroMQ and publishing it to a variety of destinations. In our particular situation at Auth0, we are already using AWS Kinesis, ElasticSearch, and Kibana as a log processing pipeline in other parts of our operations. As such we ...
September 18th, 2016
# I always learn what I need to know about a year too late
At Celolot I wrote a bunch of Clojure apps that talked to each other over Redis thanks to Carmine/Nippy. We passed around maps, and each app checked a field in the map to see if the map was a message that it was suppose to respond to.
But I bet this is a thousand times faster:
ZeroMQ does not have a first class notion of a topic, yet it does have a first class concept of a subscription filter. Subscription filters ...
September 18th, 2016
# Camille Fournier on ephemeral nodes in etcd
I missed this the first time. In etcd a service needs to constantly update the fact that it is alive. If it dies, its info disappears. So other services can contact etcd and ask “Who is alive right now?”
ZooKeeper allows stateful connections. Thick clients. But what happens when you try to use ZooKeeper from a language that does not allow threads? Do you block on the only thread that you have?
For pub-sub she recommends RabbitMQ or ZeroMQ.
Source
September 18th, 2016
# Why would I ever want to use Docker?
I’m trying to be open minded about Docker, but it is a struggle to grok why this is good. Do I want to bind all dependencies to my app? Great, then I’ll build uberjars that combine everything into 1 binary. But how will I work with Ruby On Rails? That’s easy: it is time to move away from Ruby On Rails. If Ruby can only be kept alive by using Docker, then we should give up on Ruby.
How will ...
September 18th, 2016
# The universe as a Church encoding
I think it is extremely messy that math has integers, fractions, irrational numbers and worse. If I was rich, I would work on a model of the universe where the only primitive is the function. One has to admit, the idea of a universe with only one primitive is extremely attractive.
In mathematics, Church encoding is a means of representing data and operators in the lambda calculus. The data and operators form a mathematical structure which is embedded in the ...
September 18th, 2016
# Unary Numeral System
Interesting:
Addition and subtraction are particularly simple in the unary system, as they involve little more than string concatenation. The Hamming weight or population count operation that counts the number of nonzero bits in a sequence of binary values may also be interpreted as a conversion from unary to binary numbers. However, multiplication is more cumbersome and has often been used as a test case for the design of Turing machines.
Compared to standard positional numeral systems, the unary system is inconvenient ...
September 18th, 2016
# What sort of apps would we get if everyone could program?
This issue has been brought up many times over the decades, most especially with Hypercard, and then again with the invention of the Web in 1989. Are there categories of software that we don’t get now because the only people who create software are highly skilled specialists?
Here is a story of a young woman creating an app, and it suggests what the world might be like if anyone could create software:
A lot has changed since I was in ...
September 18th, 2016
# Video games as a supplement to other mental medications
Interesting:
At a young age I knew I was different, but always just hid behind a theatre kid exterior and chalked all my anxiety up to “budding creativity” that just needed an outlet. Surprise! Turns out my anxiety is actually a chemical imbalance in my brain that kept escalating until it exploded. I was nearly 21, living at college, and having a full-on anxiety attack every day. After dropping about 10 pounds (I’m very small to begin with) and not being ...
September 18th, 2016
# The promise of equity no longer aligns the interests of workers and startup founders
This essay is fantastic:
Sure enough, companies like Snapchat and Palantir have adopted policies that either vest employee options over a longer period of time (five years in the case of Palantir) or back-weight the bulk of vesting later in an employee’s tenure (Snapchat vests only 10% the first year, 20% in the second, 30% in the third, and 40% in the fourth). Still, while this adjustment may strike VCs and founders as a reasonable tradeoff, lengthening the time workers are ...
September 18th, 2016
# It took me 10 years to write that 5 line app
There is the story where Picasso paints a quick sketch and wants a huge amount of money for it, and the art collector says “It only took you 15 minutes to make that sketch!” and Picasso says “I spent 60 years learning how to do that in 15 minutes.”
Maybe something like this applies when it comes to microservices. When I advocate for microservices, I bring 17 years of experience to the conversation. The first 7 of those years meant ...
September 18th, 2016
# The economy is a collection of many distinct but interconnected practices
Or as Joseph Schumacher said, “The social process is really one indivisible whole!”
This is interesting:
We should see our economy not simply as a capitalist market system but as a collection of “many distinct but interconnected practices”. Neither the traditional economist’s focus on firms in markets nor the Marxist political economist’s focus on exploitation of wage labour by capital is a viable way of understanding the real economy, and the book takes some steps towards an alternative view.
Both of ...
September 18th, 2016
# Post-Real Theory
I think this is actually happening in most fields, not just economics. It’s happening in physics, in biology, in computer technology:
In response to the observation that the shocks [in DSGE models] are imaginary, a standard defense invokes Milton Friedman’s (1953) methodological assertion from unnamed authority that “the more significant the theory, the more unrealistic the assumptions (p.14).” More recently, “all models are false” seems to have become the universal hand-wave for dismissing any fact that does not conform to the ...
September 18th, 2016
# Petty Revenge Stories
I am thinking of launching yet another blog service, so I am studying existing blog services.
I am curious how certain Tumblr blogs manage to attract enough of an audience that they get a steady stream of submissions. Petty Revenge Stories, for instance. How did this get famous enough that now it gets a steady supply of submissions.
As near as I can tell, the owner of Petty Revenge Stories never speaks. They do not offer a performance of their ...
September 18th, 2016
# Is this a story about women in journalism in the 1920s, or is this a story about burnout?
Since I’ve dealt with my own episodes of burnout, I would say this sounds a lot like burnout. If you both love a profession and find yourself unmotivated to do the work, then you are suffering from depression/burnout.
The couple married in 1934. Velva sold her automotive Corona and would soon retire to the serenity of the Outpost Estates home where Rick grew up. She was free from the rat race.
And yet, when I looked in city directories for the ...
September 18th, 2016
# For the last 10,000 years, the banking industry has relied on eventual consistency
Why do computer programmers feel smug offering the following example, when it is so clearly wrong?
Transactions, to a database, are important, because banks must keep track of money. Suppose a person were to move $100 from their Savings account to their Checking account. Suppose$100 is added to checking, and just then the electricity dies, and the computers die, before $100 can be subtracted from their Savings account. The person now has an extra$100, which they should not ...
September 17th, 2016
# How not to transition from celebrity life to politics
Ivanka Trump is used to getting easy questions from the celebrity press. She is surprised to face tough questions now that she has entered politics. Interesting:
For the rest of the interview, she’s combative: “You said he made those comments,” she says to Gupta. “I don’t know that he said those comments.” When Gupta reiterates that, yes, Donald Trump said pregnancy was an inconvenience, Trump responds, “There’s plenty of time for you to editorialize around this, but I think he put ...
September 17th, 2016
# I keep really good company
Edsger W. Dijkstra
Alan Kay
Paul Graham
Richard Mansfield
Eric Raymond
Jeff Atwood
Linus Torvalds
Oscar Nierstrasz
Rich Hickey
Eric Allman
Joe Armstrong
Rob Pike
John Barker
Lawrence Krubner (me)
Asaf Shelly
I must be doing something right to get cited alongside Edsger W. Dijkstra, Alan Kay, Paul Graham, Linus Torvalds, and Rich Hickey.
Source
September 17th, 2016
# Americans are less enamored of the status quo
Interesting:
Politics is seeping into American public life — and with it, the belief that the status quo isn’t worth saving
We’ve seen in this cycle — in the candidacy of Bernie Sanders as well as Donald Trump — the appeal of a politics that puts forward a robust alternative vision for society. A politics that doesn’t just promise improvements to the lives of individual voters but declares what America itself ought to be.
That’s not a vision that can be put into ...
September 17th, 2016
# Failing to expand cities will come at a cost
This article does not do much more than remind us that automobiles have been the primary transportation mechanism of the last 100 years, and therefore growth and autos are linked. A different technology would generate different results. But we should also the cultural and political paralysis that contributes to this. Ideas about private property work well when we discuss unsullied fresh ground way out in the middle of nowhere. Ideas of private property break down when we are discussing Manhattan. ...
September 17th, 2016
# I am confused why large firms acquire smaller firms
It is well known that most mergers are failures. Hundreds of good studies have been written on the subject. And yet large firms continue to acquire smaller firms.
There are other ways that large firms could behave:
1.) A large firm, with mature markets and steady cash flows, act as venture capitalists, funding hundreds of small firms and setting them free
2.) A large firm, with mature markets and steady cash flows, could simply give the money back to investors
So why acquire? ...
September 17th, 2016
# When is consistency needed in a database?
This is a great comment :
Consistently is overvalued. Requiring consistency in distributed system generally leads to designs that reduces availability. Which is one of the reasons that bank transactions generally do not rely on transactional updates against your bank. “Low level” operations as part of settlement may us transactions, but the bank system is “designed” (more like it has grown by accretion) to function almost entirely by settlement and reconciliation rather than holding onto any notion of consistency. The real world rarely involves ...
September 17th, 2016
This seems like an unnecessary self-inflicted wound. I get defending one’s work as an artists, but there is a conflict between asserting a vision as an artist and being a businessperson who has a comfortable relationship with one’s customers.
Source
September 16th, 2016
# For the USA economy, 2015 was the best year since at least 1999
Very interesting:
That is great news of course. Do note however the following (NYT):
The median household income is still 1.6 percent lower than in 2007, before the recession. It also remains 2.4 percent lower than the all-time peak reached during the economic boom of the late 1990s.
Even with this unexpected and quite remarkable income gain, America is close to having gone twenty years without a significant money pay hike for its middle class category.
And do note this: two days ago, ...
September 16th, 2016
# The fraud at WellsFargo is historic
So you might have bank accounts that you don’t want and you never asked for? You might be charged fees on these accounts? Reasonable people should find this terrifying:
If you Google the phrase “bank cross-selling,” you don’t get many hits about the recent Wells Fargo scandal, in which thousands of bank employees were fired for the most blatant sort of corporate fraud. “Team members,” as Wells Fargo prefers to call its employees, had strict mandates to sign existing customers ...
September 11th, 2016
# Why did Salesforce use markup tags for VisualForce?
By now, I think we can agree, using HTML for the web was a mistake. But Sir Tim Berners-Lee could not have known that back in 1989. He was thinking that he could create a Semantic Web, and for that, the use of a markup language was defensible. Only in retrospect do we see that HTML was mostly used as a GUI for TCP/IP. Eventually Sir Tim Berners-Lee conceded the point, and so he went off and created RDF.
But ...
September 11th, 2016
# Could crime prediction software force patterns of crime to continue as they have in the past?
If a town starts off, years ago, policing an area heavily because that area is black, and therefore many incidents in that area are formally reported, and then software is used to look for patterns of reports, and the software highlights the black areas, then we are using software to legitimate the over-policing of certain neighborhoods.
Very interesting article:
The fact that we even call these systems “predictive” is itself a telling sign of excessive confidence in the systems. The ...
September 11th, 2016
# Are ebooks in decline?
Interesting:
And self-published “indie” authors — in part because they get a much bigger cut of the revenue than authors working with conventional publishers do — are now making much more money from e-book sales, in aggregate, than authors at Big Five publishers.
…The AAP also reported, though, that e-book revenue was down 11.3 percent in 2015 and unit sales down 9.7 percent. That’s where things get misleading. Yes, the established publishing companies that belong to the AAP are selling fewer e-books. ...
September 11th, 2016
# Rolling coal is sheer aggression
This is an interesting point:
Entire dissertations could be written about rolling coal. Even more than Trump’s ascension, it seems to perfectly capture a moment in time, an inarticulate yawp of protest from angry white men. They feel disdained and overlooked and they will blow thick black smoke in your face until you pay attention.
There’s no faux nostalgia involved. Unlike with, say, hunting, there’s no tale of rugged rural self-sufficiency to draw on. This is not some sturdy heartland tradition ...
September 11th, 2016
# When co-workers doubt complaints of sexual harrassment
This is a story that I think will become a reference point, in future years, for how badly one’s co-workers react to this kind of thing:
Skepticism of women who report sexual misconduct is deeply ingrained in our culture. It’s a reflexive, often subconscious bias that can be hard to shake. Some people will take longer to shake it than others — even in the relatively hip-to-feminism era of 2016 America.
So it’s always encouraging to see people realize and publicly ...
September 11th, 2016
# Women generally do more housework than men, but this pattern varies immensely in degree across countries and over time
The most interesting sentence:
These patterns of behaviour exist even among individuals living alone
This is a great article, but it doesn’t mention the Sapir–Whorf hypothesis. But this seems to be an example of Sapir–Whorf:
Women generally do more housework than men, but this pattern varies immensely in degree across countries and over time. Why?
Using time-use survey data from the US, we show that female immigrants coming from countries whose dominant language relies on sex-based grammatical distinctions bear a far larger share of ...
September 8th, 2016
# Political reactions to recent protests in Dallas
Interesting the way some people see broad conspiracies in what is probably a small terrorist plot:
Walsh gained a reputation while in office for aligning himself with a group of politicians who showed themselves to be rape apologists just before the 2012 election (which Walsh lost to Rep. Tammy Duckworth). Walsh, who is pro-life without exception, also somehow misinterpreted science so grossly that he stated publicly that it was virtually impossible for a woman to die from a pregnancy.
“This is an ...
September 6th, 2016
# When women’s entrance to the workforce had the most effect
I am surprised that women’s entry into the labor force was no longer a driving power as early as the 1970s. The big surge is entirely in the 1960s.
Source
September 5th, 2016
# Comparing data sets that are imbalanced
Interesting:
Research on imbalanced classes often considers imbalanced to mean a minority class of 10% to 20%. In reality, datasets can get far more imbalanced than this. Here are some examples:
1.) About 2% of credit card accounts are defrauded per year1. (Most fraud detection domains are heavily imbalanced.)
2.) Medical screening for a condition is usually performed on a large population of people without the condition, to detect a small minority with it (e.g., HIV prevalence in the USA is ~0.4%).
3.) Disk ...
September 5th, 2016
# Base 10 numbers need log(10) digits to be described
I’m sure I knew this example once, but I’d completely forgotten it, and it is so perfectly obvious when we talk to non-technical people and they ask for an example of what logarithmic growth looks like:
In mathematics, logarithmic growth describes a phenomenon whose size or cost can be described as a logarithm function of some input. e.g. y = C log (x). Note that any logarithm base can be used, since one can be converted to another by multiplying ...
September 5th, 2016
# Accessing any single element in an array takes constant time as only one operation has to be performed to locate it.
This seems like it could be used as a trick question that would trip me up during a job interview:
An algorithm is said to be constant time (also written as O(1) time) if the value of T(n) is bounded by a value that does not depend on the size of the input. For example, accessing any single element in an array takes constant time as only one operation has to be performed to locate it. However, finding the minimal ...
September 5th, 2016
# Beware Big O Notation in higher level languages
This essay has a nice bit of details about a general point that needs to be made:
Here we get the result that will be counterintuitive to many. No matter how large n gets, the Array List still performs better overall. In order for performance to get worse, the ratio of inserts to iterations has to change, not just the length of the collection. Note that isn’t an actual failure of Big O analysis, it is merely a common human failure ...
September 5th, 2016
# The gamification of Slack makes it addictive but also makes it a drain
Very interesting:
Everything bad about Slack is fundamentally Slack’s fault. Slack’s sane default for a new user is to play a sound and send a desktop notification every time anything happens anywhere. There is no way to simply turn off the screaming red circle on the dock icon. There is no way to simply fold away the sidebar so you can focus on whatever it is you are trying to do. These UI nitpicks help us understand Slack’s conception of the ...
September 5th, 2016
# Some blunt advice on management
This is an interesting essay:
Managing people at startups is different because you have no safety net. You may think, having spent a few years at a big company in a management position, that you know how to manage already. You’ve given performance reviews, done interviews, dealt with project timelines, played politics. You know the basics. Right? Here’s what you don’t see until you leave the safety of a big company. You don’t see the millions of invisible systems all around you ...
September 5th, 2016
# Hausdorff space
What is fully normalized data? Reading up on this, it is fascinating to consider the overlap here between database schemas and topology:
In topology and related branches of mathematics, a Hausdorff space, separated space or T2 space is a topological space in which distinct points have disjoint neighbourhoods. Of the many separation axioms that can be imposed on a topological space, the “Hausdorff condition” (T2) is the most frequently used and discussed. It implies the uniqueness of limits of sequences, nets, ...
September 5th, 2016
# What Gawker did well
Interesting:
What Gawker did at its best was stand up and say, “No, you’re right, these are lies, you are correct to think that you are being lied to” and for however long that assertion hung there in the air you were able remind yourself that you weren’t wrong to feel discomfort with what whatever narrative they were pushing at you. You weren’t alone. It did not make the world better but at least it pressed pause on the world’s becoming ...
September 5th, 2016
# What is continuous?
I like this simple set of examples:
As an example, consider the function h(t), which describes the height of a growing flower at time t. This function is continuous. By contrast, if M(t) denotes the amount of money in a bank account at time t, then the function jumps at each point in time when money is deposited or withdrawn, so the function M(t) is discontinuous.
Source
September 5th, 2016
# The nostalgia for old games
Interesting that someone brought back Runequest:
Thanks to your overwhelming support during our Kickstarter, we are proud to announce that RuneQuest 2 (and 1) are Back in Print and back with Chaosium! Just in time to celebrate the 50th Anniversary of Glorantha.
This is the game that started it all. It defined the d100 role-playing experience, with skills instead of levels and having a game tied into a deep mythic background: Greg Stafford’s world of Glorantha. Steve Perrin and Ray Turney worked with ...
September 5th, 2016
# How Uber failed in Japan
Really interesting:
This strategy has been phenomenally successful in America, but has failed miserably in Japan for three key reasons. #1 People Trust Government More than Industry My libertarian friends in San Francisco find this baffling. They often dismiss it as brainwashing or propaganda when I explain it, but it’s not. The United States is unique in the free world for our visceral disgust for and distrust of our own government.
It’s not that people is Asia consider government motivations to be pure. Over ...
September 5th, 2016
# Content on the web doesn’t pay, and giving up on comments will make everything worse
It’s a failure of leadership when a content play can not figure out how to make money off of comments.
NPR is making an announcement today that is sure to upset a loyal core of its audience, those who comment online at NPR.org (including those who comment on this blog). As of Aug. 23, online comments, a feature of the site since 2008, will be disabled.
With the ...
September 5th, 2016
# Progressive values in science-fiction and fantasy
Interesting to see this change happening now and not in, say for instance, 1975.
The three fiction longer-fiction categories were each won by a woman of color: N.K. Jemisin (Best Nove), Nnedi Okorafor (Best Novella) and Hao Jingfang (Best Novellette). Additionally, Michi Trota, one of the editors of Uncanny Magazine, noted that she was the first Filipino to win a Hugo.
Jingfang, who hails from China, won for her story Folding Beijing, and is the second Chinese science fiction authors in ...
September 5th, 2016
# Mena Trott did not understand the online world she was helping to build
This has been common, with the technical and business leaders having no understanding of the implications of what they were building. This is the norm, not the exception.
Trott has an interesting golden rule that she would like to see bloggers adopt. “If you aren’t going to say something directly to someone’s face, than don’t use online as an opportunity to say it,” she says. “It is this sense of bravery that people get when they are anonymous that gives ...
September 5th, 2016
# It’s not even XML!
Dave Winer said he is deeply depressed. Sometimes he seems frightened by the march of change. I suppose that is an aspect of depression. His initial fear of JSON seems like an expression of fear:
I’ve been hearing, off in the distance, about something called JSON, that proposes to solve a problem that was neatly solved by XML-RPC in 1998, the encoding of arrays and structs in a format that could easily be processed by all programming languages. The advantage ...
September 5th, 2016
# Finding novelty via friends is a metric not yet captured by recommendation engines
This is a good point:
The traditional regime of recommendation systems has been obsessed with (1). What’s the uplift of recommendation algorithm A vs recommendation algorithm B? Which is driving more click-thrus and conversions?
There’s something fundamentally broken in the this way of thinking though. I don’t care what the computer says. I care about what my friends say. The meaningful music I’ve discovered over the last 10 years has been music liked by someone I respect. Friends. Other musicians I ...
September 5th, 2016
# Detecting voting rings with HyperLogLog
While this seems like a clever trick, I typically want a lot of metrics regarding voting, so throwing away the metadata doesn’t seem like an option to me. As an aggregate tool whose only purpose is finding voting rings, maybe this useful maybe?
But consider what would happen if we created a HyperLogLog counter for every user on Reddit, and any time that a user receives an upvote, we update the corresponding HyperLogLog counter with the id of the user ...
September 5th, 2016
# Manila Social Club
Source
September 5th, 2016
# Great browser software in 1996
These technologies sound so amazing, I wonder what happened to them?
Atlas is the precursor to the next step in Navigator’s evolution, Version 3.0. It’s “alpha” code; in other words, that celebrated tower in Pisa is more stable. When it works, Atlas promises to deliver:
VRML viewing. VRML (Virtual Reality Modeling Language) is one of the competing standards for expressing three-dimensional information in compact form. VRML documents can be static or interactive. For example, you could create a Web page that ...
September 5th, 2016
# Social media is the highlight reel of other people’s lives
Interesting comment:
Social media and the internet has made it incredibly easy to see the various people out there who are in the top of their league at any particular hobby, vocation or activity, and made it seem like that’s the ‘norm’. If you’re an entrepreneur, it can feel like everyone’s making millions off their startup ideas and that anyone who isn’t is a failure. If you’re a web developer, it can seem like the majority of developers are experts in every ...
September 5th, 2016
# The oxytocin receptor gene comes in several variants
Interesting:
“The oxytocin receptor gene comes in several variants, and there are indications that some of these variants make you respond in less reactive ways to oxytocin in your blood,” explains Luc Goosens, a developmental psychologist at the University of Leuven in Belgium. If you have the most common genotype of the oxytocin receptor gene, GG, you may be more attuned to the emotions of others but also more sensitive to rejection and more likely to end up feeling lonely.
In a ...
September 5th, 2016
# The Big O cheat sheet
I just discovered the Big O cheat sheet and I think this is very useful:
Source
September 5th, 2016
# Raj Bhakta is a pathetic loser
This fellow Bhakta sounds like a lot of the wealthy people I’ve had as clients and as business partners. Immune to normal reality because of their wealth. They “fail” by doing something embarrassing, but they are incapable of failing in the Greek Tragedy sense: of falling out of their social class. Their family won’t let them fall.
Actually, I don’t know anything about Bhakta, but he does remind me of my ex-business partner:
1.) parties too much
2.) wants a glamorous life
3.) believes ...
September 4th, 2016
# Faraday’s breakthrough came when he wrapped two insulated coils of wire around an iron ring
I just realized that I’ve been confusing Faraday and Maxwell. It’s Maxwell who did the 4 equations.
Faraday’s breakthrough came when he wrapped two insulated coils of wire around an iron ring, and found that upon passing a current through one coil a momentary current was induced in the other coil.[2] This phenomenon is now known as mutual induction.[44] The iron ring-coil apparatus is still on display at the Royal Institution. In subsequent experiments, he found that if ...
September 4th, 2016
# The 1990s were a golden age for paper magazines
Even if the big profits were for the weeklies (Time, Lucky, Life) back in the 1950s and 1960s, for originality and dare, the magazines in the 1990s were amazing.
August 3rd, 2016
# The IMF admits it has favored austerity at the wrong time and the wrong place
An interesting article:
It describes a “culture of complacency”, prone to “superficial and mechanistic” analysis, and traces a shocking breakdown in the governance of the IMF, leaving it unclear who is ultimately in charge of this extremely powerful organisation.
The report by the IMF’s Independent Evaluation Office (IEO) goes above the head of the managing director, Christine Lagarde. It answers solely to the board of executive directors, and those from Asia and Latin America are clearly incensed at the way European ...
August 3rd, 2016
# The importance of the blogosphere for economics
An interesting article:
A few weeks ago was typical. After some time off, my feed aggregator displayed 794 blog posts, 56 of them foolishly filed into the “must read” folder. Here lay a polemic blasting the FT for worrying about China’s debts; there a graph strewn post about US inflation expectations. Virtuoso “infovore” Tyler Cowen had dug up a fascinating passage on how China runs monetary policy. Another polymath, Brad DeLong (former Clinton staffer and tireless scourge of rightwing bunkum), had ...
August 3rd, 2016
# Is Docker ready for production?
I prefer uberjars to Docker, and I prefer fat binaries, such as those allowed by Go, over Docker. And still there is the question “Is Docker ready?”
Senex says:
I’ve been tracking the beta for a while. I’m confused about this announcement. These issues still seem unresolved? (1) docker can peg the CPU until it’s restarted
(2) pinata was removed, so it can’t be configured from CLI scripts
(3) it’s not possible to establish an ip-level route from the host to a container, which ...
August 3rd, 2016
# Kent Beck suggests winter could come to the tech industry
Very interesting, especially since this is Kent Beck:
As a new millennium dawned, I was riding high. Extreme Programming was the flavor of the month, my price for consulting was crazy high and rising, XP Explained was a big hit. Two years later I was battling depression, I was burning through savings, and I couldn’t get a gig to save myself. In between I made bad decisions in a panic. It’s not the bad times that wipe you out, it’s the bad ...
August 3rd, 2016
# Crime is rising in the outermost suburbs
For a few decades after WW II the middle class of America operated under the rule “The cities are dangerous, the suburbs are safe”. Apparently that began to change after 1990:
The violent crime epidemic of the 1970s and 1980s was concentrated in big cities, and the crime decline that followed was concentrated there, too. As someone who lives in a big city and remembers the 1980s, I can attest that the change has been dramatic, almost miraculous. But if ...
August 3rd, 2016
# Flossing does not improve gum health
The British point of view:
The enthusiasm with which American dental professionals promote flossing despite the evidence, has raised the notion of a conspiracy with floss manufacturers. I don’t believe for a second that American dentists are in cahoots with floss makers, but why do they cling to the notion that floss is a good idea and keep recommending it? Perhaps because, like flossing, it’s a habit and after over a century of promoting the use of floss, it must be ...
August 3rd, 2016
# A Swede lands in Silicon Valley and is disappointed
A very interesting point of view:
I encountered levels of homelessness and mental illness that I was entirely unprepared for, but was repeatedly discouraged from donating any spare change by my new American community. It’s not your problem, that was the mantra that un-ironically flowed from the lips of entrepreneurs that otherwise convinced themselves that they were making the world a better place, presumably for themselves and the people who were their problem. There was something absurd and almost obscene about ...
August 2nd, 2016
# Why do people join hate groups?
This is an interesting article:
But it is problematic to use data garnered in externalist studies to draw conclusions about micromobilization since it is not possible to infer the motivations of activists from the external conditions in which the group emerged. Because people are drawn to far-right movements for a variety of reasons that have little connection to political ideology (Blee 2002)—including a search for community, affirmation of masculinity, and personal loyalties— what motivates someone to join an anti-immigrant group, for ...
August 2nd, 2016
# Grief regarding the end of the old political system
My sense is the changes will eventually involve fundamental constitutional revision. For now, people are talking about minor changes of policy:
The emergence of the Trump and Sanders insurgencies in the US, the Brexit vote in Britain, the formation of ultra-nationalists movements in Europe, are obvious markers of the new mood. The sea-change presents itself in different ways in different places. ISIS is a protest too.
Writers on the left have been taking positions on these issues for years, not ...
August 1st, 2016
# Why people hate Clinton
This is an interesting point of view:
My research indicates that the reality — the facts (I realize facts are immaterial when talking to many Trump supporters) — are that Hillary Clinton is one of the most honest politicians tracked by the Pulitzer Prize winning fact-checking project Politifact. I would also call upon Jill Abramson’s piece in the Guardian. Most of you probably know Abramson from the Wall Street Journal or the New York Times. Abramson writes:
As an editor I’ve launched ...
July 31st, 2016
# Square Space offers marketing nonsense when I want actual facts
Frustrating. Square Space offers a page remarkably free of any facts, which I suppose is meant to work as marketing, though it is so general and far removed from reality that it actually repels me from the service. I believe the line of reasoning was “Square Space exists to protect people from the technical details of building a website, so let’s avoid mentioning any specifics on the page about blogs” but in the end, a service does need to offer ...
July 27th, 2016
A very controversial idea, that is interesting nonetheless:
The root problem with Twitter is that the product is carefully engineered to cultivate maximum violence. Not intentionally, of course, but rather through a combination of early product decisions that were not re-visited, together with blind optimization of Twitter’s game mechanics toward vanity metrics. Twitter’s cultivation of violence, in turn, affects user engagement, user churn, the demographics of Twitter, and numerous other factors that have resulted in Twitter’s total failure to become a behemoth ...
July 27th, 2016
# How to package dependencies in Golang
Very interesting, as I’m a fan of the idea of “vendoring”:
An attempt to fix packaging in Go:
Manul is a vendoring utility for Go programs.
What’s the reason for yet another utility?
Because all other vendor utilities suffer from the following:
Some wrap the go binary and spoof the GOPATH env variable. You will have a non-go-gettable project which needs additional software in order to compile and run;
Some copy the source code of dependencies into the vendor directory:
It will be nearly impossible to find ...
July 26th, 2016
# Google Maps does not name Nachitschewan?
I can not find a zoom level where Google Maps names Nachitschewan. Is this a political thing?
Source
July 25th, 2016
# This is one dirty latrine
I’m trying to imagine how dirty a latrine gets after 220 years of use?
Cambridge researchers Hui-Yuan Yeh and Piers Mitchell used microscopy to study preserved faeces on ancient ‘personal hygiene sticks’ (used for wiping away faeces from the anus) in the latrine at what was a large Silk Road relay station on the eastern margins of the Tamrin Basin, a region that contains the Taklamakan desert. The latrine is thought to date from 111 BC (Han Dynasty) and was in ...
July 25th, 2016
# The advantage of a weight-balanced B-tree
A very interesting data structure of which I know nothing:
Source
July 23rd, 2016
# The rigidity of gender norms
An optimistic take would be that the people most willing to reconsider gender norms are non-conformists who see no need to get married. So the lack of flexible marriages doesn’t indicate a lack of flexible relationships. A very interesting article:
Bargaining models of the household assume that households are able to bargain – that men and women can change the way that they relate to each other; they can change the way that they spend money and allocate tasks. And ...
July 22nd, 2016
# Romance writers lead the way regarding self-publishing
And self-publishing offers both money and artistic freedom:
According to the nonprofit Romance Writers of America, around 82% of US romance book buyers are women, and 41% are between 30 and 54 years old. Most romance authors are female. Yet for a long time, the link between writer and reader was broken by a long chain of agents, publishers, promoters, and retailers.
Perhaps one of the most shocking revelations of today’s romance renaissance is that readers aren’t crazy about those raunchy ...
July 22nd, 2016
# A string of characters is best parsed using a finite state machine
I already knew this, but I don’t think I knew the extent of what was sacrificed to give Perl backreferences s:
Notice that Perl requires over sixty seconds to match a 29-character string. The other approach, labeled Thompson NFA for reasons that will be explained later, requires twenty microseconds to match the string. That’s not a typo. The Perl graph plots time in seconds, while the Thompson NFA graph plots time in microseconds: the Thompson NFA implementation is a million ...
July 22nd, 2016
# Zach Tellman on the benefits of a senior engineer
Tellman is interesting as always:
senior engineers choose companies with the right risks
Every company has different risks, and so every company expects something different from their senior engineers. An engineer who has spent the last five years making small, continuous improvements to the processes in a larger company may not enjoy or even understand the sort of role expected by a three person startup. The expectation that “senior” is a fungible title is both widespread and harmful, leading to unrealistic expectations ...
July 22nd, 2016
# The problems at Reddit
One individual speculated that the reemergence of the company’s drinking culture was to blame for the uncomfortable environment. Under Pao’s reign, Reddit tried to eradicate the bro-like amount of alcohol consumption at the office, but that went right out the window following Pao’s departure in July 2015.
“During all the leadership regimes, there were multiple incidents where employees would drink too much and end up in embarrassing and inappropriate situations,” a source ...
July 22nd, 2016
# Strong law is stronger than strong code
I have been following with interest the conversations regarding crypto-currencies. These seem to have a strong appeal to people of beliefs that might be described as “libertarian”. These people believe there is some way to escape the need to engage in political struggle with their fellow humans, some way to avoid all the mess of life and instead go away somewhere else, and build an alternative system with an alternative currency. But these people are always a part of this ...
July 21st, 2016
# The problems with Clojure
The conflict between Object Oriented Programming and Functional programming comes up a lot with Clojure, because to do any serious work you have to eventually use some Java, which takes you back into the world of Object Oriented Programming. This sums up my feelings:
The thing I like most about Elixir is the low friction between it and it’s host language, Erlang. Erlang is a functional language right from the start, and the BEAM is designed to run a functional ...
July 21st, 2016
# Milo Yiannopoulos is proving the power of the modern troll
Milo Yiannopoulos has a style and humor that could only work in the era of Internet. He first gained fame from Gamergate. Trolls need attention, but they also get attention for getting attention — that is, their fans are often minor trolls themselves, all hungry for attention, so they give props to the better trolls, for being good at it, just like a tennis player might admire another tennis player of exceptional skill.
Milo Yiannopoulos, a bleach-blond Brit whose ...
July 21st, 2016
# The RegX that killed Stack Overflow
A great post-mortem of a crash at Stack Overflow:
The regular expression was: ^[\s\u200c]+|[\s\u200c]+$Which is intended to trim unicode space from start and end of a line. A simplified version of the Regex that exposes the same issue would be \s+$ which to a human looks easy (“all the spaces at the end of the string”), but which means quite some work for a simple backtracking Regex engine. The malformed post contained roughly 20,000 consecutive characters of whitespace on a ...
July 21st, 2016
# The difference between Kafka and Kestrel
For my purposes, for the next 6 months, it seems that Kestrel will be all I need. I’d have to be very successful before I would need anything as complex as Kafka.
The biggest conceptual difference is that Kestrel is a simple stand alone queue where as Kafka is a full fledged queuing system.
Kestrel runs on a single machine and has no concept of clustering or failover or any other features you might expect in a queuing system. Instead the clients ...
July 21st, 2016
# Honey Lee Cottrell is dead
I haven’t read Susie Bright in a while, so I missed this:
Honey Lee was my second butch girlfriend, but she was my first famous love, my first older woman lover . At the end of our first date, she dropped me off on the curb and said, “Bye–You’re a nice kid.” I was put out by that, but I was dutifully intimidated. Honey Lee had already been partners with a string of women who were like the Who’s Who of ...
July 21st, 2016
# RabbitMQ is difficult, Kafka is awesome, Kestrel is beautifully simple
A great review of these 3 queues:
Not mentioned below is that RabbitMQ works hard to guarantee delivery of a message, so it is slow, but that is because it is in some ways doing more than Kafka.
RabbitMQ:
I created 4 queues, wrote a ruby client and started inserting messages. I got a publishing rate of about 20k/s using multiple threads but I got a few stalls caused by the vm_memory_high_watermark, from my understanding during those stalls it writing to disk. ...
July 21st, 2016
# Kestrel is as simple as Redis but Kestrel is an actual queue
I feel stupid that I didn’t look at Kestrel sooner. I feel especially stupid that I’ve been using Redis when I didn’t actually need it.
Redis has a beautifully flexible API which makes it tempting to use Redis for everything, but Redis is really a cache that focuses on speed above all else. Everything in Redis has to fit in memory, and Redis will drop anything that can’t fit in memory. Also, the stuff in Redis can be mutated, ...
July 21st, 2016
# Only use Amazon SQS if you need a high-latency high-concurrency service
Also interesting, don’t use Amazon SQS unless your needs fit this very specific model where you can deal with the latency and make up for it by being highly concurrent.
I just did some benchmarking the other day to compare Amazon SQS with RabbitMQ. Publishing and consuming 10,000 messages serially in 2 threads (one publishing the other consuming) on an EC2 instance took over 6 minutes using SQS and 12 seconds using RabbitMQ. I didn’t test ActiveMQ since their clustering is ...
July 21st, 2016
# For Apache Storm, use Kestrel
There is a lot in this thread that is interesting. This is coming from Nathan Marz, the guy who invented Storm. He says he uses Kestrel, so that is a big endorsement.
You want to make sure that your spout source can support the out of order acking that Storm requires for guaranteed message processing. We use Kestrel because it has this property and is the simplest. RabbitMQ is another good one to consider.
Source
July 20th, 2016
# The problem with RabbitMQ
Seems like RabbitMQ is good but not perfect:
Much like you’d chuck memcached on each of your web servers and access them in a ring, Darner can occupy a small niche on each box in your fleet’s resources. Tens of MB of RAM and negligible CPU opens up hundreds of gigabytes of queue spool per node. As queue size grows, memory usage remains constant.
Contrast this with Redis, which is speedy but limited in queue size to what will fit ...
July 20th, 2016
# ZeroMQ is the opposite of a queue
Reading this again, several years after the first time I read it, and now it occurs to me: I would use ZeroMQ only in exactly those situations where I would not use a queue. If I only need a queue, I can use Kestrel. But if I need some messaging pattern that is not supported by any queue, then I would use ZeroMQ. That is, if I had a truly unique situation that needed a unique pattern, then ZeroMQ would ...
July 20th, 2016
# Everything you need to know about queues
This looks like an amazing resource and I’m sure I’ll go back and read more soon.
Source
July 20th, 2016
# The New York Times uses RabbitMQ
RabbitMQ is written in Erlang, so I was inclined to think well of it, though I heard criticism of it. And then the New York Times used it. A very surprising vote of confidence in RabbitMQ:
This architecture – Fabrik – has dozens of RabbitMQ instances spread across 6 AWS zones in Oregon and Dublin. The instances are organized into “wholesale” and “retail” layers. Connection to clients is via websockets/sockjs.
Upon launch today, the system autoscaled to ~500,000 users. Connection times ...
July 20th, 2016
# Gauges uses Kestrel which is based on work from Blaine Cook
Why does Kafka get all the attention if Kestrel is so reliable? I assume this is because Kafka can do so much more, though of course the devops work of Kafka can be frightening. I didn’t know about the Blaine Cook connection (of Twitter fame):
Before I get too far a long with this fairy tail, let’s talk about Kestrel — what is it and why did I pick it?
Kestrel is a simple, distributed message queue, based on Blaine Cook’s ...
July 20th, 2016
# Kestrel versus Resque
Interesting note about these queues, which certainly convinces me to use Kestrel:
There are a lot of things that could be done with either Kestrel or Resque. Because Resque is backed by Redis, you have to remember that all of the messages waiting to be processed have to be able to fit in the RAM of the Redis server, with Kestrel you could queue millions or billions of messages and then start to pull them off.
The biggest difference between the ...
July 20th, 2016
Very worrisome, though no sane person would use MongoDB to track something involving money. That’s simply not what MongoDB is for.
Read uncommitted allows all kinds of terrible anomalies we probably don’t want as MongoDB users.
For instance, suppose we have a user registration service keyed by a unique username. Now imagine a partition occurs, and two users–Alice and Bob–try to claim the same username–one on each side of the partition. Alice’s request is routed to the ...
July 20th, 2016
# How to return a disallowed field in GraphQL
Best Practices for GraphQL are still in a very immature stage, but these two ideas both have some merit:
First, return null for the requested field. This seems to work well in cases where there is no real harm in asking for a particular set of data and no real harm in denying it.
A good example would be asking for the email of a user where the backend only provides the user’s email to that user themselves. If I request my ...
July 20th, 2016
# Why has Google released gRPC
This is interesting:
Google has been using a single general-purpose RPC infrastructure called Stubby to connect the large number of microservices running within and across our data centers for over a decade. Our internal systems have long embraced the microservice architecture gaining popularity today. Having a uniform, cross-platform RPC infrastructure has allowed for the rollout of fleet-wide improvements in efficiency, security, reliability and behavioral analysis critical to supporting the incredible growth seen in that period.
Stubby has many great features – ...
July 20th, 2016
# An app to pay women for emotional labor
The modernization of the economy constantly brings forth new specialities that are at first astonishing, and in particular, previously unpaid work joins the wage economy. That trends is 500 years old. Women used to create all clothing at home, now clothes are created in factories, and sold in exchange for money.
So what about the emotional labor of trying to make a date work? Here is a type of work that somewhat overlaps with therapists and prostitutes.
Getting exactly what ...
July 20th, 2016
# Brad Sester is writing in public again
Brad Sester wrote a column on the world economy, all through the build up to the Great Recession. I read him all through 2007 and 2008. Then he went to the Financial Times and his writing was behind a paywall, and I didn’t have a subscription. But now he is again writing in a place I can read him:
Turkey has long ranked at the top of most lists of financially vulnerable emerging economies, at least lists based on conventional ...
July 20th, 2016
# The Republican National Convention
I laughed:
Jenkins also reportedly asked the crowd to “raise your hand if you believe in science,” to which they responded with boos.
Source
July 20th, 2016
# Germs protect from allergies, biting nails helps
A very interesting theory:
When they tested at 13 for allergies to common things such as dust, grass, cats, dogs and molds, they found that 38% of those who had an “oral habit” tested positive — whereas 49% of those who didn’t suck their thumbs or bite their nails tested positive. This “protection” was still there at 32.
This fits with the “hygiene hypothesis,” which says that when children are exposed to germs early in life, their immune system gets trained to ...
July 13th, 2016
# Why I hate Ruby On Rails
I’m trying to help a friend with a very small Ruby On Rails project, where she needs a few elements of the interface tweaked. But this is Ruby On Rails, so of course I’m losing 3 hours trying to get setup. I’ve been drawn into the endless swamp of upgrading various libraries, which seems to be an automatic part of dealing with Ruby On Rails. If this was Clojure, or NodeJS, setup would have taken 5 minutes and I would ...
July 13th, 2016
# You are dragging this man by his ankles, through sliding glass doors down wide empty aisles
Isn’t this a brilliant opening paragraph?
You think: I want a flathead screwdriver. You imagine a large hardware store by your house. You are dragging this man by his ankles, through sliding glass doors down wide empty aisles, his pinkish, chewed down nails clacking against gray tile and his mouth still flapping though not saying too much of anything useful. In a word, blathering. Yammering. Prattling, etc. An unending tape loop of your yadda-yadda-yaddas.
That’s from Matthew Thompson. I worked with him ...
July 13th, 2016
# Why national legislators in the USA are ignorant about important topics
A very interesting article about the political process in the USA:
What now surprises me is when I come across a member of Congress who really does understand a particular issue in detail. And this sometimes does happen. Little pockets of expertise are scattered hither and yon all throughout Capitol Hill — especially when members dig in to work on idiosyncratic pieces of legislation that are off the radar of big-time partisan conflict. But on most issues, most of the time, ...
July 13th, 2016
# Mixins are harmful — the Javascript edition
Over the years there have been arguments against mixins, but the dominance of Object Oriented Programming meant that mixins still survived and had theoretical justification. Now, the spread of the Functional Paradigm has put renewed pressure on mixins. Dan Abramov at Facebook just came out with an essay against mixins:
“How do I share the code between several components?” is one of the first questions that people ask when they learn React. Our answer has always been to use ...
July 13th, 2016
# I am selling WPQuestions.com
I haven’t had the energy to make a successful business out of wpquestions.com, so I am going to sell it. Anyone interested should contact me.
I am selling the domain and the software and the datbase — the whole site.
June 30th, 2016
# The Agile process of software development is often perverted by sick politics
For those of you who don’t want to read this whole essay, here is the summary:
The word “agile” has a plain meaning in standard English, and that meaning was considered something positive by software developers, so much so that the most successful new development process of the last 30 years calls itself “Agile”. However, at many of the companies that I have worked, actual agility is suppressed because of various political factors. Fear wins out over trust. Instead of actual ...
June 30th, 2016
# The whole publishing industry depends on Barnes and Noble
If Barnes & Noble were to shut its doors, Amazon, independent bookstores, and big-box retailers like Target and Walmart would pick up some of the slack. But not all of it. Part of the reason is that book sales are driven by “showrooming,” the idea that most people don’t buy a book, either in print or electronically, unless they’ve seen it somewhere else—on a friend’s shelf, say, or in a bookstore. Even on the brink of closing, Barnes ...
June 29th, 2016
# In Pergamon there is a huge marble altar, forty feet tall with large sculptures: it also includes a Gigantomachy (Battle of the Giants)
This sounds amazing:
In January 1880 the great Russian novelist Ivan Turgenev, author of Fathers and Sons and one of the most cosmopolitan Russian writers of the time, was visiting Berlin, when he paid a visit to the Altes Museum. What he saw there not only made a profound impression upon him personally but marked the beginning of a momentous transformation in European understanding of the art and culture of the ancient Mediterranean world. He had been standing before a group ...
June 29th, 2016
# Ленин — гриб
I would say this is an example of how dangerous it can be to remove all humor from a medium — people become more vulnerable to hoaxes:
Lenin was a mushroom (Russian: Ленин — гриб) was a highly influential televised hoax by Soviet musician Sergey Kuryokhin and reporter Sergey Sholokhov. It was first broadcast on 17 May 1991 on Leningrad Television.
The hoax took the form of an interview on the television program Pyatoe Koleso (The Fifth Wheel). In the interview, Kuryokhin, ...
June 29th, 2016
# How much time and energy should a computer programmer spend learning a proprietary server system?
By itself, this is an anecodote about Google’s particular system: (but see my point at bottom)
Is there a lesson in this? Well, if I were in the business of programming Google App Engine, a few days’ effort up front to get it going might seem not to be a big deal. However, when I visit a team who have just added a new person, I invariably find that person struggling to set up their workstation. There’s usually someone in the room ...
June 29th, 2016
# If equity is compensation, can an employer ever take back compensation?
This is a very emotional point that comes up when a company pays workers with equity:
Scott’s post genuinely makes me angry. It uses subtle language to imply that employees are inferior individuals who are lucky that the owners of capital deign to share anything with them.
In Scott’s worldview, choosing to leave a company before it has exited is inherently disloyal. Even if they’re paying you under market. Even if you could contribute more value elsewhere.
I wonder if he would accept ...
June 29th, 2016
# Is Phoenix going to take over the tech industry?
If not, why? This has been one of the big puzzles of the last 30 years: if some technologies are clearly superior, then why don’t they take over? Apparently because they lack an element that appeals to management in big corporations? That’s always been the argument against Lisp: it is great for the individual master craftsman, but it doesn’t work in a big corporation full of badly paid, mediocre programmers.
Erlang has been the most safe, resilient technology out there ...
June 29th, 2016
# That strange isolation of raising kids
Very interesting:
Pregnancy and motherhood can be both a source of social detachment and foster an intense need for community, all at once. I’ve never felt simultaneously so siloed and also so much a part of the fabric of humanity than I have this past year, which hit me with endless contradictions. Pregnant, I felt incredibly special and also like a freak. I felt like an assembly-line conformist breeder and also an earth mama gushingly, glowingly, united with the cosmos (“like ...
June 29th, 2016
# Maybe students and professors need to push back against the University?
This is interesting:
I study Classics professionally, so I have more at stake in this issue than most. I taught Antigone just last semester. And I hope that students never stop being disturbed by it. If you’re mocking students for having a strong emotional response to that text, you haven’t read it. (It should but doesn’t always go without saying that, if you haven’t read something, you have no right to an opinion on its appropriateness for the classroom, particularly ...
June 29th, 2016
# The importance of taking a break
Such a good point about burnout and mental health:
I’ve definitely burnt myself out in the past. I’ve often worked morning till late night, most of the time, for months (years, since the breaks didn’t feel like they really counted?). And before that, being a broke student working multiple jobs wasn’t exactly great in terms of stress.
Part of me looks back and realizes that this is partially my fault, partially my managers’. The senior people around me also worked a ...
June 29th, 2016
# Merav Michaeli changes the Hebrew language
What an interesting fact:
Michaeli has long lobbied for action against sexual harassment and sexual assault, and has urged Israeli women to refrain from getting married until civil marriage is an option (in Israel, the rabbinate has jurisdiction over such matters; women married under Jewish law cannot get a divorce unless their husband agrees to it); she recently passed legislation creating alternative dispute solutions for couples seeking divorce. Perhaps most interestingly, she has had a remarkable influence on the Hebrew language ...
June 29th, 2016
# The arrogance of computer programmers
I think there is something to this:
As computer programmers, our formative intellectual experience is working with deterministic systems that have been designed by other human beings. These can be very complex, but the complexity is not the kind we find in the natural world. It is ultimately always tractable. Find the right abstractions, and the puzzle box opens before you.
The feeling of competence, control and delight in discovering a clever twist that solves a difficult problem is what makes being ...
June 29th, 2016
# Niche content plays that I was not aware of
I stumbled upon this site and it seems like a Tumblr blog, but apparently it is business that tries to make money. . My first reaction is “There is no way this will work”. I will check back in a year. I like to track these things, because I learn so much when it turns out that I am wrong.
Source
June 29th, 2016
# Why the public no longer listens to economists
Another interesting article:
One reason for the lack of faith is the failure to predict the Great Recession, but the public’s dismissal of macroeconomists is based upon more than the failure to foresee the dangers the housing bubble posed for the economy. It is also due to false promises about the benefits to the working class from globalization, tax cuts for the wealthy, and trade agreements – promises that were often used to support ideological and political goals or to serve ...
June 29th, 2016
# Which groups of people benefit most from global trade
This is an interesting article:
Economists have long predicted this sort of convergence. Observing how U.S. states tended to have more similar income levels over time, economists such as Robert Solow built models in which fast catch-up growth eventually leads to a more equal world. But the stubborn failure of global incomes to converge defied the theory, and economists were forced to accept the idea that countries’ differing institutions created differences in their long-run economic potential. That was a somewhat unsatisfying ...
June 29th, 2016
# Everyone who becomes a writer becomes a writer in their own way
A very interesting article:
I do not recall the exact moment, but I do remember the awkward conversations during the most self-doubting times. There was, for instance, the dinner party where my friend, the hostess, seated me beside a Pulitzer Prize-winning author as if we had something in common. I had recently finished the first draft of a novel, and on my desktop floated the files of a dozen or so essays that were in the process of being ...
June 29th, 2016
# What it is like to tutor the wealthy and the privildeged
An interesting article, from a tutor, about the way wealth sometimes protects mediocre students, and allows them to get into good colleges:
Because UT Austin is a terrific place—the rare kind of school that radiates both capaciousness and prestige—it is the top choice for many Texas high school students, and its unique admissions policy carries a lot of weight. It is discussed ad nauseam during application season; however, the reasoning behind this policy—behind the 10 percent rule, behind affirmative action—is not. ...
June 25th, 2016
# What age group stans on social media?
When the blogosphere was at its peak in 2005, I noticed that people only started blogging on political topics when they were about 24 or 25. If they were 18 or 19, large-audience blogging made no sense to them. At 18 or 19, what they wanted was a blog for their personal friends. They might have had a LiveJournal blog, and they expected a few of their friends to follow their diary. But blogging for a bunch of adults who ...
June 23rd, 2016
# How can you not mention the writer and singer of a song?
I know the music industry is screwed up, but I’ve never seen this before. I listened to a woman singing a song credited to Calvin Harris and I wondered “Who is singing?” since it clearly wasn’t Harris. Apparently others are wondering too, because I found this article.
Source
June 23rd, 2016
# Pagination with React / Relay / GraphQL
This is an awesome article:
Relay proposes a standard to define a has-many relationship for a GraphQL field. This standard defines a common structure that allows Relay to paginate and filter the results in an efficient way by using cursors, which I’ll explain in a bit.
This is the definition of a Relay connection (from the Relay connection specs):
Relay’s support for pagination relies on the GraphQL server exposing connections in a standardized way. In the query, the connection model provides a standard ...
June 21st, 2016
# The dreamers of the Web are still dreaming
There is an effort to break open the closed silos of the Web:
Today’s Web has a number of problems, the attendees agreed; the most obvious being the kind of surveillance uncovered by Edward Snowden’s revelations and the ability to block access, like China’s Great Firewall.
Tim Berners-Lee, who founded the Web and is now director of the World Wide Web Consortium, pointed out how far it has strayed from the original dreams for the technology. “That utopian leveling of ...
June 21st, 2016
# VioletBlue writes of being harassed by Jacob Appelbaum
I am worried about psychopaths like Appelbaum and how they manage to go on with their harassment, year after year:
When Jake got hired, he started giving tours. I only went on one of them. I had invited my editor and colleagues from the Chronicle to that happy hour, and we decided to go with him when Jake began leading people through the buildings for his tour. Kink’s main offices at that time were a wide, open-plan floor, with no ...
June 19th, 2016
# What is a comic book?
Vox has an article that is suppose to list the best comic books being created right now. The list seems to be limited to USA creations, which is surprising given how much Japanese manga has become a part of what we consume, when we consume comics.
Suppli isn’t there.
Silent Voice isn’t there.
There is an abundance of good material coming from Japan. I can not possibly list all of the great publishers.
But whatever you might think of as ...
June 16th, 2016
# The world is full of buggy jobs boards
If I go here:
https://www.themuse.com/jobs/yodle/full-stack-engineering-manager-20d14e
and click “Apply” then I end up here:
Cleary, something is broken.
“Full stack engineering” become “Director of Sales”?????
Source
June 15th, 2016
# When your trusted friends take the side of a charming psychopath and gang up against you
Wow, this is a very sad and shocking story:
Because the last thing anyone needs is to be targeted by Jake Appelbaum, I purged everything this person and sent and refused to hand over anything on privacy grounds. I explained what my reasoning was for doing what I did, was chastised further, let it go and considered the matter over.
But really, I thought, why would Jake be so defensive about some random LT that might have otherwise gone completely unnoticed? ...
June 15th, 2016
# Trolling is more and more a professional specialty
A few years ago, Jamie Bartlett, a social media analyst and author of The Dark Net, met up with the man behind a popular online white supremacist account in the UK. The meeting took weeks to set up—numerous calls and emails were exchanged before the man (whom Bartlett calls “Paul”) agreed to meet him in the small northern English town where he lived. When the two finally linked up, Bartlett said he was surprised to find that the ...
June 15th, 2016
# Demanding ssh key login to a server is safer than allowing passwords
This is good and true:
Require ssh key authentication
We tend to avoid passwords for logging into servers. There was a lot of discussion around this after Bryan’s original guide came out, but I tend to fall into this camp as well. Here are a few notes on this:
Passwords can be brute forced. Guessing a public key is so essentially impossible that they can be considered perfectly secure
What ...
June 15th, 2016
# Every manager needs to get better at firing people, because they always wait too long
The most common advice that I give to managers is “You need to fire more quickly”. It’s the most common advice I give because it is advice that managers do not want to listen to. Even supposedly “tough” managers hesitate far too long before firing people.
Apparently similar advice was given at Netflix:
McCord also convinced Hastings that he should ask himself a few times a year whether he would hire the same person in the same job if it ...
June 15th, 2016
# When a pregnancy isn’t viable
What happened at 31 weeks?
We went back to get a growth scan, and we saw the growth had fallen off a cliff. And this was the first time that we had been presented with this idea that there was something deeply wrong with the baby that had nothing to do with me. Until that point, all the really bad news had been with me, and my weird body. He had been thriving despite the environment.
But on ...
June 14th, 2016
# The NYC.gov website is full of bugs and errors
I tried to apply for a job here and the site was full of errors. They should hire me so I can fix this awful mess:
As to the following error:
(please note that all I was doing was uploading a tiny text file that was 315 bytes of information)
Incredible that anyone gets through this process:
Source
June 14th, 2016
# Tech forums can be nasty
And Hacker News is already a million times better than places like Reddit. We need more diversity in tech, but some folks seem willing to undermine the project of reforming the industry. I still see comments like:
He was privileged to be a black man since this drastically improved his odds of getting into Princeton. It’s not anywhere near as much of an achievement as you are making it out to be.
As of 2006, between 2/3 and 5/6 of black ...
June 14th, 2016
# Mother and daughter and a short skirt
Just now. At the corner of Broadway and 96th street in New York City, daughter is 12 or 13, mother is 40 or 45, they are talking about a woman they just passed, who did not notice them. The woman was perhaps 20 and was wearing a red dress and holding a black purse.
Daughter: I so love her purse! And that dress! Such an outfit!
Mother: It was too short.
Daughter: And the fabric and…
Mother: It was too short.
Daughter: … the earrings ...
June 14th, 2016
# A screaming lunatic
True story:
Yesterday I went to the park along the Hudson River, near 96th st, and I started running north. I do a circuit up to 125th st, then back down to where there is construction around 88th st, and back, about 8 kilometers total. The path on the right side is sometimes for bikes and sometimes for a mix of bikes and pedestrians.
I’m running north and there is a guy on a bike coming toward me. He is extremely ...
June 14th, 2016
# Object/Relational Mapping is rarely worth it
I think this can be stated simply: for your basic operations (CREATE, UPDATE, READ, DELETE) then an ORM offers some convenience. But ORMs break down as soon as you have a complex query. And yet, if you start using an ORM because it helps you with the simple queries, it will seem natural to you to extend it and try to use it for the complex queries.
This is a strained analogy to the Vietnam war:
Object systems are typically characterized ...
June 11th, 2016
# Math is confusing even for those who are good at it
Always be learning:
Many people who are in this position, trying to learn mathematics on their own, have roughly two approaches. The first is to learn only the things that you need for the applications you’re interested in. There’s nothing wrong with it, but it’s akin to learning just enough vocabulary to fill out your tax forms. It’s often too specialized to give you a good understanding of how to apply the key ideas elsewhere. A common example is learning very ...
June 11th, 2016
1 Comment
# AWS is inappropriate for small startups because its complexity demands a specialist
Sean Hull references a conversation that he and I had in Slack. I would like to expand on the argument that I made then. You might want to read his essay first, where he makes these points about AWS:
1. Over 70 services offered
2. Still complex to build high availability
3. Need a dedicated devops
4. Orchestration involves many moving parts
5. Troubleshooting failed deployments is difficult
At the time of our conversation I had crashed an AWS instance and we were having trouble fixing ...
June 11th, 2016
# GraphQL is the best thing about React / Relay / GraphQL
React / Relay / GraphQL:
The big breakthrough here is obviously GraphQL. Not React or Relay, since there are many competing implementations that do similar things, but GraphQL. Even though there are graph query languages out there (Gremlin, etc) they were not suited to querying JSON over the wire. GraphQL is ideal. For my next project, I hope to do a Clojure implementation of most of GraphQL, because I think it can be married to Om.Next in a very powerful way.
Actually, ...
June 11th, 2016
# Inemuri
Interesting:
However, this experience of sleeping in the presence of others as children is not sufficient on its own to explain the widespread tolerance of inemuri, especially at school and in the workplace. After some years of investigating this subject, I finally realised that on a certain level, inemuri is not considered sleep at all. Not only is it seen as being different from night-time sleep in bed, it is also viewed differently from taking an afternoon nap or power nap. How ...
June 11th, 2016
Source
June 10th, 2016
# Krubner, you saved my day
Aw man, after all the mistakes I make, it is nice to know I help people sometimes:
Source
June 10th, 2016
# Sometimes I make a bad decision
It’s very, very, very rare, almost unheard of, but sometimes I make a mistake.
I was helping at Open Road this spring. Sean Hull was also helping. Open Road runs a bunch of WordPress sites, such as The Line Up. All of the images for these sites were stored on a central NFS server. All of the machines were starving for hard disk space. The previous Director Of Technology had made many, many bad decisions, including the decision to save ...
June 7th, 2016
Interesting:
“Recovery,” “permanently ruined”—these are not words one typically encounters when discussing a contemplative practice.
On a cold November night last fall, I drove to Cheetah House. A former student of Britton’s, I joined the group in time for a Shabbat dinner. We blessed the challah, then the wine; recited prayers in English and Hebrew; and began eating.
Britton, an assistant professor of psychiatry and human behavior, works at the Brown University Medical School. She receives regular phone calls, emails, and letters ...
June 7th, 2016
# The thugs in Russia
There is a worrisome authoritarian movement in Russia. Many of its members are known criminals. They go after anyone who is vulnerable, just to demonstrate their contempt for the rule of law.
Datsik has a huge criminal background. He is an ex-fighter and boxer. Datsik has been imprisoned several times. He is a former member of the ultranationalist Slavic Union, which has similar political ideologies as Nazi Germany. The Slavic Union was banned in Russia because of their promotion of ...
June 7th, 2016
# Anna Rose Holmer is a genius
I saw a screening of this movie at the Gawker offices. I loved this movie. And Royalty Hightower is an amazing talent.
ANNA ROSE HOLMER: We started to talk about the film as a coming of age film—and even now, I’m so hesitant to use that phrase because it comes with a lot of baggage, particularly for stories about girls and young women. I think often it’s placed like five years later when you’re talking about sexual awakening, the idea that ...
June 7th, 2016
# The Belief that Tests are Smarter than Code Telegraphs Latent Fear or a Bad Process
This part is really good:
Programmers have a tacit belief that they can think more clearly (or guess better) when writing tests when writing code, or that somehow there is more information in a test than in code. That is just formal nonsense. The psychological perspective is instructive here, and it’s important because that — rather than any computational property — most drives developer behaviour. If your coders have more lines of unit tests than of code, it probably means one of several things. They may be ...
June 7th, 2016
# The problem with unit tests
Interesting:
Unit testing is of course not just an issue in object-oriented programming, but the combination of object-orientation, agile software development, and a rise in tools and computing power has made it de rigueur. As a consultant I often get questions about unit testing, including this real one from a recent client of mine, Richard Jacobs at Sogeti (Sogeti Nederland B.V.): My second question is about unit tests. If I remember correctly you said that unit tests are waste. First, I was surprised by that. Today however, my ...
June 6th, 2016
# Ruby On Rails is obsolete
This is a strange conversation to be having in the year 2016. Ruby On Rails changed the technology industry in 2004, but it can not claim to be winning in 2016. It still lacks a story for concurrency. It is being undermined by 2 forces:
1.) the need for concurrency, which is offered by other eco-systems, such as those that run the JVM. A language like Clojure offers the high level of meta-programming that Rubyists love, but with the vast arsenal ...
June 6th, 2016
# What does it mean for a criminal to express remorse?
Interesting:
I fully respected his right to a trial, but even after twelve jurors unanimously convicted him guilty of three felonies, all he has admitted to doing is ingesting alcohol. Someone who cannot take full accountability for his actions does not deserve a mitigating sentence. It is deeply offensive that he would try and dilute rape with a suggestion of promiscuity. By definition rape is the absence of promiscuity, rape is the absence of consent, and it perturbs me deeply ...
June 6th, 2016
# Elite conservatives attack the white working class
I am altogether amazed at the fissures opening up in the conservative coalition in the USA. The coalition came together after 1958, and has been the dominant voice in the USA since 1968. But that era appears to have ended.
My childhood was different from Kevin’s, but I grew up in Kentucky, live in a rural county in Tennessee, and have seen the challenges of the white working-class first-hand. Simply put, Americans are killing themselves and destroying their families at ...
June 6th, 2016
# Fighting against poverty, yet indulging in corruption
The progress is great, but the money wasted on corruption is very sad:
The outsiders’ view of Rio de Janeiro—sexy beaches and city slums—make an incomplete sketch of the country. 193 million Brazilians live outside of Rio, many of them digging into the ground for water, using a community phone to receive calls, and walking long distances to catch buses to banks, where they stand in line for hours while awaiting the government assistance promised by the Worker’s Party.
Many Brazilians would ...
June 6th, 2016
# What makes a great fake viral story
Interesting:
And then there’s the anecdote, which feels like a mini-drama in and of itself. Act 1: A young, beautiful woman auditions for a part. We know, because of the face of this young woman and the connotation of actorly dominance that it has come to carry, that she was, without question, good enough for the role. Act 2: The people making the film think she’s not beautiful enough. She was, or theoretically was, sent to the precipice of disbelief: the ...
June 6th, 2016
# How moderation grew up on the Internet
Interesting:
Mora-Blanco’s team — 10 people in total — was dubbed The SQUAD (Safety, Quality, and User Advocacy Department). They worked in teams of four to six, some doing day shifts and some night, reviewing videos around the clock. Their job? To protect YouTube’s fledgling brand by scrubbing the site of offensive or malicious content that had been flagged by users, or, as Mora-Blanco puts it, “to keep us from becoming a shock site.” The founders wanted YouTube to be something ...
June 3rd, 2016
# Sexual ideas you should really avoid
This is funny. 33 things that happen in porn that you should never try yourself:
Spying on someone in the shower while assuming voyeurism turns them on
Picking someone off a street in your van
Sex with a strange pizza guy, plumber, electrician, or anyone else who’s paid by their employer to go to your house
Answering the door in only a towel
Answering the door completely naked and not expecting it to end ...
June 3rd, 2016
# The way Trump is changing politics in the USA
In his excellent book Parting The Waters, Taylor Branch makes the point that the riot that occurred in Oxford, Mississippi (over the arrival of James Meredith) on September 30, 1962 was the last large scale white racist gathering in the USA for several decades. And for some decades, it seemed that there had been a permanent change in the USA, that such things would never happen again. And certainly, the Republican leadership would not allow such things, for a long ...
June 2nd, 2016
# Pure objectivity in news is an impossibility
This is good:
Pure objectivity in news is an impossibility, and pursuit of such pure objectivity is a fool’s errand. As you pointed out, the editorial process in which a selection is made between newsworthy items is highly subjective. Every day only a few news items make it onto the front page, and there cannot possibly be a neutral metric that can determine which ones. Journalism doesn’t just provide the facts, it also has an obligation to educate and inform the readers. Impartiality ...
June 2nd, 2016
# Sometimes peer review delays progress for many decades
This is what real leadership looks like:
Morris intentionally consumes H. pylori. Like Marshall, he becomes ill, but unlike Marshall, he is not completely cured by antibiotics. The infection will remain with him for three years.
I wish he had been given a medal for his self-sacrifice. He was attempting to save millions from suffering.
Interesting, though very disappointing:
1881 Klebs notes the presence of bacteria-like organisms in the lumen of the gastric glands.
1889 Walery Jaworski describes spiral organisms in sediment washings ...
June 2nd, 2016
# The diverse factions of the progressive movement in the USA during 2016
Interesting:
1.Genuine idealists: For sure, quite a few Sanders supporters dream of a better society, and for whatever reason – maybe just because they’re very young – are ready to dismiss practical arguments about why all their dreams can’t be accomplished in a day.
2.Romantics: This kind of idealism shades over into something that’s less about changing society than about the fun and ego gratification of being part of The Movement. (Those of us who were students in the 60s and ...
May 29th, 2016
# Zana Vrangalova’s research on human sexuality
A very interesting research project:
Still, the site is far from clinical. The home page is a colorful mosaic of squares, color-coded according to the category of sexual experience (blue: “one-night stand”; purple: “group sex”; gray: the mysterious-sounding “first of many”; and so on). Pull quotes are highlighted for each category (“Ladies if you haven’t had a hot, young Latino stud you should go get one!”). Many responses seem to boast, provoke, or exaggerate for rhetorical purposes. Reading it, I felt ...
May 24th, 2016
# Math papers are hard to read because people invent their own syntax
Obviously professional mathematicians need the power to continue to create new syntax. But should there be a syntax for creating syntax? I’m thinking of Lisp programming languages, that allow a programmer to invent new syntax, but enforces some rules along the way. One counter-argument, to applying such reasoning to math, is that vernacular languages, such as English, can be used to describe any syntax. But that is surely cheating: if math is to be a language, then the syntax for ...
May 22nd, 2016
# Why does Rails become awful?
Interesting:
Let me tell you a story about what can happen in a convoluted Rails codebase. Once, I joined an existing project. It was a huuuuge app which was running an on-line shopping community website. Complicated sales model, complicated promotions, complicated product setups, coupons, user groups, messages – it had it all. I joined them to help ship a few new features. One of my early tasks was to…add a link to something on some page. It took me few days ...
May 15th, 2016
# Chronological feeds are being replaced by algorithms
Any algorithm can be gamed, so Facebook and Apple and Google are actually increasing the number of ways that content pushers can manipulate the system.
The feed is dying. The reverse-chronological social media feed — the way you’ve read Instagram, Twitter, Facebook, and blogs (which is to say, the internet) at various points over the last decade, updates organized according to the time they were posted, refreshed at the top of the screen — no longer really makes sense. The ...
May 15th, 2016
# Angry while female
Interesting:
Why, asked thousands of Twitter and Facebook users, can’t a woman be outraged without being labeled a diva?
Anger, as we have been told ad nauseam during this election cycle, is the driving force of American discourse, the bond that unites supporters of billionaire dabbler Trump with the earnest progressives behind Sen. Bernie Sanders. It fuels our commentary, our comedy, our drama, our love of social media. At worst, we have become a nation of venters, easily provoked and quick ...
May 15th, 2016
# The dumbest name for a good architecture is “serverless”
I strongly agree that the idea is good, but the name “serverless” is really stupid:
So… this is backend infrastructure (i.e. it runs on a server) to let your team deploy “severless” apps…
So they’re serverless. Except the server you’re running it on. And the lamba/style code they wrote and uploaded to it.
But serverless, because no ops staff required. Except the ones who installed and maintain this.
This is like a snake eating its own tail and wondering what hurts.
Edit: despite my sarcasm, ...
May 15th, 2016
# The next wave of layoffs in tech
Interesting:
However, every time there is a great deflating, it is because the market is tired and preparing to embrace something different. So far I’ve been through several of these, chips in the 80′s dot coms in the late 90s, storage in the early 2000′s, and now either web 2.0 or social (depending on how you score it). Three threads are competing for the next round, IoT, Machine Learning, and Bioinformatics. CRISPR derived technologies could be in there too but ...
May 15th, 2016
# Who is Christian?
Interesting:
While the amount of constituents there is growing by the day, numbers in the West (the United Kingdom and United States, in particular) have nosedived in recent years, some 25 percent from 1972 to 2002, according to the Friends World Committee for Consultation.
Source
May 14th, 2016
# You rarely hear about how truly fucking brutal it is
I love this, so very true:
Usually you read about startups on sites like TechCrunch where a startup in San Francisco made some app that does something inane like sends “Yo” to your friends and raises million of dollars their seed round that later sells for 100s of millions to billions of dollars. You rarely hear about how truly fucking brutal it is. It’s not the long hours that most founders say in interviews, it’s the mental anguish. The euphoric Mt. ...
May 14th, 2016
# Layers of abstraction build up in the financial world, just like they do in software
Interesting:
This is good and almost funny:
The financial system is built up in layers of abstraction over some vast and unwieldy machinery. The machinery is complicated in part in order to make the abstraction simple: You can buy stock with a click of a mouse because armies of people devote their careers to the legal niceties and operational maintenance and integration of all this back-office apparatus.
The boring details:
But usually it is more complicated than that. Mostly, it is inconvenient ...
May 14th, 2016
# Financial innovation is often just corruption by another name
In other words, LendingClub is an originator, funneling loans upstream to Wall Street firms. And in executives’ desire to grow amid demands from shareholders — LendingClub went public in 2014 — they began to exhibit the tendencies of the banks they sought to out-innovate.
First, Laplanche approached the board about investing in Cirrix Capital, an investment fund that actually bought a lot of LendingClub loans. If LendingClub invested in Cirrix, then Cirrix could invest more in LendingClub loans, a bizarrely circuitous ...
May 10th, 2016
# The sad, slow way a system of cron scripts becomes ugly
Do you have a chore that needs to run in the background, maybe once a day, or once an hour? Cron scripts will save you! They are the most amazingly amazing thing God has invented since Adam and Eve! For sheer wonderfulality they have no equal among the products of mortal fallen flesh!
At least at first.
The simple cron script is wonderfully direct and efficient. But the first can lead to a second. The second can lead to a third. ...
May 1st, 2016
# If women could be fathers
Cloning would have to be 100% safe, and so would extracting the male genes from a woman’s cell. But the technology is not yet ready, and I have trouble imagining that any government will give this line of research any priority. Because a lot of people are afraid of women having that kind of freedom. But this is what Shulamith Firestone dreamed of:
So that just as to assure elimination of economic classes requires the revolt of the underclass ...
April 28th, 2016
# Lying is a lot of work, especially in romance
Yes, the guy is trolling, but there is a grain of truth here. I do think lying requires a lot of work. For that reason, I avoid lying. I don’t have the energy for it.
I’m a corporate strategist so I approached my extramarital affair with an eye to the long game. I planned accordingly to have a mistress same as I planned years ahead to embezzle my retirement. Get married, share finances, and most importantly: have kids. Bind yourself ...
April 23rd, 2016
# Love is hard because everyone is crazy
Interesting:
In a wiser society, prospective partners would put each other through detailed psychological questionnaires and send themselves off to be assessed at length by teams of psychologists. By 2100, this will no longer sound like a joke. The mystery will be why it took humanity so long to get to this point. We need to know the intimate functioning of the psyche of the person we’re planning to marry. We need to know their attitudes to, or stance on, ...
April 23rd, 2016
# Weddings are not over
This is a very silly and stupid rant. This particular fight doesn’t really touch me directly. I’ve only been to two weddings in my life, for cousins, and I was young and I had to go. That was back in the 80s or 90s. But excess at weddings is likely to continue. Wealth in the USA is concentrating, and the working class no longer gets married, so marriage has emerged as a powerful status symbol. 50 years ago, when ...
April 22nd, 2016
# If your characters don’t interact then you don’t have a story
I love this:
Maybe it’s the rape, or the violence, or how it’s really boring. Everyone seems to have an opinion about why Game of Thrones, once a mesmerizing fantasy land that darkly mirrored modern day dilemmas, has become near unwatchable. (Which is not to say people have by any means ceased to watch it.) But there is one reason that rises above them all, and it is very simple.
Hardly any of the characters on Game of Thrones interact with each ...
April 17th, 2016
Funny:
Live from the Great Stagnation: Why in the past two centuries hasn’t there been a tea blend developed that I like more than Earl Grey? What is wrong with our innovation system—or with me?
Wikipedia: Earl Grey: “In one case study, a patient who consumed four litres of Earl Grey tea per day reported muscle cramps, which were attributed to the function of the bergapten in bergamot oil as a potassium channel blocker. The symptoms subsided upon reducing his consumption ...
April 10th, 2016
# What is education really for?
Interesting:
Forager children aren’t told what to do; they just wander around and do what they like. But they get bored and want to be respected like adults, so eventually they follow some adults around and ask to be shown how to do things. In this process they sometimes have to take orders, but only until they are no longer novices. They don’t have a single random boss they don’t respect, but can instead be trained by many adults, can select ...
April 10th, 2016
# What do AWS services actually do?
I love this:
Data Pipeline Should have been called Amazon ETL
Glacier Should have been called Really slow Amazon S3
Kinesis Should have been called Amazon High Throughput It’s like Kafka
I have used this but I did not know the name:
Snowball Should have been called AWS Big Old Portable Storage Use this to Get a bunch of hard drives you can attach to your network to make getting large amounts (Terabytes of Data) into and out of AWS It’s like Shipping a Network Attached Storage device to AWS
These are useful names that actually describe what ...
April 10th, 2016
# The rare moments I help someone
I wish I was more active helping out on open source projects. The few times I’ve contributed, advice or code, I tend to get positive feedback.
And my code suggestions are not wholly misplaced:
So really, why don’t I do this more often? I really am not sure. I suppose the desire to start my own business had me focus all my efforts on that, instead of the various open source communities?
Source
April 10th, 2016
# Femslash and the growing power of fandom
I’m not saying anything new if I say that fandom has changed the relationship between the reader and the author. I have the impression this change started in Japan and has been imported to the USA. That’s despite fandom mostly living on the Internet and the Internet having been mostly developed in the USA.
Fandoms influence on authors tends to be trivial. Two characters who have never kissed, but of whom there is slash fiction, end up kissing, and the ...
April 1st, 2016
# What does the word herbivore mean?
The herbivore serial killers:
He then spent six years in the Arapaho National Wildlife Refuge in Colorado, along with Charles Brown of the University of Tulsa, Oklahoma – and watched the squirrel death toll soar to 163.
“It boggles the imagination that something like that was going on under our noses and we didn’t notice,” says Hoogland. He describes the killings as “quick, subtle and unanticipated”.
While some prairie dogs chased the squirrels, others stalked them, waited outside their burrows or even ...
April 1st, 2016
# Planning the wedding a long time before the wedding
Interesting and funny:
OK here’s the thing. Knowing what you want to wear…. sure. Fine. Its a time you get to wear a pretty dress. But until you’re kind of close to the actual deal, I absolutely can’t stand it when women taaaaalk and talk about a wedding that isn’t even remotely on the map. I’m in a in a 6 year relationship that’s headed towards marriage; I love TV shows like Say Yes to the Dress – I still don’t ...
March 27th, 2016
# The fanaticism of “test driven development” is slowly fading
This was one of those trends that went too far and I’m glad to see people talking about reasonable limits:
If you’re part of the Ruby On Rails community for a long time, you’ve probably read tons of articles about testing Rails application (less these days, though). Although there always have been diverging opinions on the matter, it seems the common wisdom was to say that you had to test everything: models, controllers, views and full-stack tests. Oh, and you had ...
March 27th, 2016
# Automation is putting people out of work
This should frighten people out of their complacency. Also, the trend starts in1958, not 1976.
From Tyler Cowen:
You sometimes hear there is no evidence of automation putting people out of work, but arguably the automation of manufacturing, plus IT-enabled foreign competition, are significant factors behind this trend. This picture also casts doubt on the common view that there are hidden real wage increases, not picked up by standard data and wage deflators and the like. You would expect ...
March 27th, 2016
# The languages of politics
Conservatives prefer the certainty of nouns:
This use of nouns, rather than adjectives, is seen to preserve stability, familiarity and tradition – all of which appear to be valued more highly by conservatives than liberals.
Because nouns ‘elicit clearer and more definite perceptions of reality than other parts of speech’, they satisfy the desire for ‘structure and certainty’ that is common among social conservatives, the research authors found.
The research was based on studies carried out in three countries – Poland, Lebanon, ...
March 27th, 2016
# Churchill’s vivid writing
I’m coming back to writing lately, after 20 years, and I find that self-expression means very little to me now, whereas making money does, so I am much more interested in writing things that other people will find entertaining. So I can relate to this bit about Churchill’s writing:
In fact Churchill resigned from the Conservative front bench in the 1930s so he could earn more money as a writer and to some extent make up for these losses; that ...
March 26th, 2016
# Are bootcamps better than University?
My Europeans friends think its weird that universities in the USA insist that students take a wide range of classes. In Europe, university is seen as a time when one becomes a specialist in a particular skill. For instance, in Poland, it is common for a person to go to university for 5 years and graduate with the equivalent of a masters in a given field.
Especially considering how expensive university has become in the USA, asking students to take ...
March 26th, 2016
# Why are women paid less than men?
Interesting:
That sounds like a truism, but the academic work behind it helps explain the pay gap’s persistence even as the factors long thought to cause it have disappeared. Women, for example, are now better educated than men, have nearly as much work experience and are equally likely to pursue many high-paying careers. No longer can the gap be dismissed with pat observations that women outnumber men in lower-paying jobs like teaching and social work.
A new study from researchers at ...
March 26th, 2016
# RESTful APIs are dead, long live GraphQL
We can argue whether RESTful APIs ever existed, since very few ever implemented HATEOAS. Ruby On Rails claimed it offered RESTful APIs, but it never offered HATEOAS. After 10 years of failure, the world is looking for something new.
Interesting:
Imagine we have a simple application that fetches a list of stories, and some details about each one. Here’s how that might look in resource-oriented REST:
// Fetch the list of story IDs but not their details: rest.get('/stories').then(stories => // This ...
March 26th, 2016
# Picking React isn’t a technology decision, it’s a business decision
Interesting:
The clear winner right now, is React. Components all the way down makes your application much easier to reason about. The learning curve is very flat. The important APIs would fit on one page. JSX is awesome. You get all the power of JavaScript and its tooling when writing your markup. It is the natural match for Flux and Redux (more on that later). The React community is amazing, and produced many best of breed tools such as Redux (also more on that later). Writing high ...
March 26th, 2016
# Pay discrimination in tech
Women who write the software that runs on mainframe computers earn on average 72 cents per dollar earned by their male counterparts, according to research conducted by Glassdoor Inc., the online job information firm. That pay gap exists even after controlling for age, education, experience, job title, employer and location.
This suggests that the gap widens with age:
However, not all tech jobs pay men and women so differently. Among mobile developers, there is just a 2.9% gap between ...
March 26th, 2016
Everyone is laughing over this. An 11 line function as its own NPM module? I am unsure how I feel. The trend has been to smaller and smaller pieces of functionality. I don’t find this outrageous. Still, the parody is funny:
c4n4rd is game:
This is really exciting!!! I was a bit disappointed that the right-pad will be out only in 2017. I am looking forward to that release because there is a high demand for it now.
What kind of ...
March 26th, 2016
# null
Testing WordPress to see if a title of “Null” works.
Source
March 26th, 2016
# How long can an unsustainable economy grow?
Interesting, but wrong:
During the good times, “we always wanted to grow just a little more than we otherwise could.” There was always a reason why, if a little bit of growth was good, more would be even better. It was very easy to justify various kinds of mischief — from annual deficits to artificially low interest rates — in order to wring just a little more growth out of the economy. This is true whether your goals were motivated by ...
March 26th, 2016
# What name should the children get?
Interesting:
As my belly grew, the comments got even stranger. I had secretly hoped for no reaction, for our choice to be as common as saying, “I went with the mustard instead of the ketchup.” No reaction would mean something good, right? That women in this country are, for example, no longer considered the property of men, even in name. That archaic systems are truly collapsing. That we can reclaim language that was formerly used to control us.
But it seemed, ...
March 22nd, 2016
# The First Civil War may end in time for the Second
Yet another sign that people are increasingly ready to move beyond the First Civil War:
Maryland lawmakers took a step Thursday toward scrubbing references to “Northern scum” and other Civil War-era phrases from the official state song.
The Maryland Senate voted 37-8 for the changes, while also recognizing “Maryland, My Maryland” as the state’s historic song. Supporters of the measure, which now goes to the House, said it was a compromise that removes offensive language and recognizes history.
“They keep the historic ...
March 22nd, 2016
# History is not individuals
I’ve noticed this too. We’ve come a long way from Braudel:
As I more closely looked at the books displayed, I noticed a peculiarity. Almost all books … on the French, Russian and Chinese revolutions were not only critical of the revolutions, focused on the destruction they wreaked, but were exposés of their leaders, of their murderous natures and sexual perversions. Robespierre is a green-spectacled misanthrope who never had sex; Lenin hated people and loved only his mistress; Stalin was not ...
March 22nd, 2016
# The monoculture of tech
Worrisome and very true:
(3), combined with (1), gets at what TrendCo’s real complaint with Mike is. He’s not their type. TrendCo’s median employee is a recent graduate from one of maybe ten “top” schools with 0-2 years of experience. They have a few experienced hires, but not many, and most of their experienced hires have something trendy on their resume, not a boring old company like Microsoft.
Whether or not you think there’s anything wrong with having a type and rejecting ...
March 22nd, 2016
# The end of what was in San Francisco
Rarely does there seem so extreme a case of affluent people moving to a city because it seems creative, and then, by their own efforts, killing off the creativity.
I just can’t. I was born in San Francisco; my parents live there, today.
Gentrification is real and palpable. Once cozy neighbourhoods have become playthings for the rich and entitled. Where botánicas once opened their doors, now pricey designers have moved their precious boutiques. Where once a freewheeling, affordable, ...
March 18th, 2016
# The big trials remind us of the changing times
Oscar Wilde’s trial reminds us of where gay rights stood in the 1890s, his astonishingly bold defense of gay sex reminds us that Victorians standards were beginning to crack. Big trials do that, they make an era vivid. The same is true of the trial of O J Simpson, which reminds us of where race relations were in 1994/1995.
I’d forgotten how much Marcia Clark was herself put on trial during the trial:
But, surely, the hardest part ...
March 18th, 2016
# The end of the test-first mania
It worries me that the tech industry is driven by such intense manias, which have cost me several jobs. For a long time you were not allowed to question Object Oriented Programming. I still go to job interviews and I’m asked the basics of Object Oriented Programming, and it is clear I have to say nice things about Object Oriented Programming or I won’t get the job. Thankfully none of these people ever check Wikipedia, where I am cited as ...
March 18th, 2016
# How the movies talk about authoritarian tendencies
I don’t understand why the movies need to use superheroes to talk about these issues, but it is good they are talking about these issues:
Source
March 17th, 2016
# The new politics at National Review
There are some fundamentally new politics being expressed by the National Review. In some ways, these beliefs sound like the unpopular conservative beliefs of the era before 1958, which is basically the era before the National Review (which got going in 1955 and which helped launch the modern conservative movement). There is an aspect to this writing that expresses the contempt that wealthy Protestants expressed for the working class back in the 1800s. Really, this is a kind of politics ...
March 17th, 2016
# Onyx tested by Jespen is genius tested by genius
Good lord, this makes me happy. I think Michael Drogalis is a very smart guy and everyone knows that Kyle Kingsbury is a very, very smart guy. Kingsbury’s work on Jespen is the finest work that anyone has ever done on the problems of distributed data. Onyx is exciting as an a Clojure answer to Apache Storm. Sad to say, Storm is written in Scala. The idea of testing Onxy with Jespen is one of the finest ideas ...
March 17th, 2016
# How to erase a woman from her biography
To the extent that identity is imbued in the body and manifests as a nose or an eyebrow or a skin color, then changing a nose or an eyebrow or a skin color, even in subtle ways, can erase a person’s identity.
I do not believe and never said that the nearly all-white team behind film are out-and-out racists who sought to disrespect Nina Simone’s legacy. But, as Coates notes, “racism is a default setting,” and unless we are doing ...
March 17th, 2016
# Living Social has raised more than \$900 million to date
And it is dying. They just laid off more than half their staff. How do you gain so much investment and then die? Was the whole business opportunity a fad? An illusion?
Source
March 17th, 2016
# The new politics in the USA
This is worrisome:
Source
March 17th, 2016
# Dov Charney continues to self destruct
This is one of the more extreme examples of self destruction in recent USA business history.
Source
March 14th, 2016
Interesting:
Source
March 14th, 2016
# You can know someone day in, day out, love them completely and never really understand them
Interesting:
And that occurred to me over and over again as I read through the book. Couples tend have a lot of the same squabbles over money, domestic labor division, sex, free time, for a reason. But this book is not really a test of this couple; it’s a test of marriage itself. In a way, it’s an indictment of an institution that will take even the most easy going, low-key, adventuresome couple and leave them standing in the kitchen arguing ...
March 14th, 2016
# Unix processes have gotten bigger and slower over the years
Interesting:
The obvious question thus is: Why state machines? Why not processes or threads?
And the obvious answer is: Performance.
When UNIX was still young, scheduling was supposed to be done by the OS on per-process basis. When implementing a network server, for example, you were supposed to fork a new instance of the process for each TCP connection and rely on the OS scheduler to switch between the processes.
I guess it made sense from performance point of view back then. All ...
March 12th, 2016
# Had Linda been more confident, we’d have won
Interesting:
The other night, I was reminded that under-confidence also has costs. In our pub quiz one of my team-mates suggested several answers but with little confidence, causing our captain to choose other answers. However, she was right every time and our captain wrong. The upshot was that we slumped to an abject defeat to the bottom team in the league. Had Linda been more confident, we’d have won.
Is that right? Surely most of the blame attaches to the captain? What ...
March 10th, 2016
# Jakub Holý on copying :pre and :post conditions
Obviously I have read this article before (I offered response and was quoted before) but I’ve gone back to read it again and this jumped out at me:
Do you repeat the same checks again and again? Then you could either copy them using with-meta (they end-up in metadata anyway) or reuse the explicitly:
(defn with-valid-car [f] (fn [car] {:pre [:make :model :year]} (f car))) (def count-price (with-valid-car (fn [car] (do-something car)))) ;; or make & use a macro to make it nicer
That ...
March 10th, 2016
# Garth Greenwell talks about the importance, and the cost, of gay marriage
Very interesting:
I certainly was aware—and I was aware of this as a reader, and I was aware of this as somebody in the literary community—of this stigma about gay books. And I was also aware of a kind of gap between the generation of these trailblazers like Edmund White and Andrew Holleran, and my generation, in terms of those novels that document gay life at a particular moment. One explanation for that is very obvious: It’s AIDS.
Another explanation for that, ...
March 9th, 2016
# Sweden leads the world in the ratio of women to men getting college degrees
Interesting:
In 2013, six million students across OECD countries graduated from a higher education institution with a bachelor’s degree; 58% of them were women. This percentage ranges from 69% in Sweden [emphasis added] to 45% in Japan. Besides Japan, only Germany, Korea, Switzerland and Turkey still have more male than female graduates.
Source
March 9th, 2016
# The history of temporary workers
Interesting:
Northwestern Mutual was not unique. For instance, “a large Milwaukee bank” faced the rising challenge of data entry, but the cost of the machines to enter the data—“Comptometers”—was prohibitive. Instead of hiring more people to work during the day, which would have required more machines, the bank hired “several hundred temporaries [to work] during a short evening shift” doing the data entry on the machines that the permanent staff could not. The hours of expensive overtime became hours of cheaper ...
March 9th, 2016
Apparently this has gotten better under the new CEO:
In my (very-biased) opinion, I believe collaboration is fundamentally broken at Microsoft. It is all about politics, not great outcomes, and that is absolute death in a functional organization, which has nothing but collaboration to hold together cross-functional product teams. At least in a divisional model all of the relevant team members have a common product and a common boss, meaning everyone has no choice but to work together. Unless the employee ... | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.16177397966384888, "perplexity": 3838.7406095551264}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738663202.87/warc/CC-MAIN-20160924173743-00167-ip-10-143-35-109.ec2.internal.warc.gz"} |
https://math.stackexchange.com/questions/2913762/conditional-expectation-for-a-random-variable-with-infinite-expectation | # Conditional expectation for a random variable with infinite expectation
Let $(\Omega,\mathcal{F},P)$ be a probability space, $X:\Omega\to\mathbb{R^+}$ be a non-negative $\mathcal{F}-$measurable random variable with $E[X]=\infty$ and $\mathcal{H}\subset\mathcal{F}$ be a sub-$\sigma-$algebra. How can we show the existence of $E[X|\mathcal{H}]$?
For a real valued random variable with finite expectation I can understand the proof from wikipedia. It defines a measure $\mu^X:F\in\mathcal{F}\mapsto\int_F XdP$ and restricts it on $\mathcal{H}$. Then use the Radon–Nikodym derivative to show the existence. In case $E[X]=\infty$ the measure $\mu^X$ is not finite anymore. However, if we impose it to be $\sigma-$finite we can still use the Radon–Nikodym derivative.
I do not think it is true in general that such $\mu^X$ is $\sigma-$finite. Is there a way to show existence for such a random variable without this assumption?
• Perhaps you could look at $X_n=\min(n,X)$? – copper.hat Sep 11 '18 at 23:26
• When you say the existence of E[X|H], does E[X|H]=∞ count as existing? I would have thought no. And if the expectation is infinite then surely the conditional expectation could also be infinite, for some choices of H, in which case the thing you're trying to show isn't true. – Steven Irrgang Sep 11 '18 at 23:34
• If it helps, you can show in general that $\mu^X$ is $\sigma$-finite. – Mike Earnest Sep 11 '18 at 23:39
• @StevenIrrgang I think working on extended Real line, conditional expectation being $\infty$ still counts as existence, similar to Lebesgue integral for $[0,+\infty]$ valued functions. Also, it could be a case where expectation is infinite while its conditional is not, [1] is an example. Grimmett text, referenced there, derives conditional expectation without finite assumption for continuous r.v.s but not using measure theory. [1]: math.stackexchange.com/questions/725323/… – RozaTh Sep 12 '18 at 4:18
• @MikeEarnest Would you please explain how we can show it is $\sigma-$finite for a generic probability space and $X$? I guess we can use $X_n$ as suggested in the first comment to find the finite measure sequence, right? – RozaTh Sep 12 '18 at 4:22
To prove $\mu^X$ is $\sigma$-finite, note $\Omega=\bigcup_{n\in \mathbb N}\{|X|\le n\}$, and $\mu^X(|X|\le n)\le n$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9555637240409851, "perplexity": 254.78373970528165}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-22/segments/1558232257244.16/warc/CC-MAIN-20190523123835-20190523145835-00109.warc.gz"} |
https://math.stackexchange.com/questions/2129106/bolzano-weierstrass-theorem-implies-nested-interval-property | # Bolzano--Weierstrass Theorem implies Nested Interval Property
This question is from abbott's Understanding Analysis:
Start with the Bolzano--Weierstrass Theorem and use it to construct a proof of the Nested Interval Property.
My try: Let $I_n=[a_n,b_n]$ be closed intervals such that $I_1 \supseteq I_2 \supseteq \dots$. So here $a_n$ is a (nondecreasing) bounded sequence, so it contains a convergent subsequence by hypothesis, so does $b_n$.
But here I am stuck. I have temptation to use Monotone Convergence Theorem, but that would imply that I am assuming Axiom of Completeness, or worse, Nested Interval Property itself!
• The Axiom of spremum must be taken as a starting point. – hamam_Abdallah Feb 4 '17 at 18:08
• The Bolzano-Weierstrass recursion build the intervals that you want. Construct with every choice of the Bolzano-Weierstrass the intervals. – Masacroso Feb 4 '17 at 18:10
As you noted, there is a subsequence $n_k$ such that $a_{n_k}\to a$. As $I_n$ is closed and contains almost all $a_{n_k}$, we have $a\in I_n$. As this holds for all $n$, $a\in\bigcap I_n$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.983324408531189, "perplexity": 169.54007997196314}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-45/segments/1603107910815.89/warc/CC-MAIN-20201030122851-20201030152851-00192.warc.gz"} |
https://physicscatalyst.com/Class9/ncert_solution_numbersystem_class9_1.php | # Class 9 Maths NCERT Solutions Chapter 1 Number System
In this page we have Class 9 Maths NCERT Solutions Chapter 1 Number System for Execise 1.1 . Hope you like them and do not forget to like , social share and comment at the end of the page.
Question 1
Is zero a rational number? Can you write it in the form p/q
, where p and q are integers and q not equal to 0?
Solution:
Yes. Zero is a rational number as it can be represented as 0/1 or 0/2…
Question 2
Find six rational numbers between 3 and 4.
Solution
The six rational numbers
3.1 , 3.2, 3.3, 3.4, 3.5, 3.6
Question 3
Find five rational numbers between 3/5 and 4/5
Solution:
We need to find five rational numbers
So we multiply the denominator and numerator by (5+1) both the numbers
3/5= 18/30
4/5=24/30
So rational numbers will be in increasing order
19/30
20/30
21/30
22/30
23/30
Question 4
State whether the following statements are true or false. Give reasons for your answers.
(i) Every natural number is a whole number.
(ii) Every integer is a whole number.
(iii) Every rational number is a whole number
Solution:
(i) True; since the collection of whole numbers contains all natural numbers.
(ii) False; as integers may be negative but whole numbers are positive. For example: −3 is an integer but not a whole number.
(iii) False; as rational numbers may be fractional but whole numbers may not be
• Notes
• NCERT Solutions
• Assignments
• Revision sheet
Latest Articles
Synthetic Fibres and Plastics Class 8 Practice questions
Class 8 science chapter 5 extra questions and Answers
Mass Calculator
3 Fraction calculator
Garbage in Garbage out Extra Questions7 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8139020800590515, "perplexity": 2282.179277713704}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652663035797.93/warc/CC-MAIN-20220529011010-20220529041010-00141.warc.gz"} |
https://engtech.spbstu.ru/en/article/2012.78.22/ | # Unification of profiling tools flow forming
Authors:
Abstract:
The algorithm, which allows for all forms of description of the initial profile of gear parts to calculate the coordinates of points, angles of inclination of the tangent and normal vectors in a uniform manner, which greatly simplifies the profiling of flow forming tools. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8029760718345642, "perplexity": 660.4065946531086}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-39/segments/1631780057417.92/warc/CC-MAIN-20210923074537-20210923104537-00041.warc.gz"} |
http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articleid=2582845 | 0
Research Papers: Heat and Mass Transfer
# Continuum and Kinetic Simulations of Heat Transfer Trough Rarefied Gas in Annular and Planar Geometries in the Slip Regime
[+] Author and Article Information
Mechanical Engineering Department,
Reno, NV 89557
Dilesh Maharjan
Mechanical Engineering Department,
Reno, NV 89557
e-mail: dileshz@gmail.com
Minh-Tuan Ho
Department of Mechanical and
Aerospace Engineering,
University of Strathclyde,
Glasgow G1 1XJ 5, UK
e-mail: minh-tuan.ho@strath.ac.uk
Stefan K. Stefanov
Professor
Institute of Mechanics,
Sofia 1113, Bulgaria
e-mail: stefanov@imbm.bas.bg
Irina Graur
Aix Marseille Université,
CNRS, IUSTI UMR 7343,
13453, Marseille, France
e-mail: irina.martin@univ-amu.fr
Miles Greiner
Professor,
Fellow ASME
Mechanical Engineering Department,
Reno, NV 89557
e-mail: greiner@unr.edu
1Corresponding author.
Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received April 12, 2016; final manuscript received November 3, 2016; published online January 10, 2017. Assoc. Editor: George S. Dulikravich.
J. Heat Transfer 139(4), 042002 (Jan 10, 2017) (8 pages) Paper No: HT-16-1193; doi: 10.1115/1.4035172 History: Received April 12, 2016; Revised November 03, 2016
## Abstract
Steady-state heat transfer through a rarefied gas confined between parallel plates or coaxial cylinders, whose surfaces are maintained at different temperatures, is investigated using the nonlinear Shakhov (S) model kinetic equation and Direct Simulation Monte Carlo (DSMC) technique in the slip regime. The profiles of heat flux and temperature are reported for different values of gas rarefaction parameter δ, ratios of hotter to cooler surface temperatures $T$, and inner to outer radii ratio $R$. The results of S-model kinetic equation and DSMC technique are compared to the numerical and analytical solutions of the Fourier equation subjected to the Lin and Willis temperature-jump boundary condition. The analytical expressions are derived for temperature and heat flux for both geometries with hotter and colder surfaces having different values of the thermal accommodation coefficient. The results of the comparison between the kinetic and continuum approaches showed that the Lin and Willis temperature-jump model accurately predicts heat flux and temperature profiles for small temperature ratio $T=1.1$ and large radius ratios $R≥0.5$; however, for large temperature ratio, a pronounced disagreement is observed.
<>
## Figures
Fig. 1
Cross section of (a) two coaxial cylinders and (b) two parallel plates configurations: dimensions (r, θ) in physical space; dimensions (υr, υθ) (or(υp,φ)) in molecular velocity space
Fig. 2
Dimensionless temperature profiles between plates and cylinders for all combination of R and T and different values of rarefaction parameters δ = 100, 50, 10, and 3 in case α = 1
Fig. 3
Dimensionless heat flux as function of the rarefaction parameter δ obtained for all combination of R and T and different values of thermal accommodation coefficient α
Fig. 4
Dimensionless pressure profiles between plates and cylinders for all combination of R and T and different values of rarefaction parameters δ = 100, 50, 10, and 3 in case α = 1. l = r for R=0.5 and l = 1 − R1 + r for R=1 and 0.1.
Fig. 5
Percent deference of the dimensionless heat flux q between S-model and DSMC, and Numerical-continuum models as function of the rarefaction parameter δ obtained for all combinations of T and R and different values of thermal accommodation coefficient α
## Discussions
Some tools below are only available to our subscribers or users with an online account.
### Related Content
Customize your page view by dragging and repositioning the boxes below.
Related Journal Articles
Related Proceedings Articles
Related eBook Content
Topic Collections | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 4, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.48649778962135315, "perplexity": 3586.5206296013516}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-22/segments/1495463607871.54/warc/CC-MAIN-20170524230905-20170525010905-00238.warc.gz"} |
https://chemistry.stackexchange.com/questions/107782/ionic-compound-having-highest-solubility-in-water/107789 | # Ionic compound having highest solubility in water
Which ionic compound has highest solubility in water? I can find CsBr having highest solubility with 1230 g/L at 25 °C.
Note: compounds like ethanol are soluble to any extent in water, but they are covalent, not ionic.
• It would be interesting to split in the two cases of molar solubility and mass solubility, though the latter is easier to find data on directly. – Nicolau Saker Neto Jan 11 '19 at 2:51
• I could be cheeky and add Ionic Liquids to the list, which often mix with water at any ratio. Maybe clarify that you are talking about solids at standard conditions. – TAR86 Jan 11 '19 at 10:06
• @TAR86 Darn, I was just a bit late with my edit! I'll leave that sidenote in my answer anyway. – Nicolau Saker Neto Jan 11 '19 at 10:13
Caesium salts are unapologetically ionic, and they typically have quite high mass solubilities in many solvents, including water.
Assuming organic ions are allowed, caesium acetate ($$\ce{H3CCO2^-Cs+}$$) in particular has a remarkably high solubility of 9451 g/kg water at −2.5 °C, increasing to 13 455 g/L water at 88.5 °C.
Caesium formate ($$\ce{HCO2^-Cs+}$$) is also quite soluble, with a solubility of 4880 g/kg water at 20 °C, resulting in 2.56 L of solution with a density of 2.297 g/mL (reference, .docx file). However, its solubility increases much faster with increasing temperature (J. Chem. Soc., Trans., 1922, 121, 1837-1843). At 100 °C, it reaches an outstanding value of 20 071 g/kg water! That's 11.6 molal, or roughly 20-25 mol/L assuming the density doesn't change too much. This saturated solution is 67.7% cesium formate by number of moles, which means more than two caesium ions and two formate ions per molecule of water.
I believe I have read somewhere that caesium formate is the record holder for highest mass solubility in water (evidently only at high temperatures). If this is not true, then I can scarcely believe it will be topped by much.
Tangentially, Ivan mentions Clerici's solution, which is actually a mixture of thallium(I) formate and thallium(I) malonate. The mixture doesn't count (though the individual components are quite soluble themselves), but it interesting to analyse. Apparently 300 g of each compound will dissolve in 40 g of water without saturating it room temperature (ref), giving a lower bound to their combined solubility of 15 000 g/kg water. This value rises with heating, and is the only way I can see to beat the mass solubility of caesium formate.
For further entertainment, I recommend these two solubility tables with a large number of entries (1, 2). The second one can be ordered by solubility at different temperatures. It's interesting to see the variety of cations and anions which can be combined to display extreme mass solubility.
Edit: If room-temperature ionic liquids are allowed, then it is quite likely some of them are miscible with water in any proportion, which is effectively "infinite solubility in water". Something as simple as ethylammonium nitrate ($$\ce{C2H5NH3+NO3-}$$) may suffice.
• If they are ionic, the state of matter does not matter. +1. – Oscar Lanzi Jan 11 '19 at 12:10
The following data is compiled from [1, pp. 4-44, 5-167]:
Table 1. Selected solubility values of the inorganic compounds with significant ionic character at $$25~\mathrm{^\circ C}$$. $$\begin{array}{lc} \hline \text{Formula} & \text{Solubility in water}/\pu{g L-1}\\ \hline \ce{CsF} & 5730\\ \ce{SbF3} & 4920\\ \ce{LiClO3} & 4587\\ \ce{Pb(ClO4)2} & 4405\\ \ce{ZnCl2} & 4080\\ \hline \end{array}$$
Solubility of antimony(III) trichloride $$\ce{SbCl3}$$ is $$9870~\mathrm{g~L^{-1}}$$ at $$25~\mathrm{^\circ C}$$, but technically it's not an ionic compound.
### References
1. Haynes, W. M.; Lide, D. R.; Bruno, T. J. CRC Handbook of Chemistry and Physics: A Ready-Reference Book of Chemical and Physical Data.; 2017; Vol. 97.
• I've seen antimony trichloride before in tables, but it is apparently very easily hydrolysed, so perhaps it shouldn't be counted either way. – Nicolau Saker Neto Jan 11 '19 at 7:53
• @NicolauSakerNeto Yep, you are right, and the same probably goes for $\ce{ZnCl2}$. I also omitted $\ce{ZnBr2}$ for similar reason (and it's covalency, too). – andselisk Jan 11 '19 at 7:55
There is not going to be a single definitive answer, primarily because of a wide gray zone surrounding the domain of ionic compounds. Besides, as Nikolau noted, the question is ambiguous.
If you want mass concentration, then look at $$\ce{InI3}$$ which claims a whopping $$13100~\mathrm{g/L}$$. Pity that it is probably ionic in name only, judging by the solubility in non-polar solvents. Well, then look at those mentioned by andselisk, though the ionic nature of some of them is also debatable, and then at the thallium formate (a component of Clerici solution) with $$\sim5000~\mathrm{g/L}$$.
If you want molar concentration, then the question is still ambiguous (are we looking at molarity or molality?), and the pretty strong contenders are $$\ce{NaOH}$$, $$\ce{BeF2}$$, $$\ce{LiClO3}$$.
So it goes.
• True, $\ce{InI3}$ is weird, but it's definitely not ionic and the reference for the solubility value dates back to 1940s or something:) – andselisk Jan 11 '19 at 6:54
We can do better than that. Ammonium nitrate = 1500 g/L at 20°C. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 14, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6816633343696594, "perplexity": 2775.6721643225296}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141182794.28/warc/CC-MAIN-20201125125427-20201125155427-00532.warc.gz"} |
https://docs.google.com/forms/d/e/1FAIpQLSfQGh6OTTkTMFQ4JWcyhamj84pC5my7fEQWNnWMIqyzd97A2A/viewform?usp=send_form | Asa's Angels: GOLF OUTING *Golfer* Registration
Please Register for the Event Below!!
Upon Your Successful Registration, A Confirmation Email will be Sent to You!!
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EVENT DETAILS:
*When: Sunday July 24th, 2022
*Where: Powderhorn Golf Course
*Tickets: \$100/player (\$400 per foursome)
*Time: Shotgun Starts @ 11 am
***Registration Begins at 9:30a
*Dinner at Powderhorn, immediately following provided by Jones Bones Food Truck.
*Lunch at the turn, provided by Powderhorn
*50/50 .. and Raffle Prizes called during Dinner!
*Cash and Credit Cards are Accepted during Event
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
After Your Golfer Registration > FOR PAYMENT,
Please Pay for Your Ticket Online at Either:
https://account.venmo.com/u/Asa-Cox-5
https://cash.app/\$asasangels
** Or if You Do Not Have CASH APP or VENMO:
Please call Cassandra @ 440.221.9344 for Credit Card Payment over the Phone
When Completing your Payment via CashApp or Venmo: Please be sure to put the Name of Which You Just Registered in the "Memo" Line for our Tracking Purposes!
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Questions?
THANK YOU SO MUCH FOR YOUR SUPPORT!!
Email *
Name of Person Registering *
Phone Number of Person Registering *
Email Address of Person Registering *
Are you Registering & Paying for More than Just Yourself? *
Next
Clear form | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9357814788818359, "perplexity": 95.08205322809603}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656103036099.6/warc/CC-MAIN-20220625190306-20220625220306-00789.warc.gz"} |
https://www.physicsforums.com/threads/simple-time-independent-perturbation-problem-qm.272106/ | # Simple time-independent perturbation problem. QM
1. Nov 15, 2008
### armis
1. The problem statement, all variables and given/known data
"Suppose we put a delta-function in the center of the infinite square well:
$${H^{'}} = \alpha\delta(x-a/2)$$ where a is a constant. Find the first order correction to the allowed energies. Explain why the energies are not peturbed for even n"
2. Relevant equations
3. The attempt at a solution
Just to make sure. The energies for even n are not peturbed because the wave functions are odd with respect to the center of the well, thus equal to zero at those points where the delta-function potential is (if our square well is from 0 to a). Is that correct?
2. Nov 15, 2008
### Avodyne
Yes, that's correct!
3. Nov 16, 2008
thanks | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9678123593330383, "perplexity": 939.1866397017247}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257651007.67/warc/CC-MAIN-20180324210433-20180324230433-00127.warc.gz"} |
https://www.groundai.com/project/characteristics-of-transverse-waves-in-chromospheric-mottles/ | Characteristics of transverse waves in chromospheric mottles
# Characteristics of transverse waves in chromospheric mottles
## Abstract
Using data obtained by the high temporal and spatial resolution Rapid Oscillations in the Solar Atmosphere (ROSA) instrument on the Dunn Solar Telescope, we investigate at an unprecedented level of detail transverse oscillations in chromospheric fine structures near the solar disk center. The oscillations are interpreted in terms of propagating and standing magnetohydrodynamic kink waves. Wave characteristics including the maximum transverse velocity amplitude and the phase speed are measured as a function of distance along the structure’s length. Solar magneto-seismology is applied to these measured parameters to obtain diagnostic information on key plasma parameters (e.g., magnetic field, density, temperature, flow speed) of these localised waveguides. The magnetic field strength of the mottle along the 2 Mm length is found to decrease by a factor of 12, while the local plasma density scale height is 28080 km.
Waves — magnetohydrodynamics (MHD) — Magnetic fields — Sun: Atmosphere — Sun: chromosphere — Sun: oscillations
## 1. Introduction
Chromospheric fine-scale structures such as limb spicules, on-disk mottles and dynamic fibrils are among the most popular objects for study in solar physics today. These jet-like plasma features, formed near the network boundaries, can protrude into the transition region and low corona (Beckers, 1968, 1972; Sterling, 2000; De Pontieu & Erdélyi, 2006) and act as conduits for channeling energy and mass from the solar photosphere into the upper solar atmosphere and the solar wind (De Pontieu et al., 2004; De Pontieu & Erdélyi, 2006; Morton et al., 2012a).
Recent ground-based and space-borne observations have shown a plethora of waves and oscillations in these structures (Kukhianidze et al., 2006; Zaqarashvili et al, 2007; De Pontieu et al., 2007; He et al., 2009a, b; Zaqarashvili & Erdélyi, 2009; Okamoto & de Pontieu, 2011; Kuridze et al., 2012; Morton et al., 2012b; Mathioudakis et al., 2013). These oscillations are usually observed as periodic transverse displacements (Zaqarashvili & Erdélyi, 2009; Okamoto & de Pontieu, 2011; Pietarila et al., 2011; Kuridze et al., 2012; Morton et al., 2012b). The observations support the idea that the chromospheric fine-structures can be modelled as thin, overdense magnetic flux tubes that are waveguides for the transverse oscillations with periods which have an observational upper bound limited by their finite visible lifetime. This is also supported by 3-D numerical modelling of the chromosphere (Leenaarts et al., 2012). In this regard, the observed transverse oscillations have been interpreted as fast kink MHD waves (Spruit, 1982; Erdélyi & Fedun, 2007).
Despite a number of recent advances in the field, a detailed study of the properties and physical nature of the chromospheric fine-structures remains a challenging observational task. The propagating or standing nature of the oscillations are crucial in understanding the role of these waves in the energy balance of the solar atmosphere and their contribution to the atmospheric heating process. Both propagating (upward and downward) and standing transverse oscillations have been reported in limb spicules (Zaqarashvili et al, 2007; Zaqarashvili & Erdélyi, 2009; He et al., 2009a, b; Okamoto & de Pontieu, 2011). In addition, a few instances of propagating oscillations were recorded as well in chromospheric mottles (Kuridze et al., 2012; Morton et al., 2012b), that are believed to be the disk counterparts of limb spicules (Tsiropoula & Schmieder, 1997; Zachariadis et al., 2001; Hansteen et al., 2006; Scullion et al., 2009; Rouppe van der Voort et al., 2009).
The study of MHD wave properties in spicular structures opens new dimension to chromospheric plasma diagnostics using the tools of solar magnetoseismology (SMS), a field that has recently emerged (for reviews on SMS see e.g., Erdélyi, 2006; Andries et al., 2009; Ruderman & Erdélyi, 2009; Taroyan & Erdélyi, 2009). One of the techniques developed estimates the variation of magnetic field strength and plasma density along the chromospheric magnetic flux tube from the properties of kink waves (Verth et al., 2011). This approach has been successfully applied to Hinode/SOT Ca ii H limb spicule observations (Verth et al., 2011).
In this paper, we present results on transverse oscillations observed in the H on-disk and quiet-solar chromospheric mottles. Our works provide evidence for upward and downward propagating and standing waves. In the case of propagating sample wave characteristics such as maximum transverse velocity amplitude and phase speed are measured as a function of distance along the structures length. The wave properties are used to estimate plasma parameters along the waveguide by employing the SMS approach.
## 2. Observations and data reduction
Observations were undertaken between 13:46 - 14:40 UT on 28 May 2009 at disk centre with the Rapid Oscillations in the Solar Atmosphere (ROSA; Jess et al., 2010a) imaging system, and with the Interferometric Bidimensional Spectrometer (IBIS; Cavalini, 2006), mounted at the Dunn Solar Telescope (DST) at the National Solar Observatory, New Mexico, USA. The ROSA dataset includes simultaneous imaging in the H core at 6562.8 Å (bandpass 0.25 Å), Ca II K core at 3933.7 Å (bandpass 1.0 Å), G band at 4305.5 Å, bandpass (9.20 Å), and line-of-sight (LOS) magnetograms. High-order adaptive optics were applied throughout the observations (Rimmele, 2004). The images were reconstructed by implementing the speckle algorithms of Wöger et al. (2008) followed by de-stretching. These algorithms have removed the effects of atmospheric distortion from the data. The effective cadence after reconstruction is reduced to 4.2243 s for H and Ca ii K. Observations were obtained with a spatial sampling of /pixel corresponding to a spatial resolution of over the field-of-view (FOV).
LOS magnetograms were constructed using the left- and right-hand circularly polarised light obtained 125 mÅ into the blue wing of the magnetically-sensitive Fe i line at 6302.5 Å. A blue-wing offset was required to minimise granulation contrast, while conversion of the filtergram into units of Gauss was performed using simultaneous SOHO/MDI magnetograms (see discussion in Jess et al. 2010b).
IBIS undertook simultaneous Na i D core imaging at 5895.94 Å with a spatial sampling of /pixel over the same FOV. The IBIS data have a post-reconstruction cadence of 39.7 s. Despite difficulties in interpreting the Na i D line formation height, it is suggested that it is formed in the upper photosphere/lower chromosphere (Eibe et al., 2001; Finsterle et al., 2004). Doppler wavelength shifts of the Na i D line profile minimum were used to construct LOS velocity maps of the same FOV (for more details, see Jess et al., 2010b).
## 3. Results and analysis
Figure 1 shows co-spatial and co-temporal snapshots in the H core and in Ca ii K, and G band, where the FOV covers a quiet Sun region near disk centre. The H image contains a large rosette structure located near the centre (see the top left panel of Figure 1). Rosettes are clusters of elongated, dark H mottles expanding radially around a common centre over internetwork regions (Zachariadis et al., 2001; Tziotziou et al., 2003; Rouppe van der Voort et al., 2007). An additional three smaller rosettes are visible in the lower left of the boxed area (the top left panel of Figure 1). The roots of the rosettes are co-spatial with Ca ii K brightenings, G band bright points and strong magnetic field concentrations which outline the boundaries of supergranular cell highlighted with the dashed box in Figure 1. A LOS magnetogram of the FOV shows that the supergranular cell boundary consist of opposite polarity magnetic field concentrations (bottom right panel of Figure 1).
The application of time-distance analysis to the H images reveals that the mottles display transverse motions perpendicular to their axis, usually interpreted as transverse MHD kink motions (Spruit, 1982; Edwin & Roberts, 1983; Erdélyi & Fedun, 2007). Periodic transverse displacements of three different mottles, marked with crosses in Figure 1, have been selected for further analysis.
Figure 2 shows a more detailed view of the mottle located near the red cross in Figure 1. The projected length of the structure is 4 Mm, with a resolved average width of 350 km and lifetime of 3 min. Red lines across the structure indicate the locations of the cross-cuts used to study the transverse oscillations. We use the cross-cuts to generate two-dimensional time-distance (t-d) diagrams that reveal the transverse motions at each point along the mottle’s length. These t-d samples are plotted in the middle panel of Figure 2. The shift detected in the signal, as a function of time, indicates that the observed oscillation is due to a propagating wave. Displacements are determined by fitting a Gaussian function to the cross-sectional flux profile for each time frame of the transverse cross-cuts (right panel of Figure 2). This method can determine the position of the structure’s centroid to within one pixel and thus has an error of 50 km. It should be noted that in Figure 2 there are only eight cross-cuts (separated by 0.5 Mm), the corresponding time-distance diagrams and time series, respectively. We note that we generated and analysed the t-d diagrams for 15 cross-cuts separated by 0.25 Mm but we chose to show here only 8 of those for presentation purposes. A linear trend was subtracted from the displacement time-series to obtain the periodic motions. The time series was fitted with a harmonic function at each position along the mottle from which the periods of the wave are derived with a median value of .
We measured the maximum transverse displacements at each of the 15 positions along the mottle length (left panel of Figure 2). The maximum transverse velocity amplitudes are derived using , where and are the maximum transverse displacement and period of the oscillation, respectively. Uncertainties in are estimated from the error in and the standard deviation of . The results with the associated error of each data point are plotted in the left panel of Figure 3. This figure clearly shows that the velocity amplitude is increasing up to around (Figure 3) and then decreases. Due to the different trends the first 8 and last 7 data points are fitted separately by an exponential function of the form , where is the distance along the mottle. We note that the exponential function has the best-fit (with 95 confidence level) for the first 8 datapoints. We obtain and for and for . Errors in these fitting parameters are their 1 uncertainties derived from the fitting algorithm, which use the measurement error for each data point.
The phase speed of the transverse motions can be evaluated from the time-delay in the signals obtained at different positions along the mottle. From the displacement time series we can measure the time coordinates of the maximum transverse displacements. A phase speed between two positions along the structure can be calculated as , where is the distance between two selected heights and is the time delay between the location of the maximum displacements. The time at the location of the maximum transverse displacement in the time series can be estimated within one temporal resolution element of 4.224 s, and the maximum phase speed which can be resolved for the length along the structure is . We determine a reliable phase speed of the transverse wave for six consecutive segments along the mottle length and results (with corresponding measurement errors) are plotted in the right panel of Figure 3. The phase speed is near the lower part of the mottle and increases to at 2.5 Mm, then it decreases again towards the end of the structure (right panel of Figure 3). We fit the data points using an exponential function of the form with , for and for .
Figure 4 shows the H mottle (left panel) located near the green cross of Figure 1 and its transverse displacements at different positions along its length (middle and right panels of Figure 4). Time series, obtained using a similar method to that described for the first mottle in Figure 2, highlight the upward and downward propagating waves with a period of (see the green and blue diagonal lines in the right panel of Figure 4). The average phase speed and maximum transverse velocity along the length of the mottle are , , , and for the upward and downward propagating waves, respectively. Unfortunately, for this example large uncertainties in the transverse velocity and phase speed measurements do not allow us to study their variation as a function of distance.
Figure 5 shows the chromospheric structure marked with a blue cross in Figure 1 and its transverse displacement with a period of . We detect a marginal delay, of about 10 s, in the oscillation signals at the lower and upper positions (Figure 5). This time delay, combined with a distance of around 3.5 Mm between these positions (see left panel of Figure 4), gives a propagating speed of more than 350 km/s, too high a value for what might be expected for the phase speed of the kink waves in chromospheric mottles. We believe that this high speed may be caused by the standing wave pattern generated by the superposition of two oppositely directed waves.
## 4. Magnetoseismological diagnostics
A novel solar magnetoseimology tool that allows us to determine the variation of magnetic field and plasma density along a chromospheric structure using the characteristics of kink oscillations has been developed by Verth et al. (2011). Based on their approach, if the kink speed , (which is the phase speed of the kink wave) and maximum transverse velocity amplitude are estimated from observations, the expansion rate of the magnetic flux tubes can be derived from the solution of the kink wave governing equation (see Equation 1 of Verth at al. 2011). The flux tube radius as a function of is given by
R(s)=R(0)exp(sH) , (1)
where and , are fitting parameters defined from the measured and , and is the flux tube radius at the lowest position (Verth et al., 2011). On the other hand, from magnetic flux conservation , where is the average magnetic field strength, and the variation of magnetic field along the flux tube can be estimated. Furthermore, from the kink speed and magnetic field variations, the plasma density along the structure can also be determined using
ρ(s)∝B2(s)v2ph(s), (2)
where is the average of the internal and external plasma densities (see Verth et al. 2011 for further details).
Inspired by this work, we estimate these parameters for the on-disk mottle presented on Figure 2 using the same SMS tool. We employ the functions of and found in the previous section using the exponential fit for the measured phase travel time and velocity amplitudes. From these functions, which define and , and from Equation (1) we make piecewise estimate the normalised area expansion of the flux tube. The magnetic field variation can also be evaluated from the area expansion and magnetic flux conservation law (middle panel of Figure 6). Furthermore, the normalised plasma density along this mottle, estimated from Equation (2), is shown in the right panel of Figure 6.
## 5. Discussion and conclusions
Several observational and theoretical studies suggest that the transverse MHD kink waves observed in chromospheric structures can be excited by granular buffeting, global oscillations, mode conversion or torsional motions in the photospheric bright points where chromospheric fine structures are anchored (Roberts, 1979; Spruit, 1981; Hollweg, 1981; Hasan & Kalkofen, 1999; De Pontieu et al., 2004; Jess et al., 2012; Morton et al., 2013). By tracking the oscillation signals at different positions, we detected both propagating and standing wave modes along chromospheric mottles which appear to be rooted in regions with strong magnetic field concentrations (Figure 1). Upward propagating waves with periods of are detected in one of the mottles (Figure 2). The analysis shows that the phase speed and transverse velocity amplitude rise exponentially with distance along the mottle length up to about before they begin to decrease (Figure 3). MHD wave theory suggests that the variation of these wave characteristics are controlled by changes in plasma parameters such as density and magnetic field strength along the waveguide. A decrease in the plasma- will result in the mottle plasma parameters gradually becoming dominated by the magnetic field, causing the observed growth of the phase speed (Figure 3). At a height of around , the magnetic canopy is formed (Solanki & Steiner, 1990; Wedemeyer-Böhm et al., 2009; Tsiropoula et al., 2012). This is the layer where the gas and magnetic pressures are equal () and where the mode conversion through e.g. non-linear interactions can occur (Rosenthal et al., 2002; Bogdan et al., 2003; Hasan et al., 2003; Schunker & Cally, 2006; Kuridze et al., 2008). The amplitude of the transverse motions increases and at about reaches (Figure 2), a value similar to the waveguide width of 350 km. Hence, the observed fast kink wave mode may become nonlinear near the canopy area, which may lead to mode conversion, and thus energy transfer between nonlinear kink modes and longitudinal waves. This can result in the observed decrease of phase speed and transverse velocity at a higher length along the structure (Figure 3).
Waves that propagate from the lower chromosphere into the transition region may undergo reflection at the top of the canopy due to the sharp density gradient (Hollweg et al., 1982; Rosenthal et al., 2002; Kuridze et al., 2008; Fujimura & Tsuneta, 2009). The conditions for the reflection of the kink waves are defined by the local cut-off period, the highest period that is allowed to propagate. Following the Kneser oscillation theorem (Kneser, 1893), if the phase speed is increasing with height, the governing kink wave equation processes a cut-off which can be calculated as , where is the change of the phase speed as a function of distance , and is the distance between two selected points. For the waveguide presented in Figure 2 this corresponds to a cut-off period of . This value is much higher than the observed kink wave period () suggesting that the observed wave, and waves with periods less then the estimated cut-off, should propagate into the upper chromospheric layers without reflection. The high cut-off period indicates that the chromospheric mottles could allow the propagation of long period () transversal (kink and Alfvén) waves as well. Those waves are observed in the corona and are thought to be an important contributor to the coronal heating, at least in the case of the quiet Sun (e.g., McIntosh et al., 2012).
It appears that the upward and downward directed waves (green and blue diagonal lines in the right panel of Figure 4) have an approximately constant phase speed () along the mottle length. Almost constant phase speeds for torsional waves were also detected along limb spicules (see e.g., De Pontieu et al., 2012; Sekse et al., 2013). A constant phase speed suggests that there is no cut-off period, i.e. waves of any period can propagate along those fine-scale structures in the chromosphere. However, the downward propagating wave detected along the mottle presented in Figure 4 may be formed as a result of reflection of the upward propagating wave at the transition region boundary or in the corona. Furthermore, for this mottle we measured and , where and are the phase speeds of upward and downward propagating waves, respectively. This difference could be a result of plasma flow along the mottle. In the presence of flow the upward and downward kink speeds are modified by the flow as follows,
vup=vph+U, (3)
vdown=vph−U, (4)
where, is the kink speed for the mottle with no flow, and is the flow speed. This suggests a plasma flow along this mottle of in the upward direction. A snapshot of the LOS velocity map of the studied region, obtained from Doppler wavelength shifts of the profile, shows that the lower chromosphere is dominated by the flow patterns (Figure 7). Values of the flow speed vary from around (upward) to (downward) with an error of (Jess et al. 2010b). The average upflow LOS velocity near the footpoint of this mottle is around (Figure 7). This value is consistent with the seismologically estimated phase speed, , which is the horizontal component and thus may be higher depending on the structure’s inclination. Recently, Vissers & Rouppe van der Voort (2012) measured upflow/downflow velocities within the range of in chromospheric fibrils, consistent with our observations and SMS estimations.
A superposition of the opposite directed kink waves may result into a wave with a very high phase speed which can be considered as a (partially) standing wave (Fujimura & Tsuneta, 2009). The phase speed of the transverse wave shown in Figure 5 is . This value is considerably higher than the local Alfvén/sound/kink speeds, indicating that it may be the consequence of the superposition of up and down propagating waves.
In Figure 6 we show the normalised estimated area expansion, magnetic field and plasma density variations as function of length along the waveguide shown in Figure 2. The area expansion factor along the flux tube length is found to be (left panel of Figure 6), with a decrease in the magnetic field strength of the same factor (middle panel of Figure 6). Unfortunately, even modern high-resolution observations can not yet provide direct, precise measurements of the flux tube expansion rate and magnetic field variation from the photosphere to chromosphere. Thus, it is very difficult to compare the results obtained from magnetoseismological techniques with direct measurements. We emphasize that spectropolarimetric measurement of chromospheric spicular magnetic field strengths of (Trujillo Bueno et al., 2005; Centeno et al., 2010), and the observed footpoint photospheric magnetic field strength of (lower right panel of Figure 1) give comparable factors for the decrease in the field strength.
It must be noted that the H image of the mottle (left panel of Figure 6) does not show visual expansion by a factor of 12 (that would correspond to a radius change by a factor of 3.5). Gaussian fit to the cross-sectional flux profile of the mottle suggests that the width of this structure at around 2 Mm at its length (left panel of Figure 6) is 350 km. Hence, according to our SMS estimation the width at its base is expected to be 100 km. This is the typical diameter of the G-band bright points which are considered as the footpoints of the mottles (Crockett et al., 2010). However, 100 km is below the spatial resolution of the ROSA H filter. DeForest (2007) has suggested that the solar threadlike structures’ expansion may not be seen visually (through imaging observations) if the threads have sub-resolution width. The chromospheric fine structures analysed in this paper are near the resolution limit which could be the reason of the relatively constant apparent width along their length.
The normalised plasma density from our magnetoseismological study (plotted in the right panel of Figure 6) shows that the density along the mottle decreases by in a 2 Mm length. Despite such significant drop in density, the mottle is still visible in the H images. For a resolved dense flux tube in the chromosphere, the intensity is proportional to density, opacity, geometric depth and the source function. The source function gives the contribution that the plasma makes to the intensity due to absorption/emission and cannot be determined directly from observation. With respect to unresolved (or near resolution) flux tubes there are added complications. DeForest (2007) investigated the effect of geometric expansion on intensity for such structures. He found that the effect of sub-resolution flux tube expansion results in an apparent constant flux tube width and enhanced brightness with height (see Fig. 4 of DeForest 2007) .This simple geometric effect could be true for the dark, absorption H mottles as well, and hence it may be the explanation to why the upper part of the mottle is visible in H. In addition, we would like to emphasise that the density of H dark mottles estimated by previous work (see e.g. Tsiropoula & Schmieder 1997) is about cm. For this value, our SMS density diagnostic method suggests that near the base the density would be approximately cm, which is a realistic value according to different atmospheric models (see e. g., Vernazza et al., 1981; Fontenla et al., 2007).
Density diagnostics provide an estimate for the local plasma density scale height of along the length, lower than some previous seismological estimates of the scale height () in limb spicules (Verth et al., 2011; Makita, 2003). The density scale height could be used to estimate the mottle temperature in the isothermal approximation using (see, e.g., Aschwanden, 2004). This yields for the mottles presented in Figure 4. The earlier work of Giovanelli (1967) estimates the temperatures of the dark mottles to be . Based on some parameters given by the cloud model Tsiropoula et al. (1993) derived values in the range 7100-13000 K. Later on, Tsiropoula & Schmieder (1997) claimed that dark mottles for the microturbulent velocity around have with standard deviation (see Table 1 of Tsiropoula & Schmieder 1997). The SMS temperature diagnostic suggests that the particular dark mottle analysed here is at the lower end of previous temperature range estimates. Providing new insight, SMS suggests the dark mottle is reasonably isothermal along its structure, at least up to 2 Mm from its footpoint. However, more SMS dark mottle case studies will be required to actually understand how representative the present example is.
The application of SMS diagnostics to the mottle for lengths greater than 2 Mm, show a decrease in the plasma density and magnetic field gradients. Although these features were also found for an off-limb spicule (Verth et al., 2011), we point out that our estimates above 2 Mm carry large uncertainties. The observed changes could be caused by the effects of the magnetic canopy. The merging flux tubes higher in the atmosphere could alter the rate at which the magnetic field decreases. At the canopy level the flux tubes become more horizontal which can change the density stratification along the structure. We note that the SMS estimates presented here are more applicable to the local plasma parameters of a particular small-scale flux tube, and they may not necessarily be considered as typical of all chromospheric structures. However, it has been demonstrated that by studying the variation of phase speed and transverse velocity of kink waves along mottles and fibrils we can understand more completely the dominant plasma properties of chromospheric waveguides. Furthermore, a wealth of statistics for phase speed variations can provide typical values for the cut-off period. Transverse oscillations which are ubiquitous in the chromosphere (Kuridze et al., 2012; Morton et al., 2012b) are likely to be separated in propagating and non-propagating waves by the cut-off period. Hence, it could be crucial to estimate how much kink wave energy is transported into the corona and what is trapped in the chromosphere.
This work is supported by the UK Science and Technology Facilities Council (STFC). RE acknowledges M. Kéray for patient encouragement and is also grateful to NSF Hungary (OTKA K83133). We thank the Air Force Office of Scientific Research, Air Force Material Command, USAF for sponsorship under grant number FA8655-09-13085. G.V. acknowledge the support of the Leverhulme Trust.
### References
1. Aschwanden, M. J. 2004, Physics of the Solar Corona: An Introduction (Berlin: Springer)
2. Andries, J., van Doorsselaere, T., Roberts, B., et al. 2009, SSRv, 149, 3
3. Beckers, J. M. 1968, Sol. Phys., 3, 367
4. Beckers, J. M. 1972, ARA&A, 10, 73
5. Bogdan, T. J., Carlsson, M., Hansteen, V. H., et al. 2003, ApJ, 599, 626
6. Cavallini, F. 2006, Sol. Phys., 236, 415
7. Centeno, R., Trujillo Bueno, J., & Asensio Ramos, A. 2010, ApJ, 708, 1579
8. Crockett, P. J., Mathioudakis, M., Jess, D. B., et al. 2010, ApJ, 722, L188
9. DeForest, C. E. 2007, ApJ, 661, 532
10. De Pontieu, B., Erdélyi, R., & James, S. P. 2004, Nature, 430, 536
11. De Pontieu, B., & Erdélyi, , R. 2006, R. Soc. Lond. Phil. Trans. Ser. A, 364, 383
12. De Pontieu, B., McIntosh, S. W., Carlsson, M., et al. 2007, Science, 318, 1574
13. De Pontieu, B., Carlsson, M., Rouppe van der Voort, L. H. M., et al. 2012, ApJ, 752, L12
14. Eibe, M. T., Mein, P., Roudier, T., & Faurobert, M. 2001, A&A, 371, 1128
15. Edwin, P. M., & Roberts, B. 1983, Sol. Phys., 88, 179
16. Erdélyi, R., & Fedun, V. 2007, Science, 318, 1572
17. Erdélyi, R. 2006, Phil. Trans. R. Soc. A, 364, 35
18. Finsterle, W., Jefferies, S. M., Cacciani, A., Rapex, P., & McIntosh, S. W. 2004, ApJ, 613, L185
19. Fontenla, J. M., Balasubramaniam, K. S., & Harder, J. 2007, ApJ, 667, 1243
20. Fujimura, D., & Tsuneta, S. 2009, ApJ, 702, 1443
21. Giovanelli, R. G. 1967, Aust. J. Phys., 20, 81
22. He, J., Tu, C., Marsch, E., Guo, L., Yao, S., & Tian, H. 2009a, A&A, 497, 525
23. He, J., Marsch, E., Tu, C., & Tian, H. 2009b, ApJ, 705, L217
24. Hansteen, V. H., De Pontieu, B., Rouppe van der Voort, L., van Noort, M., & Carlsson, M. 2006, ApJ, 647, L73
25. Hasan, S. S., & Kalkofen, W. 1999, ApJ, 519, 899
26. Hasan, S. S., Kalkofen, W., van Ballegooijen, A. A., & Ulmschneider, P. 2003, ApJ, 585, 1138
27. Hollweg, J. V. 1981, Sol. Phys., 70, 25
28. Hollweg, J. V., Jackson, S., & Galloway, D. 1982, Sol. Phys., 75, 35
29. Jess, D. B., Mathioudakis, M., Christian, D. J., Keenan, F. P., Ryans, R. S. I., & Crockett, P. J. 2010a, Sol. Phys., 261, 363
30. Jess, D. B., Mathioudakis, M., Christian, D. J., Crockett, P. J., & Keenan, F. P. 2010b, ApJ, 719, L134
31. Jess, D. B., Pascoe, D. J., Christian, D. J., Mathioudakis, M., Keys, P. H.,& Keenan, F. P. 2012, ApJ, 744, L5
32. Kukhianidze, V., Zaqarashvili, T. V., & Khutsishvili, E. 2006, A&A, 449, L35
33. Kneser, A. 1893, MatAn, 42, 409
34. Kuridze, D., Morton, R. J., Erdélyi, R., et al. 2012, ApJ, 750, 51
35. Kuridze, D., Zaqarashvili, T. V., Shergelashvili, B. M., & Poedts, S. 2008, Ann. Geophys., 26, 2983
36. Leenaarts, J., Carlsson, M., & van der Voort, L. R. 2012, ApJ, 749, 136
37. McIntosh, S. W., de Pontieu, B., Carlsson, M., et al. 2011, Natur, 475, 477
38. Makita, M. 2003, Publ. Natl Astron. Obs. Japan, 7, 1
39. Mathioudakis, M., Jess, D. B., & Erdélyi, R. 2013, Space Sci. Rev., 175, 1-4
40. Morton, R. J. 2012a, A&A, 543, 6
41. Morton, R. J., Verth, G., Jess, D. B., et al. 2012b, NatCo, 3, 1315
42. Morton, R. J., Verth, G., Fedun, V., Shelyag, S., & Erdélyi, R. 2013, ApJ, 768, 17
43. Okamoto, Takenori J., & de Pontieu, B. ApJ, 2011, 736, L24
44. Pietarila, A., Aznar Cuadrado, R., Hirzberger, J., & Solanki, S. K. 2011, ApJ, 739, 92
45. Rae, I. C., & Roberts, B. 1982, ApJ, 256, 761
46. Rimmele, T. R. 2004, Proc. SPIE, 5490, 34
47. Roberts, B. 1979, Sol. Phys., 61, 23
48. Rosenthal, C. S., Bogdan, T. J., Carlsson, M., et al. 2002, ApJ, 564, 508
49. Rouppe van der Voort, L., De Pontieu, B., Hansteen, V., Carlsson, M., & van Noort, M. 2007, ApJ, 660, 169
50. Rouppe van der Voort, L., Leenaarts, J., de Pontieu, B., Carlsson, M., & Vissers, G. 2009, ApJ, 705, 272
51. Ruderman, M. S. & Erdélyi, R. 2009, Space Sci. Rev., 149, 199
52. Schunker, H., & Cally, P. S. 2006, MNRAS, 372, 551
53. Scullion, E., Popescu, M. D., Banerjee, D., Doyle, J. G., & Erdélyi, R. 2009, ApJ, 704, 1385
54. Sekse, D. H., Rouppe van der Voort, L., De Pontieu, B., & Scullion, E. 2013, ApJ, 769, 44
55. Solanki, S. K., & Steiner, O. 1990, A&A, 234, 519
56. Solanki, S. K. 1993, Space Sci. Rev., 63, 1
57. Spruit, H. C. 1982, SoPh, 75, 3
58. Spruit, H. C. 1981, A&A, 98, 155
59. Sterling, A. C. 2000, Sol. Phys., 2000, 196, 79
60. Taroyan, Y., & Erdélyi, R. 2009, Space Sci. Rev., 149, 229
61. Trujillo Bueno, J., Merenda, L., Centeno, R., Collados, M., & Landi DeglÕInnocenti, E. 2005, ApJ, 619, L191
62. Tziotziou, K., Tsiropoula, G., & Mein, P. 2003, A&A, 402, 361
63. Tsiropoula, G., Alissandrakis, C. E., & Schmieder, B. 1993, A&A, 271, 574
64. Tsiropoula, G., & Schmieder, B. 1997, A&A, 324, 1183
65. Tsiropoula, G., Tziotziou, K., Kontogiannis, I., et al. 2012, SSRv, 169, 181
66. Vissers, G., & Rouppe van der Voort, L. 2012, ApJ, 750, 22
67. Vernazza, J. E., Avrett, E. H., & Loeser, R. 1981, ApJS, 45, 635
68. Verth, G., Goossens, M., & He, J.-S. 2011, ApJ, 733, L15
69. Wedemeyer-Böhm, S., Lagg, A., & Nordlund, Å. 2009, SSRv, 144, 317
70. Wöger, F., von der Lühe, O., & Reardon, K. 2008, A&A, 488, 375
71. Zachariadis, Th. G., Dara, H. C., Alissandrakis, C. E., Koutchmy, S.,& Contikakis, C. 2001, Sol. Phys., 202, 41
72. Zaqarashvili, T. V., Khutsishvili, E., Kukhianidze, V., & Ramishvili, G. 2007, A&A, 474, 627
73. Zaqarashvili, T. V., & Erdélyi, R. 2009, Space Sci. Rev., 149, 355
You are adding the first comment!
How to quickly get a good reply:
• Give credit where it’s due by listing out the positive aspects of a paper before getting into which changes should be made.
• Be specific in your critique, and provide supporting evidence with appropriate references to substantiate general statements.
• Your comment should inspire ideas to flow and help the author improves the paper.
The better we are at sharing our knowledge with each other, the faster we move forward.
The feedback must be of minumum 40 characters | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9334765076637268, "perplexity": 2846.3832882648294}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202525.25/warc/CC-MAIN-20190321132523-20190321154523-00256.warc.gz"} |
https://stats.stackexchange.com/questions/327847/mle-for-the-conditional-logit-model-seems-to-have-awful-precision | # MLE for the conditional logit model seems to have awful precision?
I'm simulating the data underlying a conditional logit model then doing my own MLE estimation using optim. However, even with an unreasonably large amount of data, the estimator seems to have awful precision. Is this expected, or I am making mistakes in my implementation?
Conditional Logit Model: The conditional logit is a discrete choice model, where a person chooses between multiple alternatives based on the alternatives' covariates. We want to estimate the person's preference for these covariates.
The person chooses the alternative that gives him the highest utility. For example, with 3 choices, the 3 utility functions are:
$$U_{i1} = \alpha' X_1 + \varepsilon_1 \\ U_{i2} = \alpha' X_2 + \varepsilon_2 \\ U_{i3} = \alpha' X_3 + \varepsilon_3$$
where $$\alpha$$ is the preference parameters to be estimated, and $$X$$ is the alternative's covariates that we observe.
In the conditional logit model, we assume that the random utility components (i.e. the $$\varepsilon$$) follows a standard Gumbel distribution. With that assumption, the probability of choosing alternative $$j$$ is:
$$\Pr(\text{choosing }j) = \Pr(j\text{ offers highest utility}) = \frac{\exp(\alpha'X_j)}{\sum_{\text{all }j} \exp(\alpha'X_j)}$$
The log likelihood is then
$$LL = \sum_i \left( \alpha'X_{c_i} - \log\left( \sum_j \exp(\alpha' X_j)\right) \right)$$
where $$c_i \in \{1, \dots, j\}$$ indidates the choice that $$i$$ makes.
Implementation:
I simulate the data using known preference parameters and estimate them using MLE as below.
num_choices <- 100
xx <- mvtnorm::rmvnorm(num_choices, sigma = diag(2)) # Alternatives' covariates
alpha <- c(0.05, 0.1) # Preference parameters, to be estimated
# Matrix of utilities
mat <- matrix(NA, nrow = 1000, ncol = num_choices)
for (i in 1:num_choices) {
mat[, i] <- sum(alpha * xx[i, ]) + evd::rgumbel(1000)
}
# Choosing the alternative that gives the highest utility
y <- max.col(mat)
# negative log likelihood
cl_nllik <- function(alpha) {
xa <- c(xx %*% alpha)
lse_xa <- log(sum(exp(xa)))
- sum( xa[y] - lse_xa )
}
# MLE estimate -- does NOT produce the true alpha values!
optim(c(0, 0), cl_nllik)
• Is there a reason the parameter $\alpha$ doesn't vary across categories- $Pr (\text {i chooses j})= \frac {\exp(\alpha_j^TX_{ij})}{\sum_g \exp(\alpha_g^TX_{ig})}$ – probabilityislogic Feb 10 '18 at 3:47
• Because in the conditional logit model the covariates $X_j$ only varies across choices $j$, not across choosers $i$. If the covariates vary both across $i$ and $j$, it's called a multinomial logit model (in the literature I'm familiar with) – Heisenberg Feb 10 '18 at 18:35
• More conceptually, consider the example when $X$ is the price of the alternatives. Then customers' preference for price should be the same across alternatives, hence $\alpha$ doesn't vary across categories. I don't see a theoretical reason why price should have a different effect on customer's utilities depending on what alternatives are being considered. – Heisenberg Feb 10 '18 at 19:14 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 9, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9094230532646179, "perplexity": 2251.4672267262386}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038066613.21/warc/CC-MAIN-20210412053559-20210412083559-00295.warc.gz"} |
http://ex-ample.blogspot.com/2009/09/lyon-vascular-tree-theory-blood.html | ## Monday, September 7, 2009
### lyon - vascular tree - theory - blood
Extension of Murray's law using a non-Newtonian model of blood flow
// <![CDATA[ for(i=15; i
Author(s): Revellin R (Revellin, Remi)1,2, Rousset F (Rousset, Francois)1,2, Baud D (Baud, David)3, Bonjour J (Bonjour, Jocelyn)1,2
Source: THEORETICAL BIOLOGY AND MEDICAL MODELLING Volume: 6 Article Number: 7 Published: MAY 15 2009
Times Cited: 0 References: 33 Citation Map
Abstract: Background: So far, none of the existing methods on Murray's law deal with the non-Newtonian behavior of blood flow although the non-Newtonian approach for blood flow modelling looks more accurate.Modeling: In the present paper, Murray's law which is applicable to an arterial bifurcation, is generalized to a non-Newtonian blood flow model (power-law model). When the vessel size reaches the capillary limitation, blood can be modeled using a non-Newtonian constitutive equation. It is assumed two different constraints in addition to the pumping power: the volume constraint or the surface constraint (related to the internal surface of the vessel). For a seek of generality, the relationships are given for an arbitrary number of daughter vessels. It is shown that for a cost function including the volume constraint, classical Murray's law remains valid (i.e. Sigma R-c = cste with c = 3 is verified and is independent of n, the dimensionless index in the viscosity equation; R being the radius of the vessel). On the contrary, for a cost function including the surface constraint, different values of c may be calculated depending on the value of n.
Results: We find that c varies for blood from 2.42 to 3 depending on the constraint and the fluid properties. For the Newtonian model, the surface constraint leads to c = 2.5. The cost function (based on the surface constraint) can be related to entropy generation, by dividing it by the temperature.
Conclusion: It is demonstrated that the entropy generated in all the daughter vessels is greater than the entropy generated in the parent vessel. Furthermore, it is shown that the difference of entropy generation between the parent and daughter vessels is smaller for a non-Newtonian fluid than for a Newtonian fluid. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 1, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6256965398788452, "perplexity": 1386.5312764980583}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-30/segments/1531676596542.97/warc/CC-MAIN-20180723145409-20180723165409-00189.warc.gz"} |
http://mathhelpforum.com/statistics/124753-very-easy-question.html | # Math Help - very easy question!
1. ## very easy question!
hello everyone!
i have a very easy question for you guys!!!! but very hard for me!!
can you tell me what is the pourcentage that 7+ a random number between 2 and 12 will be greater than 5 + a random number between 2 and 12?
if you could tell me how to find this out, if its not too hard, i would really appreciate it!!
i am working an a role playing game
Francois
2. Originally Posted by frankinthecity
hello everyone!
i have a very easy question for you guys!!!! but very hard for me!!
can you tell me what is the pourcentage that 7+ a random number between 2 and 12 will be greater than 5 + a random number between 2 and 12?
if you could tell me how to find this out, if its not too hard, i would really appreciate it!!
i am working an a role playing game
Here are a few questions for you first. What do you mean by "a random number between 2 and 12"? Do you mean a whole number, and are the values 2 and 12 included or do you mean an integer strictly between 2 and 12 (in other words not including the end points)? Also, when you say a "random" number, do you mean that each value from 2 to 12 is equally probable, or are you perhaps thinking of throwing two dice, in which case the result is much more likely to be 7 than 2 for example?
If you can state the problem a bit more precisely then we should be able to show you how to do the calculation.
3. Hello Opalg!
thank you for your help, you got it, its 2 six sided dice!
i understand now that if it is dice, its not exactly a ramdon number between 2 and 12!!! you have a lot more chances to get 7 like you say
no wonder i am having problem finding the answer, its a lot more complicated that i thought!!!
Francois
4. Okay, so this is more complicated than you first thought! In the table below, the top row shows the possible outcomes from 2 to 12 when you throw two dice. For each outcome, the second row shows the probability of that outcome occurring, and the bottom row shows the probability of the outcome being at least that much.
$\begin{array}{c|ccccccccccc}k&2&3&4&5&6&7&8&9&10&1 1&12\\ \\P(k)& \frac1{36} & \frac2{36} & \frac3{36} & \frac4{36} & \frac5{36} & \frac6{36} & \frac5{36}& \frac4{36}& \frac3{36} & \frac2{36}& \frac1{36}\\ \\ P(\geqslant k)& \frac{36}{36} & \frac{35}{36} & \frac{33}{36} & \frac{30}{36} & \frac{26}{36} & \frac{21}{36} & \frac{15}{36} & \frac{10}{36} & \frac6{36} & \frac3{36} & \frac1{36} \end{array}$
Now, if the first player (the one with a current score of 5) throws the dice and scores k, then the second player (currently with 7) needs to score at least k–1 in order for their total to remain greater than that of the other player. If the first player rolls the dice and gets 2 or 3, there is no way that they can go ahead. But if they get 4, then the second player must get at least 3. The probability of that happening is 3/36 (= probability of the first player scoring 4) times 35/36 (= probability of the second player scoring at least 3).
Adding up the probability for each of these combinations, the total probability of the second player remaining ahead after both players have rolled the dice is
$\frac{\parbox{5in}{1\times36 + 2\times 36 + 3\times35 + 4\times 33 + 5\times 30 + 6\times26\\ {\color{white}.}\hfill {}+ 5\times21 + 4\times 15 + 3\times10+2\times6+ 1\times3}}{36\times36}\approx 0.66435...$
If you want it as a percentage then the answer is approx. 66.4%.
5. Opalg, thank you so much
ok, i understand the first line, i even understand the second line lol
but the third i am not sure, listen, if its really too hard to explain on a forum, (i know forum have their limits hehe) just give me another exemple, how about 7 and 6? maybe i will be able to figure out by myself..
what i need is not complicated at all, i need something like this
(2 six sided dice = 2d6)
7+2d6 VERSUS 5+2d6 = 66%
7+2d6 VERSUS 6+2d6 =
7+2d6 VERSUS 7+2d6 = 50% (that one i found out by myself LOL)
7+2d6 VERSUS 8+2d6 =
7+2d6 VERSUS 9+2d6 =
7+2d6 VERSUS 10+2d6 =
8+2d6 VERSUS 5+2d6 =
8+2d6 VERSUS 6+2d6 = 66% (i think we can apply the same formula here??)
8+2d6 VERSUS 7+2d6 =
8+2d6 VERSUS 8+2d6 = 50%
8+2d6 VERSUS 9+2d6 =
8+2d6 VERSUS 10+2d6 =
9+2d6 VERSUS 5+2d6 =
9+2d6 VERSUS 6+2d6 =
9+2d6 VERSUS 7+2d6 = 66%
9+2d6 VERSUS 8+2d6 =
9+2d6 VERSUS 9+2d6 = 50%
9+2d6 VERSUS 10+2d6 =
10+2d6 VERSUS 5+2d6 =
10+2d6 VERSUS 6+2d6 =
10+2d6 VERSUS 7+2d6 =
10+2d6 VERSUS 8+2d6 = 66%
10+2d6 VERSUS 9+2d6 =
10+2d6 VERSUS 10+2d6 = 50%
11+2d6 VERSUS 5+2d6 =
11+2d6 VERSUS 6+2d6 =
11+2d6 VERSUS 7+2d6 =
11+2d6 VERSUS 8+2d6 =
11+2d6 VERSUS 9+2d6 = 66%
11+2d6 VERSUS 10+2d6 =
12+2d6 VERSUS 5+2d6 =
12+2d6 VERSUS 6+2d6 =
12+2d6 VERSUS 7+2d6 =
12+2d6 VERSUS 8+2d6 =
12+2d6 VERSUS 9+2d6 =
12+2d6 VERSUS 10+2d6 = 66%
if you give me the 7 and 6 exemple, and i can apply it to 8 and 7, 9 and 8, and so forth, there is only a few more i need to find!
Francois
6. This "very easy question" gets more and more complicated. The original question was "Can you tell me what is the percentage that 7+ a random number between 2 and 12 will be greater than 5 + a random number between 2 and 12?" The answer to the question depends on what is meant by "greater than". The natural interpretation is that A's score (x) is greater than B's score (y) if $x>y$. A second interpretation would be to allow also the possibility that $x=y$, and to say that A's score is greater if $x\geqslant y$. A third interpretation (which sounds strange but is actually quite natural) is to split the difference between the first two interpretations.
Suppose that A and B start out with equal scores. They then each throw a couple of dice. There is a probability of approximately 11.2% that they will both throw the same total, and a probability of about 44.4% that B will throw a higher score than A. So the probability that B then has the greater score is 44.4% if you use the first interpretation of "greater". It is 55.6% if you use the second interpretation, and it is 50% if you use the third interpretation and split the difference between 44.4% and 55.6%.
Originally Posted by frankinthecity
(2 six sided dice = 2d6)
7+2d6 VERSUS 5+2d6 = 66%
7+2d6 VERSUS 6+2d6 =
7+2d6 VERSUS 7+2d6 = 50% (that one i found out by myself LOL)
In those calculations, I used the first interpretation to get the 66%, but you used the third interpretation to get the 50%. If I had used the third interpretation then my answer would have been 7+2d6 VERSUS 5+2d6 = 71%.
7. if a and b or equal then it doesnt count and i start over, 1 number have to be higher then the other so its really the natural interpretation that is good.
and for the 7+2d6 VS 7+2d6, i didnt do the calculation to find out, i only said 50% because i said to myself "hey 7 and 7 chances or pretty equal must be 50%..." but again, myabe i am wrong??
so to keep it simple i will just ask
Can you tell me what is the percentage that 7+2d6 will be greater than 6 +2d6?
if you could to the same calculation like you did for the one before maybe i will figured it out and be able to calculate the other stats i need by myself
thank you again for you patience
Francois
8. i was able to figure it out, someone showed me how to work with PARI
thanks a bunch
Francois | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 5, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5849340558052063, "perplexity": 749.4580375873371}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1408500830834.3/warc/CC-MAIN-20140820021350-00177-ip-10-180-136-8.ec2.internal.warc.gz"} |
https://skepticalcommunity.com/viewtopic.php?p=1087424 | This is our lounge area. Feel free to come in and get acquainted!
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
Mrs. Camel is addicted, I am not. To the extent that I spend three or four hours a day cycling. In the dismal British Winter.
Stupid Americans suing one another over stupid things.
"She stole my lipstick!
"Officer Byrd, would you kindly escort this moron from the court?"
This should probably be in the "What The Fuck Is Going on in 'Murica" thread but I decided it deserved a new one.
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
You do not even want to contemplate the amount of money she makes per episode.
– J.D.
robinson
Posts: 19932
Joined: Sat Aug 12, 2006 2:01 am
Title: Je suis devenu Français
Location: USA
### Re: The Judge Judy Thread
asthmatic camel wrote: Tue Dec 07, 2021 7:23 am Stupid Americans suing one another over stupid things.
That's exactly the show!
It is fucking great sometimes. And all those people in the audience? They are paid to be there.
robinson
Posts: 19932
Joined: Sat Aug 12, 2006 2:01 am
Title: Je suis devenu Français
Location: USA
### Re: The Judge Judy Thread
Judy flies in, films enough shows for months, in a couple of days, flies back to her mansion, and doesn't even count the money.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
"Judgement in favor of the plaintiff in the amount of $35... now fuck off." Officer Burt is awesome. You Americans are lucky. We have Judge Rinder which is 642 levels of more shitter. asthmatic camel Posts: 20336 Joined: Sat Jun 05, 2004 1:53 pm Title: Forum commie nun. Location: Stirring the porridge with my spurtle. ### Re: The Judge Judy Thread Doctor X wrote: Tue Dec 07, 2021 7:44 am You do not even want to contemplate the amount of money she makes per episode. – J.D. I have a very, very good idea, Doc. You know, I'm qualified to act as an Idndependant Financial Advisor over here. I'm fucking good at it, too. BUT, and it's a BIG BUT, I'd have to deal with cretins who haven't the faintest idea about how the stock markets work, the relative risks of buying rental properties, when and when not to buy gold, etc. I could make a mint but it's too much fucking trouble. Last edited by asthmatic camel on Sun Dec 12, 2021 11:27 pm, edited 1 time in total. ed Posts: 42259 Joined: Tue Jun 08, 2004 11:52 pm Title: G_D ### Re: The Judge Judy Thread Buy ammo. https://i.dailymail.co.uk/i/pix/2013/06 ... 08x425.jpg "I doesn't bear thinking about" ceptimus Posts: 1473 Joined: Wed Jun 02, 2004 11:04 pm Location: UK ### Re: The Judge Judy Thread We used to have a TV series, Crown Court years ago, that was a better format than these modern 'judges' programs. It was fiction, written by scriptwriters, and the defendants, lawyers and judges were all played by actors - but the jury was twelve real members of the public. The show used to run over a few days - I forget how many - with each complete trial usually completed within a week. The script was written so that on Mondays you thought the defendant was guilty, Tuesdays you thought they were innocent, and by Wednesday you were never sure... I suppose if they bought the format back now, they could still have the jury, but you could also have an on-line vote of guilty or innocent, to see whether the public at home agreed with the jury's decision. asthmatic camel Posts: 20336 Joined: Sat Jun 05, 2004 1:53 pm Title: Forum commie nun. Location: Stirring the porridge with my spurtle. ### Re: The Judge Judy Thread Hotarubi wrote: Tue Dec 07, 2021 7:52 pm "Judgement in favor of the plaintiff in the amount of$35... now fuck off."
Officer Burt is awesome.
You Americans are lucky. We have Judge Rinder which is 642 levels of more shitter.
Sweet Bleeding Jeebus, how right you are.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
For the confused Americans - Judge Grindr
https://i.ibb.co/hBXffcm/1475758523-judge-rinder-strictly-come-dancing.jpg
Not that there's..
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
ceptimus wrote: Wed Dec 08, 2021 10:06 pm We used to have a TV series, Crown Court years ago, that was a better format than these modern 'judges' programs.
It was fiction, written by scriptwriters, and the defendants, lawyers and judges were all played by actors - but the jury was twelve real members of the public. The show used to run over a few days - I forget how many - with each complete trial usually completed within a week.
The script was written so that on Mondays you thought the defendant was guilty, Tuesdays you thought they were innocent, and by Wednesday you were never sure...
I suppose if they bought the format back now, they could still have the jury, but you could also have an on-line vote of guilty or innocent, to see whether the public at home agreed with the jury's decision.
FACTuals.
"Crown Court" was set in the fictional Town of Fulchester. As are all the stories in Viz magazine. No coincidence.
OI. Crown Court. Used to be on after ITN News at One and The Sullivans. Far more interesting than Pebble Mill or kipper tied twats on BBC2s Open University. I still remember one storyline vividly where a roadie had chucked an over enthusiastic groupie off a stage and she landed face first on a set of stage lights and blinded her.
Guys. Kids are watching this.
Thems were happy viewings though, those days when you had fooled Mam after pulling a sickie and got a few days off school. Pointless viewing on school holidays, mind.
During the war, I particularly rememb
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
ceptimus wrote: Wed Dec 08, 2021 10:06 pm
I suppose if they bought the format back now, they could still have the jury, but you could also have an on-line vote of guilty or innocent, to see whether the public at home agreed with the jury's decision.
It would also be hosted by a legal expert such as Rylan Neal-Clark.
Anaxagoras
Posts: 30178
Joined: Wed Mar 19, 2008 5:45 am
Location: Yokohama/Tokyo, Japan
### Re: The Judge Judy Thread
I think I may have seen bits of this show a long time ago, back when I lived in America. Apparently it ran for 25 years. Nothing recently.
Out of curiosity I googled her and found this:
One of the enduring mysteries of the last few decades is how Judy Sheindlin became the highest-paid woman on American television. Towards the end of Judge Judy’s 25-year run, Sheindlin was hauling in $47m a year (her estimated net worth is about$440m). Since the show only required her to work for 52 days a year, that meant she earned \$900,000 just by showing up. And this was Judge Judy, for crying out loud. It was a televised small-claims court. It was, by its very nature, mundane and repetitious.
Judge Judy: ‘If you decide to stay too long at the party, your makeup begins to fade.’
Judge Judy: 'Are my feelings PC and kumbaya? No. They are realistic'
And now it is over. Earlier this year, Sheindlin made the decision to hang up her gavel. You might not have noticed, since Judge Judy has been airing in reruns since then, and every episode is absolutely identical to every other episode. But while you or I might take this downtime as an opportunity to kick back and enjoy our mountains of unimaginable wealth, Sheindlin has not. For she already has a new show on IMDb TV. It’s called Judy Justice. And if you liked Judge Judy then, oh boy, are your rock-bottom expectations about to be expertly filled.
The format wasn't even original. You had The People's Court before it, which was an identical show with a different judge.
For almost a million dollars per episode. Can't say I blame her. If it works, it works. Nobody has to watch this if they don't want to. And she made almost half a billion doing it.
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
Hotarubi wrote: Wed Dec 08, 2021 10:56 pm For the confused Americans - Judge Grindr
https://i.ibb.co/hBXffcm/1475758523-judge-rinder-strictly-come-dancing.jpg
Not that there's..
Oh, brother Hotarubi, you're spot on.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
I have it on good authority , that JJ is more trustworthy than Clint Eastwood , but less so than Sandra Bullock.
And that is science intangibles fact.
ed
Posts: 42259
Joined: Tue Jun 08, 2004 11:52 pm
Title: G_D
### Re: The Judge Judy Thread
ceptimus wrote: Wed Dec 08, 2021 10:06 pm We used to have a TV series, Crown Court years ago, that was a better format than these modern 'judges' programs.
It was fiction, written by scriptwriters, and the defendants, lawyers and judges were all played by actors - but the jury was twelve real members of the public. The show used to run over a few days - I forget how many - with each complete trial usually completed within a week.
The script was written so that on Mondays you thought the defendant was guilty, Tuesdays you thought they were innocent, and by Wednesday you were never sure...
I suppose if they bought the format back now, they could still have the jury, but you could also have an on-line vote of guilty or innocent, to see whether the public at home agreed with the jury's decision.
What would be cool is if the penalty was death regardless of the crime. Then you could have a spin off called "Meet Justice". And merchandising ...
https://i.imgur.com/uNLpcmH.jpg
nonono We'll call it ... ""The Penalty Phase".... yeah, thats the ticket
You would open the show having the sentence reaffirmed
https://external-content.duckduckgo.com ... f=1&nofb=1
You'd need doleful music leading up to the execution then something chipper over the closing credits.
I like it. It could replace the Cuomo/Lemon crap on CNN.
Have your girl call my girl.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Absolutely nothing to do with executions or Judge Judy, but it was next to the crown court thing, so I thought I would indulge you.
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
I remember September 13th.
I also remember:
I almost need to play the campy Batman theme to wash the brain.
– J.D.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Doctor X wrote: Sat Dec 11, 2021 8:14 am https://i.ibb.co/QcMTmWx/Screenshot-20211211-110401-Chrome.jpg
Dipshit.
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
Move to a Real Country.
What you get for living in one of our colonies.
– J.D.
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
If I moved to the colony, I'd have to pay for all my meds, which I get here for nothing. I wouldn't be able to get insurance for pre-existing conditions and I'd be broke within a year. I'm staying here. (It's really quite beautiful where I live apart from the dismal weather.)
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Stockport is the 8th wettest city in the UK.
And the weather is pretty crap too.
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
Try moving to Wales. It's a beautiful country but much, much damper than Stockport. You and I should pay a visit sometime.
Here's my ancestral home.
https://www.nationaltrust.org.uk/chirk-castle
Last edited by asthmatic camel on Sun Dec 12, 2021 12:42 am, edited 1 time in total.
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
Can you handle all of the phlegm when the Welsh speak?
– J.D.
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
Doctor X wrote: Sat Dec 11, 2021 9:56 pm Can you handle all of the phlegm when the Welsh speak?
– J.D.
Indeed I can. My grandfather was a Welshman and spoke the language fluently. He taught me the basics when I was a boy but over the years most has been forgotten.
https://www.walesonline.co.uk/lifestyle ... ch-9557813
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
Here's another of my ancestral homes.
I shall refrain from boring you with Welsh history.
asthmatic camel
Posts: 20336
Joined: Sat Jun 05, 2004 1:53 pm
Title: Forum commie nun.
Location: Stirring the porridge with my spurtle.
### Re: The Judge Judy Thread
Hotarubi, it's Officer Byrd, you ignorant cunt. ;)
https://www.the-sun.com/news/3835506/wh ... udge-judy/
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
The Welsh seem to be focused on . . . sheep.
Not. . . .
– J.D.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
asthmatic camel wrote: Sun Dec 12, 2021 2:18 am Hotarubi, it's Officer Byrd, you ignorant cunt. ;)
https://www.the-sun.com/news/3835506/wh ... udge-judy/
They are American. Like the Welsh they have problems pronouncing things.
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
We know how to pronounce "Winner."
I can send you some literature on it. . . .
#totalwinyoulotworeredwalkedinstraightlinesnocentralheating
– J.D.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Doctor X wrote: Sun Dec 12, 2021 8:12 am We know how to pronounce "Winner."
What's Wehnuh?
Doctor X
Posts: 78936
Joined: Fri Jun 04, 2004 8:09 pm
Title: Collective Messiah
### Re: The Judge Judy Thread
Certainly not "Weiner."
– J.D.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Ok. I have watched a few episodes of JJs new show and what is clear, sadly, is that she is losing her mental faculties in very slow motion.
It's not too noticeable to start with, but there are instances where she laughs maniacally for no particular reason to the obvious embarrassment of her Clerk, reporter and obvious Bert clone who isn't and on occasion harangues defendants/plaintiffs for too long over irrelevant minutiae.
It's becoming car crash tv for the wrong (?) reasons. She should stop before it becomes a wiki paragraph.
ed
Posts: 42259
Joined: Tue Jun 08, 2004 11:52 pm
Title: G_D
### Re: The Judge Judy Thread
Drink likely.
robinson2
Posts: 934
Joined: Sun May 17, 2020 4:02 pm
Title: I can’t be worrying about that
### Re: The Judge Judy Thread
I stopped watching
She and Biden should retire
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
ed wrote: Fri Mar 25, 2022 10:48 amDrink likely.
You know what? I'd say if it was. But it isn't.
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
robinson2 wrote: Fri Mar 25, 2022 11:39 am I stopped watching
She and Biden should retire
As should you.
robinson2
Posts: 934
Joined: Sun May 17, 2020 4:02 pm
Title: I can’t be worrying about that
### Re: The Judge Judy Thread
I am retired!
Hotarubi
Posts: 5662
Joined: Fri Feb 14, 2020 2:12 am
Title: Enchantress
Location: This septic Isle.
### Re: The Judge Judy Thread
Couldn't agree more. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.26270338892936707, "perplexity": 16413.271984947707}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030337529.69/warc/CC-MAIN-20221004215917-20221005005917-00487.warc.gz"} |
https://www.swi-wiskunde.nl/swi2014/problems/nonlinear-cochlear-mechanics-incas3/ | # INCAS3 – Nonlinear Cochlear Mechanics #SWI2014
It is perhaps astonishing that in spite of the advances in medical imaging and other research techniques, the possibilities of visualizing damage to the human hearing system are very limited. Although there is a vast range of audiological tests that measure the effect of damage, pinpointing what is causing these effects is often impossible. This, unfortunately, results in a wide variety of hearing problems reported by people with very similar results on the audiological tests, and the corresponding uncertainty in estimating what is the best way to compensate for the hearing loss (see e.g. the development of ‘fitting-rules’ for estimating the required gain in hearing aids).
The reason for this is that the inner ear, where the conversion of movement to electrical impulses takes place, is very sensitive and vulnerable. For this reason, it is encased in the toughest bone in the human body, making it highly inaccessible. Measurements of cochlear action in vivo are scarce and can only be conducted in a small area of the cochlea of certain rodents. Insights into the mechanisms responsible for human hearing therefore heavily depend on models.
One such model was developed in cooperation between the departments of Biophysics and Applied Mathematics at Groningen University. This model simplifies the snail-shell shape of the cochlea to a rectangular box with the only longitudinal motion of the fluid and represents the organ of Corti (containing the hair cells that perform the mechano-electrical conversion) as a number (~400-1000) of individual sections behaving as harmonic oscillators. The excitation $$\zeta$$ of each section is governed by an equation of motion of the shape:
$$p =m\ddot{\zeta} + d\dot{\zeta} + s\zeta\tag{1}$$
where $$m$$ is the mass of the section, $$s$$ a stiffness restoring the section to its resting position and $$d$$ a damping term. The driving force is represented by $$m$$ and is fluid pressure. All oscillators are coupled via mass elements, representing an incompressible and inviscid fluid in the cochlear channels.
It was soon realized that this representation oversimplifies the mechanics of the organ of Corti, and in 1991 an additional term was introduced in the equation of motion:
$$p =m\ddot{\zeta} + d\dot{\zeta} + s\zeta + s^{\prime}\zeta_{t-\tau}\tag{2}$$
allowing realistic simulations of a wide range of experimental data (see Epp et al).
A problem remaining is the estimation of the values of $$m$$, $$d$$, $$s$$ and $$s^{\prime}$$. The problems with accessibility and vulnerability of the cochlea prevent measurements in vivo. Therefore the values are mostly found using fitting procedures and estimated guesswork. An additional complicating factor is the strongly nonlinear mechanics of the cochlea. In order to be able to code the impressive range of 120 dB covered by human hearing in nerve cells with a dynamic range of only about 40 dB, the cochlea contains a compressive nonlinearity. It is thought that at low input levels and active process amplifies the motion of the cochlear partition to increase the sensitivity of our hearing. Although there are tell-tale signs of such an amplification mechanism and including it in models leads to realistic results, the fact that direct measurement of hair cell motion is impossible still leaves room for a heated debate about its existence.
One of the strongest indicators of the ‘cochlear amplifier’ and a possible way to gain more insight into cochlear damage is found in OtoAcoustic Emissions (OAEs). These are thought to be byproducts of the amplification process measurable in the ear canal as weak sounds emanating from the cochlea. The nonlinearity of the mechanics of the cochlea can be used to separate the emissions from the stimulus evoking them, e.g. in the case of DPOAEs the stimulus consists of the sum of two sinusoids with frequencies $$f_1$$ and $$f_2$$ and the emission contains components at intermodulation frequencies $$m f_1 + n f_2$$ with $$n$$ and m[\latex] positive or negative integer numbers.
The question we pose is whether it is possible to use (any combination of) OAE data to derive the shape of the mechanical cochlear nonlinearity.
Any information on the nonlinearity in the cochlea may help to improve the model, leading to a better quantitative match between OAE and other measurements that may help to assess hearing damage. Also, information on the nonlinearity required in the model to achieve this better match may give tantalizing clues about the relationship between the simplified mechanics as represented by equation (2) and the micromechanics of the organ of Corti in the real cochlea. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 2, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.681247353553772, "perplexity": 669.0474822766773}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964363149.85/warc/CC-MAIN-20211205065810-20211205095810-00243.warc.gz"} |
http://sc3howto.blogspot.co.uk/2014/ | ## Friday, December 12, 2014
### Last Week's Notes
Note: This is here temporarily for the benefit of some students. It will move to Moodle and disappear form here
/* SuperCollider is an Object Oriented Language that is designed for music and audio. It is a Music V type language. that means, like MAX MSP, the sound generation runs on a different thread than the control stuff. In MAX / MSP, you see this represented by differented coloured patch connections. In SuperCollider, audio runs on a server. Because we don't have much time, I'm going to ask you take notes and then try stuff out later, not in class. I also will ask Pieman to put a tutorial up for you on Moodle. Hopefully you all have SuperCollider installed. When you tried opening it, you saw the screen divided in two parts. One part was the post window, filled with strange text and the other part was just blank and called untitled. The untitled window is where you write your code. When you want to run your code, you select it with your mouse and hit ctrl-enter if you are in windows or linux, or apple-enter if you are on a mac. On some computers, you may need to use the apple or control key on the right wide of your keyboard. Try this out later with a simple program: */ 4 + 4 /* When you highlight 4 + 4 and run it, 8 will print out in your post window. We're going to start out with working with sound design. Sound runs on the server. Therefore, we need to fist boot the server. There are a few ways to do this. If you look in the Language menu, one of the items is 'boot server'. Select that. The text in the little status bar at the bottom should change and turn green. you will also see output in the post window. Now that the server is booted, let's make some sound: */ ( SynthDef(\sine, { Out.ar(0, SinOsc.ar(440, 0, 0.2) ) }).play ) /* When you want it to stop, hit ctrl-period or apple-period. We are defining a SynthDef, sending it to the server and telling it to play. a synthDef is a description of how the server makes a sound. First it has the name, which starts with a \, then comman curly bracket, then all of the UGens. Out.ar is where the sound should come out. The channels start with 0, so this is on the left. Next is what should come out. SinOsc is a sinwav oscillator. It's running at 440 Hz, it's phase is 0, and it's amplitude is 0.2. Notice that these items have commas between them. Then we close all of our open parens and curly brackets Then a .play tells the whole thing to play. We can organise this better using variables. A variable is a container with a name. Like a box named sine. It can hold an object. */ ( SynthDef(\sine, { var sine; sine = SinOsc.ar(440, 0, 0.2); Out.ar(0, sine); }).play ) /* First we let SuperCollider know that we've got a variable named sine. We end that with a semicolon, so it knows that statement is done. Then we do an assignment. Don't read = as 'equals, read it as 'gets'. sine gets SinOac.ar. We've got a box named sine. We've put a sine oscillator in the box, to keep track of it. Then a semi colon, so it knows we're done with the assignment. Then Our.ar, saying what channel to go out on. And we tell it, put out whatever's in sine. Take the contents of the box and send it to the left speaker. Every line needs to be separated by semicolons. Later on, when you can't figure out why something isn't working, check the semi colons first. It's the most common mistake. I still forget them all the time. These sines all last forever, so let's try an envelope: */ ( SynthDef(\sinenv, { var sine, env; sine = SinOsc.ar(440, 0, 0.2); env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, sine * env); }).play ) /* we have added an extra variable called env We've put an EnvGen into it. env gets EnvGen.kr. An EnvGen is an envelope generator. First we tell it what envelope shape, then we do this doneAction:2 thing. When we're telling out what to play, we tell it to multiple the sine box by the env box. Let's do some ring modulation: */ ( SynthDef(\sinerm, { var sine, ringmod, env; sine = SinOsc.ar(440, 0, 0.2); ringmod = SinOsc.ar(30) * sine; env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, ringmod * env); }).play ) /* We've added a new variable called ringmod. Ring mod gets a new sinosc times the contents of the sine variable. When SuperCollider is looking at your code and it sees an assignment - the equals sign - it does everything on the right hand side of the assingment and puts the result of everything into the variable on the left. We've picked 30 Hz, because that's the frequency daleks use, but what if we want different frequencies? We could keep changing the synthdef: */ ( SynthDef(\sinerm, { var sine, ringmod, env; sine = SinOsc.ar(470, 0, 0.2); ringmod = SinOsc.ar(30) * sine; env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, ringmod * env); }).play ) ( SynthDef(\sinerm, { var sine, ringmod, env; sine = SinOsc.ar(810, 0, 0.2); ringmod = SinOsc.ar(30) * sine; env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, ringmod * env); }).play ) ( SynthDef(\sinerm, { var sine, ringmod, env; sine = SinOsc.ar(752, 0, 0.2); ringmod = SinOsc.ar(30) * sine; env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, ringmod * env); }).play ) /* Or, we could use a special kind of variable called an argument */ ( SynthDef(\sinermarg, { arg freq; var sine, ringmod, env; sine = SinOsc.ar(freq, 0, 0.2); ringmod = SinOsc.ar(30) * sine; env = EnvGen.kr(Env.perc, doneAction:2); Out.ar(0, ringmod * env); }).add ) /* We've declared the argument at the top. That uses the keyword arg. argument need to go before variables. So first you have the SynthDef and the name of it and the culry bracked. Then next is arguments, starting with the keyword arg. then are the variables, starting with the keyword var. Everything else is below that. It does not make sound when we play this one, because we changed the .play at the end to .add. Instead of playing this right away, we tell the server to remember it, so we can play it later. */ Synth(\sinermarg, [\freq, 440]) /* there are a lot of ways we can play a SynthDef, and one of them is by via Synth. The first argument to Synth is \sinermarg, which is the name of the synthdef. The next is this square bracket thing. The first thing in the square brackets is \freq, this is the name of our argument, but starting with a slash. Then is the value we want to give it. */ Synth(\sinermarg, [\freq, 860]) /* What if we want to have more arguments? */ ( SynthDef(\sinermargs, { arg freq, rm, dur, amp; var sine, ringmod, env; sine = SinOsc.ar(freq, 0, amp); ringmod = SinOsc.ar(rm) * sine; env = EnvGen.kr(Env.sine(dur), doneAction:2); Out.ar(0, ringmod * env); }).add ) Synth(\sinermargs, [\freq, 912, \rm, 123, \dur, 7, \amp, 0.3]) /* For this morning, we're going to focus more on SynthDefs, so we'll get to do sequences of notes in the afternoon. Let's try different waves, panned to centre */ ( SynthDef(\saw, { arg freq, dur, amp; var saw, env, panner; saw = Saw.ar(freq, amp); env = EnvGen.kr(Env.sine(dur), doneAction:2); panner = Pan2.ar(saw, 0,env); Out.ar(0, panner); }).add ) Synth(\saw, [\freq, 550, \dur, 3, \amp, 0.2]) /* Notice that saw and sign have different arguments in their list. the second thing in the list to sign is a 0 and the amplitude is third. But saw just goes directly from frequency to amplitude. How would you know about how these are different (or even what the various oscillators are)? the answer is in the help browser! Under the Help menu, there is a 'show help browser' option. You can click on search there to start searching. Or just browse around. Get to know the help browser. It is your friend. There are lots of examples. Let's try some filtered noise: */ ( SynthDef(\subtractive, { arg freq, dur, amp; var noise, filt, env, panner; noise = WhiteNoise.ar; filt = RLPF.ar(noise, freq); env = EnvGen.kr(Env.sine(dur), doneAction:2); panner = Pan2.ar(filt, 0,env * amp); Out.ar(0, panner); }).add ) Synth(\subtractive, [\freq, 1200, \dur, 3, \amp, 0.2]) /* WhiteNoise is just noise, so there's no need to give it additional information RLPF is a Resonant Low Pass Filter You may have noticed some of these are .ar and some are .kr. ar is audio rate kr is control rate The envelope doesn't need to change values as often as a 440 Hz sine oscillator in order to sound good. The oscillator needs to go through it's entire wave form 440 times a second, whereas, the envelope needs much less precision. */ /* This file is a SuperCollider file. The english text is in a comment. Programmers sometimes want to put human-language notes in their files. This makes the files more readable to humans, but the text is not meaningful to SuperCollider. They mark the text as not being code by putting comment markers around it. Every one of these block of text starts with a slash star and ends with a star slash. */ /* <-- this is the starts of a comment this is the end of a comment ---> */ // <- this marks a comment that only lasts for one line (and thus does not need an end marker)
### Pbind Notes from this morning
Note: This is here temporarily for the benefit of some students. It will go up on Moodle and then be removed from here.
/* Now what we want is a way to play notes in sequence. Let's use an earlier synthdef: */ ( SynthDef(\sin, { arg freq = 440, dur = 1, amp= 0.5, pan=0; var sine, env, panner; sine = SinOsc.ar(freq, 0, amp); env = EnvGen.kr(Env.perc(0.01, dur), doneAction:2); panner = Pan2.ar(sine, pan, env); Out.ar(0, panner); }).add ) ( Synth(\sin, [\freq, 440, \dur, 1, \amp, 0.3]); Synth(\sin, [\freq, 550, \dur, 1, \amp, 0.3]); Synth(\sin, [\freq, 660, \dur, 1, \amp, 0.3]); ) /* This plays all at once! Fortunately, there are several ways to add timings. One of these is Pbind. */ Pbind.new.play /* As before, press cntl-. or apple-. to stop Pbind makes a LOT of assumptions on your behalf, so you can run it with no arguments at all. Or you can specify as much as you want. Let's tell it to use our synthdef: */ ( Pbind( \instrument, \sin ).play ) /* Let's tell it to play louder */ ( Pbind( \instrument, \sin, \amp, 0.5 ).play ) // Change the freq and dur ( Pbind( \instrument, \sin, \amp, 0.5, \freq, 770, \dur, 0.5 ).play ) /* This is better, but let's make the notes change over time */ ( Pbind( \instrument, \sin, \amp, 0.5, \freq, Pseq([440, 550, 660, 770, 880], 1), \dur, 0.5 ).play ) /* Pseq plays all the array contents in order, then repeats the number of times listed */ ( Pbind( \instrument, \sin, \amp, 0.5, \freq, Pseq([440, 550, 660, 770, 880], 3), \dur, 0.4 ).play ) /* To repeat forever, use the keyword inf */ ( Pbind( \instrument, \sin, \amp, 0.5, \freq, Pseq([440, 550, 660, 770, 880], inf), \dur, 0.2 ).play ) /* We can use Pseqs for ANY item in a Pbind */ ( Pbind( \instrument, \sin, \amp, 0.5, \freq, Pseq([440, 550, 660, 770, 880], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* The first Pseq that ends, ends the entire Pbind Instead of specifying frequencies let's switch to scale degrees */ ( Pbind( \instrument, \sin, \amp, 0.5, \degree, Pseq([0, 2, 4, 6, 7], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* The Pbind does the maths for us to map the scale degrees to the frequency. This works because our synth uses the argument freq for frequency. the Pbind assumes this is what the frequency argument will be called and acts accordingly. We can change to a different number of scale steps */ ( Pbind( \instrument, \sin, \amp, 0.5, \stepsPerOctave, 10, \degree, Pseq([0, 2, 4, 6, 7], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* We can change scales */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Pseq([0, 2, 4, 6, 7], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* Look up scales in the help browser for more (incidentally, when you want to search, the search box at the top right searches only the currently displayed page. to search everything, click on the word 'search' on the top. We can do maths with Pseqs */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Pseq([0, 2, 4, 6, 7], inf) + Pseq ([0, 0, 0, 0, 0, 5, 5, 5, 5], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10) ).play ) /* We can nest Pseqs */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Pseq([0, 2, 4, 6, 7], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10) ).play ) /* They can also be multiplied, divided, etc. We can play multiple notes at once: */ ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Pseq([[1, 3], [3, 5, 7], [2, 5], 7, [1,8]], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* If a pseq gets an array back for any value, it will make as many notes as are in the array, each with one of the values in the array. So when it gets [3, 5, 7] for the degree, it makes one note with the 3rd, one with the 5th and one with the 7th. We can not always use direct sequences */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7], 3), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* Prand picks an item randomly from the array, the amount of times you tell it to. So rather than playing through everything 3 times, it picks 3 items */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2) ).play ) /* Prands can do all the same maths as Pseqs and work in combination with them */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7], inf) + Pseq ([0, 0, 0, 0, 0, 5, 5, 5, 5], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10) ).play ) ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7, [1, 3, 5]], inf) + Pseq ([0, 0, 0, 0, 0, 5, 5, 5, 5], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10) ).play ) ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7, [1, 3, 5]], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10) ).play ) /* Pwhite varies randomly between a low and a high number */ ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7, [1, 3, 5]], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1, 1, inf) ).play ) /* The panning is hard left, hard right or center, because it's only picking whole number. If we want it to pick numbers between the whole numbers, we need to specify that */ ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([0, 2, 4, 6, 7, [1, 3, 5]], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ).play ) /* The whole numbers are called intergers and the numbers with decimal points are called floating point or floats, which are terms you might see in the help files. */ /* This behaviour is actually useful, if we want to pick scale degrees, we may not what to pick ones in between */ ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Pwhite(0, 8, 10), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ).play ) ( Pbind( \instrument, \sin, \amp, 0.5, \scale, Scale.minor, \degree, Pwhite(0.0, 8.0, 10), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ).play ) /* What if we want moments of silence? we use the symbol \rest for the freq or degree */ ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Pseq([0, 2, \rest], 3), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ).play ) ( Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([1, 3, 5, 7, 8, [1, 3, 5], \rest], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ).play ) /* What if we want to do one thing and go on to another thing? */ ( Pseq([ Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([1, 3, 5, 7, 8, [1, 3, 5], \rest], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 2), \pan, Pwhite(-1.0, 1.0, inf) ), Pbind( \instrument, \sin, \amp, 0.3, \stepsPerOctave, 10, \degree, Pwhite(1, 10, 10), \dur, Prand([0.4, 0.6, 0.8], inf) ) ]).play ) ( Pseq([ Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Pseq([0, 2, \rest], 3), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ), Pbind( \instrument, \sin, \amp, 0.3, \stepsPerOctave, 10, \degree, Pwhite(1, 10, 10), \dur, Prand([0.4, 0.6, 0.8], inf) ) ]).play /* What if we don't just want chords, but want two streams going at once? */ ( SynthDef(\crapSnare, { arg amp, pan; var noise, env, panner; noise = WhiteNoise.ar; env = EnvGen.kr(Env.perc, doneAction:2); panner = Pan2.ar(noise, pan, env); Out.ar(0, panner * amp) }).add ) ( Ppar([ Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([1, 3, 5, 7, 8, [1, 3, 5], \rest], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ), Pbind( \instrument, \crapSnare, \amp, 0.2, \dur, 0.8 ) ]).play ) // note the snare never stops! // or moving the snare to the offbeat: ( Ppar([ Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([1, 3, 5, 7, 8, [1, 3, 5], \rest], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ), Pbind( \instrument, \crapSnare, \amp, 0.2, \dur, Pseq([0.4, Pseq([0.8], inf)], 1) ) ]).play ) /* to get rid of the first beat, we need to give it a rest for the freq. It does not matter that the synthDef doesn't take freq as an argument. This is just for the safe of the pbind */ ( Ppar([ Pbind( \instrument, \sin, \amp, 0.3, \scale, Scale.minor, \degree, Prand([1, 3, 5, 7, 8, [1, 3, 5], \rest], inf) + Pseq ([ Pseq([0], 5), Pseq([5], 4), Prand([0, 2, 5], 1) ], inf), \dur, Pseq([0.2, 0.2, 0.4, 0.2, 0.6], 10), \pan, Pwhite(-1.0, 1.0, inf) ), Pbind( \instrument, \crapSnare, \amp, 0.2, \dur, Pseq([0.4, Pseq([0.8], inf)], 1), \freq, Pseq([\rest, Pseq([440], inf)], 1), ) ]).play ) /* Ppars can also be nested in Pseqs. The helpfiles for streams patterns and events go into loads of detail about how to use p-things When you are making your own pbinds, watch out for forgetting commas in the middle of them, or dangling commas at the end. commas should go between items. */ /* Finally, we might have a synth that lasts for a really long time, that we want to change, but not end */ ( SynthDef(\sinerm, {arg freq, amp; var sine, ringmod, env; sine = SinOsc.ar(freq, 0, 0.2); ringmod = SinOsc.ar(30) * sine; Out.ar(0, ringmod * amp); }).play ) ( Pmono(\sinerm, \degree, Pwhite(0, 12, inf), \amp, 0.5, //\stepsPerOctave, 10, \db, -3 ).play ) // We can change the synthdef a bit to add some lag ( SynthDef(\sinermlag, {arg freq, amp; var sine, ringmod, env, lag; lag = Lag.kr(freq); sine = SinOsc.ar(lag, 0, 0.2); ringmod = SinOsc.ar(30) * sine; Out.ar(0, ringmod * amp); }).play ) ( Pmono(\sinermlag, \degree, Pwhite(0, 10, inf), \amp, 0.5, \stepsPerOctave, 10, \db, -3 // Pmono and Pbind will translate db to amp for us ).play ) /* Algorave: uses algorythms to generate dance music Can be live-coded, but need not be Examples: Microrex https://soundcloud.com/micorex Yee-king http://open.spotify.com/track/1UTiLOe4LwarRDWR5pmjZg Norah Lorway http://earthrid.bandcamp.com/album/ive-had-dreams-like-this */
### Some Notes for Students Today
Note: This is literally for some students I have today. It will appear on Moodle some time soon and then disappear from this space.
/* Extra Things! Q: How do you make a Pmono stop? A: A Pmono stops when it runs out of values, to send, just like a Pbind. However, unless we tell a synth to stop, it will keep going forever. Q: How do you tell a synth to stop? A: Envelopes! We've seen this already with fixed duration envelopes. But if we don't know from the start how long we want the synth to go for, when need to use a different kind of envelope. For example, and ASR. ASR stands for 'attack, sustain, release and is a very common envelope in electronic music. It uses a 'gate' to know when to start and stop. When the gate is 1, the envelope starts doing the attack, then it sustains indefinitely. As soon as the gate changes to 0, it immeditately stops whaever its doing to do the release portion. Ex: */ ( SynthDef(\blipGate, {|freq, amp, gate=1, pan| // the vertical bars are equvalent to using the keyword arg var blip, panner, env; blip = Blip.ar(freq, 10, 0.2); env = EnvGen.kr(Env.asr, gate, doneAction:2); // look at the helpfile for Env for more panner = Pan2.ar(blip, pan, env); Out.ar(0, panner * amp); }).add ) ( Pmono( \blipGate, \pan, Pwhite(0.0, 1.0, 5), \degree, Pwhite(1, 4, 5) ).play ) // gates also work with Pbinds ( Pbind( \instrument, \blipGate, \pan, Pwhite(0.0, 1.0, 5), \degree, Pwhite(1, 4, 5) ).play ) /* Q: How can I make frequency changes less abrupt? A: Add in some lag: */ ( SynthDef(\blipLag, {|freq, amp, gate=1, pan| // the vertical bars are equvalent to using the keyword arg var lag, blip, panner, env; lag = Lag.kr(freq); blip = Blip.ar(lag, 10, 0.2); env = EnvGen.kr(Env.asr, gate, doneAction:2); // look at the helpfile for Env for more panner = Pan2.ar(blip, pan, env); Out.ar(0, panner * amp); }).add ) ( Pmono( \blipLag, \pan, Pwhite(0.0, 1.0, 5), \degree, Pwhite(1, 4, 5) ).play ) /* Q: If you're live coding and want to change a pbind without stopping it, can you do that? A: Yes, with Pdef */ ( Pdef(\blips, Pbind( \instrument, \blipGate, \pan, Pwhite(0.0, 1.0, inf), \degree, Pwhite(1, 4, inf), \dur, 0.4 ) ).play ) // just put a Pdef around the pbind // now, let's change without stopping ( Pdef(\blips, Pbind( \instrument, \blipGate, \pan, Pwhite(0.0, 1.0, inf), \degree, Pwhite(1, 4, inf), \dur, Prand([0.4, 0.2, 0.2, 0.8], inf) ) ).play ) // another change ( Pdef(\blips, Pbind( \instrument, \blipGate, \pan, Pwhite(0.0, 1.0, inf), \degree, Pwhite(1, 4, inf) * Pwhite(1, 2), \dur, Prand([0.4, 0.2, 0.2, 0.8], inf) ) ).play ) Pdef(\blips).fadeTime = 5; // tell it to fade changes in and out over 5 seconds Pdef(\blips).stop; // tell it to stop (but don't stop anything else, including other Pdefs) /* Q: what are some good oscillators? A: SinOsc Blip Formant Pulse Saw Klank // look at the help files for those Ok, now I want you folks to get to work making some sounds and patterns. I'll come around to answer questions, or you can pair up if you want. */
## Thursday, May 22, 2014
### How to keep an installation running
Writing a program that can make it through the length of a single 20 minute performance can sometimes be challenging, but installation code needs to run for a full day or sometimes weeks and keep going. The first step, of course, is to make your code as bug-free as possible. However, even in this case, your code will eventually crash, though no wrong doing of your own. Therefore, the thing to do is to recover gracefully.
The latest versions of SuperCollider are actually three programs running at once - the IDE; sclang, the language; and scserver, the audio server. Any one of these things can crash.
### SkipJack
SkipJack is an object that is like a Task, except that it survives cmd-period. It takes several arguments, the first of which is a function and the second of which is a number indication the wait time in between executions of the function.
SkipJack({"SkipJack".postln}, 2)
This code would print out SkipJack once every two seconds. The advantage of using SkipJack in this case is not that it will keep going after a comand-periiod, but rather that it's on a different thread than the rest of your program. If your main execution loop gets stuck some place and effectively dies, SkipJack will likely carry on. Therefore, we can use SkipJack to check on your main loop and try to revive it.
### Sclang
How can we tell your main thread is still running without also stopping if it stops? One way to check is by looking at a shared variable. Let's have a number. Every time we go through the loop, we can set it to 3. Meanwhile, SkipJack could be running with a duration roughly equivalent to how long it should take to get through our loop. It could subtract one from our number. If our main execution loop stops, that number will count down towards zero and then go negative.
var alive, click, dur, task; dur = 2; click = { alive = 3 }; task = Task({ inf.do({ "still allive".postln; click.value; dur.wait; }) }).play; SkipJack({ "are we alive?".postln; (alive <=0).if({ task.resume; task.play; "play!".postln; (alive <= -2).if({ 1.exit; }) }); alive = alive -1; }, dur);
If alive gets to zero, first we try to get the task running again. This sometimes works. If it fails, however, we call 1.exit, which causes all of sclang to exit. If we can't recover inside sclang, we can recover outside it.
### The Server
We'll need a separate loop to check on the server.
SkipJack({ Server.default.boot(onFailure:{}); Server.default.doWhenBooted({}, onFailure:{1.exit}); }, dur);
This may look odd because it changes the 'onFailure' argument, but the effect of it is that if the server is not already booted, it will take a moment and may struggle to boot. If it fails, all of SuperCollider exits.
### Keeping a Synth Alive
If your loop is firing off new Synths, you don't need to worry about whether each individual synth keeps going, but if you're just changing parameters on an individual synth that keeps running, you also need to watch out for it perishing. there are a few ways to do this. Maybe you want to check if it has gone silent?
( var syn, lastrms, max_silence; SynthDef(\stereoListenForSilence, {|in=0, out=0| var input; input = In.ar(in, Server.default.options.numOutputBusChannels); SendPeakRMS.kr(input, 1, 3, '/loudnessMonitoring'); // send the RMS once per second ReplaceOut.ar(0, LeakDC.ar(input).tanh); // Optional line to get rid of offset and peaking }).add; /* ... */ Synth(\stereoListenForSilence, nil, RootNode(s), \addToTail); max_silence = 10; // 10 seconds lastrms=Array.fill(max_silence, {1}); osc_listener = OSCFunc({ |msg| var rms; rms = msg[4].asFloat.max(msg[6].asFloat); lastrms.removeAt(0); lastrms.add(rms); (lastrms.sum <= 0.0001).if ({ "too quiet".postln; // retsart your synths s.freeAll; Synth(\myAmazingSynthDef); Synth(\stereoListenForSilence, nil, RootNode(s), \addToTail); }); }, '/loudnessMonitoring');
You can put a monitoring Synthdef on the server's root node and use SendPeakRMS to send OSC messages with the overall amplitude of all running synthdefs. Then, set up an OSCFunc to check if the peak amplitude has been near zero for too long. If it has, free everything and put up new synths. This will not tell you if your server freezes or if your monitoring synth stops sending OSC messages.
Or if you just want to check if an individual Synth is still running, you can use OSCFuncs and SkipJack together.
( var syn_alive, dur; dur =1; syn_alive = 3; SynthDef(\myAmazingSynthDef, { var sin, trig; SendTrig.kr(Impulse.kr(dur.reciprocal)); sin = SinOsc.ar; Out.ar(0, sin); }).add; /* ... */ Synth(\myAmazingSynthDef); OSCFunc({ arg msg, time; syn_alive = 3; },'/tr', s.addr); SkipJack({ (syn_alive <=0).if({ s.freeAll; Synth(\myAmazingSynthDef); (syn_alive <= -2).if({ 1.exit; }) }); syn_alive = syn_alive -1; }, dur); SkipJack({ Server.default.boot(onFailure:{}); Server.default.doWhenBooted({}, onFailure:{1.exit}); }, dur); )
Try quitting the Server via the gui and everything gets back to where it was in under 3 seconds.
### No IDE
Previously in this document, we've intentionally made sclang crash, which, if you're running the IDE, is no fun. However, we will not be running sclang through the IDE. Instead, we'll run it from a BASH script. On your computer (if you have a mac or unix), when you open a terminal, what's running in it is a Bash shell. You can write scripts for this shell, which you edit in a plain text editor.
#!/bin/bash while true do /path/to/sclang installation.scd sleep 1 killall scsynth sleep 1 done
Ok, so first things first, open a terminal and type:
which bash
It may be /bin/bash or /usr/bin/bash. It's what you want in the first line of the bash script. So if you get back /usr/bin/bash, change the first line to #!/usr/bin/bash.
To find the path to sclang, you can try typing 'which sclang', but if you're on a mac, this is not going to work. Instead, you will need to find the SuperCollider application on you hard drive. Right click on it to examine package contents. If you poke around in there in folders called things like Resources or MacOs, you will eventually find sclang. Drag that file to your SuperCollider IDE to find out the path for it. Put that path into your bash script in the place of '/path/to/sclang'.
Save the script as installation.sh and save your supercollider file as installation.scd. Put them together in the same folder or directory. In your terminal window, cd to that directory and type:
chmod +x installation.sh
Or, alternately, if you'd prefer to use a GUI, get information about the installation.sh file and click a checkbox to make it executable.
What this script does is loop forever. It runs your program. When your program exists, it kills whatever server might still be running and then restarts your program. If your program crashes out entirely, this script will restart it.
### Helper Apps
If your installation relies on a helper application, like let's say you're using PD to manage HID communications, you'll want that in your loop also, but as both applications are running at the same time, you'll need to run the helper application in the background, but keep track of the PID so you can kill it when your program crashes.
#!/bin/bash while true do /path/to/pd hid_helper.pd & pid=$! /path/to/sclang installation.scd sleep 1 killall scsynth kill$pid sleep 1 done
Make sure your hid_helper is in the same folder as as your other files. Find the path to pd in the same way you got the path to sclang. The & makes it run in the background and the next line tracks the PID, so you can kill it later.
Obviously, you'll also want to keep track of your helper application, which you can do via OSC in the same way you keep track of your synthdefs. If your helper application quits, you'll need to do a 1.exit to force the bash script to restart everything.
### Making it all go
This is an installation, so if you're using your own laptop, don't run it as yourself. Make a new user account and don't give that user administrative rights. Make all your files READABLE by that user (or everyone on the system), but don't give that user write access. Set the system so that when it boots up, it automatically logs in as that user.
Log in to the system as the new user. Go to the settings and say you want to autostart an application on login. The application you want to autostart is installation.sh
Try booting your computer. Does it start your installation? Once you've got that sorted out, leave it running in your living room for days and days until you think you're losing your mind. Every so often, use the process manager to kill the server or the helper application or wiggle a wire or otherwise create a bit of problems and see if your installation survives. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.505402684211731, "perplexity": 8489.638186361419}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886108268.39/warc/CC-MAIN-20170821114342-20170821134342-00354.warc.gz"} |
https://www.birs.ca/events/2017/5-day-workshops/17w5133/videos/watch/201711131534-Makarychev.html | ## Video From 17w5133: Approximation Algorithms and the Hardness of Approximation
Monday, November 13, 2017 15:34 - 16:05
Algorithms for Stable and Perturbation-Resilient Problems | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9003728032112122, "perplexity": 7708.068244541925}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-05/segments/1642320304749.63/warc/CC-MAIN-20220125005757-20220125035757-00418.warc.gz"} |
https://downloads.haskell.org/~ghc/9.2.5/docs/html/libraries/ghc-9.2.5/GHC-StgToCmm-Foreign.html | ghc-9.2.5: The GHC API
GHC.StgToCmm.Foreign
Synopsis
# Documentation
Emit code for a foreign call, and return the results to the sequel. Precondition: the length of the arguments list is the same as the arity of the foreign function.
Produce code to save the current thread state to CurrentTSO
Save STG registers
STG registers must be saved around a C call, just in case the STG register is mapped to a caller-saves machine register. Normally we don't need to worry about this the code generator has already loaded any live STG registers into variables for us, but in hand-written low-level Cmm code where we don't know which registers are live, we might have to save them all.
Restore STG registers (see emitSaveRegs)
Push a subset of STG registers onto the stack, specified by the bitmap
Sometimes, a "live" subset of the STG registers needs to be saved on the stack, for example when storing an unboxed tuple to be used in the GHCi bytecode interpreter.
The "live registers" bitmap corresponds to the list of registers given by tupleRegsCover, with the least significant bit indicating liveness of the first register in the list.
Each register is saved to a stack slot of one or more machine words, even if the register size itself is smaller.
The resulting Cmm code looks like this, with a line for each real or virtual register used for returning tuples:
... if((mask & 2) != 0) { Sp_adj(-1); Sp(0) = R2; } if((mask & 1) != 0) { Sp_adj(-1); Sp(0) = R1; }
See Note [GHCi tuple layout]
Pop a subset of STG registers from the stack (see emitPushTupleRegs)
Produce code to load the current thread state from CurrentTSO | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.20557208359241486, "perplexity": 3821.1135308883877}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296943589.10/warc/CC-MAIN-20230321002050-20230321032050-00011.warc.gz"} |
https://ask.sagemath.org/question/10726/question-about-unit-conversion-and-feature-request/ | # Question about unit conversion and feature request. edit
I frequently need to convert units and I find sage very useful in doing that. However, sage does not support conversion to natural units which is frequently used in particle physics. So I have to keep multiplying expressions by $\hbar$ and $c$ in each notebook. Is there a more efficient way to convert quantities from SI to natural units. Does anyone have a idea so that sage can automatically identify the length, mass and time dimension and multiply by appropriate power of $\hbar$ and $c$. Also how difficult would it be to include this feature in sage?
Let me give a brief explanation of what natural units are. All the quantities in natural units are generally expressed a power of energy and $c$ and $\hbar$ are set to one. So one over length is equal to energy etc.
edit retag close merge delete | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.570679247379303, "perplexity": 395.52888914490666}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-45/segments/1603107888402.81/warc/CC-MAIN-20201025070924-20201025100924-00678.warc.gz"} |
https://fedemengo.github.io/blog/2019/01/FastBFT.html | # Federico Mengozzi
Distributed databases
# Scalable Byzantine Consensus via Hardware-assisted Secrete Sharing
Fastest and most scalable BFT protocol
Scalable Byzantine Consensus via Hardware-assisted Secrete Sharing
The author of this paper described FastBFT a new BFT protocols, highly scalable that achieve better performances than any other BFT protocols. The protocol was designed by studying the weakness of other popular protocols such as PBFT, Zyzzyva, BChain and MiniBFT to improve upon them. There are several components that characterize the paper.
The protocol is an hybrid protocol that require hardware assistance (so it only require $2f+1$ nodes in the network) based on a optimistic paradigm (requests are executed before reaching the agreement) that require only $f+1$ active replica to agree and execute a transaction while the other $f$ passive replicas are updates by the network.
## Message aggregation
To reach the agreement in BFT protocols, $O(n^2)$ messages are required since every replica $S_i$ multicast a commit message (in the general case) to all other active replicas in the network. The $O(n^2)$ message complexity represent the main bottleneck in PBFT.
During the commit phase of the protocol, each replica sends a commit message directly to the primary instead of multicasting the message to the network. To reduce the overhead of message aggregation the authors use secret sharing instead of a classical multisignatures approach.
To implement secret sharing, an additional phase of pre-processing it’s necessary to set up the “secret shares”.
### Pre-processing
In this phase the primary/leader $S_p$ generates a set of random secrets and publish a cryptographic hash of each of them (each secret will be bound to a single requests in the prepare phase). Then $S_p$ creates $f+1$ shares (and its hash as well) of the message and send one share to each active replica.
In the commit phase, every replica will reveals its share to the primary that will reconstruct the secret (if it receives enough valid shares). The secret is the multicasted by $S_p$ to all the replicas that can verify it (they verify that the hash previously bound to the request is actually correct).
To ensure that $S_p$ doesn’t impersonate any other $S_i$ the generation of secrete, hash, shares and binding happens inside the TEE (Trusted Execution Environment) and each secret is bound to a monotonic counter (as well as a single request).
## Communication topology
To further improve the exchange of messages, the network is organized (by the primary) in a balance tree structure rooted at $S_p$. Instead of receiving all $n$ messages from the replicas, the primary take advantage of the tree topology that will allow it to receive a constant number of messages (equal to the branching factor of each node, in the simplest case $n = 2$).
### Failure detection
Crashes are detected by timeout while Byzantine faults are detected by verifying shares: when a node $S_i$ receive a message from one of its children its check whether the aggregate shares is valid. If the shares received are wrong, the node will directly send a SUSPECT message to its parent (hence aborting the transaction), the message will eventually reach the primary that will be in charge of rearranging the network by putting the suspected faulty node in one of the leaves. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.239431694149971, "perplexity": 1995.790447893175}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662529538.2/warc/CC-MAIN-20220519141152-20220519171152-00153.warc.gz"} |
http://math.stackexchange.com/questions/280940/construction-of-a-valuation-ring-via-zorns-lemma-except-not | # Construction of a Valuation Ring via Zorn's Lemma, except not
In Atiyah & MacDonald they provide an abstract way to construct valuation rings, I'm curious how easy it is to work this out in general. As a refresher let $K$ be a field, $L$ an algebraically closed field and $\mathcal V$ be the set of ordered pairs $(A,f)$ where $A$ is a subring of $K$ and $f: A \rightarrow L$ is a homomorphism. In particular ordering $\mathcal V$ by $(A,f) \leq (A^\prime,f^\prime)$ if $A \subset A^\prime$ and $f^\prime |_A=f$, Atiyah & Macdonald show any maximal element of $\mathcal V$ is a valuation ring.
I was able to show that when $K=\mathbb Q$ and $L=\bar{\mathbb Z_p}$ that $\mathbb Z_{(p)}$ is a maximal element, are there any others? What are the maximal elements if we just take $K=\mathbb Q$ and $L=\bar{\mathbb Q}$. What if $K=\mathbb R$ and $L=\bar{\mathbb Z_2}$?
-
What is $\bar{\mathbb Z_p}$ ? Do you mean $\overline{\mathbb Q_p}$ ? – user18119 Jan 17 '13 at 22:30
@QiL No, I mean the algebraic closure of the field with $p$ elements. – JSchlather Jan 18 '13 at 1:17
Dear Jacob, I think this is a very bad notation. – user18119 Jan 18 '13 at 8:04
@QiL How do you denote the algebraic closure of the field with $p$ elements? – JSchlather Jan 18 '13 at 15:13
I meant $\mathbb Z_p$ usually denotes the ring of $p$-adic integers. For the field in $p$ element, $\mathbb F_p$ is the standard notation. – user18119 Jan 19 '13 at 20:16
Note that the construction in A-M gives rise to a valuation ring whose maximal ideal is the kernel of $f: A\to L$. In particular, if $L$ has characteristic $p$, then the valuation of $p$ is positive or infinite.
If $K=\mathbb Q$, by Ostrowski's theorem, any valuation on $K$ is $\ell$-adic for some prime $\ell$. The above remark implies that the construction of A-M gives the p-adic valuation on $\mathbb Q$.
If $K=\mathbb Q$ and $L=\overline{\mathbb Q}$ or any field of characteristic $0$, there is a unique ring homomorphism from $K$ to $L$ and it is the injective. So the maximal element is just $A=\mathbb Q$ corresponding to the trivial valuaton.
When $K$ is any field of characteristic $0$ and $L$ has characteristic $p>0$, then the maximal elements are extensions of the $p$-adic valuation on $\mathbb Q$. As soon as $K$ has a transcendental element over $\mathbb Q$, there are infinitely many such valuations. Indeed, this is true over a purely transcendental subfield $\mathbb Q(t)$ of $K$ (valuation rings : $\mathbb Q[t]_{(t-r)\mathbb Q[t]}$, for any $r\in \mathbb Q$), and A-M's construction shows that any valuation of $\mathbb Q(t)\subseteq K$ extends to $K$. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9500306248664856, "perplexity": 116.16798111444925}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-22/segments/1432207928754.15/warc/CC-MAIN-20150521113208-00011-ip-10-180-206-219.ec2.internal.warc.gz"} |
https://worldwidescience.org/topicpages/a/ae+star+hd.html | #### Sample records for ae star hd
1. The Herbig Ae Star HD 163296 in X-Rays
Science.gov (United States)
Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward
2004-01-01
Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT approximately 0.5 approximately kev), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least approximately 100 approximately G and perhaps as high as several kG.
2. The Herbig Ae star HD 163296 in X-rays
CERN Document Server
Swartz, D A; Elsner, R F; Ghosh, K K; Grady, C A; Wassell, E; Woodgate, B E; Kimble, R A; Swartz, Douglas A.; Drake, Jeremy J.; Elsner, Ronald F.; Ghosh, Kajal K.; Grady, Carol A.; Wassell, Edward; Woodgate, Bruce E.; Kimble, Randy A.
2005-01-01
Chandra X-ray imaging spectroscopy of the nearby Herbig Ae star HD 163296 at 100 AU angular resolution is reported. A point-like, soft (kT~0.5 keV), emission-line source is detected at the location of the star with an X-ray luminosity of 4.0e29 erg/s. In addition, faint emission along the direction of a previously-detected Ly-alpha-emitting jet and Herbig-Haro outflow may be present. The relatively low luminosity, lack of a hard spectral component, and absence of strong X-ray variability in HD 163296 can be explained as originating from optically-thin shock-heated gas accreting onto the stellar surface along magnetic field lines. This would require a (dipole) magnetic field strength at the surface of HD 163296 of at least ~100 G and perhaps as high as several kG. HD 163296 joins the T Tauri star TW Hya in being the only examples known to date of pre-main-sequence stars whose quiescent X-ray emission appears to be completely dominated by accretion.
3. Photometric variability of the Herbig Ae star HD 37806
CERN Document Server
Rucinski, S M; Hareter, M; Pojmanski, G; Kuschnig, R; Matthews, J M; Guenther, D B; Moffat, A F J; Sasselov, D; Weiss, W W
2010-01-01
The more massive counterparts of T Tauri stars, Herbig Ae/Be stars, are known to vary in a complex way with no variability mechanism clearly identified. We attempt to characterize the optical variability of HD~37806 (MWC 120) on time scales ranging between minutes and several years. A continuous, one-minute resolution, 21 day-long sequence of MOST (Microvariability & Oscillations of STars) satellite observations has been analyzed using wavelet, scalegram and dispersion analysis tools. The MOST data have been augmented by sparse observations over 9 seasons from ASAS (All Sky Automated Survey), by previously non-analyzed ESO (European Southern Observatory) data partly covering 3 seasons and by archival measurements dating back half a century ago. Mutually superimposed flares or accretion instabilities grow in size from about 0.0003 of the mean flux on a time scale of minutes to a peak-to-peak range of <~0.05 on a time scale of a few years. The resulting variability has properties of stochastic "red" nois...
4. Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569
NARCIS (Netherlands)
Merin, B; Montesinos, B; Eiroa, C; Solano, E; Mora, A; D'Alessio, P; Calvet, N; Oudmaijer, RD; de Winter, D; Davies, JK; Harris, AW; Cameron, A; Deeg, HJ; Ferlet, R; Garzon, F; Grady, CA; Horne, K; Miranda, LF; Palacios, J; Penny, A; Quirrenbach, A; Rauer, H; Schneider, J; Wesselius, PR
2004-01-01
We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of HD 34282 and HD 141569, two pre-main sequence Herbig AeBe stars. Both objects have been reported to show "anomalous positions" in the HR diagram in the sense that they appear below the main sequence.
5. The Environment of the Optically Brightest Herbig Ae Star, HD 104237
Science.gov (United States)
Grady, C. A.; Woodgate, B.; Torres, Carlos A. O.; Henning, Th.; Apai, D.; Rodmann, J.; Wang, Hongchi; Stecklum, B.; Linz, H.; Williger, G. M.; Brown, A.; Wilkinson, E.; Harper, G. M.; Herczeg, G. J.; Danks, A.; Vieira, G. L.; Malumuth, E.; Collins, N. R.; Hill, R. S.
2004-06-01
We investigate the environment of the nearest Herbig Ae star, HD 104237, with a multiwavelength combination of optical coronagraphic, near-IR, and mid-IR imaging supported by optical, UV, and far-ultraviolet spectroscopy. We confirm the presence of T Tauri stars associated with the Herbig Ae star HD 104237, noted by Feigelson et al. We find that two of the stars within 15" of HD 104237 have IR excesses, potentially indicating the presence of circumstellar disks, in addition to the Herbig Ae star itself. We derive a new spectral type of A7.5Ve-A8Ve for HD 104237 and find log(L/Lsolar)=1.39. With these data, HD 104237 has an age of t~5 Myr, in agreement with the estimates for the other members of the association. HD 104237 is still actively accreting, with a conspicuous UV/far-UV excess seen down to 1040 Å, and is driving a bipolar microjet termed HH 669. This makes it the second, older Herbig Ae star now known to have a microjet. The presence of the microjet enables us to constrain the circumstellar disk to rExplorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985.
6. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412
OpenAIRE
Järvinen, S. P.; Hubrig, S.; Schöller, M; Ilyin, I; Carroll, T. A.; Korhonen, H.
2016-01-01
Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles...
7. ACCRETION VARIABILITY OF HERBIG Ae/Be STARS OBSERVED BY X-SHOOTER HD 31648 AND HD 163296
Energy Technology Data Exchange (ETDEWEB)
Mendigutía, I.; Brittain, S. [Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 (United States); Eiroa, C.; Meeus, G. [Departamento de Física Teórica, Módulo 15, Facultad de Ciencias, Universidad Autónoma de Madrid, P.O. Box 78, E-28049, Cantoblanco, Madrid (Spain); Montesinos, B. [Centro de Astrobiología, Departamento de Astrofísica (CSIC-INTA), ESAC Campus, P.O. Box 78, E-28691 Villanueva de la Cañada, Madrid (Spain); Mora, A. [GAIA Science Operations Centre, ESA, European Space Astronomy Centre, P.O. Box 78, E-28691, Villanueva de la Cañada, Madrid (Spain); Muzerolle, J. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Oudmaijer, R. D. [School of Physics and Astronomy, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom); Rigliaco, E., E-mail: imendig@clemson.edu [Department of Planetary Science, Lunar and Planetary Lab, University of Arizona, 1629, E. University Boulevard, 85719, Tucson, AZ (United States)
2013-10-10
This work presents X-Shooter/Very Large Telescope spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of 12 ultraviolet, optical, and near-infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 × 10{sup –7} and 4.50 × 10{sup –7} M{sub ☉} yr{sup –1} for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ∼15 yr. Averaged accretion luminosities derived from the Balmer excess are consistent with the ones inferred from the empirical calibrations with the emission line luminosities, indicating that those can be extrapolated to HAe stars. In spite of that, the accretion rate variations do not generally coincide with those estimated from the line luminosities, suggesting that the empirical calibrations are not useful to accurately quantify accretion rate variability.
8. Study of the properties and spectral energy distributions of the Herbig AeBe stars HD 34282 and HD 141569
CERN Document Server
Merin, B; Eiroa, C; Solano, E; Mora, A; D'Alessio, P; Calvet, N
2004-01-01
We present a study of the stellar parameters, distances and spectral energy distributions (SEDs) of HD 34282 and HD 141569, two pre-main sequence Herbig AeBe stars. Both objects have been reported to show anomalous positions' in the HR diagram in the sense that they appear below the main sequence. A significant result of this work is that both stars are metal-deficient. The {\\it Hipparcos} distance of HD 34282 is very uncertain and the current study places the star at the expected evolutionary position in the HR diagram, i.e. as a PMS star. The distance for HD 141569 found in this work matches the {\\it Hipparcos} distance, and the problem of its anomalous position is solved as a result of the low metallicity of the object: using the right metallicity tracks, the star is in the PMS region. The SEDs are constructed using data covering ultraviolet to millimetre wavelengths. Physical, non-parametric models, have been applied in order to extract some properties of the disks surrounding the stars. The disk around ...
9. Radio continuum observations of the Herbig Ae/Be stars HD 163296 and HR 5999
Science.gov (United States)
Brown, D. A.; Perez, M. R.; Yusef-Zadeh, F.
1993-01-01
Very Large Array (VLA) observations of the two bright Herbig Ae/Be stars HD 163296 and HR 5999 have been carried out at lambda 3.6 and 20 cm. We report the detection of a radio source at lambda 3.6 cm that may be associated with HD 163296. From the peak flux density of 0.39 mJy/beam area, we estimate a mass-loss rate of 1.8 x 10(exp -8) solar mass/yr if the flux is due to free-free emission in an ionized wind with spherical symmetry, assuming a terminal wind velocity of 200 km/s. HR 5999 was not detected at either wavelength. We discuss the results in terms of the stellar-driven and accretion-driven scenarios for line and wind formation in Herbig Ae/Be stars.
10. Accretion variability of Herbig Ae/Be stars observed by X-Shooter. HD 31648 and HD 163296
CERN Document Server
Mendigutía, I; Eiroa, C; Meeus, G; Montesinos, B; Mora, A; Muzerolle, J; Oudmaijer, R D; Rigliaco, E
2013-01-01
This work presents X-Shooter/VLT spectra of the prototypical, isolated Herbig Ae stars HD 31648 (MWC 480) and HD 163296 over five epochs separated by timescales ranging from days to months. Each spectrum spans over a wide wavelength range covering from 310 to 2475 nm. We have monitored the continuum excess in the Balmer region of the spectra and the luminosity of twelve ultraviolet, optical and near infrared spectral lines that are commonly used as accretion tracers for T Tauri stars. The observed strengths of the Balmer excesses have been reproduced from a magnetospheric accretion shock model, providing a mean mass accretion rate of 1.11 x 10^-7 and 4.50 x 10^-7 Msun yr^-1 for HD 31648 and HD 163296, respectively. Accretion rate variations are observed, being more pronounced for HD 31648 (up to 0.5 dex). However, from the comparison with previous results it is found that the accretion rate of HD 163296 has increased by more than 1 dex, on a timescale of ~ 15 years. Averaged accretion luminosities derived fro...
11. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters
OpenAIRE
Fumel, Aurelie; Boehm, Torsten
2011-01-01
Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigat...
12. Rotationally modulated variations and the mean longitudinal magnetic field of the Herbig Ae star HD 101412
CERN Document Server
Hubrig, S; Gonzalez, J F; Schoeller, M; Ilyin, I; Cure, M; Zejda, M; Cowley, C R; Elkin, V G; Pogodin, M A; Yudin, R V
2010-01-01
Despite of the importance of magnetic fields for the full understanding of the properties of accreting Herbig Ae/Be stars, these fields have scarcely been studied over the rotation cycle until now. One reason for the paucity of such observations is the lack of knowledge of their rotation periods. The sharp-lined young Herbig Ae star HD101412 with a strong surface magnetic field became in the last years one of the most studied targets among the Herbig Ae/Be stars. A few months ago we obtained multi-epoch polarimetric spectra of this star with FORS2 to search for a rotation period and to constrain the geometry of the magnetic field. We measured longitudinal magnetic fields on 13 different epochs distributed over 62 days. These new measurements together with our previous measurements of the magnetic field in this star were combined with available photometric observations to determine the rotation period. The search of the rotation period resulted in P=42.076+-0.01d. According to near-infrared imaging studies the...
13. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412
CERN Document Server
Järvinen, S P; Schöller, M; Ilyin, I; Carroll, T A; Korhonen, H
2016-01-01
Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magn...
14. The magnetic field of the pre-main sequence Herbig Ae star HD 190073
Science.gov (United States)
Catala, C.; Alecian, E.; Donati, J.-F.; Wade, G. A.; Landstreet, J. D.; Böhm, T.; Bouret, J.-C.; Bagnulo, S.; Folsom, C.; Silvester, J.
2007-01-01
Context: The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. Aims: The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. Methods: We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution, high signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Results: Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74± 10 G, does not vary detectably on a one-year timeframe, indicating either an azimuthally symmetric field, a zero inclination angle between the rotation axis and the line of sight, or a very long rotation period. The optical spectrum of HD 190073 exhibits a large number of emission lines. We discuss the formation of these emission lines in the framework of a model involving a turbulent heated region at the base of the stellar wind, possibly powered by magnetic accretion. Conclusions: .This magnetic detection contributes an important new observational discovery which will aid our understanding of stellar magnetism at intermediate masses. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.
15. Relating jet structure to photometric variability: the Herbig Ae star HD 163296
CERN Document Server
Ellerbroek, L E; Dougados, C; Cabrit, S; Sitko, M L; Sana, H; Kaper, L; de Koter, A; Klaassen, P D; Mulders, G D; Mendigutia, I; Grady, C A; Grankin, K; van Winckel, H; Bacciotti, F; Russell, R W; Lynch, D K; Hammel, H B; Beerman, L C; Day, A N; Huelsman, D M; Werren, C; Henden, A; Grindlay, J
2014-01-01
Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination...
16. The circumstellar disc around the Herbig AeBe star HD169142
CERN Document Server
Dent, W R F; Osorio, M; Calvet, N; Anglada, G
2006-01-01
We present 7 mm and 3.5 cm wavelength continuum observations toward the Herbig AeBe star HD169142 performed with the Very Large Array (VLA) with an angular resolution of ~1". We find that this object exhibits strong (~4.4 mJy), unresolved (~1") 7 mm continuum emission, being one of the brightest isolated Herbig AeBe stars ever detected with the VLA at this wavelength. No emission is detected at 3.5 cm continuum, with a 3 sigma upper limit of ~0.08 mJy. From these values, we obtain a spectral index of ~2.5 in the 3.5 cm to 7 mm wavelength range, indicating that the observed flux density at 7mm is most likely dominated by thermal dust emission coming from a circumstellar disc. We use available photometric data from the literature to model the spectral energy distribution (SED) of this object from radio to near-ultraviolet frequencies. The observed SED can be understood in terms of an irradiated accretion disc with low mass accretion rate, 10^{-8} solar masses per year, surrounding a star with an age of ~10 Myr....
17. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD101412
CERN Document Server
Schöller, M; Cahuasqui, J A; Drake, N A; Hubrig, S; Petr-Gotzens, M G; Savanov, I S; Wolff, B; Gonzalez, J F; Mysore, S; Ilyin, I; Jarvinen, S P; Stelzer, B
2016-01-01
Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD101412. We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He I lambda 10,830 and Pa gamma lines, formed in the accretion region. We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD101412 can be explained by rotational modulation of line profiles generated by accreting gas with a pe...
18. Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412
Science.gov (United States)
Järvinen, S. P.; Hubrig, S.; Schöller, M.; Ilyin, I.; Carroll, T. A.; Korhonen, H.
2016-03-01
Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp-lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well-studied targets among the Herbig Ae stars. High-resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magnetic field changes sign from negative to positive polarity. The distribution of field values obtained using Ti, Cr, and Fe lines is, however, completely different compared to the magnetic field values determined in previous low-resolution FORS 2 measurements, where hydrogen Balmer lines are the main contributors to the magnetic field measurements, indicating the presence of concentration of the studied iron-peak elements in the region of the magnetic equator. Further, we discuss the potential role of contamination by the surrounding warm circumstellar matter in the appearance of Zeeman features obtained using Ti lines. Based on data obtained from the ESO Science Archive Facility under request MSCHOELLER 101895 (ESO programme Nos. 081.C-0410(A), 085.C-0137(A), and 187.D-0917(D)).
19. Spectroscopic signatures of magnetospheric accretion in Herbig Ae/Be stars. I. The case of HD 101412
Science.gov (United States)
Schöller, M.; Pogodin, M. A.; Cahuasquí, J. A.; Drake, N. A.; Hubrig, S.; Petr-Gotzens, M. G.; Savanov, I. S.; Wolff, B.; González, J. F.; Mysore, S.; Ilyin, I.; Järvinen, S. P.; Stelzer, B.
2016-07-01
Context. Models of magnetically-driven accretion and outflows reproduce many observational properties of T Tauri stars. This concept is not well established for the more massive Herbig Ae/Be stars. Aims: We intend to examine the magnetospheric accretion in Herbig Ae/Be stars and search for rotational modulation using spectroscopic signatures, in this first paper concentrating on the well-studied Herbig Ae star HD 101412. Methods: We used near-infrared spectroscopic observations of the magnetic Herbig Ae star HD 101412 to test the magnetospheric character of its accretion disk/star interaction. We reduced and analyzed 30 spectra of HD 101412, acquired with the CRIRES and X-shooter spectrographs installed at the VLT (ESO, Chile). The spectroscopic analysis was based on the He iλ10 830 and Paγ lines, formed in the accretion region. Results: We found that the temporal behavior of these diagnostic lines in the near-infrared spectra of HD 101412 can be explained by rotational modulation of line profiles generated by accreting gas with a period P = 20.53d±1.68d. The discovery of this period, about half of the magnetic rotation period Pm = 42.076d previously determined from measurements of the mean longitudinal magnetic field, indicates that the accreted matter falls onto the star in regions close to the magnetic poles intersecting the line-of-sight two times during the rotation cycle. We intend to apply this method to a larger sample of Herbig Ae/Be stars. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme IDs 087.C-0124(A), 088.C-0218(A,B,C,E), 090.C-0331(A), and 092.C-0126(A).
20. Near-infrared interferometric observation of the Herbig Ae star HD144432 with VLTI/AMBER
CERN Document Server
Chen, Lei; Wang, Yang; Weigelt, Gerd; Hofmann, Karl-Heinz; Kraus, Stefan; Schertl, Dieter; Lagarde, Stephane; Natta, Antonella; Petrov, Roman; Robbe-Dubois, Sylvie; Tatulli, Eric
2012-01-01
We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD144432 with near-infrared (NIR) VLTI/AMBER observations to investigate the structure of its inner dust disk. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H- and K-band visibilities, the near- and mid-infrared visibilities from the literature, and the SED of HD144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. We derived a K-band ring-fit radius of 0.17 \\pm 0.01 AU and an H-band radius of 0.18 \\pm 0.01 AU (for a distance of 145 pc). This measured K-band radius of \\sim0.17 AU lies in the range between the dust sublimation radius of \\sim0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (\\sim0.27 AU). We found that an additional extended halo component is required in both the geometric and temperature-gradi...
1. Variability of Disk Emission in Pre-main-sequence and Related Stars. I. HD 31648 and HD 163296: Isolated Herbig Ae Stars Driving Herbig-Haro Flows
Science.gov (United States)
Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Wilde, J. Leon; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venterini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, R. Brad
2008-01-01
Infrared photometry and spectroscopy covering a time span of a quarter-century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 micron in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 micron region throughout this span of time. In both stars, the changes in the 1-5 micron flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly simultaneous photometric data.
2. Variability of Disk Emission in Pre-Main Sequence and Related Stars. I. HD 31648 and HD 163296 - Isolated Herbig Ae Stars Driving Herbig-Haro Flows
Science.gov (United States)
Sitko, Michael L.; Carpenter, William J.; Kimes, Robin L.; Lynch, David K.; Russell, Ray W.; Rudy, Richard J.; Mazuk, Stephan M.; Venturini, Catherine C.; Puetter, Richard C.; Grady, Carol A.; Polomski, Elisha F.; Wisnewski, John P.; Brafford, Suellen M.; Hammel, H. B.; Perry, Raleigh B.
2007-01-01
Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar flows with embedded Herbig-Haro (HH) objects. HD 163296 was found to be relatively quiescent photometrically in its inner disk region, with the exception of a major increase in emitted flux in a broad wavelength region centered near 3 pm in 2002. In contrast, HD 31648 has exhibited sporadic changes in the entire 3-13 pm region throughout this span of time. In both stars the changes in the 1-5 pm flux indicate structural changes in the region of the disk near the dust sublimation zone, possibly causing its distance from the star to vary with time. Repeated thermal cycling through this region will result in the preferential survival of large grains, and an increase in the degree of crystallinity. The variability observed in these objects has important consequences for the interpretation of other types of observations. For example, source variability will compromise models based on interferometry measurements unless the interferometry observations are accompanied by nearly-simultaneous photometric data.
3. Spectroscopic monitoring of the Herbig Ae star HD 104237. II. Non-radial pulsations, mode analysis and fundamental stellar parameters
CERN Document Server
Fumel, Aurelie
2011-01-01
Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. The evolutionary tracks of the earlier Herbig Ae stars cross a recently discovered PMS instability strip. Many of these stars exhibit pulsations of delta Scuti type. HD 104237 is a well-known pulsating Herbig Ae star. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile. To do this, we worked on dynamical spectra of equivalent photospheric (LSD) profiles of HD 104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present a mode identification corresponding to the detected dominan...
4. Relating jet structure to photometric variability: the Herbig Ae star HD 163296
NARCIS (Netherlands)
L.E. Ellerbroek; L. Podio; C. Dougados; S. Cabrit; M.L. Sitko; H. Sana; L. Kaper; A. de Koter; P.D. Klaassen; G.D. Mulders; I. Mendigutía; C.A. Grady; K. Grankin; H. van Winckel; F. Bacciotti; R.W. Russell; D.K. Lynch; H.B. Hammel; L.C. Beerman; A.N. Day; D.M. Huelsman; C. Werren; A. Henden; J. Grindlay
2014-01-01
Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the out
5. The compact H$\\alpha$ emitting regions of the Herbig Ae/Be stars HD 179218 and HD 141569 from CHARA spectro-interferometry
CERN Document Server
Mendigutía, I; Mourard, D; Muzerolle, J
2016-01-01
This work presents CHARA/VEGA H$\\alpha$ spectro-interferometry (R ~ 6000, and $\\lambda$/2B ~ 1 mas) of HD 179218 and HD 141569, doubling the sample of Herbig Ae/Be (HAeBe) stars for which this type of observations is available so far. The observed H$\\alpha$ emission is spatially unresolved, indicating that the size of the H$\\alpha$ emitting region is smaller than ~ 0.21 and 0.12 au for HD 179218 and HD 141529 (~ 15 and 16 R*, respectively). This is smaller than for the two other HAeBes previously observed with the same instrumentation. Two different scenarios have been explored in order to explain the compact line emitting regions. A hot, several thousand K, blackbody disc is consistent with the observations of HD 179218 and HD 141569. Magnetospheric accretion (MA) is able to reproduce the bulk of the H$\\alpha$ emission shown by HD 179218, confirming previous estimates from MA shock modelling with a mass accretion rate of 10^-8 Msun/yr, and an inclination to the line of sight between 30 and 50 degr. The H$\\al... 6. Gas and dust mass in the disk around the Herbig Ae star HD169142 CERN Document Server PaniÄ, Olja; Wilner, David; Qi, Chunhua 2008-01-01 We investigate the physical structure of the gas component of the disk around the pre-main-sequence star HD169142. The 13CO and C18O J=2-1 line emission is observed from the disk with 1.4'' resolution using the Submillimeter Array. We adopt the disk physical structure derived from a model which fits the spectral energy distribution of HD169142. We obtain the full three-dimensional information on the CO emission with the aid of a molecular excitation and radiative transfer code. This information is used for the analysis of our observations and previous 12CO J=2-1 and 1.3 mm continuum data. The disk is in Keplerian rotation and seen at an inclination close to 13 deg from face-on. We conclude that the regions traced by different CO isotopologues are distinct in terms of their vertical location within the disk, their temperature and their column densities. With the given disk structure, we find that freeze-out is not efficient enough to remove a significant amount of CO from gas phase. Both observed lines match t... 7. Monte-Carlo radiative transfer simulation of the circumstellar disk of the Herbig Ae star HD 144432 CERN Document Server Chen, L; Weigelt, G; Hofmann, K -H; Schertl, D; Malbet, F; Massi, F; Petrov, R; Stee, Ph 2015-01-01 Studies of pre-transitional disks, with a gap region between the inner infrared-emitting region and the outer disk, are important to improving our understanding of disk evolution and planet formation. Previous infrared interferometric observations have shown hints of a gap region in the protoplanetary disk around the Herbig Ae star HD~144432. We study the dust distribution around this star with two-dimensional radiative transfer modeling. We compare the model predictions obtained via the Monte-Carlo radiative transfer code RADMC-3D with infrared interferometric observations and the {\\SED} of HD~144432. The best-fit model that we found consists of an inner optically thin component at$0.21\\enDash0.32~\\AU$and an optically thick outer disk at$1.4\\enDash10~\\AU$. We also found an alternative model in which the inner sub-AU region consists of an optically thin and an optically thick component. Our modeling suggests an optically thin component exists in the inner sub-AU region, although an optically thick componen... 8. Inner disk clearing around the Herbig Ae star HD\\,139614: Evidence for a planet-induced gap ? CERN Document Server Matter, A; Augereau, J -C; Kluska, J; Crida, A; Carmona, A; Gonzalez, J F; Thi, W F; Bouquin, J -B Le; Olofsson, J; Lopez, B 2016-01-01 Spatially resolving the inner dust cavity of the transitional disks is a key to understanding the connection between planetary formation and disk dispersal. The disk around the Herbig star HD 139614 is of particular interest since it presents a pretransitional nature with an au-sized gap, in the dust, that was spatially resolved by mid-IR interferometry. Using new NIR interferometric observations, we aim to characterize the 0.1-10~au region of the HD~139614 disk further and identify viable mechanisms for the inner disk clearing. We report the first multiwavelength radiative transfer modeling of the interferometric data acquired on HD~139614 with PIONIER, AMBER, and MIDI, complemented by Herschel/PACS photometries. We confirm a gap structure in the um-sized dust, extending from about 2.5 au to 6 au, and constrained the properties of the inner dust component: e.g., a radially increasing surface density profile, and a depletion of 10^3 relative to the outer disk. Since self-shadowing and photoevaporation appears... 9. DISCOVERY OF A TWO-ARMED SPIRAL STRUCTURE IN THE GAPPED DISK AROUND HERBIG Ae STAR HD 100453 Energy Technology Data Exchange (ETDEWEB) Wagner, Kevin; Apai, Daniel [Department of Astronomy/Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Kasper, Markus [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching (Germany); Robberto, Massimo, E-mail: kwagner@as.arizona.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States) 2015-11-01 We present Very Large Telescope (VLT)/SPHERE adaptive optics imaging in the Y-, J-, H-, and K-bands of the HD 100453 system and the discovery of a two-armed spiral structure in a disk extending to 0.″37 (∼42 AU) from the star, with highly symmetric arms to the northeast and southwest. Inside of the spiral arms, we resolve a ring of emission from 0.″18 to 0.″25 (∼21–29 AU). By assuming that the ring is intrinsically circular we estimate an inclination of ∼34° from face on. We detect dark crescents on opposite sides (NW and SE) that begin at 0.″18 and continue to radii smaller than our inner working angle of 0.″15, which we interpret as the signature of a gap at ≲21 AU that has likely been cleared by forming planets. We also detect the ∼120 AU companion HD 100453 B, and by comparing our data to 2003 Hubble Space Telescope and VLT/NACO images we estimate an orbital period of ∼850 year. We discuss what implications the discovery of the spiral arms and finer structures of the disk may have on our understanding of the possible planetary system in HD 100453 and how the morphology of this disk compares to other related objects. 10. High-resolution Br-gamma spectro-interferometry of the transitional Herbig Ae/Be star HD 100546: a Keplerian gaseous disc inside the inner rim CERN Document Server Mendigutía, I; Oudmaijer, R D; Fairlamb, J R; Carciofi, A C; Ilee, J D; Vieira, R G 2015-01-01 We present spatially and spectrally resolved Br-gamma emission around the planet-hosting, transitional Herbig Ae/Be star HD 100546. Aiming to gain insight into the physical origin of the line in possible relation to accretion processes, we carried out Br-gamma spectro-interferometry using AMBER/VLTI from three different baselines achieving spatial and spectral resolutions of 2-4 mas and 12000. The Br-gamma visibility is larger than that of the continuum for all baselines. Differential phases reveal a shift between the photocentre of the Br-gamma line -displaced 0.6 mas (0.06 au at 100 pc) NE from the star- and that of the K-band continuum emission -displaced 0.3 mas NE from the star. The photocentres of the redshifted and blueshifted components of the Br-gamma line are located NW and SE from the photocentre of the peak line emission, respectively. Moreover, the photocentre of the fastest velocity bins within the spectral line tends to be closer to that of the peak emission than the photocentre of the slowest ... 11. Magnetic fields in PMS stars: HARPS spectropolarimetry of sharp-lined Herbig Ae stars OpenAIRE Järvinen, Silva P.; Carroll, Thorsten A.; Hubrig, Swetlana; Schöller, Markus; Ilyin, Ilya; Korhonen, Heidi H.; Feiden, Gregory A. 2016-01-01 Herbig Ae/Be-type stars are analogs of T Tauri stars in the higher mass range. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of their magnetic fields. We report the results of our HARPS high-resolution spectropolarimetric analysis of four Herbig Ae stars with low v sin i values: HD 101412, HD 104237, HD 190073, and PDS 2. The role of contamination by the surrounding wa... 12. Spatially and spectrally resolved 10 mu m emission in Herbig Ae/Be stars NARCIS (Netherlands) van Boekel, R; Waters, LBFM; Dominik, C; Dullemond, CP; Tielens, AGGM; de Koter, A 2004-01-01 We present new mid-infrared spectroscopy of the emission from warm circumstellar dust grains in the Herbig Ae stars HD 100546. HD 97048 and HD 104237, with a spatial resolution Of of approximate to0."9. We find that the emission in the UIR bands at 8.6, 11.3 and (HD 97048 only) 12.7 mum is extended 13. HARPS spectropolarimetry of Herbig Ae/Be stars CERN Document Server Hubrig, S; Schoeller, M; Curto, G Lo 2013-01-01 Our knowledge of the presence and the strength of magnetic fields in intermediate-mass pre-main-sequence stars remains very poor. We present new magnetic field measurements in six Herbig Ae/Be stars observed with HARPS in spectropolarimetric mode. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS spectra for six Herbig Ae/Be stars. Wavelength shifts between right- and left-hand side circularly polarised spectra were interpreted in terms of a longitudinal magnetic field , using the moment technique introduced by Mathys. The application of the moment technique to the HARPS spectra allowed us in addition to study the presence of the crossover effect and quadratic magnetic fields. Our search for longitudinal magnetic fields resulted in first detections of weak magnetic fields in the Herbig Ae/Be stars HD58647 and HD98922. Further, we confirm the previous tentative detection of a weak magnetic field in HD104237 by Donati et al. and confirm the previous detection of a... 14. A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk? CERN Document Server Carmona, A; Kamp, I; Baruteau, C; Matter, A; Ancker, M van den; Pinte, C; Kóspál, A; Audard, M; Liebhart, A; Sicilia-Aguilar, A; Pinilla, P; Regály, Zs; Güdel, M; Henning, Th; Cieza, L A; Baldovin-Saavedra, C; Meeus, G; Eiroa, C 2016-01-01 Context: Quantifying the gas content inside the dust gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the disk of HD 139614, a Herbig Ae star with a transition disk exhibiting a dust gap from 2.3 to 6 AU. Methods: We have obtained ESO/VLT CRIRES high-resolution spectra of CO ro-vibrational emission. We derive disk structure constraints by modeling the line profiles, the spectroastrometric signal, and the rotational diagrams using flat Keplerian disk models. Results: We detected v=1-0 12CO, 2-1 12CO, 1-0 13CO, 1-0 C18O, and 1-0 C17O ro-vibrational lines. 12CO v=1-0 lines have an average width of 14 km/s, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km/s narrower, and are dominated by emission at R>6 AU. The 12CO v=1-0 line profile indicates that if there is a gap in the gas it must be narrower than 2 AU. We find that a drop in the gas surface density (delta_gas)... 15. On the binarity of Herbig Ae/Be stars CERN Document Server Baines, D; Porter, J; Pozzo, M; Baines, Deborah; Oudmaijer, Rene; Porter, John; Pozzo, Monica 2005-01-01 We present high resolution spectro-astrometry of a sample of 28 Herbig Ae/Be and 3 F-type pre-main sequence stars. The spectro-astrometry is shown from both empirical and simulated data to be capable of detecting binary companions that are fainter by up to 6 magnitudes at separations larger than 0.1 arcsec. The nine targets that were previously known to be a binary are all detected. In addition, we report the discovery of 6 new binaries and present 5 further possible binaries. The resulting binary fraction of 68+/-11 per cent is the largest reported for any observed sample of Herbig Ae/Be stars, presumably because of the exquisite sensitivity of spectro-astrometry for detecting binary systems. The data hint that the binary frequency of the Herbig Be stars is larger than for the Herbig Ae stars. The appendix presents model simulations to assess the capabilities of spectro-astrometry and reinforces the empirical findings. Two objects, HD 87643 and Z CMa, display evidence for asymmetric outflows. Finally, the po... 16. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights CERN Document Server Järvinen, S P; Hubrig, S; Schöller, M; Ilyin, I; Korhonen, H; Pogodin, M; Drake, N A 2015-01-01 Several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be promising for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. High-resolution spectropolarimetric observations of the three sharp-lined Herbig Ae stars HD101412, HD104237, and HD190073 have been obtained in recent years with the HARPS. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition method. We discovered that different line... 17. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights ⋆ Science.gov (United States) Järvinen, S. P.; Carroll, T. A.; Hubrig, S.; Schöller, M.; Ilyin, I.; Korhonen, H.; Pogodin, M.; Drake, N. A. 2015-12-01 Aims: Recently, several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be a promising approach for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundances, and allow us to identify a proper sample of spectral lines appropriate for magnetic field determination. Methods: High-resolution spectropolarimetric observations of the three sharp-lined (vsini< 15 km s-1) Herbig Ae stars HD 101412, HD 104237, and HD 190073 have been obtained in recent years with the HARPS spectrograph in polarimetric mode. We used these archival observations to investigate the behaviour of their longitudinal magnetic fields. To carry out the magnetic field measurements, we used the multi-line singular value decomposition (SVD) method for Stokes profile reconstruction. Results: We carried out a high-resolution spectropolarimetric analysis of the Herbig Ae star HD 101412 for the first time. We discovered that different line lists yield differences in both the shape of the Stokes V signatures and their field strengths. They could be interpreted in the context of the impact of the circumstellar matter and elemental abundance inhomogeneities on the measurements of the magnetic field. On the other hand, due to the small size of the Zeeman features on the first three epochs and the lack of near-IR observations, circumstellar and photospheric contributions cannot be estimated unambiguously. In the SVD Stokes V spectrum of the SB2 system HD 104237, we detect that the secondary component, which is a T Tauri star, possesses a rather strong magnetic field ⟨Bz⟩ = 129 ± 12 G, while no significant field is present in the primary 18. Herbig Ae/Be Stars in nearby OB associations CERN Document Server Hernández, J; Hartmann, L; Briceño, C; Sicilia-Aguilar, A; Berlind, P; Hernandez, Jesus; Calvet, Nuria; Hartmann, Lee; Briceno, Cesar; Sicilia-Aguilar, Aurora; Berlind, Perry 2004-01-01 We have carried out a study of the early type stars in nearby OB associations spanning an age range of$\\sim$3 to 16 Myr, with the aim of determining the fraction of stars which belong to the Herbig Ae/Be class. We studied the B, A, and F stars in the nearby ($\\le 500$pc) OB associations Upper Scorpius, Perseus OB2, Lacerta OB1, and Orion OB1, with membership determined from Hipparcos data. We obtained spectra for 440 Hipparcos stars in these associations, from which we determined accurate spectral types, visual extinctions, effective temperatures, luminosities and masses, using Hipparcos photometry. Using colors corrected for reddening, we find that the Herbig Ae/Be stars and the Classical Be stars (CBe) occupy clearly different regions in the JHK diagram. Thus, we use the location on the JHK diagram, as well as the presence of emission lines and of strong 12 microns flux relative to the visual to identify the Herbig Ae/Be stars in the associations. We find that the Herbig Ae/Be stars constitute a small fr... 19. The evolved pulsating CEMP star HD112869 CERN Document Server Začs, L; Grankina, A; Deveikis, V; Kaminskyi, B; Pavlenko, Y; Musaev, F 2015-01-01 Radial velocity measurements,$BVR_C$photometry, and high-resolution spectroscopy in the wavelength region from blue to near infrared are employed in order to clarify the evolutionary status of the carbon-enhanced metal-poor star HD112869 with unique ratio of carbon isotopes in the atmosphere. An LTE abundance analysis was carried out using the method of spectral synthesis and new self consistent 1D atmospheric models. The radial velocity monitoring confirmed semiregular variations with a peak-to-peak amplitude of about 10 km$s^{-1}$and a dominating period of about 115 days. The light, color and radial velocity variations are typical of the evolved pulsating stars. The atmosphere of HD112869 appears to be less metal-poor than reported before, [Fe/H] = -2.3$\\pm$0.2 dex. Carbon to oxygen and carbon isotope ratios are found to be extremely high, C/O$\\simeq$12.6 and$^{12}C/^{13}C \\gtrsim$1500, respectively. The s-process elements yttrium and barium are not enhanced, but neodymium appears to be overabundan... 20. Photometric Observations of Two Cool Stars: HD 17025 and HD 38392 Science.gov (United States) Stȩpień, K. 1995-07-01 UBV(RI)c observations of a G6/G8IV star HD17025 suggest a variation period of about 9 days. The light curve has a marginal amplitude of about 0.015 of a magnitude but is poorly defined and needs an independent confirmation. No prominent chromospheric emission is visible in a spectrum of this star. The other observed star, a K2 dwarf HD38392, did not show measurable light variations over a two weeks period of observations. 1. Herbig AeBe stars: Multiplicity and consequences OpenAIRE Duchene, Gaspard 2014-01-01 By virtue of their young age and intermediate mass, Herbig AeBe stars represent a cornerstone for our understanding of the mass-dependency of both the stellar and planetary formation processes. In this contribution, I review the current state-of-the-art multiplicity surveys of Herbig AeBe stars to assess both the overall frequency of companions and the distribution of key orbital parameters (separation, mass ratio and eccentricity). In a second part, I focus on the interplay between the multi... 2. TRIGGERED STAR FORMATION SURROUNDING WOLF-RAYET STAR HD 211853 Energy Technology Data Exchange (ETDEWEB) Liu Tie; Wu Yuefang; Zhang Huawei [Department of Astronomy, Peking University, 100871 Beijing (China); Qin Shengli, E-mail: liutiepku@gmail.com [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany) 2012-05-20 The environment surrounding Wolf-Rayet (W-R) star HD 211853 is studied in molecular, infrared, as well as radio, and H I emission. The molecular ring consists of well-separated cores, which have a volume density of 10{sup 3} cm{sup -3} and kinematic temperature {approx}20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From the spectral energy distribution modeling toward the young stellar objects, the sequential star formation is revealed on a large scale in space spreading from the W-R star to the molecular ring. A small-scale sequential star formation is revealed toward core 'A', which harbors a very young star cluster. Triggered star formations are thus suggested. The presence of the photodissociation region, the fragmentation of the molecular ring, the collapse of the cores, and the large-scale sequential star formation indicate that the 'collect and collapse' process functions in this region. The star-forming activities in core 'A' seem to be affected by the 'radiation-driven implosion' process. 3. Triggered star formation surrounding Wolf-Rayet star HD 211853 CERN Document Server Liu, Tie; Zhang, Huawei; Qin, Sheng-Li 2012-01-01 The environment surrounding Wolf-Rayet star HD 211853 is studied in molecular emission, infrared emission, as well as radio and HI emission. The molecular ring consists of well-separated cores, which have a volume density of 10$^{3}$cm$^{-3}$and kinematic temperature$\\sim$20 K. Most of the cores are under gravitational collapse due to external pressure from the surrounding ionized gas. From SED modeling towards the young stellar objects (YSOs), sequential star formation is revealed on a large scale in space spreading from the Wolf-Rayet star to the molecular ring. A small scale sequential star formation is revealed towards core A, which harbors a very young star cluster. Triggered star formations is thus suggested. The presence of PDR, the fragmentation of the molecular ring, the collapse of the cores, the large scale sequential star formation indicate the "Collect and Collapse" process functions in this region. The star forming activities in core A seem to be affected by the "Radiation-Driven Implosion" (... 4. Magnetic fields of Herbig Ae/Be stars Directory of Open Access Journals (Sweden) Hubrig S. 2014-01-01 Full Text Available We report on the status of our spectropolarimetric studies of Herbig Ae/Be stars carried out during the last years. The magnetic field geometries of these stars, investigated with spectropolarimetric time series, can likely be described by centred dipoles with polar magnetic field strengths of several hundred Gauss. A number of Herbig Ae/Be stars with detected magnetic fields have recently been observed with X-shooter in the visible and the near-IR, as well as with the high-resolution near-IR spectrograph CRIRES. These observations are of great importance to understand the relation between the magnetic field topology and the physics of the accretion flow and the accretion disk gas emission. 5. The nature of the late B-type stars HD 67044 and HD 42035 CERN Document Server Monier, R; Royer, F 2016-01-01 While monitoring a sample of apparently slowly rotating superficially normal bright late B and early A stars in the northern hemisphere, we have discovered that HD 67044 and HD 42035, hitherto classified as normal late B-type stars, are actually respectively a new chemically peculiar star and a new spectroscopic binary containing a very slow rotator HD 42035 S with ultra-sharp lines (vsini = 3.7 km/s) and a fast rotator HD 42035 B with broad lines. The lines of Ti, Cr, Mn, Sr, Y, Zr and Ba are conspicuous features in the high resolution SOPHIE spectrum of HD 67044. The HgII line at 3983.93 A is also present as a weak feature. The composite spectrum of HD 42035 is characterised by very sharp lines formed in HD 42035 S superimposed onto the shallow and broad lines of HD 42035 B. These very sharp lines are mostly due to light elements from C to Ni, the only heavy species definitely present are Sr and Ba. Selected lines of 21 chemical elements from He up to Hg have been synthesized using model atmospheres compute... 6. Cometary Dust in the Debris of HD 31648 and HD163296: Two "Baby" Beta pictoris Stars Science.gov (United States) Sitko, Michael L.; Grady, Carol A.; Lynch, David K.; Russell, Ray W.; Hanner, Martha S. 1999-01-01 The debris disks surrounding the pre-main-sequence stars HD 31648 and HD 163296 were observed spectroscopically between 3 and 14 microns. Both stars possess a silicate emission feature at 10 Am that resembles that of the star P Pictoris and those observed in solar system comets. The structure of the band is consistent with a mixture of olivine and pyroxene material, plus an underlying continuum of unspecified origin. The similarity in both size and structure of the silicate band suggests that the material in these systems had a processing history similar to that in our own solar system prior to the time that the grains were incorporated into comets. 7. Stellar Companions to the Exoplanet Host Stars HD 2638 and HD 164509 CERN Document Server Wittrock, Justin M; Horch, Elliott P; Hirsch, Lea; Howell, Steve B; Ciardi, David R; Everett, Mark E; Teske, Johanna K 2016-01-01 An important aspect of searching for exoplanets is understanding the binarity of the host stars. It is particularly important because nearly half of the solar-like stars within our own Milky Way are part of binary or multiple systems. Moreover, the presence of two or more stars within a system can place further constraints on planetary formation, evolution, and orbital dynamics. As part of our survey of almost a hundred host stars, we obtained images at 692 nm and 880 nm bands using the Differential Speckle Survey Instrument (DSSI) at the Gemini-North Observatory. From our survey, we detect stellar companions to HD 2638 and HD 164509. The stellar companion to HD 2638 has been previously detected, but the companion to HD 164509 is a newly discovered companion. The angular separation for HD 2638 is$0.512 \\pm 0.002\\arcsec$and for HD 164509 is$0.697 \\pm 0.002\\arcsec$. This corresponds to a projected separation of$25.6 \\pm 1.9$AU and$36.5 \\pm 1.9$AU, respectively. By employing stellar isochrone models, we e... 8. Disk wind and magnetospheric accretion in emission from the Herbig Ae star MWC 480 Science.gov (United States) Tambovtseva, L. V.; Grinin, V. P.; Potravnov, I. S.; Mkrtichian, D. E. 2016-09-01 The young Herbig Ae star MWC 480 (HD 31648) is one of the comprehensively spectroscopically studied stars in the ultraviolet, optical, and infrared spectral ranges. Using non-LTE modeling of its hydrogen spectrum, we have calculated the contribution to the hydrogen emission from such important regions of the circumstellar environment as the disk wind and the magnetosphere. We have used our own observations of the stellar spectrum performed with the 2.4-m telescope at the Thai National Observatory to quantitatively check our theoretical calculations. In addition, all of the visible and infrared spectra available in the literature have been used for a qualitative comparison. The modeling results have revealed a significant role of the magneto-centrifugal disk wind in the formation of atomic hydrogen emission. The cause of the emission line variability in the spectrum ofMWC 480 is discussed. 9. Substellar Companions to Evolved Intermediate-Mass Stars: HD 145457 and HD 180314 CERN Document Server Sato, Bun'ei; Liu, Yujuan; Harakawa, Hiroki; Izumiura, Hideyuki; Kambe, Eiji; Toyota, Eri; Murata, Daisuke; Lee, Byeong-Cheol; Masuda, Seiji; Takeda, Yoichi; Yoshida, Michitoshi; Itoh, Yoichi; Ando, Hiroyasu; Kokubo, Eiichiro; Ida, Shigeru; Zhao, Gang; Han, Inwoo 2010-01-01 We report the detections of two substellar companions orbiting around evolved intermediate-mass stars from precise Doppler measurements at Subaru Telescope and Okayama Astrophysical Observatory. HD 145457 is a K0 giant with a mass of 1.9 M_sun and has a planet of minimum mass m_2sini=2.9 M_J orbiting with period of P=176 d and eccentricity of e=0.11. HD 180314 is also a K0 giant with 2.6 M_sun and hosts a substellar companion of m_2sin i=22 M_J, which falls in brown-dwarf mass regime, in an orbit with P=396 d and e=0.26. HD 145457 b is one of the innermost planets and HD 180314 b is the seventh candidate of brown-dwarf-mass companion found around intermediate-mass evolved stars. 10. Photometry of the extreme helium star HD 124448 International Nuclear Information System (INIS) The extreme helium star HD 124448 has been examined for photometric variability on time-scales ranging from hours to years. There is no evidence for light variations of more than 0.02 mag. Following a similar result for BD + 1002179, the criterion for pulsational instability in hot luminous hydrogen-deficient stars appears to be the luminosity to mass ratio of the star. (author) 11. Photometry of the extreme helium star HD 124448 Energy Technology Data Exchange (ETDEWEB) Jeffery, C.S.; Lynas-Gray, A.E. (Saint Andrews Univ. (UK). Observatory) 1990-01-01 The extreme helium star HD 124448 has been examined for photometric variability on time-scales ranging from hours to years. There is no evidence for light variations of more than 0.02 mag. Following a similar result for BD + 10{sup 0}2179, the criterion for pulsational instability in hot luminous hydrogen-deficient stars appears to be the luminosity to mass ratio of the star. (author). 12. The onset of cluster formation around Herbig Ae/Be stars OpenAIRE Testi, L.; Palla, F.; Natta, A. 1998-01-01 The large body of near infrared observations presented in Testi et al. (1997; 1998) are analysed with the aim of characterizing the young stellar clusters surrounding Herbig Ae/Be stars. The results confirm the tendency of early Be stars to be surrounded by dense clusters of lower mass "companions", while Ae stars are never found to be associated with conspicuous groups. The transition between the different environments appears to occur smoothly from Ae to Be stars without a sharp threshold. ... 13. HD 30963: a new HgMn star CERN Document Server Monier, R; Royer, F 2016-01-01 Using high dispersion high quality spectra of HD 30963 obtained with the echelle spectrograph SOPHIE at Observatoire de Haute Provence in November 2015, we show that this star, hitherto classified as a B9 III superficially normal star, is actually a new Chemically Peculiar star of the HgMn type. Spectrum synthesis reveals large overabundances of Mn, Sr, Y, Zr , Pt and Hg and pronounced underabundances of He and Ni which are characteristic of HgMn stars. We therefore propose that this interesting object be reclassified as a B9 HgMn star. 14. ALMA detection of the rotating molecular disk wind from the young star HD 163296 OpenAIRE Klaassen, P. D.; Juhasz, A.; Mathews, G. S.; Mottram, J. C.; de Gregorio-Monsalvo, I.; van Dishoeck, E. F.; Takahashi, S.; Akiyama, E.; Chapillon, E.; Espada, D.; Hales, A.; Hogerheijde, M.R.; Rawlings, M.; Schmalzl, M.; Testi, L. 2013-01-01 Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew ... 15. GASPS observations of Herbig Ae/Be stars with PACS/Herschel. The atomic and molecular content of their protoplanetary discs CERN Document Server Meeus, G; Mendigutia, I; Kamp, I; Thi, W F 2012-01-01 We observed a sample of 20 representative Herbig Ae/Be stars and five A-type debris discs with PACS onboard of Herschel. The observations were done in spectroscopic mode, and cover far-IR lines of [OI], [CII], CO, CH+, H2O and OH. We have a [OI]63 micron detection rate of 100% for the Herbig Ae/Be and 0% for the debris discs. [OI]145 micron is only detected in 25%, CO J=18-17 in 45% (and less for higher J transitions) of the Herbig Ae/Be stars and for [CII] 157 micron, we often found spatially variable background contamination. We show the first detection of water in a Herbig Ae disc, HD 163296, which has a settled disc. Hydroxyl is detected as well in this disc. CH+, first seen in HD 100546, is now detected for the second time in a Herbig Ae star, HD 97048. We report fluxes for each line and use the observations as line diagnostics of the gas properties. Furthermore, we look for correlations between the strength of the emission lines and stellar or disc parameters, such as stellar luminosity, UV and X-ray fl... 16. Search for exoplanet around northern circumpolar stars - Four planets around HD 11755, HD 12648, HD 24064, and 8 Ursae Minoris CERN Document Server Lee, B -C; Lee, S -M; Jeong, G; Oh, H -I; Han, I; Lee, J W; Lee, C -U; Kim, S -L; Kim, K -M 2015-01-01 Aims. This program originated as the north pole region extension of the established exoplanet survey using 1.8 m telescope at Bohyunsan Optical Astronomy Observatory (BOAO). The aim of our paper is to find exoplanets in northern circumpolar stars with a precise radial velocity (RV) survey. Methods. We have selected about 200 northern circumpolar stars with the following criteria: Dec. > 70 degree, 0.6 < B-V < 1.6, HIPPARCOS_scat < 0.05 magnitude, and 5.0 < mv < 7.0. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used for the RV survey. Chromospheric activities, the HIPPARCOS photometry, and line bisectors were analyzed to exclude other causes for the RV variations. Results. In 2010, we started to monitor the candidates and have completed initial screening for all stars for the last five years. We present the detection of four new exoplanets. Stars HD 11755, HD 12648, HD 24064, and 8 UMi all show evidence for giant planets in Keplerian motion. The companion ... 17. Spectral Analysis and Classification of Herbig Ae/Be Stars Science.gov (United States) Hernández, Jesús; Calvet, Nuria; Briceño, César; Hartmann, Lee; Berlind, Perry 2004-03-01 We present an analysis of the optical spectra of 75 early-type emission-line stars, many of which have been classified previously as Herbig Ae/Be (HAeBe) stars. Accurate spectral types were derived for 58 members of the sample; high continuum veiling, contamination by nonphotospheric absorption features, or a composite binary spectrum prevented accurate spectral typing for the rest. Approximately half of our sample exhibited [O I] λ6300 forbidden-line emission down to our detection limit of 0.1 Å equivalent width; a third of the sample exhibited Fe II emission (multiplet 42). A subset of 11 of the HAeBe sample showed abnormally strong Fe II absorption; 75% of this subset are confirmed UX Ori objects. Combining our spectral typing results with photometry from the literature, we confirm previous findings of high values of total-to-selective extinction (RV~5) in our larger sample, suggesting significant grain growth in the environments of HAeBe stars. With this high value of RV, the vast majority of HAeBe stars appear younger than with the standard RV=3.1 extinction law and are more consistent with being pre-main-sequence objects. 18. Optical spectroscopic variability of Herbig Ae/Be stars CERN Document Server Mendigutía, I; Montesinos, B; Mora, A; Oudmaijer, R D; Merín, B; Meeus, G 2011-01-01 We analysed 337 multi-epoch optical spectra of 38 Herbig Ae/Be (HAeBe) stars to gain insights into the variability behaviour of the circumstellar (CS) atomic gas. Equivalent widths (EWs) and line fluxes of the Halpha, [OI]6300, HeI5876 and NaID lines were obtained for each spectrum; the Halpha line width at 10% of peak intensity (W10) and profile shapes were also measured and classified. The mean line strengths and relative variabilities were quantified for each star. Simultaneous optical photometry was used to estimate the line fluxes. We present a homogeneous spectroscopic database of HAeBe stars. The lines are variable in practically all stars and timescales, although 30 % of the objects show a constant EW in [OI]6300, which is also the only line that shows no variability on timescales of hours. The HeI5876 and NaID EW relative variabilities are typically the largest, followed by those in [OI]6300 and Halpha. The EW changes can be larger than one order of magnitude for the HeI5876 line, and up to a factor ... 19. On the nature of the {delta} Scuti star HD 115520 Energy Technology Data Exchange (ETDEWEB) Pena, J H; Cervantes-Sodi, B; Cano, M; Sorcia, M A [Instituto de AstronomIa, Universidad Nacional Autonoma de Mexico, Mexico D.F., Apdo. Postal 70-264 (Mexico); Fox, L; Alvarez, M [Observatorio Astronomico Nacional, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada B.C., Apdo. Postal 877 (Mexico); Pena, R [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Mexico D.F. (Mexico); Munoz, G; Vargas, B [Escuela Superior de Ingenier Mecanica y Electrica, Instituto Politecnico Nacional, Av. IPN s/n, 07738 Mexico, D.F. (Mexico); Sareyan, J P [Observatoire de la Cote d' Azur (France)], E-mail: jhpena@astroscu.unam.mx 2008-10-15 Observing Delta Scuti stars is most important as their multi-frequency spectrum of radial pulsations provide strong constraints on the physics of the stars interior; so any new detection and observation of these stars is a valuable contribution to asteroseismology. While performing uvby-beta photoelectric photometry of some RR Lyrae stars acquired in 2005 at the Observatorio Astronomico Nacional, Mexico, we also observed several standard stars, HD115520 among them. After the reduction this star showed indications of variability. In view of this, a new observing run was carried out in 2006 during which we were able to demonstrate its variability and its nature as a Delta Scuti star. New observations in 2007 permitted us to determine its periodic content with more accuracy. This, along with the uvby-beta photoelectric photometry allowed us to deduce its physical characteristics and pulsational modes. 20. Asteroseismology of the$\\delta$Scuti star HD 50844 CERN Document Server Chen, X H; Lai, X J; Wu, T 2016-01-01 Aims. We aim to probe the internal structure and investigate more detailed information of the$\\delta$Scuti star HD 50844 with asteroseismology. Methods. We analyse the observed frequencies of the$\\delta$Scuti star HD 50844 obtained by Balona (2014), and search for possible multiplets based on the rotational splitting law of g-mode. We tried to disentangle the frequency spectra of HD 50844 by means of the rotational splitting only. We then compare them with theoretical pulsation modes, which correspond to stellar evolutionary models with various sets of initial metallicity and stellar mass, to find the best-fitting model. Results. There are three multiplets including two complete triplets and one incomplete quintuplet, in which mode identifications for spherical harmonic degree$l$and azimuthal number$m$are unique. The corresponding rotational period of HD 50844 is found to be 2.44$^{+0.13}_{-0.08}$days. The physical parameters of HD 50844 are well limited in a small region by three modes identified as... 1. A Substellar Companion to the Dusty Pleiades Star HD 23514 CERN Document Server Rodriguez, David R; Zuckerman, B; Macintosh, Bruce; Melis, Carl 2011-01-01 With adaptive optics imaging at Keck observatory, we have discovered a substellar companion to the F6 Pleiades star HD 23514, one of the dustiest main-sequence stars known to date (L_{IR}/L_{*}~2%). This is one of the first brown dwarfs discovered as a companion to a star in the Pleiades. The 0.06 M$_\\odot$late-M secondary has a projected separation of ~360 AU. The scarcity of substellar companions to stellar primaries in the Pleiades combined with the extremely dusty environment make this a unique system to study. 2. Helium stratification in HD 145792: a new Helium strong star OpenAIRE Catanzaro, G 2007-01-01 In this paper we report on the real nature of the star HD 145792, classified as He weak in {\\it The General Catalogue of Ap and Am stars''}. By means of high resolution spectroscopic data, we refined the atmospheric parameters of the star, obtaining: T$_{\\rm eff}$= 14400$\\pm$400 K,$\\log g$= 4.06$\\pm$0.08 and$\\xi$= 0$^{+0.6}$km s$^{-1}$. These values resulted always lower than those derived by different authors with pure photometric approaches. Using our values we u... 3. CHARACTERIZING THE RIGIDLY ROTATING MAGNETOSPHERE STARS HD 345439 AND HD 23478 Energy Technology Data Exchange (ETDEWEB) Wisniewski, J. P.; Lomax, J. R. [Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, 440 W. Brooks Street, Norman, OK 73019 (United States); Chojnowski, S. D. [Department of Astronomy, New Mexico State University, 1780 E University Avenue, Las Cruces, NM 88003 (United States); Davenport, J. R. A. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Bartz, J.; Pepper, J. [Lehigh University, Department of Physics, 413 Deming Lewis Lab, 16 Memorial Drive, East Bethlehem, PA 18015 (United States); Whelan, D. G. [Department of Physics, Austin College, 900 N. Grand Avenue, Sherman, TX 75090 (United States); Eikenberry, S. S. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Majewski, S. R.; Skrutskie, M. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States); Richardson, N. D., E-mail: wisniewski@ou.edu [Département de Physique and Centre de Recherche en Astrophysique du Québec (CRAQ), Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada) 2015-10-01 The SDSS III APOGEE survey recently identified two new σ Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the Kilodegree Extremely Little Telescope, Wide Angle Search for Planets, and ASAS surveys reveals the presence of a ∼0.7701 day period in each data set, suggesting the system is among the faster known σ Ori E analogs. We also see clear evidence that the strength of Hα, H i Brackett series lines, and He i lines also vary on a ∼0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5 m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H i lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H i Br-11 line strength and line profile in multi-epoch observations of HD 23478 from the SDSS-III APOGEE instrument. The observed periodic behavior is consistent with that recently reported by Sikora and collaborators in optical spectra. 4. Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars and stars with debris disks CERN Document Server Hubrig, S; Schöller, M; Grady, C; Schuetz, O; Pogodin, M A; Cure, M; Hamaguchi, K; Yudin, R V 2009-01-01 Among the 21 Herbig Ae/Be stars studied, new detections of a magnetic field were achieved in six stars. For three Herbig Ae/Be stars, we confirm previous magnetic field detections. The largest longitudinal magnetic field, = -454+-42G, was detected in the Herbig Ae/Be star HD101412 using hydrogen lines. No field detection at a significance level of 3sigma was achieved in stars with debris disks. Our study does not indicate any correlation of the strength of the longitudinal magnetic field with disk orientation, disk geometry, or the presence of a companion. We also do not see any simple dependence on the mass-accretion rate. However, it is likely that the range of observed field values qualitatively supports the expectations from magnetospheric accretion models giving support for dipole-like field geometries. Both the magnetic field strength and the X-ray emission show hints for a decline with age in the range of ~2-14Myrs probed by our sample supporting a dynamo mechanism that decays with age. However, our s... 5. Optical Mass Flow Diagnostics in Herbig Ae/Be Stars CERN Document Server Cauley, P Wilson 2015-01-01 We examine a broad range of mass flow diagnostics in a large sample of Herbig Ae/Be stars (HAEBES) using high resolution optical spectra. The H-beta and He I 5876 angstrom lines show the highest incidence of P-Cygni (30%) and inverse P-Cygni (14%) morphologies, respectively. The Fe II 4924 angstrom line also shows a large incidence of P-Cygni profiles (11%). We find support for many of the conclusions reached in a study based on the analysis of the He I 10830 angstrom line in a large sample of HAEBES. Namely, HAEBES exhibit smaller fractions of both blue-shifted absorption (i.e. mass outflow) and red-shifted absorption (i.e. mass infall or accretion) than their lower mass cousins, the classical T Tauri stars (CTTSs). In particular, the optical data supports the conclusion that HAEBES displaying red-shifted absorption, in general, show maximum red-shifted absorption velocities that are smaller fractions of their stellar escape velocities than is found for CTTSs. This suggests that HAEBE accretion flows are ori... 6. A spectroscopic analysis of the chemically peculiar star HD207561 CERN Document Server Joshi, S; Martinez, P; Sachkov, M; Joshi, Y C; Seetha, S; Chakradhari, N K; Mary, D L; Girish, V; Ashoka, B N 2012-01-01 In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is s... 7. Magnetic Doppler imaging of the chemically peculiar star HD 125248 Science.gov (United States) Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Ilyin, I. 2016-04-01 Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars. Aims: We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. Methods: We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the help of magnetic Doppler imaging techniques and model atmospheres taking the effects of strong magnetic fields and nonsolar chemical composition into account. Results: We improved the atmospheric parameters of the star, Teff = 9850 ± 250 K and log g = 4.05 ± 0.10. We performed detailed abundance analysis, which confirmed that HD 125248 has abundances typical of other Ap stars, and discovered significant vertical stratification effects for the Fe ii and Cr ii ions. We computed LSD Stokes profiles using several line masks corresponding to Fe-peak and rare earth elements, and studied their behavior with rotational phase. Combining previous longitudinal field measurements with our own observations, we improved the rotational period of the star Prot = 9.29558 ± 0.00006 d. Magnetic Doppler imaging of HD 125248 showed that its magnetic field is mostly poloidal and quasi-dipolar with two large spots of different polarity and field strength. The chemical maps of Fe, Cr, Ce, Nd, Gd, and Ti show abundance contrasts of 0.9-3.5 dex. Among these elements, the Fe abundance map does not show high-contrast features. Cr is overabundant around the negative magnetic pole and has 3.5 dex abundance range. The rare earth elements and Ti are overabundant near the positive magnetic pole. Conclusions: The magnetic field of HD 125248 has strong deviations from the classical oblique dipole field 8. Chemical Abundances of the magnetic CP star HD 168733 Science.gov (United States) Collado, A.; López-García, Z. 2009-04-01 A detailed abundance analysis has been carried out for the magnetic CP star HD 168733 using high-resolution spectra obtained with the EBASIM echelle spectrograph at the 2.1 m CASLEO telescope in Argentina. The spectral coverage is 382-700 nm. It is neither a silicon nor a mercury-manganese star. Compared to the Sun, C and N are slightly overabundant, while Mg and S are deficient, Si is normal and P and Cl are overabundant. The iron peak elements Sc, Ti, Cr and Fe are overabundant. Lines of Ti III and Fe III are also identified. HD 168733 shows a great overabundance of Ga, Sr, Y, Zr, Xe, Pt, Hg and of some rare earths. 9. HD 98618: A Star Closely Resembling our Sun CERN Document Server Melendez, J; Robles, J A; Dodds-Eden, Katie; Melendez, Jorge; Observatory, RSAA/Mt Stromlo 2006-01-01 Despite the observational effort carried out in the last few decades, no perfect solar twin has been found to date. An important milestone was achieved a decade ago by Porto de Mello & da Silva, who showed that 18 Sco is almost a solar twin. In the present work, we use extremely high resolution (R = 10^5) high S/N Keck HIRES spectra to carry out a differential analysis of sixteen solar twin candidates. We show that HD 98618 is the second closest solar twin, and that the fundamental parameters of both HD 98618 and 18 Sco are very similar (within a few percent) to the host star of our solar system, including the likelihood of hosting a terrestrial planet within their habitable zone. We suggest that these stars should be given top priority in exoplanet and SETI surveys. 10. Characterizing the Rigidly Rotating Magnetosphere Stars HD 345439 and HD 23478 CERN Document Server Wisniewski, J P; Davenport, J R A; Bartz, J; Pepper, J; Whelan, D G; Eikenberry, S S; Lomax, J R; Majewski, S R; Richardson, N D; Skrutskie, M 2015-01-01 The SDSS III APOGEE survey recently identified two new$\\sigma$Ori E type candidates, HD 345439 and HD 23478, which are a rare subset of rapidly rotating massive stars whose large (kGauss) magnetic fields confine circumstellar material around these systems. Our analysis of multi-epoch photometric observations of HD 345439 from the KELT, SuperWASP, and ASAS surveys reveals the presence of a$\\sim$0.7701 day period in each dataset, suggesting the system is amongst the faster known$\\sigma$Ori E analogs. We also see clear evidence that the strength of H-alpha, H I Brackett series lines, and He I lines also vary on a$\\sim$0.7701 day period from our analysis of multi-epoch, multi-wavelength spectroscopic monitoring of the system from the APO 3.5m telescope. We trace the evolution of select emission line profiles in the system, and observe coherent line profile variability in both optical and infrared H I lines, as expected for rigidly rotating magnetosphere stars. We also analyze the evolution of the H I Br-11 ... 11. CNO and F abundances in the barium star HD 123396 CERN Document Server Alves-Brito, Alan; Yong, David; Meléndez, Jorge; Vásquez, Sergio 2011-01-01 [Abridged] Barium stars are moderately rare chemically peculiar objects which are believed to be the result of the pollution of an otherwise normal star by material from an evolved companion on the asymptotic giant branch (AGB). We aim to derive carbon, nitrogen, oxygen, and fluorine abundances for the first time from infrared spectra of the barium red giant star HD 123396 to quantitatively test AGB nucleosynthesis models for producing barium stars via mass accretion. High-resolution and high S/N infrared spectra were obtained using the Phoenix spectrograph mounted at the Gemini South telescope. The abundances were obtained through spectrum synthesis of individual atomic and molecular lines, using the MOOG stellar line analysis program together with Kurucz's stellar atmosphere models. The analysis was classical, using 1D stellar models and spectral synthesis under the assumption of local thermodynamic equilibrium. We confirm that HD 123396 is a metal-deficient barium star ([Fe/H] = -1.05), with A(C) = 7.88, A... 12. An Analysis of the Rapidly Rotating Bp star HD 133880 Science.gov (United States) Bailey, J. D.; Grunhut, J.; Shultz, M.; Wade, G.; Landstreet, J. D.; Bohlender, D.; Lim, J.; Wong, K.; Drake, S.; Linsky, J. 2012-01-01 HD 133880 is a rapidly rotating chemically peculiar B-type (Bp) star (nu sin i approx = 103km/s) and is host to one of the strongest magnetic fields of any Ap/Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. 12 new spectra, four of which are polarimetric, obtained from the FEROS, ESPaDOnS and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of He, O, Mg, Si, Ti. Cr, Fe, Ni, Pr and Nd. An abundance analysis was carried out using ZEEMAN, a program which synthesizes spectral line profiles for stars with permeating magnetic fields. The magnetic field structure was characterized by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. Both magnetic hemispheres are clearly visible during the stellar rotation, and thus a three-ring abundance distribution model encompassing both magnetic poles and magnetic equator with equal spans in colatitude was adopted. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P = 0.877 476 +/- 0.000009 d. Our simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe and Pr. All elements; except Mg, are overabundant compared to the Son. Mg appears to be approximately uniform over the stellar surface, while all other elements are more abundant in the negative magnetic hemisphere than in the positive magnetic hemisphere. In contrast to most Ap/Bp stars which show an underabundance in 0, in HD 133880 this element is clearly overabundant compared to the solar abundance ratio. In studying the Ha and Paschen lines in the optical spectra, we could not 13. Magnetic Doppler imaging of the chemically peculiar star HD 125248 CERN Document Server Rusomarov, N; Ryabchikova, T; Ilyin, I 2016-01-01 Intermediate-mass, chemically peculiar stars with strong magnetic fields give us an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in their atmospheres. We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the magnetic Doppler imaging technique. We improved the atmospheric parameters of the star, T_eff = 9850K +/- 250K and logg = 4.05 +/- 0.10. We performed detailed abundance analysis and discovered vertical stratification effects for the FeII and CrII ions. We computed LSD Stokes profiles and studied their behavior with rotational phase. We improved the rotational period of the star P_rot = 9.29558(6)d. Magnetic Doppler imaging of HD 125248 showed that its magn... 14. An M-dwarf star in the transition disk of Herbig HD142527; Physical parameters and orbital elements CERN Document Server Lacour, S; Cheetham, A; Greenbaum, A; Pearce, T; Marino, S; Tuthill, P; Pueyo, L; Mamajek, E E; Girard, J H; Sivaramakrishnan, A; Bonnefoy, M; Baraffe, I; Chauvin, G; Olofsson, J; Juhasz, A; Benisty, M; Pott, J -U; Sicilia-Aguilar, A; Henning, T; Cardwell, A; Goodsell, S; Graham, J R; Hibon, P; Ingraham, P; Konopacky, Q; Macintosh, B; Oppenheimer, R; Perrin, M; Rantakyrö, F; Sadakuni, N; Thomas, S 2015-01-01 HD 142527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of$\\approx20$in mass ratio between the two objects makes this binary system different from any other YSO. The HD142527 system could therefore provides a valuable testbed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and the dust trapping observed by ALMA at longer distances. We have observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present here the SEDS for HD 142527A and B from the$R$band up to the$Mband as well as the orbital motion of HD 142527B ov... 15. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ? OpenAIRE Alecian, E.; Neiner, C.; Mathis, S.; Catala, C.; Kochukhov, O.; Landstreet, J.; collaboration, the MiMeS 2013-01-01 In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman ... 16. Doppler-Zeeman mapping of magnetic CP stars The case of the CP star HD 215441 CERN Document Server Khokhlova, V L; Stepanov, V V; Tsymbal, V V 1998-01-01 The recently developed method of Doppler-Zeeman mapping of magnetic CP stars (Vasilchenko et al.,1996, hereafter referenced as V.S.K., and also the contribution to this volume) confirmed its efficiency and robustness not only for model tests but also in the case of a real star. The method was used for mapping Babcock's star HD 215441, wich has the strongest known magnetic field and resolved Zeeman components in the lines of its spectra. 17. Evidence for Magnetic Star-Planet Interactions in HD 189733 Science.gov (United States) Wolk, S. J.; Pillitteri, I.; Kashyap, V.; Cohen, O.; Lisse, C.; Knutson, H. A. 2011-12-01 We report on XMM-Newton observations of the planetary host star HD 189733. The system has a close in planet and it can potentially affect the coronal structure via interactions with the magnetosphere. During the 2009 secondary eclipse we observed a softening of the X-ray spectrum significant at level of ˜3σ. Further, we observed the most intense flare recorded at either epochs. This flare occurred 3 ks after the end of the eclipse. The flare decay shows several minor ignitions perhaps linked to the main event and hinting for secondary loops that emit triggered by the main loop. Magneto-Hydro-Dynamical (MHD) simulations show that the magnetic interaction between planet and star enhances the density and the magnetic field in a region comprised between the planet and the star because of their relative orbital/rotation motion. 18. The evidence for clumpy accretion in the Herbig Ae star HR 5999 Science.gov (United States) Perez, M. R.; Grady, C. A.; The, P. S. 1994-01-01 Analysis of IUE high- and low-dispersion spectra of the young Herbig Ae star HR 5999 (HD 144668) covering 1978-1992 has revealed dramatic changes in the Mg II h and k (2795.5, 2802.7 A) emission profiles, changes in the column density and distribution in radial velocity of accreting gas, and flux in the Ly(alpha), O I and C IV emission lines, which are correlated with the UV excess luminosity. We also observe variability in the spectral type inferred from the UV spectral energy distribution, ranging from A5 IV-III in high state to A7 III in the low state. The trend of earlier inferred spectral type with decreasing wavelength and with increasing UV continuum flux has previously been noted as a signature of accretion disks in lower mass pre-main sequence stars (PMS) and in systems undergoing FU Orionis-type outbursts. Our data represent the first detection of similar phenomena in an intermediate mass (M equal to or greater than 2 solar mass) PMS star. Recent IUE spectra show gas accreting toward the star with velocities as high as +300 km/s, much as is seen toward beta Pic, and suggest that we also view this system through the debris disk. The absence of UV lines with the rotational broadening expected given the optical data (A7 IV, upsilon sin i = 180 plus or minus 20 km/s) for this system also suggests that most of the UV light originates in the disk, even in the low continuum state. The dramatic variability in the column density of accreting gas, consistent with clumpy accretion, such as has been observed toward beta Pic, is a hallmark of accretion onto young stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars, and is not restricted to the clearing phase, since detectable amounts of accretion are present for stars with 0.5 less than t(sub age) less than 2.8 Myr. The implications for models of beta Pic and similar systems are briefly discussed. 19. An Analysis of the Rapidly Rotating Bp Star HD 133880 CERN Document Server Bailey, J D; Shultz, M; Wade, G; Landstreet, J D; Bohlender, D; Lim, J; Wong, K; Drake, S; Linsky, J 2012-01-01 HD 133880 is a rapidly rotating Bp star and host to one of the strongest magnetic fields of any Bp star. A member of the Upper Centaurus Lupus association, it is a star with a well-determined age of 16 Myr. Twelve new spectra obtained from the FEROS, ESPaDOnS, and HARPS instruments, provide sufficient material from which to re-evaluate the magnetic field and obtain a first approximation to the atmospheric abundance distributions of various elements. Using the new magnetic field measurements and optical photometry together with previously published data, we refine the period of HD 133880 to P = 0.877476 \\pm 0.000009 days. The magnetic field structure was characterised by a colinear multipole expansion from the observed variations of the longitudinal and surface fields with rotational phase. This simple axisymmetric magnetic field model is based on a predominantly quadrupolar component that roughly describes the field variations. Using spectrum synthesis, we derived mean abundances for O, Mg, Si, Ti, Cr, Fe, Nd... 20. The CP Galium Stars in the UV. I. HD 168733 Science.gov (United States) Collado, A.; López García, Z.; Levato, H.; Malaroda, S. HD 168733 is a magnetic CP star with an unusual spectrum. It was not possible to assign this star to the Si or HgMn group. Jaschek & Jaschek (A&A, 171, 380, 1987) have included this star in a list of objects having strong UV Gallium lines. In order to get some clues about the real nature of this star, we are performing an elemental abundance analysis of this star using spectrograms obtained with EBASIM spectrograph attached to CASLEO 2.15 m telescope. The reduction of the observational material and the measurements of the equivalent widths were carried out using the appropriate IRAF tasks. The atmospheric parameters Teff and log g were determined using uvbybeta photometry and TemLogG code with the corrections suggested by Adelman & Rayle (A&A 447, 685, 2000) for magnetic CP stars. The adopted values are: Teff = 13274 K, log g = 3.58. The chemical abundances are being calculating using WIDTH9 code. 1. Chemical abundances of the high-latitude Herbig Ae Star PDS2 CERN Document Server Cowley, C R; Przybilla, N 2014-01-01 The Herbig Ae star PDS2 (CD -53 251) is unusual in several ways. It has a high Galactic latitude, unrelated to any known star-forming region. It is at the cool end of the Herbig Ae sequence, where favorable circumstances facilitate the determination of stellar parameters and chemical abundances. We findT_{\\rm eff} = 6500$K, and$\\log(g) = 3.5$. The relatively low$v\\cdot\\sin(i) = 12\\pm2$\\kms made it possible to use mostly weak lines for the abundances. PDS2 appears to belong to the class of Herbig Ae stars with normal volatile and depleted involatile elements. This pattern is seen not only in$\\lambda$Boo stars, but in some post AGB and RV Tauri stars. The appearance of the same abundance pattern in young stars and highly evolved giants strengthens the hypothesis of gas-grain separation for its origin. The intermediate volatile zinc can violate the pattern of depleted volatiles. 2. HARPS spectropolarimetry of three sharp-lined Herbig Ae stars: New insights OpenAIRE Järvinen, S. P.; Carroll, T. A.; Hubrig, S.; Schöller, M; Ilyin, I; Korhonen, H.; Pogodin, M.; Drake, N.A 2015-01-01 Several arguments have been presented that favour a scenario in which the low detection rate of magnetic fields in Herbig Ae stars can be explained by the weakness of these fields and rather large measurement uncertainties. Spectropolarimetric studies involving sharp-lined Herbig Ae stars appear to be promising for the detection of such weak magnetic fields. These studies offer a clear spectrum interpretation with respect to the effects of blending, local velocity fields, and chemical abundan... 3. Far-ultraviolet energy distributions of the metal-poor A stars HD 109995 and HD 161817 Science.gov (United States) Boehm-Vitense, E. 1981-01-01 Low-resolution IUE spectra at wavelengths between 1300 and 3400 A of the metal-poor stars HD 109995 (A1p) and HD 161817 (A4p) have been compared with model-atmosphere energy distributions computed by Kurucz (1979). Good overall agreement is found. Effective temperatures, metal abundances, and angular diameters could be determined. Assuming an absolute visual magnitude of 0.7, the previously determined gravity log = 3 yields masses of 0.5 solar masses for both stars. It is found that the theoretical UBV colors calculated earlier agree reaonably well with the ones observed for these stars. 4. Magnetic Doppler Imaging of He-strong star HD 184927 CERN Document Server Yakunin, I; Bohlender, D; Kochukhov, O; Tsymbal, V 2013-01-01 We have employed an extensive new timeseries of Stokes I and V spectra obtained with the ESPaDOnS spectropolarimeter at the 3.6-m Canada-France-Hawaii Telescope to investigate the physical parameters, chemical abundance distributions and magnetic field topology of the slowly-rotating He-strong star HD 184927. We infer a rotation period of 9.53071+-0.00120 from H-alpha, H-beta, LSD magnetic measurements and EWs of helium lines. We used an extensive NLTE TLUSTY grid along with the SYNSPEC code to model the observed spectra and find a new value of luminosity. In this poster we present the derived physical parameters of the star and the results of Magnetic Doppler Imaging analysis of the Stokes I and V profiles. Wide wings of helium lines can be described only under the assumption of the presence of a large, very helium-rich spot. 5. Accurate radio and optical positions for the radio star HD 36705 (AB Doradus) Science.gov (United States) White, Graeme L.; Jauncey, David L.; Batty, Michael J.; Peters, W. L.; Gulkis, S. 1988-01-01 Arc-second position measurements of the active star HD 36705 (AB Dor) and of the variable radio source found nearby are presented. These measurements show that the radio source is clearly identified with HD 36705 and not with the nearby red-dwarf star Rst 137B. 6. Characterisation of the magnetic fields of the Herbig Be stars HD 200775 and V380 0ri CERN Document Server Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J C; Donati, J F; Folsom, C P; Landstreet, J D; Silvester, J 2006-01-01 The origin of the magnetic fields of the chemically peculiar main sequence Ap/Bp stars is still matter of intense debate. The recent discoveries of magnetic fields in Herbig Ae/Be stars using high resolution data obtained with the spectropolarimeter ESPaDOnS at CFHT provide a strong argument in favour of the fossil field hypothesis. Using a simple oblique rotator model of a centered dipole, we fit the Stokes V LSD profiles of two of these magnetic HAeBe stars, HD 200775 and V380 Ori, as well as their variations on timescales from days to months. We find that in both cases the dipole hypothesis is acceptable and we determine the rotation period, the angle between rotation and magnetic axes and the intensity of the magnetic field at pole. 7. Warm H2O and OH in the disk around the Herbig star HD 163296 CERN Document Server Fedele, D; van Dishoeck, E F; Herczeg, G J; Evans, N J; Bouwman, J; Henning, Th; Green, J 2012-01-01 We present observations of far-infrared (50-200 micron) OH and H2O emission of the disk around the Herbig Ae star HD 163296 obtained with Herschel/PACS in the context of the DIGIT key program. In addition to strong [OI] emission, a number of OH doublets and a few weak highly excited lines of H2O are detected. The presence of warm H2O in this Herbig disk is confirmed by a line stacking analysis, enabled by the full PACS spectral scan, and by lines seen in Spitzer data. The line fluxes are analyzed using an LTE slab model including line opacity. The water column density is 10^14 - 10^15 cm^-2, and the excitation temperature is 200-300 K implying warm gas with a density n > 10^5 cm^-3. For OH we find a column density of 10^14 - 2x10^15 cm^-2 and T_ex ~ 300-500 K. For both species we find an emitting region of r ~ 15-20 AU from the star. We argue that the molecular emission arises from the protoplanetary disk rather than from an outflow. This far-infrared detection of both H2O and OH contrasts with near- and mid-... 8. The Physical Parameters of the Retired A Star HD185351 CERN Document Server Johnson, John Asher; Boyajian, Tabetha; Brewer, John M; White, Timothy R; von Braun, Kaspar; Maestro, Vicente; Stello, Dennis; Barclay, Thomas 2014-01-01 We report here an analysis of the physical stellar parameters of the giant star HD185351 using Kepler short-cadence photometry, optical and near infrared interferometry from CHARA, and high-resolution spectroscopy. Asteroseismic oscillations detected in the Kepler short-cadence photometry combined with an effective temperature calculated from the interferometric angular diameter and bolometric flux yield a mean density, rho_star = 0.0130 +- 0.0003 rho_sun and surface gravity, logg = 3.280 +- 0.011. Combining the gravity and density we find Rstar = 5.35 +- 0.20 Rsun and Mstar = 1.99 +- 0.23 Msun. The trigonometric parallax and CHARA angular diameter give a radius Rstar = 4.97 +- 0.07 Rsun. This smaller radius,when combined with the mean stellar density, corresponds to a stellar mass Mstar = 1.60 +- 0.08 Msun, which is smaller than the asteroseismic mass by 1.6-sigma. We find that a larger mass is supported by the observation of mixed modes in our high-precision photometry, the spacing of which is consistent on... 9. DUST EVOLUTION IN PROTOPLANETARY DISKS AROUND HERBIG Ae/Be STARS-THE SPITZER VIEW NARCIS (Netherlands) Juhasz, A.; Bouwman, J.; Henning, Th.; Acke, B.; van den Ancker, M. E.; Meeus, G.; Dominik, C.; Min, M.; Tielens, A. G. G. M.; Waters, L. B. F. M. 2010-01-01 In this paper, we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validi 10. Discovery of the longest-period rapidly oscillating Ap star HD177765 CERN Document Server Alentiev, D; Ryabchikova, T; Cunha, M; Tsymbal, V; Weiss, W 2011-01-01 We present the discovery of a long-period, rapidly oscillating Ap star, HD177765. Using high-resolution time-series observations obtained with UVES at the ESO VLT telescope, we found radial velocity variations with amplitudes 7-150 m/s and a period of 23.6 min, exceeding that of any previously known roAp star. The largest pulsation amplitudes are observed for Eu III, Ce III and for the narrow core of Halpha. We derived the atmospheric parameters and chemical composition of HD177765, showing this star to be similar to other long-period roAp stars. Comparison with theoretical pulsational models indicates an advanced evolutionary state for HD177765. Abundance analyses of this and other roAp stars suggest a systematic variation with age of the rare-earth line anomalies seen in cool Ap stars. 11. Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra Science.gov (United States) Tanrıverdi, T.; Baştürk, Ö. 2016-08-01 This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD 80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003)1 12. The magnetic field topology and chemical abundance distributions of the Ap star HD 32633 OpenAIRE Silvester, James; Kochukhov, Oleg; Wade, G. A. 2015-01-01 Previous observations of the Ap star HD 32633 indicated that its magnetic field was unusually complex in nature and could not be characterised by a simple dipolar structure. Here we derive magnetic field maps and chemical abundance distributions for this star using full Stokes vector (Stokes$IQUV$) high-resolution observations obtained with the ESPaDOnS and Narval spectropolarimeters. Our maps, produced using the Invers10 magnetic Doppler imaging (MDI) code, show that HD 32633 has a strong m... 13. An M-dwarf star in the transition disk of Herbig HD 142527. Physical parameters and orbital elements Science.gov (United States) Lacour, S.; Biller, B.; Cheetham, A.; Greenbaum, A.; Pearce, T.; Marino, S.; Tuthill, P.; Pueyo, L.; Mamajek, E. E.; Girard, J. H.; Sivaramakrishnan, A.; Bonnefoy, M.; Baraffe, I.; Chauvin, G.; Olofsson, J.; Juhasz, A.; Benisty, M.; Pott, J.-U.; Sicilia-Aguilar, A.; Henning, T.; Cardwell, A.; Goodsell, S.; Graham, J. R.; Hibon, P.; Ingraham, P.; Konopacky, Q.; Macintosh, B.; Oppenheimer, R.; Perrin, M.; Rantakyrö, F.; Sadakuni, N.; Thomas, S. 2016-05-01 Aims: HD 42527A is one of the most studied Herbig Ae/Be stars with a transitional disk, as it has the largest imaged gap in any protoplanetary disk: the gas is cleared from 30 to 90 AU. The HD 142527 system is also unique in that it has a stellar companion with a small mass compared to the mass of the primary star. This factor of ≈20 in mass ratio between the two objects makes this binary system different from any other YSO. The HD 142527 system could therefore provide a valuable test bed for understanding the impact of a lower mass companion on disk structure. This low-mass stellar object may be responsible for both the gap and dust trapping observed by ALMA at longer distances. Methods: We observed this system with the NACO and GPI instruments using the aperture masking technique. Aperture masking is ideal for providing high dynamic range even at very small angular separations. We present the spectral energy distribution (SED) for HD 142527A and B. Brightness of the companion is now known from the R band up to the M' band. We also followed the orbital motion of HD 142527B over a period of more than two years. Results: The SED of the companion is compatible with a T = 3000 ± 100 K object in addition to a 1700 K blackbody environment (likely a circum-secondary disk). From evolution models, we find that it is compatible with an object of mass 0.13 ± 0.03 M⊙, radius 0.90 ± 0.15 R⊙, and age Myr. This age is significantly younger than the age previously estimated for HD 142527A. Computations to constrain the orbital parameters found a semimajor axis of mas, an eccentricity of 0.5 ± 0.2, an inclination of 125 ± 15 degrees, and a position angle of the right ascending node of -5 ± 40 degrees. Inclination and position angle of the ascending node are in agreement with an orbit coplanar with the inner disk, not coplanar with the outer disk. Despite its high eccentricity, it is unlikely that HD 142527B is responsible for truncating the inner edge of the outer disk. 14. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380 Institute of Scientific and Technical Information of China (English) Blesson Mathew; D. P. K. Banerjee; N. M. Ashok; Annapurni Subramaniam; Bhaskaran Bhavya; Vishal Joshi 2012-01-01 We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain.This object,which is a member of the young cluster NGC 7380,has been variously proposed to be a Be star,a D-type symbiotic and a Herbig Ae/Be star in separate studies.Here we present optical spectroscopy,near-IR photometry and narrow band Hα imaging of the nebulosity in its environment.Analysis of all these results,including the spectral energy distribution constructed from available data,strongly indicate the source to be a Herbig Ae/Be star.The star is found to be accompanied by a nebulosity with an interesting structure.A bow-shock shaped structure,similar to a cometary nebula,is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e.the star DH Cep).An interesting spectroscopic finding,from the forbidden [SⅡ] 6716,6731 (A) and [OI] 6300 (A) lines,is the detection of a blue-shifted high velocity outflow (200 ±50 km s- 1) from the star. 15. ALMA detection of the rotating molecular disk wind drom the young star HD 163296 CERN Document Server Klaassen, P D; Mathews, G S; De Gregorio-Monsalvo, J C Mottram I; van Dishoeck, E F; Takahashi, S; Akiyama, E; Chapillon, E; Espada, D; Hales, A; Hogerheijde, M R; Rawlings, M; Schmalzl, M; Testi, L 2013-01-01 Disk winds have been postulated as a mechanism for angular momentum release in protostellar systems for decades. HD 163296 is a Herbig Ae star surrounded by a disk and has been shown to host a series of HH knots (HH 409) with bow shocks associated with the farthest knots. Here we present ALMA Science Verification data of CO J=2-1 and J=3-2 emission which are spatially coincident with the blue shifted jet of HH knots, and offset from the disk by -18.6 km/s. The emission has a double corkscrew morphology and extends more than 10" from the disk with embedded emission clumps coincident with jet knots. We interpret this double corkscrew as emission from material in a molecular disk wind, and that the compact emission near the jet knots is being heated by the jet which is moving at much higher velocities. We show that the J=3-2 emission is likely heavily filtered by the interferometer, but the J=2-1 emission suffers less due to the larger beam and measurable angular scales. Excitation analysis suggests temperatures... 16. How non-magnetic are "non-magnetic" Herbig Ae/Be stars? CERN Document Server Wade, G A; Catala, C; Bagnulo, S; Landstreet, J D; Flood, J; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Silvester, J 2007-01-01 Our recent discovery of magnetic fields in a small number of Herbig Ae/Be stars has required that we survey a much larger sample of stars. From our FORS1 and ESPaDOnS surveys, we have acquired about 125 observations of some 70 stars in which no magnetic fields are detected. Using a Monte Carlo approach, we have performed statistical comparisons of the observed longitudinal fields and LSD Stokes V profiles of these apparently non-magnetic stars with a variety of field models. This has allowed us to derive general upper limits on the presence of dipolar fields in the sample, and to place realistic upper limits on undetected dipole fields which may be present in individual stars. This paper briefly reports the results of the statistical modeling, as well as field upper limits for individual stars of particular interest. 17. The prevalence of weak magnetic fields in Herbig Ae stars: The case of PDS2 CERN Document Server Hubrig, S; Schöller, M; Ilyin, I 2015-01-01 Models of magnetically driven accretion and outflows reproduce many observational properties of T Tauri stars, but the picture is much less clear for the Herbig Ae/Be stars, due to the poor knowledge of their magnetic field strength and topology. The Herbig Ae star PDS2 was previously included in two magnetic studies based on low-resolution spectropolarimetric observations. Only in one of these studies the presence of a weak mean longitudinal magnetic field was reported. In the present study, for the first time, high-resolution HARPS spectropolarimetric observations of PDS2 are used to investigate the presence of a magnetic field. A firm detection of a weak longitudinal magnetic field is achieved using the multi-line singular value decomposition method for Stokes profile reconstruction (=33+-5G). To gain better knowledge of typical magnetic field strengths in late Herbig Be and Herbig Ae stars, we compiled previous magnetic field measurements, revealing that only very few stars have fields stronger than 200G,... 18. Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra CERN Document Server Tanrıverdi, Taner 2015-01-01 This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003) were analysed to compute their elemental abundances using ATLAS9 (Kurucz, 1993, 2005; Sbordone et al., 2004). In our analysis we assumed local thermodynamic equilibrium. The atmospheric parameters of HD 80057 used in this study are from Firnstein & Przybilla (2012), and that of HD80404 are derived from spectral energy distribution, ionization equilibria of Cr I/II and Fe I/II, and the fits to the wings of Balmer lines and Paschen lines as Teff = 7700 +/- 150 K and log g=1.60 +/- 0.15 (in cgs). The microturbulent velocities of HD 80057 and HD 80404 have been determined as 4.3 +/- 0.1 and 2.2 +/- 0.7 km s^-1 . The rotational velocities are 15 +/-1 and 7 +/- 2 km s^-1 and their macroturbulence velocities are 24 +/-2 and 2+/-1 km s^-1 . We have given the abundances... 19. Studies of a possible new Herbig Ae/Be star in the open cluster NGC 7380 CERN Document Server Mathew, Blesson; Ashok, N M; Subramaniam, Annapurni; Bhavya, B; Joshi, Vishal 2012-01-01 We present a study of the star 2MASS J22472238+5801214 with the aim of identifying its true nature which has hitherto been uncertain. This object, which is a member of the young cluster NGC 7380, has been variously proposed to be a Be star, a D-type symbiotic and a Herbig Ae/Be star in separate studies. Here we present optical spectroscopy, near-IR photometry and narrow band H-alpha imaging of the nebulosity in its environment. Analysis of all these results, including the spectral energy distribution constructed from available data, strongly indicate the source to be a Herbig Ae/Be star. The star is found to be accompanied by a nebulosity with an interesting structure. A bow shock shaped structure, similar to a cometary nebula, is seen very close to the star with its apex oriented towards the photoionizing source of this region (i.e. the star DH Cep). An interesting spectroscopic finding, from the forbidden [SII] 6716, 6731 \\AA and [OI] 6300 \\AA lines, is the detection of a blue-shifted high velocity outflow ... 20. Einstein X-ray observations of Herbig Ae/Be stars Science.gov (United States) Damiani, F.; Micela, G.; Sciortino, S.; Harnden, F. R., Jr. 1994-01-01 We have investigated the X-ray emission from Herbig Ae/Be stars, using the full set of Einstein Imaging Proportional Counter (IPC) observations. Of a total of 31 observed Herbig stars, 11 are confidently identified with X-ray sources, with four additonal dubious identifications. We have used maximum likelihood luminosity functions to study the distribution of X-ray luminosity, and we find that Be stars are significantly brighter in X-rays than Ae stars and that their X-ray luminosity is independent of projected rotational velocity v sin i. The X-ray emission is instead correlated with stellar bolometric luminosity and with effective temperature, and also with the kinetic luminosity of the stellar wind. These results seem to exclude a solar-like origin for the X-ray emission, a possibility suggested by the most recent models of Herbig stars' structure, and suggest an analogy with the X-ray emission of O (and early B) stars. We also observe correlations between X-ray luminosity and the emission at 2.2 microns (K band) and 25 microns, which strengthen the case for X-ray emission of Herbig stars originating in their circumstellar envelopes. 1. The Chemical Compositions of Very Metal-Poor Stars HD 122563 and HD 140283; A View From the Infrared CERN Document Server Afşar, Melike; Frebel, Anna; Kim, Hwihyun; Mace, Gregory N; Kaplan, Kyle F; Lee, Hye-In; Oh, Hee-Young; Oh, Jae Sok; Pak, Soojong; Park, Chan; Pavel, Michael D; Yuk, In-Soo; Jaffe, Daniel T 2016-01-01 From high resolution (R = 45,000), high signal-to-noise (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = -3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to... 2. Evolution of the dust/gas environment around Herbig Ae/Be stars CERN Document Server Liu, Tie; Wu, Yuefang; Qin, Sheng-Li; Miller, Martin 2011-01-01 With the KOSMA 3-m telescope, 54 Herbig Ae/Be stars were surveyed in CO and$^{13}$CO emission lines. The properties of the stars and their circumstellar environments are studied by fitting the SEDs. The mean line width of$^{13}$CO (2-1) lines of this sample is 1.87 km s$^{-1}$. The average column density of H$_{2}$is found to be$4.9\\times10^{21}$cm$^{-2}$for the stars younger than$10^{6}$yr, while drops to$2.5\\times10^{21}$cm$^{-2}$for those older than$10^{6}$yr. No significant difference is found among the SEDs of Herbig Ae stars and Herbig Be stars at the same age. The infrared excess decreases with age. The envelope masses and the envelope accretion rates decease with age after$10^{5}$yr. The average disk mass of the sample is$3.3\\times10^{-2} M_{\\sun}. The disk accretion rate decreases more slowly than the envelope accretion rate. A strong correlation between the CO line intensity and the envelope mass is found. 3. Lithium and magnetic fields in giants. HD 232862 : a magnetic and lithium-rich giant star OpenAIRE Lèbre, A.; Palacios, A.; Nascimento Jr, J. D. do; Konstantinova-Antova, R.; Kolev, D.; Aurière, M.; de Laverny, P.; de Medeiros, J. R. 2009-01-01 We report the detection of an unusually high lithium content in HD 232862, a field giant classified as a G8II star, and hosting a magnetic field. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232862, KU Peg and HD 21018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also a... 4. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star? Science.gov (United States) Alecian, E.; Neiner, C.; Mathis, S.; Catala, C.; Kochukhov, O.; Landstreet, J. 2013-01-01 In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman signature on timescales of days to weeks, indicating that the configuration of its field has changed between 2009 and 2011. Such a sudden change of external structure of a fossil field has never previously been observed in any intermediate or high-mass star. HD 190073 is an almost entirely radiative pre-main sequence star, probably hosting a growing convective core. We propose that this dramatic change is the result of the interaction between the fossil field and the ignition of a dynamo field generated in the newly-born convective core. Based on observations collected at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers (INSU) of the Centre National de la Recherche Scientifique (CNRS) of France and the University of Hawaii, at the Observatoire du Pic du Midi (France), operated by INSU, and at the European Southern Observatory, Chile (Program ID 187.D-0917). 5. The dramatic change of the fossil magnetic field of HD 190073: evidence of the birth of the convective core in a Herbig star ? CERN Document Server Alecian, E; Mathis, S; Catala, C; Kochukhov, O; Landstreet, J 2013-01-01 In the context of the ESPaDOnS and Narval spectropolarimetric surveys of Herbig Ae/Be stars, we discovered and then monitored the magnetic field of HD 190073 over more than four years, from 2004 to 2009. Our observations all displayed similar Zeeman signatures in the Stokes V spectra, indicating that HD 190073 hosted an aligned dipole, stable over many years, consistent with a fossil origin. We obtained new observations of the star in 2011 and 2012 and detected clear variations of the Zeeman signature on timescales of days to weeks, indicating that the configuration of its field has changed between 2009 and 2011. Such a sudden change of external structure of a fossil field has never previously been observed in any intermediate or high-mass star. HD 190073 is an almost entirely radiative pre-main sequence star, probably hosting a growing convective core. We propose that this dramatic change is the result of the interaction between the fossil field and the ignition of a dynamo field generated in the newly-born ... 6. STEREO observations of HD90386 (RX Sex): a δ-Scuti or a hybrid star? Science.gov (United States) Ozuyar, D.; Stevens, I. R.; Whittaker, G.; Sangaralingam, V. 2016-04-01 HD90386 is a rarely studied bright A2V type δ Scuti star (V = 6.66 mag). It displays short-term light curve variations which are originated due to either a beating phenomenon or a non-periodic variation. In this paper, we presented high-precision photometric data of HD90386 taken by the STEREO satellite between 2007 and 2011 to shed light on its internal structure and evolution stage. From the frequency analysis of the four-year data, we detected that HD90386 had at least six different frequencies between 1 and 15 c d-1. The most dominant frequencies were found at around 10.25258 c d-1 (A ∼ 1.92 mmag) and 12.40076 c d-1 (A ∼ 0.61 mmag). Based on the ratio between these frequencies, the star was considered as an overtone pulsator. The variation in pulsation period over 35 years was calculated to be dP/Pdt = 5.39(2) x 10-3 yr-1. Other variabilities at around 1.0 c d-1 in the amplitude spectrum of HD90386 were also discussed. In order to explain these variabilities, possible rotational effects and γ Dor type variations were focused. Consequently, depending on the rotation velocity of HD90386, we speculated that these changes might be related to γ Dor type high-order g-modes shifted to the higher frequencies and that HD90386 might be a hybrid star. 7. Comparison between accretion-related properties of Herbig Ae/Be and T Tauri stars CERN Document Server Mendigutía, I 2013-01-01 This paper summarizes several results concerning the comparison between accretion-related properties of cool (T Tauri; T < 7000 K, M < 1 Msun and hot (Herbig Ae/Be; 7000 < T(K) < 13000; 1 < M(Msun) < 6) pre-main sequence (PMS) stars. This comparison gives insight into the analogies/differences in the physics of the star-disk interaction and in the physical mechanisms driving disk dissipation. Several optical and near-IR line luminosities used for low-mass objects are also valid to estimate typical accretion rates for intermediate-mass stars under similar empirical expressions. In contrast, the Halpha width at 10% of peak intensity is used as an accretion tracer for T Tauris, but is not reliable to estimate accretion rates for Herbig Ae/Bes. This can be explained as a consequence of the different stellar rotation rates that characterize both types of stars. In addition, there are similar trends when the accretion rate is related to the near-IR colours and disk masses, suggesting that viscous ... 8. Searching for Star-Planet interactions within the magnetosphere of HD 189733 OpenAIRE Fares, R.; Donati, J.-F.; Moutou, C.; Jardine, M. M.; Griessmeier, J. -M.; Zarka, P.; Shkolnik, E. L.; Bohlender, D.; Catala, C.; Cameron, A. C. 2010-01-01 HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (June 2007 and July 2008). HD 189733 has a mainly toroidal ... 9. A resolved debris disk around the candidate planet-hosting star HD95086 OpenAIRE Moór, A.; Ábrahám, P.; Kóspál, Á.; Szabó, Gy. M.; Apai, D.; Balog, Z.; Csengeri, T.; Grady, C; Henning, Th.; Juhász, A.; Kiss, Cs; Pascucci, I.; Szulágyi, J.; Vavrek, R. 2013-01-01 Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD95086. The strong infrared excess of the system indicates that, similarly to HR8799, {\\ss} Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD95086 disk, and to investigate its possible interaction with the newly discovered planet, here we present new optical, infrared and millimeter observations. We detected no CO emission,... 10. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii DEFF Research Database (Denmark) Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; 2014-01-01 AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations...... of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(-0.45)(+0.18), 2.29(-0.82)(+0.96), and 9.33(-2.18)(+6.07) keV, or an optically thin thermal plasma... 11. EFFECT OF PHOTODESORPTION ON THE SNOW LINES AT THE SURFACE OF OPTICALLY THICK CIRCUMSTELLAR DISKS AROUND HERBIG Ae/Be STARS International Nuclear Information System (INIS) We investigate the effect of photodesorption on the snow line position at the surface of a protoplanetary disk around a Herbig Ae/Be star, motivated by the detection of water ice particles at the surface of the disk around HD142527 by Honda et al. For this aim, we obtain the density and temperature structure in the disk with a 1+1D radiative transfer and determine the distribution of water ice particles in the disk by the balance between condensation, sublimation, and photodesorption. We find that photodesorption induced by far-ultraviolet radiation from the central star depresses the ice-condensation front toward the mid-plane and pushes the surface snow line significantly outward when the stellar effective temperature exceeds a certain critical value. This critical effective temperature depends on the stellar luminosity and mass, the water abundance in the disk, and the yield of photodesorption. We present an approximate analytic formula for the critical temperature. We separate Herbig Ae/Be stars into two groups on the HR diagram according to the critical temperature: one is the disks where photodesorption is effective and from which we may not find ice particles at the surface, and the other is the disks where photodesorption is not effective. We estimate the snow line position at the surface of the disk around HD142527 to be 100-300 AU, which is consistent with the water ice detection at >140 AU in the disk. All the results depend on the dust grain size in a complex way, and this point requires more work in the future. 12. The magnetic field topology and chemical abundance distributions of the Ap star HD 32633 Science.gov (United States) Silvester, J.; Kochukhov, O.; Wade, G. A. 2015-10-01 Previous observations of the Ap star HD 32633 indicated that its magnetic field was unusually complex in nature and could not be characterized by a simple dipolar structure. Here we derive magnetic field maps and chemical abundance distributions for this star using full Stokes vector (Stokes IQUV) high-resolution observations obtained with the ESPaDOnS and Narval spectropolarimeters. Our maps, produced using the INVERS10 magnetic Doppler imaging (MDI) code, show that HD 32633 has a strong magnetic field which features two large regions of opposite polarity but deviates significantly from a pure dipole field. We use a spherical harmonic expansion to characterize the magnetic field and find that the harmonic energy is predominately in the ℓ = 1 and 2 poloidal modes with a small toroidal component. At the same time, we demonstrate that the observed Stokes parameter profiles of HD 32633 cannot be fully described by either a dipolar or dipolar plus quadrupolar field geometry. We compare the magnetic field topology of HD 32633 with other early-type stars for which MDI analyses have been performed, supporting a trend of increasing field complexity with stellar mass. We then compare the magnetic field topology of HD 32633 with derived chemical abundance maps for the elements Mg, Si, Ti, Cr, Fe, Ni and Nd. We find that the iron-peak elements show similar distributions, but we are unable to find a clear correlation between the location of local chemical enhancements or depletions and the magnetic field structure. 13. CHEMICAL ABUNDANCES OF THE MAGNETIC CP STAR HD 168733 Directory of Open Access Journals (Sweden) Ana Collado 2009-01-01 Full Text Available Se ha llevado a cabo un an lisis detallado de las abundancias en la estrella CP magn tica HD 168733 utilizando espectros de alta resoluci n obtenidos con el espectr grafo echelle EBASIM del telescopio de 2.1 m de CASLEO en Argentina. Los espectros cubren la regi n 382{700 nm. La estrella no puede ser clasi cada ni como una peculiar de HgMn ni como perteneciente al grupo CP2 de silicio. Comparada con el Sol, C, N son levementes sobreabundantes mientras que el Mg y S son de cientes, Si es normal y P y Cl son sobreabundantes. Los elementos del pico de hierro: Sc, Ti, Cr y Fe son sobreabundantes. Se han identi cado tambi n l neas de Ti III y Fe III. HD 168733 muestra una gran sobreabundancia de Ga, Sr, Y, Zr, Xe, Pt, Hg y algunas tierras raras. 14. Confirmation of the magnetic nature of the delta Scuti star HD 21190 Science.gov (United States) Hubrig, S.; Scholler, M. 2016-06-01 HD 21190 is a known delta Scuti star showing Ap star characteristics and a variability period of 3.6h discovered by the Hipparcos mission. Our previous spectropolarimetric observations with FORS1 at the VLT showed the presence of a rather weak magnetic field of the order of a few tens of Gauss. New spectropolarimetric measurements with FORS2 at the VLT reveal that the magnetic field in this star is much stronger, about -250G, indicating that also Ap stars can pulsate in the delta Scuti range. 15. Line Identification of the Si Star HD 87240 Directory of Open Access Journals (Sweden) C. Saffe 2004-01-01 Full Text Available Se presentan las identificaciones de las líneas de la estrella peculiar tipo Ap Si HD 87240 (_ = - 59_ 51 00:1 en el intervalo espectral 3710{5520. Este objeto es miembro del cúmulo abierto meridional NGC 3114. La comparación de este objeto con otras estrellas Ap Si del campo muestra que tienen en común muchas de las anomalías en sus líneas. 16. The Mid-Infrared Polarization of the Herbig Ae Star WL 16: An Interstellar Origin? CERN Document Server Zhang, Han; Pantin, Eric; Li, Dan; Wright, Christopher M; Mariñas, Naibí; Barnes, Peter; Li, Aigen; Packham, Christopher 2016-01-01 We present high-resolution (0".4) mid-infrared (mid-IR) polarimetric images and spectra of WL 16, a Herbig Ae star at a distance of 125 pc. WL 16 is surrounded by a protoplanetary disk of\\sim$900 AU in diameter, making it one of the most extended Herbig Ae/Be disks as seen in the mid-IR. The star is behind, or embedded in, the$\\rhoOphiuchus molecular cloud, and obscured by 28 magnitudes of extinction at optical wavelengths by the foreground cloud. Mid-IR polarization of WL 16, mainly arises from aligned elongated dust grains present along the line of sight, suggesting a uniform morphology of polarization vectors with an orientation of 33\\degr (East from North) and a polarization fraction of\\sim2.0\\%. This orientation is consistent with previous polarimetric surveys in the optical and near-IR bands to probe large-scale magnetic fields in the Ophiuchus star formation region, indicating that the observed mid-IR polarization toward WL 16 is produced by the dichroic absorption of magnetically aligned for... 17. Quasiperiodic patterns in\\delta$Scuti stars: an in-depth study of the CoRoT star HD 174966 CERN Document Server Hernández, A García; Suárez, J C; Garrido, R; Mantegazza, L; Martín-Ruiz, S; Rainer, M; Poretti, E; Amado, P J; Rolland, A; Mathias, P; Uytterhoeven, K 2016-01-01 In this work, we have gone one step further from the study presented in the first CoRoT symposium. Our analysis consists on constructing a model database covering the entire uncertainty box of the$\\delta$Sct star HD174966, derived from the usual observables ($\\mathrm{T}_{\\mathrm{eff}}$,$\\log g$and [Fe/H]), and constraining the models representative of the star. To do that, we use the value of the periodicity (related to$\\Delta\
18. High Resolution Time-resolved UCLES Spectroscopy of AE Aqr: I. The Secondary Star Revealed
Science.gov (United States)
Echevarria, J.; Diego, F.; Mills, D.; Connon Smith, R.
2006-06-01
High-dispersion time-resolved spectroscopy of the cataclysmic variable AE Aqr has been obtained. The emission lines have a complex structure that make difficult to measure the motion of the white dwarf. The cross correlation for the absorption lines shows a clear asymmetric profile as expected from a heated side of the red star. The spectral type for the secondary star varies from K2 to K5; there are clear indications that the temperature varies as a function of star longitude. The radial velocity analysis yield Kab = 165.2 ± 0.6 Km s-1 for the cross-correlated secondary star. The rotational velocity of the red star has been measured as a function of orbital period. It shows ellipsoidal variations with a period half the orbital period. The rotational velocities vary within the range Vrot sin i = 105 ± 3 Km s-1 and Vrot sin i = 130 ± 3 Km s-1. The former can be used to constrain the white dwarf semi-amplitude value to yield Kem = 139 ± 4 Km s-1 consistent with derived values from published radial velocity measurements. From a variation in the absorption line strength of 30%, we constrain the inclination angle to i = 58° ± 3. The estimated masses of the binary are: Mw = 1.07 ± 0.07 M? and Mr = 0.90 ± 0.05 M?. If this is correct we should expect a spectral type of G5 if the secondary star is a main sequence star. We suggest that the discrepancy is explained if the star has a radius 40% greater than a main sequence star for a mass of 0.90 M?.
19. The peculiar abundance pattern of the new Hg-Mn star HD 30085
CERN Document Server
Monier, R; Royer, F; Griffin, R E M
2015-01-01
Using high-dispersion, high-quality spectra of HD 30085 obtained with the echelle spectrograph SOPHIE at Observatoire de Haute Provence, we show that this star contains strong lines of the s-process elements Sr II, Y II and Zr II. Line syntheses of the lines yield large overabundances of Sr, Y, Zr which are characteristic of HgMn stars. The Sr-Y-Zr triad of abundances is inverted in HD 30085 compared to that in our solar system. The violation of the odd-even rule suggests that physical processes such as radiative diffusion, chemical fractionation and others must be at work in the atmosphere of HD 30085, and that the atmosphere is stable enough to sustain them.
20. HD 101065, the Most Peculiar Star: First Results from Precise Radial Velocity Study
D. E. Mkrtichian; A. P. Hatzes
2005-06-01
In this paper we discuss the prospects for asteroseismology with spatial resolution and motivate studies of the most chemically peculiar roAp star HD 101065. We present the first results from a high-precision radial velocity (RV) study of HD 101065 based on data spanning four nights that were acquired using the HARPS echelle-spectrometer at the ESO 3.6 m telescope. The analysis of individual nights showed the amplitude and phase modulation of the dominant mode. The analysis of the whole data set showed the presence of multi-periodic oscillations with two groups of equally-spaced modes. We find = 65.2 Hz and = 7.3 Hz for the large and the small spacing, respectively. HD 101065 is the only roAp star to show the existence of two groups of = 0, 2 and = 1, 3 excited modes.
1. The color dependent morphology of the post-AGB star HD161796
CERN Document Server
Min, M; Canovas, H; Rodenhuis, M; Keller, C U; Waters, L B F M
2013-01-01
Context. Many protoplanetary nebulae show strong asymmetries in their surrounding shell, pointing to asymmetries during the mass loss phase. Questions concerning the origin and the onset of deviations from spherical symmetry are important for our understanding of the evolution of these objects. Here we focus on the circumstellar shell of the post-AGB star HD 161796. Aims. We aim at detecting signatures of an aspherical outflow, as well as to derive the properties of it. Methods. We use the imaging polarimeter ExPo (the extreme polarimeter), a visitor instrument at the William Herschel Telescope, to accurately image the dust shell surrounding HD 161796 in various wavelength filters. Imaging polarimetry allows us to separate the faint, polarized, light from circumstellar material from the bright, unpolarized, light from the central star. Results. The shell around HD 161796 is highly aspherical. A clear signature of an equatorial density enhancement can be seen. This structure is optically thick at short wavelen...
2. Surface structure of the CoRoT CP2 target star HD 50773
OpenAIRE
Lüftinger, T.; Fröhlich, H. -E.; Weiss, W.; Petit, P.; Aurière, M.; Nesvacil, N.; Gruberbauer, M.; Shulyak, D.; Alecian, E.; Baglin, A.; Baudin, F; Catala, C.; Donati, J.-F.; Kochukhov, O.; Michel, E.
2009-01-01
We compare surface maps of the chemically peculiar star HD 50773 produced with a Bayesian technique and based on high quality CoRoT photometry with those derived from rotation phase resolved spectropolarimetry. The goal is to investigate the correlation of surface brightness with surface chemical abundance distribution and the stellar magnetic field. The rotational period of the star was determined from a nearly 60 day long continuous light curve obtained during the initial run of CoRoT. Usin...
3. Elodie metallicity-biased search for transiting Hot Jupiters IV. Intermediate period planets orbiting the stars HD43691 and HD132406
OpenAIRE
da Silva, R.; Udry, S.; Bouchy, F.; Moutou, C.; Mayor, M.; Beuzit, J.-L.; Bonfils, X.; Delfosse, X.; Desort, M.; Forveille, T.; Galland, F.; Hebrard, G.; Lagrange, A.-M.; Loeillet, B.; Lovis, C.
2007-01-01
We report here the discovery of two planet candidates as a result of our planet-search programme biased in favour of high-metallicity stars, using the ELODIE spectrograph at the Observatoire de Haute Provence. One of them has a minimum mass m_2\\sin{i} = 2.5 M_Jup and is orbiting the metal-rich star HD43691 with period P = 40 days and eccentricity e = 0.14. The other planet has a minimum mass m_2\\sin{i} = 5.6 M_Jup and orbits the slightly metal-rich star HD132406 with period P = 974 days and e...
4. A resolved, au-scale gas disk around the B[e] star HD 50138
NARCIS (Netherlands)
L.E. Ellerbroek; M. Benisty; S. Kraus; K. Perraut; J. Kluska; J.B. de Bouquin; M. Borges Fernandes; A. Domiciano de Souza; K.M. Maaskant; L. Kaper; F. Tramper; D. Mourard; I. Tallon-Bosc; T. ten Brummelaar; M.L. Sitko; D.K. Lynch; R.W. Russell
2015-01-01
HD 50138 is a B[e] star surrounded by a large amount of circumstellar gas and dust. Its spectrum shows characteristics which may indicate either a pre- or a post-main-sequence system. Mapping the kinematics of the gas in the inner few au of the system contributes to a better understanding of its phy
5. The circumstellar envelope of the C-rich post-AGB star HD 56126
NARCIS (Netherlands)
Hony, S; Tielens, AGGM; Waters, LBFM; de Koter, A
2003-01-01
We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch "21 mum object" HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model th
6. Discovery of non-radial pulsations in the spectroscopic binary Herbig Ae star RS Cha
CERN Document Server
Böhm, T; Catala, C; Alecian, E; Pollard, K; Wright, D
2008-01-01
In this article we present a first discovery of non radial pulsations in both components of the Herbig Ae spectroscopic binary star RS Cha. The binary was monitored in quasi-continuous observations during 14 observing nights (Jan 2006) at the 1m Mt John (New Zealand) telescope with the Hercules high-resolution echelle spectrograph. The cumulated exposure time on the star was 44 hrs, corresponding to 255 individual high-resolution echelle spectra with $R = 45000$. Least square deconvolved spectra (LSD) were obtained for each spectrum representing the effective photospheric absorption profile modified by pulsations. Difference spectra were calculated by subtracting rotationally broadened artificial profiles; these residual spectra were analysed and non-radial pulsations were detected. A subsequent analysis with two complementary methods, namely Fourier Parameter Fit (FPF) and Fourier 2D (F2D) has been performed and first constraints on the pulsation modes have been derived. In fact, both components of the spect...
7. First discovery of a magnetic field in a main-sequence δ Scuti star: the Kepler star HD 188774
Science.gov (United States)
Neiner, C.; Lampens, P.
2015-11-01
The Kepler space mission provided a wealth of δ Sct-γ Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related surface inhomogeneities. In particular, the Kepler δ Sct-γ Dor hybrid candidate HD 188774 shows a few low frequencies in its light and radial velocity curves, whose origin is unclear. In this work, we check for the presence of a magnetic field in HD 188774. We obtained two spectropolarimetric measurements with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) at Canada-France-Hawaii Telescope. The data were analysed with the least-squares deconvolution (LSD) method. We detected a clear magnetic signature in the Stokes V LSD profiles. The origin of the low frequencies detected in HD 188774 is therefore most probably the rotational modulation of surface spots possibly related to the presence of a magnetic field. Consequently, HD 188774 is not a genuine hybrid δ Sct-γ Dor star, but the first known magnetic main-sequence δ Sct star. This makes it a prime target for future asteroseismic and spot modelling. This result casts new light on the interpretation of the Kepler results for other δ Sct-γ Dor hybrid candidates.
8. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements
CERN Document Server
Alecian, E; Catala, C; Grunhut, J H; Landstreet, J D; Bagnulo, S; Böhm, T; Folsom, C P; Marsden, S; Waite, I
2012-01-01
This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly-polarised spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterised by a resolving power of about 65,000, and a spectral coverage from about 3700 ang to 1 micron. The peak SNR per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this first paper, we describe the sample selection, ...
9. A parameter study of self-consistent disk models around Herbig AeBe stars
CERN Document Server
Meijer, J; De Koter, A; Dullemond, C P; Van Boekel, R; Waters, L B F M
2008-01-01
We present a parameter study of self-consistent models of protoplanetary disks around Herbig AeBe stars. We use the code developed by Dullemond and Dominik, which solves the 2D radiative transfer problem including an iteration for the vertical hydrostatic structure of the disk. This grid of models will be used for several studies on disk emission and mineralogy in followup papers. In this paper we take a first look on the new models, compare them with previous modeling attempts and focus on the effects of various parameters on the overall structure of the SED that leads to the classification of Herbig AeBe stars into two groups, with a flaring (group I) or self-shadowed (group II) SED. We find that the parameter of overriding importance to the SED is the total mass in grains smaller than 25um, confirming the earlier results by Dullemond and Dominik. All other parameters studied have only minor influences, and will alter the SED type only in borderline cases. We find that there is no natural dichotomy between ...
10. Pulsational frequencies of the eclipsing delta-Scuti star HD 172189
CERN Document Server
Costa, J E S; Peña, J; Creevey, O; Li, Z P; Chevreton, M; Belmonte, J A; Alvarez, M; Machado, L Fox; Parrao, L; Hernendez, F Perez; Fernández, A; Fremy, J R; Pau, S; Alonso, R
2007-01-01
The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.
11. Time-resolved photometric and spectroscopic analysis of a luminous Ap star HD103498
CERN Document Server
Joshi, S; Kochukhov, O; Sachkov, M; Tiwari, S K; Chakradhari, N K; Piskunov, N
2009-01-01
We present the results on the photometric and spectroscopic monitoring of a luminous Ap star HD103498. The time-series photometric observations were carried out on 17 nights using three-channel fast photometer attached to the 1.04-m optical telescope at ARIES, Nainital. The photometric data of five nights of year 2007 show clear signature of 15-min periodicity. However, the follow-up observations during 2007--2009 could not repeated any such periodicity. To confirm the photometric light variations, the time-series spectroscopic observations were carried out with the 2.56-m Nordic Optical Telescope (NOT) at La Palma on February 2, 2009. Any radial velocity variations were absent in this data set which is in full agreement with the photometric observations taken near the same night. Model atmosphere and abundance analysis of HD103498 show that the star is evolved from the Main Sequence and its atmospheric abundances are similar to two other evolved Ap stars HD133792 and HD204411: large overabundances of Si, Cr,...
12. B[e] stars at the highest angular resolution: the case of HD87643
CERN Document Server
Millour, Florentin; Borges-Fernandes, Marcelo; Meilland, Anthony
2009-01-01
New results on the B[e] star HD87643 are presented here. They were obtained with a wide range of di?erent instruments, from wide-?eld imaging with the WFI camera, high resolution spectroscopy with the FEROS instrument, high angular resolution imaging with the adaptive optics camera NACO, to the highest angular resolution available with AMBER on the VLTI. We report the detection of a companion to HD87643 with AMBER, subsequently con?rmed in the NACO data. Implications of that discovery to some of the previously di?cult-to-understand data-sets are then presented.
13. Coordinated X-ray and Optical observations of Star-Planet Interaction in HD 17156
OpenAIRE
Maggio, A.; Pillitteri, I.; Scandariato, G.; Lanza, A. F.; Sciortino, S.; Borsa, F.; Bonomo, A. S.; Claudi, R.; Covino, E.; Desidera, S.; R. Gratton; Micela, G.; Pagano, I.; Piotto, G.; Sozzetti, A.
2015-01-01
The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focused our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. Here we present results of the XMM-Newton observations and of a five months coordinated optical campaign with the HARPS-N spectrograph. We observed HD 17156 with XMM-Newton when the planet was approaching the apoastron and then at the following periastron...
14. HD15082b, a short-period planet orbiting an A-star
OpenAIRE
Lodieu N.; Smalley B.; Rodler F.; Cameron A.C.; Guenther E.W.; Endl M.; Reif K.
2011-01-01
Most of the known transiting extrasolar planets orbit slowly rotating F, G or K stars. In here we report on the detection of a transiting planet orbiting the bright, rapidly rotating A5 star HD15082, recently made by SuperWASP. Time resolved spectroscopic observations taken during transit show a hump caused by the planet crossing the line profile. From the analysis of the spectra, we derive the radius of the planet and find that it is orbiting retrograde in respect to the spin of the star...
15. Accurate fundamental parameters of CoRoT asteroseismic targets: the solar-like stars HD 49933, HD 175726, HD 181420 and HD 181906
CERN Document Server
Bruntt, H
2009-01-01
The CoRoT satellite has provided high-quality light curves of several solar-like stars. Analysis of the light curves provides oscillation frequencies that make it possible to probe the interior of the stars. However, additional constraints on the fundamental parameters of the stars are important for the theoretical modelling to be successful. We will estimate the fundamental parameters (mass, radius and luminosity) of the first four solar-like targets to be observed in the asteroseismic field. In addition, we will determine their effective temperature, metallicity and detailed abundance pattern. To constrain the stellar mass, radius and age we use the SHOTGUN software which compares the location of the stars in the Hertzsprung-Russell diagram with theoretical evolution models. This method takes into account the uncertainties of the observed parameters including the large separation determined from the solar-like oscillations. We determine the effective temperatures and abundance patterns in the stars from the...
16. The nature of the light variability of magnetic Of?p star HD 191612
Science.gov (United States)
Krtička, J.
2016-10-01
Context. A small fraction of hot OBA stars host global magnetic fields with field strengths of the order of 0.1-10 kG. This leads to the creation of persistent surface structures (spots) in stars with sufficiently weak winds as a result of the radiative diffusion. These spots become evident in spectroscopic and photometric variability. This type of variability is not expected in stars with strong winds, where the wind inhibits the radiative diffusion. Therefore, a weak photometric variability of the magnetic Of?p star HD 191612 is attributed to the light absorption in the circumstellar clouds. Aims: We study the nature of the photometric variability of HD 191612. We assume that the variability results from variable wind blanketing induced by surface variations of the magnetic field tilt and modulated by stellar rotation. Methods: We used our global kinetic equilibrium (NLTE) wind models with radiative force determined from the radiative transfer equation in the comoving frame (CMF) to predict the stellar emergent flux. Our models describe the stellar atmosphere in a unified manner and account for the influence of the wind on the atmosphere. The models are calculated for different wind mass-loss rates to mimic the effect of magnetic field tilt on the emergent fluxes. We integrate the emergent fluxes over the visible stellar surface for individual rotational phases, and calculate the rotationally modulated light curve of HD 191612. Results: The wind blanketing that varies across surface of HD 191612 is able to explain a part of the observed light variability in this star. The mechanism is able to operate even at relatively low mass-loss rates. The remaining variability is most likely caused by the flux absorption in circumstellar clouds. Conclusions: The variable wind blanketing is an additional source of the light variability in massive stars. The presence of the rotational light variability may serve as a proxy for the magnetic field.
17. HD 30187 B and HD 39927 B: Two suspected nearby hot subdwarfs in resolved binaries (based on observations made with the ESA Hipparcos satellite)
DEFF Research Database (Denmark)
Makarov, V.V.; Fabricius, C.
1999-01-01
Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual......Stars: Individual: HD 30187 B -- Stars: Individual: HD 39927 B - Stars: White dwarfs - Stars: Binaries: Visual...
18. A high-resolution spectropolarimetric survey of Herbig Ae/Be stars - I. Observations and measurements
Science.gov (United States)
Alecian, E.; Wade, G. A.; Catala, C.; Grunhut, J. H.; Landstreet, J. D.; Bagnulo, S.; Böhm, T.; Folsom, C. P.; Marsden, S.; Waite, I.
2013-02-01
This is the first in a series of papers in which we describe and report the analysis of a large survey of Herbig Ae/Be stars in circular spectropolarimetry. Using the ESPaDOnS and Narval high-resolution spectropolarimeters at the Canada-France-Hawaii and Bernard Lyot Telescopes, respectively, we have acquired 132 circularly polarized spectra of 70 Herbig Ae/Be stars and Herbig candidates. The large majority of these spectra are characterized by a resolving power of about 65 000, and a spectral coverage from about 3700 Å to 1 μm. The peak signal-to-noise ratio per CCD pixel ranges from below 100 (for the faintest targets) to over 1000 (for the brightest). The observations were acquired with the primary aim of searching for magnetic fields in these objects. However, our spectra are suitable for a variety of other important measurements, including rotational properties, variability, binarity, chemical abundances, circumstellar environment conditions and structure, etc. In this paper, we describe the sample selection, the observations and their reduction, and the measurements that will comprise the basis of much of our following analysis. We describe the determination of fundamental parameters for each target. We detail the least-squares deconvolution (LSD) that we have applied to each of our spectra, including the selection, editing and tuning of the LSD line masks. We describe the fitting of the LSD Stokes I profiles using a multicomponent model that yields the rotationally broadened photospheric profile (providing the projected rotational velocity and radial velocity for each observation) as well as circumstellar emission and absorption components. Finally, we diagnose the longitudinal Zeeman effect via the measured circular polarization, and report the longitudinal magnetic field and Stokes V Zeeman signature detection probability. As an appendix, we provide a detailed review of each star observed.
19. Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753
OpenAIRE
Briquet, Maryline; Korhonen, H.; González, J.F.; Hubrig, S.; Hackman, T.
2010-01-01
Aims: We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. Methods: Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surfa...
20. An Eccentric Debris Ring Around the Nearby G Star HD 202628
Science.gov (United States)
Stapelfeldt, Karl R.
2012-01-01
A new debris disk has been imaged in visible light around the G2V star HD 202628 using the STIS coronagraph on the Hubble Space Telescope. The broad ring is inclined 61 deg from face-on and extends as far as 260 AU from the star. The star is noticeably displaced from the apparent ring center by 20 AU. The ring inner edge is sharp and well-described by an inclined ellipse with a= 158 AU, e= 0.18, and the star at one focus. These properties are similar to the Fomalhaut debris ring and likewise suggest ring sculpting by a planetary-mass companion with semi-major axis approx.> 100 AU. The presence of a planet so widely separated from a solar-type star poses a new challenge for planet formation theories.
1. Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753
CERN Document Server
Briquet, M; Gonzalez, J F; Hubrig, S; Hackman, T
2010-01-01
Aims. We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements. Methods. Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. Results. For HD 11753, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for HD 53244 and HD 221507 the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P_rot (HD 11753)=9.54 d, P_rot (HD 53244)=6.16 d, and P_rot (HD 221507)=...
2. Lithium and magnetic fields in giants. HD 232862 : a magnetic and lithium-rich giant star
CERN Document Server
Lèbre, A; Nascimento, J D do; Konstantinova-Antova, R; Kolev, D; Aurière, M; De Laverny, P; De Medeiros, J R
2009-01-01
We report the detection of an unusually high lithium content in HD 232862, a field giant classified as a G8II star, and hosting a magnetic field. With the spectropolarimeters ESPaDOnS at CFHT and NARVAL at TBL, we have collected high resolution and high signal-to-noise spectra of three giants : HD 232862, KU Peg and HD 21018. From spectral synthesis we have inferred stellar parameters and measured lithium abundances that we have compared to predictions from evolutionary models. We have also analysed Stokes V signatures, looking for a magnetic field on these giants. HD 232862, presents a very high abundance of lithium (ALi = 2.45 +/- 0.25 dex), far in excess of the theoretically value expected at this spectral type and for this luminosity class (i.e, G8II). The evolutionary stage of HD 232862 has been precised, and it suggests a mass in the lower part of the [1.0 Msun ; 3.5 Msun ] mass interval, likely 1.5 to 2.0 solar mass, at the bottom of the Red Giant Branch. Besides, a time variable Stokes V signature has...
3. Stellar Diameters and Temperatures VI. High angular resolution measurements of the transiting exoplanet host stars HD 189733 and HD 209458 and implications for models of cool dwarfs
CERN Document Server
Boyajian, Tabetha; Feiden, Gregory A; Huber, Daniel; Basu, Sarbani; Demarque, Pierre; Fischer, Debra A; Schaefer, Gail; Mann, Andrew W; White, Timothy R; Maestro, Vicente; Brewer, John; Lamell, C Brooke; Spada, Federico; López-Morales, Mercedes; Ireland, Michael; Farrington, Chris; van Belle, Gerard T; Kane, Stephen R; Jones, Jeremy; Brummelaar, Theo A ten; Ciardi, David R; McAlister, Harold A; Ridgway, Stephen; Goldfinger, P J; Turner, Nils H; Sturmann, Laszlo
2014-01-01
We present direct radii measurements of the well-known transiting exoplanet host stars HD 189733 and HD 209458 using the CHARA Array interferometer. We find the limb-darkened angular diameters to be theta_LD = 0.3848 +/- 0.0055 and 0.2254 +/- 0.0072 milliarcsec for HD 189733 and HD 209458, respectively. HD 189733 and HD 209458 are currently the only two transiting exoplanet systems where detection of the respective planetary companion's orbital motion from high resolution spectroscopy has revealed absolute masses for both star and planet. We use our new measurements together with the orbital information from radial velocity and photometric time series data, Hipparcos distances, and newly measured bolometric fluxes to determine the stellar effective temperatures (T_eff = 4875 +/- 43, 6093 +/- 103 K), stellar linear radii (R_* = 0.805 +/- 0.016, 1.203 +/- 0.061 R_sun), mean stellar densities (rho_* = 1.62 +/- 0.11, 0.58 +/- 0.14 rho_sun), planetary radii (R_p = 1.216 +/- 0.024, 1.451 +/- 0.074 R_Jup), and mean ...
4. Magnetism and binarity of the Herbig Ae star V380 Ori
CERN Document Server
Alecian, E; Catala, C; Bagnulo, S; Böhm, T; Bouret, J -C; Donati, J -F; Folsom, C P; Grunhut, J; Landstreet, J D
2009-01-01
In this paper we report the results of high-resolution circular spectropolarimetric monitoring of the Herbig Ae star V380 Ori, in which we discovered a magnetic field in 2005. A careful study of the intensity spectrum reveals the presence of a cool spectroscopic companion. By modelling the binary spectrum we infer the effective temperature of both stars: $10500\\pm 500$ K for the primary, and $5500\\pm500$ K for the secondary, and we argue that the high metallicity ($[M/H] = 0.5$), required to fit the lines may imply that the primary is a chemically peculiar star. We observe that the radial velocity of the secondary's lines varies with time, while that of the the primary does not. By fitting these variations we derive the orbital parameters of the system. We find an orbital period of $104\\pm5$ d, and a mass ratio ($M_{\\rm P}/M_{\\rm S}$) larger than 2.9. The intensity spectrum is heavily contaminated with strong, broad and variable emission. A simple analysis of these lines reveals that a disk might surround the...
5. A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars
CERN Document Server
Brittain, Sean D; Carr, John S; Ádámkovics, Máté; Reynolds, Nickalas
2016-01-01
We present a study of ro-vibrational OH and CO emission from 21 disks around Herbig Ae/Be stars. We find that the OH and CO luminosities are proportional over a wide range of stellar ultraviolet luminosities. The OH and CO line profiles are also similar, indicating that they arise from roughly the same radial region of the disk. The CO and OH emission are both correlated with the far-ultraviolet luminosity of the stars, while the PAH luminosity is correlated with the longer wavelength ultraviolet luminosity of the stars. Although disk flaring affects the PAH luminosity, it is not a factor in the luminosity of the OH and CO emission. These properties are consistent with models of UV-irradiated disk atmospheres. We also find that the transition disks in our sample, which have large optically thin inner regions, have lower OH and CO luminosities than non-transition disk sources with similar ultraviolet luminosities. This result, while tentative given the small sample size, is consistent with the interpretation t...
6. Investigating the origin of hot gas lines in Herbig Ae/Be Stars
CERN Document Server
Cauley, P Wilson
2016-01-01
We analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBES) in order to explore the origin of the $T\\sim10^5$ K gas in these stars. The C IV 1548,1550 \\AA\\ line luminosities are compared to non--simultaneous accretion rate estimates for the objects showing C IV emission. We show that the correlation between $L_{CIV}$ and $\\dot{M}$ previously established for classical T Tauri stars (CTTSs) seems to extend into the HAEBE mass regime, although the large spread in literature $\\dot{M}$ and $A_V$ values makes the actual relationship highly uncertain. With the exception of DX Cha, we find no evidence for hot, optically thick winds in our HAEBE sample. All other objects showing clear doublet emission in C IV can be well described by a two component (i.e., a single component for each doublet member) or four component (i.e., two components for each doublet member) Gaussian emission line fit. The morphologies and peak-flux velocities of these lines suggest they are formed in weak, optically th...
7. The optical counterpart of IRAS 12496 - 7650 - A highly embedded Herbig AE star
Science.gov (United States)
Hughes, J. D.; Hartigan, P.; Graham, J. A.; Emerson, J. P.; Marang, F.
1991-03-01
Optical and near-infrared observations of IRAS 12496 - 7650, an active young star and the most luminous IRAS source in the Chamaeleon II dark cloud, are reported. The object has become brighter at optical wavelengths since 1976, and has exhibited variations of more than a magnitude at K between January 1987 and May 1990. IRAS 12496 - 7650 is redder when fainter, and the amplitude of the brightness fluctuations decreases toward longer infrared wavelengths. Differing amounts of circumstellar extinction or intrinsic color variations of the source can produce most of the observed variability. Optical spectra confirm that IRAS 12496 - 7650 is an extremely active (probably Herbig Ae type) star with blueshifted forbidden lines of O I and S II and a prominent P-Cygni profile at H-alpha. The S II emission extends 3-4 arcsec on either side of the star and shows a significant velocity gradient, suggestive of a jetlike structure. The detection of outflowing material from IRAS 12496 - 7650 reinforces earlier evidence that this object is the exciting source for the HH 52 - 54 group Herbig-Haro objects. The broad spectral energy distribution suggests that IRAS 12496 - 7650 has a circumstellar disk.
8. High-resolution 25 \\mu m imaging of the disks around Herbig Ae/Be stars
CERN Document Server
Honda, M; Okamoto, Y K; Kataza, H; Yamashita, T; Miyata, T; Sako, S; Fujiyoshi, T; Sakon, I; Fujiwara, H; Kamizuka, T; Mulders, G D; Lopez-Rodriguez, E; Packham, C; Onaka, T
2015-01-01
We imaged circumstellar disks around 22 Herbig Ae/Be stars at 25 \\mu m using Subaru/COMICS and Gemini/T-ReCS. Our sample consists of equal numbers of objects belonging to the two categories defined by Meeus et al. (2001); 11 group I (flaring disk) and II (at disk) sources. We find that group I sources tend to show more extended emission than group II sources. Previous studies have shown that the continuous disk is hard to be resolved with 8 meter class telescopes in Q-band due to the strong emission from the unresolved innermost region of the disk. It indicates that the resolved Q-band sources require a hole or gap in the disk material distribution to suppress the contribution from the innermost region of the disk. As many group I sources are resolved at 25 \\mu m, we suggest that many, not all, group I Herbig Ae/Be disks have a hole or gap and are (pre-)transitional disks. On the other hand, the unresolved nature of many group II sources at 25 \\mu m supports that group II disks have continuous at disk geometr...
9. NuSTAR AND SWIFT Observations of the Fast Rotating Magnetized White Dwarf AE Aquarii
Science.gov (United States)
Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; Gotthelf, Eric V.; Hayashi, Takayuki; Kaspi, Victoria M.; Rana, Vikram R.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Hailey, Charles J.; Harrison, Fiona A.; Stern, Daniel; Zhang, Will W.
2014-01-01
AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P(sub spin) = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (LX (is) approximately 10(exp 31) erg per second). We have analyzed overlapping observations of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(+0.18 / -0.45), 2.29(+0.96 / -0.82), and 9.33 (+6.07 / -2.18) keV, or an optically thin thermal plasma model with two temperatures of 1.00 (+0.34 / -0.23) and 4.64 (+1.58 / -0.84) keV plus a power-law component with photon index of 2.50 (+0.17 / -0.23). The pulse profile in the 3-20 keV band is broad and approximately sinusoidal, with a pulsed fraction of 16.6% +/- 2.3%. We do not find any evidence for a previously reported sharp feature in the pulse profile.
10. Abundances in the atmosphere of the metal-rich planet-host star HD 77338
CERN Document Server
Kushniruk, I O; Jenkins, J S; Jones, H R A
2015-01-01
Abundances of Fe, Si, Ni, Ti, Na, Mg, Cu, Zn, Mn, Cr and Ca in the atmosphere of the K-dwarf HD 77338 are determined and discussed. HD 77338 hosts a hot Uranus-like planet and is currently the most metal-rich single star to host any planet. Determination of abundances was carried out in the framework of a self-consistent approach developed by Pavlenko et al. (2012). Abundances were computed iteratively by the program ABEL8, and the process converged after 4 iterations. We find that most elements follow the iron abundance, however some of the iron peak elements are found to be over-abundant in this star.
11. An Ionized Outflow from AB Aur, a Herbig Ae Star with a Transitional Disk
CERN Document Server
Rodriguez, Luis F; Dzib, Sergio A; Ortiz-Leon, Gisela; Loinard, Laurent; Macias, Enrique; Anglada, Guillem
2014-01-01
AB Aur is a Herbig Ae star with a transitional disk. Transitional disks present substantial dust clearing in their inner regions, most probably because of the formation of one or more planets, although other explanations are still viable. In transitional objects, accretion is found to be about an order of magnitude smaller than in classical full disks. Since accretion is believed to be correlated with outflow activity, centimeter free-free jets are expected to be present in association with these systems, at weaker levels than in classical protoplanetary (full) systems. We present new observations of the centimeter radio emission associated with the inner regions of AB Aur and conclude that the morphology, orientation, spectral index and lack of temporal variability of the centimeter source imply the presence of a collimated, ionized outflow. The radio luminosity of this radio jet is, however, about 20 times smaller than that expected for a classical system of similar bolometric luminosity. We conclude that c...
12. Confirming HD 23478 as a new magnetic B star hosting an H$\\alpha$-bright centrifugal magnetosphere
OpenAIRE
Sikora, James; Wade, Gregg; Bohlender, David; Neiner, Coralie; Oksala, Mary; Shultz, Matt; Cohen, David; ud-Doula, Asif; Grunhut, Jason; Monin, Dmitry; Owocki, Stan; Petit, Véronique; Rivinius, Thomas; Townsend, Richard
2015-01-01
In this paper we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high resolution Stokes $V$ spectra using the ESPaDOnS (CFHT) and Narval (TBL) spectropolarimeters, and 11 from medium resolution Stokes $V$ spectra obtained with the DimaPol spectropolarimeter (DAO). HD 23478 was one of two rapidly rotating stars identified as potential "centrifugal magnetosphere" hosts based on IR observations from the Apache Point Observatory Galactic Evolution Experiment surv...
13. HD 98800: An Opportunity to Measure True Masses for Low-Mass PMS Stars
Science.gov (United States)
Soderblom, David
1999-07-01
HD 98800 became interesting when IRAS found it to have a large infrared excess, indicating a substantial dust disk. But HD 98800'' is, in fact, a quadruple system consisting of four K and M stars, and its Hipparcos parallax has now shown that this is a pre-main sequence system. The four stars are in two visible objects, each of which is a spectroscopic binary with a period of about one year. In particular, the Ba-Bb pair is an SB2 with an estimated semi-major axis of about 20 milliarcsec. In TRANS mode, FGS1R can cleanly resolve the Ba-Bb pair and can determine the relative orbit and luminosities for the two components. POS mode observations lead to an absolute orbit and a more precise parallax than is currently available. In this program we propose to follow the HD 98800 Ba-Bb pair over the course of a full orbit during Cycle 8. The combination of FGS1R-TRANS and FGS1R-POS observations will provide gravitational masses for two low-mass PMS stars. In addition, the co nstraints of coevality and knowled ge of the astrophysical properties of the components {temperatures, luminosities, composition} make these observations a crucial test of our models of pre-main sequence evolution. These may be the first true masses determined for low-mass PMS objects, and so can provide a fundamental test of PMS evolutionary tracks.
14. Elemental abundance studies of the Ultraviolet Gallium CP star HD 168733
Science.gov (United States)
Collado, A. E.; López-García, Z.; Levato, H.; Malaroda, S.
2009-05-01
We report elemental abundance studies of the ultraviolet gallium CP star HD 168733. It is neither a silicon, nor a mercury-manganese star and a longitudinal magnetic field of the order of -594 gauss has been detected in it. The high resolution spectra were obtained with the EBASIM spectrograph attached to the 2.10 m telescope at CASLEO Observatory. The abundances results obtained show that Si es normal, Ti Cr and Fe are rich, PII, SII, GaII, SrII, YII, ZrII are present and its abundances are being determined. The presence of RE will be also investigated.
15. Searching for a link between the magnetic nature and other observed properties of Herbig Ae/Be stars
CERN Document Server
Hubrig, S; Schöller, M; Schuetz, 0; Stelzer, B; Pogodin, M; Cure, M; Yudin, R
2009-01-01
We present the results of a new magnetic field survey of Herbig Ae/Be and A debris disk stars. They are used to determine whether magnetic field properties in these stars are correlated with the mass-accretion rate, disk inclinations, companion(s), Silicates, PAHs, or show a more general correlation with age and X-ray emission as expected for the decay of a remnant dynamo.
16. The challenge of measuring magnetic fields in strongly pulsating stars: the case of HD 96446
CERN Document Server
Järvinen, S P; Ilyin, I; Schöller, M; Briquet, M
2016-01-01
Among the early B-type stars, He-rich Bp stars exhibit the strongest large-scale organized magnetic fields with a predominant dipole contribution. The presence of $\\beta$ Cep-like pulsations in the typical magnetic early Bp-type star HD 96446 was announced a few years ago, but the analysis of the magnetic field geometry was hampered by the absence of a reliable rotation period and a sophisticated procedure for accounting for the impact of pulsations on the magnetic field measurements. Using new spectropolarimetric observations and a recently determined rotation period based on an extensive spectroscopic time series, we investigate the magnetic field model parameters of this star under more detailed considerations of the pulsation behaviour of the line profiles.
17. Detection of a white dwarf companion to the Hyades stars HD 27483
Science.gov (United States)
Boehm-Vitense, Erika
1993-01-01
We observed with IUE a white dwarf (WD) companion to the Hyades F6 V binary stars HD 27483. This system is known to be a close binary of two nearly equal stars with an orbital period of 3.05 days. Our IUE observations revealed the presence of a third star, a white dwarf with an effective temperature of 23,000 +/- 1000 K and a mass of approximately 0.6 solar mass. Its presence in the Hyades cluster with a known age permits me to derive the mass of its progenitor, which must have been about 2.3 solar masses. The presence of the white dwarf in a binary system opens the possibility that some of the envelope material, which was expelled by the WD progenitor, may have been collected by the F6 stars. We may thus be able to study abundance anomalies of the WD progenitor with known mass on the surface of the F6 companions.
18. Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI
NARCIS (Netherlands)
C. Leinert; R.J.H.M. van Boekel; L.B.F.M. Waters; O. Chesneau; F. Malbet; R. Köhler; W. Jaffe; T. Ratzka; A. Dutrey; T. Preibisch; U. Graser; E. Bakker; G. Chagnon; W.D. Cotton; C. Dominik; C.P. Dullemond; A.W. Glazenborg-Kluttig; A. Glindemann; T. Henning; K.-H. Hofmann; J. de Jong; R. Lenzen; S. Ligori; B. Lopez; J. Meisner; S. Morel; F. Paresce; J.-W. Pel; I. Percheron; G. Perrin; F. Przygodda; A. Richichi; M. Schöller; P. Schuller; B. Stecklum; M.E. van den Ancker; O. von der Lühe; G. Weigelt
2004-01-01
We present the first long baseline mid-infrared interferometric observations of the circumstellar disks surrounding Herbig Ae/Be stars. The observations were obtained using the mid-infrared interferometric instrument MIDI at the European Southern Observatory (ESO) Very Large Telescope Interferometer
19. First discovery of a magnetic field in a main sequence delta Scuti star: the Kepler star HD188774
CERN Document Server
Neiner, Coralie
2015-01-01
The Kepler space mission provided a wealth of {\\delta} Sct-{\\gamma} Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related surface inhomogeneities. In particular, the Kepler {\\delta} Sct-{\\gamma} Dor hybrid candidate HD 188774 shows a few low frequencies in its light and radial velocity curves, whose origin is unclear. In this work, we check for the presence of a magnetic field in HD 188774. We obtained two spectropolarimetric measurements with ESPaDOnS at CFHT. The data were analysed with the least squares deconvolution method. We detected a clear magnetic signature in the Stokes V LSD profiles. The origin of the low frequencies detected in HD 188774 is therefore most probably the rotational modulation of surface spots possibly related to the presence of a magnetic field. Consequently, HD 188774 is not a genuine hybrid {\\delta} Sct-{\\gamma} Dor star, but the first known magne...
20. MOST discovers a multimode delta Scuti star in a triple system: HD 61199
CERN Document Server
Hareter, M; Lehmann, H; Tsymbal, V; Hüber, D; Lenz, P; Weiss, W W; Matthews, J M; Rucinski, S; Rowe, J F; Kuschnig, R; Günther, D B; Moffat, A F J; Sasselov, D; Walker, G A H; Scholtz, A
2008-01-01
A field star, HD 61199 (V ~ 8), simultaneously observed with Procyon by the MOST (Microvariability & Oscillations of STars) satellite in continuous runs of 34, 17, and 34 days in 2004, 2005, and 2007, was found to pulsate in 11 frequencies in the delta Scuti range with amplitudes from 1.7 down to 0.09 mmag. The photometry also showed variations with a period of about four days. To investigate the nature of the longer period, 45 days of time-resolved spectroscopy was obtained at the Thueringer Landessternwarte Tautenburg in 2004. The radial velocity measurements indicate that HD 61199 is a triple system. A delta Scuti pulsator with a rich eigenspectrum in a multiple system is promising for asteroseismology. Our objectives were to identify which of the stars in the system is the delta Scuti variable and to obtain the orbital elements of the system and the fundamental parameters of the individual components, which are constrained by the pulsation frequencies of the delta Scuti star. Classical Fourier techniq...
1. The nature of the light variability of magnetic Of?p star HD 191612
CERN Document Server
Krticka, J
2016-01-01
A small fraction of hot OBA stars host global magnetic fields with field strengths of the order of 0.1-10 kG. This leads to the creation of persistent surface structures (spots) in stars with sufficiently weak winds as a result of the radiative diffusion. These spots become evident in spectroscopic and photometric variability. This type of variability is not expected in stars with strong winds, where the wind inhibits the radiative diffusion. Therefore, a weak photometric variability of the magnetic Of?p star HD 191612 is attributed to the light absorption in the circumstellar clouds. We study the nature of the photometric variability of HD 191612. We assume that the variability results from variable wind blanketing induced by surface variations of the magnetic field tilt and modulated by stellar rotation. We used our global kinetic equilibrium (NLTE) wind models with radiative force determined from the radiative transfer equation in the comoving frame (CMF) to predict the stellar emergent flux. Our models de...
2. The magnetic field topology and chemical abundance distributions of the Ap star HD 32633
CERN Document Server
2015-01-01
Previous observations of the Ap star HD 32633 indicated that its magnetic field was unusually complex in nature and could not be characterised by a simple dipolar structure. Here we derive magnetic field maps and chemical abundance distributions for this star using full Stokes vector (Stokes $IQUV$) high-resolution observations obtained with the ESPaDOnS and Narval spectropolarimeters. Our maps, produced using the Invers10 magnetic Doppler imaging (MDI) code, show that HD 32633 has a strong magnetic field which features two large regions of opposite polarity but deviates significantly from a pure dipole field. We use a spherical harmonic expansion to characterise the magnetic field and find that the harmonic energy is predominately in the $\\ell=1$ and $\\ell=2$ poloidal modes with a small toroidal component. At the same time, we demonstrate that the observed Stokes parameter profiles of HD 32633 cannot be fully described by either a dipolar or dipolar plus quadrupolar field geometry. We compare the magnetic fi...
3. Testing stellar evolution models with the retired A star HD 185351
Science.gov (United States)
Hjørringgaard, J. G.; Silva Aguirre, V.; White, T. R.; Huber, D.; Pope, B. J. S.; Casagrande, L.; Justesen, A. B.; Christensen-Dalsgaard, J.
2016-10-01
The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. (2014) using interferometry, spectroscopy and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of 1.5M⊙. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from ˜1.6 - 1.9M⊙ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as considering the additional constraint of the observed g-mode period spacing. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the overshooting efficiency using low-luminosity red giant stars. A theoretical model with metallicity [Fe/H] = 0.16dex, mixing-length parameter αMLT = 2.00, and convective overshooting efficiency parameter f = 0.030 is found to be in complete agreement with all observational constraints for a stellar mass of M ≃ 1.60M⊙.
4. Temperaments of young stars: Rapid mass-accretion rate changes in T Tauri and Herbig Ae stars
CERN Document Server
Costigan, Gráinne; Scholz, Aleks; Ray, Tom; Testi, Leonardo
2014-01-01
Variability in emission lines is a characteristic feature in young stars and can be used as a tool to study the physics of the accretion process. Here we present a study of H{\\alpha} variability in 15 T Tauri and Herbig Ae stars (K7-B2) over a wide range of time windows, from minutes, to hours, to days, and years. We assess the variability using linewidth measurements and the time series of line profiles. All objects show gradual, slow profile changes on time-scales of days. In addition, in three cases there is evidence for rapid variations in H{\\alpha} with typical time-scales of 10 min, which occurs in 10% of the total covered observing time. The mean accretion-rate changes, inferred from the line fluxes,are 0.01-0.07 dex for time-scales of < 1 hour, 0.04-0.4 dex for time-scales of days, and 0.13-0.52 dex for time-scales of years. In Costigan et al. 2012 we derived an upper limit finding that the intermediate (days) variability dominated over longer (years) variability. Here our new results, based on muc...
5. Elodie metallicity-biased search for transiting Hot Jupiters I. Two Hot Jupiters orbiting the slightly evolved stars HD118203 and HD149143
OpenAIRE
da Silva, R.; Udry, S.; Bouchy, F.; Mayor, M.; Moutou, C.; Pont, F.; Queloz, D.; Santos, N.C.; Segransan, D.; Zucker, S.
2005-01-01
We report the discovery of a new planet candidate orbiting the subgiant star HD118203 with a period of P=6.1335 days. The best Keplerian solution yields an eccentricity e=0.31 and a minimum mass m2sin(i)=2.1MJup for the planet. This star has been observed with the ELODIE fiber-fed spectrograph as one of the targets in our planet-search programme biased toward high-metallicity stars, on-going since March 2004 at the Haute-Provence Observatory. An analysis of the spectroscopic line profiles usi...
6. HD 179821 (V1427 Aql, IRAS 19114+0002) - a massive post-red supergiant star?
Science.gov (United States)
Şahin, T.; Lambert, David L.; Klochkova, Valentina G.; Panchuk, Vladimir E.
2016-10-01
We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe] = 1.0 ± 0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H] = 0.4 dex places it among the most metal-rich stars yet analysed. The abundance analysis of this luminous star is based on high-resolution and high-quality (S/N ≈ 120-420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over 21 epochs. Standard 1D local thermodynamic equilibrium analysis provides a fresh determination of the atmospheric parameters over all epochs: Teff = 7350 ± 200 K, log g= +0.6 ± 0.3, and a microturbulent velocity ξ = 6.6 ± 1.6 km s-1 and [Fe/H] = 0.4 ± 0.2, and a carbon abundance [C/Fe] = -0.19 ± 0.30. We find oxygen abundance [O/Fe] = -0.25 ± 0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 ± 2.0 km s-1 is determined from both strong and weak Fe I and Fe II lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] ≈ 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for H α line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.
7. The color dependent morphology of the post-AGB star HD 161796
Science.gov (United States)
Min, M.; Jeffers, S. V.; Canovas, H.; Rodenhuis, M.; Keller, C. U.; Waters, L. B. F. M.
2013-06-01
Context. Many protoplanetary nebulae show strong asymmetries in their surrounding shells, pointing to asymmetries during the mass loss phase. Questions concerning the origin and the onset of deviations from spherical symmetry are important for our understanding of the evolution of these objects. Here we focus on the circumstellar shell of the post-AGB star HD 161796. Aims: We aim to detect signatures of an aspherical outflow, and to derive its properties. Methods: We used the imaging polarimeter the Extreme Polarimeter (ExPo), a visitor instrument at the William Herschel Telescope, to accurately image the dust shell surrounding HD 161796 in various wavelength filters. Imaging polarimetry allows us to separate the faint, polarized, light that comes from circumstellar material from the bright, unpolarized, light from the central star. Results: The shell around HD 161796 is highly aspherical. A clear signature of an equatorial density enhancement can be seen. This structure is optically thick at short wavelengths and changes its appearance to optically thin at longer wavelengths. In the classification of the two different appearances of planetary nebulae from HST images it changes from being classified as DUst-Prominent Longitudinally-EXtended (DUPLEX) at short wavelengths to star-obvious low-level-elongated (SOLE) at longer wavelengths. This strengthens the interpretation that these two appearances are manifestations of the same physical structure. Furthermore, we find that the central star is hotter than often assumed and the relatively high observed reddening is a consequence of circumstellar rather than interstellar extinction. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsicaŋsica de Canarias.
8. Model atmospheres of magnetic chemically peculiar stars. A remarkable strong-field Bp SiCrFe star HD137509
CERN Document Server
Shulyak, Denis; Khan, Sergiy
2008-01-01
In the last few years we have developed stellar model atmospheres which included effects of anomalous abundances and strong magnetic field. The full treatment of anomalous Zeeman splitting and polarized radiative transfer were introduced in the model atmosphere calculations for the first time. In this investigation we present results of modelling the atmosphere of one of the most extreme magnetic chemically peculiar stars, HD137509. This Bp SiCrFe star has the mean surface magnetic field modulus of about 29kG. We use the recent version of the line-by-line opacity sampling stellar model atmosphere code LLmodels, which incorporates the full treatment of Zeeman splitting of spectral lines, detailed polarized radiative transfer and arbitrary abundances. We compare model predictions with photometric and spectroscopic observations of the star, aiming to reach a self-consistency between the abundance pattern derived from high-resolution spectra and abundances used for model atmosphere calculation. Based on magnetic ...
9. Non-radial pulsations in the extreme helium star HD 160641
International Nuclear Information System (INIS)
Mean periods of 0.35 +- 0.01, 0.71 +- 0.05, 1.12 +- 0.13 and 1.77 +-0.34 day are identified from separately analysed photometric observations (obtained in 1979 and 1982) of the extreme helium star HD 160641. Radial velocities were obtained simultaneously with photometry on three nights in 1982. Optical variations are not accompanied by detectable colour changes, and radial velocities are not characteristic of radial pulsation. HD 160641 is therefore regarded as a non-radial pulsator. Radial velocity and light variations are tentatively interpreted as l = 4 mode pulsation, corresponding to a Wesselink radius of 7.9 +- 1.0 solar radii. (author)
10. Non-radial pulsations in the extreme helium star HD 160641
Energy Technology Data Exchange (ETDEWEB)
Lynas-Gray, A.E.; Kilkenny, D.; Skillen, I.; Jeffery, C.S.
1987-08-15
Mean periods of 0.35 +- 0.01, 0.71 +- 0.05, 1.12 +- 0.13 and 1.77 +-0.34 day are identified from separately analysed photometric observations (obtained in 1979 and 1982) of the extreme helium star HD 160641. Radial velocities were obtained simultaneously with photometry on three nights in 1982. Optical variations are not accompanied by detectable colour changes, and radial velocities are not characteristic of radial pulsation. HD 160641 is therefore regarded as a non-radial pulsator. Radial velocity and light variations are tentatively interpreted as l = 4 mode pulsation, corresponding to a Wesselink radius of 7.9 +- 1.0 solar radii.
11. Determining the atmospheric structure and dynamics of the FK Comae Star HD32918
Science.gov (United States)
Robinson, R. D.
1995-01-01
The results of UV observations taken with the International Ultraviolet Explorer (IUE) satellite and microwave observations obtained with the Australia Telescope during an observing campaign of the rapidly rotating K0 dwarf star HD 197890, nicknamed 'Speedy Mic' are presented. This star was recently recognized as a powerful, transient EUV source by the ROSAT WFC, and subsequent investigation showed it to be a ZAMS or possibly a PMS dwarf which may be a member of the Local Association. Our observations show it to have strong, variable UV emission lines near the 'saturation' levels. The radio observations show a level of 'quiescent' emission consistent with other rapidly rotating stars, but there is no evidence for the large flux variations that normally characterize the time history of such objects.
12. The classification of frequencies in the {\\gamma} Doradus / {\\delta} Scuti hybrid star HD 49434
CERN Document Server
Brunsden, E; Cottrell, P L; Uytterhoeven, K; Wright, D J; De Cat, P
2014-01-01
Hybrid stars of the {\\gamma} Doradus and {\\delta} Scuti pulsation types have great potential for asteroseismic analysis to explore their interior structure. To achieve this, mode identi- fications of pulsational frequencies observed in the stars must be made, a task which is far from simple. In this work we begin the analysis by scrutinizing the frequencies found in the CoRoT photometric satellite measurements and ground-based high-resolution spectroscopy of the hybrid star HD 49434. The results show almost no consistency between the frequencies found using the two techniques and no characteristic period spacings or couplings were identified in either dataset. The spectroscopic data additionally show no evidence for any long term (5 year) variation in the dominant frequency. The 31 spectroscopic frequencies identified have standard deviation profiles suggesting multiple modes sharing (l, m) in the {\\delta} Scuti frequency region and several skewed modes sharing the same (l, m) in the {\\gamma} Doradus frequenc...
13. A NEW SUB-STELLAR COMPANION AROUND THE YOUNG STAR HD 284149
Energy Technology Data Exchange (ETDEWEB)
Bonavita, Mariangela; Desidera, Silvano [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Daemgen, Sebastian; Jayawardhana, Ray [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada); Janson, Markus [Astrophysics Research Centre, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Lafrenière, David, E-mail: mariangela.bonavita@oapd.inaf.it [Department of Physics, University of Montreal, Montreal, QC H3T 1J4 (Canada)
2014-08-20
Even though only a handful of sub-stellar companions have been found via direct imaging, each of these discoveries has had a tremendous impact on our understanding of the star formation process and the physics of cool atmospheres. Young stars are prime targets for direct imaging searches for planets and brown dwarfs due to the favorable brightness contrast expected at such ages and also because it is often possible to derive relatively good age estimates for these primaries. Here we present the direct imaging discovery of HD 284149 b, a 18-50 M {sub Jup} companion at a projected separation of 400 AU from a young (25{sub 10}{sup +25} Myr) F8 star, with which it shares common proper motion.
14. HD 41641: a classical $\\delta$ Sct-type pulsator with chemical signatures of an Ap star
CERN Document Server
Escorza, A; Tkachenko, A; Van Reeth, T; Ryabchikova, T; Neiner, C; Poretti, E; Rainer, M; Michel, E; Baglin, A; Aerts, C
2016-01-01
Among the known groups of pulsating stars, $\\delta$ Sct stars are one of the least understood. The theoretical models do not predict the oscillation frequencies that observations reveal. Complete asteroseismic studies are necessary to improve these models and better understand the internal structure of these targets. In this paper, we study the $\\delta$ Sct star HD 41641 with the ultimate goal of understanding its oscillation pattern. The target has been simultaneously observed by the CoRoT space telescope and the HARPS high-resolution spectrograph. The photometric data set was analyzed with the software package PERIOD04, while FAMIAS was used to analyze the line profile variations. The method of spectrum synthesis was used for spectroscopically determining the fundamental atmospheric parameters and the individual chemical abundances. A total of 90 different frequencies was identified and analyzed. An unambiguous identification of the azimuthal order of the surface geometry could be provided for the dominant ...
15. The Gemini NICI Planet-Finding Campaign: Discovery of a Multiple System Orbiting the Young A Star HD 1160
CERN Document Server
Nielsen, Eric L; Wahhaj, Zahed; Biller, Beth A; Hayward, Thomas L; Boss, Alan; Bowler, Brendan; Kraus, Adam; Shkolnik, Evgenya L; Tecza, Matthias; Chun, Mark; Clarke, Fraser; Close, Laird M; Ftaclas, Christ; Hartung, Markus; Males, Jared R; Reid, I Neill; Skemer, Andrew J; Alencar, Silvia H P; Burrows, Adam; Pino, Elisabethe de Gouveia Dal; Gregorio-Hetem, Jane; Kuchner, Marc; Thatte, Niranjan; Toomey, Douglas W
2012-01-01
We report the discovery by the Gemini NICI Planet-Finding Campaign of two low-mass companions to the young A0V star HD 1160 at projected separations of 81 +/- 5 AU (HD 1160 B) and 533 +/- 25 AU (HD 1160 C). VLT images of the system taken over a decade for the purpose of using HD 1160 A as a photometric calibrator confirm that both companions are physically associated. By comparing the system to members of young moving groups and open clusters with well-established ages, we estimate an age of 50 (+50,-40) Myr for HD 1160 ABC. While the UVW motion of the system does not match any known moving group, the small magnitude of the space velocity is consistent with youth. Near-IR spectroscopy shows HD 1160 C to be an M3.5 +/- 0.5 star with an estimated mass of 0.22 (+0.03,-0.04) M_Sun, while NIR photometry of HD 1160 B suggests a brown dwarf with a mass of 33 (+12,-9) M_Jup. The very small mass ratio (0.014) between the A and B components of the system is rare for A star binaries, and would represent a planetary-mass...
16. A 12-year Activity Cycle for the Nearby Planet Host Star HD 219134
Science.gov (United States)
Johnson, Marshall C.; Endl, Michael; Cochran, William D.; Meschiari, Stefano; Robertson, Paul; MacQueen, Phillip J.; Brugamyer, Erik J.; Caldwell, Caroline; Hatzes, Artie P.; Ramírez, Ivan; Wittenmyer, Robert A.
2016-04-01
The nearby (6.5 pc) star HD 219134 was recently shown by Motalebi et al. and Vogt et al. to host several planets, the innermost of which is transiting. We present 27 years of radial velocity (RV) observations of this star from the McDonald Observatory Planet Search program, and 19 years of stellar activity data. We detect a long-period activity cycle measured in the Ca ii SHK index, with a period of 4230 ± 100 days (11.7 years), very similar to the 11 year solar activity cycle. Although the period of the Saturn-mass planet HD 219134 h is close to half that of the activity cycle, we argue that it is not an artifact due to stellar activity. We also find a significant periodicity in the SHK data due to stellar rotation with a period of 22.8 days. This is identical to the period of planet f identified by Vogt et al., suggesting that this RV signal might be caused by rotational modulation of stellar activity rather than a planet. Analysis of our RVs allows us to detect the long-period planet HD 219134 h and the transiting super-Earth HD 219134 b. Finally, we use our long time baseline to constrain the presence of longer period planets in the system, excluding to 1σ objects with M{sin}i\\gt 0.36{M}J at 12 years (corresponding to the orbital period of Jupiter) and M{sin}i\\gt 0.72{M}J at a period of 16.4 years (assuming a circular orbit for an outer companion).
17. VizieR Online Data Catalog: HST photometry of stars in HD 97950 (Pang+, 2016)
Science.gov (United States)
Pang, X.; Pasquali, A.; Grebel, E. K.
2016-07-01
The HD97950 cluster and its immediate surroundings in the giant HII region NGC3603 were observed with the Hubble Space Telescope (HST). The ultraviolet (UV) data were taken with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in 2005 (GO 10602, PI: Jesus Maiz Apellaniz) through the F220W, F250W, F330W, and F435W filters. The HRC is characterized by a spatial resolution of 0.03"/pixel and a field of view of 29''*25''. The optical observations were carried out with the Wide Field and Planetary Camera 2 (WFPC2) in two epochs: 1997 (GO 6763, PI: Laurent Drissen) and 2007 (GO 11193, PI: Wolfgang Brandner) through the F555W, F675W, and F814W filters. The Planetary Camera (PC) chip was centered on the cluster (0.045"/pixel, 40''*40'') for both programs. Pang et al. 2013 (cat. J/ApJ/764/73) reduced the two-epoch WFPC2 data and identified more than 400 member stars on the PC chip via relative proper motions. Of these member stars, 142 are in common between the HRC and PC images and thus have UV and optical photometry available (see Table1). Among the HD97950 cluster member stars determined from relative proper motions (Pang et al. 2013, cat. J/ApJ/764/73, Table2), there are five main-sequence (MS) stars located in the cluster with projected distances of r<0.7pc from the center, for which there are also spectral types available from Table3 of Melena et al. (2008AJ....135..878M). The photometry of these five MS stars is presented in Table2. The individual color excesses and extinctions of the member main sequence stars are listed in Table3. (3 data files).
18. The complex circumstellar environment of HD142527
CERN Document Server
Verhoeff, A P; Pantin, E; Waters, L B F M; Tielens, A G G M; Honda, M; Fujiwara, H; Bouwman, J; van Boekel, R; Dougherty, S M; de Koter, A; Dominik, C; Mulders, G D
2011-01-01
The recent findings of gas giant planets around young A-type stars suggest that disks surrounding Herbig Ae/Be stars will develop planetary systems. An interesting case is HD142527, for which previous observations revealed a complex circumstellar environment and an unusually high ratio of infrared to stellar luminosity. Its properties differ considerably from other Herbig Ae/Be stars. This suggests that the disk surrounding HD142527 is in an uncommon evolutionary stage. We aim for a better understanding of the geometry and evolutionary status of the circumstellar material around the Herbig Ae/Be star HD142527. We map the composition and spatial distribution of the dust around HD142527. We analyze SEST and ATCA millimeter data, VISIR N and Q-band imaging and spectroscopy. We gather additional relevant data from the literature. We use the radiative transfer code MCMax to construct a model of the geometry and density structure of the circumstellar matter, which fits all of the observables satisfactorily. We find...
19. Diamonds in HD 97048
CERN Document Server
Habart, E; Natta, A; Carbillet, M
2004-01-01
We present adaptive optics high angular resolution ($\\sim0\\farcs$1) spectroscopic observations in the 3 $\\mu$m region of the Herbig Ae/Be star HD 97048. For the first time, we spatially resolve the emission in the diamond features at 3.43 and 3.53 $\\mu$m and in the adjacent continuum. Using both the intensity profiles along the slit and reconstructed two-dimensional images of the object, we derive full-width at half-maximum sizes consistent with the predictions for a circumstellar disk seen pole-on. The diamond emission originates in the inner region ($R \\lesssim 15$ AU) of the disk.
20. Searching for Star-Planet interactions within the magnetosphere of HD 189733
CERN Document Server
Fares, R; Moutou, C; Jardine, M M; Griessmeier, J -M; Zarka, P; Shkolnik, E L; Bohlender, D; Catala, C; Cameron, A C
2010-01-01
HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (June 2007 and July 2008). HD 189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40 G. The star is differentially rotating, with latitudinal angular velocity shear of domega = 0.146 +- 0.049 rad/d, corresponding to equatorial and polar periods of 11.94 +- 0.16 d and 16.53 +- 2.43 d respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric int...
1. Vertical abundance stratification in the blue horizontal branch star HD135485
CERN Document Server
Khalack, V R; Bohlender, D A; Wade, G A; Behr, B B
2007-01-01
It is commonly believed that the observed overabundances of many chemical species relative to the expected cluster metallicity in blue horizontal branch (BHB) stars appear as a result of atomic diffusion in the photosphere. The slow rotation of BHB stars (with T_eff > 11,500K), typically v sin{i} < 10 km/s, is consistent with this idea. In this work we search for observational evidence of vertical chemical stratification in the atmosphere of HD135485. If this evidence exists, it will demonstrate the importance of atomic diffusion processes in the atmospheres of BHB stars. We undertake an extensive abundance stratification analysis of the atmosphere of HD135485, based on recently acquired high resolution and S/N CFHT ESPaDOnS spectra and a McDonald-CE spectrum. Our numerical simulations show that nitrogen and sulfur reveal signatures of vertical abundance stratification in the stellar atmosphere. It appears that the abundances of these elements increase toward the upper atmosphere. This fact cannot be expla...
2. Iron-Group Abundances in the Metal-Poor Main Sequence Turnoff Star HD~84937
CERN Document Server
Sneden, Christopher; Kobayashi, Chiaki; Pignatari, Marco; Lawler, James E; Hartog, Elizabeth A Den; Wood, Michael P
2015-01-01
We have derived new very accurate abundances of the Fe-group elements Sc through Zn (Z = 21-30) in the bright main-sequence turnoff star HD 84937, based on high-resolution spectra covering the visible and ultraviolet spectral regions. New or recent laboratory transition data for 14 species of seven elements have been used. Abundances from more than 600 lines of non-Fe species have been combined with about 550 Fe lines in HD 84937 to yield abundance ratios of high precision. The abundances have been determined from both neutral and ionized transitions, which generally are in agreement with each other. We find no substantial departures from standard LTE Saha ionization balance in this [Fe/H] = -2.32 star. Noteworthy among the abundances are: [Co/Fe] = 0.14 and [Cu/Fe] = -0.83, in agreement with past studies abundance trends in this and other low metallicity stars; and = 0.31, which has not been noted previously. A detailed examination of scandium, titanium, and vanadium abundances in large-sample spectroscopic...
3. A resolved debris disk around the candidate planet-hosting star HD95086
CERN Document Server
Moór, A; Kóspál, Á; Szabó, Gy M; Apai, D; Balog, Z; Csengeri, T; Grady, C; Henning, Th; Juhász, A; Kiss, Cs; Pascucci, I; Szulágyi, J; Vavrek, R
2013-01-01
Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD95086. The strong infrared excess of the system indicates that, similarly to HR8799, {\\ss} Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD95086 disk, and to investigate its possible interaction with the newly discovered planet, here we present new optical, infrared and millimeter observations. We detected no CO emission, excluding the possibility of an evolved gaseous primordial disk. Simple blackbody modeling of the spectral energy distribution suggests the presence of two spatially separate dust belts at radial distances of 6 and 64 AU. Our resolved images obtained with the Herschel Space Observatory reveal a characteristic disk size of ~6.0x5.4 arcsec (540x490 AU) and disk inclination of ~25 degree. Assuming the same inclination for the planet candidate's orbit, its re-projected radial distance from the star is 62 AU, very close to th...
4. A Resolved Debris Disk Around the Candidate Planet-hosting Star HD 95086
Science.gov (United States)
Moor, A.; Abraham, P.; Kospal, A.; Szabo, Gy. M.; Apai, D.; Balog, Z.; Csengeri, T.; Grady, C.; Henning, Th.; Juhasz, J.; Kiss, Cs.; Pasucci, I.; Szulagyi, J.; Vavrek, R.
2013-01-01
Recently, a new planet candidate was discovered on direct images around the young (10-17 Myr) A-type star HD 95086. The strong infrared excess of the system indicates that, similar to HR8799, Beta Pic, and Fomalhaut, the star harbors a circumstellar disk. Aiming to study the structure and gas content of the HD 95086 disk, and to investigate its possible interaction with the newly discovered planet, here we present new optical, infrared, and millimeter observations. We detected no CO emission, excluding the possibility of an evolved gaseous primordial disk. Simple blackbody modeling of the spectral energy distribution suggests the presence of two spatially separate dust belts at radial distances of 6 and 64 AU. Our resolved images obtained with the Herschel Space Observatory reveal a characteristic disk size of approx. 6.0 × 5.4 (540 × 490 AU) and disk inclination of approx 25 deg. Assuming the same inclination for the planet candidate's orbit, its reprojected radial distance from the star is 62 AU, very close to the blackbody radius of the outer cold dust ring. The structure of the planetary system at HD 95086 resembles the one around HR8799. Both systems harbor a warm inner dust belt and a broad colder outer disk and giant planet(s) between the two dusty regions. Modeling implies that the candidate planet can dynamically excite the motion of planetesimals even out to 270 AU via their secular perturbation if its orbital eccentricity is larger than about 0.4. Our analysis adds a new example to the three known systems where directly imaged planet(s) and debris disks coexist.
5. Confirming HD 23478 as a new magnetic B star hosting an Hα-bright centrifugal magnetosphere
Science.gov (United States)
Sikora, J.; Wade, G. A.; Bohlender, D. A.; Neiner, C.; Oksala, M. E.; Shultz, M.; Cohen, D. H.; ud-Doula, A.; Grunhut, J.; Monin, D.; Owocki, S.; Petit, V.; Rivinus, T.; Townsend, R. H. D.
2015-08-01
In this paper, we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high-resolution Stokes V spectra using the ESPaDOnS (Canada-France-Hawaii Telescope) and Narval (Télescope Bernard Lyot) spectropolarimeters, and 11 from medium-resolution Stokes V spectra obtained with the DimaPol spectropolarimeter (Dominion Astronomical Observatory). HD 23478 was one of two rapidly rotating stars identified as potential centrifugal magnetosphere' hosts based on IR observations from the Apache Point Observatory Galactic Evolution Experiment survey. We derive basic physical properties of this star including its mass (M=6.1^{+0.8}_{-0.7} M_{⊙), effective temperature (Teff = 20 ± 2 kK), radius (R=2.7^{+1.6}_{-0.9} R_{⊙}), and age (τ_age=3^{+37}_{-1} Myr). We repeatedly detect weakly variable Zeeman signatures in metal, He, and H lines in all our observations corresponding to a longitudinal magnetic field of ≈ -2.0 kG. The rotational period is inferred from Hipparcos photometry (Prot = 1.0498(4) d). Under the assumption of the Oblique Rotator Model, our observations yield a surface dipole magnetic field of strength Bd ≥ 9.5 kG that is approximately aligned with the stellar rotation axis. We confirm the presence of strong and broad Hα emission and gauge the volume of this star's centrifugal magnetosphere to be consistent with those of other Hα emitting centrifugal magnetosphere stars based on the large inferred Alfvén to Kepler radius ratio.
6. Elemental abundances of the B and A stars. 2: Gamma Geminorum, HD 60825, 7 Sextantis, HR 4817, and HR 5780
Science.gov (United States)
Adelman, Saul J.; Philip, A. G. Davis
1994-01-01
We extend fine analyses of the B and A stars, gamma Geminorum, 7 Sextantis, HR 4817, and HR 5780 using additional spectroscopic data from the Kitt Peak National Observatory (KPNO) coude feed telescope with a TI CCD, camera 5, and grating A, and ATLAS9 model atmospheres. In addition we study HD 60825, which had colors similar to the FHB A stars, but was found to be a Population I star. HD 60825, as is gamma Gem, is a sharp-lined early-A star with nearly solar derived abundances. HR 5780 and 7 Sex are also examples of stars which for the most part have solar abundances. The newly derived abundances for HR 4817 reveal important differences with respect to 53 Tau, a somewhat similar HgMn star.
7. Testing stellar evolution models with the retired A star HD 185351
CERN Document Server
Hjørringgaard, Jakob G; White, Tim R; Huber, Daniel; Pope, Benjamin J S; Casagrande, Luca; Justesen, Anders B; Christensen-Dalsgaard, Jørgen
2016-01-01
The physical parameters of the retired A star HD 185351 were analysed in great detail by Johnson et al. (2014) using interferometry, spectroscopy and asteroseismology. Results from all independent methods are consistent with HD 185351 having a mass in excess of $1.5\\mathrm{M}_{\\odot}$. However, the study also showed that not all observational constraints could be reconciled in stellar evolutionary models, leading to mass estimates ranging from $\\sim 1.6-1.9\\mathrm{M}_{\\odot}$ and casting doubts on the accuracy of stellar properties determined from asteroseismology. Here we solve this discrepancy and construct a theoretical model in agreement with all observational constraints on the physical parameters of HD 185351. The effects of varying input physics are examined as well as considering the additional constraint of the observed g-mode period spacing. This quantity is found to be sensitive to the inclusion of additional mixing from the convective core during the main sequence, and can be used to calibrate the...
8. Multiwavelength study of the magnetically active T Tauri star HD 283447
Science.gov (United States)
Feigelson, Eric D.; Welty, Alan D.; Imhoff, Catherine; Hall, Jeffrey C.; Etzel, Paul B.; Phillips, Robert B.; Lonsdale, Colin J.
1994-01-01
We observed the luminous T Tauri star HD 283447 = V773 Tauri simultaneously at X-ray, ultraviolet, optical photometric and spectroscopic, and radio wavelengths for several hours on UT 1992 September 11. ROSAT, IUE, Very Large Array (VLA) and an intercontinental Very Long Baseline Interferometry (VLBI) network, and three optical observatories participated in the campaign. The star is known for its unusually high and variable nonthermal radio continuum emission. High levels of soft X-ray and Mg II line emission are discovered, with luminosity L(sub x) = 5.5 x 10(exp 30) ergs/s (0.2 - 2 keV) and L(sub Mg II) = 1 x 10(exp 29) ergs/s, respectively. Optically, the spectrum exhibits rather weak characteristics of classical' T Tauri stars. A faint, broad emission line component, probably due to a collimated wind or infall, is present. During the campaign, the radio luminosity decreased by a factor of 4, while optical/UV lines and X-ray emission remained strong but constant. The large gyrosynchrotron-emitting regions are therefore decoupled from the chromospheric and coronal emission. Five models for the magnetic geometry around the star are discussed; solar-type activity, dipole magnetosphere, star-disk magnetic coupling, disk magnetic fields, and close binary interaction. The data suggest that two magnetic geometries are simultaneously present: complex multipolar fields like those on the Sun, and a large-scale field possibly associated with the circumstellar disk.
9. The Cool Giant HD 77361 - A Super Li-Rich Star
CERN Document Server
Lyubimkov, L S; Metlov, V G; Pavlenko, Ya V; Poklad, D B; Rachkovskaya, T M
2016-01-01
Super Li-rich stars form a very small and enigmatic group whose existence cannot be explained in terms of the standard stellar evolution theory. The goal of our study is to check the reality of this group of cool giants based on an independent technique. We have carried out such a check using the K giant HD 77361 (HR 3597), which has previously been assigned to this rare type, as an example. We have redetermined the effective temperature Teff and surface gravity log g for this star. We have applied two different methods, photometric and spectroscopic, to estimate Teff (the accuracy of the Li-abundance determination depends significantly on this parameter). The value of log g has been found from the highly accurate parallax of this nearby star. To apply the photometric method of determining Teff, we have performed UBV observations of the star, which yielded V = 6.18 +/- 0.03, B - V = 1.13 +/- 0.01, and U - B = 1.18+/-0.05. The following parameters of the star have been found: effective temperature Teff = 4370+...
10. The role of turbulent pressure as a coherent pulsational driving mechanism: the case of the delta Scuti star HD 187547
CERN Document Server
Antoci, V; Houdek, G; Kjeldsen, H; Trampedach, R; Handler, G; Lueftinger, T; Arentoft, T; Murphy, S
2014-01-01
HD 187547 was the first candidate that led to the suggestion that solar-like oscillations are present in delta Scuti stars. Longer observations, however, show that the modes interpreted as solar-like oscillations have either very long mode lifetimes, longer than 960 days, or are coherent. These results are incompatible with the nature of pure' stochastic excitation as observed in solar-like stars. Nonetheless, one point is certain: the opacity mechanism alone cannot explain the oscillation spectrum of HD 187547. Here we present new theoretical investigations showing that convection dynamics can intrinsically excite coherent pulsations in the chemically peculiar delta Scuti star HD 187547. More precisely, it is the perturbations of the mean Reynold stresses (turbulent pressure) that drives the pulsations and the excitation takes place predominantly in the hydrogen ionization zone.
11. Confirmation of the magnetic oblique rotator model for the Of?p star HD 191612
CERN Document Server
Wade, G A; Townsend, R H D; Grunhut, J H; Shultz, M; Bouret, J -C; Fullerton, A; Marcolino, W; Martins, F; Nazé, Y; Doula, A ud; Walborn, N R; Donati, J -F
2011-01-01
This paper reports high-precision Stokes V spectra of HD 191612 acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, in the context of the Magnetism in Massive stars (MiMeS) Project. Using measurements of the equivalent width of the Halpha line and radial velocities of various metallic lines, we have updated both the spectroscopic and orbital ephemerides of this star. We confirm the presence of a strong magnetic field in the photosphere of HD 191612, and detect its variability. We establish that the longitudinal field varies in a manner consistent with the spectroscopic period of 537.6 d, in an approximately sinusoidal fashion. This demonstrates a firm connection between the magnetic field and the processes responsible for the line and continuum variability. Interpreting the variation of the longitudinal magnetic field within the context of the dipole oblique rotator model we obtain a best-fit surface magnetic field model with obliquity beta=67\\pm 5 deg and polar strength Bd=2...
12. The spectral variability and magnetic field characteristics of the Of?p star HD 148937
CERN Document Server
Wade, G A; Graefener, G; Howarth, I D; Martins, F; Petit, V; Vink, J S; Bagnulo, S; Folsom, C P; Nazé, Y; Walborn, N R; Townsend, R H D; Evans, C J
2011-01-01
We reportmagnetic and spectroscopic observations and modeling of the Of?p star HD 148937 within the context of theMagnetism in Massive Stars (MiMeS) Large Program at the Canada-France-Hawaii Telescope. Thirty-two high signal-to-noise ratio circularly polarised (Stokes V) spectra and 13 unpolarised (Stokes I) spectra of HD 148937 were acquired in 2009 and 2010. A definite detection of a Stokes V Zeeman signature is obtained in the grand mean of all observations (in both Least-Squares Deconvolved (LSD) mean profiles and individual spectral lines). The longitudinalmagnetic field inferred from the Stokes V LSD profiles is consistently negative, in contrast to the essentially zero field strength measured from the diagnostic null profiles. A period search of new and archival equivalent width measurements confirms the previously-reported 7.03 d variability period. The variation of equivalent widths is not strictly periodic: we present evidence for evolution of the amount or distribution of circumstellar plasma. Inte...
13. Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682
CERN Document Server
Grunhut, J H; Sundqvist, J O; ud-Doula, A; Neiner, C; Ignace, R; Marcolino, W L F; Rivinius, Th; Fullerton, A; Kaper, L; Mauclaire, B; Buil, C; Garrel, T; Ribeiro, J; Ubaud, S
2012-01-01
The O9IV star HD 57682, discovered to be magnetic within the context of the MiMeS survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, the MiMeS Collaboration has continued to obtain spectroscopic and magnetic observations in order to refine our knowledge of its magnetic field strength and geometry, rotational period, and spectral properties and variability. In this paper we report new ESPaDOnS spectropolarimetric observations of HD 57682, which are combined with previously published ESPaDOnS data and archival H{\\alpha} spectroscopy. This dataset is used to determine the rotational period (63.5708 \\pm 0.0057 d), refine the longitudinal magnetic field variation and magnetic geometry (dipole surface field strength of 880\\pm50 G and magnetic obliquity of 79\\pm4\\circ as measured from the magnetic longitudinal field variations, assuming an inclination of 60\\circ), and examine the p...
14. High-resolution X-ray spectroscopy of the magnetic Of?p star HD148937
CERN Document Server
Naze, Y; Walborn, N R
2011-01-01
High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800km/s), i.e. narrower than the O line recorded by RGS, which possibly indicates that the hot plasma is multi-thermal and has several origins. These data further indicate a main plasma temperature of about 0.6keV and a formation of the X-ray emission at about one stellar radius above the photosphere. From the spectral fits and the H-to-He line ratios, the presence of very hot plasma is however confirmed, though with a smaller relative strength than for the prototype magnetic oblique rotator $\\theta^1$\\,Ori\\,C. Both stars thus share many similarities, but HD148937 appears less extreme than $\\theta^1$\\,Ori\\,C despite having also a large magnetic confinement parameter.
15. Gas and dust spectra of the D' type symbiotic star HD330036
CERN Document Server
Angeloni, R; Ciroi, S; Rafanelli, P
2007-01-01
We present a comprehensive and self-consistent modelling of the D' type symbiotic star (SS) HD330036 from radio to UV. Within a colliding-wind scenario, we analyse the continuum, line and dust spectra by means of SUMA, a code that simulates the physical conditions of an emitting gaseous cloud under the coupled effect of ionization from an external radiation source and shocks. We find that the UV lines are emitted from high density gas between the stars downstream of the reverse shock, while the optical lines are emitted downstream of the shock propagating outwards the system. As regards with the continuum SED, three shells are identified in the IR, at 850K, 320 K and 200 K with radii r = 2.8 10^13 cm, 4 10^14$cm, and 10^15 cm, respectively, adopting a distance to Earth d=2.3 kpc: interestingly, all these shells appear to be circumbinary. The analysis of the unexploited ISO-SWS spectrum reveals that both PAHs and crystalline silicates coexist in HD330036, with PAHs associated to the internal shell at 850 K, a... 16. Coordinated X-ray and Optical observations of Star-Planet Interaction in HD 17156 CERN Document Server Maggio, A; Scandariato, G; Lanza, A F; Sciortino, S; Borsa, F; Bonomo, A S; Claudi, R; Covino, E; Desidera, S; Gratton, R; Micela, G; Pagano, I; Piotto, G; Sozzetti, A; Cosentino, R; Maldonado, J 2015-01-01 The large number of close-in Jupiter-size exoplanets prompts the question whether star-planet interaction (SPI) effects can be detected. We focused our attention on the system HD 17156, having a Jupiter-mass planet in a very eccentric orbit. Here we present results of the XMM-Newton observations and of a five month coordinated optical campaign with the HARPS-N spectrograph. We observed HD 17156 with XMM-Newton when the planet was approaching the apoastron and then at the following periastron passage, quasi simultaneously with HARPS-N. We obtained a clear ($\\approx 5.5\\sigma$) X-ray detection only at the periastron visit, accompanied by a significant increase of the$R'_{\\rm HK}$chromospheric index. We discuss two possible scenarios for the activity enhancement: magnetic reconnection and flaring or accretion onto the star of material tidally stripped from the planet. In any case, this is possibly the first evidence of a magnetic SPI effect caught in action. 17. High-contrast imaging constraints on gas giant planet formation - The Herbig Ae/Be star opportunity CERN Document Server Quanz, Sascha P 2015-01-01 Planet formation studies are often focused on solar-type stars, implicitly considering our Sun as reference point. This approach overlooks, however, that Herbig Ae/Be stars are in some sense much better targets to study planet formation processes empirically, with their disks generally being larger, brighter and simply easier to observe across a large wavelength range. In addition, massive gas giant planets have been found on wide orbits around early type stars, triggering the question if these objects did indeed form there and, if so, by what process. In the following I briefly review what we currently know about the occurrence rate of planets around intermediate mass stars, before discussing recent results from Herbig Ae/Be stars in the context of planet formation. The main emphasis is put on spatially resolved polarized light images of potentially planet forming disks and how these images - in combination with other data - can be used to empirically constrain (parts of) the planet formation process. Of par... 18. NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii DEFF Research Database (Denmark) Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.; 2014-01-01 AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations of t... 19. Abundances of neutron-capture elements in the Hot Extreme-Helium Stars V1920 Cygni and HD 124448 CERN Document Server Pandey, G; Rao, N K; Jeffery, C S; Pandey, Gajendra; Lambert, David L. 2004-01-01 Analysis of HST STIS ultraviolet spectra of two hot extreme helium stars (EHes): V1920 Cyg and HD 124448 provide the first measurements of abundances of neutron-capture elements for EHes. Although the two stars have similar abundances for elements up through the iron-group, they differ strikingly in their abundances of heavier elements: V1920 Cyg is enriched by a factor of 30 in light neutron-capture elements (Y/Fe, Zr/Fe) relative to HD 124448. These differences in abundances of neutron-capture elements among EHes mirrors that exhibited by the RCrB stars, and is evidence supporting the view that there is an evolutionary connection between these two groups of hydrogen-deficient stars. Also, the abundances of Y and Zr in V1920 Cyg provide evidence that at least one EHe star went through a s-process synthesis episode in its earlier evolution. 20. Shadows and cavities in protoplanetary disks: HD163296, HD141569A, and HD150193A in polarized light CERN Document Server Garufi, Antonio; Schmid, Hans Martin; Avenhaus, Henning; Buenzli, Esther; Wolf, Sebastian 2014-01-01 The morphological evolution of dusty disks around young (few Myr-old) stars is pivotal to better understand planet formation. Since both dust grains and the global disk geometry evolve on short timescale, high-resolution imaging of a sample of objects may provide important hints towards such an evolution. We enlarge the sample of protoplanetary disks imaged in polarized light with high-resolution by observing the Herbig Ae/Be stars HD163296, HD141569A, and HD150193A. We integrate our data with previous datasets to paint a larger picture of their morphology. We report a weak detection of the disk around HD163296 in both H and Ks band. The disk is resolved as a broken ring structure with a significan surface brightness drop inward of 0.6 arcsec. No sign of extended polarized emission is detected from the disk around HD141569A and HD150193A. We propose that the absence of scattered light in the inner 0.6 arcsec around HD163296 and the non-detection of the disk around HD150193A may be due to similar geometric fac... 1. HD 18078: A very slowly rotating Ap star with an unusual magnetic field structure Science.gov (United States) Mathys, G.; Romanyuk, I. I.; Kudryavtsev, D. O.; Landstreet, J. D.; Pyper, D. M.; Adelman, S. J. 2016-02-01 Context. The existence of a significant population of Ap stars with very long rotation periods (up to several hundred years) has progressively emerged over the past two decades. However, only lower limits of the periods are known for most of them because their variations have not yet been observed over a sufficient timebase. Aims: We determine the rotation period of the slowly rotating Ap star HD 18078 and we derive constraints on the geometrical structure of its magnetic field. Methods: We combine measurements of the mean magnetic field modulus obtained from 1990 to 1997 with determinations of the mean longitudinal magnetic field spanning the 1999-2007 time interval to derive an unambiguous value of the rotation period. We show that this value is consistent with photometric variations recorded in the Strömgren uvby photometric system between 1995 and 2004. We fit the variations of the two above-mentioned field moments with a simple model to constrain the magnetic structure. Results: The rotation period of HD 18078 is (1358 ± 12) d. The geometrical structure of its magnetic field is consistent to first order with a colinear multipole model whose axis is offset from the centre of the star. Conclusions: HD 18078 is only the fifth Ap star with a rotation period longer than 1000 d for which the exact value of that period (as opposed to a lower limit) could be determined. The strong anharmonicity of the variations of its mean longitudinal magnetic field and the shift between their extrema and those of the mean magnetic field modulus are exceptional and indicative of a very unusual magnetic structure. Based in part on observations made at Observatoire de Haute Provence (CNRS), France; at Kitt Peak National Observatory, National Optical Astronomy Observatory (NOAO Prop. ID: KP2442; PI: T. Lanz), which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation; at the Canada 2. Surface structure of the CoRoT CP2 target star HD 50773 CERN Document Server Lüftinger, T; Weiss, W; Petit, P; Aurière, M; Nesvacil, N; Gruberbauer, M; Shulyak, D; Alecian, E; Baglin, A; Baudin, F; Catala, C; Donati, J -F; Kochukhov, O; Michel, E; Piskunov, N; Roudier, T; Samadi, R 2009-01-01 We compare surface maps of the chemically peculiar star HD 50773 produced with a Bayesian technique and based on high quality CoRoT photometry with those derived from rotation phase resolved spectropolarimetry. The goal is to investigate the correlation of surface brightness with surface chemical abundance distribution and the stellar magnetic field. The rotational period of the star was determined from a nearly 60 day long continuous light curve obtained during the initial run of CoRoT. Using a Bayesian approach to star-spot modelling, which in this work is applied for the first time for the photometric mapping of a CP star, we derived longitudes, latitudes and radii of four different spot areas. Additional parameters like stellar inclination and the spot's intensities were also determined. The CoRoT observations triggered an extensive ground-based spectroscopic and spectropolarimetric observing campaign and enabled us to obtain 19 different high resolution spectra in Stokes parameters I and V with NARVAL, E... 3. A search for solar-like oscillations in the Am star HD 209625 CERN Document Server Carrier, F; Leyder, J C; Debernardi, Y; Royer, F 2007-01-01 The goal is to test the structure of hot metallic stars, and in particular the structure of a near-surface convection zone using asteroseismic measurements. Indeed, stellar models including a detailed treatement of the radiative diffusion predict the existence of a near-surface convection zone in order to correctly reproduce the anomalies in surface abundances that are observed in Am stars. The Am star HD 209625 was observed with the Harps spectrograph mounted on the 3.6-m telescope at the ESO La Silla Observatory (Chile) during 9 nights in August 2005. This observing run allowed us to collect 1243 radial velocity (RV) measurements, with a standard deviation of 1.35 m/s. The power spectrum associated with these RV measurements does not present any excess. Therefore, either the structure of the external layers of this star does not allow excitation of solar-like oscillations, or the amplitudes of the oscillations remain below 20-30 cm/s (depending on their frequency range). 4. Sparse aperture masking at the VLT I. Faint companion detection limits for the two debris disk stars HD 92945 and HD 141569 CERN Document Server Lacour, S; Amico, P; Ireland, M; Ehrenreich, D; Huelamo, N; Lagrange, A -M 2011-01-01 Observational data on companion statistics around young stellar systems is needed to flesh out the formation pathways for extrasolar planets and brown dwarfs. Aperture masking is a new technique that is able to address an important part of this discovery space. We observed the two debris disk systems HD 92945 and HD 141569 with sparse aperture masking (SAM), a new mode offered on the NaCo instrument at the VLT. A search for faint companions was performed using a detection strategy based on the analysis of closure phases recovered from interferograms recorded on the Conica camera. Our results demonstrate that SAM is a very competitive mode in the field of companion detection. We obtained 5 sigma high-contrast detection limits at lambda/D of 2.5x10^{-3} (\\Delta L' = 6.5) for HD 92945 and 4.6x10^{-3} (\\Delta L' = 5.8) for HD 141569. According to brown dwarf evolutionary models, our data impose an upper mass boundary for any companion for the two stars to, respectively, 18 and 22 Jupiter masses at minimum separat... 5. HD5980 OpenAIRE Koenigsberger, C 2015-01-01 HD5980 is a multiple system containing at least 3 very massive and luminous stars. Located in the Small Magellanic Cloud, it is an ideal system for studying the massive star structure and evolutionary processes in low-metallicity environments. Intensely observed over the past few decades, HD5980 is a treasure trove of information on stellar wind structure, on wind-wind collisions and on the formation of wind-blown circumstellar structures. In addition, its characteristics suggest that the ecl... 6. Transit confirmation and improved stellar and planet parameters for the super-Earth HD 97658 b and its host star Energy Technology Data Exchange (ETDEWEB) Van Grootel, V.; Gillon, M.; Scuflaire, R. [Institut d' Astrophysique et de Géophysique, Université de Liège, 17 Allée du 6 Août, B-4000 Liège (Belgium); Valencia, D. [Department of Physical and Environmental Sciences, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4 (Canada); Madhusudhan, N.; Demory, B.-O.; Queloz, D. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Dragomir, D. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr. Suite 102, Goleta, CA 93117 (United States); Howe, A. R.; Burrows, A. S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Deming, D. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Ehrenreich, D.; Lovis, C.; Mayor, M.; Pepe, F.; Segransan, D.; Udry, S. [Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, CH-1290 Sauverny (Switzerland); Seager, S., E-mail: valerie.vangrootel@ulg.ac.be [Department of Earth, Atmospheric and Planetary Sciences, Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States) 2014-05-01 Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass (M {sub *} = 0.77 ± 0.05 M {sub ☉}) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-High Resolution Echelle Spectrometer (Keck-HIRES) radial velocities and Microvariability and Oscillations of STars (MOST) and Spitzer photometry. HD 97658 b is a massive (M{sub P}=7.55{sub −0.79}{sup +0.83} M{sub ⊕}) and large (R{sub P}=2.247{sub −0.095}{sup +0.098}R{sub ⊕} at 4.5 μm) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, of at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the knowledge of the HD 97658 system, in particular by constraining its age. Orbiting a bright host star, HD 97658 b will be a key target for upcoming space missions such as the Transiting Exoplanet Survey Satellite (TESS), the Characterizing Exoplanet Satellite (CHEOPS), the Planetary Transits and Oscillations of stars (PLATO), and the James Webb Space Telescope to characterize thoroughly its structure and atmosphere. 7. Gas in the protoplanetary disc of HD 169142 : Herschel's view NARCIS (Netherlands) Meeus, G.; Pinte, C.; Woitke, P.; Montesinos, B.; Mendigutia, I.; Riviere-Marichalar, P.; Eiroa, C.; Mathews, G. S.; Vandenbussche, B.; Howard, C. D.; Roberge, A.; Sandell, G.; Duchene, G.; Menard, F.; Grady, C. A.; Dent, W. R. F.; Kamp, I.; Augereau, J. C.; Thi, W. F.; Tilling, I.; Alacid, J. M.; Andrews, S.; Ardila, D. R.; Aresu, G.; Barrado, D.; Brittain, S.; Ciardi, D. R.; Danchi, W.; Fedele, D.; de Gregorio-Monsalvo, I.; Heras, A.; Huelamo, N.; Krivov, A.; Lebreton, J.; Liseau, R.; Martin-Zaidi, C.; Mora, A.; Morales-Calderon, M.; Nomura, H.; Pantin, E.; Pascucci, I.; Phillips, N.; Podio, L.; Poelman, D. R.; Ramsay, S.; Riaz, B.; Rice, K.; Solano, E.; White, G. J.; Williams, J. P.; Wright, G.; Walker, H. 2010-01-01 In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the open time key program GASPS, which is aimed a 8. HD 24355 observed by the Kepler K2 mission: A rapidly oscillating Ap star pulsating in a distorted quadrupole mode CERN Document Server Holdsworth, Daniel L; Smalley, Barry; Saio, Hideyuki; Handler, Gerald; Murphy, Simon J; Lehmann, Holger 2016-01-01 We present an analysis of the first Kepler K2 mission observations of a rapidly oscillating Ap (roAp) star, HD 24355 ($V=9.65$). The star was discovered in SuperWASP broadband photometry with a frequency of 224.31 d$^{-1}$, (2596.18$\\mu$Hz;$P = 6.4$min) and an amplitude of 1.51 mmag, with later spectroscopic analysis of low-resolution spectra showing HD 24355 to be an A5 Vp SrEu star. The high precision K2 data allow us to identify 13 rotationally split sidelobes to the main pulsation frequency of HD 24355. This number of sidelobes combined with an unusual rotational phase variation show this star to be the most distorted quadrupole roAp pulsator yet observed. In modelling this star, we are able to reproduce well the amplitude modulation of the pulsation, and find a close match to the unusual phase variations. We show this star to have a pulsation frequency higher than the critical cut-off frequency. This is currently the only roAp star observed with the Kepler spacecraft in Short Cadence mode that has a p... 9. Chandra Characterization of X-ray Emission in the Young F-Star Binary System HD 113766 CERN Document Server Lisse, C M; Wolk, S J; Günther, H M; Chen, C H; Grady, C A 2016-01-01 Using Chandra we have obtained imaging X-ray spectroscopy of the 10 to 16 Myr old F-star binary HD 113766. We individually resolve the binary components for the first time in the X-ray and find a total 0.3 to 2.0 keV luminosity of 2.2e29 erg/sec, consistent with previous RASS estimates. We find emission from the easternmost, infrared-bright, dusty member HD 113766A to be only 10% that of the western, infrared-faint member HD 113766B. There is no evidence for a 3rd late-type stellar or sub-stellar member of HD113766 with Lx > 6e25 erg s-1 within 2 arcmin of the binary pair. The ratio of the two stars Xray luminosity is consistent with their assignments as F2V and F6V by Pecaut et al. (2012). The emission is soft for both stars, kTApec = 0.30 to 0.50 keV, suggesting X-rays produced by stellar rotation and/or convection in young dynamos, but not accretion or outflow shocks which we rule out. A possible 2.8 +/- 0.15 (2{\\sigma}) hr modulation in the HD 113766B X-ray emission is seen, but at very low confidence and... 10. Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star Science.gov (United States) Mugrauer, M.; Dinçel, B. 2016-07-01 We report on our follow-up spectroscopy of HD 1071478 B, a recently detected faint co-moving companion of the exoplanet host star HD 107148 A. The companion is separated from its primary star by about 35 arcsec (or 1790 AU of projected separation) and its optical and near infrared photometry is consistent with a white dwarf, located at the distance of HD 107148 A. In order to confirm the white dwarf nature of the co-moving companion, we obtained follow-up spectroscopic observations of HD 107148 B with CAFOS at the CAHA 2.2 m telescope. According to our CAFOS spectroscopy HD 107148 B is a DA white dwarf with an effective temperature in the range between 5900 and 6400 K. The properties of HD 107148 B can further be constrained with the derived effective temperature and the known visual and infrared photometry of the companion, using evolutionary models of DA white dwarfs. We obtain for HD 107148 B a mass of 0.56±0.05 M_ȯ, a luminosity of (2.0±0.2)×10-4 L_ȯ, log g [cm s-2])=7.95±0.09, and a cooling age of 2100±270 Myr. With its white dwarf companion the exoplanet host star HD 107148 A forms an evolved stellar system, which hosts at least one exoplanet. So far, only few of these evolved systems are known, which represent only about 5 % of all known exoplanet host multiple stellar systems. HD 107148 B is the second confirmed white dwarf companion of an exoplanet host star with a projected separation to its primary star of more than 1000 AU. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). 11. Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star Science.gov (United States) Mugrauer, M.; Dinçel, B. 2016-07-01 We report on our follow-up spectroscopy of HD 1071478 B, a recently detected faint co-moving companion of the exoplanet host star HD 107148 A. The companion is separated from its primary star by about 35 arcsec (or 1790 AU of projected separation) and its optical and near infrared photometry is consistent with a white dwarf, located at the distance of HD 107148 A. In order to confirm the white dwarf nature of the co-moving companion, we obtained follow-up spectroscopic observations of HD 107148 B with CAFOS at the CAHA 2.2 m telescope. According to our CAFOS spectroscopy HD 107148 B is a DA white dwarf with an effective temperature in the range between 5900 and 6400 K. The properties of HD 107148 B can further be constrained with the derived effective temperature and the known visual and infrared photometry of the companion, using evolutionary models of DA white dwarfs. We obtain for HD 107148 B a mass of 0.56±0.05 M_⊙, a luminosity of (2.0±0.2)×10-4 L_⊙, log g [cm s-2])=7.95±0.09, and a cooling age of 2100±270 Myr. With its white dwarf companion the exoplanet host star HD 107148 A forms an evolved stellar system, which hosts at least one exoplanet. So far, only few of these evolved systems are known, which represent only about 5 % of all known exoplanet host multiple stellar systems. HD 107148 B is the second confirmed white dwarf companion of an exoplanet host star with a projected separation to its primary star of more than 1000 AU. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). 12. A dynamical magnetosphere model for periodic Halpha emission from the slowly rotating magnetic O star HD191612 CERN Document Server Sundqvist, Jon O; Owocki, Stanley P; Townsend, Richard H D; Howarth, Ian D; Wade, Gregg A 2012-01-01 The magnetic O-star HD191612 exhibits strongly variable, cyclic Balmer line emission on a 538-day period. We show here that its variable Halpha emission can be well reproduced by the rotational phase variation of synthetic spectra computed directly from full radiation magneto-hydrodynamical simulations of a magnetically confined wind. In slow rotators such as HD191612, wind material on closed magnetic field loops falls back to the star, but the transient suspension of material within the loops leads to a statistically overdense, low velocity region around the magnetic equator, causing the spectral variations. We contrast such "dynamical magnetospheres" (DMs) with the more steady-state "centrifugal magnetospheres" of stars with rapid rotation, and discuss the prospects of using this DM paradigm to explain periodic line emission from also other non-rapidly rotating magnetic massive stars. 13. Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740 CERN Document Server Krticka, J; Markova, H; Mikulasek, Z; Zverko, J; Prvak, M; Skarka, M 2013-01-01 The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2m MPG/ESO telescope. We are able to reproduce the observed visual ligh... 14. KNOW THE STAR, KNOW THE PLANET. V. CHARACTERIZATION OF THE STELLAR COMPANION TO THE EXOPLANET HOST STAR HD 177830 Energy Technology Data Exchange (ETDEWEB) Roberts, Lewis C. Jr.; Beichman, Charles; Burruss, Rick; Cady, Eric; Lockhart, Thomas G. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena CA 91109 (United States); Oppenheimer, Rebecca; Brenner, Douglas; Luszcz-Cook, Statia; Nilsson, Ricky [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Crepp, Justin R. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Baranec, Christoph [Institute for Astronomy, University of Hawai‘i at Mānoa, Hilo, HI 96720-2700 (United States); Dekany, Richard; Hillenbrand, Lynne [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Hinkley, Sasha [School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL (United Kingdom); King, David; Parry, Ian R. [Institute of Astronomy, University of Cambridge, Madingley Road., Cambridge, CB3 OHA (United Kingdom); Pueyo, Laurent [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Sivaramakrishnan, Anand; Soummer, Rémi [Department of Astronomy, Stockholm University, AlbaNova University Center, Roslagstullsbacken 21, SE-10691 Stockholm (Sweden); Rice, Emily L., E-mail: lewis.c.roberts@jpl.nasa.gov [Department of Engineering Science and Physics, College of Staten Island, City University of New York, Staten Island, NY 10314 (United States); and others 2015-10-15 HD 177830 is an evolved K0IV star with two known exoplanets. In addition to the planetary companions it has a late-type stellar companion discovered with adaptive optics imagery. We observed the binary star system with the PHARO near-IR camera and the Project 1640 coronagraph. Using the Project 1640 coronagraph and integral field spectrograph we extracted a spectrum of the stellar companion. This allowed us to determine that the spectral type of the stellar companion is a M4 ± 1 V. We used both instruments to measure the astrometry of the binary system. Combining these data with published data, we determined that the binary star has a likely period of approximately 800 years with a semimajor axis of 100–200 AU. This implies that the stellar companion has had little or no impact on the dynamics of the exoplanets. The astrometry of the system should continue to be monitored, but due to the slow nature of the system, observations can be made once every 5–10 years. 15. HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang CERN Document Server Bond, Howard E; VandenBerg, Don A; Schaefer, Gail H; Harmer, Dianne; 10.1088/2041-8205/765/1/L12 2013-01-01 HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the HR diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 +/- 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 +/- 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especia... 16. A resolved, au-scale gas disk around the B[e] star HD 50138 CERN Document Server Ellerbroek, L E; Kraus, S; Perraut, K; Kluska, J; Bouquin, J B le; Fernandes, M Borges; de Souza, A Domiciano; Maaskant, K M; Kaper, L; Tramper, F; Mourard, D; Tallon-Bosc, I; Brummelaar, T ten; Sitko, M L; Lynch, D K; Russell, R W 2014-01-01 HD 50138 is a B[e] star surrounded by a large amount of circumstellar gas and dust. Its spectrum shows characteristics which may indicate either a pre- or a post-main-sequence system. Mapping the kinematics of the gas in the inner few au of the system contributes to a better understanding of its physical nature. We present the first high spatial and spectral resolution interferometric observations of the Br-gamma line of HD~50138, obtained with VLTI/AMBER. The line emission originates from a region more compact (up to 3 au) than the continuum-emitting region. Blue- and red-shifted emission originates from the two different hemispheres of an elongated structure perpendicular to the polarization angle. The velocity of the emitting medium decreases radially. An overall offset along the NW direction between the line- and continuum-emitting regions is observed. We compare the data with a geometric model of a thin Keplerian disk and a spherical halo on top of a Gaussian continuum. Most of the data are well reproduc... 17. The composite nature of the peculiar star HR 6560 (HD 159870) Science.gov (United States) Wegner, Gary; Cowley, Charles R. 1992-01-01 Ground-based high-dispersion photographic spectra and ultraviolet spectra obtained with the IUE satellite are described and employed to determine the nature of the peculiar star HR 6560 (HD 159870). Previously this object had been described as both a composite system and as a strong Fm star. The UBVRI, Stromgren, and ultraviolet colors of HR 6560 are compared with objects classified composite from the Bright Star Catalogue and normal dwarfs and giants. The colors of HR 6560 are not unusual for a composite and are consistent with a late-A dwarf, combined with a late-G or early-K giant. The ultraviolet satellite clearly shows the presence of an A component, but its precise spectral type is difficult to assign. The IUE and TD-1 data suggest that the ultraviolet is dominated by light from an A5 V secondary and the visual from a GO III primary. This does not agree well with the most plausible model that fits the visual photometry. The peculiar nature of HR 6560's spectrum is most likely due to its composite nature. 18. Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237 Science.gov (United States) Alvarado-Gómez, J. D.; Hussain, G. A. J.; Grunhut, J.; Fares, R.; Donati, J.-F.; Alecian, E.; Kochukhov, O.; Oksala, M.; Morin, J.; Redfield, S.; Cohen, O.; Drake, J. J.; Jardine, M.; Matt, S.; Petit, P.; Walter, F. M. 2015-10-01 We analyse the magnetic activity characteristics of the planet-hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field measurements that is consistent with our ZDI analysis with a period of 7 days. We investigate the effect of customising the LSD mask to the line depths of the observed spectrum and find that it has a minimal effect on the shape of the extracted Stokes V profile but does result in a small increase in the S/N (~7%). We find that using a Milne-Eddington solution to describe the local line profile provides a better fit to the LSD profiles in this slowly rotating star, which also affects the recovered ZDI field distribution. We also introduce a fit-stopping criterion based on the information content (entropy) of the ZDI map solution set. The recovered magnetic field maps show a strong (+90 G) ring-like azimuthal field distribution and a complex radial field dominating at mid latitudes (~45 degrees). Similar magnetic field maps are recovered from data acquired five months apart. Future work will investigate how this surface magnetic field distribution affeccts the coronal magnetic field and extended environment around this planet-hosting star. 19. HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star? CERN Document Server Sahin, Timur; Klochkova, Valentina G; Panchuk, Vladimir E 2016-01-01 We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0$\\pm$0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich stars yet analyzed. The abundance analysis of this luminous star is based on high resolution and high quality (S/N$\\approx$120--420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over twenty-one epochs. Standard 1D {\\sc LTE} analysis provides a fresh determination of the atmospheric parameters over all epochs: \\Teff = 7350$\\pm$200 \\kelvin, \\logg = +0.6$\\pm$0.3, and a microturbulent velocity$\\xi =$6.6$\\pm$1.6 km s$^{\\rm -1}$and [Fe/H] = 0.4$\\pm$0.2, and a carbon abundance [C/Fe]=$-$0.19$\\pm$0.30. We find oxygen abundance [O/Fe]=$-$0.25$\\pm$0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0$\\pm$2.0 km s$^{\\rm -1}$is determined from both strong and we... 20. An Icy Kuiper Belt Around the Young Solar-type Star HD 181327 Science.gov (United States) Lebreton, J.; Augereau, J.-C.; Thi, W.-F.; Roberge, A.; Donaldson, J; Schneider, G.; Maddison, S. T.; Menard, F.; Riviere-Marichalar, P.; Matthews, G. S.; Kamp, I.; Pinte, C.; Dent, W. R. F.; Barrado, D.; Duchene, G.; Gonzalez, J.-F.; Grady C. A.; Meeus,G.; Pantin, E.; Williams, J. P.; Woitke, P. 2012-01-01 Context. HD 181327 is a young main sequence F5/F6 V star belonging to the Beta Pictoris moving group (age approx.. 12 Myr). It harbors an optically thin belt of circumstellar material at radius approx.. 90 AU, presumed to result from collisions in a population of unseen planetesimals. Aims. We aim to study the dust properties in the belt in details, and to constrain the gas-to-dust ratio. Methods. We obtained far-infrared photometric observations of HD 181327 with the PACS instrument onboard the Herschel Space Observatory, complemented by new 3.2 mm observations carried with the ATCA array. The geometry of the belt is constrained with newly reduced HST/NICMOS scattered light images that allow the degeneracy between the disk geometry and the dust properties to be broken. We then use the radiative transfer code GRaTeR to compute a large grid of models, and we identify the grain models that best reproduce the spectral energy distribution (SED) through a Bayesian analysis. We attempt to detect the oxygen and ionized carbon fine-structure lines with Herschel/PACS spectroscopy, providing observables to our photochemical code ProDiMo. Results. The HST observations confirm that the dust is confined in a narrow belt. The continuum is detected with Herschel/PACS completing nicely the SED in the far-infrared. The disk is marginally resolved with both PACS and ATCA. A medium integration of the gas spectral lines only provides upper limits on the [OI] and [CII] line fluxes.We show that the HD 181327 dust disk consists of micron-sized grains of porous amorphous silicates and carbonaceous material surrounded by an important layer of ice, for a total dust mass of approx.. 0.05 Solar Mass (in grains up to 1 mm). We discuss evidences that the grains consists of fluffy aggregates. The upper limits on the gas atomic lines do not provide unambiguous constraints: only if the PAH abundance is high, the gas mass must be lower than approx. 17 Solar Mass. Conclusions. Despite the weak 1. An Icy Kuiper-Belt Around the Young Solar-Type Star HD 181327 Science.gov (United States) Lebreton, J.; Augereau, J.-C.; Thi, W.-F.; Roberge, A.; Donaldson, J.; Schneider, G.; Maddison, S. T.; Menard, F.; Riviere-Marichalar, P.; Mathews, G. S.; Kamp, I.; Pinte, C.; Dent, W. R. F.; Barrado, D.; Duchene, G.; Gonzalez, J.-F.; Grady, C. A.; Meeus, G.; Pantin, E.; Williams, J. P.; Woitke, P. 2011-01-01 HD 181327 is a young Main Sequence F5/F6 V star belonging to the Beta Pictoris moving group (age approx 12 Myr). It harbors an optically thin belt of circumstellar material at approx90 AU, presumed to result from collisions in a populat.ion of unseen planetesimals. Aims. We aim to study the dust properties in the belt in great details, and to constrain the gas-to-dust ratio. Methods. We obtained far-IR photometric observations of HD 181327 with the PACS instrument onboard the Herschel Space Observatory, complemented by new 3.2 nun observations carried with the ATCA array. The geometry of the belt is constrained with newly reduced HST /NICMOS scattered light images that break the degeneracy between the disk geometry and the dust properties. We then use the radiative transfer code GRaTer to compute a large grid of dust models, and we apply a Bayesian inference method to identify the grain models that best reproduce the SED. We attempt to detect the oxygen and ionized carbon fine-structure lines with Herschel/PACS spectroscopy, providing observables to our photochemical code ProDiMo. Results. The HST observations confirm that the dust is confined in a narrow belt. The continuum is detected with Herschel/PACS completing nicely the SED in the far-infrared. The disk is marginally resolved with both PACS and ATCA. A medium integration of the gas spectral lines only provides upper limits on the [OI] and [CII] line fluxes. We show that the HD 181327 dust disk consists of micron-sized grains of porous amorphous silicates and carbonaceous material surrounded by an import.ant layer of ice for a total dust mass of approx 0.05 stellar Mass. We discuss evidences that the grains consists of fluffy aggregates. The upper limits on the gas atomic lines do not provide unambiguous constraints: only if the PAH abundance is high, the gas mass must be lower than approx 17 Stellar Mass Conclusions. Despite the weak constraints on the gas disk, the age of HD 181327 and the properties of the 2. INTEGRAL Observations of the Enigmatic Be Stars (gamma) Cassiopeiae and HD 110432 Science.gov (United States) Sturner, S. J.; Shrader, C. R. 2007-01-01 We present the results of a hard X-ray study of the Be stars gamma Cassiopeiae and HD 110432 based on observations made with the INTEGRAL observatory. These stars are known to be moderately strong, X-ray sources (L(sub x) approx. equal to = 10(sup 32)-10(sup 33) erg per second). These values are at the extreme high end of the known luminosity distribution for active coronal systems, but several orders of magnitude below typical X-ray binaries. The hard X-ray spectra for these systems are quite similar. They can be well fitted by either optically thin thermal plasma models with kT = 12.5 - 14 keV or a cutoff powerlaw + gaussian line model with photon indices in the 1.3 - 1.5 range and a line energy of 6.7 keV. The 20-50 keV light curves show no evidence for flaring and no significant evidence for periodic variability. It has been proposed that the X-ray emission is due to either accretion onto a white dwarf companion or magnetic activity near the surface of the Be star. We discuss in detail the pros and cons of each scenario towards explaining our spectral and temporal results. Given that both thermal and nonthermal models fit the data equally well, we cannot use the spectra to delineate between these two scenarios. Recent observations indicate that gamma Cas has a approx. 1 solar mass companion in a 203.59 day orbit. This is consistent with the white dwarf - Be star binary model but the lack of periodic modulation of the flux on this timescale calls this conclusion into question. On the other hand the lack of flaring activity may rule against the magnetic activity model. We discuss advances in observations and theory that need to be made to resolve the origin of these systems. 3. Non-radial pulsations in the γ Doradus star HD 195068 Science.gov (United States) Jankov, S.; Mathias, P.; Chapellier, E.; Le Contel, J.-M.; Sareyan, J.-P. 2006-07-01 We present high resolution spectroscopic observations of the γ Doradus star HD 195068. About 230 spectra were collected over 2 years. Time series analysis performed on radial velocity data shows a main peak at 1.61 d-1 , a frequency not yet detected in photometry. The Hipparcos photometric 1.25 d-1 frequency is easily recovered as is 1.30 d-1 while the third photometric frequency, 0.97 d-1 , is only marginally present. The good quality of our data, which includes 196 spectra collected over seven consecutive nights, shows that both the 1.61 d-1 and intermediate 1.27 d-1 (mixture of 1.25 and 1.30 d-1 ) frequencies are present in the line profile variations. Using the Fourier-Doppler Imaging (FDI) method, the variability associated with 1.61 d-1 can be successfully modeled by a non-radial pulsation mode ℓ=5± 1, |m|=4± 1. For the intermediate frequency 1.27 d-1 we deduce ℓ=4± 1, |m|=3± 1. Evidence that the star is not pulsating in the radial mode (ℓ=0) rules out a previous classification as an RR Lyrae type star. We investigate the time variability of FDI power spectra concluding that the observed temporal variability of modes can be explained by a beating phenomenon between closely spaced frequencies of two non-radial modes. The distribution of the oscillation power within the line profile indicates that there is a significant tangential velocity component of oscillations characteristic of high radial order gravity modes which are predicted to be observed in γ Doradus type stars. 4. Benchmark stars for Gaia Fundamental properties of the Population II star HD 140283 from interferometric, spectroscopic, and photometric data Science.gov (United States) Creevey, O. L.; Thévenin, F.; Berio, P.; Heiter, U.; von Braun, K.; Mourard, D.; Bigot, L.; Boyajian, T. S.; Kervella, P.; Morel, P.; Pichon, B.; Chiavassa, A.; Nardetto, N.; Perraut, K.; Meilland, A.; Mc Alister, H. A.; ten Brummelaar, T. A.; Farrington, C.; Sturmann, J.; Sturmann, L.; Turner, N. 2015-03-01 Metal-poor halo stars are important astrophysical laboratories that allow us to unravel details about many aspects of astrophysics, including the chemical conditions at the formation of our Galaxy, understanding the processes of diffusion in stellar interiors, and determining precise effective temperatures and calibration of colour-effective temperature relations. To address any of these issues the fundamental properties of the stars must first be determined. HD 140283 is the closest and brightest metal-poor Population II halo star (distance = 58 pc and V = 7.21), an ideal target that allows us to approach these questions, and one of a list of 34 benchmark stars defined for Gaia astrophysical parameter calibration. In the framework of characterizing these benchmark stars, we determined the fundamental properties of HD 140283 (radius, mass, age, and effective temperature) by obtaining new interferometric and spectroscopic measurements and combining them with photometry from the literature. The interferometric measurements were obtained using the visible interferometer VEGA on the CHARA array and we determined a 1D limb-darkened angular diameter of θ1D = 0.353 ± 0.013 milliarcsec. Using photometry from the literature we derived the bolometric flux in two ways: a zero reddening solution (AV = 0.0 mag) of Fbol of 3.890 ± 0.066 × 10-8 erg s-1 cm-2, and a maximum of AV = 0.1 mag solution of 4.220 ± 0.067 × 10-8 erg s-1 cm-2. The interferometric Teff is thus between 5534 ± 103 K and 5647 ± 105 K and its radius is R = 2.21 ± 0.08R⊙. Spectroscopic measurements of HD 140283 were obtained using HARPS, NARVAL, and UVES and a 1D LTE analysis of Hα line wings yielded Teffspec = 5626 ± 75 K. Using fine-tuned stellar models including diffusion of elements we then determined the mass M and age t of HD 140283. Once the metallicity has been fixed, the age of the star depends on M, initial helium abundance Yi, andmixing-length parameter α, only two of which are 5. Chemical stratification in the atmosphere of Ap star HD 133792. Regularized solution of the vertical inversion problem CERN Document Server Kochukhov, O; Ryabchikova, T A; Makaganyk, V; Bagnulo, S 2006-01-01 High spectral resolution studies of cool Ap stars reveal conspicuous anomalies of the shape and strength of many absorption lines. This is a signature of large atmospheric chemical gradients produced by the selective radiative levitation and gravitational settling of chemical species. Here we present a new approach to mapping the vertical chemical structures in stellar atmospheres. We have developed a regularized chemical inversion procedure that uses all information available in high-resolution stellar spectra. The new technique for the first time allowed us to recover chemical profiles without making a priori assumptions about the shape of chemical distributions. We have derived average abundances and applied the vertical inversion procedure to the high-resolution VLT UVES spectra of the weakly magnetic, cool Ap star HD 133792. Our analysis yielded improved estimates of the atmospheric parameters of HD 133792. We show that this star has negligible vsini and the mean magnetic field modulus =1.1+/-0.1 kG. We ... 6. The unstable fate of the planet orbiting the A-star in the HD 131399 triple stellar system CERN Document Server Veras, Dimitri; Gaensicke, Boris T 2016-01-01 Validated planet candidates need not lie on long-term stable orbits, and instability triggered by post-main-sequence stellar evolution can generate architectures which transport rocky material to white dwarfs, polluting them. The giant planet HD 131399Ab orbits its parent A star at a projected separation of about 50-100 au. The host star, HD 131399A, is part of a hierarchical triple with HD 131399BC being a close binary separated by a few hundred au from the A star. Here, we determine the fate of this system, and find that (i) stability along the main sequence is achieved only for a favourable choice of parameters within the errors, and (ii) even for this choice, in almost every instance the planet is ejected during the transition between the giant branch and white dwarf phases of HD 131399A. This result provides an example of both how the free-floating planet population may be enhanced by similar systems, and how instability can manifest in the polluted white dwarf progenitor population. 7. Kepler-21b: A 1.6REarth Planet Transiting the Bright Oscillating F Subgiant Star HD 179070 CERN Document Server Howell, Steve B; Bryson, Stephen T; Quinn, Samuel N; Marcy, Geoffrey W; Isaacson, Howard; Ciardi, David R; Chaplin, William J; Metcalfe, Travis S; Monteiro, Mario J P F G; Appourchaux, Thierry; Basu, Sarbani; Creevey, Orlagh L; Gilliland, Ronald L; Quirion, Pierre-Olivier; Stello, Denis; Kjeldsen, Hans; Christensen-Dalsgaard, Jorgen; Elsworth, Yvonne; García, Rafael A; Houdek, Gunter; Karoff, Christoffer; Molenda-Żakowicz, Joanna; Thompson, Michael J; Verner, Graham A; Torres, Guillermo; Fressin, Francois; Crepp, Justin R; Adams, Elisabeth; Dupree, Andrea; Sasselov, Dimitar D; Dressing, Courtney D; Borucki, William J; Koch, David G; Lissauer, Jack J; Latham, David W; Gautier, Thomas N; Everett, Mark; Horch, Elliott; Batalha, Natalie M; Dunham, Edward W; Szkody, Paula; Silva, David R; Mighel, Ken; Holberg, Jay; Ballot, Jer^ome; Bedding, Timothy R; Bruntt, Hans; Campante, Tiago L; Handberg, Rasmus; Hekker, Saskia; Huber, Daniel; Mathur, Savita; Mosser, Benoit; Régulo, Clara; White, Timothy R; Christiansen, Jessie L; Middour, Christopher K; Haas, Michael R; Hall, Jennifer R; Jenkins, Jon M; McCaulif, Sean; Fanelli, Michael N; Kulesa, Craig; McCarthy, Don; Henze, Christopher E 2011-01-01 We present Kepler observations of the bright (V=8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R_Earth object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequencypower spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34{\\pm}0.06 M{\\circ} and 1.86{\\pm}0.04 R{\\circ} respectively, as well as yielding an age of 2.84{\\pm}0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3{\\sigma}) that the transit event is caused by a 1.64{\\pm}0.04 R_Earth exoplanet in a 2.785755{\\pm}0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit ... 8. HD 50844: the new look of Delta Sct stars from CoRoT space photometry CERN Document Server Poretti, E; Garrido, R; Lefèvre, L; Mantegazza, L; Rainer, M; Rodríguez, E; Uytterhoeven, K; Amado, P J; Martin-Ruiz, S; Moya, A; Niemczura, E; Suárez, J C; Zima, W; Baglin, A; Auvergne, M; Baudin, F; Catala, C; Samadi, R; Alvarez, M; Mathias, P; Paparo, M; Papics, P; Plachy, E 2009-01-01 It has also been suggested that the detection of a wealth of very low amplitude modes in Delta Sct stars was only a matter of signal--to--noise ratio. Access to this treasure, impossible from the ground, is one of the scientific aims of the space mission CoRoT, a space mission developed and operated by CNES. This work presents the results obtained on HD 50844: the 140,016 datapoints were analysed using independent approaches and several checks performed. A level of 10^{-5} mag was reached in the amplitude spectra of the CoRoT timeseries. The frequency analysis of the CoRoT timeseries revealed hundreds of terms in the frequency range 0--30 d^{-1}. All the cross--checks confirmed this new result. The initial guess that Delta Sct stars have a very rich frequency content is confirmed. The spectroscopic mode identification gives theoretical support since very high--degree modes (up to ell=14) are identified. We also prove that cancellation effects are not sufficient in removing the flux variations associated to th... 9. Activity and Magnetic Field Structure of the Sun-Like Planet Hosting Star HD 1237 CERN Document Server Alvarado-Gómez, J D; Grunhut, J; Fares, R; Donati, J -F; Alecian, E; Kochukhov, O; Oksala, M; Morin, J; Redfield, S; Cohen, O; Drake, J J; Jardine, M; Matt, S; Petit, P; Walter, F M 2015-01-01 We analyse the magnetic activity characteristics of the planet hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field measurements consistent with our ZDI analysis, with a period of 7 days. We investigate the effect of customising the LSD mask to the line depths of the observed spectrum and find that it has a minimal effect on shape of the extracted Stokes V profile but does result in a small increase in the S/N ($\\sim$7%). We find that using a Milne-Eddington solution to describe the local line profile provides a better fit to the LSD profiles in this slowly rotating star, which also impacts the recovered ZDI field distribution. We also introduce a fit-stopping criterion based on the information content (entropy) of the ZDI maps solution set. The recovered magnetic field maps show a strong (+90 G) ring-like azimuthal field distribution and a complex radial field dominating at mid latitudes ($\\sim$45 degr... 10. The circumstellar envelope of the C-rich post-AGB star HD 56126 CERN Document Server Hony, S; Waters, L B F M; De Koter, A 2003-01-01 We present a detailed study of the circumstellar envelope of the post-asymptotic giant branch 21 micron object'' HD 56126. We build a detailed dust radiative transfer model of the circumstellar envelope in order to derive the dust composition and mass, and the mass-loss history of the star. To model the emission of the dust we use amorphous carbon, hydrogenated amorphous carbon, magnesium sulfide and titanium carbide. We present a detailed parametrisation of the optical properties of hydrogenated amorphous carbon as a function of H/C content. The mid-infrared imaging and spectroscopy is best reproduced by a single dust shell from 1.2 to 2.6 arcsec radius around the central star. This shell originates from a short period during which the mass-loss rate exceeded 10^(-4) M_sun/yr. We find that the strength of the 21'' micron feature poses a problem for the TiC identification. The low abundance of Ti requires very high absorption cross-sections in the ultraviolet and visible wavelength range to explain the st... 11. THE LICK-CARNEGIE SURVEY: A NEW TWO-PLANET SYSTEM AROUND THE STAR HD 207832 Energy Technology Data Exchange (ETDEWEB) Haghighipour, Nader [Institute for Astronomy and NASA Astrobiology Institute, University of Hawaii-Manoa, Honolulu, HI 96822 (United States); Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institute of Washington, Washington, DC 20015 (United States); Rivera, Eugenio J.; Vogt, Steven S. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, Nashville, TN 37209 (United States) 2012-09-01 Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of Msin i = 0.56 M{sub Jup} and 0.73 M{sub Jup}, with orbital periods of {approx}162 and {approx}1156 days, and eccentricities of 0.13 and 0.27, respectively. Stroemgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have migrated from the region of giant planet formation to closer orbits. In order to examine the possibility of the existence of additional (small) planets in the system, we studied the orbital stability of hypothetical terrestrial-sized objects in the region between the two planets and interior to the orbit of the inner body. Results indicated that stable orbits exist only in a small region interior to planet b. However, the current observational data offer no evidence for the existence of additional objects in this system. 12. THE LICK-CARNEGIE SURVEY: A NEW TWO-PLANET SYSTEM AROUND THE STAR HD 207832 International Nuclear Information System (INIS) Keck/HIRES precision radial velocities of HD 207832 indicate the presence of two Jovian-type planetary companions in Keplerian orbits around this G star. The planets have minimum masses of Msin i = 0.56 MJup and 0.73 MJup, with orbital periods of ∼162 and ∼1156 days, and eccentricities of 0.13 and 0.27, respectively. Strömgren b and y photometry reveals a clear stellar rotation signature of the host star with a period of 17.8 days, well separated from the period of the radial velocity variations, reinforcing their Keplerian origin. The values of the semimajor axes of the planets suggest that these objects have migrated from the region of giant planet formation to closer orbits. In order to examine the possibility of the existence of additional (small) planets in the system, we studied the orbital stability of hypothetical terrestrial-sized objects in the region between the two planets and interior to the orbit of the inner body. Results indicated that stable orbits exist only in a small region interior to planet b. However, the current observational data offer no evidence for the existence of additional objects in this system. 13. Multi-level 3D non-LTE computations of lithium lines in the metal-poor halo stars HD140283 and HD84937 CERN Document Server Asplund, M; Botnen, A 2003-01-01 The lithium abundances in metal-poor halo stars are of importance for cosmology, galaxy evolution and stellar structure. In an attempt to study possible systematic errors in the derived Li abundances, the line formation of LiI lines has been investigated by means of realistic 3D hydrodynamical model atmospheres of halo stars and 3D non-LTE radiative transfer calculations. These are the first detailed 3D non-LTE computations reported employing a multi-level atomic model showing that such problems are now computationally tractable. The detailed computations reveal that the LiI population has a strong influence from the radiation field rather than the local gas temperature, indicating that the low derived Li abundances found by Asplund et al. (1999) are an artifact of their assumption of LTE. Relative to 3D LTE, the detailed calculations show pronounced over-ionization. In terms of abundances the 3D non-LTE values are within 0.05 dex of the 1D non-LTE results for the particular cases of HD140283 and HD84937, whi... 14. HD 147506b: A Supermassive Planet in an Eccentric Orbit Transiting a Bright Star Science.gov (United States) Bakos, G. Á.; Kovács, G.; Torres, G.; Fischer, D. A.; Latham, D. W.; Noyes, R. W.; Sasselov, D. D.; Mazeh, T.; Shporer, A.; Butler, R. P.; Stefanik, R. P.; Fernández, J. M.; Sozzetti, A.; Pál, A.; Johnson, J.; Marcy, G. W.; Winn, J. N.; Sipőcz, B.; Lázár, J.; Papp, I.; Sári, P. 2007-11-01 We report the discovery of a massive (Mp=9.04+/-0.50 MJ) planet transiting the bright (V=8.7) F8 star HD 147506, with an orbital period of 5.63341+/-0.00013 days and an eccentricity of e=0.520+/-0.010. From the transit light curve we determine that the radius of the planet is Rp=0.982+0.038-0.105 RJ. HD 147506b (also coined HAT-P-2b) has a mass about 9 times the average mass of previously known transiting exoplanets and a density of ρp~12 g cm-3, greater than that of rocky planets like the Earth. Its mass and radius are marginally consistent with theories of structure of massive giant planets composed of pure H and He, and accounting for them may require a large (>~100 M⊕) core. The high eccentricity causes a ninefold variation of insolation of the planet between peri- and apastron. Using follow-up photometry, we find that the center of transit is Tmid=2,454,212.8559+/-0.0007 (HJD) and the transit duration is 0.177+/-0.002 days. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Keck time has been in part granted by NASA. 15. A resolved, au-scale gas disk around the B[e] star HD 50138 Science.gov (United States) Ellerbroek, L. E.; Benisty, M.; Kraus, S.; Perraut, K.; Kluska, J.; le Bouquin, J. B.; Borges Fernandes, M.; Domiciano de Souza, A.; Maaskant, K. M.; Kaper, L.; Tramper, F.; Mourard, D.; Tallon-Bosc, I.; ten Brummelaar, T.; Sitko, M. L.; Lynch, D. K.; Russell, R. W. 2015-01-01 HD 50138 is a B[e] star surrounded by a large amount of circumstellar gas and dust. Its spectrum shows characteristics which may indicate either a pre- or a post-main-sequence system. Mapping the kinematics of the gas in the inner few au of the system contributes to a better understanding of its physical nature. We present the first high spatial and spectral resolution interferometric observations of the Brγ line of HD 50138, obtained with VLTI/AMBER. The line emission originates in a region more compact (up to 3 au) than the continuum-emitting region. Blue- and red-shifted emission originates from the two different hemispheres of an elongated structure perpendicular to the polarization angle. The velocity of the emitting medium decreases radially. An overall offset along the NW direction between the line- and continuum-emitting regions is observed. We compare the data with a geometric model of a thin Keplerian disk and a spherical halo on top of a Gaussian continuum. Most of the data are well reproduced by this model, except for the variability, the global offset and the visibility at the systemic velocity. The evolutionary state of the system is discussed; most diagnostics are ambiguous and may point either to a post-main-sequence or a pre-main-sequence nature. Based on observations performed with X-Shooter (program 090.D-0212) and CRIRES (program 084.C-0668), mounted on the ESO Very Large Telescope, on Cerro Paranal, Chile, and AMBER mounted on the Very Large Telescope Interferometer (programs 082.C-0621, 082.C-0657, 083.C-0144, 084.C-0187, 084.C-0668, 084.C-0983, 384.D-0482, and 092.C-0376(B)).Figure 4 and Appendix A are available in electronic form at http://www.aanda.org 16. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370 ★ Science.gov (United States) Hrudková, M.; Hatzes, A.; Karjalainen, R.; Lehmann, H.; Hekker, S.; Hartmann, M.; Tkachenko, A.; Prins, S.; Van Winckel, H.; De Nutte, R.; Dumortier, L.; Frémat, Y.; Hensberge, H.; Jorissen, A.; Lampens, P.; Laverick, M.; Lombaert, R.; Pápics, P. I.; Raskin, G.; Sódor, Á.; Thoul, A.; Van Eck, S.; Waelkens, C. 2016-09-01 We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 ± 1.0 MJupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our program to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coudé echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph HERMES of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 ± 4.5 days) variation with a semi-amplitude K = 133 ± 25 ms-1, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ˜88 years in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-amplitude radial velocity variations and only future continued monitoring of this system may answer this uncertainty. From Kepler photometry we find that HD 175370 is most likely a low-mass red-giant branch or asymptotic-giant branch star. 17. An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star CERN Document Server Santos, N C; Faria, J P; Rey, J; Correia, A C M; Laskar, J; Udry, S; Adibekyan, V; Bouchy, F; Delgado-Mena, E; Melo, C; Dumusque, X; Hébrard, G; Lovis, C; Mayor, M; Montalto, M; Mortier, A; Pepe, F; Figueira, P; Sahlmann, J; Ségransan, D; Sousa, S G 2016-01-01 With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1years) massive (msini=15.1MJup) companion (HD219828c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD219828b, with a minimum mass of 21 MEarth and a period of 3.83days. The dynamical analysis shows that the system is stable. The HD219828 system is extreme and unique in several aspects. First, among all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like H... 18. Velocity Curve Analysis of Spectroscopic Binary Stars AI Phe, GM Dra, HD 93917 and V502 Oph by Nonlinear Regression Institute of Scientific and Technical Information of China (English) 2007-01-01 We introduce a new method to derive the orbital parameters of spectroscopic binary stars by nonlinear least squares of (o - c). Using the measured radial velocity data of the four double lined spectroscopic binary systems,AI Phe,GM Dra,HD 93917 and V502 Oph,we derived both the orbital and combined spectroscopic elements of these systems.Our numerical results are in good agreement with the those obtained using the method of Lehmann-Filhés. 19. Imaging an 80 au Radius Dust Ring around the F5V Star HD 157587 Science.gov (United States) Millar-Blanchaer, Maxwell A.; Wang, Jason J.; Kalas, Paul; Graham, James R.; Duchêne, Gaspard; Nielsen, Eric L.; Perrin, Marshall; Moon, Dae-Sik; Padgett, Deborah; Metchev, Stanimir; Ammons, S. Mark; Bailey, Vanessa P.; Barman, Travis; Bruzzone, Sebastian; Bulger, Joanna; Chen, Christine H.; Chilcote, Jeffrey; Cotten, Tara; De Rosa, Robert J.; Doyon, Rene; Draper, Zachary H.; Esposito, Thomas M.; Fitzgerald, Michael P.; Follette, Katherine B.; Gerard, Benjamin L.; Greenbaum, Alexandra Z.; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Johnson-Groh, Mara; Konopacky, Quinn; Larkin, James E.; Macintosh, Bruce; Maire, Jérôme; Marchis, Franck; Marley, Mark S.; Marois, Christian; Matthews, Brenda C.; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rajan, Abhijith; Rameau, Julien; Rantakyrö, Fredrik T.; Savransky, Dmitry; Schneider, Adam C.; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J. Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler 2016-11-01 We present H-band near-infrared polarimetric imaging observations of the F5V star HD 157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of ∼80–100 au. The new GPI data complement recent Hubble Space Telescope/STIS observations that show the disk extending out to over 500 au. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry, we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of ∼70° and a 1.5 ± 0.6 au stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the form of the scattering phase function and remains poorly constrained. The disk is not recovered in total intensity due in part to strong adaptive optics residuals, but we recover three point sources. Considering the system’s proximity to the galactic plane and the point sources’ positions relative to the disk, we consider it likely that they are background objects and unrelated to the disk’s offset from the star. 20. Periods of magnetic field variations in the Ap star$\\gamma$Equulei (HD 201601) CERN Document Server Bychkov, V D; Madej, J 2015-01-01 This paper presents a series of 95 new measurements of the longitudinal (effective) magnetic field$B_e$of the Ap star$\\gamma$Equ (HD 201601). Observations were obtained at the coud\\'e focus of the 1-m reflector at the Special Astrophysical Observatory (SAO RAS) in Russia over a time period of 4190 days (more than 11 years). We compiled a long record of$B_e$points, adding our measurements to all published data. The time series of magnetic data consists of 395$B_e$points extending for 24488 days, or over 67 years. Various methods of period determination were examined for the case in which the length of the observed time series is rather short and amounts only to ~69 percent of the period. We argue that the fitting of a sine wave to the observed$B_e$points by least squares yields the most reliable period in the case of$\\gamma$Equ. Therefore, the best period for long-term magnetic variations of$\\gamma$Equ, and hence the rotational period, is$P_{\\rm rot}=35462.5 \\pm 1149$days$= 97.16 \\pm 3.15$yea... 1. Determination of mass and orbital parameters of a low-mass star HD 213597B CERN Document Server Chaturvedi, Priyanka; Dixit, Vaibhav; Roy, Arpita; Chakraborty, Abhijit; Mahadevan, Suvrath; Anandarao, B G; Hebb, Leslie; Janardhan, P 2014-01-01 HD 213597 is an eclipsing binary system which was detected by the STEREO spacecraft and was speculated to host a low-mass stellar companion. We used high-resolution spectroscopy with the 10-m Hobby-Eberly Telescope and the 1.2-m telescope in Mt Abu for radial velocity (RV) measurements of this source. We performed aperture photometry for this star on the STEREO archival data and thereby confirm the transit signature. We also did follow-up ground-based photometry with a 10-inch telescope from Mt Abu. The spectroscopic RV semi-amplitude of the primary (33.39 km s^-1) indicates that the secondary is an M dwarf making the system a short period F+M eclipsing binary. These RVs along with the inclination derived from our combined photometric analysis (i=84.9 degree), enable us to estimate the mass of the secondary as M_B ~ 0.286 M_sun and radius as R_B ~ 0.344 R_sun using an estimated mass M_A ~ 1.3 M_sun and radius R_B ~ 1.97 R_sun of the primary. Our spectral analysis returned the following parameters: T_eff = 662... 2. Photospheric and chromospheric activity on the young solar-type star HD 171488 CERN Document Server Frasca, A; Kovari, Zs; Marilli, E; Cakirli, O 2010-01-01 We present the results of contemporaneous spectroscopic and photometric monitoring of the young solar-type star HD171488 (Prot~1.337 d) aimed at studying surface inhomogeneities at photospheric/chromospheric levels. Echelle FOCES spectra (R~40000) and Johnson photometry have been performed in 2006. Spectral type, rotational velocity, metallicity, and gravity were determined using a code developed by us. The metallicity was measured from the analysis of iron lines. The spectral subtraction technique was applied to the most relevant chromospheric diagnostics included in the FOCES spectral range (CaII IRT, Halpha, HeI-D3, Hbeta, CaII H&K). A model with two large high-latitude spots is sufficient to reproduce the B/V light curves and the radial velocity modulation, if a temperature difference between photosphere and spots of 1500 K is used. A Doppler imaging analysis of photospheric lines confirms a similar spot distribution. With the help of an analogous geometric two-spot model, we are able to reproduce the... 3. Analysis of the circumstellar environment of the B[e] star HD 45677 (FS CMa) CERN Document Server Muratorio, G; Friedjung, M; Rossi, Corinne; Friedjung, Michael 2006-01-01 We studied the circumstellar environment of the B[e] star HD 45677 through the analysis of the emission lines from ionized metals. We used the statistical approach of the self absorption curve method (SAC) to derive physical parameters of the line emitting region. The Fe II and Cr II double-peaked emission line structure is explained by the presence of a thin absorption component red shifted by ~3 km/s. This absorption component can be interpreted geometricaly as being due to infalling material perpendicularly to the disk seen nearly pole-on, as indicated by the emission line structure. The Cr II and Fe II emission lines have a complex structure with two (narrow and broad) components, of 45 and 180 km/s FWHM for the permitted lines and 25 and 100 km/s FWHM for the forbidden ones, respectively. We argue that the narrow components are principaly emitted by an optically thin disk seen nearly pole-on, in a region whose minimum radius is estimated to be 4 10^12 cm, while the broad ones are formed in a disk-linked ... 4. An icy Kuiper-Belt around the young solar-type star HD 181327 CERN Document Server Lebreton, J; Thi, W -F; Roberge, A; Donaldson, J; Schneider, G; Maddison, S T; Ménard, F; Riviere-Marichalar, P; Mathews, G S; Kamp, I; Pinte, C; Dent, W R F; Barrado, D; Duchêne, G; Gonzalez, J -F; Grady, C A; Meeus, G; Pantin, E; Williams, J P; Woitke, P 2011-01-01 HD 181327 is a young F5/F6V star belonging to the Beta Pictoris moving group (12 Myr). It harbors an optically thin belt of circumstellar material at 90 AU. We aim to study the dust properties in the belt in details, and to constrain the gas-to-dust ratio. We obtained far-IR observations with the Herschel/PACS instrument, and 3.2 mm observations with the ATCA array. The geometry of the belt is constrained with newly reduced HST/NICMOS images that break the degeneracy between the disk geometry and the dust properties. We use the radiative transfer code GRaTer to compute a large grid of models, and we identify the grain models that best reproduce the Spectral Energy Distribution through a Bayesian analysis. We attempt to detect the [OI] and [CII] lines with PACS spectroscopy, providing observables to our photochemical code ProDiMo. The HST observations confirm that the dust is confined in a narrow belt. The continuum is detected in the far-IR with PACS and the disk is resolved with both PACS and ATCA. A medium ... 5. Imaging an 80 AU Radius Dust Ring Around the F5V Star HD 157587 CERN Document Server Millar-Blanchaer, Maxwell A; Kalas, Paul; Graham, James R; Duchene, Gaspard; Nielsen, Eric L; Perrin, Marshall; Moon, Dae-Sik; Padgett, Deborah; Metchev, Stanimir; Ammons, S Mark; Bailey, Vanessa P; Barman, Travis; Bruzzone, Sebastian; Bulger, Joanna; Chen, Christine H; Chilcote, Jeffrey; Cotten, Tara; De Rosa, Robert J; Doyon, Rene; Draper, Zachary H; Esposito, Thomas M; Fitzgerald, Michael P; Follette, Katherine B; Gerard, Benjamin L; Greenbaum, Alexandra Z; Hibon, Pascale; Hinkley, Sasha; Hung, Li-Wei; Ingraham, Patrick; Johnson-Groh, Mara; Konopacky, Quinn; Larkin, James E; Macintosh, Bruce; Maire, Jerome; Marchis, Franck; Marley, Mark S; Marois, Christian; Matthews, Brenda C; Oppenheimer, Rebecca; Palmer, David; Patience, Jennifer; Poyneer, Lisa; Pueyo, Laurent; Rajan, Abhijith; Rameau, Julien; Rantakyro, Fredrik T; Savransky, Dmitry; Schneider, Adam C; Sivaramakrishnan, Anand; Song, Inseok; Soummer, Remi; Thomas, Sandrine; Vega, David; Wallace, J Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane; Wolff, Schuyler 2016-01-01 We present$H$-band near-infrared polarimetric imaging observations of the F5V star HD~157587 obtained with the Gemini Planet Imager (GPI) that reveal the debris disk as a bright ring structure at a separation of$\\sim$80$-$100~AU. The new GPI data complement recent HST/STIS observations that show the disk extending out to over 500~AU. The GPI image displays a strong asymmetry along the projected minor axis as well as a fainter asymmetry along the projected major axis. We associate the minor and major axis asymmetries with polarized forward scattering and a possible stellocentric offset, respectively. To constrain the disk geometry we fit two separate disk models to the polarized image, each using a different scattering phase function. Both models favor a disk inclination of$\\sim 70\\degr$and a$1.5\\pm0.6$AU stellar offset in the plane of the sky along the projected major axis of the disk. We find that the stellar offset in the disk plane, perpendicular to the projected major axis is degenerate with the for... 6. ALMA Observations of the Molecular Gas in the Debris Disk of the 30 Myr Old Star HD 21997 Science.gov (United States) Kospal, A.; Moor, A.; Juhasz, A.; Abraham, P.; Apai, D.; Csengeri, T.; Grady, C. A.; Henning, Th.; Hughes, A. M.; Kiss, Cs.; Pascucci, I.; Schmalzl, M. 2013-01-01 The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here, we report on the detection of (12)CO and (13)CO in the J = 2-1 and J = 3-2 transitions and C(18)O in the J = 2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r(sub in) star. We explore two possible scenarios for the origin of the gas. A secondary origin, which involves gas production from colliding or active planetesimals, would require unreasonably high gas production rates and would not explain why the gas and dust are not colocated. We propose that HD 21997 is a hybrid system where secondary debris dust and primordial gas coexist. HD 21997, whose age exceeds both the model predictions for disk clearing and the ages of the oldest T Tauri-like or transitional gas disks in the literature, may be a key object linking the primordial and the debris phases of disk evolution. 7. A spectroscopic survey of Herbig Ae/Be stars with X-Shooter II: Accretion diagnostic lines CERN Document Server Fairlamb, John R; Mendigutia, Ignacio; Ilee, John D; Ancker, Mario E van den 2016-01-01 The Herbig Ae/Be stars (HAeBes) allow an exploration of the properties of Pre-Main Sequence(PMS) stars above the low-mass range ($8{\\rm\\thinspace M_{\\odot}}$). This paper is the second in a series exploring accretion in 91 HAeBes with Very Large Telescope/X-shooter spectra. Equivalent width measurements are carried out on 32 different lines, spanning the UV to NIR, in order to obtain their line luminosities. The line luminosities were compared to accretion luminosities, which were determined directly from measurements of an UV-excess. When detected, emission lines always demonstrate a correlation with the accretion luminosity, regardless of detection frequency. The average relationship between accretion luminosity and line luminosity is found to be${\\thinspace L_{\\rm acc}}\\propto{\\thinspace L_{\\rm line}}^{1.16 \\pm 0.15}$. This is in agreement with the findings in Classical T Tauri stars, although the HAeBe relationship is generally steeper, particularly towards the Herbig Be mass range. Since all observed li... 8. Large dust gaps in the transitional disks of HD 100453 and HD 34282 CERN Document Server Khalafinejad, S; Marinas, N; Tielens, A G G M 2015-01-01 The formation of dust gaps in protoplanetary disks is one of the most important signposts of disk evolution and possibly the formation of planets. We aim to characterize the 'flaring' disk structure around the Herbig Ae/Be stars HD 100453 and HD 34282. Their spectral energy distributions (SEDs) show an emission excess between 15-40{\\mu}m, but very weak (HD 100453) and no (HD 34282) signs of the 10 and 20 {\\mu}m amorphous silicate features. We investigate whether this implies the presence of large dust gaps. In this work, spatially resolved mid-infrared Q-band images taken with Gemini North/MICHELLE are investigated. We perform radiative transfer modeling and examine the radial distribution of dust. We simultaneously fit the Q-band images and SEDs of HD 100453 and HD 34282. Our solutions require that the inner-halos and outer-disks are likely separated by large dust gaps that are depleted wih respect to the outer disk by a factor of 1000 or more. The inner edges of the outer disks of HD 100453 and HD 34282 hav... 9. Brackett γ radiation from the inner gaseous accretion disk, magnetosphere, and disk wind region of Herbig AeBe stars Science.gov (United States) Tambovtseva, L. V.; Grinin, V. P.; Weigelt, G. 2016-05-01 Various disk and outflow components such as the magnetosphere, the disk wind, the gaseous accretion disk, and other regions may contribute to the hydrogen line emission of young Herbig AeBe stars. Non-LTE modeling was performed to show the influence of the model parameters of each emitting region on the intensity and shape of the Brγ line profile, to present the spatial brightness distribution of each component, and to compare the contribution of each component to the total line emission. The modeling shows that the disk wind is the dominant contributor to the Brγ line rather than the magnetosphere and inner gaseous accretion disk. The contribution of the disk wind region to the Hα line is also considered. 10. The Foggy Disks Surrounding Herbig Ae Stars: a Theoretical Study of the H2O Line Spectra CERN Document Server Cernicharo, J; Ménard, F; Pinte, C; Fuente, A 2009-01-01 Water is a key species in many astrophysical environments, but it is particularly important in proto-planetary disks. So far,observations of water in these objects have been scarce, but the situation should soon change thanks to the Herschel satellite. We report here a theoretical study of the water line spectrum of a proto-planetary disk surrounding Ae stars. We show that several lines will be observable with the HIFI instrument onboard the Herschel Space Observatory. We predict that some maser lines could also be observable with ground telescopes and we discuss how the predictions depend not only on the adopted physical and chemical model but also on the set of collisional coefficients used and on the H2 ortho to para ratio through its effect on collisional excitation. This makes the water lines observations a powerful, but dangerous -if misused- diagnostic tool. 11. Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150, and HD 46966 Science.gov (United States) Blomme, R.; Mahy, L.; Catala, C.; Cuypers, J.; Gosset, E.; Godart, M.; Montalban, J.; Ventura, P.; Rauw, G.; Morel, T.; Degroote, P.; Aerts, C.; Noels, A.; Michel, E.; Baudin, F.; Baglin, A.; Auvergne, M.; Samadi, R. 2011-09-01 Context. The detection of pulsational frequencies in stellar photometry is required as input for asteroseismological modelling. The second short run (SRa02) of the CoRoT mission has provided photometric data of unprecedented quality and time-coverage for a number of O-type stars. Aims: We analyse the CoRoT data corresponding to three hot O-type stars, describing the properties of their light curves and search for pulsational frequencies, which we then compare to theoretical model predictions. Methods: We determine the amplitude spectrum of the data, using the Lomb-Scargle and a multifrequency HMM-like technique. Frequencies are extracted by prewhitening, and their significance is evaluated under the assumption that the light curve is dominated by red noise. We search for harmonics, linear combinations, and regular spacings among these frequencies. We use simulations with the same time sampling as the data as a powerful tool to judge the significance of our results. From the theoretical point of view, we use the MAD non-adiabatic pulsation code to determine the expected frequencies of excited modes. Results: A substantial number of frequencies is listed, but none can be convincingly identified as being connected to pulsations. The amplitude spectrum is dominated by red noise. Theoretical modelling shows that all three O-type stars can have excited modes, but the relation between the theoretical frequencies and the observed spectrum is not obvious. Conclusions: The dominant red noise component in the hot O-type stars studied here clearly points to a different origin than the pulsations seen in cooler O stars. The physical cause of this red noise is unclear, but we speculate on the possibility of sub-surface convection, granulation, or stellar wind inhomogeneities being responsible. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany and Spain 12. The evolved B[e] star HD 87643 observations and a radiation driven disk-wind model for B[e] stars CERN Document Server Oudmaijer, R D; Drew, J E; De Winter, D; Oudmaijer, Rene; Proga, Daniel; Drew, Janet; Winter, Dolf de 1998-01-01 New high resolution spectroscopic and medium resolution spectropolarimetric data, complemented with optical broad and narrow band imaging, of the B[e] star HD 87643 are presented. The spectrum of HD 87643 exhibits the hybrid characteristics well known to be representative of the group of B[e] stars; a fast wind with an expansion velocity in excess of 1000 km/s is measured in the hydrogen and helium lines, while a slower component is traced by lower excitation lines and forbidden lines. Clues to the geometry of the rapidly expanding circumstellar shell are provided by the startling polarization changes across Halpha. Comparison with published schematic calculations indicates that the polarizing material is located in a slowly rotating, expanding disk structure. A hydrodynamical model is then presented whose results are consistent with the original two-wind concept for B[e] stars and exhibits kinematic properties that may well explain the observed spectral features in HD 87643. The model calculations use as inp... 13. Accretion rates and accretion tracers of Herbig Ae/Be stars CERN Document Server Mendigutía, I; Montesinos, B; Mora, A; Muzerolle, J; Eiroa, C; Oudmaijer, R D; Merín, B 2011-01-01 This work aims to derive accretion rates for a sample of 38 HAeBe stars. We apply magnetospheric accretion (MA) shock modelling to reproduce the observed Balmer excesses. We look for possible correlations with the strength of the Halpha, [OI]6300, and Brgamma emission lines. The median mass accretion rate is 2 x 10^-7 Msun yr^-1 in our sample. The model fails to reproduce the large Balmer excesses shown by the four hottest stars (T* > 12000 K). We derive Macc propto M*^5 and Lacc propto L*^1.2 for our sample, with scatter. Empirical calibrations relating the accretion and the Halpha, [OI]6300, and Brgamma luminosities are provided. The slopes in our expressions are slightly shallower than those for lower mass stars, but the difference is within the uncertainties, except for the [OI]6300 line. The Halpha 10% width is uncorrelated with Macc, unlike for the lower mass regime. The mean Halpha width shows higher values as the projected rotational velocities of HAe stars increase, which agrees with MA. The accretio... 14. Magnetic fields and differential rotation on the pre-main sequence III: The early-G star HD 106506 CERN Document Server Waite, I A; Carter, B D; Hart, R; Donati, J -F; Vélez, J C Ramírez; Semel, M; Dunstone, N 2011-01-01 We present photometry and spectropolarimetry of the pre-main sequence star HD 106506. A photometric rotational period of ~1.416 +/- 0.133 days has been derived using observations at Mount Kent Observatory (MKO). Spectropolarimetric data taken at the 3.9-m Anglo-Australian Telescope (AAT) were used to derive spot occupancy and magnetic maps of the star through the technique of Zeeman Doppler imaging (ZDI). The resulting brightness maps indicate that HD 106506 displays photospheric spots at all latitudes including a predominant polar spot. Azimuthal and radial magnetic images of this star have been derived, and a significant azimuthal magnetic field is indicated, in line with other active young stars. A solar-like differential rotation law was incorporated into the imaging process. Using Stokes I information the equatorial rotation rate,$\\Omega_{eq}$, was found to be 4.54 +/- 0.01 rad/d, with a photospheric shear$\\delta\\Omega$of$0.21_{-0.03}^{+0.02}$rad/d. This equates to an equatorial rotation period of ~... 15. Parameters of Herbig Ae/Be and Vega-type stars CERN Document Server Montesinos, Benjamin; Mora, Alcione; Merin, Bruno 2008-01-01 This work presents the determination of the effective temperature, gravity, metallicity, mass, luminosity and age of 27 young early-type stars, most of them in the age range 1-10 Myr, and three -suspected- hot companions of post-T Tauri stars belonging to the Lindroos binary sample. Most of these objects show IR excesses in their spectral energy distributions, which are indicative of the presence of disks. The work is relevant in the fields of stellar physics, physics of disks and formation of planetary systems. Spectral energy distributions and mid-resolution spectra were used to estimate the effective temperature. The comparison of the profiles of the Balmer lines with synthetic profiles provides the value of the stellar gravity. High-resolution optical observations and synthetic spectra are used to estimate the metallicity, [M/H]. Once these three parameters are known for each star, evolutionary tracks and isochrones provide estimations of the mass, luminosity, age and distance (or upper limits in some cas... 16. Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars Science.gov (United States) Ababakr, K. M.; Oudmaijer, R. D.; Vink, J. S. 2016-09-01 We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560-9480 Å, published to date. A change in linear polarization across the H α line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small discs around these accreting objects. Thanks to the large wavelength coverage, we can report that H α is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarization in such cases. Few other spectral lines display changes in polarization across the line. In addition, H α is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and demonstrate that the detection of the line effect strongly relies on the number of photons scattered into our line of sight. We highlight the special case of R Mon, which is the only object in our sample to show many lines with a polarization effect, which is much stronger than in all other objects. Given that the object and its nebulosity is spatially resolved, we argue that this is due to scattering of the stellar and emission spectrum off circumstellar dust. 17. Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars CERN Document Server Ababakr, K M; Vink, J S 2016-01-01 We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560 {\\AA} to 9480 {\\AA}, published to date. A change in linear polarisation across the H{\\alpha} line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small disks around these accreting objects. Thanks to the large wavelength coverage, we can report that H{\\alpha} is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarisation in such cases. Few other spectral lines display changes in polarisation across the line. In addition, H{\\alpha} is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and de... 18. The ultraviolet lines of carbon, nitrogen, and oxygen in the IUE spectrum of the field horizontal-branch A star HD 109995 Science.gov (United States) Leckrone, David S.; Adelman, Saul J. 1986-01-01 Photospheric abundances of C, N and O of an evolved halo Population 2 star, the field horizontal-branch star HD 109995, based on observations of ultraviolet resonance or low excitation lines are presented. The logarithmic abundance ratio with respect to the Sun O/Fe = +1.5 is substantially higher than previously determined values for Pop. 2 red giants or RR Lyrae stars, but agrees well with a derived value from the OI infrared triplet. This may be direct evidence of Tinsley's (1979) scenario of localized sharply rising interstellar oxygen abundances immediately following bursts of massive star formation. Star HD 109995 may have formed from such highly oxygen-enriched material prior to its dilution by gas with the pre-burst composition. The ratio C/N = -1.3 may reflect the composition of material from which the star formed or CN processing within the star during its evolution. 19. The nature of the high Galactic latitude O-star HD93521: new results from X-ray and optical spectroscopy CERN Document Server Rauw, Gregor; Palate, Matthieu 2012-01-01 Owing to its unusual location and its isolation, the nature of the high Galactic latitude O9.5Vp object HD93521 is still uncertain. We have collected X-ray and optical observations to characterize the star and its surroundings. X-ray images and spectra are analyzed to search for traces of a recent star formation event around HD93521 and to search for the signature of a possible compact companion. Optical echelle spectra are analysed with plane-parallel model atmosphere codes, assuming either a spherical star or a gravity darkened rotationally flattened star, to infer the effective temperature and surface gravity, and to derive the He, C, N and O abundances of HD93521. The X-ray images reveal no traces of a population of young low-mass stars coeval with HD93521. The X-ray spectrum of HD93521 is consistent with a normal late O-type star although with subsolar metallicity. No trace of a compact companion is found in the X-ray data. In the optical spectrum, He and N are found to be overabundant, in line with the ... 20. Accretion-related properties of Herbig Ae/Be stars. Comparison with T Tauris CERN Document Server Mendigutía, I; Montesinos, B; Eiroa, C; Meeus, G; Merín, B; Oudmaijer, R D 2012-01-01 We look for trends relating the mass accretion rate (Macc) and the stellar ages (t), spectral energy distributions (SEDs), and disk masses (Mdisk) for a sample of 38 HAeBe stars, comparing them to analogous correlations found for classical T Tauri stars. Our goal is to shed light on the timescale and physical processes that drive evolution of intermediate-mass pre-main sequence objects. Macc shows a dissipation timescale \\tau = 1.3^{+1.0}_{-0.5} Myr from an exponential law fit, while a power law yields Macc(t) \\propto t^{-\\eta}, with \\eta = 1.8^{+1.4}_{-0.7}. This result is based on our whole HAeBe sample (1-6 Msun), but the accretion rate decline most probably depends on smaller stellar mass bins. The near-IR excess is higher and starts at shorter wavelengths (J and H bands) for the strongest accretors. Active and passive disks are roughly divided by 2 x 10^{-7} Msun/yr. The mid-IR excess and the SED shape from the Meeus et al. classification are not correlated with Macc. We find Macc \\propto Mdisk^{1.1 +- 0... 1. Herbig Ae/Be candidate stars in the innermost Galactic disk: Quartet cluster CERN Document Server Yasui, Chikako; Hamano, Satoshi; Kondo, Sohei; Izumi, Natsuko; Saito, Masao; Tokunaga, Alan T 2016-01-01 In order to investigate the Galactic-scale environmental effects on the evolution of protoplanetary disks, we explored the near-infrared (NIR) disk fraction of the Quartet cluster, which is a young cluster in the innermost Galactic disk at the Galactocentric radius Rg ~ 4 kpc. Because this cluster has a typical cluster mass of ~10^3 M_sun as opposed to very massive clusters, which have been observed in previous studies (>10^4 M_sun), we can avoid intra-cluster effects such as strong UV field from OB stars. Although the age of the Quartet is previously estimated to be 3-8 Myr old, we find that it is most likely ~3-4.5 Myr old. In moderately deep JHK images from the UKIDSS survey, we found eight HAeBe candidates in the cluster, and performed K-band medium-resolution ($R \\equiv \\Delta \\lambda / \\lambda ~ 800$) spectroscopy for three of them with the Subaru 8.2 m telescope. These are found to have both Br\\gamma absorption lines as well as CO bandhead emission, suggesting that they are HAeBe stars with protoplanet... 2. VizieR Online Data Catalog: Variability of the PGa star HD 19400 (Hubrig+, 2014) Science.gov (United States) Hubrig, S.; Castelli, F.; Gonzalez, J. F.; Carroll, T. A.; Ilyin, I.; Schoeller, M.; Drake, N. A.; Korhonen, H.; Briquet, M. 2014-07-01 Table 3 contains line by line abundances of HD19400 from the ATLAS12 model with parameters Teff=13500K and logg=3.9. The spectropolarimetric observations of HD 19400 have been obtained with the HARPS instrument attached to ESO's 3.6m telescope at La Silla during 3 nights: 2011-12-15, 2011-12-16, and 2013-07-19. (2 data files). 3. Confirming HD 23478 as a new magnetic B star hosting an H$\\alpha$-bright centrifugal magnetosphere CERN Document Server Sikora, James; Bohlender, David; Neiner, Coralie; Oksala, Mary; Shultz, Matt; Cohen, David; ud-Doula, Asif; Grunhut, Jason; Monin, Dmitry; Owocki, Stan; Petit, Véronique; Rivinius, Thomas; Townsend, Richard 2015-01-01 In this paper we report 23 magnetic field measurements of the B3IV star HD 23478: 12 obtained from high resolution Stokes$V$spectra using the ESPaDOnS (CFHT) and Narval (TBL) spectropolarimeters, and 11 from medium resolution Stokes$V$spectra obtained with the DimaPol spectropolarimeter (DAO). HD 23478 was one of two rapidly rotating stars identified as potential "centrifugal magnetosphere" hosts based on IR observations from the Apache Point Observatory Galactic Evolution Experiment survey. We derive basic physical properties of this star including its mass ($M=6.1^{+0.8}_{-0.7}\\,M_\\odot$), effective temperature ($T_{\\rm eff}=20\\pm2\\,$kK), radius ($R=2.7^{+1.6}_{-0.9}\\,R_\\odot$), and age ($\\tau_{\\rm age}=3^{+37}_{-1}\\,$Myr). We repeatedly detect weakly-variable Zeeman signatures in metal, He and H lines in all our observations corresponding to a longitudinal magnetic field of$\\langle B_z\\rangle\\approx-2.0\\,$kG. The rotational period is inferred from Hipparcos photometry ($P_{\\rm rot}=1.0498(4)\\,$d). Und... 4. Detection of Elements at All Three r-process Peaks in the Metal-Poor Star HD 160617 CERN Document Server Roederer, Ian U; 10.1088/0004-637X/750/1/76 2012-01-01 We report the first detection of elements at all three r-process peaks in the metal-poor halo star HD 160617. These elements include arsenic and selenium, which have not been detected previously in halo stars, and the elements tellurium, osmium, iridium, and platinum, which have been detected previously. Absorption lines of these elements are found in archive observations made with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. We present up-to-date absolute atomic transition probabilities and complete line component patterns for these elements. Additional archival spectra of this star from several ground-based instruments allow us to derive abundances or upper limits of 45 elements in HD 160617, including 27 elements produced by neutron-capture reactions. The average abundances of the elements at the three r-process peaks are similar to the predicted solar system r-process residuals when scaled to the abundances in the rare earth element domain. This result for arsenic and selen... 5. The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370 CERN Document Server Hrudková, M; Karjalainen, R; Lehmann, H; Hekker, S; Hartmann, M; Tkachenko, A; Prins, S; van Winckel, H; de Nutte, R; Dumortier, L; Frémat, Y; Hensberge, H; Jorissen, A; Lampens, P; Laverick, M; Lombaert, R; Pápics, P I; Raskin, G; Sódor, Á; Thoul, A; van Eck, S; Waelkens, C 2016-01-01 We report on the discovery of a planetary companion candidate with a minimum mass Msini = 4.6 M_J orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our program to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coude echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph HERMES of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 days) variation with a semi-amplitude K = 133 m/s, superimposed on a long-term trend. A low-mass stellar companion with an orbital period of ~88 years in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-... 6. HD5980 Science.gov (United States) Koenigsberger, C. HD5980 is a multiple system containing at least 3 very massive and luminous stars. Located in the Small Magellanic Cloud, it is an ideal system for studying the massive star structure and evolutionary processes in low-metallicity environments. Intensely observed over the past few decades, HD5980 is a treasure trove of information on stellar wind structure, on wind-wind collisions and on the formation of wind-blown circumstellar structures. In addition, its characteristics suggest that the eclipsing WR+LBV stars of the system are the product of quasihomogeneous chemical evolution, thus making them candidate pair production supernovae or GRB progenitors. This paper summarizes some of the outstanding results derived from half a century of observations and recent theoretical studies. 7. An extreme planetary system around HD 219828. One long-period super Jupiter to a hot-Neptune host star Science.gov (United States) Santos, N. C.; Santerne, A.; Faria, J. P.; Rey, J.; Correia, A. C. M.; Laskar, J.; Udry, S.; Adibekyan, V.; Bouchy, F.; Delgado-Mena, E.; Melo, C.; Dumusque, X.; Hébrard, G.; Lovis, C.; Mayor, M.; Montalto, M.; Mortier, A.; Pepe, F.; Figueira, P.; Sahlmann, J.; Ségransan, D.; Sousa, S. G. 2016-07-01 Context. With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. This wide diversity provides fundamental clues to the processes of planet formation and evolution. Aims: We present a full investigation of the HD 219828 system, a bright metal-rich star for which a hot Neptune has previously been detected. Methods: We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD 219828. The spectra were used to characterise the star and its chemical abundances, as well as to check for spurious, activity induced signals. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. Results: We announce the discovery of a long period (P = 13.1 yr) massive (m sini = 15.1 MJup) companion (HD 219828 c) in a very eccentric orbit (e = 0.81). The same data confirms the existence of a hot Neptune, HD 219828 b, with a minimum mass of 21 M⊕ and a period of 3.83 days. The dynamical analysis shows that the system is stable, and that the equilibrium eccentricity of planet b is close to zero. Conclusions: The HD 219828 system is extreme and unique in several aspects. First, ammong all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD 219828, with a hot Neptune and a long-period massive companion are more frequent than similar systems with a hot Jupiter instead. This suggests that the formation of hot Neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD 219828 c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD 219828 b is detected 8. The Disk and Wind of HD 104237 Science.gov (United States) Danks, Anthony 2000-07-01 STIS GTO studies of intermediate-mass stars have revealed circumstellar disks and associated nebulosities in 44% of our sample. The largest-scale nebulosity is seen in those systems with emission in the unidentified infrared bands, which have been interpreted as being associated with C-H stretch and bend modes in small organic grains {sometimes interpreted as polycyclic aromatic hydrocarbons}. We wish to test this hypothesis with coronagraphic observations of the nearby Herbig Ae star, HD 104237 {d=115pc} which shows UIB features in its ISO SWS spectrum. This system is also known to have lyman alpha in emission, and is thus a prime candidate for mapping the spatial extent of the wind and to search for the presence of a collimated outflow similar to that seen in HD 163296. We will follow up on the coronagraphic imaging with a G140M long slit spectrum at Lyman alpha, and a G140L spectrum. 9. Revealing the Asymmetry of the Wind of the Variable Wolf-Rayet Star WR1 (HD4004) Through Spectropolarization OpenAIRE St-Louis, Nicole 2013-01-01 In this paper, high quality spectropolarimetric observations of the Wolf-Rayet (WR) Star WR1 (HD4004) obtained with ESPaDOnS at CFHT are presented. All major emission lines present in the spectrum show depolarization in the relative Stokes parameters Q/I and U/I. From the behaviour of the amount of line depolarization as a function of line strength, the intrinsic continuum light polarization of WR1 is estimated to be P/I=0.443 \\pm 0.028 % with an angle of \\theta=-26.2^o. Although such a level... 10. A HOT URANUS ORBITING THE SUPER METAL-RICH STAR HD 77338 AND THE METALLICITY-MASS CONNECTION Energy Technology Data Exchange (ETDEWEB) Jenkins, J. S.; Hoyer, S.; Jones, M. I.; Rojo, P.; Day-Jones, A. C.; Ruiz, M. T. [Departamento de Astronomia, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Casilla 36-D (Chile); Jones, H. R. A.; Tuomi, M.; Barnes, J. R.; Pavlenko, Y. V.; Pinfield, D. J. [Center for Astrophysics, University of Hertfordshire, College Lane Campus, Hatfield, Hertfordshire, AL10 9AB (United Kingdom); Murgas, F. [Instituto de Astrofisica de Canarias, Via Lactea, E-38205 La Laguna, Tenerife (Spain); Ivanyuk, O. [Main Astronomical Observatory of National Academy of Sciences of Ukraine, 27 Zabolotnoho, Kyiv 127, 03680 (Ukraine); Jordan, A., E-mail: jjenkins@das.uchile.cl [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, 7820436 Macul, Santiago (Chile) 2013-04-01 We announce the discovery of a low-mass planet orbiting the super metal-rich K0V star HD 77338 as part of our ongoing Calan-Hertfordshire Extrasolar Planet Search. The best-fit planet solution has an orbital period of 5.7361 {+-} 0.0015 days and with a radial velocity semi-amplitude of only 5.96 {+-} 1.74 ms{sup -1}, we find a minimum mass of 15.9{sup +4.7}{sub -5.3} M{sub Circled-Plus }. The best-fit eccentricity from this solution is 0.09{sup +0.25}{sub -0.09}, and we find agreement for this data set using a Bayesian analysis and a periodogram analysis. We measure a metallicity for the star of +0.35 {+-} 0.06 dex, whereas another recent work finds +0.47 {+-} 0.05 dex. Thus HD 77338b is one of the most metal-rich planet-host stars known and the most metal-rich star hosting a sub-Neptune-mass planet. We searched for a transit signature of HD 77338b but none was detected. We also highlight an emerging trend where metallicity and mass seem to correlate at very low masses, a discovery that would be in agreement with the core accretion model of planet formation. The trend appears to show that for Neptune-mass planets and below, higher masses are preferred when the host star is more metal-rich. Also a lower boundary is apparent in the super metal-rich regime where there are no very low mass planets yet discovered in comparison to the sub-solar metallicity regime. A Monte Carlo analysis shows that this low-mass planet desert is statistically significant with the current sample of 36 planets at the {approx}4.5{sigma} level. In addition, results from Kepler strengthen the claim for this paucity of the lowest-mass planets in super metal-rich systems. Finally, this discovery adds to the growing population of low-mass planets around low-mass and metal-rich stars and shows that very low mass planets can now be discovered with a relatively small number of data points using stable instrumentation. 11. Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon. III. HD 50138 Science.gov (United States) Jeřábková, T.; Korčáková, D.; Miroshnichenko, A.; Danford, S.; Zharikov, S. V.; Kříček, R.; Zasche, P.; Votruba, V.; Šlechta, M.; Škoda, P.; Janík, J. 2016-02-01 Context. B[e] stars are anomalous objects around which extended circumstellar matter is present. The observed properties of the central star are significantly affected by the surrounding material. Therefore, the use of standard synthetic spectra is disputable in this case and our capability to study these objects is limited. One of the possibilities is to analyse variations of the spectral features. Long-term spectroscopic observations are required for this, but are not found in the literature. For our study we choose the B[e] star HD 50138 of the FS CMa type because of the indication that this star is a post-main-sequence star, although still not highly evolved. Therefore, it can be a good object for testing evolutionary models. Currently, HD 50138 is the most extensively observed FS CMa star which makes it an ideal object for modelling. Our observations fill the gap in the available data. Aims: To describe the variability of HD 50138 we have monitored this star spectroscopically over the last twenty years. To search for the periodicity on short-term scales, series of night-to-night observations were also obtained. We were able to obtain 130 spectra from four different telescopes - 1.06 m at Ritter Observatory (échelle, R ~ 26 000, 32 spectra, 1994-2003), the Perek 2 m telescope at Ondřejov Observatory (slit, R ~ 12 500, 56 spectra, 2004-2013), the 2.12 m telescope at Observatorio Astronomico Nacional San Pedro Martir (échelle, R ~ 18 000, 16 spectra, 2005-2013), and the 0.81 m telescope at Three College Observatory (échelle, R ~ 12 000, 26 spectra, 2013-2014). Methods: We describe and analyse variations of the chosen lines. The measurements of the equivalent widths and radial velocities of the Hα, Hβ, and [O i] λλ 6300, 6364 Å lines are presented. The set of obtained spectra allows us to describe the changes on timescales from days to years. Results: The long-term quasi-periodic trend was found in the variations of the Hα equivalent width and confirmed 12. HD 100453: A Link Between Gas-Rich Protoplanetary Disks and Gas-Poor Debris Disks CERN Document Server Collins, K A; Hamaguchi, K; Wisniewski, J P; Brittain, S; Sitko, M; Carpenter, W J; Williams, J P; Mathews, G S; Williger, G M; Van Boekel, R; Carmona, A; Henning, T; Ancker, M E van den; Meeus, G; Chen, X P; Petre, R; Woodgate, B E 2009-01-01 HD 100453 has an IR spectral energy distribution (SED) which can be fit with a power-law plus a blackbody. Previous analysis of the SED suggests that the system is a young Herbig Ae star with a gas-rich, flared disk. We reexamine the evolutionary state of the HD 100453 system by refining its age (based on a candidate low-mass companion) and by examining limits on the disk extent, mass accretion rate, and gas content of the disk environment. We confirm that HD 100453B is a common proper motion companion to HD 100453A, with a spectral type of M4.0V - M4.5V, and derive an age of 10 +/- 2 Myr. We find no evidence of mass accretion onto the star. Chandra ACIS-S imagery shows that the Herbig Ae star has L_X/L_Bol and an X-ray spectrum similar to non-accreting Beta Pic Moving Group early F stars. Moreover, the disk lacks the conspicuous Fe II emission and excess FUV continuum seen in spectra of actively accreting Herbig Ae stars, and from the FUV continuum, we find the accretion rate is < 1.4x10^-9 M_Sun yr^-1. A... 13. Discovery of multiple pulsations in the new δ Scuti star HD 92277: Asteroseismology from Dome A, Antarctica Energy Technology Data Exchange (ETDEWEB) Zong, Weikai; Fu, Jian-Ning; Niu, Jia-Shu; Zhu, Zonghong [Department of Astronomy, Beijing Normal University, Beijing 100875 (China); Charpinet, S.; Vauclair, G. [Université de Toulouse, UPS-OMP, IRAP, F-31400 Toulouse (France); Ashley, Michael C. B.; Lawrence, Jon S.; Luong-Van, Daniel [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Cui, Xiangqun; Gong, Xuefei [Nanjing Institute of Astronomical Optics and Technology, Nanjing 210042 (China); Feng, Longlong; Wang, Lifan; Yuan, Xiangyan; Zhu, Zhenxi [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Liu, Qiang; Wang, Lingzhi; Zhou, Xu [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Pennypacker, Carl R. [Center for Astrophysics, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); York, Donald G., E-mail: jnfu@bnu.edu.cn [Department of Astronomy and Astrophysics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States) 2015-02-01 We report the discovery of low-amplitude oscillations in the star HD 92277 from long, continuous observations in the r and g bands using the CSTAR telescopes in Antarctica. A total of more than 1950 hours of high-quality light curves were used to categorize HD 92277 as a new member of the δ Scuti class. We have detected 21 (20 frequencies are independent and one is the linear combination) and 14 (13 frequencies are independent and one is the linear combination) pulsation frequencies in the r and g bands, respectively, indicating a multi-periodic pulsation behavior. The primary frequency f{sub 1} = 10.810 days{sup −1} corresponds to a period of 0.0925 days and is an l = 1 mode. We estimate a B − V index of 0.39 and derive an effective temperature of 6800 K for HD 92277. We conclude that long, continuous and uninterrupted time-series photometry can be performed from Dome A, Antarctica, and that this is especially valuable for asteroseismology where multi-color observations (often not available from space-based telescopes) assist with mode identification. 14. Abundance analysis, spectral variability, and search for the presence of a magnetic field in the typical PGa star HD19400 CERN Document Server Hubrig, S; Gonzalez, J F; Carroll, T A; Ilyin, I; Schöller, M; Drake, N A; Korhonen, H; Briquet, M 2014-01-01 The aim of this study is to carry out an abundance determination, to search for spectral variability and for the presence of a weak magnetic field in the typical PGa star HD19400. High-resolution, high signal-to-noise HARPS spectropolarimetric observations of HD19400 were obtained at three different epochs in 2011 and 2013. For the first time, we present abundances of various elements determined using an ATLAS12 model, including the abundances of a number of elements not analysed by previous studies, such as Ne I, Ga II, and Xe II. Several lines of As II are also present in the spectra of HD19400. To study the variability, we compared the behaviour of the line profiles of various elements. We report on the first detection of anomalous shapes of line profiles belonging to Mn and Hg, and the variability of the line profiles belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the variability of the line profiles of these elements is caused by their non-uniform surface distribution, similar to the pr... 15. The California Planet Survey IV: A Planet Orbiting the Giant Star HD 145934 and Updates to Seven Systems with Long-Period Planets OpenAIRE Feng, Y. Katherina; Wright, Jason T.; Nelson, Benjamin; Wang, Sharon X.; Ford, Eric B.; Marcy, Geoffrey W.; Isaacson, Howard; Howard, Andrew W. 2015-01-01 We present an update to seven stars with long-period planets or planetary candidates using new and archival radial velocities from Keck-HIRES and literature velocities from other telescopes. Our updated analysis better constrains orbital parameters for these planets, four of which are known multi-planet systems. HD 24040 b and HD 183263 c are super-Jupiters with circular orbits and periods longer than 8 yr. We present a previously unseen linear trend in the residuals of HD 66428 indicative on... 16. On the interplay between flaring and shadowing in disks around Herbig Ae/Be stars CERN Document Server Acke, B; Ancker, M van den; Bouwman, J; Ochsendorf, B; Juhasz, A; Waters, R 2009-01-01 Based on the SED, Herbig stars have been categorized into two observational groups, reflecting their overall disk structure: group I members have disks with a higher degree of flaring than their group II counterparts. We investigate the 5-35 um Spitzer IRS spectra of a sample of 13 group I sources and 20 group II sources. We focus on the continuum emission to study the underlying disk geometry. We have determined the [30/13.5] and [13.5/7] continuum flux ratios. The 7-um flux excess with respect to the stellar photosphere is measured, as a marker for the strength of the near-IR emission produced by the inner disk. We have compared our data to self-consistent passive-disk model spectra, for which the same quantities were derived. We confirm the literature result that the difference in continuum emission between group I and II sources can largely be explained by a different amount of small dust grains. However, we report a strong correlation between the [30/13.5] and [13.5/7] flux ratios for Meeus group II sour... 17. Precise radial velocities of giant stars IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a ~13.6 au eccentric binary system CERN Document Server Ortiz, Mauricio; Trifonov, Trifon; Quirrenbach, Andreas; Mitchell, David; Nowak, Grzegorz; Buenzli, Esther; Zimmerman, Neil; Bonnefoy, Mickael; Skemer, Andy; Defrère, Denis; Lee, Man Hoi; Fischer, Debra; Hinz, Philip 2016-01-01 Context: For over 12 years, we have carried out a precise radial velocity survey of a sample of 373 G and K giant stars using the Hamilton \\'Echelle Spectrograph at Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims: We aim at detecting and characterizing substellar+stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods: We obtained high precision radial velocity (RV) measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. In order to discriminate between RV variations due to non-radial pulsation or stellar spots we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to further characterize the system, we obtain high-resolution images with LMIRCam at the Large Binocular Telescope. Results: We report the likely discovery of a giant plane... 18. The Lick-Carnegie Exoplanet Survey: HD32963 -- A New Jupiter Analog Orbiting a Sun-like Star CERN Document Server Rowan, Dominick; Laughlin, Gregory; Vogt, Steven S; Butler, R Paul; Burt, Jennifer; Wang, Songhu; Holden, Brad; Hanson, Russell; Arriagada, Pamela; Keiser, Sandy; Teske, Johanna; Diaz, Matias 2015-01-01 We present a set of 109 new, high-precision Keck/HIRES radial velocity (RV) observations for the solar-type star HD 32963. Our dataset reveals a candidate planetary signal with a period of 6.49$\\pm$0.07 years and a corresponding minimum mass of 0.7$\\pm$0.03 Jupiter masses. Given Jupiter's crucial role in shaping the evolution of the early Solar System, we emphasize the importance of long-term radial velocity surveys. Finally, using our complete set of Keck radial velocities and correcting for the relative detectability of synthetic planetary candidates orbiting each of the 1,122 stars in our sample, we estimate the frequency of Jupiter analogs across our survey at approximately 3%. 19. The Role of Turbulent Pressure as a Coherent Pulsational Driving Mechanism: The Case of the δ Scuti Star HD 187547 DEFF Research Database (Denmark) Antoci, V.; Cunha, M.; Houdek, G.; 2014-01-01 HD 187547 was the first candidate that led to the suggestion that solar-like oscillations are present in δ Scuti stars. Longer observations, however, show that the modes interpreted as solar-like oscillations have either very long mode lifetimes, longer than 960 days, or are coherent. These results...... are incompatible with the nature of "pure" stochastic excitation as observed in solar-like stars. Nonetheless, one point is certain: the opacity mechanism alone cannot explain the oscillation spectrum of HD 187547. Here we present new theoretical investigations showing that convection dynamics can intrinsically...... excite coherent pulsations in the chemically peculiar δ Scuti star HD 187547. More precisely, it is the perturbations of the mean Reynold stresses (turbulent pressure) that drives the pulsations and the excitation takes place predominantly in the hydrogen ionization zone.... 20. Abundance analysis, spectral variability, and search for the presence of a magnetic field in the typical PGa star HD 19400 Science.gov (United States) Hubrig, S.; Castelli, F.; González, J. F.; Carroll, T. A.; Ilyin, I.; Schöller, M.; Drake, N. A.; Korhonen, H.; Briquet, M. 2014-08-01 The aim of this study is to carry out an abundance determination, to search for spectral variability and for the presence of a weak magnetic field in the typical PGa star HD 19400. High-resolution, high signal-to-noise High Accuracy Radial-velocity Planet Searcher (HARPS) spectropolarimetric observations of HD 19400 were obtained at three different epochs in 2011 and 2013. For the first time, we present abundances of various elements determined using an ATLAS12 model, including the abundances of a number of elements not analysed by previous studies, such as Ne I, Ga II, and Xe II. Several lines of As II are also present in the spectra of HD 19400. To study the variability, we compared the behaviour of the line profiles of various elements. We report on the first detection of anomalous shapes of line profiles belonging to Mn and Hg, and the variability of the line profiles belonging to the elements Hg, P, Mn, Fe, and Ga. We suggest that the variability of the line profiles of these elements is caused by their non-uniform surface distribution, similar to the presence of chemical spots detected in HgMn stars. The search for the presence of a magnetic field was carried out using the moment technique and the Singular Value Decomposition (SVD) method. Our measurements of the magnetic field with the moment technique using 22 Mn II lines indicate the potential existence of a weak variable longitudinal magnetic field on the first epoch. The SVD method applied to the Mn II lines indicates = -76 ± 25 G on the first epoch, and at the same epoch the SVD analysis of the observations using the Fe II lines shows = -91 ± 35 G. The calculated false alarm probability values, 0.008 and 0.003, respectively, are above the value 10-3, indicating no detection. 1. Stellar Parameters for HD 69830, a Nearby Star with Three Neptune Mass Planets and an Asteroid Belt CERN Document Server Tanner, Angelle; von Braun, Kaspar; Kane, Stephen; Brewer, John M; Farrington, Chris; van Belle, Gerard T; Beichman, Charles A; Fischer, Debra; Brummelaar, Theo A ten; McAlister, Harold A; Schaefer, Gail 2014-01-01 We used the CHARA Array to directly measure the angular diameter of HD 69830, home to three Neptune mass planets and an asteroid belt. Our measurement of 0.674+/-0.014 milli-arcseconds for the limb-darkened angular diameter of this star leads to a physical radius of R$_*$= 0.9058$\\pm$0.0190 R\\sun and luminosity of L* = 0.622+/-0.014 Lsun when combined with a fit to the spectral energy distribution of the star. Placing these observed values on an Hertzsprung-Russel (HR) diagram along with stellar evolution isochrones produces an age of 10.6+/-4 Gyr and mass of 0.863$\\pm$0.043 M\\sun. We use archival optical echelle spectra of HD 69830 along with an iterative spectral fitting technique to measure the iron abundance ([Fe/H]=-0.04+/-0.03), effective temperature (5385+/-44 K) and surface gravity (log g = 4.49+/-0.06). We use these new values for the temperature and luminosity to calculate a more precise age of 7.5+/-Gyr. Applying the values of stellar luminosity and radius to recent models on the optimistic locati... 2. KEPLER-21b: A 1.6 R{sub Earth} PLANET TRANSITING THE BRIGHT OSCILLATING F SUBGIANT STAR HD 179070 Energy Technology Data Exchange (ETDEWEB) Howell, Steve B. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Rowe, Jason F.; Bryson, Stephen T. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Quinn, Samuel N. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Marcy, Geoffrey W.; Isaacson, Howard [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Ciardi, David R. [NASA Exoplanet Science Institute/Caltech, Pasadena, CA 91125 (United States); Chaplin, William J.; Elsworth, Yvonne [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Metcalfe, Travis S. [High Altitude Observatory and Scientific Computing Division, National Center for Atmospheric Research, Boulder, CO 80307 (United States); Monteiro, Mario J. P. F. G. [Centro de Astrofisica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Appourchaux, Thierry [Institut d' Astrophysique Spatiale, Universite Paris XI-CNRS (UMR8617), Batiment 121, 91405 Orsay Cedex (France); Basu, Sarbani [Department of Astronomy, Yale University, New Haven, CT 06520-8101 (United States); Creevey, Orlagh L. [Departamento de Astrofisica, Universidad de La Laguna, E-38206 La Laguna, Tenerife (Spain); Gilliland, Ronald L. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Quirion, Pierre-Olivier [Canadian Space Agency, 6767 Boulevard de l' Aeroport, Saint-Hubert, QC, J3Y 8Y9 (Canada); Stello, Denis [Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006 (Australia); Kjeldsen, Hans; Christensen-Dalsgaard, Joergen [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Garcia, Rafael A. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot-IRFU/SAp, 91191 Gif-sur-Yvette Cedex (France); and others 2012-02-20 We present Kepler observations of the bright (V = 8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R{sub Earth} object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34 {+-} 0.06 M{sub Sun} and 1.86 {+-} 0.04 R{sub Sun }, respectively, as well as yielding an age of 2.84 {+-} 0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3{sigma}) that the transit event is caused by a 1.64 {+-} 0.04 R{sub Earth} exoplanet in a 2.785755 {+-} 0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of {approx}10 M{sub Earth} (2{sigma}). HD 179070 is the brightest exoplanet host star yet discovered by Kepler. 3. Multiplicity among chemically peculiar stars II. Cool magnetic Ap stars OpenAIRE Carrier, F.; North, P.; Udry, S.; Babel, J. 2002-01-01 We present new orbits for sixteen Ap spectroscopic binaries, four of which might in fact be Am stars, and give their orbital elements. Four of them are SB2 systems: HD 5550, HD 22128, HD 56495 and HD 98088. The twelve other stars are : HD 9996, HD 12288, HD 40711, HD 54908, HD 65339, HD 73709, HD 105680, HD 138426, HD 184471, HD 188854, HD 200405 and HD 216533. Rough estimates of the individual masses of the components of HD 65339 (53 Cam) are given, combining our radial velocities with the r... 4. HD 85567: A Herbig B[e] star or an interacting B[e] binary CERN Document Server Wheelwright, H E; Garatti, A Caratti o; Lopez, R Garcia 2013-01-01 Context. HD 85567 is an enigmatic object exhibiting the B[e] phenomenon, i.e. an infrared excess and forbidden emission lines in the optical. The object's evolutionary status is uncertain and there are conflicting claims that it is either a young stellar object or an evolved, interacting binary. Aims. To elucidate the reason for the B[e] behaviour of HD 85567, we have observed it with the VLTI and AMBER. Methods. Our observations were conducted in the K-band with moderate spectral resolution (R~1500, i.e. 200 km/s). The spectrum of HD 85567 exhibits Br gamma and CO overtone bandhead emission. The interferometric data obtained consist of spectrally dispersed visibilities, closure phases and differential phases across these spectral features and the K-band continuum. Results. The closure phase observations do not reveal evidence of asymmetry. The apparent size of HD 85567 in the K-band was determined by fitting the visibilities with a ring model. The best fitting radius, 0.8 +/- 0.3 AU, is relatively small maki... 5. Spectroscopy of the post-AGB star HD 101584 (IRAS 11385-5517) NARCIS (Netherlands) Sivarani, T; Parthasarathy, M; Garcia-Lario, P; Manchado, A; Pottasch, [No Value 1999-01-01 From an analysis of the spectrum (4000 Angstrom to 8800 Angstrom) of HD 101584 it is found that most of the neutral and single ionized metallic lines are in emission. The forbidden emission lines of [OI] 6300 Angstrom and 6363 Angstrom and [CI] 8727 Angstrom are detected, which indicate the presence 6. Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682 NARCIS (Netherlands) J.H. Grunhut; G.A. Wade; J.O. Sundqvist; A. ud-Doula; C. Neiner; R. Ignace; W.L.F. Marcolino; T. Rivinius; A. Fullerton; L. Kaper; B. Mauclaire; C. Buil; T. Garrel; J. Ribeiro; S. Ubaud 2012-01-01 The O9IV star HD 57682, discovered to be magnetic within the context of the Magnetism in Massive Stars (MiMeS) survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, t 7. Planetary Companions to Evolved Intermediate-Mass Stars: 14 Andromedae, 81 Ceti, 6 Lyncis, and HD 167042 CERN Document Server Sato, Bun'ei; Omiya, Masashi; Izumiura, Hideyuki; Kambe, Eiji; Masuda, Seiji; Takeda, Yoichi; Itoh, Yoichi; Ando, Hiroyasu; Yoshida, Michitoshi; Kokubo, Eiichiro; Ida, Shigeru 2008-01-01 We report on the detection of four extrasolar planets orbiting evolved intermediate-mass stars from a precise Doppler survey of G and K giants at Okayama Astrophysical Observatory. All of the host stars are considered to be formerly early F-type or A-type dwarfs when they were on the main sequence. 14 And (K0 III) is a clump giant with a mass of 2.2 M_solar and has a planet of minimum mass m_2sin i=4.8 M_Jup in a nearly circular orbit with a 186 day period. This is one of the innermost planets around evolved intermediate-mass stars and such planets have only been discovered in clump giants. 81 Cet (G5 III) is a clump giant with 2.4 M_solar hosting a planet of m_2sin i=5.3 M_Jup in a 953 day orbit with an eccentricity of e=0.21. 6 Lyn (K0 IV) is a less evolved subgiant with 1.7 M_solar and has a planet of m_2sin i=2.4 M_Jup in a 899 day orbit with e=0.13. HD 167042 (K1 IV) is also a less evolved star with 1.5 M_solar hosting a planet of m_2sin i=1.6 M_Jup in a 418 day orbit with e=0.10. This planet was indepen... 8. B fields in OB stars (BOB): Detection of a strong magnetic field in the O9.7 V star HD54879 CERN Document Server Castro, N; Hubrig, S; Simón-Díaz, S; Schöller, M; Ilyin, I; Carrol, T A; Langer, N; Morel, T; Schneider, F R N; Przybilla, N; Herrero, A; de Koter, A; Oskinova, L M; Reisenegger, A; Sana, H 2015-01-01 The number of magnetic stars detected among massive stars is small; nevertheless, the role played by the magnetic field in stellar evolution cannot be disregarded. Links between line profile variability, enhancements/depletions of surface chemical abundances, and magnetic fields have been identified for low-mass B-stars, but for the O-type domain this is almost unexplored. Based on FORS2 and HARPS spectropolarimetric data, we present the first detection of a magnetic field in HD54879, a single slowly rotating O9.7 V star. Using two independent and different techniques we obtained the firm detection of a surface average longitudinal magnetic field with a maximum amplitude of about 600 G, in modulus. A quantitative spectroscopic analysis of the star with the stellar atmosphere code FASTWIND results in an effective temperature and a surface gravity of 33000$\\pm1000$K and 4.0$\\pm0.1$dex. The abundances of carbon, nitrogen, oxygen, silicon, and magnesium are found to be slightly lower than solar, but compatible ... 9. Chemical analysis of 24 dusty (pre-)main-sequence stars CERN Document Server Acke, B; Acke, Bram; Waelkens, Christoffel 2004-01-01 We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and Vega-type stars in search for the lambda Bootis phenomenon. We present the results of the elemental abundances of the sample stars. Some of the stars were never before studied spectroscopically at optical wavelengths. We have determined the projected rotational velocities of our sample stars. Furthermore, we discuss stars that depict a (selective) depletion pattern in detail. HD 4881 and HD 139614 seem to display an overall deficiency. AB Aur and possibly HD 126367 have subsolar values for the iron abundance, but are almost solar in silicon. HD 100546 is the only clear lambda Bootis star in our sample. 10. Benchmark stars for Gaia: fundamental properties of the Population II star HD140283 from interferometric, spectroscopic and photometric data CERN Document Server Creevey, O; Berio, P; Heiter, U; von Braun, K; Mourard, D; Bigot, L; Boyajian, T S; Kervella, P; Morel, P; Pichon, B; Chiavassa, A; Nardetto, N; Perraut, K; Meilland, A; Alister, H A Mc; Brummelaar, T A ten; Sturmann, C Farrington J; Sturmann, L; Turner, N 2014-01-01 [..abridged.] We determined the fundamental properties of HD 140283 by obtaining new interferometric and spectroscopic measurements and combining them with photometry from the literature. The interferometric measurements were obtained using the visible interferometer VEGA on the CHARA array and we determined a 1D limb-darkened angular diameter of 0.353 +/- 0.013 milliarcseconds. Using photometry from the literature we derived the bolometric flux with two solutions: a zero-reddening one of Fbol = 3.890 +/- 0.066 1E-8 erg/s/cm2 and a solution with a maximum of Av = 0.1 mag, Fbol= 4.220 +/- 0.067 1E-8 erg/s/cm2. The interferometric Teff is thus 5534 +/- 103 K or 5647 +/- 105 K and its radius is R = 2.21 +/- 0.08 Rsol. Spectroscopic measurements of HD140283 were obtained using HARPS, NARVAL, and UVES and a 1D LTE analysis of H-alpha line wings yields Teff(Halpha) = 5626 +/- 75 K. Using fine-tuned stellar models including diffusion of elements we then determined the mass M and age t of HD140283. Once the metallici... 11. High-Resolution Spectroscopy of the Metal-Poor Star HD 187216 Science.gov (United States) Barzdis, A.; Začs, L.; Galazutdinov, G. Abundance analysis of the metal-poor, carbon-rich giant HD 187216 using high-resolution (R ≈ 45 000) spectrum was performed. An LTE abundance analysis was done for carefully selected clean atomic lines, using the Uppsala atmospheric model with Teff = 4000 K, log g = 0.75, ξt = 2.8 km s-1 and [Z] = --2.0. The mean metallicity [Fe/H] = --1.7 derived by using singly ionized iron lines is much higher than previously believed. It seems likely that Fe I lines, like many other neutral atomic lines, suffer from non-LTE effects that are significant at low metallicity and gravity. The abundances of the neutron capture elements are found to be enhanced by about 1.3 dex relative to the iron group elements. Possible causes of chemical peculiarities of HD 187216 are discussed. 12. The circumstellar shell of the post-AGB star HD 56126 the$^{12}CN\\/^{13}CN$isotope ratio and fractionation CERN Document Server Bakker, E J; Bakker, Eric J.; Lambert, David L. 1997-01-01 We have detected circumstellar absorption lines of the$^{12}$CN and$^{13}$CN Violet and Red System in the spectrum of the post-AGB star HD~56126. From a synthetic spectrum analysis, we derive a Doppler broadening parameter of$b=0.51\\pm0.04$km~s$^{-1}$,$^{12}$CN/$^{13}$CN$=38\\pm2$, and a lower limit of$2000$on$^{12}$CN/$^{14}$CN and$^{12}$C$^{14}$N/$^{12}$C$^{15}$N. A simple chemical model has been computed of the circumstellar shell surrounding HD~56126 that takes into account the gas-phase ion-molecule reaction between CN and C$^{+}$. From this we infer that this reaction leads to isotopic fractionation of CN. Taking into account the isotopic exchange reaction and the observed$^{12}$CN/$^{13}$CN we find$^{12}$C/$^{13}$C$\\sim 67$(for$T_{\\rm kin}=25$K). Our analysis suggests that$^{12}$CN has a somewhat higher rotational temperature than$^{13}$CN:$T_{\\rm rot}=11.5\\pm0.6$and$8.0\\pm0.6$K respectively. We identify possible causes for this difference in excitation temperature, among which the$...
13. Thorium-rich halo star HD221170: further evidence against the universality of the r-process
CERN Document Server
Yushchenko, A V; Goriely, S; Musaev, F; Shavrina, A; Kim, C; Kang, Y W; Kuznetsova, J; Yushchenko, V; Yushchenko, Alexander; Gopka, Vera; Goriely, Stephane; Musaev, Faig; Shavrina, Angelina; Kim, Chulhee; Kang, Young Woon; Kuznietsova, Juliana; Yushchenko, Vladimir
2004-01-01
We report the abundance determination in the atmosphere of the bright halo star HD221170. The spectra were taken with the Terskol Observatory's 2.0-m telescope with a resolution R=45000 and signal-to-noise ratio up to 250 in the wavelength region 3638-10275 \\AA. The adopted atmospheric parameters correspond to an effective temperature \\Tef=4475 K, a surface gravity \\lgg=1.0, a microturbulent velocity \\vmi=1.7 \\kms, and a macroturbulent velocity \\vma=4 \\kms. The abundances of 43 chemical elements were determined with the method of spectrum synthesis. The large overabundances (by 1 dex relative to iron) of elements with Z$>38$ are shown to follow the same pattern as the solar r-abundances. The present HD221170 analysis confirms the non-universality of the r-process, or more exactly the observation that the astrophysical sites hosting the r-process do not always lead to a unique relative abundance distribution for the bulk Ba to Hg elements, the Pb-peak elements, and the actinides.
14. Know the Star, Know the Planet. V. Characterization of the Stellar Companion to the Exoplanet Host HD 177830
CERN Document Server
Roberts, Lewis C; Crepp, Justin R; Baranec, Christoph; Beichman, Charles; Brenner, Douglas; Burruss, Rick; Cady, Eric; Luszcz-Cook, Statia; Dekany, Richard; Hillenbrand, Lynne; Hinkley, Sasha; King, David; Lockhart, Thomas G; Nilsson, Ricky; Parry, Ian R; Pueyo, Laurent; Sivaramakrishnan, Anand; Soummer, Remi; Rice, Emily L; Veicht, Aaron; Vasisht, Gautam; Zhai, Chengxing; Zimmerman, Neil T
2015-01-01
HD 177830 is an evolved K0IV star with two known exoplanets. In addition to the planetary companions it has a late-type stellar companion discovered with adaptive optics imagery. We observed the binary star system with the PHARO near-IR camera and the Project 1640 coronagraph. Using the Project 1640 coronagraph and integral field spectrograph we extracted a spectrum of the stellar companion. This allowed us to determine that the spectral type of the stellar companion is a M4$\\pm$1V. We used both instruments to measure the astrometry of the binary system. Combining these data with published data, we determined that the binary star has a likely period of approximately 800 years with a semi-major axis of 100-200 AU. This implies that the stellar companion has had little or no impact on the dynamics of the exoplanets. The astrometry of the system should continue to be monitored, but due to the slow nature of the system, observations can be made once every 5-10 years.
15. The CoRoT target HD 175726: an active star with weak solar-like oscillations
Science.gov (United States)
Mosser, B.; Michel, E.; Appourchaux, T.; Barban, C.; Baudin, F.; Boumier, P.; Bruntt, H.; Catala, C.; Deheuvels, S.; García, R. A.; Gaulme, P.; Regulo, C.; Roxburgh, I.; Samadi, R.; Verner, G.; Auvergne, M.; Baglin, A.; Ballot, J.; Benomar, O.; Mathur, S.
2009-10-01
Context: The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for 27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio. Aims: Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum. Methods: The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato. Results: The mean large separation has been measured to be 97.2±0.5 μHz, slightly below the expected value determined from solar scaling laws. We also show strong evidence for variation of the large separation with frequency. The bolometric mode amplitude is only 1.7±0.25 ppm for radial modes, which is 1.7 times less than expected. Due to the low signal-to-noise ratio, mode identification is not possible for the available data set of HD 175726. The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESAs RSSD, Austria, Belgium, Brazil, Germany and Spain.
16. REVEALING THE ASYMMETRY OF THE WIND OF THE VARIABLE WOLF-RAYET STAR WR1 (HD 4004) THROUGH SPECTROPOLARIZATION
International Nuclear Information System (INIS)
In this paper, high quality spectropolarimetric observations of the Wolf-Rayet (WR) star WR1 (HD 4004) obtained with ESPaDOnS at the Canada-France-Hawaii Telescope are presented. All major emission lines present in the spectrum show depolarization in the relative Stokes parameters Q/I and U/I. From the behavior of the amount of line depolarization as a function of line strength, the intrinsic continuum light polarization of WR1 is estimated to be P/I = 0.443% ± 0.028% with an angle of θ = –26.°2. Although such a level of polarization could in principle be caused by a wind flattened by fast rotation, the scenario in which it is a consequence of the presence of corotating interaction regions (CIRs) in the wind is preferred. This is supported by previous photometric and spectroscopic observations showing periodic variations with a period of 16.9 days. This is now the third WR star thought to exhibit CIRs in its wind that is found to have line depolarization. Previous authors have found a strong correlation between line depolarization and the presence of an ejected nebula, which they interpret as a sign that the star has relatively recently reached the WR phase since the nebula are thought to dissipate very fast. In cases where the presence of CIRs in the wind is favored to explain the depolarization across spectral lines, the above-mentioned correlation may indicate that those massive stars have only very recently transited from the previous evolutionary phase to the WR phase
17. VizieR Online Data Catalog: Abundances of metal-poor star HD 94028 (Roederer+, 2016)
Science.gov (United States)
Roederer, I. U.; Karakas, A. I.; Pignatari, M.; Herwig, F.
2016-06-01
We use two NUV spectroscopic data sets of HD 94028 available in the Mikulski Archive for Space Telescopes. These observations were made using STIS on board the HST. One spectrum (data sets O5CN01-03, GO-8197, PI. Duncan) has very high spectral resolution (R~110000). This spectrum covers ~1885-2147Å with signal-to-noise ratios (S/N)35/1 per pixel near 2140Å. The other spectrum (data sets O56D06-07, GO-7402, PI. Peterson) has high spectral resolution (R~30000). This spectrum covers 2280-3117Å with S/N ranging from ~20 near 2300Å to ~40 near 3100Å. Roederer et al. (2014, J/AJ/147/136) derived abundances from an optical spectrum of HD 94028 taken using the Robert G. Tull Coude Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, Texas. We rederive abundances from this spectrum. We also use an optical spectrum taken with the Ultraviolet and Visual Echelle Spectrograph (UVES) on the Very Large Telescope (VLT) Kueyen at Cerro Paranal, Chile. We obtained this spectrum from the ESO Science Archive. This spectrum covers 3050-3860Å at R~37000 with S/N ranging from ~40 near 3200Å to ~130 near 3800Å. (3 data files).
18. AE AURIGAE: FIRST DETECTION OF NON-THERMAL X-RAY EMISSION FROM A BOW SHOCK PRODUCED BY A RUNAWAY STAR
Energy Technology Data Exchange (ETDEWEB)
Lopez-Santiago, J.; Pereira, V.; De Castro, E. [Dpto. de Astrofisica y CC. de la Atmosfera, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Miceli, M.; Bonito, R. [Dipartimento di Fisica, Universita di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy); Del Valle, M. V.; Romero, G. E. [Instituto Argentino de Radioastronomia (IAR), CCT La Plata (CONICET), C.C.5, 1894 Villa Elisa, Buenos Aires (Argentina); Albacete-Colombo, J. F. [Centro Universitario Regional Zona Atlantica (CURZA), Universidad Nacional del COMAHUE, Monsenor Esandi y Ayacucho, 8500 Viedma, Rio Negro (Argentina); Damiani, F. [INAF-Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, I-90134 Palermo (Italy)
2012-09-20
Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to be detected in X-rays. To date, no stellar bow shock has been detected at such energies. We present the first detection of X-ray emission from a bow shock produced by a runaway star. The star is AE Aur, which was likely expelled from its birthplace due to the encounter of two massive binary systems and now is passing through the dense nebula IC 405. The X-ray emission from the bow shock is detected at 30'' northeast of the star, coinciding with an enhancement in the density of the nebula. From the analysis of the observed X-ray spectrum of the source and our theoretical emission model, we confirm that the X-ray emission is produced mainly by inverse Compton upscattering of infrared photons from dust in the shock front.
19. HD 164492C: a rapidly-rotating, H$\\alpha$-bright, magnetic early B star associated with a 12.5d spectroscopic binary
CERN Document Server
Wade, G A; Sikora, J; Bernier, M -É; Rivinius, Th; Alecian, E; Petit, V; Grunhut, J H
2016-01-01
We employ high resolution spectroscopy and spectropolarimetry to derive the physical properties and magnetic characteristics of the multiple system HD 164492C, located in the young open cluster M20. The spectrum reveals evidence of 3 components: a broad-lined early B star (HD 164492C1), a narrow-lined early B star (HD 164492C2), and a late B star (HD 164492C3). Components C2 and C3 exhibit significant ($>100$ km/s) bulk radial velocity variations with a period of $12.5351(7)$ d that we attribute to eccentric binary motion around a common centre-of-mass. Component C1 exhibits no detectable radial velocity variations. Using constraints derived from modeling the orbit of the C2+C3 binary and from synthesis of the combined spectrum, we determine the approximate physical characteristics of the components. We conclude that a coherent evolutionary solution consistent with the published age of M20 implies a distance to the system of $0.9\\pm 0.2$ kpc, corresponding to the smallest published values. We confirm the dete...
20. Spectroscopic study of the HgMn star HD 49606: the quest for binarity, abundance stratifications and magnetic field
Science.gov (United States)
Catanzaro, G.; Giarrusso, M.; Leone, F.; Munari, M.; Scalia, C.; Sparacello, E.; Scuderi, S.
2016-08-01
In this paper, we present a multi-instrument analysis of the mercury-manganese star HD 49606. New spectroscopic observations have been obtained by us with Catania Astrophysical Observatory Spectropolarimeter (CAOS@OAC) and High Accuracy Radial Velocity Planet Searcher-North@Telescopio Nazionale Galileo (HARPS-N@TNG). Combining these observations with archive data coming from other instruments, we performed a comprehensive analysis of this star. We highlight the motion around the centre of mass of a binary system of SB1 type, and we calculate the fundamental parameters characterizing its orbit. We also speculate on the nature of the unseen component. From the fit of H β and H γ, we determined the effective temperature and gravity, while from a number of metal lines, we derive the rotational and microturbulent velocities. Regarding chemical composition, we found underabundances of helium, oxygen, magnesium, sulfur and nickel, solar composition for carbon and overabundances for all the other elements. In particular, mercury abundance is derived taking into account an isotopic mixture different from the terrestrial one. As to magnesium, silicon and phosphorus, we found a non-constant abundance with the optical depth, a result currently considered an evidence of stratification. Spectropolarimetric observations have been performed in the attempt to highlight the presence of a magnetic field, but no detection has been found.
1. NIR Spectroscopy of the HAeBe Star HD 100546: III. Further Evidence of an Orbiting Companion?
CERN Document Server
Brittain, Sean D; Najita, Joan R; Quanz, Sascha P; Meyer, Michael R
2014-01-01
We report high resolution NIR spectroscopy of CO and OH emission from the Herbig Be star HD100546. We discuss how our results bear striking resemblance to several theoretically predicted signposts of giant planet formation. The properties of the CO and OH emission lines are consistent with our earlier interpretation that these diagnostics provide indirect evidence for a companion that orbits the star close to the disk wall (at ~13au). The asymmetry of the OH spectral line profiles and their lack of time variability are consistent with emission from gas in an eccentric orbit at the disk wall that is approximately stationary in the inertial frame. The time variable spectroastrometric properties of the CO v=1-0 emission line point to an orbiting source of CO emission with an emitting area similar to that expected for a circumplanetary disk (~0.1au^2) assuming the CO emission is optically thick. We also consider a counterhypothesis to this interpretation, namely that the variable CO emission arises from a bright ...
2. The CoRoT target HD175726: an active star with weak solar-like oscillations
CERN Document Server
Mosser, B; Appourchaux, T; Barban, C; Baudin, F; Boumier, P; Bruntt, H; Catala, C; Deheuvels, S; García, R A; Gaulme, P; Regulo, C; Roxburgh, I; Samadi, R; Verner, G; Auvergne, M; Baglin, A; Ballot, J; Benomar, O; Mathur, S
2009-01-01
Context. The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD175726 that lasted for 27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio. Aims. Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum. Methods. The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato. Results. The mean large separation has been measured to be 97.2+-0.5 microHz, slightly below the expected value determined from solar scaling laws.We also show stro...
3. ALMA observations of the molecular gas in the debris disk of the 30 Myr old star HD 21997
CERN Document Server
Kóspál, Á; Juhász, A; Ábrahám, P; Apai, D; Csengeri, T; Grady, C A; Henning, Th; Hughes, A M; Kiss, Cs; Pascucci, I; Schmalzl, M
2013-01-01
The 30 Myr old A3-type star HD 21997 is one of the two known debris dust disks having a measurable amount of cold molecular gas. With the goal of understanding the physical state, origin, and evolution of the gas in young debris disks, we obtained CO line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). Here we report on the detection of 12CO and 13CO in the J=2-1 and J=3-2 transitions and C18O in the J=2-1 line. The gas exhibits a Keplerian velocity curve, one of the few direct measurements of Keplerian rotation in young debris disks. The measured CO brightness distribution could be reproduced by a simple star+disk system, whose parameters are r_in < 26 AU, r_out = 138 +/- 20 AU, M_*=1.8 +0.5 -0.2 M_Sun, and i = 32.6 +/- 3.1 degrees. The total CO mass, as calculated from the optically thin C18O line, is about (4-8) x 10^-2 M_Earth, while the CO line ratios suggest a radiation temperature on the order of 6-9 K. Comparing our results with those obtained for the dust component of th...
4. Revealing the Asymmetry of the Wind of the Variable Wolf-Rayet Star WR1 (HD4004) Through Spectropolarization
CERN Document Server
St-Louis, Nicole
2013-01-01
In this paper, high quality spectropolarimetric observations of the Wolf-Rayet (WR) Star WR1 (HD4004) obtained with ESPaDOnS at CFHT are presented. All major emission lines present in the spectrum show depolarization in the relative Stokes parameters Q/I and U/I. From the behaviour of the amount of line depolarization as a function of line strength, the intrinsic continuum light polarization of WR1 is estimated to be P/I=0.443 \\pm 0.028 % with an angle of \\theta=-26.2^o. Although such a level of polarization could in principle be caused by a wind flattened by fast rotation, the scenario in which it is a consequence of the presence in the wind of Corotating Interaction Regions (CIRs) is preferred. This is supported by previous photometric and spectroscopic observations showing periodic variations with a period of 16.9 days. This is now the third WR star thought to exhibit CIRs in its wind that is found to have line depolarization. Previous authors have found a strong correlation between line depolarization and...
5. The surface magnetic field and chemical abundance distributions of the B2V helium-strong star HD184927
CERN Document Server
Yakunin, I; Bohlender, D; Kochukhov, O; Marcolino, W; Shultz, M; Monin, D; Grunhut, J; Sitnova, T; Tsymbal, V
2014-01-01
A new time series of high-resolution Stokes I and V spectra of the magnetic B2V star HD 184927 has been obtained in the context of the Magnetism in Massive Stars (MiMeS) Large Program with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope and dimaPol liquid crystal spectropolarimeter at 1.8-m telescope of Dominion Astrophysical Observatory. We model the optical and UV spectrum obtained from the IUE archive to infer the stellar physical parameters. Using magnetic field measurements we derive an improved rotational period of 9.53102+-0.0007d. We infer the longitudinal magnetic field from lines of H, He and various metals, revealing large differences between the apparent field strength variations determined from different elements. Magnetic Doppler Imaging using He and O lines yields strongly nonuniform surface distributions of these elements. We demonstrate that the diversity of longitudinal field variations can be understood as due to the combination of element-specific surface abundance di...
6. An interferometric-spectroscopic orbit for the binary HD 195987 Testing models of stellar evolution for metal-poor stars
CERN Document Server
Torres, G; Latham, D W; Pan, M; Stefanik, R P; Torres, Guillermo; Boden, Andrew F.; Latham, David W.; Pan, Margaret; Stefanik, Robert P.
2002-01-01
We report spectroscopic and interferometric observations of the moderately metal-poor double-lined binary system HD 195987, with an orbital period of 57.3 days. By combining our radial-velocity and visibility measurements we determine the orbital elements and derive absolute masses for the components of M(A) = 0.844 +/- 0.018 Msun and M(B) = 0.6650 +/- 0.0079 Msun, with relative errors of 2% and 1%, respectively. We also determine the orbital parallax, pi(orb) = 46.08 +/- 0.27 mas, corresponding to a distance of 21.70 +/- 0.13 pc. The parallax and the measured brightness difference between the stars in V, H, and K yield the component absolute magnitudes in those bands. We also estimate the effective temperatures of the stars as Teff(A) = 5200 +/- 100 K and Teff(B) = 4200 +/- 200 K. Together with detailed chemical abundance analyses from the literature giving [Fe/H] approximately -0.5 (corrected for binarity) and [alpha/Fe] = +0.36, we use these physical properties to test current models of stellar evolution f...
7. A Survey for a Coeval, Comoving Group Associated with HD 141569
CERN Document Server
Aarnio, Alicia N; Stassun, Keivan G; Mamajek, Eric E; James, David J
2008-01-01
We present results of a search for a young stellar moving group associated with the star HD 141569, a nearby, isolated Herbig AeBe primary member of a 5+/-3 Myr-old triple star system on the outskirts of the Sco-Cen complex. Our spectroscopic survey identified a population of 21 Li-rich, <30 Myr-old stars within 30 degrees of HD 141569 which possess similar proper motions with the star. The spatial distribution of these Li-rich stars, however, is not suggestive of a moving group associated with the HD 141569 triplet, but rather this sample appears cospatial with Upper Scorpius and Upper Centaurus Lupus. We apply a modified moving cluster parallax method to compare the kinematics of these youthful stars with Upper Scorpius and Upper Centaurus Lupus. Eight new potential members of Upper Scorpius and five new potential members of Upper Centaurus Lupus are identified. A substantial moving group with an identifiable nucleus within 15 degrees (~30 pc) of HD 141569 is not found in this sample. Evidently, the HD 1...
8. AE 941.
Science.gov (United States)
2004-01-01
AE 941 [Arthrovas, Neoretna, Psovascar] is shark cartilage extract that inhibits angiogenesis. AE 941 acts by blocking the two main pathways that contribute to the process of angiogenesis, matrix metalloproteases and the vascular endothelial growth factor signalling pathway. When initial development of AE 941 was being conducted, AEterna assigned the various indications different trademarks. Neovastat was used for oncology, Psovascar was used for dermatology, Neoretna was used for ophthalmology and Arthrovas was used for rheumatology. However, it is unclear if these trademarks will be used in the future and AEterna appears to only be using the Neovastat trademark in its current publications regardless of the indication. AEterna Laboratories signed commercialisation agreements with Grupo Ferrer Internacional SA of Spain and Medac GmbH of Germany in February 2001. Under the terms of the agreement, AEterna has granted exclusive commercialisation and distribution rights to AE 941 in oncology to Grupo Ferrer Internacional for the Southern European countries of France, Belgium, Spain, Greece, Portugal and Italy. It also has rights in Central and South America. Medac GmbH will have marketing rights in Germany, the UK, Scandinavia, Switzerland, Austria, Ireland, the Netherlands and Eastern Europe. In October 2002, AEterna Laboratories announced that it had signed an agreement with Australian healthcare products and services company Mayne Group for marketing AE 941 (as Neovastat) in Australia, New Zealand, Canada and Mexico. In March 2003, AEterna Laboratories announced it has signed an agreement with Korean based LG Life Sciences Ltd for marketing AE 941 (as Neovastat) in South Korea. The agreement provides AEterna with upfront and milestone payments, as well as a return on manufacturing and sales of AE 941. AEterna Laboratories had granted Alcon Laboratories an exclusive worldwide licence for AE 941 for ophthalmic products. However, this licence has been terminated. In
9. The origin of the excess transit absorption in the HD 189733 system: planet or star?
CERN Document Server
Barnes, J R; Staab, D; Anglada-Escudé, G
2016-01-01
We have detected excess absorption in the emission cores of Ca II H & K during transits of HD 189733b for the first time. Using observations of three transits we investigate the origin of the absorption, which is also seen in H{\\alpha} and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of {\\Delta}{\\lambda} = 0.4 & 0.6 $\\AA$ yields excess absorption of t$_d$ = 0.0074 $\\pm$ 0.0044 (1.7{\\sigma}; Transit 1) and 0.0214 +/- 0.0022 (9.8{\\sigma}; Transit 2). Similarly, we detect excess H{\\alpha} absorption in a passband of width {\\Delta}{\\lambda} = 0.7 $\\AA$, with t$_d$ = 0.0084 $\\pm$ 0.0016 (5.2{\\sigma}) and 0.0121 $\\pm$ 0.0012 (9.9{\\sigma}). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of t$_d$ = 0.0041 $\\pm$ 0.0006 (6.5{\\sigma}). By considering the time series observations of each line, we find that the excess apparent absorptio...
10. Conditions for HD Cooling in the First Galaxies Revisited: Interplay between Far-Ultraviolet and Cosmic Ray Feedback in Population III Star Formation
CERN Document Server
Nakauchi, Daisuke; Omukai, Kazuyuki
2014-01-01
HD dominates the cooling of primordial clouds with enhanced ionization, e.g. shock-heated clouds in structure formation or supernova remnants, relic HII regions of Pop III stars, and clouds with cosmic-ray (CR) irradiation. There, the temperature decreases to several 10 K and the characteristic stellar mass decreases to $\\sim 10\\ {\\rm M}_{\\odot}$, in contrast with first stars formed from undisturbed pristine clouds ($\\sim 100\\ {\\rm M}_{\\odot}$). However, without CR irradiation, even weak far ultra-violet (FUV) irradiation suppresses HD formation/cooling. Here, we examine conditions for HD cooling in primordial clouds including both FUV and CR feedback. At the beginning of collapse, the shock-compressed gas cools with its density increasing, while the relic HII region gas cools at a constant density. Moreover, shocks tend to occur in denser environments than HII regions. Owing to the higher column density and the more effective shielding, the critical FUV intensity for HD cooling in a shock-compressed gas beco...
11. Magnetic fields and differential rotation on the pre-main sequence I: The early-G star HD 141943 - brightness and magnetic topologies
CERN Document Server
Marsden, S C; Vélez, J C Ramírez; Alecian, E; Brown, C J; Carter, B D; Donati, J F; Dunstone, N; Hart, R; Semel, M; Waite, I A
2011-01-01
Spectroscopic and spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at four observing epochs (in 2006, 2007, 2009 and 2010). The observations were undertaken at the 3.9-m Anglo-Australian Telescope using the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. Brightness and surface magnetic field topologies were reconstructed for the star using the technique of least-squares deconvolution to increase the signal-to-noise of the data. The reconstructed brightness maps show that HD 141943 had a weak polar spot and a significant amount of low latitude features, with little change in the latitude distribution of the spots over the 4 years of observations. The surface magnetic field was reconstructed at three of the epochs from a high order (l <= 30) spherical harmonic expansion of the spectropolarimetric observations. The reconstructed magnetic topologies show that in 2007 and 2010 the surface magnetic field was reasonably balanced betwee...
12. The origin of the excess transit absorption in the HD 189733 system: planet or star?
Science.gov (United States)
Barnes, J. R.; Haswell, C. A.; Staab, D.; Anglada-Escudé, G.
2016-10-01
We have detected excess absorption in the emission cores of Ca II H&K during transits of HD 189733b for the first time. Using observations of three transits, we investigate the origin of the absorption, which is also seen in Hα and the Na I D lines. Applying differential spectrophotometry methods to the Ca II H and Ca II K lines combined, using respective passband widths of Δλ = 0.4 and 0.6 Å yields excess absorption of td = 0.0074 ± 0.0044 (1.7σ; Transit 1) and 0.0214 ± 0.0022 (9.8σ; Transit 2). Similarly, we detect excess Hα absorption in a passband of width Δλ = 0.7 Å, with td = 0.0084 ± 0.0016 (5.2σ) and 0.0121 ± 0.0012 (9.9σ). For both lines, Transit 2 is thus significantly deeper. Combining all three transits for the Na I D lines yields excess absorption of td = 0.0041 ± 0.0006 (6.5σ). By considering the time series observations of each line, we find that the excess apparent absorption is best recovered in the stellar reference frame. These findings lead us to postulate that the main contribution to the excess transit absorption in the differential light curves arises because the normalizing continuum bands form in the photosphere, whereas the line cores contain a chromospheric component. We cannot rule out that part of the excess absorption signature arises from the planetary atmosphere, but we present evidence which casts doubt on recent claims to have detected wind motions in the planet's atmosphere in these data.
13. The fundamental parameters of the roAp star HD 24712. A rapidly oscillator at the red edge of the instability strip
Science.gov (United States)
Perraut, K.; Brandão, I.; Cunha, M.; Shulyak, D.; Mourard, D.; Nardetto, N.; ten Brummelaar, T. A.
2016-05-01
Context. There is still a debate about the nature of the mechanism that causes the pulsation excitation of the rapidly oscillating Ap stars that oscillate above the highest theoretically acoustic frequency. HD 24712 is a good test case for such a study because it is bright, its parallax accurately determined, and its frequency spectrum is well known. Aims: Visible long-baseline interferometry is a unique technique for measuring accurate angular diameters of targets as small as the brightest roAp stars, and thus estimating accurate radii by a method as independent as possible of atmosphere models. Methods: We used the visible spectrograph VEGA at the CHARA long-baseline optical array to observe HD 24712, and we derived its limb-darkened diameter. We also estimated its bolometric flux from spectroscopic data in the literature and determined its radius, luminosity, and effective temperature. Results: We determined a limb-darkened angular diameter of 0.335 ± 0.009 mas for HD 24712 and derived a radius of R = 1.772 ± 0.057 R⊙, a luminosity of L = 7.2 ± 1.8 L⊙, and an effective temperature of Teff = 7235 ± 280 K, which is in very close agreement with the values provided by the self-consistent stratified model developed for this star. We used these fundamental parameters to set HD 24712 in the Hertzsprung-Russell diagram. Its position is marginally consistent with the region where high radial order modes are predicted to be excited by the κ-mechanism. Conclusions: We conclude that oscillations in this star are most likely not driven by the κ-mechanism. Based on observations made with the VEGA/CHARA spectro-interferometer.
14. Time-dependent spectral-feature variations of stars displaying the B[e] phenomenon III. HD 50138
CERN Document Server
Jeřábková, T; Miroshnichenko, A; Danford, S; Zharikov, S V; Kříček, R; Zasche, P; Votruba, V; Šlechta, M; Škoda, P; Janík, J
2015-01-01
We analyse spectroscopic observations of the B[e] star HD 50138 (MWC 158, V743 Mon, or IRAS 06491-0654), a member of the FS CMa group, obtained over the last twenty years. Four different epochs are identified in the observational data, where the variability of the spectral features is substantially different. Additionally, two long periods of (3 000 +/- 500) and (5 000 +/- 1000) days are found in the variations of the equivalent widths of the H alpha and [OI] 6300 A lines and radial velocities of the H alpha line violet peak. Modest signatures of a regular period of ~34 days in the radial velocities of the H alpha red peak and H beta central depression are found in the season 2013/2014. The H alpha V/R changes indicate a periodicity of ~50 days. The correlations between individual spectral features significantly restricts the model of the object and suggest that it is most likely a binary system with a highly distorted disc with spiral arms around the primary component. At the same time, no obvious signs of t...
15. X-ray emission from the double-binary OB-star system QZ Car (HD 93206)
CERN Document Server
Parkin, E R; Townsley, L K; Pittard, J M; Moffat, A F J; Naze, Y; Rauw, G; Oskinova, L M
2011-01-01
X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The orbit of systems A (O9.7 I+b2 v, PA = 21 d) and B (O8 III+o9 v, PB = 6 d) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three temperature thermal plasma model, characterised by cool, moderate, and hot plasma components at kT ~ 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of ~ 0.2 x 10^22 cm-2. Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of ~ 7 x 10^-13 erg s-1 cm-2, do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. ...
16. The Diverse Origins of Neutron-Capture Elements in the Metal-Poor Star HD 94028: Possible Detection of Products of i-process Nucleosynthesis
OpenAIRE
Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco; Herwig, Falk
2016-01-01
We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s-process; e.g., [Pb/Fe]=+0.79+/-0.32) and rapid neutron-capture process (r-process; e.g., [Eu/Fe]=+0.22+/-0.12), including unusually large molybdenum ([Mo/Fe]=+0.97+/-0.16) and ruthenium ([Ru/Fe]=+0.69+/-0.17) enhancements. ...
17. A HST study of the environment of the Herbig Ae/Be star LkHa 233 and its bipolar jet
CERN Document Server
Melnikov, Stanislav Yu; Eislöffel, Jochen; Bacciotti, Francesca; Locatelli, Ugo; Ray, Thomas P
2008-01-01
We present the results of HST/STIS and WFPC2 observations of LkHa 233 and its environment. LkHa233 is a Herbig Ae/Be star with a collimated bipolar jet. We investigate optical forbidden lines along the LkHa 233 jet to determine physical parameters of this jet (electron density n_e, hydrogen ionisation fraction x_e, electron temperature T_e, and mass density n_H). The knowledge of these parameters allows us a direct comparison of a jet from a Herbig star with those from T Tauri stars. The WFPC2 images in broad-band filters clearly show a dark lane caused either by a circumstellar disk or a dust torus. In the blueshifted lobe, n_e is close to or above the critical density for [SII] lines (2.5x10^4 cm^-3) in the first arcsecond and decreases with distance from the source. The ionisation x_e~0.2-0.6 gently rises for the first 500 AU of the flow and shows two re-ionisation events further away from the origin. The T_e varies along the flow between 10^4 K and 3x10^4 K. The (radial) outflow velocities are ~ 80-160 km...
18. Retired A Stars and Their Companions VI. A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD200964
CERN Document Server
Johnson, John Asher; Howard, Andrew W; Clubb, Kelsey I; Ford, Eric B; Bowler, Brendan P; Henry, Gregory W; Fischer, Debra A; Marcy, Geoffrey W; Brewer, John M; Schwab, Christian; Reffert, Sabine; Lowe, Thomas B
2010-01-01
We report radial velocity measurements of the G-type subgiants 24 Sextanis (=HD90043) and HD200964. Both are massive, evolved stars that exhibit periodic variations due to the presence of a pair of Jovian planets. Photometric monitoring with the T12 0.80m APT at Fairborn Observatory demonstrates both stars to be constant in brightness to <= 0.002 mag, thus strengthening the planetary interpretation of the radial velocity variations. 24 Sex b,c have orbital periods of 453.8 days and 883~days, corresponding to semimajor axes 1.333 AU and 2.08 AU, and minimum masses (Msini) 1.99 Mjup and 0.86 Mjup, assuming a stellar mass 1.54 Msun. HD200964 b,c have orbital periods of 613.8 days and 825 days, corresponding to semimajor axes 1.601 AU and 1.95 AU, and minimum masses 1.85 Mjup and 0.90 Mjup, assuming M* = 1.44 Msun. We also carry out dynamical simulations to properly account for gravitational interactions between the planets. Most, if not all, of the dynamically stable solutions include crossing orbits, suggest...
19. Regular frequency patterns in the young delta Scuti star HD 261711 observed by the CoRoT and MOST satellites
CERN Document Server
Zwintz, K; Guenther, D B; Ryabchikova, T; Baglin, A; Themessl, N; Barnes, T G; Matthews, J M; Auvergne, M; Bohlender, D; Chaintreuil, S; Kuschnig, R; Moffat, A F J; Rowe, J F; Rucinski, S M; Sasselov, D; Weiss, W W
2013-01-01
We concentrate on an asteroseismological study of HD 261711, a rather hot delta Scuti type pulsating member of the young open cluster NGC 2264 located at the blue border of the instability region. HD 261711 was discovered to be a pre-main sequence delta Scuti star using the time series photometry obtained by the MOST satellite in 2006. High-precision, time-series photometry of HD 261711 was obtained by the MOST and CoRoT satellites in 4 separate new observing runs that are put into context with the star's fundamental atmospheric parameters obtained from spectroscopy. With the new MOST data set from 2011/12 and the two CoRoT light curves from 2008 and 2011/12, the delta Scuti variability was confirmed and regular groups of frequencies were discovered. The two pulsation frequencies identified in the data from the first MOST observing run in 2006 are confirmed and 23 new delta Scuti-type frequencies were discovered using the CoRoT data. Weighted average frequencies for each group are related to l=0 and l=1 p-mod...
20. MagAO Imaging of Long-period Objects (MILO). II. A Puzzling White Dwarf around the Sun-like Star HD 11112
CERN Document Server
Rodigas, Timothy J; Simon, Amelie; Arriagada, Pamela; Faherty, Jackie; Anglada-Escude, Guillem; Mamajek, Eric E; Weinberger, Alycia; Butler, R Paul; Males, Jared R; Morzinski, Katie; Close, Laird M; Hinz, Philip M; Bailey, Jeremy; Carter, Brad; Jenkins, James S; Jones, Hugh; O'Toole, Simon; Tinney, C G; Wittenmyer, Rob; Debes, John
2016-01-01
HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect the object (HD 11112B) at a separation of 2\\fasec 2 (100 AU) at multiple wavelengths spanning 0.6-4 \\microns ~and show that it is most likely a gravitationally-bound cool white dwarf. Modeling its spectral energy distribution (SED) suggests that its mass is 0.9-1.1 \\msun, which corresponds to very high-eccentricity, near edge-on orbits from Markov chain Monte Carlo analysis of the RV and imaging data together. The total age of the white dwarf is $>2\\sigma$ discrepant with that of the primary star under most assumptions. The problem can be resolved if the white dwarf progenitor was initially a double white dwarf binary that then merged into the observed high-mass white dwarf. HD 11112B is a unique and intriguing benchmark object that can be used to calibrate ...
1. On the X-ray and optical properties of the Be star HD 110432: a very hard-thermal X-ray emitter
Science.gov (United States)
Lopes de Oliveira, R.; Motch, C.; Smith, M. A.; Negueruela, I.; Torrejón, J. M.
2007-11-01
HD 110432 is the first proposed, and best studied, member of a growing group of Be stars with X-ray properties similar to γ Cas. These stars exhibit hard-thermal X-rays that are variable on all measurable timescales. This emission contrasts with the soft emission of “normal" massive stars and with the non-thermal emission of all well known Be/X-ray binaries - so far, all Be + neutron star systems. In this work we present X-ray spectral and timing properties of HD 110432 from three XMM-Newton observations in addition to new optical spectroscopic observations. Like γ Cas, the X-rays of HD 110432 appear to have a thermal origin, as supported by strongly ionized Fe XXV and Fe XXVI lines detected in emission. A fluorescent iron feature at 6.4 keV is present in all observations, while the Fe XXVI Lyβ line is present in two of them. Its X-ray spectrum, complex and time variable, is well described in each observation by three thermal plasmas with temperatures ranging between 0.2-0.7, 3-6, and 16-37 keV. Thus, HD 110432 has the hottest thermal plasma of any known Be star. A sub-solar iron abundance (~0.3-0.5 ×Z_Fe,⊙) is derived for the hottest plasma, while lines of less excited ions at longer wavelengths are consistent with solar abundances. The star has a moderate 0.2-12 keV luminosity of ~5×1032 erg s-1. The intensity of the X-ray emission is strongly variable. Recurrent flare-like events on time scales as short as ~10 s are superimposed over a basal flux which varies on timescales of ~5-10×103 s, followed by similarly rapid hardness variabilities. There is no evidence for coherent oscillations, and an upper limit of ~2.5% is derived on the pulsed fraction for short pulsations from 0.005 to 2.5 Hz. In the optical region the strong and quasi-symmetrical profile of the Hα line (EW ~ -60 Å) as well as the detection of several metallic lines in emission strongly suggest a dense and/or large circumstellar disk. Also, the double-peaked profiles of metallic lines
2. Dynamics of the circumstellar gas in the Herbig Ae stars BF Orionis, SV Cephei, WW Vulpeculae and XY Persei
CERN Document Server
Mora, A; Natta, A; Grady, C A; De Winter, D; Davies, J K; Ferlet, R; Harris, A W; Miranda, L F; Montesinos, B; Oudmaijer, R D; Palacios, J; Quirrenbach, Andreas G; Rauer, H; Alberdi, A; Cameron, A; Deeg, H J; Garzón, F; Horne, K; Merin, B; Penny, A; Schneider, J; Solano, E; Tsapras, Y; Wesselius, P R
2004-01-01
We present high resolution (lambda / Delta_lambda = 49000) echelle spectra of the intermediate mass, pre-main sequence stars BF Ori, SV Cep, WW Wul and XY Per. The spectra cover the range 3800-5900 angstroms and monitor the stars on time scales of months and days. All spectra show a large number of Balmer and metallic lines with variable blueshifted and redshifted absorption features superimposed to the photospheric stellar spectra. Synthetic Kurucz models are used to estimate rotational velocities, effective temperatures and gravities of the stars. The best photospheric models are subtracted from each observed spectrum to determine the variable absorption features due to the circumstellar gas; those features are characterized in terms of their velocity, v, dispersion velocity, Delta v, and residual absorption, R_max. The absorption components detected in each spectrum can be grouped by their similar radial velocities and are interpreted as the signature of the dynamical evolution of gaseous clumps with, in m...
3. Signs of Planetary Formation in the Disk of HD169142
Science.gov (United States)
Osorio, M.; Anglada, G.; Carrasco-Gonzalez, C.; Torrelles, J. M.; D'Alessio, P.; Rodriguez, L. F.; Calvet, N.; Gomez, J. F.; Mayén-Gijón, J. M.; Dent, W.
2013-07-01
We present 7mm continuum observations at subarcsecond angular resolution, as well as detailed modeling of the disk surrounding the nearby Herbig AeBe star HD 169142. Our modeling of the SED indicates that the system is in an advanced stage of evolution, in which infall and outflow processes have almost halted, and the dust particles have begun to coagulate and settle towards the disk mid-plane to eventually form planetesimals. Our high angular resolution (0."15) VLA observations reveal a region of enhanced 7mm emission with internal substructure, with several local emission peaks at radii 20-40 AU. We interpret these features as signs of planetary formation.
4. Revealing the sub-AU asymmetries of the inner dust rim in the disk around the Herbig Ae star R Coronae Austrinae
Science.gov (United States)
Kraus, S.; Hofmann, K.-H.; Malbet, F.; Meilland, A.; Natta, A.; Schertl, D.; Stee, P.; Weigelt, G.
2009-12-01
Context: Unveiling the structure of the disks around intermediate-mass pre-main-sequence stars (Herbig Ae/Be stars) is essential for our understanding of the star and planet formation process. In particular, models predict that in the innermost AU around the star, the dust disk forms a “puffed-up” inner rim, which should result in a strongly asymmetric brightness distribution for disks seen under intermediate inclination. Aims: Our aim is to constrain the sub-AU geometry of the inner disk around the Herbig Ae star R CrA and search for the predicted asymmetries. Methods: Using the VLTI/AMBER long-baseline interferometer, we obtained 24 near-infrared (H- and K-band) spectro-interferometric observations on R CrA. Observing with three telescopes in a linear array configuration, each data set samples three equally spaced points in the visibility function, providing direct information about the radial intensity profile. In addition, the observations cover a wide position angle range (~97°), also probing the position angle dependence of the source brightness distribution. Results: In the derived visibility function, we detect the signatures of an extended (Gaussian FWHM ~ 25 mas) and a compact component (Gaussian FWHM ~ 5.8 mas), with the compact component contributing about two-thirds of the total flux (both in H- and K-band). The brightness distribution is highly asymmetric, as indicated by the strong closure phases (up to ~40°) and the detected position angle dependence of the visibilities and closure phases. To interpret these asymmetries, we employ various geometric as well as physical models, including a binary model, a skewed ring model, and a puffed-up inner rim model with a vertical or curved rim shape. For the binary and vertical rim model, no acceptable fits could be obtained. On the other hand, the skewed ring model and the curved puffed-up inner rim model allow us to simultaneously reproduce the measured visibilities and closure phases. From these
5. Multi-level 3D non-LTE computations of lithium lines in the metal-poor halo stars HD140283 and HD84937
OpenAIRE
Asplund, M.; Carlsson, M; Botnen, A
2003-01-01
The lithium abundances in metal-poor halo stars are of importance for cosmology, galaxy evolution and stellar structure. In an attempt to study possible systematic errors in the derived Li abundances, the line formation of LiI lines has been investigated by means of realistic 3D hydrodynamical model atmospheres of halo stars and 3D non-LTE radiative transfer calculations. These are the first detailed 3D non-LTE computations reported employing a multi-level atomic model showing that such probl...
6. XMM-Newton Observations of HD189733 During Planetary Transits. X-rays Interaction Between Hot Jupiters and the Host Star.
Science.gov (United States)
Pillitteri, Ignazio; Wolk, S. J.; Cohen, O.; Kashyap, V.; Knutson, H.; Lisse, C. M.
2010-03-01
The irradiation of X-rays from host stars on their nearby gas-giant planets can cause excess heating of the planet which can induce mass loss. Further, it has been argued that the magnetic fields of the two bodies can interact. We present XMM-Newton observations of HD 189733 during the eclipse and planetary transit of its hot jupiter planet HD 189733b in order to investigate any effects of the interaction between the host star and the planet in X-rays. We observe a softening of X-ray spectrum at level of 2 sigmas during the 2009 secondary eclipse. It is followed at 3 ks by an enhancement of the X-ray flux likely due to a flare. No remarkable effects are seen in 2007 transit. Magneto-Hydro-Dynamical (MHD) simulations show that the plasma spectrum could get softer during the eclipse. Further, a region of high plasma density on the stellar corona, and displaced from the planet-star line, should form due to the interaction of magnetic fields of star and planet. The magnetic activity in this region is enhanced and should cause frequent transients. The X-ray observations suggest that these model predictions are globally correct. Despite the simple model adopted and the lack of precise parameters, effects of the interaction of stars and their nearby planets appear to observable in X-rays. X-ray observations allow to probe the structuring and the strength of the complex magnetosphere of the star+planet system.
7. The Diverse Origins of Neutron-capture Elements in the Metal-poor Star HD 94028: Possible Detection of Products of i-Process Nucleosynthesis
Science.gov (United States)
Roederer, Ian U.; Karakas, Amanda I.; Pignatari, Marco; Herwig, Falk
2016-04-01
We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = ‑1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = ‑0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy. These data are associated with Program 072.B-0585(A), PI. Silva. Some data presented in this paper were obtained from the Barbara A. Mikulski Archive for Space Telescopes (MAST). The Space Telescope Science Institute
8. The HARPS search southern extra-solar planets. VII. A very hot jupiter orbiti HD 212301
DEFF Research Database (Denmark)
Lo Curto, G.; Mayor, M.; Clausen, J.V.;
2006-01-01
Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs......Stars: individual : HD212301 - stars : planetary systems - techniques : radial velocities - techniques: spectroscopic - instrumentation : spectrographs...
9. Discovery of a magnetic field in the O9 sub-giant star HD 57682 by the MiMeS Collaboration
CERN Document Server
Grunhut, J H; Marcolino, W L F; Petit, V; Henrichs, H F; Cohen, D H; Alecian, E; Bohlender, D; Bouret, J -C; Kochukhov, O; Neiner, C; St-Louis, N; Townsend, R H D
2009-01-01
We report the detection of a strong, organised magnetic field in the O9IV star HD 57682, using spectropolarimetric observations obtained with ESPaDOnS at the 3.6-m Canada-France-Hawaii Telescope within the context of the Magnetism in Massive Stars (MiMeS) Large Program. From the fitting of our spectra using NLTE model atmospheres we determined that HD 57682 is a $17^{+19}_{-9}$ M$_{\\odot}$ star with a radius of $7.0^{+2.4}_{-1.8}$ R$_\\odot$, and a relatively low mass-loss rate of $1.4^{+3.1}_{-0.95}\\times10^{-9}$ M$_{\\odot}$ yr$^{-1}$. The photospheric absorption lines are narrow, and we use the Fourier transform technique to infer $v\\sin i=15\\pm3$ km s$^{-1}$. This $v\\sin i$ implies a maximum rotational period of 31.5 d, a value qualitatively consistent with the observed variability of the optical absorption and emission lines, as well as the Stokes $V$ profiles and longitudinal field. Using a Bayesian analysis of the velocity-resolved Stokes $V$ profiles to infer the magnetic field characteristics, we tenta...
10. ELODIE metallicity-biased search for transiting Hot Jupiters II. A very hot Jupiter transiting the bright K star HD189733
CERN Document Server
Bouchy, F; Mayor, M; Moutou, C; Pont, F; Iribarne, N; Silva, R D; Ilovaisky, S A; Queloz, D; Santos, N; Ségransan, D; Zucker, S; Bouchy, Francois; Udry, Stephane; Mayor, Michel; Moutou, Claire; Pont, Frederic; Iribarne, Nicolas; Silva, Ronaldo Da; Ilovaisky, Sergio; Queloz, Didier; Santos, Nuno; Segransan, Damien; Zucker, Shay
2005-01-01
Among the 160 known exoplanets, mainly detected in large radial-velocity surveys, only 8 have a characterization of their actual mass and radius thanks to the two complementary methods of detection: radial velocities and photometric transit. We started in March 2004 an exoplanet-search programme biased toward high-metallicity stars which are more frequently host extra-solar planets. This survey aims to detect close-in giant planets, which are most likely to transit their host star. For this programme, high-precision radial velocities are measured with the ELODIE fiber-fed spectrograph on the 1.93-m telescope, and high-precision photometry is obtained with the CCD Camera on the 1.20-m telescope, both at the Haute-Provence Observatory. We report here the discovery of a new transiting hot Jupiter orbiting the star HD189733. The planetary nature of this object is confirmed by the observation of both the spectroscopic and photometric transits. The exoplanet HD189733b, with an orbital period of 2.219 days, has one ...
11. The TRENDS High-Contrast Imaging Survey. V. Discovery of an Old and Cold Benchmark T-dwarf Orbiting the Nearby G-star HD 19467
CERN Document Server
Crepp, Justin R; Howard, Andrew W; Marcy, Geoffrey W; Brewer, John; Fischer, Debra A; Wright, Jason T; Isaacson, Howard
2013-01-01
The nearby Sun-like star HD 19467 shows a subtle radial velocity (RV) acceleration of -1.37+/-0.09 m/s/yr over an 16.9 year time baseline (an RV trend), hinting at the existence of a distant orbiting companion. We have obtained high-contrast adaptive optics images of the star using NIRC2 at Keck Observatory and report the direct detection of the body that causes the acceleration. The companion, HD 19467 B, is dK=12.57+/-0.09 mag fainter than its parent star (contrast ratio of 9.4e-6), has blue colors J-K_s=-0.36+/-0.14 (J-H=-0.29+/-0.15), and is separated by 1.653+/-0.004" (51.1+/-1.0 AU). Follow-up astrometric measurements obtained over an 1.1 year time baseline demonstrate physical association through common parallactic and proper motion. We calculate a firm lower-limit of m>51.9^{+3.6}_{-4.3}Mjup for the companion mass from orbital dynamics using a combination of Doppler observations and imaging. We estimate a model-dependent mass of m=56.7^{+4.6}_{-7.2}Mjup from a gyrochronological age of 4.3^{+1.0}_{-1.2...
12. The Diverse Origins of Neutron-Capture Elements in the Metal-Poor Star HD 94028: Possible Detection of Products of i-process Nucleosynthesis
CERN Document Server
Roederer, Ian U; Pignatari, Marco; Herwig, Falk
2016-01-01
We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H]=-1.62+/-0.09) star HD94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s-process; e.g., [Pb/Fe]=+0.79+/-0.32) and rapid neutron-capture process (r-process; e.g., [Eu/Fe]=+0.22+/-0.12), including unusually large molybdenum ([Mo/Fe]=+0.97+/-0.16) and ruthenium ([Ru/Fe]=+0.69+/-0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe]=-0.06+/-0.19). We analyze an archival near-ultraviolet spectrum of HD94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process pa...
13. Velocity Curve Analysis of the Spectroscopic Binary Stars PV Pup, HD 141929, EE Cet and V921 Her by Nonlinear Regression
K. Karami; R. Mohebi
2007-12-01
We use the method introduced by Karami & Mohebi (2007), and Karami & Teimoorinia (2007) which enable us to derive the orbital parameters of the spectroscopic binary stars by the nonlinear least squares of observed . curve fitting (o–c). Using the measured experimental data for radial velocities of the four double-lined spectroscopic binary systems PV Pup, HD 141929, EE Cet and V921 Her, we find both the orbital and the combined spectroscopic elements of these systems. Our numerical results are in good agreement with those obtained using the method of Lehmann-Filhés.
14. Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 I. Spectropolarimetric observations in all four Stokes parameters
CERN Document Server
Rusomarov, N; Piskunov, N; Jeffers, S V; Johns-Krull, C M; Keller, C U; Makaganiuk, V; Rodenhuis, M; Snik, F; Stempels, H C; Valenti, J A
2013-01-01
High-resolution spectropolarimetric observations provide simultaneous information about stellar magnetic field topologies and three-dimensional distributions of chemical elements. Here we present analysis of a unique full Stokes vector spectropolarimetric data set, acquired for the cool magnetic Ap star HD 24712. The goal of our work is to examine circular and linear polarization signatures inside spectral lines and to study variation of the stellar spectrum and magnetic observables as a function of rotational phase. HD 24712 was observed with the HARPSpol instrument at the 3.6-m ESO telescope over a period of 2010-2011. The resulting spectra have S/N ratio of 300-600 and resolving power exceeding 100000. The multiline technique of least-squares deconvolution (LSD) was applied to combine information from the spectral lines of Fe-peak and rare-earth elements. We used the HARPSPol spectra of HD 24712 to study the morphology of the Stokes profile shapes in individual spectral lines and in LSD Stokes profiles cor...
15. MagAO Imaging of Long-period Objects (MILO). I. A Benchmark M Dwarf Companion Exciting a Massive Planet around the Sun-like Star HD 7449
CERN Document Server
Rodigas, Timothy J; Faherty, Jackie; Anglada-Escude, Guillem; Kaib, Nathan; Butler, R Paul; Shectman, Stephen; Weinberger, Alycia; Males, Jared R; Morzinski, Katie M; Close, Laird M; Hinz, Philip M; Crane, Jeffrey D; Thompson, Ian; Teske, Johanna; Diaz, Matias; Minniti, Dante; Lopez-Morales, Mercedes; Adams, Fred C; Boss, Alan P
2015-01-01
We present high-contrast Magellan adaptive optics (MagAO) images of HD 7449, a Sun-like star with one planet and a long-term radial velocity (RV) trend. We unambiguously detect the source of the long-term trend from 0.6-2.15 \\microns ~at a separation of \\about 0\\fasec 54. We use the object's colors and spectral energy distribution to show that it is most likely an M4-M5 dwarf (mass \\about 0.1-0.2 \\msun) at the same distance as the primary and is therefore likely bound. We also present new RVs measured with the Magellan/MIKE and PFS spectrometers and compile these with archival data from CORALIE and HARPS. We use a new Markov chain Monte Carlo procedure to constrain both the mass ($> 0.17$ \\msun ~at 99$\\%$ confidence) and semimajor axis (\\about 18 AU) of the M dwarf companion (HD 7449B). We also refine the parameters of the known massive planet (HD 7449Ab), finding that its minimum mass is $7.8^{+3.7}_{-1.35}$ \\mj, its semimajor axis is $2.33^{+0.01}_{-0.02}$ AU, and its eccentricity is $0.8^{+0.08}_{-0.06}$. ...
16. Application of the Baade-Wesselink method to a pulsating cluster Herbig Ae star: H254 in IC348
CERN Document Server
Ripepi, V; Marconi, M; Catanzaro, G; Claudi, R; Daszyńska-Daszkiewicz, J; Palla, F; Leccia, S; Bernabei, S
2013-01-01
In this paper we present new photometric and radial velocity data for the PMS $\\delta$ Sct star H254, member of the young cluster IC 348. Photometric V,R$_C$,I$_C$ light curves were obtained at the Loiano and Asiago telescopes. The radial velocity data was acquired by means of the SARG@TNG spectrograph. High-resolution spectroscopy allowed us to derive precise stellar parameters and the chemical composition of the star, obtaining: T$_{\\rm eff}$\\,=\\,6750\\,$\\pm$\\,150 K; $\\log g$\\,=\\,4.1\\,$\\pm$\\,0.4 dex; [Fe/H]=-0.07$\\pm$0.12 dex. Photometric and spectroscopic data were used to estimate the total absorption in the $V$ band A$_{\\rm V}$=2.06$\\pm$0.05 mag, in agreement with previous estimates. We adopted the technique of the difference in phase and amplitude between different photometric bands and radial velocities to verify that H254 is (definitely) pulsating in a radial mode. This occurrence allowed us to apply the CORS realization of the Baade--Wesselink method to obtain a value for the linear radius of H254 equ...
17. The structure of disks around Herbig Ae/Be stars as traced by CO ro-vibrational emission
CERN Document Server
van der Plas, G; Waters, L B F M; Dominik, C
2014-01-01
We study the emission and absorption of CO ro-vibrational lines in the spectra of intermediate mass pre-main-sequence stars with the aim to determine both the spatial distribution of the CO gas and its physical properties. We also aim to correlate CO emission properties with disk geometry. Using high-resolution spectra containing fundamental and first overtone CO ro-vibrational emission, observed with CRIRES on the VLT, we probe the physical properties of the circumstellar gas by studying its kinematics and excitation conditions. We detect and spectrally resolve CO fundamental ro-vibrational emission in 12 of the 13 stars observed, and in two cases in absorption. Keeping in mind that we studied a limited sample, we find that the physical properties and spatial distribution of the CO gas correlate with disk geometry. Flaring disks show highly excited CO fundamental emission up to v$_u$ = 5, while self-shadowed disks show CO emission that is not as highly excited. Rotational temperatures range between ~250-2000...
18. Improved Ti II log(gf) Values and Abundance Determinations in the Photospheres of the Metal-Poor Star HD 84937
CERN Document Server
Wood, M P; Sneden, C; Cowan, J J
2013-01-01
Atomic transition probability measurements for 364 lines of Ti II in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrometer are combined with published radiative lifetimes to determine these transition probabilities. The new results are in generally good agreement with previously reported FTS measurements. Use of the new echelle spectrometer, independent radiometric calibration methods, and independent data analysis routines enables a reduction of systematic errors and overall improvement in transition probability accuracy over previous measurements. The new Ti II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ti abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. The Ti abundances derived using Ti II for these two stars match those derived using Ti I and support the relative Ti/...
19. Discovery of a magnetic field in the rapidly rotating O-type secondary of the colliding-wind binary HD 47129 (Plaskett's star)
Science.gov (United States)
Grunhut, J. H.; Wade, G. A.; Leutenegger, M.; Petit, V.; Rauw, G.; Neiner, C.; Martins, F.; Cohen, D. H.; Gagné, M.; Ignace, R.; Mathis, S.; de Mink, S. E.; Moffat, A. F. J.; Owocki, S.; Shultz, M.; Sundqvist, J.; MiMeS Collaboration
2013-01-01
We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star) in the context of the Magnetism in Massive Stars survey. Eight independent Stokes V observations were acquired using the Echelle SpectroPolarimetric Device for the Observations of Stars (ESPaDOnS) spectropolarimeter at the Canada-France-Hawaii Telescope and the Narval spectropolarimeter at the Télescope Bernard Lyot. Using least-squares deconvolution we obtain definite detections of signal in Stokes V in three observations. No significant signal is detected in the diagnostic null (N) spectra. The Zeeman signatures are broad and track the radial velocity of the secondary component; we therefore conclude that the rapidly rotating secondary component is the magnetized star. Correcting the polarized spectra for the line and continuum of the (sharp-lined) primary, we measured the longitudinal magnetic field from each observation. The longitudinal field of the secondary is variable and exhibits extreme values of -810 ± 150 and +680 ± 190 G, implying a minimum surface dipole polar strength of 2850 ± 500 G. In contrast, we derive an upper limit (3σ) to the primary's surface magnetic field of 230 G. The combination of a strong magnetic field and rapid rotation leads us to conclude that the secondary hosts a centrifugal magnetosphere fed through a magnetically confined wind. We revisit the properties of the optical line profiles and X-ray emission - previously interpreted as a consequence of colliding stellar winds - in this context. We conclude that HD 47129 represents a heretofore unique stellar system - a close, massive binary with a rapidly rotating, magnetized component - that will be a rich target for further study.
20. IMPROVED Co i log(gf) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937
Energy Technology Data Exchange (ETDEWEB)
Lawler, J. E. [Department of Physics, University of Wisconsin-Madison, 1150 University Ave., Madison, WI 53706 (United States); Sneden, C. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Cowan, J. J., E-mail: jelawler@wisc.edu, E-mail: chris@verdi.as.utexas.edu, E-mail: jjcowan1@ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)
2015-09-15
New emission branching fraction measurements for 898 lines of the first spectrum of cobalt (Co i) are determined from hollow cathode lamp spectra recorded with the National Solar Observatory 1 m Fourier transform spectrometer on Kitt Peak, AZ and a high-resolution echelle spectrometer. Published radiative lifetimes from laser induced fluorescence measurements are combined with the branching fractions to determine accurate absolute atomic transition probabilities for the 898 lines. Hyperfine structure (hfs) constants for levels of neutral Co in the literature are surveyed and selected values are used to generate complete hfs component patterns for 195 transitions of Co i. These new laboratory data are applied to determine the Co abundance in the Sun and metal-poor star HD 84937, yielding log ϵ(Co) = 4.955 ± 0.007 (σ = 0.059) based on 82 Co i lines and log ϵ(Co) = 2.785 ± 0.008 (σ = 0.065) based on 66 Co i lines, respectively. A Saha or ionization balance test on the photosphere of HD 84937 is performed using 16 UV lines of Co ii, and good agreement is found with the Co i result in this metal-poor ([Fe i/H] = −2.32, [Fe ii/H] = −2.32) dwarf star. The resulting value of [Co/Fe] = +0.14 supports a rise of Co/Fe at low metallicity that has been suggested in other studies.
1. Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188
CERN Document Server
Stateva, I; Budaj, J
2011-01-01
We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abundances of several elements were determined. We conclude that all six stars are Am stars. These stars were put into the context of other Am binaries with 10 < Porb < 200 days and their abundance anomalies discussed in the context of possible tidal effects. There is clear anti-correlation of the Am peculiarities with v sin i. However, there seems to be also a correlation with the eccentricity and may be with the orbital period. The dependence on the temperature, age, mass, and microturbulence was studied as well. The ...
2. Chemical surface inhomogeneities in late B-type stars with Hg and Mn peculiarity I Spot evolution in HD 11753 on short and long time scales
CERN Document Server
Korhonen, H; Briquet, M; Soriano, M Flores; Hubrig, S; Savanov, I; Hackman, T; Ilyin, I V; Eulaers, E; Pessemier, W
2013-01-01
Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods: High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. Results: We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals som...
3. Discovery of a magnetic field in the rapidly-rotating O-type secondary of the colliding-wind binary HD 47129 (Plaskett's star)
CERN Document Server
Grunhut, J H; Leutenegger, M; Petit, V; Rauw, G; Neiner, C; Martins, F; Cohen, D H; Gagné, M; Ignace, R; Mathis, S; de Mink, S E; Moffat, A F J; Owocki, S; Shultz, M; Sundqvist, J
2012-01-01
We report the detection of a strong, organized magnetic field in the secondary component of the massive O8III/I+O7.5V/III double-lined spectroscopic binary system HD 47129 (Plaskett's star), in the context of the Magnetism in Massive Stars (MiMeS) survey. Eight independent Stokes $V$ observations were acquired using the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope and the Narval spectropolarimeter at the T\\'elescope Bernard Lyot. Using Least-Squares Deconvolution we obtain definite detections of signal in Stokes $V$ in 3 observations. No significant signal is detected in the diagnostic null ($N$) spectra. The Zeeman signatures are broad and track the radial velocity of the secondary component; we therefore conclude that the rapidly-rotating secondary component is the magnetized star. Correcting the polarized spectra for the line and continuum of the (sharp-lined) primary, we measured the longitudinal magnetic field from each observation. The longitudinal field of the secondary is variable...
4. A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
CERN Document Server
Sato, Bun'ei; Liu, Yu-Juan; Zhao, Gang; Omiya, Masashi; Harakawa, Hiroki; Nagasawa, Makiko; Wittenmyer, Robert A; Butler, Paul; Song, Nan; He, Wei; Zhao, Fei; Kambe, Eiji; Noguchi, Kunio; Ando, Hiroyasu; Izumiura, Hideyuki; Okada, Norio; Yoshida, Michitoshi; Takeda, Yoichi; Itoh, Yoichi; Kokubo, Eiichiro; Ida, Shigeru
2016-01-01
We report the detection of a double planetary system around the evolved intermediate-mass star HD 47366 from precise radial-velocity measurements at Okayama Astrophysical Observatory, Xinglong Station, and Australian Astronomical Observatory. The star is a K1 giant with a mass of 1.81+-0.13M_sun, a radius of 7.30+-0.33R_sun, and solar metallicity. The planetary system is composed of two giant planets with minimum mass of 1.75^{+0.20}_{-0.17}Mjup and 1.86^{+0.16}_{-0.15}Mjup, orbital period of 363.3^{+2.5}_{-2.4} d and 684.7^{+5.0}_{-4.9} d, and eccentricity of 0.089^{+0.079}_{-0.060} and 0.278^{+0.067}_{-0.094}, respectively, which are derived by a double Keplerian orbital fit to the radial-velocity data. The system adds to the population of multi-giant-planet systems with relatively small orbital separations, which are preferentially found around evolved intermediate-mass stars. Dynamical stability analysis for the system revealed, however, that the best-fit orbits are unstable in the case of a prograde conf...
5. Line formation in winds with enhanced equatorial mass-loss rates and its application to the Wolf-Rayet star HD 50896
International Nuclear Information System (INIS)
Ultraviolet spectra from the ''Copernicus'' satellite of the Wolf-Rayet star HD 50896 show several P-Cygni profiles whose emission component has a larger equivalent width than the absorption component. For lines with saturated absorption components, such as the N V (lambdalambda1239-1243) line, the excess emission is due to thermal emission from the wind. However, for unsaturated lines which are due to scattering, such as the P V (lambdalambda1118-1128) and O VI (lambdalambda1032-1038) lines, the excess emission suggests that the scattering is not spherically symmetric. Based on this premise, a simple model was developed of a stellar wind whose material is concentrated toward the star's equatorial plane. This model was used to investigate the effect on line formation of the distribution of material in the wind and the orientation of the star-wind system with respect to an observer. In addition, the influence of the wind's velocity structure was investigated for two velocity laws which are schematically depicted. The first distribution has the asymptotic behavior expected for a radiatively accelerated wind. The second one has a similar form in the outer region of the wind, but has a velocity plateau at the inner region, as suggested by ultraviolet to infrared continuum fits of Hartmann and Cassinelli (1977). To simplify calculations, the Sobolev escape probability method was used, and the velocity structure was assumed to be spherically symmetric. (Auth.)
6. Improved V II log($gf$) Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937
CERN Document Server
Wood, M P; Hartog, E A Den; Sneden, C; Cowan, J J
2014-01-01
New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Use of two spectrometers, independent radiometric calibration methods, and independent data analysis routines enables a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used t...
7. Improved Ni I log(gf) Values and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937
CERN Document Server
Wood, M P; Sneden, C; Cowan, J J
2014-01-01
Atomic transition probability measurements for 371 Ni I lines in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrograph are combined with published radiative lifetimes to determine these transition probabilities. Generally good agreement is found in comparisons to previously reported Ni I transition probability measurements. Use of the new echelle spectrograph, independent radiometric calibration methods, and independent data analysis routines enable a reduction of systematic errors and overall improvement in transition probability uncertainty over previous measurements. The new Ni I data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ni abundances. Lines covering a wide range of wavelength and excitation potential are used to search for non-LTE effects.
8. NEWLY DISCOVERED PLANETS ORBITING HD 5319, HD 11506, HD 75784 AND HD 10442 FROM THE N2K CONSORTIUM
Energy Technology Data Exchange (ETDEWEB)
Giguere, Matthew J.; Fischer, Debra A.; Brewer, John M. [Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Payne, Matthew J.; Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Isaacson, Howard T. [Department of Astronomy, University of California, Berkeley, Berkeley, California 94720 (United States)
2015-01-20
Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 M {sub Jup}) orbiting stars monitored as part of the Next 2000 target stars (N2K) Doppler Survey program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer planet has an orbital period of 1627.5 days, and the newly discovered inner planet orbits in 223.6 days. A planet has also been discovered orbiting HD 75784 with an orbital period of 341.7 days. There is evidence for a longer period signal; however, several more years of observations are needed to put tight constraints on the Keplerian parameters for the outer planet. Lastly, an additional planet has been detected orbiting HD 10442 with a period of 1043 days.
9. Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium
CERN Document Server
Giguere, Matthew J; Payne, Matthew J; Brewer, John M; Johnson, John Asher; Howard, Andrew W; Isaacson, Howard T
2014-01-01
Initially designed to discover short-period planets, the N2K campaign has since evolved to discover new worlds at large separations from their host stars. Detecting such worlds will help determine the giant planet occurrence at semi-major axes beyond the ice line, where gas giants are thought to mostly form. Here we report four newly-discovered gas giant planets (with minimum masses ranging from 0.4 to 2.1 MJup) orbiting stars monitored as part of the N2K program. Two of these planets orbit stars already known to host planets: HD 5319 and HD 11506. The remaining discoveries reside in previously-unknown planetary systems: HD 10442 and HD 75784. The refined orbital period of the inner planet orbiting HD 5319 is 641 days. The newly-discovered outer planet orbits in 886 days. The large masses combined with the proximity to a 4:3 mean motion resonance make this system a challenge to explain with current formation and migration theories. HD 11506 has one confirmed planet, and here we confirm a second. The outer pla...
10. Know The Star, Know the Planet. IV. A Stellar Companion to the Host star of the Eccentric Exoplanet HD 8673b
CERN Document Server
Roberts,, Lewis C; Neyman, Christopher R; Wu, Yanqin; Riddle, Reed L; Shelton, J Christopher; Angione, John; Baranec, Christoph; Bouchez, Antonin; Bui, Khanh; Burruss, Rick; Burse, Mahesh; Chordia, Pravin; Croner, Ernest; Das, Hillol; Dekany, Richard G; Guiwits, Stephen; Hale, David; Henning, John; Law, Shrinivas Kulkarni Nicholas; McKenna, Dan; Milburn, Jennifer; Palmer, Dean; Punnadi, Sujit; Ramaprakash, A N; Roberts, Jennifer E; Tendulkar, Shriharsh P; Trinh, Thang; Troy, Mitchell; Truong, Tuan; Zolkower, Jeff
2015-01-01
HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identi?ed a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of ?lters with the aim of con?rming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of ?lters. The measured di?erential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to...
11. Magnetic fields and differential rotation on the pre-main sequence II: The early-G star HD 141943 - coronal magnetic field, H-alpha emission and differential rotation
CERN Document Server
Marsden, S C; Vélez, J C Ramírez; Alecian, E; Brown, C J; Carter, B D; Donati, J F; Dunstone, N; Hart, R; Semel, M; Waite, I A
2011-01-01
Spectropolarimetric observations of the pre-main sequence early-G star HD 141943 were obtained at three observing epochs (2007, 2009 and 2010). The observations were obtained using the 3.9-m Anglo-Australian telescope with the UCLES echelle spectrograph and the SEMPOL spectropolarimeter visitor instrument. The brightness and surface magnetic field topologies (given in Paper I) were used to determine the star's surface differential rotation and reconstruct the coronal magnetic field of the star. The coronal magnetic field at the 3 epochs shows on the largest scales that the field structure is dominated by the dipole component with possible evidence for the tilt of the dipole axis shifting between observations. We find very high levels of differential rotation on HD 141943 (~8 times the solar value for the magnetic features and ~5 times solar for the brightness features) similar to that evidenced by another young early-G star, HD 171488. These results indicate that a significant increase in the level of differe...
12. Simultaneous intensive photometry and high resolution spectroscopy of $\\delta$ Scuti stars; 3, Mode identifications and physical calibrations in HD 2724
CERN Document Server
Bossi, M; Núñez, N S
1998-01-01
On the basis of our new simultaneous photometry and spectroscopy (885 uvby differential measurements in 11 nights and 154 spectrograms of the FeII 4508 A region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit of pulsational models to our data, we estimate the inclination of rotational axis to be about 50 deg. and get a reliable identification of 4 modes as well as useful bits of information about the others: no retrograde mode is visible, whereas the star seems to show a certain preference for purely sectorial prograde oscillations. Finally, the attribution of our lowest frequency to the radial fundamental pulsation allows a new calibration of physical parameters. In particular, the gravity can be determined with unusual accuracy and the luminosity evaluation becomes more consistent with the Hipparcos astrometry.
13. The circumstellar shell of the post-ABB star HD 56126: the 12C12C/12C13C isotope ratio and12C16O column density
NARCIS (Netherlands)
Barker, E.J.; Lambert, D.L.
1998-01-01
We have made the first detection of circumstellar absorption lines of the 12C13C A 1Πu-X 1∑g+ (Phillips) system 1-0 band and the 12C16O X 1∑+ first-overtone 2-0 band in the spectrum of the post-AGB star HD 56126 (IRAS 07134+1005). All current detections of circumstellar molecular absorption lines to
14. HD139614: the interferometric case for a group-Ib pre-transitional young disk
CERN Document Server
Labadie, Lucas; Kreplin, Alexander; Lopez, Bruno; Wolf, Sebastian; Weigelt, Gerd; Ertel, Steve; Berger, Jean-Philippe; Pott, Jorg-Uwe; Danchi, William C
2014-01-01
The Herbig Ae star HD 139614 is a group-Ib object, which featureless SED indicates disk flaring and a possible pre-transitional evolutionary stage. We present mid- and near-IR interferometric results collected with MIDI, AMBER and PIONIER with the aim of constraining the spatial structure of the 0.1-10 AU disk region and assess its possible multi-component structure. A two-component disk model composed of an optically thin 2-AU wide inner disk and an outer temperature-gradient disk starting at 5.6 AU reproduces well the observations. This is an additional argument to the idea that group-I HAeBe inner disks could be already in the disk-clearing transient stage. HD 139614 will become a prime target for mid-IR interferometric imaging with the second-generation instrument MATISSE of the VLTI.
15. Very Low-Mass Stellar and Substellar Companions to Solar-like Stars From MARVELS VI: A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646
CERN Document Server
Ma, Bo; Wolszczan, Alex; Muterspaugh, Matthew W; Lee, Brian; Henry, Gregory W; Schneider, Donald P; Martin, Eduardo L; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; da Costa, Luiz Nicolaci; Jiang, Peng; Fiorenzano, A F Martinez; Hernandez, Jonay I Gonzalez; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C; Wan, Xiaoke; Wang, Ji; Wisniewski, John P; Zhao, Bo; Zucker, Shay
2016-01-01
We report the detections of a giant planet (MARVELS-7b) and a brown dwarf candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. It is the first close binary system with more than one substellar circum-primary companion discovered to the best of our knowledge. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using ET at Kitt Peak National Observatory, HRS at HET, the "Classic" spectrograph at the Automatic Spectroscopic Telescope at Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period brown dwarf in this binary. HD 87646 is a close binary with a separation of $\\sim22$ AU between the two stars, estimated using the Hipparcos catalogue and our newly acquired AO image from PALAO on the 200-inch Hale Telescope at Palomar. The primary star in the binary, HD 87646...
16. Sparse aperture masking at the VLT II. Detection limits for the eight debris disks stars $\\beta$ Pic, AU Mic, 49 Cet, $\\eta$ Tel, Fomalhaut, g Lup, HD181327 and HR8799
CERN Document Server
Gauchet, L; Lagrange, A -M; Ehrenreich, D; Bonnefoy, M; Girard, J H; Boccaletti, A
2016-01-01
Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse Aperture masking (SAM) is a high angular resolution technique strongly contributing to probe the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims. We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low mass companions, or to set detection limits. Methods. We observed eight stars presenting debris disks ( $\\beta$ Pictoris, AU Microscopii, 49 Ceti, $\\eta$ Telescopii, Fomalhaut, g Lupi, HD181327 and HR8799) with SAM technique on the NaCo ins...
17. Identifying gaps in flaring Herbig Ae/Be disks using spatially resolved mid-infrared imaging. Are all group I disks transitional?
CERN Document Server
Maaskant, K M; Waters, L B F M; Tielens, A G G M; Dominik, C; Min, M; Verhoeff, A; Meeus, G; Ancker, M E van den
2013-01-01
*Context The evolution of young massive protoplanetary disks toward planetary systems is expected to include the formation of gaps and the depletion of dust and gas. *Aims A special group of flaring disks around Herbig Ae/Be stars do not show prominent silicate emission features. We focus our attention on four key Herbig Ae/Be stars to understand the structural properties responsible for the absence of silicate feature emission. *Methods We investigate Q- and N-band images taken with Subaru/COMICS, Gemini South/T-ReCS and VLT/VISIR. Our radiative transfer modeling solutions require a separation of inner- and outer- disks by a large gap. From this we characterize the radial density structure of dust and PAHs in the disk. *Results The inner edge of the outer disk has a high surface brightness and a typical temperature between ~100-150 K and therefore dominates the emission in the Q-band. We derive radii of the inner edge of the outer disk of 34, 23, 30 and 63 AU for HD97048, HD169142, HD135344B and Oph IRS 48 r...
18. Detailed Abundances of Planet-Hosting Wide Binaries. II. HD80606 + HD80607
CERN Document Server
Mack, Claude E; Schuler, Simon C; Hebb, Leslie; Pepper, Joshua A
2016-01-01
We present a detailed chemical abundance analysis of 15 elements in the planet-hosting wide binary system HD80606 + HD80607 using Keck/HIRES spectra. As in our previous analysis of the planet-hosting wide binary HD20782 + HD20781, we presume that these two G5 dwarf stars formed together and therefore had identical primordial abundances. In this binary, HD80606 hosts an eccentric ($e\\approx0.93$) giant planet at $\\sim$0.5 AU, but HD80607 has no detected planets. If close-in giant planets on eccentric orbits are efficient at scattering rocky planetary material into their host stars, then HD80606 should show evidence of having accreted rocky material while HD80607 should not. Here we show that the trends of abundance versus element condensation temperature for HD80606 and HD80607 are statistically indistinguishable, corroborating the recent result of Saffe et al. This could suggest that both stars accreted similar amounts of rocky material; indeed, our model for the chemical signature of rocky planet accretion i...
19. LOCATING PLANETESIMAL BELTS IN THE MULTIPLE-PLANET SYSTEMS HD 128311, HD 202206, HD 82943, AND HR 8799
International Nuclear Information System (INIS)
In addition to the Sun, six other stars are known to harbor multiple planets and debris disks: HD 69830, HD 38529, HD 128311, HD 202206, HD 82943, and HR 8799. In this paper, we set constraints on the location of the dust-producing planetesimals around the latter four systems. We use a radiative transfer model to analyze the spectral energy distributions of the dust disks (including two new Spitzer IRS spectra presented in this paper), and a dynamical model to assess the long-term stability of the planetesimals' orbits. As members of a small group of stars that show evidence of harboring a multiple planets and planetesimals, their study can help us learn about the diversity of planetary systems.
20. Two Small Planets Transiting HD 3167
CERN Document Server
Vanderburg, Andrew; Duev, Dmitry A; Jensen-Clem, Rebecca; Latham, David W; Mayo, Andrew W; Baranec, Christoph; Berlind, Perry; Kulkarni, Shrinivas; Law, Nicholas M; Nieberding, Megan N; Riddle, Reed; Salama, Maissa
2016-01-01
We report the discovery of two super-Earth-sized planets transiting the bright (V = 8.94, K = 7.07) nearby late G-dwarf HD 3167, using data collected by the K2 mission. The inner planet, HD 3167 b, has a radius of 1.6 R_e and an ultra-short orbital period of only 0.96 days. The outer planet, HD 3167 c, has a radius of 2.9 R_e and orbits its host star every 29.85 days. At a distance of just 45.8 +/- 2.2 pc, HD 3167 is one of the closest and brightest stars hosting multiple transiting planets, making HD 3167 b and c well suited for follow-up observations. The star is chromospherically inactive and slowly rotating, ideal for radial velocity observations to measure the planets' masses. The outer planet is large enough that it likely has a thick gaseous envelope which could be studied via transmission spectroscopy. Planets transiting bright, nearby stars like HD 3167 are valuable objects to study leading up to the launch of the James Webb Space Telescope.
1. The Multiple System HD 27638
CERN Document Server
Torres, G
2005-01-01
We report spectroscopic observations of HD 27638B, the secondary in a visual binary in which the physically associated primary (separation approximately 19 arcsec) is a B9V star. The secondary shows strong Li 6708 absorption suggesting youth, and has attracted attention in the past as a candidate post-T Tauri star although this has subsequently been ruled out. It was previously known to be a double-lined spectroscopic binary (F8+G6) with a period of 17.6 days, and to show velocity residuals indicating a more distant massive third companion with a period of at least 8 years. Based on our radial velocity measurements covering more than two cycles of the outer orbit, along with other measurements, we derive an accurate triple orbital solution giving an outer period of 9.447 +/- 0.017 yr. The third object is more massive than either of the other two components of HD 27638B, but is not apparent in the spectra. We derive absolute visual magnitudes and effective temperatures for the three visible stars in HD 27638. ...
2. Jets and outflows from pre main sequence stars
Science.gov (United States)
Wassell, Edward Joseph, III
2009-09-01
Extensive research has been done on the evolution of young low mass T Tauri stars (TTS), and a paradigm has been developed that successfully explains how the star grows by the accretion of matter from a circumstellar disk. It is currently a matter of debate whether or not the same paradigm can be applied to the higher mass counterpart Herbig Ae stars. In this dissertation, I propose to address this issue. By investigating a wide range of phenomena using ground- based and satellite observing platforms, I will construct detailed observational pictures of the two prototypical Herbig Ae stars, HD163296 and AB Aur. Then, I will test whether or not this model can explain all the phenomena associated with these two stars. First, my research characterized the bipolar collimated outflow from HD163296. Using narrowband coronagraphic imagery with the Goddard Fabry-Perot, I discovered a chain of six previously unreported Herbig-Haro (HH) knots along the redshifted counterjet spanning greater than 27 arcseconds, and three HH knots along the blueshifted jet. Combining Hubble Space Telescope imagery and spectroscopy, I found a striking asymmetry in velocity, momentum and ionization between the two lobes of the outflow. Such asymmetries have been found in TTS, and can readily be explained through the same paradigm of magnetospheric accretion successfully applied to TTS. Next, by piecing together a wide range of data for AB Aur, I found evidence for magnetospheric accretion with the detection of excess continuum emission and semi-forbidden line emission in the ultraviolet. Reviewing archival spectra from the International Ultraviolet Explorer for AB Aur and five other Herbig Ae stars known to be powering microjets, I found a correlation between the Magnesium II wind absorption profile and inclination, which correlation strongly suggests that AB Aur is also powering a microjet, although currently, high resolution imagers have failed to detect jet signatures.
3. Dust and Polycyclic Aromatic Hydrocarbon in the Pre-Transitional Disk around HD 169142
CERN Document Server
Seok, Ji Yeon
2015-01-01
The pre-transitional disk around the Herbig Ae star HD 169142 shows a complex structure of possible ongoing planet formation in dust thermal emission from the near infrared (IR) to millimeter wavelength range. Also, a distinct set of broad emission features at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 $\\mu$m, commonly attributed to polycyclic aromatic hydrocarbons (PAHs), are detected prominently in the HD 169142 disk. We model the spectral energy distribution (SED) as well as the PAH emission features of the HD 169142 disk simultaneously with porous dust and astronomical-PAHs taking into account the spatially resolved disk structure. Our porous dust model consisting of three distinct components that are primarily concentrated in the inner ring, middle ring, and outer disk, respectively, provides an excellent fit to the entire SED, and the PAH model closely reproduces the observed PAH features. The accretion of ice mantles onto porous dust aggregates occurs between ~16 AU and 60 AU, which overlaps with the spatial e...
4. Gas in the protoplanetary disc of HD 169142: Herschel's view
CERN Document Server
Meeus, G; Woitke, P; Montesinos, B; Mendigutía, I; Riviere-Marichalar, P; Eiroa, C; Mathews, G S; Vandenbussche, B; Howard, C D; Roberge, A; Sandell, G; Duchêne, G; Ménard, F; Grady, C A; Dent, W R F; Kamp, I; Augereau, J C; Thi, W F; Tilling, I; Alacid, J M; Andrews, S; Ardila, D R; Aresu, G; Barrado, D; Brittain, S; Ciardi, D R; Danchi, W; Fedele, D; de Gregorio-Monsalvo, I; Heras, A; Huelamo, N; Krivov, A; Lebreton, J; Liseau, R; Martin-Zaidi, C; Mora, A; Morales-Calderon, M; Nomura, H; Pantin, E; Pascucci, I; Phillips, N; Podio, L; Poelman, D R; Ramsay, S; Riaz, B; Rice, K; Solano, E; Walker, H; White, G J; Williams, J P; Wright, G
2010-01-01
In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the Open Time Key Project GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 micron, [CII] 157.7 micron, CO 72.8 and 90.2 micron, and o-H2O 78.7 and 179.5 micron. We only detect the [OI] 63.2 micron line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and 12/13CO data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ...
5. Sparse aperture masking at the VLT. II. Detection limits for the eight debris disks stars β Pic, AU Mic, 49 Cet, η Tel, Fomalhaut, g Lup, HD 181327 and HR 8799
Science.gov (United States)
Gauchet, L.; Lacour, S.; Lagrange, A.-M.; Ehrenreich, D.; Bonnefoy, M.; Girard, J. H.; Boccaletti, A.
2016-10-01
Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse aperture masking (SAM) is a high angular resolution technique strongly contributing to probing the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims: We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low-mass companions, or to set detection limits. Methods: We observed eight stars presenting debris disks (β Pictoris, AU Microscopii, 49 Ceti, η Telescopii, Fomalhaut, g Lupi, HD 181327, and HR 8799) with SAM technique on the NaCo instrument at the Very Large Telescope (VLT). Results: No close companions were detected using closure phase information under 0.5'' of separation from the parent stars. We obtained magnitude detection limits that we converted to Jupiter masses detection limits using theoretical isochrones from evolutionary models. Conclusions: We derived upper mass limits on the presence of companions in the area of a few times the telescope's diffraction limits around each target star. Based on observations collected at the European Southern Observatory (ESO) during runs 087.C-0450(A), 087.C-0450(B) 087.C-0750(A), 088.C-0358(A).All magnitude detection limits maps are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A31
6. Special Feature: Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars
Science.gov (United States)
Hill, Hugh G. M.; Grady, Carol A.; Nuth, Joseph A., III; Hallenbeck, Susan L.; Sitko, Michael L.
2001-02-01
Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formationextending possibly hundreds of astronomical units (AU) from the sunand that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant effect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with "clean" catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology.
7. Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars.
Science.gov (United States)
Hill, H G; Grady, C A; Nuth, J A; Hallenbeck, S L; Sitko, M L
2001-02-27
Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation-extending possibly hundreds of astronomical units (AU) from the sun-and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant effect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with "clean" catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology. PMID:11226213
8. HD 12098 and Other Results from Nainital–Cape Survey
V. Girish
2005-06-01
Nainital;Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere.We discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. We summarize here the observations of HD 12098 and briefly discuss the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.
9. New visual companions of solar-type stars within 25 pc
OpenAIRE
Chini, R.; Fuhrmann, K.; Domínguez, A. Barr; Nuñez, F. Pozo; Westhues, C.; Hodapp, K.
2013-01-01
We report the discovery of faint common-proper-motion companions to the nearby southern solar-type stars HD43162, HD67199, HD114837, HD114853, HD129502, HD165185, HD197214, and HD212330 from near-infrared imaging and astrometry. We also confirm the previously identified tertiary components around HD165401 and HD188088. Since the majority of these stars were already known as binaries, they ascend now to higher-level systems. A particularly interesting case is the G6.5V BYDra-type variable HD43...
10. Reproducing the observed abundances in RCB and HdC stars with post-double degenerate merger models - constraints on merger and post-merger simulations and physics processes
CERN Document Server
Menon, Athira; Denissenkov, Pavel A; Clayton, Geoffrey C; Staff, Jan; Pignatari, Marco; Paxton, Bill
2012-01-01
The R Coronae Borealis (RCB) stars along with the H-deficient Carbon stars (HdCs) and Extreme Helium stars (EHes), are believed to be the results of He-CO WD mergers. Their H-poor, C-rich atmospheres are characterized by very unusual isotopic ratios such as extremely low O16/O18 ~ 1 - 10, C12/C13 >= 100, and enhancements up to 2.6 dex in F and in s-process elements from Zn to La, compared to solar. As shown before such O-isotopic ratios cannot result from the dynamic double-degenerate merger phase. We therefore investigate now the role of the long-term post-merger evolution and nucleosynthesis. We construct post-merger 1D spherical models based on realistic merger progenitor models and the outcome of our previous hydrodynamic simulations and follow their evolution into the RCB domain of the HR diagram. Along with surface convection zones, we adopt a model for extra mixing that is meant to represent processes driven by rotation originating in the dynamical merger. We perform complete multi-zone post-processing...
11. Differential asteroseismic study of seismic twins observed by CoRoT; Comparison of HD 175272 with HD 181420
CERN Document Server
Ozel, N; Dupret, M A; Bruntt, H; Barban, C; Deheuvels, S; Garc'\\ia, R A; Michel, E; Samadi, R; Baudin, F; Mathur, S; Régulo, C; Auvergne, M; Morel, P; Pichon, B
2013-01-01
The CoRoT short asteroseismic runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report the observation and modeling of the F5V star HD 175272. Our aim is to define a method for extracting as much information as possible from a noisy oscillation spectrum. We followed a differential approach that consists of using a well-known star as a reference to characterize another star. We used classical tools such as the envelope autocorrelation function to derive the global seismic parameters of the star. We compared HD 175272 with HD 181420 through a linear approach, because they appear to be asteroseismic twins. The comparison with the reference star enables us to substantially enhance the scientific output for HD 175272. First, we determined its global characteristics through a detailed seismic analysis of HD 181420. Second, with our differential approach, we measured the difference of mass, radius and age between HD 175272 and HD 181420. We have deve...
12. Dynamical Spot Evolution in HD 11753
OpenAIRE
Korhonen, H.; Hubrig, S.; Briquet, Maryline; González, J.F.; Savanov, I.
2011-01-01
Our recent studies of HD 11753, a late B-type star showing a HgMn peculiarity for the first time revealed the presence of a fast dynamical evolution of chemical spots on the surface of this chemically peculiar early-type star. These observations suggest a hitherto unknown physical process operating in stars with outer radiative envelopes. Furthermore, we have also discovered existence of magnetic fields on HgMn stars that were up to now considered non-magnetic. Here we will discuss the dyna...
13. Hardware Implementation of AES
Directory of Open Access Journals (Sweden)
Aakrati Chaturvedi
2014-01-01
Full Text Available The Advanced Encryption Standard algorithm can be efficiently programmed in software and implemented in hardware. Field Programmable Gate Array (FPGA devices are considered as efficient and cost effective solution for hardware. This research is in context to efficient hardware implementation of AES algorithm with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. This research is in context to efficient hardware implementation of AES algorithm with 128-192-256 key all in one module with language platform as VHDL (Very High Speed Integrated Circuit Hardware Description language. The software part has been created, processed and simulated through Xilinx ISE 9.2. A compact design approach has been chosen to implement the algorithm with minimal hardware. As for hardware, Spartan 3AN family device (XC3S700A device is used
14. Variability of Disk Emission in Pre-Main Sequence and Related Stars. III. Exploring Structural Changes in the Pre-transitional Disk in HD 169142
CERN Document Server
Wagner, Kevin R; Grady, Carol A; Whitney, Barbara A; Swearingen, Jeremy R; Champney, Elizabeth H; Johnson, Alexa N; Werren, Chelsea; Russell, Ray W; Schneider, Glenn H; Momose, Munetake; Muto, Takayuki; Inoue, Akio K; Lauroesch, James T; Brown, Alexander; Fukagawa, Misato; Currie, Thayne M; Hornbeck, Jeremy; Wisniewski, John P; Woodgate, Bruce E
2014-01-01
We present near-IR and far-UV observations of the pre-transitional (gapped) disk in HD 169142 using NASA's Infrared Telescope Facility and Hubble Space Telescope. The combination of our data along with existing data sets into the broadband spectral energy distribution reveals variability of up to 45% between ~1.5-10 {\\mu}m over a maximum timescale of 10 years. All observations known to us separate into two distinct states corresponding to a high near-IR state in the pre-2000 epoch and a low state in the post-2000 epoch, indicating activity within the <1 AU region of the disk. Through analysis of the Pa {\\beta} and Br {\\gamma} lines in our data we derive a mass accretion rate in May 2013 of (1.5 - 2.7) x 10^-9 Msun/yr. We present a theoretical modeling analysis of the disk in HD 169142 using Monte-Carlo radiative transfer simulation software to explore the conditions and perhaps signs of planetary formation in our collection of 24 years of observations. We find that shifting the outer edge (r = 0.3 AU) of t...
15. Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD 116657, HD 138213, HD 155375, HD 159560, HD 196544 and HD 204188
OpenAIRE
Stateva, I.; Iliev, I. Kh; Budaj, J.
2012-01-01
We continue here the systematic abundance analysis of a sample of Am binaries in order to search for possible abundance anomalies driven by tidal interaction in these binary systems. New CCD observations in two spectral regions (6400-6500, 6660-6760 AA) of HD116657, HD138213, HD155375, HD159560, HD196544 and HD204188 were obtained. Synthetic spectrum analysis was carried out and basic stellar properties, effective temperatures, gravities, projected rotational velocities, masses, ages and abun...
16. MID-INFRARED IMAGING OF THE TRANSITIONAL DISK OF HD 169142: MEASURING THE SIZE OF THE GAP
Energy Technology Data Exchange (ETDEWEB)
Honda, M. [Department of Mathematics and Physics, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293 (Japan); Maaskant, Koen; Waters, L. B. F. M.; Dominik, C.; Mulders, G. D. [Astronomical Institute Anton Pannekoek, University of Amsterdam, P.O. Box 94249, 1090 GE Amsterdam (Netherlands); Okamoto, Y. K. [Institute of Astrophysics and Planetary Sciences, Faculty of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512 (Japan); Kataza, H. [Department of Infrared Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Fukagawa, M. [Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Tielens, A. G. G. M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Min, M. [Astronomical Institute Utrecht, Utrecht University, P.O. Box 80000, 3508 TA Utrecht (Netherlands); Yamashita, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Fujiyoshi, T.; Fujiwara, H. [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Miyata, T.; Sako, S. [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Sakon, I.; Onaka, T. [Department of Astronomy, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2012-06-20
The disk around the Herbig Ae star HD 169142 was imaged and resolved at 18.8 and 24.5 {mu}m using Subaru/COMICS. We interpret the observations using a two-dimensional radiative transfer model and find evidence for the presence of a large gap. The mid-infrared images trace dust that is emitted at the onset of a strong rise in the spectral energy distribution (SED) at 20 {mu}m, and are therefore very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23{sup +3}{sub -5} AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the near-infrared, and an optically thin, geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a strong case for classification as a transitional disk, though improved imaging surveys are needed to support this speculation.
17. Mid-IR imaging of the transitional disk of HD169142: Measuring the size of the gap
CERN Document Server
Honda, M; Okamoto, Y K; Kataza, H; Fukagawa, M; Waters, L B F M; Dominik, C; Tielens, A G G M; Mulders, G D; Min, M; Yamashita, T; Fujiyoshi, T; Miyata, T; Sako, S; Sakon, I; Fujiwara, H; Onaka, T
2012-01-01
The disk around the Herbig Ae star HD\\,169142 was imaged and resolved at 18.8 and 24.5\\,$\\mu$m using Subaru/COMICS. We interpret the observations using a 2D radiative transfer model and find evidence for the presence of a large gap. The MIR images trace dust that emits at the onset of the strong rise in the spectral energy distribution (SED) at 20\\,$\\mu$m, therefore are very sensitive to the location and characteristics of the inner wall of the outer disk and its dust. We determine the location of the wall to be 23$^{+3}_{-5}$\\,AU from the star. An extra component of hot dust must exist close to the star. We find that a hydrostatic optically thick inner disk does not produce enough flux in the NIR and an optically thin geometrically thick component is our solution to fit the SED. Considering the recent findings of gaps and holes in a number of Herbig Ae/Be group I disks, we suggest that such disk structures may be common in group I sources. Classification as group I should be considered a support for classifi...
18. Hubble Space Telescope Observations of the HD 202628 Debris Disk
Science.gov (United States)
Krist, John E.; Stapelfeldt, Karl R.; Bryden, Geoffrey; Plavchan, Peter
2012-01-01
A ring-shaped debris disk around the G2V star HD 202628 (d = 24.4 pc) was imaged in scattered light at visible wavelengths using the coronagraphic mode of the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. The ring is inclined by approx.64deg from face-on, based on the apparent major/minor axis ratio, with the major axis aligned along PA = 130deg. It has inner and outer radii (> 50% maximum surface brightness) of 139 AU and 193 AU in the northwest ansae and 161 AU and 223 AU in the southeast ((Delta)r/r approx. = 0.4). The maximum visible radial extent is approx. 254 AU. With a mean surface brightnesses of V approx. = 24 mag arcsec.(sup -2), this is the faintest debris disk observed to date in reflected light. The center of the ring appears offset from the star by approx.28 AU (deprojected). An ellipse fit to the inner edge has an eccentricity of 0.18 and a = 158 AU. This offset, along with the relatively sharp inner edge of the ring, suggests the influence of a planetary-mass companion. There is a strong similarity with the debris ring around Fomalhaut, though HD 202628 is a more mature star with an estimated age of about 2 Gyr. We also provide surface brightness limits for nine other stars in our study with strong Spitzer excesses around which no debris disks were detected in scattered light (HD 377, HD 7590, HD 38858, HD 45184, HD 73350, HD 135599, HD 145229, HD 187897, and HD 201219).
19. Gas Modelling in the Disc of HD 163296
Science.gov (United States)
Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; Martin-Zaidi, C.; Kamp, I.; Pinte, C.; Sandell, G.; Vacca, W. D.; Menard, F.; Mendigutia, I.; Duchene, G.; Dent, W. R. F.; Aresu, G.; Meijerink, R.; Spaans, M.
2011-01-01
We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry
20. The Pan-Pacific Planet Search. IV. Two super-Jupiters in a 3:5 resonance orbiting the giant star HD33844
CERN Document Server
Wittenmyer, Robert A; Butler, R P; Horner, Jonathan; Wang, Liang; Robertson, Paul; Jones, M I; Jenkins, J S; Brahm, R; Tinney, C G; Mengel, M W; Clark, J
2015-01-01
We report the discovery of two giant planets orbiting the K giant HD 33844 based on radial velocity data from three independent campaigns. The planets move on nearly circular orbits with semimajor axes $a_b=1.60\\pm$0.02 AU and $a_c=2.24\\pm$0.05 AU, and have minimum masses (m sin $i$) of $M_b=1.96\\pm$0.12 Mjup and $M_c=1.76\\pm$0.18 Mjup. Detailed N-body dynamical simulations show that the two planets remain on stable orbits for more than $10^6$ years for low eccentricities, and are most likely trapped in a mutual 3:5 mean-motion resonance.
1. Periodic Variations in Ultraviolet Spectral Lines of the B0.5 Ib Star HD 64760: Evidence for Corotating Wind Streams Rooted in Surface Variations
Science.gov (United States)
Owocki, Stanley P.; Cranmer, Steven R.; Fullerton, Alexander W.
1995-11-01
We discuss recently observed periodic modulations in the UV wind lines of the B-type supergiant HD 64760, with a focus on the peculiar, upwardly bowed shape seen in isoflux contours of the absorption variations plotted against velocity and time. We show that this qualitative impression of bowed contours is quantitatively confirmed by a peak in the phase for the associated periodic variation at very nearly the same line position as the apparent bow minimum. The bowed shape is significant because it indicates that wind variations evolve both blueward and redward, i.e., toward both larger and smaller line-of-sight velocities. We show here, however, that these characteristics arise naturally from absorption by strictly accelerating corotating wind streams seen in projection against the stellar disk. The quite good agreement obtained with the observed profile variations provides strong evidence for corotating stream modulations in this wind.
2. Sensitive survey for 13CO, CN, H2CO, and SO in the disks of T Tauri and Herbig Ae stars II: Stars in $\\rho$ Oph and upper Scorpius
CERN Document Server
Reboussin, L; Simon, M; Grosso, N; Wakelam, V; Di Folco, E; Dutrey, A; Piétu, V
2015-01-01
We attempt to determine the molecular composition of disks around young low-mass stars in the $\\rho$ Oph region and to compare our results with a similar study performed in the Taurus-Auriga region. We used the IRAM 30 m telescope to perform a sensitive search for CN N=2-1 in 29 T Tauri stars located in the $\\rho$ Oph and upper Scorpius regions. $^{13}$CO J=2-1 is observed simultaneously to provide an indication of the level of confusion with the surrounding molecular cloud. The bandpass also contains two transitions of ortho-H$_2$CO, one of SO, and the C$^{17}$O J=2-1 line, which provides complementary information on the nature of the emission. Contamination by molecular cloud in $^{13}$CO and even C$^{17}$O is ubiquitous. The CN detection rate appears to be lower than for the Taurus region, with only four sources being detected (three are attributable to disks). H$_2$CO emission is found more frequently, but appears in general to be due to the surrounding cloud. The weaker emission than in Taurus may sugges...
3. Water ice at the surface of HD 100546 disk
CERN Document Server
Honda, M; Takatsuki, S; Inoue, A K; Nakamoto, T; Fukagawa, M; Tamura, M; Terada, H; Takato, N
2016-01-01
We made near infrared multicolor imaging observations of a disk around Herbig Be star HD100546 using Gemini/NICI. K (2.2\\,$\\mu$m), H$_2$O ice (3.06\\,$\\mu$m), and L'(3.8\\,$\\mu$m) disk images were obtained and we found the 3.1\\,$\\mu$m absorption feature in the scattered light spectrum, likely due to water ice grains at the disk surface. We compared the observed depth of the ice absorption feature with the disk model based on \\cite{Oka2012} including water ice photodesorption effect by stellar UV photons. The observed absorption depth can be explained by the both disk models with/without photodesorption effect within the measurement accuracy, but slightly favors the model with photodesorption effects, implying that the UV photons play an important role on the survival/destruction of ice grains at the Herbig Ae/Be disk surface. Further improvement on the accuracy of the observations of the water ice absorption depth is needed to constrain the disk models.
4. Resolving the inner regions of the HD97048 circumstellar disk with VLT/NACO polarimetric differential imaging
CERN Document Server
Quanz, Sascha P; Apai, Daniel; Wolf, Sebastian; Henning, Thomas
2011-01-01
Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. As most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disk on these scales to constrain the conditions for planet formation. Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD97048 in polarized light. We use VLT/NACO to observe HD97048 in polarimetric differential imaging (PDI) mode in the H and Ks band. We spatially resolve the disk around HD97048 in polarized flux in both filters on scales between ~0.1"-1.0" corresponding to the inner ~16-160 AU. Fitting isophots to the flux calibrated H-band image between 13 - 14 mag/arcsec^2 and 14 - 15 mag/arcsec^2 we derive a apparent disk inclination angle of 34+-5 deg and 47+-2 deg, respectively. The disk position angle in both brightness regimes is almost identical and roughly 80 deg. Along...
5. THE DIVERSE ORIGINS OF NEUTRON-CAPTURE ELEMENTS IN THE METAL-POOR STAR HD 94028: POSSIBLE DETECTION OF PRODUCTS OF i-PROCESS NUCLEOSYNTHESIS
Energy Technology Data Exchange (ETDEWEB)
Roederer, Ian U. [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Karakas, Amanda I. [Research School of Astronomy and Astrophysics, The Australian National University, Canberra ACT 2611 (Australia); Pignatari, Marco [E.A. Milne Centre for Astrophysics, Department of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); Herwig, Falk, E-mail: iur@umich.edu, E-mail: amanda.karakas@monash.edu, E-mail: mpignatari@gmail.com, E-mail: fherwig@uvic.ca [Joint Institute for Nuclear Astrophysics and Center for the Evolution of the Elements (JINA-CEE) (United States)
2016-04-10
We present a detailed analysis of the composition and nucleosynthetic origins of the heavy elements in the metal-poor ([Fe/H] = −1.62 ± 0.09) star HD 94028. Previous studies revealed that this star is mildly enhanced in elements produced by the slow neutron-capture process (s process; e.g., [Pb/Fe] = +0.79 ± 0.32) and rapid neutron-capture process (r process; e.g., [Eu/Fe] = +0.22 ± 0.12), including unusually large molybdenum ([Mo/Fe] = +0.97 ± 0.16) and ruthenium ([Ru/Fe] = +0.69 ± 0.17) enhancements. However, this star is not enhanced in carbon ([C/Fe] = −0.06 ± 0.19). We analyze an archival near-ultraviolet spectrum of HD 94028, collected using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope, and other archival optical spectra collected from ground-based telescopes. We report abundances or upper limits derived from 64 species of 56 elements. We compare these observations with s-process yields from low-metallicity AGB evolution and nucleosynthesis models. No combination of s- and r-process patterns can adequately reproduce the observed abundances, including the super-solar [As/Ge] ratio (+0.99 ± 0.23) and the enhanced [Mo/Fe] and [Ru/Fe] ratios. We can fit these features when including an additional contribution from the intermediate neutron-capture process (i process), which perhaps operated through the ingestion of H in He-burning convective regions in massive stars, super-AGB stars, or low-mass AGB stars. Currently, only the i process appears capable of consistently producing the super-solar [As/Ge] ratios and ratios among neighboring heavy elements found in HD 94028. Other metal-poor stars also show enhanced [As/Ge] ratios, hinting that operation of the i process may have been common in the early Galaxy.
6. BVRI Photometry of nz Gem, HD 73017, HD 77247, RT Vir and 104 Her
Science.gov (United States)
Adelman, Saul J.; Harrell, William L.
We examined single channel differential BVRI photometry of the cool stars NZ Gem, HD 73017, HD 77247, RT Vir and 104 Her obtained by the first author with the Four College Automated Photoelectric Telescope with of order 100 observations taken over two or more years. Four of these stars are Small-Amplitude Red Variables (SARVs). The primary period of NZ Gem (M3 II-IIIs) is about 33.70 days. HD 77247, the shortest period barium star with spectral type K0, has a photometric period of about 82 days which is close to its binary period of 80.53 days. Its check star HD 73017, a non-variable in B, V and R, is variable in I due most likely to a previously unknown cooler companion. RT Vir (M8 III) is found to be a multiperiodic star whose observations are consistent with the 155 day primary period of Lebzelter & Hinkle (2002). 104 Her (M3 III) is also multiperiodic with a primary period of 21.48 days.
7. NEAR-INFRARED SPECTROSCOPY OF POST-AGB STARS
NARCIS (Netherlands)
OUDMAIJER, RD; WATERS, LBFM; VANDERVEEN, WECJ; GEBALLE, TR
1995-01-01
The results of a medium resolution near-infrared spectral survey of 18 post-AGB candidate stars are presented. Most of the stars have near-infrared hydrogen lines in absorption, which is normal for their spectral types. Three stars, HD 101584, HD 179821 and HD 170756 have the CO first overtone bands
8. Aes grave iz Jesenica
OpenAIRE
Bonačić Mandinić, Maja
2009-01-01
U zbirci Arheološkog muzeja u Splitu čuva se primjerak aes grave tipa Apolon/Apolon (RRC 18/1). Pripada emisiji kovnice u Rimu iz 275. do 270. godine prije Krista. Nađen je oko 1901. godine u Jesenicama. Bilo kakve pojedinosti o kontekstu nalaza nisu poznate. Jesenice su selo na oko 200 do 250 m nadmorske visine, na padini Peruna - južna kosa planine Mosor. Uz ostale helenističke nalaze sa šireg područja Jesenica, na potezu uz obalu između Splita i Omiša, ovaj nalaz bi mogao svjedočiti o vezi...
9. The SPHERE view of the planet-forming disk around HD100546
CERN Document Server
Garufi, Antonio; Schmid, Hans Martin; Mulders, Gijs D; Avenhaus, Henning; Boccaletti, Anthony; Ginski, Christian; Langlois, Maud; Stolker, Tomas; Augereau, Jean-Charles; Benisty, Myriam; Lopez, Bruno; Dominik, Carsten; Gratton, Raffaele; Henning, Thomas; Janson, Markus; Menard, Francois; Meyer, Michael R; Pinte, Christophe; Sissa, Elena; Vigan, Arthur; Zurlo, Alice; Bazzon, Andreas; Buenzli, Esther; Bonnefoy, Mickael; Brandner, Wolfgang; Chauvin, Gael; Cheetham, Anthony; Cudel, Maxime; Desidera, Silvano; Feldt, Markus; Galicher, Raphael; Kasper, Markus; Lagrange, Anne-Marie; Lannier, Justine; Maire, Anne-Lise; Mesa, Dino; Mouillet, David; Peretti, Sebastien; Perrot, Clement; Salter, Graeme; Wildi, Francois
2016-01-01
We image with unprecedented spatial resolution and sensitivity disk features that could be potential signs of planet-disk interaction. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD100546 in scattered light. We obtain the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyze with the Pynpoint package. The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to ADI processing) resembles a morphology newly observed in inclined disks. Given the cav...
10. Pre-main-sequence binaries with tidally disrupted discs: the Br gamma in HD 104237
CERN Document Server
Garcia, P J V; Dougados, C; Bacciotti, F; Clausse, J -M; Massi, F; Mérand, A; Petrov, R; Weigelt, G
2013-01-01
Active pre-main-sequence binaries with separations of around ten stellar radii present a wealth of phenomena unobserved in common systems. The study of these objects is extended from Classical T Tauri stars to the Herbig Ae star HD 104237. Spectro-interferometry with the VLTI/AMBER is presented. It is found that the K-band continuum squared visibilities are compatible with a circumbinary disc with a radius of ~0.5 AU. However, a significant fraction (~50 per cent) of the flux is unresolved and not fully accounted by the stellar photospheres. The stars probably don't hold circumstellar discs, in addition to the circumbinary disk, due to the combined effects of inner magnetospheric truncation and outer tidal truncation. This unresolved flux likely arises in compact structures inside the tidally disrupted circumbinary disc. Most ($\\gtrsim 90$ per cent) of the Br gamma line emission is unresolved. The line-to-continuum spectro-astrometry shifts in time, along the direction of the Ly alpha jet known to be driven b...
11. Pro Tools HD
CERN Document Server
Camou, Edouard
2013-01-01
An easy-to-follow guide for using Pro Tools HD 11 effectively.This book is ideal for anyone who already uses ProTools and wants to learn more, or is new to Pro Tools HD and wants to use it effectively in their own audio workstations.
12. The circumstellar shell of the post-AGB star HD 56126 the $^{12}C ^{12}C \\/ ^{12}C ^{13}C$isotope ratio and $^{12}C ^{16}O$ column density
CERN Document Server
Bakker, E J; Lambert, Eric J. Bakker & David L.
1998-01-01
We have made the first detection of circumstellar absorption lines of the 12C13C (Phillips) system 1-0 band and the 12C16O first-overtone 2-0 band in the spectrum of the post-AGB star HD56126 (IRAS07134+1005). The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C12C/12C13C=36+-13, 12C16O/(12C12C+12C13C)=606+-230, and 12C16O/(12C14N+13C14N)=475+-175. The isotopic exchange reaction for 12C12C is too slow to significantly alter the 12C12C/12C13C ratio and the 12C12C to 12C13C ratio a good measure of half the carbon isotope ratio: 12C/13C=2 X 12C12C/12C13C=72+-26. A fit of the 12C12C excitation model of van Dishoeck & Black (1982) to the relative population distribution of 12C12C yields n sigma / I = 3.3 +- 1.0 X 1e-14. At r=1e16cm this translates in n=1.7e7cm-3 and dM/dt=2.5e-4Msol/year.
13. Lights, camera, A&E.
Science.gov (United States)
Gould, Mark
Channel 4 series 24 Hours in A&E was one of the television highlights of 2011. Filmed at King's College Hospital in London, it showed the reality of life in an A&E department and may have improved the public's understanding of nursing. PMID:22324233
14. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser
Science.gov (United States)
Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.
2016-08-01
This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.
15. The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing
Science.gov (United States)
Wisniewski, John P.; Clampin, Mark; Grady, Carol A.; Ardila, David R.; Ford, Holland C.; Golimowski, David A.; Illingworth, Garth D.; Krist, John E.
2008-01-01
We present the first multi-color view of the scattered light disk of the Herbig Ae star HD 163296, based on coronagraphic observations from the Hubble Space Telescope Advanced Camera for Surveys (ACS). Radial profile fits of the surface brightness along the disk's semi-major axis indicates that the disk is not continuously flared, and extends to approx.540 AU. The disk's color (V-I)=1.1 at a radial distance of 3.5" is redder than the observed stellar color (V-I)=0.15. This red disk color might be indicative of either an evolution in the grain size distribution (i.e. grain growth) and/or composition, both of which would be consistent with the observed non-flared geometry of the outer disk. We also identify a single ansa morphological structure in our F435W ACS data, which is absent from earlier epoch F606W and F814W ACS data, but corresponds to one of the two ansa observed in archival HST STIS coronagraphic data. Following transformation to similar band-passes, we find that the scattered light disk of HD 163296 is 1 mag arcsec(sup -2) fainter at 3.5" in the STIS data than in the ACS data. Moreover, variations are seen in (i) the visibility of the ansa(e) structures, in (ii) the relative surface brightness of the ansa(e) structures, and in (iii) the (known) intrinsic polarization of the system. These results indicate that the scattered light from the HD 163296 disk is variable. We speculate that the inner disk wall, which Sitko et al. suggests has a variable scale height as diagnosed by near-IR SED variability, induces variable self-shadowing of the outer disk. We further speculate that the observed surface brightness variability of the ansa(e) structures may indicate that the inner disk wall is azimuthally asymmetric. Subject headings: circumstellar matter - stars: individual (HD 163296) - planetary systems: formation - planetary systems: protoplanetary disks
16. Cometary grains in the HD 32297 debris disk
Science.gov (United States)
Yang, Y.-G.; Li, Aigen
2016-07-01
HD 32297 is a young A-type star with a bright edge-on debris disk. The dust thermal emission spectral energy distribution and scattered starlight spectrum are simultaneously modeled in terms of porous cometary grains. Our modeling suggests that, similar to the solar system, the debris disk around HD 32297 may have an inner warm ring and an outer cold disk which are seen in other young debris disks as well.
17. On the variability of HD 170699 - a possible COROT target
CERN Document Server
Alvarez, M; Parrao, L; Pena, J H; Machado, L Fox; Poretti, E; Martin-Ruiz, S; Amado, P; Garrido, R; Aerts, C; Csurby, Z; Paparo, M
2008-01-01
We present the analysis of the variability of HD 170699, a COROT star showing the characteristics of a non evolutionary Delta Scuti star with high rotational velocity. There is a clear period of 10.45 c/d with 5.29 mmag amplitude in the y filter. From the data, it can be seen that the star shows multi-periodicity and it is necessary to add more frequencies to adjust the observations
18. References: AePW publications
Data.gov (United States)
National Aeronautics and Space Administration — This page is the repository for the publications resulting from the AePW. This includes the special sessions at conferences: AIAA ASM 2012, Grapevine TX; AIAA SDM...
19. A Habitable Planet around HD 85512?
CERN Document Server
Kaltenegger, L; Pepe, F
2011-01-01
Aims: In this study we assess the habitability of HD85512b, a 3.6M_Earth planet orbiting a K5V star. The radial velocity data and orbital parameters for HD 85512 b have just been published, based on data from the dedicated HARPS-upgrade GTO program. Methods: This paper outlines a simple approach to evaluate habitability of rocky planets from radial velocity (RV) searches by using atmospheric models of rocky planets with H2O/CO2/N2 atmospheres, like Earth. We focus our analysis on HD 85512 b. To first order the limits of the Habitable Zone depend on the effective stellar flux distribution in wavelength and time, the planet's Bond albedo, and greenhouse gas effects in this approach. We also discuss the dependence of habitability on the measurement accuracies. Results: We provide a simple set of parameters which can be used for evaluating current and future planet candidates from RV searches for their potential habitability. We find that HD 85512 b could be potentially habitable if the planet exhibits more than ...
20. Gas lines from the 5-Myr old optically thin disk around HD141569A. Herschel observations and modeling
CERN Document Server
Thi, Wing-Fai; Pantin, Eric; Augereau, Jean-Charles; Meeus, Gwendolyn; Menard, Francois; Martin-Zaïdi, Claire; Woitke, Peter; Riviere-Marichalar, Pablo; Kamp, Inga; Carmona, Andres; Sandell, Goran; Eiroa, Carlos; Dent, Williams; Montesinos, Benjamin; Aresu, Giambattista; Meijerink, Rowin; Spaans, Marco; White, Glenn; Ardila, David; Lebreton, Jeremy; Mendigutia, Ignacio; Brittain, Sean
2013-01-01
At the distance of 99-116 pc, HD141569A is one of the nearest HerbigAe stars that is surrounded by a tenuous disk, probably in transition between a massive primordial disk and a debris disk. We observed the fine-structure lines of OI at 63 and 145 micron and the CII line at 157 micron with the PACS instrument onboard the Herschel Space Telescope as part of the open-time large programme GASPS. We complemented the atomic line observations with archival Spitzer spectroscopic and photometric continuum data, a ground-based VLT-VISIR image at 8.6 micron, and 12CO fundamental ro-vibrational and pure rotational J=3-2 observations. We simultaneously modeled the continuum emission and the line fluxes with the Monte Carlo radiative transfer code MCFOST and the thermo-chemical code ProDiMo to derive the disk gas- and dust properties assuming no dust settling. The models suggest that the oxygen lines are emitted from the inner disk around HD141569A, whereas the [CII] line emission is more extended. The CO submillimeter fl...
1. ALMA reveals the anatomy of the mm-sized dust and molecular gas in the HD 97048 disk
CERN Document Server
Walsh, Catherine; Meeus, Gwendolyn; Dent, William R F; Maud, Luke; Aikawa, Yuri; Millar, Tom J; Nomura, Hideko
2016-01-01
Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially-resolved observations at ~ mm wavelengths. We present the first spatially-resolved ~ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ~ 640 au. The ALMA data reveal a circular-symmetric dusty disk extending to ~ 350 au, and a molecular disk traced in CO J=3-2 emission, extending to ~ 750 au. The CO emission arises from a flared layer with an opening angle ~ 30 deg - 40 deg. HD 97048 is another source for which the large (~ mm-sized) dust grains are more centrally concentrated than the small (~ {\\mu}m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modelling suggests a decrement in continuum emission within ~ 50 au, consistent with the cavity size determined from mid-infrared imaging (34 +/- 4 au). The extracted continuum intensity profiles show ring-l...
2. (abstract) Airborne Emission Spectrometer (AES)
Science.gov (United States)
Beer, Reinhard
1994-01-01
AES is a low-cost analog of the TES downlooking modes. Because AES operates at ambient temperature, limb-viewing is not possible. The first flight of AES took place in April 1994 on the NASA P3B aircraft out of Wallops Island, VA. While planned as an engineering test flight, spectra were successfully acquired both over the Atlantic Ocean and the area of the Great Dismal Swamp on the Virginia-North Carolina border. At this writing (July 1994), a second series of flights on the NASA DC8 aircraft out of Ames RC,CA is in progress. By the time of the workshop, a third series using the NASA C130 should have been accomplished.
3. Formation of the resonant system HD 60532
CERN Document Server
Sandor, Zsolt
2010-01-01
Among multi-planet planetary systems there are a large fraction of resonant systems. Studying the dynamics and formation of these systems can provide valuable informations on processes taking place in protoplanetary disks where the planets are thought have been formed. The recently discovered resonant system HD 60532 is the only confirmed case, in which the central star hosts a pair of giant planets in 3:1 mean motion resonance. We intend to provide a physical scenario for the formation of HD 60532, which is consistent with the orbital solutions derived from the radial velocity measurements. Observations indicate that the system is in an antisymmetric configuration, while previous theoretical investigations indicate an asymmetric equilibrium state. The paper aims at answering this discrepancy as well. We performed two-dimensional hydrodynamical simulations of thin disks with an embedded pair of massive planets. Additionally, migration and resonant capture are studied by gravitational N-body simulations that a...
4. The Nainital–Cape Survey: A Search for Variability in Ap and Am Stars
Santosh Joshi
2005-06-01
The Nainital–Cape Survey” program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. We present here the results obtained to date. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.
5. The magnetic field of the hot spectroscopic binary HD5550
OpenAIRE
Neiner, C.; Alecian, E.; collaboration, the BinaMIcS
2015-01-01
HD5550 is a spectroscopic binary composed of two A stars observed with Narval at TBL in the frame of the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) Large Program. One component of the system is found to be an Ap star with a surprisingly weak dipolar field of ~65 G. The companion is an Am star for which no magnetic field is detected, with a detection threshold on the dipolar field of ~40 G. The system is tidally locked, the primary component is synchronised with ...
6. Kepler Observations of the Asteroseismic Binary HD 176465
CERN Document Server
White, T R; Aguirre, V Silva; Ball, W H; Bedding, T R; Chaplin, W J; Christensen-Dalsgaard, J; Garcia, R A; Gizon, L; Stello, D; Aigrain, S; Antia, H M; Appourchaux, T; Bazot, M; Campante, T L; Creevey, O L; Davies, G R; Elsworth, Y P; Gaulme, P; Handberg, R; Hekker, S; Houdek, G; Howe, R; Huber, D; Karoff, C; Marques, J P; Mathur, S; McQuillan, A; Metcalfe, T S; Mosser, B; Nielsen, M B; Régulo, C; Salabert, D; Stahn, T
2016-01-01
Binary star systems are important for understanding stellar structure and evolution, and are especially useful when oscillations can be detected and analysed with asteroseismology. However, only four systems are known in which solar-like oscillations are detected in both components. Here, we analyse the fifth such system, HD 176465, which was observed by Kepler. We carefully analysed the system's power spectrum to measure individual mode frequencies, adapting our methods where necessary to accommodate the fact that both stars oscillate in a similar frequency range. We also modelled the two stars independently by fitting stellar models to the frequencies and complementary parameters. We are able to cleanly separate the oscillation modes in both systems. The stellar models produce compatible ages and initial compositions for the stars, as is expected from their common and contemporaneous origin. Combining the individual ages, the system is about 3.0$\\pm$0.5 Gyr old. The two components of HD 176465 are young phy...
7. HD148937: a multiwavelength study of the third Galactic member of the Of?p class
CERN Document Server
Naze, Y; Rauw, G; Martins, F; Pollock, A M T; Bond, H E
2008-01-01
Three Galactic O-type stars belong to the rare class of Of?p objects: HD108, HD191612, and HD148937. The first two stars show a wealth of phenomena, including magnetic fields and strong X-ray emission, light variability, and dramatic periodic spectral variability. We present here the first detailed optical and X-ray study of the third Galactic Of?p star, HD148937. Spectroscopic monitoring has revealed low-level variability in the Balmer and HeII4686 lines, but constancy at HeI and CIII4650. The Ha line exhibits profile variations at a possible periodicity of ~7d. Model atmosphere fits yield T_{eff}=41000+-2000K, log(g)=4.0+-0.1, Mdot_{sph}1700km/s), and an order-of-magnitude overluminosity compared to normal O stars (log [L_X^unabs/L_BOL] ~ -6).
8. The SPHERE view of the planet-forming disk around HD 100546
Science.gov (United States)
Garufi, A.; Quanz, S. P.; Schmid, H. M.; Mulders, G. D.; Avenhaus, H.; Boccaletti, A.; Ginski, C.; Langlois, M.; Stolker, T.; Augereau, J.-C.; Benisty, M.; Lopez, B.; Dominik, C.; Gratton, R.; Henning, T.; Janson, M.; Ménard, F.; Meyer, M. R.; Pinte, C.; Sissa, E.; Vigan, A.; Zurlo, A.; Bazzon, A.; Buenzli, E.; Bonnefoy, M.; Brandner, W.; Chauvin, G.; Cheetham, A.; Cudel, M.; Desidera, S.; Feldt, M.; Galicher, R.; Kasper, M.; Lagrange, A.-M.; Lannier, J.; Maire, A. L.; Mesa, D.; Mouillet, D.; Peretti, S.; Perrot, C.; Salter, G.; Wildi, F.
2016-04-01
Context. The mechanisms governing planet formation are not fully understood. A new era of high-resolution imaging of protoplanetary disks has recently started, thanks to new instruments such as SPHERE, GPI, and ALMA. The planet formation process can now be directly studied by imaging both planetary companions embedded in disks and their effect on disk morphology. Aims: We image disk features that could be potential signs of planet-disk interaction with unprecedented spatial resolution and sensitivity. Two companion candidates have been claimed in the disk around the young Herbig Ae/Be star HD 100546. Thus, this object serves as an excellent target for our investigation of the natal environment of giant planets. Methods: We exploit the power of extreme adaptive optics operating in conjunction with the new high-contrast imager SPHERE to image HD 100546 in scattered light. We obtained the first polarized light observations of this source in the visible (with resolution as fine as 2 AU) and new H and K band total intensity images that we analyzed with the pynpoint package. Results: The disk shows a complex azimuthal morphology, where multiple scattering of photons most likely plays an important role. High brightness contrasts and arm-like structures are ubiquitous in the disk. A double-wing structure (partly due to angular differential imaging processing) resembles a morphology newly observed in inclined disks. Given the cavity size in the visible (11 AU), the CO emission associated to the planet candidate c might arise from within the circumstellar disk. We find an extended emission in the K band at the expected location of b. The surrounding large-scale region is the brightest in scattered light. There is no sign of any disk gap associated to b. Based on data collected at the European Southern Observatory, Chile (ESO Programs 095.C-0273(A) and 095.C-0298(A)).
9. Triggered Star Formation by Massive Stars
OpenAIRE
Lee, Hsu-Tai; Chen, W. P.
2005-01-01
We present our diagnosis of the role that massive stars play in the formation of low- and intermediate-mass stars in OB associations (the Lambda Ori region, Ori OB1, and Lac OB1 associations). We find that the classical T Tauri stars and Herbig Ae/Be stars tend to line up between luminous O stars and bright-rimmed or comet-shaped clouds; the closer to a cloud the progressively younger they are. Our positional and chronological study lends support to the validity of the radiation-driven implos...
10. Toepassing ICP-AES op het RIKILT
NARCIS (Netherlands)
Ruig, de W.G.
1980-01-01
Rapportage over de toepassing van ICP-AES op het RIKILT. Bij ICP-AES worden twee manieren van lichtemissie detectie toegepast nl. simultaan en sequentieel. De voor- en nadelen van ICP-AES t.o.v. AAS worden op een rij gezet.
11. Constraints on the Formation of the Planet Around HD188753A
CERN Document Server
Jang-Condell, H
2005-01-01
The recent discovery of a Jupiter-mass planet in the close binary star system HD188753 poses a problem for planet formation theory. A circumstellar disk around the planet's parent star would be truncated at 1.3 AU, leaving little material available for planet formation. In this paper, we attempt to model a disk around HD188753, exploring a range of parameters constrained by observations of protoplanetary disks. We find that the in situ formation of the planet around HD188753 is extremely unlikely, and that the planet must have formed before the capture of the close stellar companion.
12. Unveiling the gas and dust disk structure in HD 163296 using ALMA observations
CERN Document Server
de Gregorio-Monsalvo, I; Dent, W; Pinte, C; López, C; Klaassen, P; Hales, A; Cortés, P; Rawlings, M G; Tachihara, K; Testi, L; Takahashi, S; Chapillon, E; Mathews, G; Juhasz, A; Akiyama, E; Higuchi, A E; Saito, M; Nyman, L - Å; Phillips, N; Rodń, J; Corder, S; Van Kempen, T
2013-01-01
Aims: The aim of this work is to study the structure of the protoplanetary disk surrounding the Herbig Ae star HD 163296. Methods: We have used high-resolution and high-sensitivity ALMA observations of the CO(3-2) emission line and the continuum at 850 microns, as well as the 3- dimensional radiative transfer code MCFOST to model the data presented in this work. Results: The CO(3-2) emission unveils for the first time at sub-millimeter frequencies the vertical structure details of a gaseous disk in Keplerian rotation, showing the back- and the front-side of a flared disk. Continuum emission at 850 microns reveals a compact dust disk with a 240 AU outer radius and a surface brightness profile that shows a very steep decline at radius larger than 125 AU. The gaseous disk is more than two times larger than the dust disk, with a similar critical radius but with a shallower radial profile. Radiative transfer models of the continuum data confirms the need for a sharp outer edge to the dust disk. The models for the ...
13. Resolving the CO Snow Line in the Disk around HD 163296
CERN Document Server
Qi, Chunhua; Oberg, Karin I; Wilner, David J; Hughes, A Meredith; Andrews, Sean M; Ayala, Sandra
2011-01-01
We report Submillimeter Array (SMA) observations of CO (J=2--1, 3--2 and 6--5) and its isotopologues (13CO J=2--1, C18O J=2--1 and C17O J=3--2) in the disk around the Herbig Ae star HD 163296 at ~2" (250 AU) resolution, and interpret these data in the framework of a model that constrains the radial and vertical location of the line emission regions. First, we develop a physically self-consistent accretion disk model with an exponentially tapered edge that matches the spectral energy distribution and spatially resolved millimeter dust continuum emission. Then, we refine the vertical structure of the model using wide range of excitation conditions sampled by the CO lines, in particular the rarely observed J=6--5 transition. By fitting 13CO data in this structure, we further constrain the vertical distribution of CO to lie between a lower boundary below which CO freezes out onto dust grains (T ~ 19 K) and an upper boundary above which CO can be photodissociated (the hydrogen column density from the disk surface ...
14. Chemical Imaging of the CO Snow Line in the HD 163296 Disk
CERN Document Server
Qi, Chunhua; Andrews, Sean M; Wilner, David J; Bergin, Edwin A; Hughes, A Meredith; Hogherheijde, Michiel; D'Alessio, Paola
2015-01-01
The condensation fronts (snow lines) of H2O, CO and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density is expected to drop substantially, based solely on CO emission profiles is challenging. This has prompted an exploration of chemical signatures of CO freeze-out. We present ALMA Cycle 1 observations of the N2H+ J=3-2 and DCO+ J=4-3 emission lines toward the disk around the Herbig Ae star HD~163296 at ~0.5" (60 AU) resolution, and evaluate their utility as tracers of the CO snow line location. The N2H+ emission is distributed in a ring with an inner radius at 90 AU, corresponding to a midplane temperature of 25 K. This result is consistent with a new analysis of optically thin C18O data, which implies a sharp drop in CO abundance at 90 AU. Thus N2H+ appears to be a robust tracer of the midplane CO snow line. The DCO+ emission also has a ring morphology, but neither the inner nor the outer radi...
15. A SPATIALLY RESOLVED VERTICAL TEMPERATURE GRADIENT IN THE HD 163296 DISK
International Nuclear Information System (INIS)
We analyze sensitive, sub-arcsecond resolution ALMA science verification observations of CO emission lines in the protoplanetary disk hosted by the young, isolated Ae star HD 163296. The observed spatial morphology of the 12CO J = 3-2 emission line is asymmetric across the major axis of the disk; the 12CO J = 2-1 line features a much less pronounced, but similar, asymmetry. The J = 2-1 emission from 12CO and its main isotopologues have no resolved spatial asymmetry. We associate this behavior with the direct signature of a vertical temperature gradient and layered molecular structure in the disk. This is demonstrated using both toy models and more sophisticated calculations assuming non-local thermodynamic equilibrium conditions. A model disk structure is developed to reproduce both the distinctive spatial morphology of the 12CO J = 3-2 line as well as the J = 2-1 emission from the CO isotopologues assuming relative abundances consistent with the interstellar medium. This model disk structure has τ = 1 emitting surfaces for the 12CO emission lines that make an angle of ∼15° with respect to the disk midplane. Furthermore, we show that the spatial and spectral sensitivity of these data can distinguish between models that have sub-Keplerian gas velocities due to the vertical extent of the disk and its associated radial pressure gradient (a fractional difference in the bulk gas velocity field of ∼> 5%)
16. Structures in the protoplanetary disk of HD142527 seen in polarized scattered light
CERN Document Server
Avenhaus, Henning; Schmid, Hans Martin; Meyer, Michael R; Garufi, Antonio; Wolf, Sebastian; Dominik, Carsten
2013-01-01
We present H- and Ks-band polarized differential images (PDI) of the Herbig Ae/Be star HD142527, revealing its optically thick outer disk and the nearly empty gap. The very small inner working angle (~0.1") and high resolution achievable with an 8m-class telescope, together with a careful polarimetric calibration strategy, allow us to achieve images that surpass the quality of previous scattered light images. Previously known substructures are resolved more clearly and new structures are seen. Specifically, we are able to resolve 1) half a dozen spiral structures in the disk, including previously known outer-disk spirals as well as new spiral arms and arcs close to the inner rim of the disk; 2) peculiar holes in the polarized surface brightness at position angles of ~0{\\deg} and ~160{\\deg}; 3) the inner rim on the eastern side of the disk; 4) the gap between the outer and inner disk, ranging from the inner working angle of 0.1" out to between 0.7 and 1.0", which is nearly devoid of dust. We then use a Markov-...
17. Dynamical Stability and Habitability of a Terrestrial Planet in HD74156
Science.gov (United States)
Gino, M. C.
2003-12-01
The detection of extrasolar terrestrial planets located in the habitable regions of a star system is presently beyond our observational technologies. However, systems with multiple Jupiter-like extrasolar planets may prove to be candidates for supporting terrestrial planets provided that stable regions exist. The results of numerical integrations for the systems HD74156 and HD12661, each of which have two Jovian-type planets orbiting their parent star, demonstrates that a region exists in HD74156 where a terrestrial planet can remain in orbit on a timescale of 10\\^5 years, while HD12661 cannot support additional planets. The Swinburne Supercluster running the SWIFT computer code is used for the simulation of both massless test particles and Earth-mass planets to investigate their short-term dynamical stability. These results can be used to constrain the search region within HD74156 in which habitable terrestrial planets are most likely to be found.
18. Is the X-ray pulsating companion of HD 49798 a possible type Ia supernova progenitor?
CERN Document Server
Liu, Dong-Dong; Wu, Cheng-Yuan; Wang, Bo
2015-01-01
HD 49798 (a hydrogen depleted subdwarf O6 star) with its massive white dwarf (WD) companion has been suggested to be a progenitor candidate of type Ia supernovae (SNe Ia). However, it is still uncertain whether the companion of HD 49798 is a carbon-oxygen (CO) WD or an oxygen-neon (ONe) WD. A CO WD will explode as an SN Ia when its mass grows approach to Chandrasekhar mass, while the outcome of an accreting ONe WD is likely to be a neutron star. We followed a series of Monte Carlo binary population synthesis approach to simulate the formation of ONe WD + He star systems. We found that there is almost no orbital period as large as HD 49798 with its WD companion in these ONe WD + He star systems based on our simulations, which means that the companion of HD 49798 might not be an ONe WD. We suggest that the companion of HD 49798 is most likely a CO WD, which can be expected to increase its mass to the Chandrasekhar mass limit by accreting He-rich material from HD 49798. Thus, HD 49798 with its companion may prod...
19. Confirmation and characterization of the protoplanet HD100546 b - Direct evidence for gas giant planet formation at 50 au
CERN Document Server
Quanz, Sascha P; Meyer, Michael R; Girard, Julien H; Kenworthy, Matthew A; Kasper, Markus
2014-01-01
We present the first multi-wavelength, high-contrast imaging study confirming the protoplanet embedded in the disk around the Herbig Ae/Be star HD100546. The object is detected at L' (~3.8 micron) and M' (~4.8 micron), but not at K_s (~2.1 micron), and the emission consists of a point source component surrounded by spatially resolved emission. For the point source component we derive apparent magnitudes of L'=13.92$\\pm$0.10 mag, M'=13.33$\\pm$0.16 mag, and K_s>15.43$\\pm$0.11 mag (3-$\\sigma$ limit), and a separation and position angle of (0.457$\\pm$0.014)'' and (8.4$\\pm$1.4)$^\\circ$, and (0.472$\\pm$0.014)'' and (9.2$\\pm$1.4)$^\\circ$ in L' and M', respectively. We demonstrate that the object is co-moving with the central star and can reject any (sub-)stellar fore-/background object. Fitting a single temperature blackbody to the observed fluxes of the point source component yields an effective temperature of $T_{eff}=1028^{+227}_{-253}$ K and a radius for the emitting area of $R=6.0^{+2.5}_{-2.6}$ Jupiter radii. ...
20. Ultraviolet spectral synthesis of HD 72660
Science.gov (United States)
Golriz, S. S.; Landstreet, J. D.
2016-03-01
The study of chemical abundances in stellar atmosphere provides a useful tool to investigate the formation and evolution history of stars. The optical wavelength range has been used almost exclusively in the past to determine the elemental abundance in A-type stars. We use high-resolution, high signal-to-noise ultraviolet spectra obtained from the STIS/NUV-MAMA instrument on board Hubble Space Telescope. The spectra available cover the wavelength ranges 1630 Å-1901 Å and 2130 Å-2887 Å. The main challenge to carrying out abundance analysis in the ultraviolet is the extreme level of line blending. Abundance analysis using single isolated spectral lines is almost completely impossible; it is necessary to model spectral windows using spectrum synthesis with fairly complete line-lists. We have used the LTE spectrum synthesis code ZEEMAN to model the UV spectrum of HD 72660, adjusting abundances for a best match for elements with 6 ≤ Z≤ 82 for which lines are present in the Vinna Atomic Line Database line-list. Abundances or upper limits are derived for 32 elements. We find that except a few, our derived abundances are slightly higher than solar values. We estimate upper limits for abundances of eleven elements and abundance values of 12 elements which have not been detected in the optical. The high abundances that we find for some heavy elements may point to radiative levitation. The presence of lanthanides plus our results, suggest the reclassification of HD 72660 as a transition object between an HgMn star and an Am star.
1. Ultraviolet analysis of the peculiar supergiant HD 112374 = HR 4912
Science.gov (United States)
Bohm-Vitense, E.; Proffitt, C.
1984-01-01
The ultraviolet energy distribution of the metal-poor supergiant HD 112374 is analyzed based on observations from the International Ultraviolet Explorer (IUE) satellite for the region between 1200 and 2000 A. A discontinuity was found in the UV spectra at 2600 A which confirmed the low-abundance of heavy elements found by Luck et al. (1983). Values for effective temperature and log g in HD112374 were consistent with the star being a very luminous Population II semi-regular variable. The full observational results are presented in a table.
2. Implications of the non-detection of X-ray emission from HD 149427
CERN Document Server
Stute, Matthias
2011-01-01
HD 149427 is a very enigmatic object. It has been classified either as a planetary nebula or as a D'-type symbiotic star. Its distance is also highly uncertain. Furthermore, HD 149427 is a potential jet source. We report the non-detection of X-ray emission from HD 149427 and explore the implications to its nature. We observed the object with XMM-Newton with an effective exposure time of 33.5 ks. The upper limit for the flux of the X-ray emission in the soft band (2 keV) it is about 10^-14 erg/s/cm^2. We discuss the implication of our results in light of the possible natures of HD 149427 -- being a planetary nebula or a symbiotic star, close or very distant. The derived upper limits on the mass accretion rate of the white dwarf are untypical for symbiotic stars and may favor the picture of HD 149427 being a young PN. HD 149427 might be a symbiotic star in hibernation -- if a symbiotic star at all. We estimate the possible mass-loss rate and kinetic luminosity of the jet and find no contradiction with our upper...
3. Resolving Close Encounters: Stability in the HD 5319 and HD 7924 Planetary Systems
CERN Document Server
Kane, Stephen R
2016-01-01
Radial velocity searches for exoplanets have detected many multi-planet systems around nearby bright stars. An advantage of this technique is that it generally samples the orbit outside of inferior/superior conjunction, potentially allowing the Keplerian elements of eccentricity and argument of periastron to be well characterized. The orbital architectures for some of these systems show signs of close planetary encounters that may render the systems unstable as described. We provide an in-depth analysis of two such systems: HD 5319 and HD 7924, for which the scenario of coplanar orbits results in rapid destabilization of the systems. The poorly constrained periastron arguments of the outer planets in these systems further emphasizes the need for detailed investigations. An exhaustive scan of parameters space via dynamical simulations reveals specific mutual inclinations between the two outer planets in each system that allow for stable configurations over long timescales. We compare these configurations with ...
4. Developing A/E Capabilities
International Nuclear Information System (INIS)
During the last few years, the methods used by EMPRESARIOS AGRUPADOS and INITEC to perform Architect-Engineering work in Spain for nuclear projects has undergone a process of significant change in project management and engineering approaches. Specific practical examples of management techniques and design practices which represent a good record of results will be discussed. They are identified as areas of special interest in developing A/E capabilities for nuclear projects . Command of these areas should produce major payoffs in local participation and contribute to achieving real nuclear engineering capabities in the country. (author)
5. Chemical abundances for A-and F-type supergiant stars
CERN Document Server
Molina, R E
2016-01-01
We present the stellar parameters and elemental abundances of a set of A--F-type supergiant stars HD\\,45674, HD\\,180028, HD\\,194951 and HD\\,224893 using high resolution ($R$\\,$\\sim$\\,42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD\\,45674 and HD\\,224893. We reaffirm the abundances for HD\\,180028 and HD\\,194951 studied previously by Luck (2014) respectively. Alpha-elements indicates that objects belong to the thin disc population. From their abundances and its location on the Hertzsprung-Russell diagram seems point out that HD\\,45675, HD\\,194951 and HD\\,224893 are in the post-first dredge-up (post-1DUP) phase and they are moving in the red-blue loop region. HD~180028, on the contary, shows typical abundances of the population I but its evolutionary status could not be satisfactorily defined.
6. Chemical abundances for A-and F-type supergiant stars
Science.gov (United States)
Molina, R. E.; Rivera, H.
2016-04-01
We present the stellar parameters and elemental abundances of a set of A-F-type supergiant stars HD 45674, HD 180028, HD 194951 and HD 224893 using high resolution (R≈ 42,000) spectra taken from ELODIE library. We present the first results of the abundance analysis for HD 45674 and HD 224893. We reaffirm the abundances for HD 180028 and HD 194951 studied previously by Luck. Alpha-elements indicate that the objects belong to the thin disc population. Their abundances and their location on the Hertzsprung-Russell diagram seem to indicate that HD 45675, HD 194951 and HD 224893 are in the post-first dredge-up (post-1DUP) phase, and that they are moving in the red-blue loop region. HD 180028, on the contary, shows typical abundances of Population I, but its evolutionary status cannot be satisfactorily defined.
7. The Puzzling Spectrum of HD 94509
CERN Document Server
Cowley, C R; Hubrig, S
2015-01-01
The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. We aim to describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe I and Fe II are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmo...
8. Stability and Formation of the Resonant System HD 73526
CERN Document Server
Sándor, Z; Klagyivik, P
2007-01-01
Based on radial velocity measurements it has been found recently that the two giant planets detected around the star HD 73526 are in 2:1 resonance. However, as our numerical integration shows, the derived orbital data for this system result in chaotic behavior of the giant planets, which is uncommon among the resonant extrasolar planetary systems. We intend to present regular (non-chaotic) orbital solutions for the giant planets in the system HD 73526 and offer formation scenarios based on combining planetary migration and sudden perturbative effects such as planet-planet scattering or rapid dispersal of the protoplanetary disk. A comparison with the already studied resonant system HD 128311, exhibiting similar behavior, is also done. The new sets of orbital solutions have been derived by the Systemic Console (www.oklo.org). The stability of these solutions has been investigated by the Relative Lyapunov indicator, while the migration and scattering effects are studied by gravitational N-body simulations apply...
9. HD 285507b
DEFF Research Database (Denmark)
Quinn, Samuel N.; White, Russel J.; Latham, David W.;
2014-01-01
We report the discovery of the first hot Jupiter in the Hyades open cluster. HD 285507b orbits a V = 10.47 K4.5V dwarf (M * = 0.734 M ☉; R * = 0.656 R ☉) in a slightly eccentric () orbit with a period of days. The induced stellar radial velocity corresponds to a minimum companion mass of M Psin i...... = 0.917 ± 0.033 M Jup. Line bisector spans and stellar activity measures show no correlation with orbital phase, and the radial velocity amplitude is independent of wavelength, supporting the conclusion that the variations are caused by a planetary companion. Follow-up photometry indicates with high...
10. Biclique cryptanalysis of the full AES
DEFF Research Database (Denmark)
Bogdanov, Andrey; Khovratovich, Dmitry; Rechberger, Christian
2011-01-01
Since Rijndael was chosen as the Advanced Encryption Standard (AES), improving upon 7-round attacks on the 128-bit key variant (out of 10 rounds) or upon 8-round attacks on the 192/256-bit key variants (out of 12/14 rounds) has been one of the most difficult challenges in the cryptanalysis of block...... ciphers for more than a decade. In this paper, we present the novel technique of block cipher cryptanalysis with bicliques, which leads to the following results: The first key recovery method for the full AES-128 with computational complexity 2126.1. The first key recovery method for the full AES-192...... with computational complexity 2189.7. The first key recovery method for the full AES-256 with computational complexity 2254.4. Key recovery methods with lower complexity for the reduced-round versions of AES not considered before, including cryptanalysis of 8-round AES-128 with complexity 2124.9. Preimage search...
11. Manufacture of Automatic Heating Equipment for AES
Institute of Scientific and Technical Information of China (English)
2001-01-01
This paper introduced the design and application of automaticheating equipment for Auger Emission Spectroscopy (AES). The special electric furnace used in the AES was designed, the Al2O3 glass window which allows both visible light and infrared ray to pass through was made, and the MA2S/B thermo-meter based on infrared ray radiant energy from the sample was selected. The equipment gives dynamic analyzingby AES. It offers possibilities for widening the fields of materials surface and interface research . As a sample , the FeCr17 alloy was studied by in situ AES in the heating progress with the help of automaticheating equipment.
12. About the extrasolar multi-planet system around HD160691
CERN Document Server
Gozdziewski, K; Migaszewski, C; Gozdziewski, Krzysztof; Maciejewski, Andrzej J.; Migaszewski, Cezary
2006-01-01
We re-analyze the precision radial velocity (RV) observations of HD160691 (mu Ara) by the Anglo-Australian Planet Search Team. The star is supposed to host two Jovian companions (HD160691b, HD160691c) in long-period orbits (about 630 days and 2500 days, respectively) and a hot-Neptune (HD160691d) in about 9 days orbit. We perform a global search for the best fits in the orbital parameters space with a hybrid code employing the genetic algorithm and simplex method. The stability of Keplerian fits is verified with the N-body model of the RV signal that takes into account the dynamical constraints (so called GAMP method). Our analysis reveals a signature of the fourth, yet unknown and unconfirmed, 0.5 Jupiter-mass planet in about 307 days orbit. In overview, the global architecture of the four-planet configuration recalls the Solar system. All companions of HD160691 move in close to circular orbits. The orbits of the two inner Jovian planets are close to the 2:1 mean motion resonance (MMR). The alternative three...
13. Chromosome isolation by flow sorting in Aegilops umbellulata and Ae. comosa and their allotetraploid hybrids Ae. biuncialis and Ae. geniculata.
Directory of Open Access Journals (Sweden)
István Molnár
Full Text Available This study evaluates the potential of flow cytometry for chromosome sorting in two wild diploid wheats Aegilops umbellulata and Ae. comosa and their natural allotetraploid hybrids Ae. biuncialis and Ae. geniculata. Flow karyotypes obtained after the analysis of DAPI-stained chromosomes were characterized and content of chromosome peaks was determined. Peaks of chromosome 1U could be discriminated in flow karyotypes of Ae. umbellulata and Ae. biuncialis and the chromosome could be sorted with purities exceeding 95%. The remaining chromosomes formed composite peaks and could be sorted in groups of two to four. Twenty four wheat SSR markers were tested for their position on chromosomes of Ae. umbellulata and Ae. comosa using PCR on DNA amplified from flow-sorted chromosomes and genomic DNA of wheat-Ae. geniculata addition lines, respectively. Six SSR markers were located on particular Aegilops chromosomes using sorted chromosomes, thus confirming the usefulness of this approach for physical mapping. The SSR markers are suitable for marker assisted selection of wheat-Aegilops introgression lines. The results obtained in this work provide new opportunities for dissecting genomes of wild relatives of wheat with the aim to assist in alien gene transfer and discovery of novel genes for wheat improvement.
14. The far-infrared behaviour of Herbig Ae/Be discs: Herschel PACS photometry
CERN Document Server
Pascual, N; Meeus, G; Marshall, J P; Mendigutía, I; Sandell, G
2016-01-01
Herbig Ae/Be objects are pre-main sequence stars surrounded by gas- and dust-rich circumstellar discs. These objects are in the throes of star and planet formation, and their characterisation informs us of the processes and outcomes of planet formation processes around intermediate mass stars. Here we analyse the spectral energy distributions of disc host stars observed by the Herschel Open Time Key Programme Gas in Protoplanetary Systems'. We present Herschel/PACS far-infrared imaging observations of 22 Herbig Ae/Bes and 5 debris discs, combined with ancillary photometry spanning ultraviolet to sub-millimetre wavelengths. From these measurements we determine the diagnostics of disc evolution, along with the total excess, in three regimes spanning near-, mid-, and far-infrared wavelengths. Using appropriate statistical tests, these diagnostics are examined for correlations. We find that the far-infrared flux, where the disc becomes optically thin, is correlated with the millimetre flux, which provides a meas...
15. The Discovery of HD 37605c and a Dispositive Null Detection of Transits of HD 37605b
DEFF Research Database (Denmark)
Xuesong Wang, Sharon; Wright, Jason T.; Cochran, William;
2012-01-01
We report the radial-velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P~55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of ~7.5 years with a low eccentricity and an Msini of ~3.4 MJup. Our...... discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS) effort to provide precise ephemerides to long-period planets for transit follow......-up. With a total of 137 radial velocity observations covering almost eight years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using...
16. Low-amplitude and long-period radial velocity variations in giants HD 3574, 63 Cygni, and HD 216946 (Research Note)
CERN Document Server
Lee, B -C; Park, M -G; Hatzes, A P; Kim, K -M
2014-01-01
Aims. We study the low-amplitude and long-period variations in evolved stars using precise radial velocity measurements. Methods. The high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) was used from September 2004 to May 2014 as part of the exoplanet search program at the Bohyunsan Optical Astronomy Observatory (BOAO). Results. We report the detection of low-amplitude and long-period orbital radial velocity variations in three evolved stars, HD 3574, 63 Cyg, and HD 216946. They have periods of 1061, 982, and 1382 days and semi-amplitudes of 376, 742, and 699 m/s, respectively.
17. ALE: AES-based lightweight authenticated encryption
DEFF Research Database (Denmark)
Bogdanov, Andrey; Mendel, Florian; Regazzoni, Francesco;
2014-01-01
In this paper, we propose a new Authenticated Lightweight Encryption algorithm coined ALE. The basic operation of ALE is the AES round transformation and the AES-128 key schedule. ALE is an online single-pass authenticated encryption algorithm that supports optional associated data. Its security...... relies on using nonces. We provide an optimized low-area implementation of ALE in ASIC hardware and demonstrate that its area is about 2.5 kGE which is almost two times smaller than that of the lightweight implementations for AES-OCB and ASC-1 using the same lightweight AES engine. At the same time......, it is at least 2.5 times more performant than the alternatives in their smallest implementations by requiring only about 4 AES rounds to both encrypt and authenticate a 128-bit data block for longer messages. When using the AES-NI instructions, ALE outperforms AES-GCM, AES-CCM and ASC-1 by a considerable margin...
18. Searching for stable orbits in the HD 10180 planetary system
Directory of Open Access Journals (Sweden)
2011-02-01
Full Text Available A planetary system with at least seven planets has been found around the star HD 10180. However, the traditional Keplerian and n-body fits to the data provide an orbital solution that becomes unstable very quickly, which may quest the reliability of the observations. Here we show that stable orbital configurations can be obtained if general relativity and long-term dissipation raised by tides on the innermost planet are taken into account.
19. B- and A-Type Stars in the Taurus-Auriga Star-Forming Region
Science.gov (United States)
Mooley, Kunal; Hillenbrand, Lynne; Rebull, Luisa; Padgett, Deborah; Knapp, Gillian
2013-01-01
We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud, (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey, and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region. We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), t Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.
20. Waters, dust evolution in protoplanetary disks around herbig ae/be stars—the spitzer view
NARCIS (Netherlands)
Juhász, A.; Bouwman, J.; Henning, Th.; Acke, B.; Van Den Ancker, M.; Meeus, G.; Dominik, C.; Min, M.; Tielens, A. G. G. M.; Waters, L.B.F.M.
2010-01-01
In this paper, we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validi
1. Dust evolution in protoplanetary disks around Herbig Ae/Be stars—the Spitzer view
NARCIS (Netherlands)
A. Juhász; J. Bouwman; T. Henning; B. Acke; M.E. van den Ancker; G. Meeus; C. Dominik; M. Min; A.G.G.M. Tielens; L.B.F.M. Waters
2010-01-01
In this paper, we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validi
2. AES in deficit on Georgian trade
International Nuclear Information System (INIS)
According to Vedomosti journal Russian state energy company RAO JES Rossii paid for Georgian assets acquisition to American company AES only 23 million USD, what is less than a tenth of sum which AES had originally paid for it. Thus total transaction value including debts reached 80 millions USD. But internal documents of American AES confirm that Americans paid 260 millions USD for Georgian assets and they took besides over 60 millions USD of obligations. Russians bought Georgian AES assets through Finnish filial Nordic Oy. Thus they obtained 75 per cent share in Telasi company which operates distributive network in Tbilisi, two blocks of plant in Tbilisi and half share in AES-Transenergy company which exports electric energy from Georgia to Turkey. RAO JES besides got managerial laws on Hramesi company which owns two water plants. Russian company controls one fifth of production and 35 per cent of electric energy sale in Georgia by these assets
3. The SOPHIE search for northern extrasolar planets II. A multiple planet system around HD 9446
OpenAIRE
Hebrard, G.; Bonfils, X.; Segransan, D.; Moutou, C.; Delfosse, X.; Bouchy, F.; Boisse, I.; Arnold, L; Desort, M.; Diaz, R. F.; Eggenberger, A.; Ehrenreich, D.; Forveille, T.; Lagrange, A.-M.; Lovis, C.
2010-01-01
We report the discovery of a planetary system around HD9446, performed from radial velocity measurements secured with the spectrograph SOPHIE at the 193-cm telescope of the Haute-Provence Observatory during more than two years. At least two planets orbit this G5V, active star: HD9446b has a minimum mass of 0.7 M_Jup and a slightly eccentric orbit with a period of 30 days, whereas HD9446c has a minimum mass of 1.8 M_Jup and a circular orbit with a period of 193 days. As for most of the known m...
4. HD 209621: Abundances of neutron-capture elements
OpenAIRE
Goswami, Aruna; Aoki, Wako
2010-01-01
High resolution spectra obtained from the Subaru Telescope High Dispersion Spectrograph have been used to update the stellar atmospheric parameters and metallicity of the star HD 209621. We have derived a metallicity of [Fe/H] = -1.93 for this star, and have found a large enhancement of carbon and of heavy elements, with respect to iron. Updates on the elemental abundances of four s-process elements (Y, Ce, Pr, Nd) along with the first estimates of abundances for a number of other heavy eleme...
5. Determining the midplane conditions of circumstellar discs using gas and dust modelling: a study of HD 163296
CERN Document Server
Boneberg, Dominika M; Haworth, Thomas J; Clarke, Cathie J; Min, Michiel
2016-01-01
The mass of gas in protoplanetary discs is a quantity of great interest for assessing their planet formation potential. Disc gas masses are however traditionally inferred from measured dust masses by applying an assumed standard gas to dust ratio of $g/d=100$. Furthermore, measuring gas masses based on CO observations has been hindered by the effects of CO freeze-out. Here we present a novel approach to study the midplane gas by combining C$^{18}$O line modelling, CO snowline observations and the spectral energy distribution (SED) and selectively study the inner tens of au where freeze-out is not relevant. We apply the modelling technique to the disc around the Herbig Ae star HD 163296 with particular focus on the regions within the CO snowline radius, measured to be at 90 au in this disc. Our models yield the mass of C$^{18}$O in this inner disc region of $M_{\\text{C}^{18}\\text{O}}(<90\\,\\text{au})\\sim 2\\times10^{-8}$ M$_\\odot$. We find that most of our models yield a notably low $g/d<20$, especially in...
6. Determining the mid-plane conditions of circumstellar discs using gas and dust modelling: a study of HD 163296
Science.gov (United States)
Boneberg, Dominika M.; Panić, Olja; Haworth, Thomas J.; Clarke, Cathie J.; Min, Michiel
2016-09-01
The mass of gas in protoplanetary discs is a quantity of great interest for assessing their planet formation potential. Disc gas masses are, however, traditionally inferred from measured dust masses by applying an assumed standard gas-to-dust ratio of g/d = 100. Furthermore, measuring gas masses based on CO observations has been hindered by the effects of CO freeze-out. Here we present a novel approach to study the mid-plane gas by combining C18O line modelling, CO snowline observations and the spectral energy distribution and selectively study the inner tens of au where freeze-out is not relevant. We apply the modelling technique to the disc around the Herbig Ae star HD 163296 with particular focus on the regions within the CO snowline radius, measured to be at 90 au in this disc. Our models yield the mass of C18O in this inner disc region of M_{C^{18}O}({dust masses in discs within the CO snowline location without making assumptions about the gas-to-dust ratio.
7. Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE
CERN Document Server
Ginski, C; Pinilla, P; Dominik, C; Boccaletti, A; de Boer, J; Benisty, M; Biller, B; Feldt, M; Garufi, A; Keller, C U; Kenworthy, M; Maire, A L; Ménard, F; Mesa, D; Milli, J; Min, M; Pinte, C; Quanz, S P; van Boekel, R; Bonnefoy, M; Chauvin, G; Desidera, S; Gratton, R; Girard, J H V; Keppler, M; Kopytova, T; Lagrange, A -M; Langlois, M; Rouan, D; Vigan, A
2016-01-01
We studied the well known circumstellar disk around the Herbig Ae/Be star HD 97048 with high angular resolution to reveal undetected structures in the disk, which may be indicative of disk evolutionary processes such as planet formation. We used the IRDIS near-IR subsystem of the extreme adaptive optics imager SPHERE at the ESO/VLT to study the scattered light from the circumstellar disk via high resolution polarimetry and angular differential imaging. We imaged the disk in unprecedented detail and revealed four ring-like brightness enhancements and corresponding gaps in the scattered light from the disk surface with radii between 39 au and 341 au. We derived the inclination and position angle as well as the height of the scattering surface of the disk from our observational data. We found that the surface height profile can be described by a single power law up to a separation ~270 au. Using the surface height profile we measured the scattering phase function of the disk and found that it is well consistent ...
8. The magnetic field of the hot spectroscopic binary HD 5550
Science.gov (United States)
Neiner, C.; Alecian, E.
2015-12-01
HD 5550 is a spectroscopic binary composed of two A stars observed with Narval at TBL in the frame of the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) Large Program. One component of the system is found to be an Ap star with a surprisingly weak dipolar field of ˜65 G. The companion is an Am star for which no magnetic field is detected, with a detection threshold on the dipolar field of ˜40 G. The system is tidally locked, the primary component is synchronised with the orbit, but the system is probably not completely circularised yet. This work is only the second detailed study of magnetic fields in a hot short-period spectroscopic binary. More systems are currently being observed with both Narval at TBL and ESPaDOnS at CFHT within the BinaMIcS project, with the goal of understanding how magnetism can impact binary evolution and vice versa.
9. The magnetic field of the hot spectroscopic binary HD5550
CERN Document Server
Neiner, C
2015-01-01
HD5550 is a spectroscopic binary composed of two A stars observed with Narval at TBL in the frame of the BinaMIcS (Binarity and Magnetic Interactions in various classes of Stars) Large Program. One component of the system is found to be an Ap star with a surprisingly weak dipolar field of ~65 G. The companion is an Am star for which no magnetic field is detected, with a detection threshold on the dipolar field of ~40 G. The system is tidally locked, the primary component is synchronised with the orbit, but the system is probably not completely circularised yet. This work is only the second detailed study of magnetic fields in a hot short-period spectroscopic binary. More systems are currently being observed with both Narval at TBL and ESPaDOnS at CFHT within the BinaMIcS project, with the goal of understanding how magnetism can impact binary evolution and vice versa.
10. Spectroscopic Binaries near the North Galactic Pole Paper 24: HD 106104, 109281, 109463 and 110743
R. F. Griffin
2001-06-01
The four stars treated in this paper have been under observation with photoelectric radial-velocity spectrometers for many years. They have proved to be binaries with periods of 30, 1828, 1514 and 822 days respectively; the orbits are of modest eccentricity apart from that of HD 110743 which is indistinguishable from a circle. The mass functions are small, and no companion has been observed for any of the stars. HD 110743, a K dwarf, is much the nearest of the four, and its orbit is of short enough period for the photocentric motion to have been recognized by Hipparcos. An eleventh-magnitude star rather more than 1' away from HD 106104 is shown to be a genuine physical companion, with practically identical radial velocity, proper motion and distance modulus, although the projected separation is about 13,000 AU.
11. Attacks and countermeasures on AES and ECC
DEFF Research Database (Denmark)
Tange, Henrik; Andersen, Birger
2013-01-01
AES (Advanced Encryption Standard) is widely used in LTE and Wi-Fi communication systems. AES has recently been exposed to new attacks which have questioned the overall security of AES. The newest attack is a so called biclique attack, which is using the fact that the content of the state array...... is foreseeable while the rounds are performed. ECC (Elliptic Curve Cryptography) is used as a public key crypto system with the key purpose of creating a private shared between two participants in a communication network. Attacks on ECC include the Pohlig-Hellman attack and the Pollard's rho attack. Furthermore...
12. Spectroscopic variability of two Oe stars
CERN Document Server
Rauw, G; Naze, Y; Eversberg, T; Alves, F; Arnold, W; Bergmann, T; Viegas, N G Correia; Fahed, R; Fernando, A; Gonzalez-Perez, J N; Carreira, L F Gouveia; Hempelmann, A; Hunger, T; Knapen, J H; Leadbeater, R; Dias, F Marques; Mittag, M; Moffat, A F J; Reinecke, N; Ribeiro, J; Romeo, N; Gallego, J Sanchez; Santos, E M Dos; Schanne, L; Schmitt, J H M M; Schroeder, K -P; Stahl, O; Stober, Ba; Stober, Be; Vollmann, K
2015-01-01
The Oe stars HD45314 and HD60848 have recently been found to exhibit very different X-ray properties: whilst HD60848 has an X-ray spectrum and emission level typical of most OB stars, HD45314 features a much harder and brighter X-ray emission, making it a so-called gamma Cas analogue. Monitoring the optical spectra could provide hints towards the origin of these very different behaviours. We analyse a large set of spectroscopic observations of HD45314 and HD60848, extending over 20 years. We further attempt to fit the H-alpha line profiles of both stars with a simple model of emission line formation in a Keplerian disk. Strong variations in the strengths of the H-alpha, H-beta, and He I 5876 emission lines are observed for both stars. In the case of HD60848, we find a time lag between the variations in the equivalent widths of these lines. The emission lines are double peaked with nearly identical strengths of the violet and red peaks. The H-alpha profile of this star can be successfully reproduced by our mod...
13. New related-key rectangle attacks on reduced AES-192 and AES-256
Institute of Scientific and Technical Information of China (English)
WEI YongZhuang; HU YuPu
2009-01-01
In this paper, we examine the security of reduced AES-192 and AES-256 against related-key rectangle attacks by exploiting the weakness in the AES key schedule. We find the following two new attacks: 9-round reduced AES-192 with 4 related keys, and 10-round reduced AES-256 with 4 related keys. Our results show that related-key rectangle attack with 4 related keys on 9-round reduced AES-192 requires a data complexity of about 2101 chosen plaintexts and a time complexity of about 2174.8 encryptions, and moreover, related-key rectangle attack with 4 related keys on 10-round reduced AES-256 requires a data complexity of about 297.5 chosen plaintexts and a time complexity of about 2254 encryptions. These attacks are the first known attacks on 9-round reduced AES-192 and 10-round reduced AES-256 with only 4 related keys. Furthermore, we give an improvement of the 10-round reduced AES-192 attack presented at FSE2007, which reduces both the data complexity and the time complexity.
14. HD depletion in starless cores
CERN Document Server
Sipilä, O; Harju, J
2013-01-01
Aims: We aim to investigate the abundances of light deuterium-bearing species such as HD, H2D+ and D2H+ in a gas-grain chemical model including an extensive description of deuterium and spin state chemistry, in physical conditions appropriate to the very centers of starless cores. Methods: We combine a gas-grain chemical model with radiative transfer calculations to simulate density and temperature structure in starless cores. The chemical model includes deuterated forms of species with up to 4 atoms and the spin states of the light species H2, H2+ and H3+ and their deuterated forms. Results: We find that HD eventually depletes from the gas phase because deuterium is efficiently incorporated to grain-surface HDO, resulting in inefficient HD production on grains. HD depletion has consequences not only on the abundances of e.g. H2D+ and D2H+, whose production depends on the abundance of HD, but also on the spin state abundance ratios of the various light species, when compared with the complete depletion model ...
15. Discovery of new roAp pulsators in the UVES survey of cool magnetic Ap stars
CERN Document Server
Kochukhov, O; Ryabchikova, T; Boyko, S; Cunha, M; Tsymbal, V; Weiss, W
2013-01-01
We have carried out a survey of short-period pulsations among a sample of carefully chosen cool Ap stars using time-resolved observations with the UVES spectrometer at the ESO 8-m VLT telescope. Here we report the discovery of pulsations with amplitudes 50-100 m/s and periods 7-12 min in HD132205, HD148593 and HD151860. These objects are therefore established as new rapidly oscillating Ap (roAp) stars. In addition, we independently confirm the presence of pulsations in HD69013, HD96237 and HD143487 and detect, for the first time, radial velocity oscillations in two previously known photometric roAp stars HD119027 and HD185256. At the same time, no pulsation variability is found for HD5823, HD178892 and HD185204. All of the newly discovered roAp stars were previously classified as non-pulsating based on the low-precision ground-based photometric surveys. This shows that such observations cannot be used to reliably distinguish between pulsating and non-pulsating stars and that all cool Ap stars may harbor p-mod...
16. HD 80606: searching for the chemical signature of planet formation
Science.gov (United States)
Saffe, C.; Flores, M.; Buccino, A.
2015-10-01
Context. Binary systems with similar components are ideal laboratories that allow several physical processes to be tested, such as the possible chemical pattern imprinted by the planet formation process. Aims: We explore the probable chemical signature of planet formation in the remarkable binary system HD 80606-HD 80607. The star HD 80606 hosts a giant planet with ~4 MJup detected by both transit and radial velocity techniques, which is one of the most eccentric planets detected to date. We study condensation temperature Tc trends of volatile and refractory element abundances to determine whether there is a depletion of refractories, which could be related to the terrestrial planet formation. Methods: We carried out a high-precision abundance determination in both components of the binary system via a line-by-line, strictly differential approach. First, we used the Sun as a reference and then we used HD 80606. The stellar parameters Teff, log g, [Fe/H] and vturb were determined by imposing differential ionization and excitation equilibrium of Fe I and Fe II lines, with an updated version of the program FUNDPAR, together with plane-parallel local thermodynamic equilibrium (LTE) ATLAS9 model atmospheres and the MOOG code. Then, we derived detailed abundances of 24 different species with equivalent widths and spectral synthesis with the program MOOG. The chemical patterns were compared with the solar-twins Tc trends of Meléndez et al. (2009, AJ, 704, L66) and with a sample of solar-analogue stars with [Fe/H] ~ +0.2 dex from Neves et al. (2009, A&A, 497, 563). The Tc trends were also compared mutually between both stars of the binary system. Results: From the study of Tc trends, we concluded that the stars HD 80606 and HD 80607 do not seem to be depleted in refractory elements, which is different for the case of the Sun. Then, following the interpretation of Meléndez et al. (2009), the terrestrial planet formation would have been less efficient in the components of
17. Calculating Auroral Oval Pattern by AE Index
Institute of Scientific and Technical Information of China (English)
CHEN Anqin; LI Jiawei; YANG Guanglin; WANG Jingsong
2008-01-01
The relationship between the auroral oval pattern, i.e., location, size, shape, and intensity, and the auroral electrojet activity index (AE index) is studied. It is found that the maximal auroral intensity is elliptically distributed, and the lengths of semimajor and semiminor axes are positively correlated to AE.The intensity along the normal of the auroral oval can be satisfyingly described by a Gaussian distribution,and the maximum and the full width at half maximum of the Gaussian distribution are both positively correlated to AE. Based on these statistical results, a series of experimental formulas as a function of AE are developed to calculate the location, size, shape, and intensity of the auroral oval. These formulas are validated by the auroral images released by SWPC/NOAA.
18. The Spectrum of HD 3651B: An Extrasolar Nemesis?
CERN Document Server
Burgasser, A J
2006-01-01
I present detailed analysis of the near-infrared spectrum of HD 3651B, a faint, co-moving wide companion to the nearby planet-hosting star HD 3651. The presence of strong H_2O and CH_4 absorption bands confirm this source as a late T-type brown dwarf with spectral type T8. Application of the technique of Burgasser, Burrows & Kirkpatrick yields T_eff = 840+/-80 K, log(g) = 4.9+/-0.2, M = 30+/-10 M_Jup and an age in the range 0.7-3.4 Gyr, making HD 3651B a slightly warmer analog to the field T8 2MASS 0415-0935. The derived age for this companion is somewhat better constrained than estimates for its primary, which ranges from ~2 Gyr to >12 Gyr. As a widely orbiting massive object to a known planetary system that could potentially harbor terrestrial planets in its habitable zone, HD 3651B may play the role of Nemesis in this system.
19. New Encryption Standard AES%一种新的加密标准 AES
Institute of Scientific and Technical Information of China (English)
单玉峰; 潘孟贤
2002-01-01
AES是一种新的加密标准,它是分组加密算法,分组长度为128位,密钥长度为128bits、192bits、256bits三种,分别称为AES-128、AES-192、AES-256.本文介绍了AES的加密算法的加密过程,函数定义,密钥扩展过程.
20. Planetary companions orbiting M giants HD 208527 and HD 220074
CERN Document Server
Lee, B -C; Park, M -G
2012-01-01
Aims. The purpose of the present study is to research the origin of planetary companions by using a precise radial velocity (RV) survey. Methods. The high-resolution spectroscopy of the fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO) is used from September 2008 to June 2012. Results. We report the detection of two exoplanets in orbit around HD 208527 and HD 220074 exhibiting periodic variations in RV of 875.5 +/- 5.8 and 672.1 +/- 3.7 days. The RV variations are not apparently related to the surface inhomogeneities and a Keplerian motion of the planetary companion is the most likely explanation. Assuming possible stellar masses of 1.6 +/- 0.4 and 1.2 +/- 0.3 M_Sun, we obtain the minimum masses for the exoplanets of 9.9 +/- 1.7 and 11.1 +/- 1.8 M_Jup around HD 208527 and HD 220074 with an orbital semi-major axis of 2.1 +/- 0.2 and 1.6 +/- 0.1 AU and an eccentricity of 0.08 and 0.14, respectively. We also find that the previously known spectral class...
1. THE DISCOVERY OF HD 37605c AND A DISPOSITIVE NULL DETECTION OF TRANSITS OF HD 37605b
Energy Technology Data Exchange (ETDEWEB)
Wang, Sharon Xuesong; Wright, Jason T.; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 (United States); Cochran, William; Endl, Michael; MacQueen, Phillip J. [McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Kane, Stephen R.; Von Braun, Kaspar [NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Henry, Gregory W. [Center of Excellence in Information Systems, Tennessee State University, 3500 John A. Merritt Boulevard, Box 9501, Nashville, TN 37209 (United States); Payne, Matthew J.; Ford, Eric B. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Antoci, Victoria; Dragomir, Diana; Matthews, Jaymie M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T1Z1 (Canada); Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard, E-mail: xxw131@psu.edu, E-mail: jtwright@astro.psu.edu [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)
2012-12-10
We report the radial velocity discovery of a second planetary mass companion to the K0 V star HD 37605, which was already known to host an eccentric, P {approx} 55 days Jovian planet, HD 37605b. This second planet, HD 37605c, has a period of {approx}7.5 years with a low eccentricity and an Msin i of {approx}3.4 M{sub Jup}. Our discovery was made with the nearly 8 years of radial velocity follow-up at the Hobby-Eberly Telescope and Keck Observatory, including observations made as part of the Transit Ephemeris Refinement and Monitoring Survey effort to provide precise ephemerides to long-period planets for transit follow-up. With a total of 137 radial velocity observations covering almost 8 years, we provide a good orbital solution of the HD 37605 system, and a precise transit ephemeris for HD 37605b. Our dynamic analysis reveals very minimal planet-planet interaction and an insignificant transit time variation. Using the predicted ephemeris, we performed a transit search for HD 37605b with the photometric data taken by the T12 0.8 m Automatic Photoelectric Telescope (APT) and the MOST satellite. Though the APT photometry did not capture the transit window, it characterized the stellar activity of HD 37605, which is consistent of it being an old, inactive star, with a tentative rotation period of 57.67 days. The MOST photometry enabled us to report a dispositive null detection of a non-grazing transit for this planet. Within the predicted transit window, we exclude an edge-on predicted depth of 1.9% at the >>10{sigma} level, and exclude any transit with an impact parameter b > 0.951 at greater than 5{sigma}. We present the BOOTTRAN package for calculating Keplerian orbital parameter uncertainties via bootstrapping. We made a comparison and found consistency between our orbital fit parameters calculated by the RVLIN package and error bars by BOOTTRAN with those produced by a Bayesian analysis using MCMC.
2. A Herschel view of IC 1396 A: Unveiling the different sequences of star formation
CERN Document Server
Sicilia-Aguilar, Aurora; Getman, Konstantin; Henning, Thomas; Merin, Bruno; Eiroa, Carlos; Riviere-Marichalar, Pablo; Currie, Thayne
2013-01-01
The IC1396A globule in the young cluster Tr37, hosting many young stars and protostars, is assumed to be a site of triggered star formation. We mapped IC1396A with Herschel/PACS at 70 and 160 micron. The Herschel maps trace in great detail the very embedded protostellar objects and the structure of the cloud. PACS data reveal a previously unknown Class 0 object (IC1396A-PACS-1) located behind the ionization front. IC1396A-PACS-1 is not detectable with Spitzer, but shows marginal X-ray emission. The data also allowed to study three of the Class I intermediate-mass objects within the cloud. We derived approximate cloud temperatures to study the effect and potential interactions between the protostars and the cloud. The Class 0 object is associated with the densest and colder part of IC1396A. Heating in the cloud is dominated by the winds and radiation of the O6.5 star HD 206267 and, to a lesser extent, by the effects of the Herbig Ae star V 390 Cep. The surroundings of the Class I and Class II objects embedded ...
3. The Influence of Mass Loss on the Eccentricity of Double Star Orbits
Science.gov (United States)
Docobo, J. A.; Prieto, C.; Ling, J. F.
In this comunication we study the behaviour of the eccentricity of double star orbits (visual and wide spectroscopic binaries) according to simplified laws of mass loss. Applications to the systems WDS 05245S0224 - HD 35411, WDS 05387S0236 - HD 37468 and WDS 06154S0902 - HD 43362 are included.
4. Three-dimensional orbit and physical parameters of HD 6840
International Nuclear Information System (INIS)
HD 6840 is a double-lined visual binary with an orbital period of ∼7.5 years. By fitting the speckle interferometric measurements made by the 6 m BTA telescope and 3.5 m WIYN telescope, Balega et al. gave a preliminary astrometric orbital solution of the system in 2006. Recently, Griffin derived a precise spectroscopic orbital solution from radial velocities observed with OPH and Cambridge Coravel. However, due to the low precision of the determined orbital inclination, the derived component masses are not satisfying. By adding the newly collected astrometric data in the Fourth Catalog of Interferometric Measurements of Binary Stars, we give a three-dimensional orbit solution with high precision and derive the preliminary physical parameters of HD 6840 via a simultaneous fit including both astrometric and radial velocity measurements. (paper)
5. Modelling the Corona of HD 189733 in 3D
CERN Document Server
Strugarek, Antoine; Matt, Sean P; Réville, Victor; Donati, Jean-François; Moutou, Claire; Fares, Rim
2014-01-01
The braking of main sequence stars originates mainly from their stellar wind. The efficiency of this angular momentum extraction depends on the rotation rate of the star, the acceleration profile of the wind and the coronal magnetic field. The derivation of scaling laws parametrizing the stellar wind torque is important for our understanding of gyro-chronology and the evolution of the rotation rates of stars. In order to understand the impact of complex magnetic topologies on the stellar wind torque, we present three- dimensional, dynamical simulations of the corona of HD 189733. Using the observed complex topology of the magnetic field, we estimate how the torque associated with the wind scales with model parameters and compare those trends to previously published scaling laws.
6. Clinical epidemiology of human AE in Europe.
Science.gov (United States)
Vuitton, D A; Demonmerot, F; Knapp, J; Richou, C; Grenouillet, F; Chauchet, A; Vuitton, L; Bresson-Hadni, S; Millon, L
2015-10-30
This review gives a critical update of the situation regarding alveolar echinococcosis (AE) in Europe in humans, based on existing publications and on findings of national and European surveillance systems. All sources point to an increase in human cases of AE in the "historic endemic areas" of Europe, namely Germany, Switzerland, Austria and France and to the emergence of human cases in countries where the disease had never been recognised until the end of the 20th century, especially in central-eastern and Baltic countries. Both increase and emergence could be only due to methodological biases; this point is discussed in the review. One explanation may be given by changes in the animal reservoir of the parasite, Echinococcus multilocularis (increase in the global population of foxes in Europe and its urbanisation, as well as a possible increased involvement of pet animals as definitive infectious hosts). The review also focuses onto 2 more original approaches: (1) how changes in therapeutic attitudes toward malignant and chronic inflammatory diseases may affect the epidemiology of AE in the future in Europe, since a recent survey of such cases in France showed the emergence of AE in patients with immune suppression since the beginning of the 21st century; (2) how setting a network of referral centres in Europe based on common studies on the care management of patients might contribute to a better knowledge of AE epidemiology in the future. PMID:26346900
7. 22 CFR 120.30 - The Automated Export System (AES).
Science.gov (United States)
2010-04-01
... 22 Foreign Relations 1 2010-04-01 2010-04-01 false The Automated Export System (AES). 120.30... DEFINITIONS § 120.30 The Automated Export System (AES). The Automated Export System (AES) is the Department of Commerce, Bureau of Census, electronic filing of export information. The AES shall serve as the...
8. HD 16771: A lithium-rich giant in the red-clump stage
Science.gov (United States)
Reddy, Arumalla B. S.; Lambert, David L.
2016-05-01
Aims: We report the discovery of a young lithium rich giant, HD 16771, in the core-helium burning phase that does not seem to fit existing proposals of Li synthesis near the luminosity function bump or during He-core flash. We aim to understand the nature of Li enrichment in the atmosphere of HD 16771 by exploring various Li enhancement scenarios. Methods: We have collected high-resolution echelle spectra of HD 16771 and derived stellar parameters and chemical abundances for 27 elements by either line equivalent widths or synthetic spectrum analyses. Results: HD 16771 is a Li-rich (log ɛ(Li) = + 2.67 ± 0.10 dex) intermediate mass giant star (M = 2.4 ± 0.1 M⊙) with age ~ 0.76 ± 0.13 Gyr and located at the red giant clump. Kinematics and chemical compositions are consistent with HD 16771 being a member of the Galactic thin disk population. The non-detection of 6Li (<3%), a low carbon isotopic ratio (12C/13C = 12 ± 2), and the slow rotation (vsin i = 2.8 km s-1) all suggest that lithium might have been synthesized in this star. On the contrary, HD 16771 with a mass of 2.4 M⊙ has no chance of encountering luminosity function bump and He-core flash where the possibility of fast deep-mixing for Li enrichment in K giants has been suggested previously. Conclusions: Based of the evolutionary status of this star, we discuss the possibility that 7Li synthesis in HD 16771 is triggered by the engulfment of close-in planet(s) during the RGB phase.
9. AES ALGORITHM IMPLEMENTATION IN PROGRAMMING LANGUAGES
Directory of Open Access Journals (Sweden)
Luminiţa DEFTA
2010-12-01
Full Text Available Information encryption represents the usage of an algorithm to convert an unknown message into an encrypted one. It is used to protect the data against unauthorized access. Protected data can be stored on a media device or can be transmitted through the network. In this paper we describe a concrete implementation of the AES algorithm in the Java programming language (available from Java Development Kit 6 libraries and C (using the OpenSSL library. AES (Advanced Encryption Standard is an asymmetric key encryption algorithm formally adopted by the U.S. government and was elected after a long process of standardization.
10. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633
Science.gov (United States)
Mikulášek, Zdeněk; Paunzen, Ernst; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hümmerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janík, Jan; Jagelka, Miroslav
2016-07-01
We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.
11. Fine detrending of raw Kepler and MOST photometric data of KIC 6950556 and HD 37633
CERN Document Server
Mikulasek, Zdenek; Zejda, Miloslav; Semenko, Evgenij; Bernhard, Klaus; Hummerich, Stefan; Zhang, Jia; Hubrig, Swetlana; Kuschnig, Rainer; Janik, Jan; Jagelka, Miroslav
2016-01-01
We present a simple phenomenological method for detrending of raw Kepler and MOST photometry, which is illustrated by means of photometric data processing of two periodically variable chemically peculiar stars, KIC 6950556 and HD 37633. In principle, this method may be applied to any type of periodically variable objects and satellite or ground based photometries. As a by product, we have identified KIC 6950556 as a magnetic chemically peculiar star with an ACV type variability.
12. Refined Properties of the HD 130322 Planetary System
CERN Document Server
Hinkel, Natalie R; Henry, Gregory W; Feng, Y Katherina; Boyajian, Tabetha; Wright, Jason; Fischer, Debra A; Howard, Andrew W
2015-01-01
Exoplanetary systems closest to the Sun, with the brightest host stars, provide the most favorable opportunities for characterization studies of the host star and their planet(s). The Transit Ephemeris Refinement and Monitoring Survey uses both new radial velocity measurements and photometry in order to greatly improve planetary orbit uncertainties and the fundamental properties of the star, in this case HD 130322. The only companion, HD 130322b, orbits in a relatively circular orbit, e = 0.029 every ~10.7 days. Radial velocity measurements from multiple sources, including 12 unpublished from the Keck I telescope, over the course of ~14 years have reduced the uncertainty in the transit midpoint to ~2 hours. The transit probability for the b-companion is 4.7%, where M_p sin i = 1.15 M_J and a = 0.0925 AU. In this paper, we compile photometric data from the T11 0.8m Automated Photoelectric Telescope at Fairborn Observatory taken over ~14 years, including the constrained transit window, which results in a dispos...
13. Large HI structures linked to southern O-type stars
CERN Document Server
Martín, M C; Romero, G A
2008-01-01
In our search for interstellar bubbles around massive stars we analyze the environs of the O-type stars HD 38666, HD 124979, HD 163758, and HD 171589. The location of the stars, which are placed far from the galactic plane, favors the formation of large wind bubbles. We investigate the distribution of the neutral and ionized gas based on HI, CO, and radio continuum data, and that of the interstellar dust based on far infrared IRIS images. Here we report the discovery of neutral gas cavities and slowly expanding shells associated with the four massive stars. IR and optical counterparts were also detected for some of the stars. We discuss the probability that the features have originated in the action of the stellar winds on the surrounding gas.
14. Asteroseismology of the Transiting Exoplanet Host HD 17156 with Hubble Space Telescope Fine Guidance Sensor
DEFF Research Database (Denmark)
Gilliland, Ronald L.; McCullough, Peter R.; Nelan, Edmund P.;
2011-01-01
Observations conducted with the Fine Guidance Sensor on the Hubble Space Telescope (HST) providing high cadence and precision time-series photometry were obtained over 10 consecutive days in 2008 December on the host star of the transiting exoplanet HD 17156b. During this time, 1.0 × 1012 photons...
15. HD 181068: A Red Giant in a Triply Eclipsing Compact Hierarchical Triple System
DEFF Research Database (Denmark)
Derekas, A.; Kiss, Lazlo L.; Borkovits, T.;
2011-01-01
Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by gro...
16. The polarisation of HD 189733
CERN Document Server
Bott, Kimberly; Kedziora-Chudczer, Lucyna; Cotton, Daniel V; Lucas, P W; Marshall, Jonathan P; Hough, J H
2016-01-01
We present linear polarization observations of the exoplanet system HD 189733 made with the HIgh Precision Polarimetric Instrument (HIPPI) on the Anglo-Australian Telescope (AAT). The observations have higher precision than any previously reported for this object. They do not show the large amplitude polarization variations reported by Berdyugina et al. 2008 and Berdyugina et al. 2011. Our results are consistent with polarization data presented by Wiktorowicz et al. 2015. A formal least squares fit of a Rayleigh-Lambert model yields a polarization amplitude of 29.4 +/- 15.6 parts-per-million. We observe a background constant level of polarization of ~ 55-70 ppm, which is a little higher than expected for interstellar polarization at the distance of HD 189733.
17. Seismic analysis of HD 43587Aa, a solar-like oscillator in a multiple system
Science.gov (United States)
Boumier, P.; Benomar, O.; Baudin, F.; Verner, G.; Appourchaux, T.; Lebreton, Y.; Gaulme, P.; Chaplin, W.; García, R. A.; Hekker, S.; Regulo, C.; Salabert, D.; Stahn, T.; Elsworth, Y.; Gizon, L.; Hall, M.; Mathur, S.; Michel, E.; Morel, T.; Mosser, B.; Poretti, E.; Rainer, M.; Roxburgh, I.; do Nascimento, J.-D., Jr.; Samadi, R.; Auvergne, M.; Chaintreuil, S.; Baglin, A.; Catala, C.
2014-04-01
Context. The object HD 43587Aa is a G0V star observed during the 145-day LRa03 run of the COnvection, ROtation and planetary Transits space mission (CoRoT), for which complementary High Accuracy Radial velocity Planet Searcher (HARPS) spectra with S/N > 300 were also obtained. Its visual magnitude is 5.71, and its effective temperature is close to 5950 K. It has a known companion in a highly eccentric orbit and is also coupled with two more distant companions. Aims: We undertake a preliminary investigation of the internal structure of HD 43587Aa. Methods: We carried out a seismic analysis of the star, using maximum likelihood estimators and Markov chain Monte Carlo methods. Results: We established the first table of the eigenmode frequencies, widths, and heights for HD 43587Aa. The star appears to have a mass and a radius slightly larger than the Sun, and is slightly older (5.6 Gyr). Two scenarios are suggested for the geometry of the star: either its inclination angle is very low, or the rotation velocity of the star is very low. Conclusions: A more detailed study of the rotation and of the magnetic and chromospheric activity for this star is needed, and will be the subject of a further study. New high resolution spectrometric observations should be performed for at least several months in duration.
18. HD188112: Supernova Ia progenitor?
CERN Document Server
Latour, M; Heber, U; Schaffenroth, V
2015-01-01
HD188112 is an extremely low mass white dwarf in a close binary system. According to a previous study, the mass of HD188112 is $\\sim$0.24 Msun and a lower limit of 0.73 Msun could be put for the mass of its unseen companion, a compact degenarate object. We used HST STIS spectra to measure the rotational broadening of UV metallic lines in HD188112, in order to put tighter constraints on the mass of its companion. By assuming that the system in is synchronous rotation, we derive a companion mass between 1.05 and 1.25 Msun. We also measure abundances for magnesium, silicon, and iron, respectively log $N$(X)/$N$(H) = $-$6.40, $-$7.25, and $-$5.81. The radial velocities measured from the UV spectra are found to be in very good agreement with the prediction based on the orbital parameters derived in the previous study made a decade ago.
19. A High Eccentricity Component in the Double Planet System Around HD 163607 and a Planet Around HD 164509
CERN Document Server
Giguere, Matthew J; Howard, Andrew W; Johnson, John A; Henry, Gregory W; Wright, Jason T; Marcy, Geoffrey W; Isaacson, Howard T; Hou, Fengji; Spronck, Julien
2011-01-01
We report the detection of three new exoplanets from Keck Observatory. HD 163607 is a metal-rich G5IV star with two planets. The inner planet has an observed orbital period of 75.29 $\\pm$ 0.02 days, a semi-amplitude of 51.1 $\\pm$ 1.4 \\ms, an eccentricity of 0.73 $\\pm$ 0.02 and a derived minimum mass of \\msini = 0.77 $\\pm$ 0.02 \\mjup. This is the largest eccentricity of any known planet in a multi-planet system. The argument of periastron passage is 78.7 $\\pm$ 2.0$^{\\circ}$; consequently, the planet's closest approach to its parent star is very near the line of sight, leading to a relatively high transit probability of 8%. The outer planet has an orbital period of 3.60 $\\pm$ 0.02 years, an orbital eccentricity of 0.12 $\\pm$ 0.06 and a semi-amplitude of 40.4 $\\pm$ 1.3 \\ms. The minimum mass is \\msini = 2.29 $\\pm$ 0.16 \\mjup. HD 164509 is a metal-rich G5V star with a planet in an orbital period of 282.4 $\\pm$ 3.8 days and an eccentricity of 0.26 $\\pm$ 0.14. The semi-amplitude of 14.2 $\\pm$ 2.7 \\ms\\ implies a mini...
20. Research on propagation law of AE wave in coal seam
Institute of Scientific and Technical Information of China (English)
WEN Guang-cai; YANG Hui-ming; ZOU Yin-hui; DONG Guo-wei
2007-01-01
Based on mechanism of AE creation, put forward sphere cavity model, and deduced wave Equation of AE wave radiated by the AE source in detail, and analyzed the propagation attenuation law of AE stress wave in coal (rock) strata. Displacement function of AE wave indicates that displacement field can be divided into two parts. Firstly, displacement of particle is approaching to the source intensity function in zone near the AE source. Secondly, in zone far away from the AE source, displacement of particle is approaching to the derivative of source intensity function. AE wave changes gradually in the spreading process, and notable change of the wave form happens when wave propagates far away from the AE source.
1. The chemically peculiar double-lined spectroscopic binary HD 90264
Science.gov (United States)
Quiroga, C.; Torres, A. F.; Cidale, L. S.
2010-10-01
Context. HD 90264 is a chemically peculiar (CP) double-lined spectroscopic binary system of the type He-weak. Double-lined binaries are unique sources of data for stellar masses, physical properties, and evolutionary aspects of stars. Therefore, the determination of orbital elements is of great importance to study how the physical characteristics of CP stars are affected by a companion. Aims: We carried out a detailed spectral and polarimetric study of the spectroscopic binary system HD 90264 to characterize its orbit, determine the stellar masses, and investigate the spectral variability and possible polarization of the binary components. Methods: We employed medium-resolution échelle spectra and polarimetric data obtained at the 2.15-m telescope at CASLEO Observatory, Argentina. We measured radial velocities and line equivalent widths with IRAF packages. The radial velocity curves of both binary components were obtained combining radial velocity data derived from the single line of Hg II λ3984 Åand the double lines of Mg II λ4481 Å. Polarimetric data were studied by means of the statistical method of Clarke & Stewart and the Welch test. Results: We found that both components of the binary system are chemically peculiar stars, deficient in helium, where the primary is a He variable and the secondary is a Hg-Mn star. We derived for the first time the orbital parameters of the binary system. We found that the system has a quasi-circular orbit (e ~ 0.04) with an orbital period of 15.727 days. Taking into account the circular orbit solution, we derived a mass ratio of q = MHe-w/MHg-Mn = 1.22. We also found a rotational period of around 15-16 days, suggesting a spin-orbit synchronization. Possible signs of intrinsic polarization have also been detected. Conclusions: HD 90264 is the first known binary system comprised of a He variable star as the primary component and a Hg-Mn star as the secondary one. Based on observations taken at Complejo Astronómico El
2. Three Temperate Neptunes Orbiting Nearby Stars
CERN Document Server
Fulton, Benjamin J; Weiss, Lauren M; Sinukoff, Evan; Petigura, Erik A; Isaacson, Howard; Hirsch, Lea; Marcy, Geoffrey W; Henry, Gregory W; Grunblatt, Samuel K; Huber, Daniel; von Braun, Kaspar; Boyajian, Tabetha S; Kane, Stephen R; Wittrock, Justin; Horch, Elliott P; Ciardi, David R; Howell, Steve B; Wright, Jason T; Ford, Eric B
2016-01-01
We present the discovery of three modestly-irradiated, roughly Neptune-mass planets orbiting three nearby Solar-type stars. HD 42618 b has a minimum mass of $15.4 \\pm 2.4$ M$_{\\oplus}$, a semi-major axis of 0.55 AU, an equilibrium temperature of 337 K, and is the first planet discovered to orbit the solar analogue host star, HD 42618. We also discover new planets orbiting the known exoplanet host stars HD 164922 and HD 143761 ($\\rho$ CrB). The new planet orbiting HD 164922 has a minimum mass of $12.9 \\pm 1.6$ M$_{\\oplus}$ and orbits interior to the previously known Jovian mass planet orbiting at 2.1 AU. HD 164922 c has a semi-major axis of 0.34 AU and an equilibrium temperature of 418 K. HD 143761 c orbits with a semi-major axis of 0.44 AU, has a minimum mass of $25 \\pm 2$ M$_{\\oplus}$, and is the warmest of the three new planets with an equilibrium temperature of 445 K. It orbits exterior to the previously known warm Jupiter in the system. A transit search using space-based CoRoT data and ground-based photom...
3. The dust, planetesimals and planets of HD 38529
CERN Document Server
Moro-Martin, Amaya; Carpenter, John M; Hillenbrand, Lynne A; Wolf, Sebastian; Meyer, Michael R; Hollenbach, David J; Najita, Joan; Henning, Thomas
2007-01-01
HD 38529 is a post-main sequence G8III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having Msin(i) of 0.8 MJup and 12.2 MJup, semimajor axes of 0.13 AU and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 micron of 4.7, a small excess at 33 micron (S/N=2.6) and no excess <30 micron. We discuss the distribution of the potential dust-producing planetesimals from the study of the dynamical perturbations of the two known planets, considering in particular the effect of secular resonances. We identify three dynamically stable niches at 0.4-0.8 AU, 20-50 AU and beyond 60 AU. We model the spectral energy distribution of HD 38529 to find out which of these niches show signs of harboring dust-producing plantesimals. The secular analysis, together with the SED modeling resuls, suggest that the planetesimals responsible for most of the du...
4. High Dispersion Absorption-line Spectroscopy of AE Aqr
CERN Document Server
Echevarria, J; Costero, R; Zharikov, S; Michel, R
2008-01-01
High-dispersion time-resolved spectroscopy of the unique magnetic cataclysmic variable AE Aqr is presented. A radial velocity analysis of the absorption lines yields K_2 = 168.7+/- 1 km/s. Substantial deviations of the radial velocity curve from a sinusoid are interpreted in terms of intensity variations over the secondary star's surface. A complex rotational velocity curve as a function of orbital phase is detected which has a modulation frequency of twice the orbital frequency, leading to an estimate of the binary inclination angle that is close to 70^o. The minimum and maximum rotational velocities are used to indirectly derive a mass ratio of q= 0.6 and a radial velocity semi-amplitude of the white dwarf of K_1 = 101+/-3 km/s. We present an atmospheric temperature indicator, based on the absorption line ratio of Fe I and Cr I lines, whose variation indicates that the secondary star varies from K0 to K4 as a function of orbital phase. The ephemeris of the system has been revised, using more than one thousa...
5. Photometric Variability of Four Coronally Active Stars
J. C. Pandey; K. P. Singh; R. Sagar; S. A. Drake
2002-03-01
We present photometric observations of four stars that are optical counterparts of soft X-ray/EUV sources, namely 1ES 0829+15.9, 1ES0920-13.6, 2RE J110159+223509 and 1ES 1737+61.2. We have discovered periodic variability in two of the stars, viz., MCC 527 (1ES 0829+15.9; Period = 0.828 ± 0.0047) and HD 81032 (1ES 0920-13.6; Period = ∼ 57.02 ± 0.560 days). HD 95559 (2RE J110159+223509) is found to show a period of 3. HD 160934 (1ES1737+61.2) also shows photometric variability but needs to be monitored further for finding its period. These stars most likely belong to the class of chromospherically active stars.
6. Star Formation Regions in LDN 1667
Science.gov (United States)
Gyulbudaghian, A. L.
2015-09-01
A group of three star formation regions in the dark cloud LDN 1667 is examined. All three of these regions contain Trapezium type systems. 12C(1-0) observations are made of the part of the molecular cloud LDN 1667 associated with one of the star formation regions. Three molecular clouds were detected, one of which (the main cloud) has a red and a blue outflow. Three stars from the star formation regions are found to have annular nebulae and one star has a conical nebula. The dark cloud LDN 1667 is associated with a radial system of dark globules which is formed by the star HD 57061.
7. The Dushak–Erekdag Survey of roAp Stars
Tatyana Dorokhova; Nikolay Dorokhov
2005-06-01
The search of roAp stars at Mt. Dushak–Erekdag Observatory was started in 1992 using the 0.8m Odessa telescope equipped with a two-star high-speed photometer. We have observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD+8087 is suspected to have rapid oscillations. Negative results of our observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.
8. A Massive Substellar Companion to the Massive Giant HD 119445
CERN Document Server
Omiya, Masashi; Han, Inwoo; Lee, Byeong-Cheol; Sato, Bun'ei; Kambe, Eiji; Kim, Kang-Min; Yoon, Tae Seog; Yoshida, Michitoshi; Masuda, Seiji; Toyota, Eri; Urakawa, Seitaro; Takada-Hidai, Masahide
2009-01-01
We detected a brown dwarf-mass companion around the intermediate-mass giant star HD 119445 (G6III) using the Doppler technique. This discovery is the first result from a Korean-Japanese planet search program based on precise radial velocity measurements. The radial velocity of this star exhibits a periodic Keplerian variation with a period, semi-amplitude and eccentricity of 410.2 days, 413.5 m/s and 0.082, respectively. Adopting a stellar mass of 3.9 M_solar, we were able to confirm the presence of a massive substellar companion with a semimajor axis of 1.71 AU and a minimum mass of 37.6 M_Jup, which falls in the middle of the brown dwarf-mass region. This substellar companion is the most massive ever discovered within 3 AU of a central intermediate-mass star. The host star also ranks among the most massive stars with substellar companions ever detected by the Doppler technique. This result supports the current view of substellar systems that more massive substellar companions tend to exist around more massi...
9. HD depletion in starless cores
OpenAIRE
Sipilä, O.; Caselli, P.; Harju, J.
2013-01-01
Aims: We aim to investigate the abundances of light deuterium-bearing species such as HD, H2D+ and D2H+ in a gas-grain chemical model including an extensive description of deuterium and spin state chemistry, in physical conditions appropriate to the very centers of starless cores. Methods: We combine a gas-grain chemical model with radiative transfer calculations to simulate density and temperature structure in starless cores. The chemical model includes deuterated forms of species with up to...
10. HD 51844: An Am delta Scuti in a binary showing periastron brightening
CERN Document Server
Hareter, M; Weiss, W W; Hernández, A García; Borkovits, T; Lampens, P; Rainer, M; De Cat, P; Marcos-Arenal, P; Vos, J; Poretti, E; Baglin, A; Michel, E; Baudin, F; Catala, C
2014-01-01
Pulsating stars in binary systems are ideal laboratories to test stellar evolution and pulsation theory, since a direct, model-independent determination of component masses is possible. The high-precision CoRoT photometry allows a detailed view of the frequency content of pulsating stars, enabling detection of patterns in their distribution. The object HD 51844 is such a case showing periastron brightening instead of eclipses. We present a comprehensive study of the HD 51844 system, where we derive physical parameters of both components, the pulsation content and frequency patterns. Additionally, we obtain the orbital elements, including masses, and the chemical composition of the stars. Time series analysis using standard tools was mployed to extract the pulsation frequencies. Photospheric abundances of 21 chemical elements were derived by means of spectrum synthesis. We derived orbital elements both by fitting the observed radial velocities and the light curves, and we did asteroseismic modelling as well. W...
11. Study of HD 169392A observed by CoRoT and HARPS
CERN Document Server
Mathur, S; Catala, C; Benomar, O; Davies, G R; Garcia, R A; Salabert, D; Ballot, J; Mosser, B; Regulo, C; Chaplin, W J; Elsworth, Y; Handberg, R; Hekker, S; Mantegazza, L; Michel, E; Poretti, E; Rainer, M; Roxburgh, I W; Samadi, R; Steslicki, M; Uytterhoeven, K; Verner, G A; Auvergne, M; Baglin, A; Forteza, S Barcelo; Baudin, F; Cortes, T Roca
2012-01-01
The numerous results obtained with asteroseismology thanks to space missions such as CoRoT and Kepler are providing a new insight on stellar evolution. After five years of observations, CoRoT is going on providing high-quality data. We present here the analysis of the double star HD169392 complemented by ground-based spectroscopic observations. This work aims at characterizing the fundamental parameters of the two stars, their chemical composition, the acoustic-mode global parameters including their individual frequencies, and their dynamics. We have analysed HARPS observations of the two stars to retrieve their chemical compositions. Several methods have been used and compared to measure the global properties of acoustic modes and their individual frequencies from the photometric data of CoRoT. The new spectroscopic observations and archival astrometric values suggest that HD169392 is a wide binary system weakly bounded. We have obtained the spectroscopic parameters for both components, suggesting the origin...
12. Spectropolarimetric observations of the transiting planetary system of the K dwarf HD 189733
CERN Document Server
Moutou, C; Savalle, R; Hussain, G; Alecian, E; Bouchy, F; Catala, C; Cameron, A Collier; Udry, S; Vidal-Madjar, A
2007-01-01
With a Jupiter-mass planet orbiting at a distance of only 0.031 AU, the active K2 dwarf HD 189733 is a potential candidate in which to study the magnetospheric interactions of a cool star with its recently-discovered close-orbiting giant planet. We decided to explore the strength and topology of the large-scale magnetosphere of HD 189733, as a future benchmark for quantitative studies for models of the star/planet magnetic interactions. To this end, we used ESPaDOnS, the new generation spectropolarimeter at the Canada-France-Hawaii 3.6m telescope, to look for Zeeman circular polarisation signatures in the line profiles of HD 189733 in 2006 June and August. Zeeman signatures in the line profiles of HD 189733 are clearly detected in all spectra, demonstrating that a field is indeed present at the surface of the star. The Zeeman signatures are not modulated with the planet's orbital period but apparently vary with the stellar rotation cycle. The reconstructed large-scale magnetic field, whose strength reaches a ...
13. HD 5388 b is a 69 M_Jup companion instead of a planet
CERN Document Server
Sahlmann, Johannes; Queloz, Didier; Segransan, Damien
2011-01-01
We examined six exoplanet host stars with non-standard Hipparcos astrometric solution, which may be indicative of unrecognised orbital motion. Using Hipparcos intermediate astrometric data, we detected the astrometric orbit of HD 5388 at a significance level of 99.4 % (2.7 sigma). HD 5388 is a metal-deficient star and hosts a planet candidate with a minimum mass of 1.96 M_J discovered in 2010. We determined its orbit inclination to be i = 178.3 +0.4/-0.7 deg and the corresponding mass of its companion HD 5388 b to be M_2 = 69 +/- 20 M_J. The orbit is seen almost face-on and the companion mass lies at the upper end of the brown-dwarf mass range. A mass lower than 13 M_J was excluded at the 3-sigma level. The astrometric motions of the five other stars had been investigated by other authors revealing two planetary companions, one stellar companion, and two statistically insignificant orbits. We conclude that HD 5388 b is not a planet but most likely a brown-dwarf companion. In addition, we find that the inclina...
14. Discovery of a magnetic field in the B pulsating system HD 1976
OpenAIRE
Neiner, C.; Tkachenko, A.; collaboration, the MiMeS
2014-01-01
The presence of a magnetic field can have a strong impact on the evolution of a binary star. However, only a dozen of magnetic OB binaries are known as of today and available to study this effect, including very few magnetic pulsating spectroscopic OB binaries. We aim at checking for the presence of a magnetic field in the B5IV hierarchical triple system HD 1976 with spectropolarimetric data obtained with Narval at the Bernard Lyot Telescope (TBL). We use orbital parameters of HD 1976 availab...
15. HD 46375: seismic and spectropolarimetric analysis of a young Sun hosting a Saturn-like planet
OpenAIRE
Gaulme, P.; Deheuvels, S.; Weiss, W. W.; Mosser, B.; Moutou, C.; Bruntt, H; Donati, J.-F.; Vannier, M.; Guillot, T.; Appourchaux, T.; Michel, E.; Auvergne, M.; Samadi, R.; Baudin, F; Catala, C.
2010-01-01
HD 46375 is known to host a Saturn-like exoplanet orbiting at 0.04 AU from its host star. Stellar light reflected by the planet was tentatively identified in the 34-day CoRoT run acquired in October-November 2008. We constrain the properties of the magnetic field of HD 46375 based on spectropolarimetric observations with the NARVAL spectrograph at the Pic du Midi observatory. In addition, we use a high-resolution NARVAL flux spectrum to contrain the atmospheric parameters. With these constrai...
16. First Observation of Planet-Induced X-ray Emission: The System HD 179949
OpenAIRE
Saar, S. H.; Cuntz, M.; Kashyap, V. L.; Hall, J. C.
2007-01-01
We present the first observation of planet-induced stellar X-ray activity, identified for the HD 179949 system, using Chandra / ACIS-S. The HD 179949 system consists of a close-in giant planet orbiting an F9V star. Previous ground-based observations already showed enhancements in Ca II K in phase with the planetary orbit. We find an ~30% increase in the X-ray flux over quiescent levels coincident with the phase of the Ca II enhancements. There is also a trend for the emission to be hotter at ...
17. AES Water Architecture Study Interim Results
Science.gov (United States)
Sarguisingh, Miriam J.
2012-01-01
The mission of the Advanced Exploration System (AES) Water Recovery Project (WRP) is to develop advanced water recovery systems in order to enable NASA human exploration missions beyond low earth orbit (LEO). The primary objective of the AES WRP is to develop water recovery technologies critical to near term missions beyond LEO. The secondary objective is to continue to advance mid-readiness level technologies to support future NASA missions. An effort is being undertaken to establish the architecture for the AES Water Recovery System (WRS) that meets both near and long term objectives. The resultant architecture will be used to guide future technical planning, establish a baseline development roadmap for technology infusion, and establish baseline assumptions for integrated ground and on-orbit environmental control and life support systems (ECLSS) definition. This study is being performed in three phases. Phase I of this study established the scope of the study through definition of the mission requirements and constraints, as well as indentifying all possible WRS configurations that meet the mission requirements. Phase II of this study focused on the near term space exploration objectives by establishing an ISS-derived reference schematic for long-duration (>180 day) in-space habitation. Phase III will focus on the long term space exploration objectives, trading the viable WRS configurations identified in Phase I to identify the ideal exploration WRS. The results of Phases I and II are discussed in this paper.
18. Acceleration of AES encryption on CUDA GPU
Directory of Open Access Journals (Sweden)
Takakazu Kurokawa
2012-01-01
Full Text Available
GPU exhibits the capability for applications with a high level of parallelism despite its low cost. The support of integer and logical instructions by the latest generation of GPUs enables us to implement cipher algorithms more easily. However, decisions such as parallel processing granularity and memory allocation impose a heavy burden on programmers. Therefore, this paper presents results of several experiments that were conducted to elucidate the relation between memory allocation styles of variables of AES and granularity as the parallelism exploited from AES encoding processes using CUDA with an NVIDIA GeForce GTX285 (Nvidia Corp.. Results of these experiments showed that the 16 bytes/thread granularity had the highest performance. It achieved approximately 35 Gbps throughput. It also exhibited differences of memory allocation and granularity effects around 2%–30% for performance in standard implementation. It shows that the decision of granularity and memory allocation is the most important factor for effective processing in AES encryption on GPU. Moreover, implementation with overlapping between processing and data transfer yielded 22.5 Gbps throughput including the data transfer time.
19. A 12-Year Activity Cycle for HD 219134
CERN Document Server
Johnson, Marshall C; Cochran, William D; Meschiari, Stefano; Robertson, Paul; MacQueen, Phillip J; Brugamyer, Erik J; Caldwell, Caroline; Hatzes, Artie P; Ramírez, Ivan; Wittenmyer, Robert A
2016-01-01
The nearby (6.5 pc) star HD 219134 was recently shown by Motalebi et al. (2015) and Vogt et al. (2015) to host several planets, the innermost of which is transiting. We present twenty-seven years of radial velocity observations of this star from the McDonald Observatory Planet Search program, and nineteen years of stellar activity data. We detect a long-period activity cycle measured in the Ca II $S_{HK}$ index, with a period of $4230 \\pm 100$ days (11.7 years), very similar to the 11-year Solar activity cycle. Although the period of the Saturn-mass planet HD 219134 h is close to half that of the activity cycle, we argue that it is not an artifact due to stellar activity. We also find a significant periodicity in the $S_{HK}$ data due to stellar rotation with a period of 22.8 days. This is identical to the period of planet f identified by Vogt et al. (2015), suggesting that this radial velocity signal might be caused by rotational modulation of stellar activity rather than a planet. Analysis of our radial vel...
20. Magnetic fields of HgMn stars
DEFF Research Database (Denmark)
Hubrig, S.; Gonzalez, J. F.; Ilyin, I.;
2012-01-01
Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... by applying the moment technique on spectral lines of inhomogeneously distributed elements separately. Furthermore, we present new determinations of the mean longitudinal magnetic field for the HgMn star HD 65949 and the hotter analog of HgMn stars, the PGa star HD 19400, using FORS 2 installed at the VLT. We...... also give new measurements of the eclipsing system ARAur with a primary star of HgMn peculiarity, which were obtained with the SOFIN spectropolarimeter installed at the Nordic Optical Telescope. Methods. We downloaded from the European Southern Observatory (ESO) archive the publically available HARPS... | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8952294588088989, "perplexity": 6604.381517214804}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-22/segments/1495463607806.46/warc/CC-MAIN-20170524074252-20170524094252-00013.warc.gz"} |
http://community.wolfram.com/groups/-/m/t/324335?p_p_auth=L9m0NmEv | # Moments of a generic random variable (symbolic)
GROUPS:
Daniela Scida 1 Vote Hi, I'm having trouble to find how write moments of random variables in symbolic terms. For instance, say I define z = x + y then I want to compute the variance of z in terms of moments of x and y. I would like Mathematica to return this:Variance(z) = variance(x) + variance(y) + 2*covariance(x,y)(All in symbolic terms) My actual problem is a bit more complicated. I have that the data generating process of a scalar random variable X is an AR(p): $X_{t} = \sum_{j=1}^{p} A_{j} X_{t-j} + u_{t}$where $A_{j}$'s are scalars, for some white noise $u_{t}$. I don't want to specify a distribution for $u_{t}$, and there is NO data nor estimation involved. This is a population exercise. I want to compute the variance of $X_{t}$ as a function of $p$, the $A_{j}$'s, and probably the variance of $u_{t}$. The process is stationary.MY QUESTION: can mathematica give me the expression of Variance( $X_{t}$ ) in symbolic terms? Thanks!!!! All help/comments welcome!PS Just in case I'm familiar with the well known formula for it, but I don't want to write that directly. I want mathematic to tell me the expression. The reason is that I also have more complicated processes to look into where deriving the variance is a mess, so I would like mathematica to do it for me. For instance, I have VAR(p) processes for X and Y.
2 years ago
6 Replies
Jim Baldwin 2 Votes You might consider the mathStatica book/package at mathstatica.comAlso, you have a minor typo: "- 2 * covariance(x,y)" should be "+ 2 * covariance(x,y)".
2 years ago
@Jim Thanks! I actually looked into mathStatica before, but it seems you need to buy it? (And yes there was a minor, I was tired when I wrote it...Thanks!)
2 years ago
Yes, one does need to purchase mathStatica but it is well worth it.
2 years ago
Awesome! Thanks! I'll keep that in mind.
Gosia Konwerska 4 Votes Assuming weak stationarity of AR process: In[1]:= Variance[ARProcess[{a1, a2}, var][t]] Out[1]= -(((-1 + a2) var)/((1 + a2) (1 - a1^2 - 2 a2 + a2^2))) gives the answer for p=2 and for var denoting the variance of white noise driving the process. In Mathematica ARProcess is assumed to be driven by a Gaussian white noise, but this formula is more general - assuming zero first moment and finite second moment of the noise. We also assume that the noise variable is independent of past observations.Clearly it becomes more complicated in higher dimensions: In[2]:= Variance[ARProcess[{Array[a, {2, 2}]}, Array[v, {2, 2}]][t]] Out[2]= {-((v[1, 1] - a[1, 2] a[2, 1] v[1, 1] - a[1, 1] a[2, 2] v[1, 1] - a[2, 2]^2 v[1, 1] - a[1, 2] a[2, 1] a[2, 2]^2 v[1, 1] + a[1, 1] a[2, 2]^3 v[1, 1] + a[1, 1] a[1, 2] v[1, 2] + a[1, 2]^2 a[2, 1] a[2, 2] v[1, 2] - a[1, 1] a[1, 2] a[2, 2]^2 v[1, 2] + a[1, 1] a[1, 2] v[2, 1] + a[1, 2]^2 a[2, 1] a[2, 2] v[2, 1] - a[1, 1] a[1, 2] a[2, 2]^2 v[2, 1] + a[1, 2]^2 v[2, 2] - a[1, 2]^3 a[2, 1] v[2, 2] + a[1, 1] a[1, 2]^2 a[2, 2] v[2, 2])/(-1 + a[1, 1]^2 + a[1, 2] a[2, 1] + a[1, 1]^2 a[1, 2] a[2, 1] + a[1, 2]^2 a[2, 1]^2 - a[1, 2]^3 a[2, 1]^3 + a[1, 1] a[2, 2] - a[1, 1]^3 a[2, 2] + 3 a[1, 1] a[1, 2]^2 a[2, 1]^2 a[2, 2] + a[2, 2]^2 - a[1, 1]^2 a[2, 2]^2 + a[1, 2] a[2, 1] a[2, 2]^2 - 3 a[1, 1]^2 a[1, 2] a[2, 1] a[2, 2]^2 - a[1, 1] a[2, 2]^3 + a[1, 1]^3 a[2, 2]^3)), -((-a[2, 1]^2 v[1, 1] + a[1, 2] a[2, 1]^3 v[1, 1] - a[1, 1] a[2, 1]^2 a[2, 2] v[1, 1] - a[1, 1] a[1, 2] a[2, 1]^2 v[1, 2] - a[2, 1] a[2, 2] v[1, 2] + a[1, 1]^2 a[2, 1] a[2, 2] v[1, 2] - a[1, 1] a[1, 2] a[2, 1]^2 v[2, 1] - a[2, 1] a[2, 2] v[2, 1] + a[1, 1]^2 a[2, 1] a[2, 2] v[2, 1] - v[2, 2] + a[1, 1]^2 v[2, 2] + a[1, 2] a[2, 1] v[2, 2] + a[1, 1]^2 a[1, 2] a[2, 1] v[2, 2] + a[1, 1] a[2, 2] v[2, 2] - a[1, 1]^3 a[2, 2] v[2, 2])/(1 - a[1, 1]^2 - a[1, 2] a[2, 1] - a[1, 1]^2 a[1, 2] a[2, 1] - a[1, 2]^2 a[2, 1]^2 + a[1, 2]^3 a[2, 1]^3 - a[1, 1] a[2, 2] + a[1, 1]^3 a[2, 2] - 3 a[1, 1] a[1, 2]^2 a[2, 1]^2 a[2, 2] - a[2, 2]^2 + a[1, 1]^2 a[2, 2]^2 - a[1, 2] a[2, 1] a[2, 2]^2 + 3 a[1, 1]^2 a[1, 2] a[2, 1] a[2, 2]^2 + a[1, 1] a[2, 2]^3 - a[1, 1]^3 a[2, 2]^3))}
Gosia Konwerska 2 Votes In[1]:= ARProcess[{Array[a, {2, 2}]}, Array[v, {2, 2}]] Out[1]= ARProcess[{{{a[1, 1], a[1, 2]}, {a[2, 1], a[2, 2]}}}, {{v[1, 1], v[1, 2]}, {v[2, 1], v[2, 2]}}] denotes AR process of order p=1, dimension 2. The coefficients of a vector process are defined to be square matrices n by n, where n is the dimension of the process. So to define 2-dimensional AR process of order say p=4 with symbolic coefficients using Array one does: In[2]:= ARProcess[{Array[a, {4, 2, 2}]}, Array[v, {2, 2}]] Out[2]= ARProcess[{{{{a[1, 1, 1], a[1, 1, 2]}, {a[1, 2, 1], a[1, 2, 2]}}, {{a[2, 1, 1], a[2, 1, 2]}, {a[2, 2, 1], a[2, 2, 2]}}, {{a[3, 1, 1], a[3, 1, 2]}, {a[3, 2, 1], a[3, 2, 2]}}, {{a[4, 1, 1], a[4, 1, 2]}, {a[4, 2, 1], a[4, 2, 2]}}}}, {{v[1, 1], v[1, 2]}, {v[2, 1], v[2, 2]}}] One could also use different names for each coefficient matrix: In[3]:= ARProcess[{Array[a, {3, 3}], Array[b, {3, 3}]}, Array[v, {3, 3}]] Out[3]= ARProcess[{{{a[1, 1], a[1, 2], a[1, 3]}, {a[2, 1], a[2, 2], a[2, 3]}, {a[3, 1], a[3, 2], a[3, 3]}}, {{b[1, 1], b[1, 2], b[1, 3]}, {b[2, 1], b[2, 2], b[2, 3]}, {b[3, 1], b[3, 2], b[3, 3]}}}, {{v[1, 1], v[1, 2], v[1, 3]}, {v[2, 1], v[2, 2], v[2, 3]}, {v[3, 1], v[3, 2], v[3, 3]}}] which defines AR process of order 2 and dimension 3, with coefficient matrices a and b, and noise covariance matrix v.This may also be helpful: ARProcess reference page | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.25414028763771057, "perplexity": 11755.168571960925}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-40/segments/1474738660746.32/warc/CC-MAIN-20160924173740-00001-ip-10-143-35-109.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/simple-harmonic-motion.744896/ | # Simple harmonic motion
1. Mar 23, 2014
### puhdanks
The problem is a ball is dropped onto a spring and the spring compresses .95m. The ball then sticks to the spring and oscillates with a period of 1.1 seconds and has a mass of 6kg.
I thought that the equation mg(h+x)=1/2(k)(x^2) would be what i would use.
I got h=.47m I also figured out that k= 61.96N/M i tried using this equation for another problem and it did not work. I am not sure if this is the right answer. Also How would i find how much the spring would be compressed when the spring stopped oscillating and was at rest.
2. Mar 23, 2014
### guitarphysics
What are you actually asked to find? You forgot to mention that. What do you mean by h? Always try to define whatever extra variables you use on here so people can understand what you mean.
3. Mar 23, 2014
### puhdanks
opps sry lol i have to find from what height the ball was dropped from
4. Mar 23, 2014
### guitarphysics
Ok, cool, that's better. Thanks. It seemed like that was the question, just wanted to make sure. How did you arrive at that result for k? You should have used the equation that tells you the period of a mass on a spring as a function of mass and spring constant. You can find it here: http://en.wikipedia.org/wiki/Simple_harmonic_motion#Mass_on_a_spring
I think that's the part you got wrong. The other part seems to be fine. Hope this helped, good luck.
5. Mar 23, 2014
### puhdanks
I used k=F/x but when i use the equation T=2Pi(sqrt(M/K) i get a different answer
6. Mar 23, 2014
### guitarphysics
How would you know F?
7. Mar 23, 2014
### guitarphysics
Oh, I see what you did. You equaled the weight of the mass with the force that was being applied by the spring once the mass hit the bottom? That's not right, because when it's at the bottom, the mass *does* have an upwards acceleration (so the force from the spring is greater than its weight, not equal to it). The mass happens to have zero velocity, but its acceleration is certainly not zero. The other equation does hold, though.
8. Mar 23, 2014
### puhdanks
I ended up getting .587m does that seem right?
Draft saved Draft deleted
Similar Discussions: Simple harmonic motion | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9240759611129761, "perplexity": 799.5831218882139}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-09/segments/1518891807825.38/warc/CC-MAIN-20180217204928-20180217224928-00590.warc.gz"} |
http://math.stackexchange.com/questions/671795/induction-proof-of-function-from-mathbb-r-to-mathbb-r | Induction proof of function from $\mathbb R$ to $\mathbb R$
Let f be a function from $\mathbb R$ to $\mathbb R$ satisfying $f(\frac{x_1+x_2}{2})=\frac{f(x_1)+f(x_2)}{2}$
Prove that for any positive integer $n$ we have $f(\frac{x_1+x_2\dots+x_n}{n})=\frac{f(x_1)+f(x_2)+\dots+f(x_n)}{n}$
Regards.
I managed to prove it for all powers of 2. Mabye it is a case of cauchy induction? Thanks in advance.
Regards
-
I can't seem to find the induction step. I tried direct normal induction but I can't do it. – Gamamal Feb 11 '14 at 3:27
Put $a=\frac{x_1+...+x_n}{n}$ and $m=2^k>n$.
Then \begin{align}f(a)&=f\left(\frac{\frac{m}{n}(x_1+...+x_n)}{m}\right)\\&=f\left(\frac{x_1+...+x_n+(m-n)a}{m}\right)\\&=f\left(\frac{x_1+...+x_n+a+a+...+a}{m}\right)\\&=\frac{f(x_1)+...+f(x_n)+f(a)+f(a)+...+f(a)}{m}\\&=\frac{f(x_1)+...+f(x_n)+(m-n)f(a)}{m}\\&=\frac{f(x_1)+...+f(x_n)}{m}+\frac{(m-n)}{m}f(a)\end{align}
The third equality is using that you already know that it is true for powers of $2$, and $m=2^k$.
Solve for $f(a)$ and you get it.
-
I think 6our answer has a tiny mistake.you need to change m for n+1. It is a regular cauchy induction. – Gamamal Feb 11 '14 at 15:09
@user4140 It is indeed just Cauchy's induction, that is why $m$ cannot be $n+1$. We need $m$ to be a power of $2$ larger than $n$ for which you have already proved the formula by induction. – user127249 Feb 11 '14 at 16:11
I think it needs to be n+1. For the argument to work. Mainly because: How do you know f((m-n)a)=(m-n)(f(a)) And there aren't necessary m terms in the second to last sum. – Gamamal Feb 11 '14 at 22:34
@user4140 We are never using that. We don't even know if that is true. What we are using is that $f(\frac{x_1+...+x_n+(m-n)a}{m})=f(\frac{x_1+...+x_n+a+a+...+a}{m})=\frac{f(x_1)+...+f(x_n)+f(a)+f(a)+...+f(a)}{m}$, which is the know property for the average of $m=2^k$ numbers. I though you knew how Cauchy's induction goes. – user127249 Feb 11 '14 at 22:58
I added those intermediate steps above in the proof so you understand what is going on. – user127249 Feb 11 '14 at 23:01 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 1, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.958149254322052, "perplexity": 422.82207036198525}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375097204.8/warc/CC-MAIN-20150627031817-00148-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://galileoandeinstein.phys.virginia.edu/Elec_Mag/2022_Lectures/EM_02_Surfaces.html | # 2. Boundary Conditions at Surfaces
## Introduction
Following Jackson (we’ve got to section 1.5) we’ll look at interfaces between media. It’s a slight puzzle why Jackson does this now, he assumes you’ve seen the integral form of Maxwell’s equations in an undergraduate course, and we’ll go along. First we’ll look at field discontinuities on going say from air into glass, then we’ll review the closely related problem of field discontinuity from a surface charge layer, finally we’ll examine a dipole layer, which we’ll need shortly.
## Field Discontinuities at an Interface between Media
Imagine a locally flat interface between two uniform materials having different $\epsilon ,\mu .$ (We don’t take the more general tensor form.)
In this section, we’ll assume there is no charge or current on the interface.
We’re interested in how the electric and magnetic field vectors change on crossing from one medium to the other.
First we’ll examine the change in the normal to the surface components of the fields.
We find this by using the first two Maxwell equations (in integral form):
$\underset{S}{\oint }\stackrel{\to }{D}\cdot \stackrel{\to }{n}da=\underset{V}{\int }\rho {d}^{3}x=0,\text{ }\underset{S}{\oint }\stackrel{\to }{B}\cdot \stackrel{\to }{n}da=0.$
The trick is to integrate the vector fields over the complete surface of a vanishingly small pillbox, very thin, having its circular flat surfaces one in each medium.
The area of the cylindrical sides goes to zero in the limit we’re interested in, and the pillbox is so small we can take the field constant over the range of the integral, so, (for no charge at the boundary surface between the media)
${\stackrel{\to }{D}}_{1}\cdot \stackrel{\to }{n}={\stackrel{\to }{D}}_{2}\cdot \stackrel{\to }{n},\text{ }{\stackrel{\to }{B}}_{1}\cdot \stackrel{\to }{n}={\stackrel{\to }{B}}_{2}\cdot \stackrel{\to }{n}.$
This is often written as ${D}_{1\perp }={D}_{2\perp },\text{ }{B}_{1\perp }={B}_{2\perp }.$
Note that since ${\stackrel{\to }{D}}_{1}={\epsilon }_{1}{\stackrel{\to }{E}}_{1},\text{ }{\stackrel{\to }{D}}_{2}={\epsilon }_{2}{\stackrel{\to }{E}}_{2},$ this is not the same as ${\stackrel{\to }{E}}_{1}\cdot \stackrel{\to }{n}={\stackrel{\to }{E}}_{2}\cdot \stackrel{\to }{n}$!
The tangential components can be found using the other two Maxwell equations,
$\underset{C}{\oint }\stackrel{\to }{H}\cdot d\stackrel{\to }{l}=\underset{{S}^{\prime }}{\int }\left[\stackrel{\to }{J}+\frac{\partial \stackrel{\to }{D}}{\partial t}\right]\cdot {\stackrel{\to }{n}}^{\prime }da,\text{ }\underset{C}{\oint }\stackrel{\to }{E}\cdot d\stackrel{\to }{l}=-\underset{{S}^{\prime }}{\int }\frac{\partial \stackrel{\to }{B}}{\partial t}\cdot {\stackrel{\to }{n}}^{\prime }da.$
Recall the left-hand sides are integrals around loops, the right-hand sides integrals over surfaces spanning the loops.
We choose as loops of integration tiny rectangles with long sides parallel to the surface and very close but on opposite sides, and much shorter sides perpendicular to the surface. The contribution to the loop integral from these shorter sides vanishes in the thin limit, and the result is ${E}_{1\text{\hspace{0.17em}}||}={E}_{2\text{ }||},\text{ }{H}_{1\text{\hspace{0.17em}}||}={H}_{2\text{ }||}.$
It is straightforward to generalize to the case where the surface has nonzero charge density and/or current density:
$\stackrel{\to }{n}×\left({\stackrel{\to }{H}}_{2}-{\stackrel{\to }{H}}_{1}\right)=\stackrel{\to }{K},$
the vector $\stackrel{\to }{K}$ being the surface current density.
## Electric Field Discontinuity across a Charged Surface
This seems a good place to add a very similar scenario: a flat plane of charge in vacuum, charge density $\sigma$ coul/m2. Assuming no other charges are present, the electric fields on the two sides of the plane will be uniform, perpendicular to the plane and in opposite directions on the two sides, both pointing outwards if the plane is positively charged. The magnitude of the fields is easily found by using Gauss’ law for a pillbox shape, two round flat sides of area $A$ parallel to the sheet of charge and on opposite sides. The cylindrical side is taken to go to zero in the limit. The enclosed charge is $\sigma A,$ the flat sides contribute $2EA$ to the Gaussian integral, so
$E=±\sigma /2{\epsilon }_{0}.$
There is a discontinuity in the normal component (the only one present in this example) of the electric field.
Let’s think a little further concerning this discontinuity. Imagine we’re looking in the neighborhood of a point $P$ which is a tiny distance $\delta$ from the plane. If we now move $P$ through the plane, it experiences this discontinuity in field.
Now, mentally split the field in this small region into two contributions, that from charge within a small circle around where $P$ passed through the plane, the other contribution from the (further away) rest of the plane, that is, from a plane with a small hole in it, and we’re looking at the electric field on going through the middle of the hole, along a line perpendicular to the plane. The electric field from this rest of the plane has to be continuous along this line$—$so the discontinuity is generated entirely by the very local charge distribution.
It follows that for any reasonably smooth surface, not necessarily plane, having in general varying charge density, there will be a discontinuity in the normal component of the electric field of magnitude depending on the local charge $\sigma \left(\stackrel{\to }{r}\right)/{\epsilon }_{0}$ on passing through it.
## Electric Potential Change across a Dipole Surface
Dipole surfaces are certainly less common, although they do exist in biological systems. But they also come up in some important mathematics, as we’ll see in a while, so this is worth thinking through.
### The Dipole
Before analyzing the dipole surface, let's remind ourselves about a single dipole. The dipole is defined as the limit of two equal and opposite charges $±q$, separated by a small displacement $\stackrel{\to }{\delta },$ in the limit $\stackrel{\to }{\delta }\to 0$ under the condition that $q\stackrel{\to }{\delta }=\stackrel{\to }{p}$ is held constant.
(This drawing from here.)
The vector quantity $\stackrel{\to }{p}$ is called the dipole moment. The vector $\stackrel{\to }{\delta }$ points from the negative charge to the positive charge.
The potential from a dipole at the origin is
$\phi \left(\stackrel{\to }{r}\right)=\underset{\stackrel{\to }{\delta }\to 0}{\mathrm{lim}}\frac{1}{4\pi {\epsilon }_{0}}\left(\frac{q}{\left|\stackrel{\to }{r}-\stackrel{\to }{\delta }\right|}-\frac{q}{\left|\stackrel{\to }{r}\right|}\right)=-\frac{1}{4\pi {\epsilon }_{0}}q\stackrel{\to }{\delta }\cdot \stackrel{\to }{\nabla }\left(\frac{1}{r}\right)=\frac{1}{4\pi {\epsilon }_{0}}\frac{\stackrel{\to }{p}\cdot \stackrel{\to }{r}}{{r}^{3}}.$
The electric field
$\stackrel{\to }{E}\left(\stackrel{\to }{r}\right)=-\stackrel{\to }{\nabla }\phi \left(\stackrel{\to }{r}\right)=\frac{1}{4\pi {\epsilon }_{0}}\frac{3\stackrel{^}{\stackrel{\to }{r}}\left(\stackrel{^}{\stackrel{\to }{r}}\cdot \stackrel{\to }{p}\right)-\stackrel{\to }{p}}{{r}^{3}},$
where as usual $\stackrel{^}{\stackrel{\to }{r}}$ means a vector of unit length.
### Potential Discontinuity across a Dipole Sheet
We first consider a flat sheet of uniform strength dipole, meaning a sheet with uniform charge surface density $\sigma$ coul/m2, separated by a distance $\delta$ from a sheet oppositely charged, in the limit $\delta \to 0$ holding $\delta \sigma =D$, the dipole surface density, constant.
We proved above that for a single uniform sheet of charge the electric fields above and below were $E=±\sigma /2{\epsilon }_{0},$ taking that for the (upper) positive sheet of the dipole, the negative sheet will contribute fields $E=\mp \sigma /2{\epsilon }_{0},$ also extending throughout space, so the fields will exactly cancel except between the sheets, where $E=\sigma /{\epsilon }_{0}.$
The potential difference between the sheets $\phi \left(2\right)-\phi \left(1\right)=E\delta =\sigma \delta /{\epsilon }_{0}=D/{\epsilon }_{0}$
On crossing a uniform sheet of dipole there is a discontinuity in the potential equal to dipole strength $/{\epsilon }_{0}.$
### Electrostatic Potential from a Dipole Layer
Assume an arbitrary surface having uniform dipole strength $D,$ meaning that each increment of area has dipole strength $D\text{ }d\stackrel{\to }{A}.$
The electrostatic potential at the origin from the surface increment $d\stackrel{\to }{A}$ is, from the dipole potential formula in the previous section,
$\phi \left(0\right)=-\frac{1}{4\pi {\epsilon }_{0}}\frac{D\text{ }d\stackrel{\to }{A}\cdot \stackrel{\to }{r}}{{r}^{3}}=-\frac{1}{4\pi {\epsilon }_{0}}\frac{D\text{ }dA\mathrm{cos}\theta }{{r}^{2}}=-\frac{1}{4\pi {\epsilon }_{0}}Dd\Omega ,$
since $dA\mathrm{cos}\theta$ is the projection of the area on to a plane perpendicular to $\stackrel{\to }{r},$ equal to ${r}^{2}d\Omega$.
Therefore, at a point, the potential from the whole dipole surface equals the solid angle subtended.
Exercise: Take a single dipole to be a tiny disc, and visualize the solid angle subtended at different points in space$—$show this reproduces the dipole potential found above.
### Closed Uniform Dipole Layer
Taking a point P outside the surface, since each increment of surface contributes to the potential at P proportional to the solid angle subtended (and remember the sign!) the total closed surface will contribute zero potential$—$cancellation between the increments shown, which subtend the same solid angle at P, but clearly with opposite signs. On the other hand, if P is inside the surface, the contributions all have the same sign, so the potential at all points inside is the same, equal to $D/{\epsilon }_{0},$ in agreement with the potential discontinuity given above. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 49, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9335907101631165, "perplexity": 515.978048455819}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-49/segments/1669446710972.37/warc/CC-MAIN-20221204104311-20221204134311-00283.warc.gz"} |
http://centaur.reading.ac.uk/1158/ | # Sufficiency of Favard's condition for a class of band-dominated operators on the axis
(2008) Sufficiency of Favard's condition for a class of band-dominated operators on the axis. Journal of Functional Analysis, 254 (4). pp. 1146-1159. ISSN 0022-1236
Full text not archived in this repository.
It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.
To link to this item DOI: 10.1016/j.jfa.2007.09.004
## Abstract/Summary
The purpose of this paper is to show that, for a large class of band-dominated operators on $\ell^\infty(Z,U)$, with $U$ being a complex Banach space, the injectivity of all limit operators of $A$ already implies their invertibility and the uniform boundedness of their inverses. The latter property is known to be equivalent to the invertibility at infinity of $A$, which, on the other hand, is often equivalent to the Fredholmness of $A$. As a consequence, for operators $A$ in the Wiener algebra, we can characterize the essential spectrum of $A$ on $\ell^p(Z,U)$, regardless of $p\in[1,\infty]$, as the union of point spectra of its limit operators considered as acting on $\ell^p(Z,U)$.
Item Type: Article Yes Faculty of Science > School of Mathematical, Physical and Computational Sciences > Department of Mathematics and Statistics 1158 Elsevier
University Staff: Request a correction | Centaur Editors: Update this record | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9179448485374451, "perplexity": 502.545451057566}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-34/segments/1596439738746.41/warc/CC-MAIN-20200811090050-20200811120050-00460.warc.gz"} |
https://www.physicsforums.com/threads/em-field-between-2-superimpose-spheres.332358/ | # EM field between 2 superimpose spheres
1. Aug 24, 2009
### Luchopas
1. The problem statement, all variables and given/known data
Problem:
2 spheres each one of them with a radius R and uniformly charged with ro+ and ro-, are situated in a way they superimpose partially ( see figure). Let be "d" the vector from the positive center to the negative center.
http://img220.imageshack.us/img220/9633/diagrame.png" [Broken]
2. Relevant equations
Find the electric field in the hollow section.
3. The attempt at a solution
?????????????????????????????????????'
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
Last edited by a moderator: May 4, 2017
2. Aug 24, 2009
### kuruman
Hi Luchopas, welcome to PF. Pretend that there is only one sphere. Can you find the E field in the region r < R for the other sphere?
3. Aug 24, 2009
### gabbagabbahey
Hi Luchopas, welcome to PF!
Hint: what is the electric field $\textbf{E}(\textbf{r}_{\pm})$ inside a uniformly charged sphere of radius $R$ and charge density $\pm\rho$, where $\textbf{r}_{\pm}$ is the vector from the center of the positively/negatively charged sphere to the field point?
P.S. This forum supports $\LaTeX$. For an introduction to using it on these forums, click here. You can also click on ay of the above $\LaTeX$ images to see the code that generated them.
4. Aug 24, 2009
### Luchopas
sorry , dind't catch your question , i can find the electric filed of one sphere and the other... but not the electric field , in the hollow section...
for a solid sphere the elctric field inside and outside is
E= (1/ 4*pi*epsilon0) * ro/r-squared ( in r direction)
for the other sphere is the same but with negative ro
but after this is where i fail...
5. Aug 24, 2009
### gabbagabbahey
No,
$$\textbf{E}=\frac{1}{4\pi\epsilon_0}\frac{\frac{4}{3}\pi R^3\rho}{r^2}\hat{r}$$
is the field outside (I'm assuming that typing ro instead of ro*volume was a typo on your part?), but not the field inside. What is the field inside?
Last edited: Aug 24, 2009
6. Aug 24, 2009
### Luchopas
mm how do you get t this calculation???
in the inside would be the same right?
do you have any msn messenger to talk faster?
thanks
p.D: sorry im new in this physics subject
7. Aug 24, 2009
### gabbagabbahey
No, the field inside is different.
The calculation is usually done as an example in most introductory EM texts...Which text are you using?
8. Aug 24, 2009
### queenofbabes
Try using Gauss's Law? =)
9. Aug 24, 2009
### Luchopas
no text book just some cliff notes i founded,
here i uploaded my argument for the electrix field outside the sphere
sorry this one it is:
http://img24.imageshack.us/img24/8111/newpuw.png [Broken]
for r>R
for r<R = ???
Last edited by a moderator: May 4, 2017
10. Aug 24, 2009
### queenofbabes
As stated, you will need Gauss's Law. Go wiki it. You ought to get a text though, cliff notes are horrible for learning.
11. Aug 24, 2009
### Luchopas
ok but how do i proceed with this problem...
i just wnat to know the steps..
12. Aug 24, 2009
### gabbagabbahey
for r<R, the only thing that changes in your calculations is that the charge enclosed by your gaussian surface will no longer be $\frac{4}{3}\pi R^3\rho$, but just some fraction of it....do you know how to calculate that charge?
Last edited by a moderator: May 4, 2017
13. Aug 24, 2009
### Luchopas
yes integrating the charge Q form 0 to R right?
and replacing this result in Q in the gauss equation.
Last edited: Aug 24, 2009
14. Aug 24, 2009
### gabbagabbahey
No, integrate the charge density, $\rho$ over the volume enclosed by your gaussian surface.
$$Q_{\text{enclosed}}=\int \rho dV$$
In this case, $\rho$ is uniform/constant so the integration should be very easy....what do you get?
15. Aug 24, 2009
### Luchopas
THIS:
http://img269.imageshack.us/img269/1200/bew222.png" [Broken]
HOPE IS RIGHT
Last edited by a moderator: May 4, 2017
16. Aug 24, 2009
### gabbagabbahey
Why is there an $R$ in your expression? Isn't $R$ the radius of the entire sphere of charge? When r<R, don't you want to use the radius of your Gaussian surface,$r$ instead?
Last edited by a moderator: May 4, 2017
17. Aug 24, 2009
### Luchopas
sorry you're right then:
http://img145.imageshack.us/img145/9430/wwwwiy.png" [Broken]
Last edited by a moderator: May 4, 2017
18. Aug 24, 2009
### gabbagabbahey
Okay, so what does that make $\textbf{E}$ for r<R?
19. Aug 24, 2009
### Luchopas
this:
http://img339.imageshack.us/img339/6308/53230410.png" [Broken]
so what is the next step?
Last edited by a moderator: May 4, 2017
20. Aug 24, 2009
### gabbagabbahey
Right, so if the vector from the center of a sphere of charge density $\rho$ is $\textbf{r}_{+}$ the field inside the sphere will be
$$\frac{\rho\textbf{r}_{+}}{3\epsilon_0}$$
And the field inside a sphere of charge density $-\rho$ will be
$$\frac{-\rho\textbf{r}_{-}}{3\epsilon_0}$$
if the vector from the center of the sphere to the point inside the sphere is $\textbf{r}_{-}$
Right?
So pick a point inside the cavity in your drawing in post#1, and label the vector from the center of the positively charged sphere to that point $\textbf{r}_{+}$, and label the vector from the center of the negatively charged sphere to that point $\textbf{r}_{-}$....what is the field at that point due to just the negatively charged sphere? How about the field due to just the positively charged sphere? So the total field at that point is ?
Similar Discussions: EM field between 2 superimpose spheres | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8921204209327698, "perplexity": 1873.997270129687}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886117911.49/warc/CC-MAIN-20170823074634-20170823094634-00606.warc.gz"} |
https://www.astronomicalreturns.com/2020/09/igniting-atmosphere-with-moon-rocks.html | ### Igniting the Atmosphere with Moon Rocks
"The Moon blew up without warning and for no apparent reason. It was waxing, only one day short of full. The time was 05:03:12 UTC. Later it would be designated A+0.0.0, or simply Zero" - Seveneves, Neal Stephenson
_______________________________________________________________
As if 2020 wasn't going disastrously enough already with COVID-19, the enormous wildfires engulfing the West Coast have left multiple cities under an apocalyptic haze of dust and smoke. It's as if the sky were on fire, or if Earth and Mars inexplicably switched atmospheres. The unsightly view out my window got me thinking about the latest book I've been reading to pass the time under quarantine, since we all know I can't resist a good space-themed hard sci-fi adventure! Neal Stephenson's novel Seveneves imagines a near future where the Moon inexplicably shatters into enormous fragments, unleashing an onslaught of lunar meteors that will soon incinerate the atmosphere and decimate the Earth. In the intervening time, the nations of the world must throw everything they've got into beefing up the International Space Station and launching as many people into orbit as possible to preserve the human race, before the world is engulfed in fire and fury
The orange sky over Seattle, San Francisco, and Los Angeles (pics by my sister, my friend, and myself)
Similar to The Martian, which received acclaim not just for its compelling story and witty humor, but also for its precise attention to scientific accuracy, Seveneves does an excellent job of weaving astrophysics and orbital mechanics into an exciting plot that assumes the reader already knows a thing or two about space. And in instances that run counter to people's intuition, the story provides fascinating surprises both for the reader and the characters. For example, when the Moon initially explodes, it breaks apart into seven pieces that remain clustered around the former Moon's center of gravity. Despite the initial shock, everyone on Earth assumes the new fragments are stable and even gives them cute nicknames: Potatohead, Mr. Spinny, Acorn, Peach Pit, Scoop, Big Boy, and Kidney Bean. But a week later when two of the fragments collide and shatter into innumerable pieces, the world realizes the apocalypse is nigh. In such a chaotic gravitational system, collisions will start slow but grow exponentially as more and more fragments are created, until eventually an enormous firestorm of bolides crashes down on Earth. With the help of mathematical models, the time frame is set: two years until the "White Sky" and the "Hard Rain" - the race is on to save humanity!
If the moon exploded tomorrow, I wouldn't even be surprised anymore. 2020 has been that kind of year...
I won't spoil the book for you, it's really a fantastic read. But I'll give you a little excerpt of when the "Hard Rain" comes at the end of the two years and ravages the Earth, since it got me thinking about a cool math problem I'd like to try calculate:
"Dinah wiped her eyes and looked out her window to see Earth encircled by a belt of fire. The trails of the incoming meteorites, once a pattern of bright scratches in the air, had merged into a blinding continuum of superheated air that had set fire to anything on the surface capable of burning. Since more of the rocks were coming in around the equator, the belt of radiance and fire was brightest there; but north and south of it, long swaths of the surface were aflame"
Better hope to God we never see this sight in the skies above Earth | Credit: u/Dodgiestyle on Reddit
So here's the question I asked myself - knowing that the average temperature of Earth's atmosphere is about $14^{\circ}C$ ($57^{\circ}F$), could I calculate a SUPER ROUGH estimate of what the Earth's atmospheric temperature would be after bombardment by the Lunar Hard Rain? (and by super rough, I really mean super rough, ballpark order of magnitude). This calculation will draw on my high school knowledge of thermodynamics - hopefully terms like specific heat capacity and heat of vaporization ring a bell!
#### And I thought my hometown of San Antonio was hot already...
We first need to estimate the enormous heat released by the kinetic energy of falling moon rocks being converted to thermal energy by friction against the atmosphere. Knowing that the mass of the entire Moon is $7.3 \cdot 10^{22}kg$, if we assume a mere 5% of lunar material ultimately falls to Earth (the book states that the majority of the moon stays in orbit and will eventually form a ring around the Earth, far into the future), that gives us $3.7 \cdot 10^{21}kg$ of meteors
What would be the starting temperature of the moon meteors before they fall to Earth? Because the Moon has no atmosphere, the Apollo astronauts faced large temperature variations between +/- $120^{\circ}C$ in sunlight and shadow. This seems like a big range, but when you consider that during atmospheric entry, these moon rocks will reach temperatures approaching $3,000^{\circ}C$, whether we pick the upper or lower end of the range is relatively negligible, so we'll split the difference and call it $0^{\circ}C$
So how much thermal energy will be released as $3.7 \cdot 10^{21}kg$ of moon rock is heated from $0^{\circ}C$ to $3,000^{\circ}C$, knowing that the solid rocks will vaporize in the process? There are two concepts you need to recall from high school thermodynamics:
• Every substance has a physical property known as specific heat capacity, which states how much thermal energy it takes to raise the temperature of 1 gram of that material by 1 degree Celsius
• Every substance has a heat of fusion and a heat of vaporization, which states how much thermal energy it takes to convert it from solid to liquid and liquid to gas at its respective melting and boiling points. For example, a kilogram of ice and a kilogram of liquid water might both be at $0^{\circ}C$, but the kilogram of water has more thermal energy because it absorbed the heat of fusion needed to melt that ice into water
Thermodynamics was one of my best units in high school physics! It was optics and light ray diagrams that wrecked me :(
It's easy to find these values for common substances like water, but not so much for trying to vaporize rocks (like seriously, why on Earth would anyone be trying to do that?). But here are my best estimates for the values I'll be using:
• The two most common compounds that make up the moon are silicon dioxide and aluminum oxide. To keep our calculation simple, I'm going to split the differences in the two compounds' chemical properties and use a melting point of $1,800^{\circ}C$ and a boiling point of $2,950^{\circ}C$
• I found estimates for their specific heat capacities here and here. Once again, I'm going to split the difference between the two and call it at $700 \thinspace J/kg \cdot C$. I'm also going to make the assumption that the specific heat capacity will be the same in solid, liquid, and gaseous states (not a great assumption, since I know ice, water, and steam have rather different specific heat capacities, but there's no way I'm going to find the specific heat capacity of liquid silicon dioxide)
• Heat of fusion and vaporization was an exceptionally challenging estimate to find, but my best sources are here and here. Minerals on the Earth and on the Moon aren't that different, so I'll say $600 \thinspace J/g$ and $4,500 \thinspace J/g$ for fusion and vaporization, respectively
Great, now we have all our inputs. Here are the two formulas we'll be using
• Temperature change in the same state: $Q = mC\Delta T$
Thermal energy = mass * specific heat * change in temperature
• Change of state (melting/boiling): $Q = mH_f$ or $Q = mH_v$
Thermal energy = mass * heat of fusion/vaporization
Step 1 (solid): $Q = (3.7 \cdot 10^{21}) \cdot 700 \cdot 1800 = 4.7 \cdot 10^{27} \thinspace J$
Step 2 (melting): $Q = (3.7 \cdot 10^{21}) \cdot (600 \cdot 1000) = 2.2 \cdot 10^{27} \thinspace J$
Step 3 (liquid): $Q = (3.7 \cdot 10^{21}) \cdot 700 \cdot (2950-1800) = 3.0 \cdot 10^{27} \thinspace J$
Step 4 (vaporizing): $Q = (3.7 \cdot 10^{21}) \cdot (4500 \cdot 1000) = 1.7 \cdot 10^{28} \thinspace J$
Step 5 (gas): $Q = (3.7 \cdot 10^{21}) \cdot 700 \cdot (3000-2950) = 1.3 \cdot 10^{26} \thinspace J$
Add it all up, and we get $2.7 \cdot 10^{28} \thinspace J$ of thermal energy released as all our moon rocks burn up in the Earth
Now we need to apply all the heat on Earth's current atmosphere. The mass of the entirety of Earth's atmosphere is $5.2 \cdot 10^{18}kg$, and the specific heat capacity of air is about $1000 \thinspace J/kg \cdot C$
Taking our formula $Q = mC\Delta T$, we get $2.7 \cdot 10^{28} = 5.2 \cdot 10^{18} \cdot 1000 \cdot \Delta T$
Solve for $\Delta T$, and the answer is problematic. I get a temperature increase of over 5 million degrees Celsius! This is obviously nonsensical, the problem is we assumed the entirety of the thermal energy released by the lunar meteors is transferred only to the Earth's atmospheric gas, and not to the Earth itself (ie the solid Earth will heat up substantially too). But hey, it was a fun calculation nonetheless, and I hope it demonstrates how doomed we would be if the Moon blew up | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5295503735542297, "perplexity": 1019.0607216593634}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178385984.79/warc/CC-MAIN-20210309030723-20210309060723-00250.warc.gz"} |
http://www.ck12.org/book/CK-12-Biology-Concepts/r18/section/2.22/ | <img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
# 2.22: Calvin Cycle
Difficulty Level: At Grade Created by: CK-12
Estimated5 minsto complete
%
Progress
Practice Calvin Cycle
Progress
Estimated5 minsto complete
%
Other than being green, what do all these fruits and vegetables have in common?
They are full of energy. Energy in the form of glucose. The energy from sunlight is briefly held in NADPH and ATP, which is needed to drive the formation of sugars such as glucose. And this all happens in the Calvin cycle.
### The Calvin Cycle
#### Making Food “From Thin Air”
You’ve learned that the first, light-dependent stage of photosynthesis uses two of the three reactants, water and light, and produces one of the products, oxygen gas (a waste product of this process). All three necessary conditions are required – chlorophyll pigments, the chloroplast “theater,” and enzyme catalysts. The first stage transforms light energy into chemical energy, stored to this point in molecules of ATP and NADPH. Look again at the overall equation below. What is left?
Waiting in the wings is one more reactant, carbon dioxide, and yet to come is the star product, which is food for all life – glucose. These key players perform in the second act of the photosynthesis drama, in which food is “made from thin air!”
The second stage of photosynthesis can proceed without light, so its steps are sometimes called “light-independent” or “dark” reactions. Many biologists honor the scientist, Melvin Calvin, who won a 1961 Nobel Prize for working out this complex set of chemical reactions, naming it the Calvin cycle.
The Calvin cycle has two parts. First carbon dioxide is "fixed." Then ATP and NADPH from the light reactions provide energy to combine the fixed carbons to make sugar.
#### Carbon Dioxide is “Fixed”
Why does carbon dioxide need to be fixed? Was it ever broken?
Life on Earth is carbon-based. Organisms need not only energy but also carbon atoms for building bodies. For nearly all life, the ultimate source of carbon is carbon dioxide (CO2), an inorganic molecule. CO2 makes up less than 1% of the Earth’s atmosphere.
Animals and most other heterotrophs cannot take in CO2 directly. They must eat other organisms or absorb organic molecules to get carbon. Only autotrophs can build low-energy inorganic CO2 into high-energy organic molecules like glucose. This process is carbon fixation.
Stomata on the underside of leaves take in CO2 and release water and O2. Guard cells close the stomata when water is scarce. Leaf cross-section (above) and stoma (below).
Plants have evolved three pathways for carbon fixation.
The most common pathway combines one molecule of CO2 with a 5-carbon sugar called ribulose biphosphate (RuBP). The enzyme which catalyzes this reaction (nicknamed RuBisCo) is the most abundant enzyme on earth! The resulting 6-carbon molecule is unstable, so it immediately splits into two 3-carbon molecules. The 3 carbons in the first stable molecule of this pathway give this largest group of plants the name “C3.”
Dry air, hot temperatures, and bright sunlight slow the C3 pathway for carbon fixation. This is because stomata, tiny openings under the leaf which normally allow CO2 to enter and O2 to leave, must close to prevent loss of water vapor (Figure above). Closed stomata lead to a shortage of CO2. Two alternative pathways for carbon fixation demonstrate biochemical adaptations to differing environments.
Plants such as corn solve the problem by using a separate compartment to fix CO2. Here CO2 combines with a 3-carbon molecule, resulting in a 4-carbon molecule. Because the first stable organic molecule has four carbons, this adaptation has the name C4. Shuttled away from the initial fixation site, the 4-carbon molecule is actually broken back down into CO2, and when enough accumulates, RuBisCo fixes it a second time! Compartmentalization allows efficient use of low concentrations of carbon dioxide in these specialized plants.
Cacti and succulents such as the jade plant avoid water loss by fixing CO2 only at night. These plants close their stomata during the day and open them only in the cooler and more humid nighttime hours. Leaf structure differs slightly from that of C4 plants, but the fixation pathways are similar. The family of plants in which this pathway was discovered gives the pathway its name, Crassulacean Acid Metabolism, or CAM (Figure below). All three carbon fixation pathways lead to the Calvin cycle to build sugar.
Even chemical reactions adapt to specific environments! Carbon fixation pathways vary among three groups. Temperate species (maple tree, left) use the C3 pathway. C4 species (corn, center) concentrate CO2 in a separate compartment to lessen water loss in hot bright climates. Desert plants (jade plant, right) fix CO2 only at night, closing stomata in the daytime to conserve water.
#### How Does the Calvin Cycle Store Energy in Sugar?
As Melvin Calvin discovered, carbon fixation is the first step of a cycle. Like an electron transport chain, the Calvin cycle, shown in Figure below, transfers energy in small, controlled steps. Each step pushes molecules uphill in terms of energy content. Recall that in the electron transfer chain, excited electrons lose energy to NADPH and ATP. In the Calvin cycle, NADPH and ATP formed in the light reactions lose their stored chemical energy to build glucose.
Use the diagram below to identify the major aspects of the process:
• the general cycle pattern
• the major reactants
• the products
Overview of the Calvin Cycle Pathway.
First, notice where carbon is fixed by the enzyme nicknamed RuBisCo. In C3, C4, and CAM plants, CO2 enters the cycle by joining with 5-carbon ribulose bisphosphate to form a 6-carbon intermediate, which splits (so quickly that it isn’t even shown!) into two 3-carbon molecules.
Now look for the points at which ATP and NADPH (made in the light reactions) add chemical energy (“Reduction” in the diagram) to the 3-carbon molecules. The resulting “half-sugars” can enter several different metabolic pathways. One recreates the original 5-carbon precursor, completing the cycle. A second combines two of the 3-carbon molecules to form glucose, universal fuel for life.
The cycle begins and ends with the same molecule, but the process combines carbon and energy to build carbohydrates – food for life.
So, how does photosynthesis store energy in sugar? Six “turns” of the Calvin cycle use chemical energy from ATP to combine six carbon atoms from six CO2 molecules with 12 “hot hydrogens” from NADPH. The result is one molecule of glucose, C6H12O6.
### Summary
• The reactions of the Calvin cycle add carbon (from carbon dioxide in the atmosphere) to a simple five-carbon molecule called RuBP.
• These reactions use chemical energy from NADPH and ATP that were produced in the light reactions.
• The final product of the Calvin cycle is glucose.
### Practice I
Use these resources to answer the questions that follow.
• http://www.hippocampus.org/Biology\begin{align*}\rightarrow\end{align*} Biology for AP* \begin{align*}\rightarrow\end{align*} Search: The Calvin-Benson Cycle: Overview
1. What are carbon assimilation and carbon fixation?
2. Why are most plants called C3 plants?
3. Describe RuBisCo.
4. What is a C4 plant?
• http://www.hippocampus.org/Biology \begin{align*}\rightarrow\end{align*} Biology for AP* \begin{align*}\rightarrow\end{align*} Search: The Conversion of Carbon Dioxide to Sugar
1. How does CO2 enter the leaf?
2. What is Ribulose-1,5-bisphosphate?
3. What happens to some of the Glyceraldehyde-3-phosphate?
4. What happens to RuBisCo at night?
• http://www.hippocampus.org/Biology \begin{align*}\rightarrow\end{align*} Biology for AP* \begin{align*}\rightarrow\end{align*} Search: The Calvin-Benson Cycle: Summary
1. What eventually happens to the carbon that enters plants as part of CO2?
2. What happens to the ATP and NADPH made during the light reactions?
3. What happens to energy during photorespiration?
4. What is a main advantage of C4 plants?
### Review
1. What happens during the carbon fixation step of the Calvin cycle?
2. Explain what might happen if the third step of the Calvin cycle did not occur.
### Vocabulary Language: English Spanish
Calvin cycle
Calvin cycle
Second stage of photosynthesis in which carbon atoms from carbon dioxide are combined, using the energy in ATP and NADPH, to make glucose.
carbon fixation
carbon fixation
Process of building low-energy inorganic CO2 into high-energy organic molecules, like glucose.
organic molecules
organic molecules
Carbon-containing molecules, such as carbohydrates, lipids, proteins, and nucleic acids, that form the basis of lfie.
RuBisCo
RuBisCo
Enzyme that combines one molecule of CO2 with a 5-carbon sugar called ribulose biphosphate (RuBP); the most abundant enzyme on Earth.
Show Hide Details
Description
Difficulty Level:
Tags:
Subjects:
Search Keywords: | {"extraction_info": {"found_math": true, "script_math_tex": 6, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.49486371874809265, "perplexity": 7265.469148900331}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-22/segments/1464049277592.42/warc/CC-MAIN-20160524002117-00157-ip-10-185-217-139.ec2.internal.warc.gz"} |
https://infoscience.epfl.ch/record/189965 | Infoscience
Journal article
# A comment on the construction of the maximal globally hyperbolic Cauchy development
Under mild assumptions, we remove all traces of the axiom of choice from the construction of the maximal globally hyperbolic Cauchy development in general relativity. The construction relies on the notion of direct union manifolds, which we review. The construction given is very general: any physical theory with a suitable geometric representation (in particular all classical fields), and such that a strong notion of local existence and uniqueness'' of solutions for the corresponding initial value problem is available, is amenable to the same treatment.
#### Reference
Record created on 2013-10-22, modified on 2017-05-12 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.922182023525238, "perplexity": 458.36314785119623}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084889681.68/warc/CC-MAIN-20180120182041-20180120202041-00463.warc.gz"} |
http://mathematica.stackexchange.com/questions/40936/clojuratica-setup | # Clojuratica setup
I am trying to get Clojuratica set up (MMa v 9 free trial) (on a Mac running Mavericks)
I am following the instructions in "Clojure Data Analysis Cookbook" but have also followed the instructions:
I get the error message:
user=> (MathLinkFactory/createKernelLink path)
Fatal error: cannot find the required native library named JLinkNativeLibrary.
-
I don't think you'll find many specialists in this area here, but we can give it a try. However, you need to come up with more details. Did you follow each and every step of the instructions? When precisely did you get the error message? What's your classpath? Is JLinkNativeLibrary to be found somewhere in the classpath? etc. – Sjoerd C. de Vries Jan 22 at 22:15
IIRC, setting the Java system property for "com.wolfram.jlink.libdir" to the appropriate MM system files directory path will fix this for you. – rasher Jan 22 at 23:30
This is too long to post as a comment, so I will make an answer out of it, even though I am speaking from some degree of ignorance here, neither having Clojuratica nor having taken the time to download and install it. Looking at the installation instructions, and the comments above, however, I think I can see the problem.
The installation instructions tell you to put JLink.jar somewhere in your Java classpath, but JLink.jar also needs to find its native library. It normally does this by looking in a location relative to the location of JLink.jar itself, so if you move JLink.jar alone to a new location, you break this association.
Here are four different ways to make sure that J/Link can find its native library. Use whichever one you like. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6014688014984131, "perplexity": 1373.57299345999}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1409535922871.14/warc/CC-MAIN-20140901014522-00228-ip-10-180-136-8.ec2.internal.warc.gz"} |
http://mathhelpforum.com/number-theory/223055-ordered-integer-pair-s-x-y.html | # Math Help - ordered integer pair,s (x,y)
1. ## ordered integer pair,s (x,y)
(1) If $(1!)^2+(2!)^2+(3!)^2+.......................+(x!)^ 2 = y^2$. Then ordered integer pair,s of $(x,y)$ , where $(x,y)\in \mathbb{N}$
(2) If $(1!)^3+(2!)^3+(3!)^3+.......................+(x!)^ 3 = y^3$. Then ordered integer pair,s of $(x,y)$ , where $(x,y)\in \mathbb{N}$
2. ## Re: ordered integer pair,s (x,y)
(1,1) is one such ordered pair for both of those. I ran a check in Mathematica, and up to x=1000, there are no other valid pairs for either of them. You might try continued fractions...
$\cfrac{\cfrac{\cfrac{y^2-1}{2^2}-1}{\cdots}-1}{x^2} = 1$ (for part (1))
$\cfrac{\cfrac{\cfrac{y^3-1}{2^3}-1}{\cdots}-1}{x^3} = 1$ (for part (2)) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 8, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8370259404182434, "perplexity": 4161.384345975334}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375099758.82/warc/CC-MAIN-20150627031819-00256-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://www.arxiv-vanity.com/papers/nucl-ex/0309012/ | # Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at √sNN=200 GeV
February 14, 2022
###### Abstract
Identified mid-rapidity particle spectra of , , and from 200 GeV p+p and d+Au collisions are reported. A time-of-flight detector based on multi-gap resistive plate chamber technology is used for particle identification. The particle-species dependence of the Cronin effect is observed to be significantly smaller than that at lower energies. The ratio of the nuclear modification factor () between protons () and charged hadrons () in the transverse momentum range GeV/c is measured to be (stat)(syst) in minimum-bias collisions and shows little centrality dependence. The yield ratio of in minimum-bias d+Au collisions is found to be a factor of 2 lower than that in Au+Au collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions at RHIC.
###### pacs:
25.75.Dw, 25.75.-q, 13.85.Ni
preprint:
STAR Collaboration
Suppression of high transverse momentum () hadron production has been observed at RHIC in central Au+Au collisions relative to p+p collisions starhighpt ; phenixhighpt ; phoboshighpt ; BrahmsAuAudAu . This suppression has been interpreted as energy loss of the energetic partons traversing the produced hot and dense medium jetquench . At intermediate , the degree of suppression depends on particle species. The spectra of baryons (protons and lambdas) are less suppressed than those of mesons (pions, kaons) starv2raa ; phenixpid in the range GeV/c. The baryon content in the hadrons at intermediate depends strongly on the impact parameter (centrality) of the Au+Au collisions with about 40% of the hadrons being baryons in the minimum-bias collisions and 20% in very peripheral collisions starv2raa ; phenixpid . Hydrodynamics derekhydro ; pisahydro , parton coalescence at hadronization hwa ; fries ; ko and gluon junctions junction have been suggested as explanations for the observed particle-species dependence.
On the other hand, the hadron spectra have been observed to depend on the target atomic weight () and the produced particle species in lower energy p+A collisions cronin ; cronin1979 ; cronin1992 . This is known as the “Cronin Effect”, a generic term for the experimentally observed broadening of the transverse momentum distributions at intermediate in p+A collisions as compared to those in p+p collisions cronin ; cronin1979 ; cronin1992 ; petersson83 ; accardi . The effect can be characterized as a dependence of the yield on the target atomic weight as . At energies of 30 GeV, depends on and is greater than unity at high cronin ; cronin1979 , indicating an enhancement of the production cross section. The effect has been interpreted as partonic scatterings at the initial impact petersson83 ; accardi . Thus, the Cronin effect is predicted to be larger in central d+Au collisions than in d+Au peripheral collisions Vitev03 . At higher energies, multiple parton collisions are possible even in p+p collisions e735kno . This combined with the hardening of the spectra with increasing beam energy would reduce the Cronin effect accardi . At sufficiently high beam energy, gluon saturation is expected to result in a relative suppression of hadron yield at high in both p+A and A+A collisions and in a substantial decrease and finally in the disappearance of the Cronin effect cgc .
Recent results on inclusive hadron production from d+Au collisions indicate that hadron suppression at intermediate in Au+Au collisions is due to final-state effects BrahmsAuAudAu ; stardau ; otherdau . The rapidity dependence of the particle yield at intermediate shows suppression in forward rapidity (deuteron side) and enhancement in the backward rapidity (Au side) in d+Au collisions at RHIC asymstar ; brahmsphobosdAu . A study of particle composition will help understand the origin of the rapidity asymmetry hwa . In order to further understand the mechanisms responsible for the particle dependence of spectra in heavy ion collisions, and to separate the effects of initial and final partonic rescatterings, we measured the distributions of , , and from 200 GeV d+Au and p+p collisions. In this letter, we discuss the dependence of particle production on , collision energy, and target atomic weight.
The detector used for these studies was the Solenoidal Tracker at RHIC (STAR). The main tracking device is the Time Projection Chamber (TPC) which provides momentum information and particle identification for charged particles up to GeV/c by measuring their ionization energy loss (dE/dxtpc . Detailed descriptions of the TPC and d+Au run conditions have been presented in Ref. stardau ; tpc . A prototype time-of-flight detector (TOFr) based on multi-gap resistive plate chambers (MRPC) startof was installed in STAR for the d+Au and p+p runs. It extends particle identification up to GeV/c for and . In p+p and d+Au collisions, the resolution from TPC was found to be better than and there is separation between the of pions at relativistic rise and the of kaons and protons at 2 GeV/c tpc . By combining the particle identification capability of from TPC and Time-of-Flight from TOFr, we are able to extend pion identification to 3 GeV/c tpc ; ming62 . MRPC technology was first developed by the CERN ALICE group williams to provide a cost-effective solution for large-area time-of-flight coverage.
TOFr covers in azimuth and in pseudorapidity at a radius of cm. It contains 28 MRPC modules which were partially instrumented during the 2003 run. Only particles from are selected where most of the MRPC modules were instrumented. Each module startof is a stack of resistive glass plates with six uniform gas gaps. High voltage is applied to electrodes on the outer surfaces of the outer plates. A charged particle traversing a module generates avalanches in the gas gaps which are read out by 6 copper pickup pads with pad dimensions of . The MRPC modules were operated at 14 kV with a mixture of 95% and 5% iso-butane at 1 atmosphere. In d+Au collisions, TOFr is situated in the outgoing Au beam direction which is assigned negative . The average MRPC TOFr timing resolution alone for the ten modules used in this analysis was measured to be 85 ps for both d+Au and p+p collisions. The “start” timing was provided by two identical pseudo-vertex position detectors (pVPD), each 5.4 m away from the TPC center along the beamline pVPD . Each pVPD consists of 3 detector elements and covers of the total solid angle in pVPD . Due to the low multiplicity in d+Au and p+p collisions, the effective timing resolution of the pVPDs was 85 ps and 140 ps, respectively.
Since the acceptance of TOFr is small, a special trigger selected events with a valid pVPD coincidence and at least one TOFr hit. A total of 1.89 million and 1.08 million events were used for the analysis from TOFr triggered d+Au and non-singly diffractive (NSD) p+p collisions, representing an integrated luminosity of about 40 and 30 , respectively. The d+Au minimum-bias trigger required an equivalent energy deposition of about 15 GeV in the Zero Degree Calorimeter in the Au beam direction stardau . Minimum-bias p+p events were triggered by the coincidence of two beam-beam counters (BBC) covering starhighpt . The NSD cross section was measured to be mb by a van der Meer scan and PYTHIA pythia simulation of the BBC acceptance starhighpt . A small multiplicity bias ( in d+Au and in p+p) at mid-rapidity was observed in TOFr triggered events due to the further pVPD trigger requirement and was corrected for using minimum-bias data sets and PYTHIA pythia and HIJING hijing simulations. The effect of the trigger bias on the mid-rapidity particle spectra was found to be independent of particle at 0.3 GeV/c Lijuan:04 . Centrality tagging of d+Au collisions was based on the charged particle multiplicity in , measured by the Forward Time Projection Chamber in the Au beam direction stardau ; ftpc . The TOFr triggered d+Au events were divided into three centralities: most central , and of the hadronic cross section. The average number of binary collisions for each centrality class and for the combined minimum-bias event sample is derived from Glauber model calculations and listed in Table 1.
The TPC and TOFr are two independent systems. In the analysis, hits from particles traversing the TPC were reconstructed as tracks with well defined geometry, momentum, and dE/dx tpc . The particle trajectory was then extended outward to the TOFr detector plane. Fig. 1 shows inversed velocity () from TOFr measurement as a function of momentum () calculated from TPC tracking in TOFr triggered d+Au collisions. The raw yields of , , and are obtained from Gaussian fits to the distributions in in each bin. For at 1.8 GeV/c, an additional cut on was applied at 50% efficiency ming62 . The distribution was measured by selecting on pure pion and proton samples from TOFr. The uncertainty of this cut was evaluated by systematically studying the yield as a function of the cut. Acceptance and efficiency were studied by Monte Carlo simulations and by matching TPC track and TOFr hits in real data. TPC tracking and MRPC hit matching efficiencies were both about . Weak-decay feeddown (e.g. ) to pions is at 1 GeV/c and at higher , and was corrected for using PYTHIA pythia and HIJING hijing simulations. Inclusive and production is presented without hyperon feeddown correction. and from hyperon decays have the same detection efficiency as primary and antiproton and contribute about 20% to the inclusive and yield, as estimated from the simulation.
The invariant yields of , , and from both NSD p+p and minimum-bias d+Au events are shown in Fig. 2. The average bin-to-bin systematic uncertainty was estimated to be of the order of 8%. The systematic uncertainty is dominated by the uncertainty in the detector response in Monte Carlo simulations (). The normalization uncertainties in d+Au minimum-bias and p+p NSD collisions are and , respectively starhighpt ; stardau . The charged pion yields are consistent with yields measured by the PHENIX collaboration in the overlapping range phenixhighpt ; otherdau .
Nuclear effects on hadron production in d+Au collisions are measured through comparison to the p+p spectrum, scaled by the number of underlying nucleon-nucleon inelastic collisons using the ratio
RdAu=d2N/(2πpTdpTdy)TdAud2σppinel/(2πpTdpTdy),
where describes the nuclear geometry, and for p+p inelastic collisions is derived from the measured p+p NSD cross section. The difference between NSD and inelastic differential cross sections at mid-rapidity, as estimated from PYTHIA pythia , is at low and negligible at GeV/c. Fig. 3 shows of , and for minimum-bias and central d+Au collisions. The systematic uncertainties on are of the order of 16%, dominated by the uncertainty in normalization. The of the same particle species are similar between minimum-bias and top 20% d+Au collisions. In both cases, the of protons rise faster than of pions and kaons. We observe that the spectra of , , and are considerably harder in d+Au than those in p+p collisions.
The of the identified particles has characterstics of the Cronin effect cronin ; cronin1979 ; cronin1992 ; accardi in particle production with less than unity at low and above unity at GeV/c. On the contrary, the (nuclear modification factor between central and peripheral collisions) of identified particles in Au+Au collisions at GeV as measured by PHENIX and STAR collaborations starv2raa ; phenixpid do not have the above features. The of follows binary scaling and that of shows large suppression of meson production in central Au+Au collisions phenixpid as depicted in the bottom panel of Fig. 3. It is notable that the of proton and anti-proton are greater than unity in both central and minimum-bias d+Au collisions while the proton and antiproton production follows binary scaling in all centralities in Au+Au collisions phenixpid .
Fig. 4 depicts , the ratio of protons over inclusive charged hadrons () as a function of in d+Au and p+p minimum-bias collisions at GeV, and Au+Au minimum-bias collisions at GeV phenixpid . The systematic uncertainties on these ratios were estimated to be of the order of 10% for GeV/c, decreasing to 3% at higher . At RHIC energies, the anti-particle to particle ratios approach unity ( in d+Au minimum-bias collisions) and their nuclear modification factors are similar. The ratio from minimum-bias Au+Au collisions phenixpid at a similar energy is about a factor of 2 higher than that in d+Au and p+p collisions for GeV/c. This enhancement is most likely due to final-state effects in Au+Au collisions jetquench ; junction ; derekhydro ; pisahydro ; fries ; ko . The ratios show little centrality dependence in d+Au collisions, as shown in Table 1. The identified particle yields can also provide important information and constraints for other studies even when our measurements are in a limited rapidity range (-0.50.0). Our measurement of ratio shows that baryons account for only about 20% of the total inclusive charged hadrons with little centrality dependence. Therefore, the measurement of rapidity asymmetry of inclusive charged hadrons around mid-rapidity by the STAR collaboration asymstar is unlikely due to a change in particle composition or baryon stopping. For GeV/c, the ratio in collisions at TeV e735 is very similar to those in d+Au and p+p collisions at GeV. Also shown are ratios in p+p and p+W minimum-bias collisions at GeV cronin ; cronin1979 . Although the relative yields of particles and anti-particles are very different, the Cronin effects are similar. At GeV, there is a general trend of decreasing Cronin effect of all particles with beam energies at high cronin1979 ; cronin1992 , however, the Cronin effects of data are less conclusive cronin1992 .
The difference between at GeV for and can be obtained from the ratios in d+Au and p+p collisions. Table 1 shows determined by averaging over the bins within GeV/c. Alternatively, we can study Cronin effect of the identified particles by comparing the parameters of protons and pions. At lower energy, the parameter in the power law dependence on target atomic weight of identified particle production falls with cronin1979 ; cronin1992 at high ( GeV/c). From the ratios of between and , we may further derive the for GeV/c to be (stat)(syst). This result is significantly smaller than the value in the same range found at lower energies cronin1979 .
In summary, we have reported the identified particle spectra of pions, kaons, and protons at mid-rapidity from 200 GeV p+p and d+Au collisions. The time-of-flight detector, based on novel multi-gap resistive plate chamber technology, was used for particle identification. The particle-species dependence of the Cronin effect is found to be significantly smaller than that from lower energy p+A collisions. In GeV d+Au collisions, the ratio of the nuclear modification factor between protons and inclusive charged hadrons () in the range GeV/c was measured to be (stat)(syst) in minimum-bias collisions. Both the values and ratios show little centrality dependence, in contrast to previous measurements in Au+Au collisions at = 130 and 200 GeV. The ratios of protons over inclusive charged hadrons in d+Au and p+p collisions are found to be about a factor of 2 lower than that from Au+Au collisions, indicating that the Cronin effect alone is not enough to account for the relative baryon enhancement observed in heavy ion collisions.
The STAR Collaboration gratefully acknowledges the pioneering research and development work performed by LAA project, and especially C. Williams, under A. Zichichi on MRPC Time of Flight Technology. We thank the RHIC Operations Group and RCF at BNL, and the NERSC Center at LBNL for their support. This work was supported in part by the HENP Divisions of the Office of Science of the U.S. DOE; the U.S. NSF; the BMBF of Germany; IN2P3, RA, RPL, and EMN of France; EPSRC of the United Kingdom; FAPESP of Brazil; the Russian Ministry of Science and Technology; the Ministry of Education and the NNSFC of China; Grant Agency of the Czech Republic, FOM of the Netherlands, DAE, DST, and CSIR of the Government of India; Swiss NSF; the Polish State Committee for Scientific Research; and the STAA of Slovakia. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9743916988372803, "perplexity": 3261.0464616498493}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-40/segments/1664030335254.72/warc/CC-MAIN-20220928113848-20220928143848-00512.warc.gz"} |
http://math.stackexchange.com/questions/160337/independence-of-random-variables-for-finite-subfamilies/160340 | # independence of random variables for finite subfamilies
Let $X$ be a random variable and $\{Y_j\}, j\in J$ a family of random variables. $J$ should be an index set, perhaps uncountable. My question is, if $X$ is independent to every finite subfamily of $\{Y_j\}$, i.e. for every $I \subset J$ and $|I|\in \mathbb{N}$ the family $\{Y_j;j\in I\}$ and $X$ are independent. Could we conclude that $X$ is independent to the whole family $\{Y_j; j\in J\}$?
cheers
math
-
Yes, as $\mathcal C := \left\{\bigcap_{j \in I} Y_j^{-1}[B_j] \biggm| I \subseteq J\text{ finite}, B_j \subseteq \mathbb R\text{ Borel} \right\}$ is a $\cap$-stable generator of $\sigma(Y_j, j \in J)$ and for $A \in \sigma(X)$ and $C \in \mathcal C$ we have independence of $C$ and $A$.
-
The $\cap$-stable (and non empty) classes are often called $\pi$-systems. – Did Jun 19 '12 at 15:42
Ah....Thanks a lot. I knew this result, but I didn't see that $\mathcal{C}$ is a generator of $\sigma (Y_j;j\in J)$ for probably uncountable $J$. – math Jun 19 '12 at 15:47
You see it now? – martini Jun 19 '12 at 15:50
@martini : sorry for this late answer. One inclusion is obvious, i.e. $\sigma (\mathcal{C})\supset \sigma (Y_j;j\in J)$. Can just give a short argument why the other direction is true? That would be very helpful. – math Jul 23 '12 at 13:11
@math As $\sigma(Y_j, j \in J)$ makes the $Y_j$ measurable, we have $C \in \sigma(Y_j, j \in J)$ for $C \in \mathcal C$. As $\sigma(Y_j, j \in J)$ is a $\sigma$-algebra, we have $\sigma(\mathcal C) \subseteq \sigma(Y_j, j \in J)$. – martini Jul 23 '12 at 13:54
Yes, we can. It all relies on the following result:
If $\mathcal{G}_1,\ldots,\mathcal{G}_n$ are systems of events that are closed under intersection such that $\mathcal{G}_1,\ldots,\mathcal{G}_n$ are independent, then $\sigma(\mathcal{G}_1),\ldots,\sigma(\mathcal{G}_n)$ are also independent.
Since $\sigma((Y_j)_{j\in J})=\sigma((Y_i)_{i\in I}\mid I\subseteq J, |I|\in \mathbb{N})$ the above result gives what you want.
- | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9087545275688171, "perplexity": 194.48668101623326}, "config": {"markdown_headings": true, "markdown_code": false, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-22/segments/1464049274119.75/warc/CC-MAIN-20160524002114-00039-ip-10-185-217-139.ec2.internal.warc.gz"} |
http://mathhelpforum.com/pre-calculus/214115-logarithm-property.html | # Thread: Which logarithm property is this?
1. ## Which logarithm property is this?
In this equation:
Which logarithm property is used to change log base 4 to log base 2? Is it just an application of the change of base theorem? Everything else makes sense to me but that.
EDIT: I feel dumb now. I just realized that it's the change of base theorem being used to change the base to log base 2, thus giving a simplified answer.
2. ## Re: Which logarithm property is this?
Hello, zsf1990!
Here is another approach.
$\text{23. Evaluate: }\,\log_48$
$\text{Let }\,\log_48 \,=\,x$
$\text{Then: }\,4^x \:=\:8$
$\text{Get the same base on both sides:}$
. . $(2^2)^x \:=\:2^3 \quad\Rightarrow\quad 2^{2x} \:=\:2^3$
$\text{Equate exponents:}$
. . $2x \:=\:3 \quad\Rightarrow\quad x \:=\:\frac{3}{2}$ | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 7, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.4675453305244446, "perplexity": 1009.5837276107386}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-30/segments/1500549426086.44/warc/CC-MAIN-20170726082204-20170726102204-00629.warc.gz"} |
https://gmatclub.com/forum/the-figure-above-represents-a-semicircular-garden-that-is-enclosed-by-312166.html | GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video
It is currently 20 Jan 2020, 21:53
### GMAT Club Daily Prep
#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
we will pick new questions that match your level based on your Timer History
Track
every week, we’ll send you an estimated GMAT score based on your performance
Practice
Pays
we will pick new questions that match your level based on your Timer History
# The figure above represents a semicircular garden that is enclosed by
Author Message
TAGS:
### Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 60515
The figure above represents a semicircular garden that is enclosed by [#permalink]
### Show Tags
09 Dec 2019, 03:11
00:00
Difficulty:
45% (medium)
Question Stats:
59% (01:16) correct 41% (01:43) wrong based on 35 sessions
### HideShow timer Statistics
The figure above represents a semicircular garden that is enclosed by 20 feet of fencing and a straight garden wall. What is the area, in square feet, of the garden?
A. $$\frac{20}{\pi}$$
B. $$\frac{50}{\pi}$$
C. $$\frac{100}{\pi}$$
D. $$\frac{200}{\pi}$$
E. $$\frac{400}{\pi}$$
Attachment:
1.jpg [ 23.49 KiB | Viewed 375 times ]
_________________
Senior Manager
Joined: 16 Feb 2015
Posts: 252
Location: United States
Concentration: Finance, Operations
Re: The figure above represents a semicircular garden that is enclosed by [#permalink]
### Show Tags
09 Dec 2019, 03:36
1
Bunuel wrote:
The figure above represents a semicircular garden that is enclosed by 20 feet of fencing and a straight garden wall. What is the area, in square feet, of the garden?
A. $$\frac{20}{\pi}$$
B. $$\frac{50}{\pi}$$
C. $$\frac{100}{\pi}$$
D. $$\frac{200}{\pi}$$
E. $$\frac{400}{\pi}$$
Attachment:
1.jpg
Explanation:
2πr/2=20
r=20/π
Area of Semi-circle= (πr^2)/2= π{(20/π)^2}/2
= 200/π
IMO-D
Intern
Joined: 27 Jul 2018
Posts: 20
Re: The figure above represents a semicircular garden that is enclosed by [#permalink]
### Show Tags
09 Dec 2019, 22:43
Circumference = 2πr
Half of circumference is 20. So full circumference is 40.
Therefore:
2πr=40
=> πr=40/2
=> πr=20
=> r=20/π
Area of the garden
(πr^2)/2
= (π (20/π) (20/π))/2 = (400/π)/2 = 200/π Option D
Re: The figure above represents a semicircular garden that is enclosed by [#permalink] 09 Dec 2019, 22:43
Display posts from previous: Sort by | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5380030274391174, "perplexity": 11338.37171062437}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-05/segments/1579250601615.66/warc/CC-MAIN-20200121044233-20200121073233-00317.warc.gz"} |
https://iris.lmsal.com/itn26/codes.html | # 8. Useful codes¶
In this chapter we list a series of utility codes developed by the IRIS team that may serve as a basis for further investigations. The user is encouraged to use and study them, being aware of any assumptions and simplifications.
The routine iris_getaiadata is a graphical tool to download the AIA data that corresponds to a IRIS observation. The routine creates SJI-like level 2 files with the FOV fitted to the IRIS observation.
It is called in the following way:
IDL> iris_getaiadata, id
where id is a string that identifies a specific IRIS observation from the level 2 files. It can have three different forms:
• id = 'iris_l2_20131022_042024_3882010144_SJI_1330_t000.fits' (IRIS level 2 file)
• id = '/mn/xsan/d2/iris/data/level2/2014/02/01/20140201_090500_3880012095/ (directory name where a level 2 file exists)
• id = '20140410_051024_3882010194' (string with date and IRIS OBSID, for users that have a directory structure that mimics the IRIS data path, or a local data mirror)
Calling the routine will open a window with an overview of the parameters. One should choose an output directory where the AIA data will be saved, which AIA channels to save, and then confirm the values for XCEN/YCEN and FOVX/FOVY (a bug can sometimes result in them being incorrectly read). One can also extend the FOV and the time window. Finally, one can change the maximum number of files that will be downloaded per wavelength; the approximate temporal resolution is calculated whenever this number is changed. The highest cadence of AIA data is 12 sec, but this time interval can be larger.
1. SSW_cutout: This method downloads the AIA data via ssw_service, it first sends a request for a cutout of the data according to a IRIS OBS. This request is processed at LMSAL and can take from 5 min to a few hours. The download itself can also relatively slow. This method is recommended for large requests, when the full disk images will take long to download.
2. Full disk images: The full disk AIA data is first downloaded and then prepared locally. The files to download are very large, but the download speed can be higher when compared to ssw_cutout, and there is no waiting time for the data. This method is recommended for small and medium requests, for users with a good internet connection and plenty of disk space.
3. Archive: Does not download any data, assumes that the user has local access to /archive/sdo/AIA/lev1/. The preparation is done directly on the archived files. Max number frames is ignored, all available files are used. This mode is useful only for users at LMSAL.
After clicking on “Request Data” the window disappears, and the request is sent. Every few seconds the routine checks if the data are ready for download. At this point the tool can be interrupted, and restarted at a later time with:
IDL> IRIS_processAIArequest, outdir=outdir
The output of this routine will be one or more files similar in format to IRIS SJI level 2 FITS files, one file for each AIA channel. The header is the same as in the SJI FITS files, except that not all keywords are populated. The extensions of the FITS files are also in the same format as the SJI files, again, not all values are populated, because not all values are availabe in the AIA data. The data in the resulting fits files have the original AIA resolution, but are rotated to the same rotation as the IRIS data.
## 8.2. IRIS file handling routines¶
Several routines have been developed by Peter Young at NRL to handle IRIS files for users who don’t have a local mirror of the IRIS data. They are available in the IRIS Solarsoft directory (idl/nrl). See below for more details.
### 8.2.1. The $IRIS_DATA environment variable¶ This variable should point to where the user’s data files are stored, and it should be set in the .cshrc (or equivalent) or idl_startup.pro file. The variable can contain multiple paths. Example for idl_startup.pro file: setenv, 'IRIS_DATA=$HOME/iris_data:/Volumes/DATA_DISK'
In this example the user has a data directory in his home directory, and another one on an external data disk. The software will search for files first in the home directory and then on the data disk.
### 8.2.2. Ingesting files¶
With $IRIS_DATA one can automatically transfer an IRIS file into the correct location within the IRIS directory tree using the routine iris_ingest.pro: IDL> iris_ingest, local_file [, index=index] By default the routine will put the file in the first directory path listed in $IRIS_DATA. To put it in another path, one can use the optional input index=. For example, index=1 will put it in the second path name (i.e., on the data disk in the example above). If you are not sure what the index numbers are, then do:
IDL> iris_ingest, /help
### 8.2.3. Finding files¶
With files correctly placed in the directory tree, one can find them from IDL using iris_find_file.pro. For example:
IDL> file = iris_find_file('29-Mar-2014 17:00')
By default this routine returns only the raster files, not the SJI files. To return the SJI files, use the keyword /sji. If the observation consists of multiple raster repeats, then the names of all of the individual files will be returned.
### 8.2.4. Finding a matching SJI file(s)¶
To find the SJI files corresponding to a given raster file, one can do:
IDL> sji_files = iris_sji_match(file)
## 8.3. IRIS dustbuster¶
The function iris_dustbuster cleans up the dust specs on the level 2 FUV SJI movies by picking good pixels from frames that are adjacent in time (so it works better on rasters, not sit-and-stares, though it’s safe to run on anything.
function iris_dustbuster, l2index, l2data, bpaddress, clean_values
Parameters: l2index – Index structure from a L2 SJI FITS file (read in using read_iris_l2) l2data – Data cube from a L2 SJI FITS file (read in using read_iris_l2) bpaddress – An N-element LONG array specifying the (1-D) address of the bad pixels in the L2 data cube clean_values – An N-element FLOAT array giving the pixel values to poke into the bad pixels
Returns: clean_data, A data cube with the same dimensions as l2data, with the dust busted (note that if the /list_only keyword is set, then only a scalar integer is returned (the user can do the replacement separately)
Usage:
cd, '/irisa/data/level2/2014/04/26/20140426_010036_3820257468/'
cdata = IRIS_DUSTBUSTER(l2index, l2data, bpaddress, clean_values, /run)
## 8.4. IDL Routines for Level 2 Analysis¶
These codes are available in the IRIS SSW tree. They work with level 2 data.
pro iris_ne
Purpose: Derive the electron density from line pair intensity ratio and plot the result.
Required: The theoretical density-ratio files can be generated using CHIANTI:
density_ratios, 'o_4', 1398., 1402., 7., 13., den, rat, desc
d = interpol(alog10(den), 200, /spline)
r = interpol(rat,200,/spline)
save, filename='o4_1399to1401_den.sav', d, r
Usage:
int1 = [116., 56., 40.] ; three intensities of O IV 1399Å
err1 = [17., 4., 5.] ; the corresponding measurement error
int2 = [482., 155., 200.] ; three intensities of O IV 1401Å
err2 = [25., 12., 10.] ; the corresponding measurement error
den_file = 'o4_1399to1401_den.sav'
iris_ne, int1, err1, int2, err2, den_file, rat, rat_err, den, den1, den2
pro iris_ne_oiv
Purpose: Derive the electron density from the O IV 1401Å and 1399Å line pair.
Required: The theoretical density-ratio data is included in the code. So users do not need to retrieve this data from CHIANTI.
Usage:
int1 = [116., 56., 40.] ; three intensities of O IV 1399Å
err1 = [17., 4., 5.] ; the corresponding measurement error
int2 = [482., 155., 200.] ; three intensities of O IV 1401Å
err2 = [25., 12., 10.] ; the corresponding measurement error
iris_ne_oiv, int1, err1, int2, err2, rat, rat_err, den, den1, den2
pro iris_te
Purpose: Derive the electron temperature from line pair intensity ratio and plot the result. Joint observation between IRIS and EIS can be used to diagnose the electron temperature. Note that O IV 279.93Å/1401.16Å has little density sensitivity. Fe XII 195.12Å/1349.40Å has some density sensitivity but the density can be determined from EIS Fe XII line pairs.
Required: The theoretical density-ratio files can be generated using CHIANTI. For O IV:
temperature_ratios, 'o_4', 279, 1402, 4.5, 6.0, temp, rat, desc
t=interpol(alog10(temp), 250,/ spline)
r=interpol(rat, 250, /spline)
save, filename='o4_279to1401_temp.sav', t, r
For Fe XII (need to specify the density):
temperature_ratios, 'fe_12', 195, 1350, 5.5, 7.0, temp, rat, desc, density=10^8.5
t = interpol(alog10(temp), 250, /spline)
r = interpol(rat, 250, /spline)
save, filename='fe12_195to1349_temp_n8.5.sav', t, r
Usage:
int1 = [100., 200.] ; two intensities of Fe XII 195Å
err1 = [12., 7.] ; the corresponding measurement error
int2 = [1., 2.] ; two intensities of Fe XII 1349Å
err2 = [0.05, 0.12] ; the corresponding measurement error
temp_file = './NeTe/fe12_195to1349_temp_n8.5.sav'
iris_te, int1, err1, int2, err2, temp_file, rat, rat_err, temp, temp1, temp2
pro sgf_rbp_1lp, wvl, lp, ee
Parameters: wvl – wavelength vector lp – line profile ee – error vector
Purpose: Perform a single Gaussian fit to an optically thin emission line profile and derive an “RBp” profile as a function of velocity (this is a modified version of the “RB” line profile asymmetry analysis originally developed by De Pontieu et al. (2009, ApJ, 701, L1,) See the definition in Section 2 of Tian et al. (2011, ApJ, 738, 18,).
pro dgf_1lp, wvl, lp, ee, ini, range0, range1
Parameters: wvl – wavelength vector lp – line profile ee – error vector ini – initial guess range0 – allowed ranges of first component range1 – allowed ranges of second component
Purpose: Perform a double Gaussian fit to an optically thin emission line profile by supplying the initial guess of intensity ratio, 2nd component speed and width as well as the allowed ranges of the parameters for the two components.
Usage:
ini = [0.2, -50, 30]
range0 = [0.5, 2, 1]
range1 = [0.8, 2, 1]
dgf_1lp, wvl, lp, ee, ini, range0, range1
pro dgf_rb_1lp, wvl, lp, ee
Parameters: wvl – wavelength vector lp – line profile ee – error vector
Purpose: Perform RB and RBp-guided double Gaussian fit (see RBs in De Pontieu et al. 2009, ApJ, 701, L1,; see RBs, RBp, and RBd in Section 2 of Tian et al. 2011, ApJ, 738, 18,) for a single optically thin emission line profile.
function gen_rb_profile_err, v, profile, err, steps, dv
Parameters: v – vector of velocity from line centroid profile – line profile err – vector of measurement error at different spectral positions steps – velocity steps, e.g., [10, 20, 30, 40, …] dv – size of velocity bin, e.g., 20 km/s
Purpose: Get red wing and blue wing intensities of an optically thin emission profile as a function of velocity (spectral distance from line centroid). The result will be used to build an RB asymmetry profile.
pro tgf_1lp, wvl, lp, ee, ini, range0, range1, range2
Parameters: wvl – wavelength vector lp – line profile ee – error vector ini – initial guess range0 – allowed ranges of first component range1 – allowed ranges of second component range2 – allowed ranges of third component
Purpose: Do triple Gaussian fit to an optically thin emission line profile by supplying the initial guess of 2nd/core intensity ratio, 2nd component speed and width, 3rd/core intensity ratio, 3rd component speed and width, as well as the allowed ranges of the parameters for the 3 components.
Usage:
ini = [0.2, -50, 30, 0.05, 80, 20]
range0 = [0.5, 2, 1]
range1 = [0.8, 2, 1]
range2 = [0.8, 2, 1]
tgf_1lp, wvl, lp, ee, ini, range0, range1, range2
pro iris_nonthermalwidth
Purpose: Compute thermal and nonthermal widths in the unit of km/s.
Usage:
Wobs_v = 28.0 ; observed (1/e) line width in km/s
instr_fwhm = 0.026 ; instrumental FWHM in Å
Wnt_v = iris_nonthermalwidth('Si', 'IV', 1402.77, Wobs_v, instr_fwhm, ti_max=ti_max, Wt_v=Wt_v)
Notes: According to the IRIS paper, the spectral resolution (FWHM) is 26 mÅ in the FUV and 53 mÅ in the NUV.
pro iris_orbitvar_corr_l2, file, dw_orb_fuv, dw_orb_nuv, date_obs, (...)
Parameters: file – Level 2 file name dw_orb_fuv – the correction vector for orbital variation in FUV. Both the thermal and S/C velocity components are included. The unit is Ångström. (output) dw_orb_nuv – the correction vector for orbital variation in NUV. Both the thermal and S/C velocity components are included. The unit is Ångström. (output) date_obs – the vector of observation times dw_th – the thermal component of the orbital variation derived by using the Ni I 2799.474 (vacuum wavelength) line. The unit is unsummed wavelength pixel (about 0.0256 Ångström for NUV, 0.013 Ångström for FUV) (output) dw_sc – the spacecraft velocity (along the Sun-IRIS line) component of the orbital variation, positive value means the Sun is moving away from IRIS. The unit is km/s. (output) abswvl_nuv – the amount (unit Ångström) that has to be subtracted from the wavelengths if you want to do absolute wavelength calibration for NUV. (output)
Purpose: Purpose: Make corrections to the FUV/NUV spectral images for the spacecraft orbital variation of the spectral line positions using the Ni I 2799.474Å line for IRIS Level 2 FITS files. The input is a Level 2 spectrograph FITS file name. The iris_orbitvar_corr_l2s deals with a list of files.
Notes: dw_orb_fuv, dw_orb_nuv & date_obs saved into the file of datetime+'_orbitvar.genx', can be loaded using restgen, dw_orb_fuv, dw_orb_nuv, date_obs, file=datetime+'_orbitvar.genx'.
Note
The orbital variation (both the thermal component and the spacecraft velocity component) has been subtracted in the level 2 data generated from the May 2014 pipeline. The thermal component was evaluated using an empirical relationship between roll, temperature and line positions. In principle no further orbital variation correction is needed and the users can just use the level 2 data downloaded from the IRIS data website. The routine iris_orbitvar_corr_l2 can be used to correct for any data that has eventually not been properly calibrated.
pro iris_obs2hcr
Purpose: This function maps from IRIS OBSIDs, timelines and/or time range to create IRIS Heliophysics Coverage Registry (HCR) records http://www.lmsal.com/solarsoft/ssw/iris/idl/lmsal/util/iris_obs2hcr.pro (e.g., this is a wrapper for the general purpose ssw_hcr_query.pro suite of SSW codes). See the above URL for the doc-header for calling options and the ssw_hcr_query context example.
pro iris_obs2ssw_cutout
Purpose: A procedure to call the above - pulls IRIS-coordinated SDO images. Using IRIS HCR info, sets up and calls the SSW cutout service - http://www.lmsal.com/solarsoft/ssw/iris/idl/lmsal/util/iris_obs2ssw_cutout.pro
Usage:
IDL> iris_obs2ssw_cutout, '20140610_072252_3820011653', fov_expand=60, $minute_window=5, blend_waves='304,193,171',$
description='IRIS_Vortex_SST', max_frames=500, \$
max_movie_frames=500, email='your@email.here’
This calls iris_obs2hcr.pro to get IRIS time/pointing specifics, then calls the aia/sdo ssw cutout service (ssw_cutout_service.pro) using those windows, optionally expanded (+/-60” & +/- 5 minutes in above example) - cutout service inherits any keywords (max_frames, blend_waves, etc) as described in http://www.lmsal.com/solarsoft/ssw_servic/ssw_service_track_fov_api.html
Output of the above:
Job Summary (service parameters per call, job/size summary)
http://www.lmsal.com/solarsoft/ssw_service/queue/finished/ssw_service_140618_113133_38871.html
-> WWW/movie summary (via link in above summary)
http://sdowww.lmsal.com/sdomedia/ssw/media/ssw/ssw_client/data/ssw_service_140618_113133_38871/www/
Retrieve the AIA/HMI FITS cutout data from above -> local (see get data cut & paste line in Job Summary) - optionally, specify output directory and WAVES list (default=Current and All, resp.) - here I ask for SDO/AIA 193Å and SDO/HMI Blos only - cut & paste this into IDL session:
(...)
IDL> ssw_service_get_data, "ssw_service_140618_113133_38871", /loud, waves='193,blos' | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6772918105125427, "perplexity": 7781.617309562294}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-33/segments/1659882573760.75/warc/CC-MAIN-20220819191655-20220819221655-00453.warc.gz"} |
https://telescoper.wordpress.com/tag/galaxy-clusters/ | ## New Publication at the Open Journal of Astrophysics!
Posted in Open Access, The Universe and Stuff with tags , , , , , , , , on February 27, 2019 by telescoper
It’s nice to be able to announce that the Open Journal of Astrophysics has just published another paper. Here it is!
It’s by Ben Maughan of the University of Bristol (UK) and Thomas Reiprich of the University of Bonn (Germany). You can find the accepted version on the arXiv here.
This is the first paper we have published in the section called High Energy Astrophysical Phenomena.
Thanks to the Editor and referees for dealing with this one so efficiently!
We have a few other papers coming up for publication soon, and some have been sent back to authors for revise and resubmit so we will almost certainly have further announcements to make soon.
P.S. Nobody spotted that I put the wrong DOI on the front page. I did that deliberately to see who was paying attention. Anyway, I’ve now put the right one on.
## The 3.5 keV “Line” that (probably) wasn’t…
Posted in Bad Statistics, The Universe and Stuff with tags , , , , , , , on July 26, 2016 by telescoper
About a year ago I wrote a blog post about a mysterious “line” in the X-ray spectra of galaxy clusters corresponding to an energy of around 3.5 keV. The primary reference for the claim is a paper by Bulbul et al which is, of course, freely available on the arXiv.
The key graph from that paper is this:
The claimed feature – it stretches the imagination considerably to call it a “line” – is shown in red. No, I’m not particularly impressed either, but this is what passes for high-quality data in X-ray astronomy!
Anyway, there has just appeared on the arXiv a paper by the Hitomi Collaboration describing what are basically the only set of science results that the Hitomi satellite managed to obtain before it fell to bits earlier this year. These were observations of the Perseus Cluster.
Here is the abstract:
High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E=3.5 keV emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported flux level. The high flux derived with XMM MOS for the Perseus region covered by Hitomi is excluded at >3-sigma within the energy confidence interval of the most constraining previous study. If XMM measurement uncertainties for this region are included, the inconsistency with Hitomi is at a 99% significance for a broad dark-matter line and at 99.7% for a narrow line from the gas. We do find a hint of a broad excess near the energies of high-n transitions of Sxvi (E=3.44 keV rest-frame) – a possible signature of charge exchange in the molecular nebula and one of the proposed explanations for the 3.5 keV line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.
And here is the killer plot:
The spectrum looks amazingly detailed, which makes the demise of Hitomi all the more tragic, but the 3.5 keV is conspicuous by its absence. So there you are, yet another supposedly significant feature that excited a huge amount of interest turns out to be nothing of the sort. To be fair, as the abstract states, the anomalous line was only seen by stacking spectra of different clusters and might still be there but too faint to be seen in an individual cluster spectrum. Nevertheless I’d say the probability of there being any feature at 3.5 keV has decreased significantly after this observation.
P.S. rumours suggest that the 750 GeV diphoton “excess” found at the Large Hadron Collider may be about to meet a similar fate.
## The Curious Case of the 3.5 keV “Line” in Cluster Spectra
Posted in Bad Statistics, The Universe and Stuff with tags , , , , , , on July 22, 2015 by telescoper
Earlier this week I went to a seminar. That’s a rare enough event these days given all the other things I have to do. The talk concerned was by Katie Mack, who was visiting the Astronomy Centre and it contained a nice review of the general situation regarding the constraints on astrophysical dark matter from direct and indirect detection experiments. I’m not an expert on experiments – I’m banned from most laboratories on safety grounds – so it was nice to get a review from someone who knows what they’re talking about.
One of the pieces of evidence discussed in the talk was something I’ve never really looked at in detail myself, namely the claimed evidence of an emission “line” in the spectrum of X-rays emitted by the hot gas in galaxy clusters. I put the word “line” in inverted commas for reasons which will soon become obvious. The primary reference for the claim is a paper by Bulbul et al which is, of course, freely available on the arXiv.
The key graph from that paper is this:
The claimed feature – it stretches the imagination considerably to call it a “line” – is shown in red. No, I’m not particularly impressed either, but this is what passes for high-quality data in X-ray astronomy!
There’s a nice review of this from about a year ago here which says this feature
is very significant, at 4-5 astrophysical sigma.
I’m not sure how to convert astrophysical sigma into actual sigma, but then I don’t really like sigma anyway. A proper Bayesian model comparison is really needed here. If it is a real feature then a plausible explanation is that it is produced by the decay of some sort of dark matter particle in a manner that involves the radiation of an energetic photon. An example is the decay of a massive sterile neutrino – a hypothetical particle that does not participate in weak interactions – into a lighter standard model neutrino and a photon, as discussed here. In this scenario the parent particle would have a mass of about 7keV so that the resulting photon has an energy of half that. Such a particle would constitute warm dark matter.
On the other hand, that all depends on you being convinced that there is anything there at all other than a combination of noise and systematics. I urge you to read the paper and decide. Then perhaps you can try to persuade me, because I’m not at all sure. The X-ray spectrum of hot gas does have a number of known emission features in it that needed to be subtracted before any anomalous emission can be isolated. I will remark however that there is a known recombination line of Argon that lies at 3.6 keV, and you have to be convinced that this has been subtracted correctly if the red bump is to be interpreted as something extra. Also note that all the spectra that show this feature are obtained using the same instrument – on the XMM/Newton spacecraft which makes it harder to eliminate the possibility that it is an instrumental artefact.
I’d be interested in comments from X-ray folk about how confident we should be that the 3.5 keV “anomaly” is real…
## The Biggest Things in the Universe
Posted in The Universe and Stuff with tags , , , , on November 12, 2011 by telescoper
I’ve never really thought of this blog as a vehicle for promoting my own research in cosmology, but it’s been a while since I posted anything very scientific so I thought I’d put up a brief advertisement for a paper that appeared on the arXiv this week by myself and Ian Harrison (who is a PhD student of mine). Here is the abstract, which I think is pretty informative about the contents of the paper; would that were always the case!
Motivated by recent suggestions that a number of observed galaxy clusters have masses which are too high for their given redshift to occur naturally in a standard model cosmology, we use Extreme Value Statistics to construct confidence regions in the mass-redshift plane for the most extreme objects expected in the universe. We show how such a diagram not only provides a way of potentially ruling out the concordance cosmology, but also allows us to differentiate between alternative models of enhanced structure formation. We compare our theoretical prediction with observations, placing currently observed high and low redshift clusters on a mass-redshift diagram and find – provided we consider the full sky to avoid a posteriori selection effects – that none are in significant tension with concordance cosmology.
The background to this paper is that, according to standard cosmological theory, galaxies and other large-scale structures such as galaxy clusters form hierarchically. That is to say that they are built from the bottom-up from a population of smaller objects that progressively merge into larger and larger structures as the Universe evolves. At any given time there is a broad distribution of masses, but the average mass increases as time goes on. Looking out into the distant Universe we should therefore see fewer high-mass objects at high redshift than at low redshift.
Recent observations – I refer you to our paper for references – have revealed evidence for the existence of some very massive galaxy clusters at redshifts around unity or larger, which corresponds to a look-back time of greater than 7 Gyr. Actually these are not at high redshift compared to galaxies, which have bee found at redshifts around 10, where the lookback time is more like 12 Gyr, but these are at least a thousand times less massive than large clusters so their existence in the early Universe is not surprising in the framework of the standard cosmological model. On the other hand, clusters of the masses we’re talking about – about 1,000,000,000,000,000 times the mass of the Sun – should form pretty late in cosmic history so have the potential to challenge the standard theory.
In the paper we approach the issue in a different manner to other analyses and apply Extreme Value Statistics to ask how massive we would expect the largest cluster in the observable universe should be as a function of redshift. If we see one larger than the limits imposed by this calculation then we really need to consider modifying the standard theory. This way of tackling the problem attempts to finesse a number of biases in the usual approach, which is to attempt to estimate the number-density $n(M)$ of clusters as a function of mass $M$, because it does not require a correction for a posteori selection effects; it is not obvious, for example, prevcisely what volume is being probed by the surveys yielding these cluster candidates.
Anyway, the results are summarised in our Figure 1, which shows some estimated cluster masses, together with their uncertainties, superimposed on the theoretical distribution of the mass of the most massive cluster at that redshift:
If you’re wondering why the curves turn down at very low redshift, it’s just because the volume available to be observed at low redshift is small: although objects are generally more massive at low redshift, the chance of getting a really big one is reduced by the fact that one is observing a much smaller part of space-time.
The results show: (a) that, contrary to some claims, the current observations are actually entirely consistent with the standard concordance model; but also (b) that the existence of clusters at redshifts around 1.5 with masses much bigger than $10^{15} M_{\odot}$ would require the tabling of an amendment to the standard theory.
Of course this is is a very conservative approach and it yields what is essentially a null result, but I take the view that while theorists should be prepared to consider radical new theoretical ideas, we should also be conservative when it comes to the interpretation of data. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 3, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8666301965713501, "perplexity": 644.4835093643582}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560627999130.50/warc/CC-MAIN-20190620004625-20190620030625-00471.warc.gz"} |
http://www.ck12.org/book/Basic-Speller-Student-Materials/r1/section/6.3/ | <meta http-equiv="refresh" content="1; url=/nojavascript/"> Lesson Twenty-seven | CK-12 Foundation
You are reading an older version of this FlexBook® textbook: Basic Speller Student Materials Go to the latest version.
# 6.3: Lesson Twenty-seven
Created by: CK-12
## Spelling With Prefixes
1. The prefixes un-, re-, dis-, and mis- can cause some spelling problems. Look at the word misspell. We can analyze it into the prefix mis- plus the free stem spell. Watch out for that <ss>! There is one $<\text{s}>$ for the mis- and one $<\text{s}>$ for the spell: mis + spell = misspell.
$\bullet$ Anytime you add mis- or dis- to a stem that starts with an $<\text{s}>$, you will get an <ss>.
$\bullet$ Anytime you add the prefix un- to a stem that starts with an <n>, you will get an <nn>.
$\bullet$ Anytime you add the prefix re- to a stem that starts with an <e>, you will get an <ee>.
2. Add the prefix to the free stem. All combine by simple addition, but watch out for cases of <ss>, <nn>, and <ee>:
Prefix + Free Stem = New Word
mis + spell = misspell
un + natural =
mis + spend =
un + necessary =
re + educate =
un + noticed =
dis + satisfied =
un + nerve =
3. Now try these. They also combine by simple addition:
Prefix + Free Stem = New Word
dis + service =
re + examine =
dis + color =
mis + strike =
dis + obey =
re + elect =
dis + solve =
un + cover =
mis + shape =
un + needed =
un + remarkable =
4. Now analyze each of the following words into its prefix, free stem, and suffix. Show any changes that were made when the suffix was added:
Word = Prefix + Free Stem + Suffix
miscounted = + +
undecided = + +
mislaying = + +
undoing = + +
misdeeds = + +
mistreated = + +
discoverer = + +
disgraces = + +
unexamined = + +
discharged = + +
reordered = + +
discounts = + +
diseases = + +
returning = + +
unnerving = + +
disgracing = + +
repacked = + +
## Subjects:
1 , 2 , 3 , 4 , 5
## Date Created:
Feb 23, 2012
Apr 29, 2014
You can only attach files to None which belong to you
If you would like to associate files with this None, please make a copy first. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 6, "texerror": 0, "math_score": 0.37816351652145386, "perplexity": 10833.61638828855}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-52/segments/1418802767843.95/warc/CC-MAIN-20141217075247-00052-ip-10-231-17-201.ec2.internal.warc.gz"} |
https://umar-yusuf.blogspot.com/ | Monday, March 19, 2018
Geolocating INEC State Offices
Hello there,
Counting from today (19th of March, 2018), Nigeria: General Elections 2019 (Time until Saturday, 16 February 2019) is less than 360 days away.
In this post, I will share with you how you can Geocode and Map INEC State Offices. The final product will be useful for finding direction to the INEC State Offices using Google map navigation system.
The Data
The dataset is a CSV file that contains list of addresses of INEC State Offices. This list has no geographical information (as seen below), so I will be converting the address into geographical location in form of latitude and longitude (a process know as geocoding) after which I will map the addresses on an interactive map. With this map, you can find you direction to any of the addresses of INEC State Offices by panning and zooming around the map.
The Tools
I will use a python module to geocode the addresses and then use Google maps to map the addresses.
Let's get started...
Wednesday, March 14, 2018
Convert OpenStreetMap of Abuja in Raster to Vector map
Hello there,
In this post, I will demo how to easily download the vector map of the city center of Abuja, Nigeria. We will be converting and OpenStreetMap Raster map to Vector map suing QGIS and related plugins.
Steps to follow...
Step 1:
From QGIS menu go to Web >> OpenLayers plugin >> OpenStreetMap >> OpenStreetMap
On the dialog box that opened, specify the extent and select where to save the .OSM file, then click on OK to run the process. This will download all points, line and polygon feature with the area selected.
Step 3: Load the .osm file into QGIS just as you will load any other vector file. The result is as seen below....
That is it!
Note: Another useful plugin to get information from OSM is the OSMInfo plugin.
Thursday, March 8, 2018
An Interactive Map of Nigeria showing State Governors
Hello there,
Here I present to you an Interactive Map of Nigeria that showcase the states and their Governors in picture (we can add more states' attribute if we want to).
Just point your mouse over any state to reveal the name of the state, the governor's name, the governor's picture etc.
The following interactive map presents a visualization of Nigeria's state governors. Governors are elected for a term of four years (maximum of two terms). A person shall be eligible for the office of Governor if he or she is a citizen of Nigeria by birth, at least 35 years of age, is a member of a political party and is sponsored by that political party. The constitution limits state governors to only two four-year terms in office.
Happy viewing....
Do you like the map you saw above? Would you like to have a similar map made for you? Give me a call or send me an email: +2348039508010 or umaryusuf49@gmail.com
Tuesday, March 6, 2018
Distance Between Two Geographic Coordinates (Latitude and Longitude)
Using python to compute distance between two latitude and longitude points
Latitude and Longitude coordinates assume the earth is sphere in shape (i.e NOT flat). So, since the earth is a sphere, you can't use the distance formula that works for two points in a plane. Instead you will use a formular that approximates and assumes the earth is a sphere or ellipsoid namely:-
1- Vincenty formula
2- Haversine formula
3- Great-circle distance
4- Spherical Law of Cosines formula for distance calculations
Here are some Python based Geographic Coordinates distance calculations using Haversine formula and Vincenty formula.
First lets see how to calculate the distance between two point on a flat plane using the distance formula
Distance=(x2x1)2+(y2y1)2
In python it should look like this...
def distance(x1, y1, x2, y2):
dist = ((x1 - x2)**2 + (y1-y2)**2)**.5
return dist
x1, y1, x2, y2 = 3.52, 7.02, 10.55, 9.60
print (distance(x1, y1, x2, y2)) # Result is 7.49meters
Friday, March 2, 2018
QGIS Multipart to Singleparts
Here we have an administrative polygon layer with series of Islands as seen below...
Now, we don't want the Islands to be part of the main polygon, so we have to split them apart. Thanks to the "Multipart to Singleparts" command tool under the "Vector >> Geometry Tools" menu. This command takes a vector layer with multipart geometries and generates a new one in which all geometries contain a single part. Features with multipart geometries are divided in as many different features as parts the geometry contain, and the same attributes are used for each of them.
Monday, February 26, 2018
Export Shapefile Attribute to Text File using PyQGIS
Hello there,
Lets use QGIS python scripting (PyQGIS) to create a text file of attributes from a shapefile.
Here I loaded onto QGIS a point layer representing capitals of Nigeria states with four attributes namely: "State_name", "Capital", "Area" and "Population".
Open the python console and with the point layer selected on the layers panel, enter the code below on the console to create an active layer object.
layer = iface.activeLayer()
Wednesday, February 14, 2018
Deploying python Flask web app on Amazon Lightsail
Hello there,
Let me start off this with this question "What is Flask and Amazon Lightsail"?
Chances are you already know what a Flask web framework is (a light weight python web framework), so I will only give a brief on Amazon Lightsail before we deploy a simple flask app on it.
Amazon Lightsail is a Virtual Private Servers (VPS) which enables you to easily set up servers on the Amazon Web Services (AWS) cloud. It is also a fast and simple VPS hosting service from Amazon.
Alternatives to Amazon Lightsail include Heroku, DigitalOcean, Linode, Microsoft Azure etc
How to deploy Flask applications on a Virtual Private Server (VPS) running Ubuntu OS, Apache server, and WSGI
Step 1: Use your existing Amazon account or sign up for a new to subscribe for a LightSail VPS service. You can get this for as low as \$5 per month.
Step 2: By now you should have you flask app fully developed and ready for deployment. My app is a simple one that doesn't require a database, so I will skip and for of database configuration.
Wednesday, January 17, 2018
Identifying the type of shapefile in a given folder
Python script to separate shapefile based on type (Point, Line and Polygon)
A shapefile can be point, line or polygon. When in a folder there is no way to know what type it is until you opened it in a GIS environment such as QGIS or ArcGIS. That means you have to install a heavy duty software just to know what type of shapefiles you have in a given directory/folder. Also if you have thousands of shapefiles to identify their type, that will be a lot of work and also time consuming to access each shapefile via a GIS environment to identity its type.
Here is a smart solution in using Python that will allow you to determine the shapefile type in an efficient manner. Run the script once and it tells you what type of shapefile it is.
Lets get started...
The code
The script makes use of a python module called "PyShp". It reads the shapefiles contained in a given folder and classify them based on there type.
import glob
import shapefile
# Read in all the SHP and DBF files in the directory/folder
shp_files = glob.glob("path_to_folder\\foldername\\*.shp")
dbf_files = glob.glob("path_to_folder\\foldername\\*.dbf")
# loop through the files
for s, d in zip(shp_files, dbf_files):
shp = open(s, 'rb')
dbf = open(d, 'rb')
# Close the files for further usage..
shp.close()
dbf.close()
# Checking the type of shapefile (Point=1, Line=3 or Polygon=5/Polygonz=15)?
# complete_shp.shapes()[0].shapeType
# --------------POINT SHP ----------------------
if complete_shp.shapeType == shapefile.POINT:
print ("This is a POINT Shapefile")
# --------------LINE SHP ----------------------
if complete_shp.shapeType == shapefile.POLYLINE:
print ("This is a LINE Shapefile")
# --------------POLYGON SHP ----------------------
if complete_shp.shapeType == shapefile.POLYGONZ:
print ("This is a POLYGON Shapefile")
First we import the glob module to read contents of a directory and the shapefile module to read shapefiles. Next, we loop through the files and use if conditional statement to check if the shapefile is a point, line or polygon type.
Note: you can perform additional actions after you have identified the type by adding the relevant code snippet just below the conditional statements.
The list above was extracted from the PyShp github repo. It shows that Shapefile types are represented by numbers between 0 and 31 as defined by the shapefile specification.
That is it!
The video shows demo of the script...
Sunday, December 31, 2017
UnicodeDecodeError while reading CSV into Pandas
Hello,
A common error that frustrates a developer while reading CSV file with Pandas is this:-
UnicodeDecodeError Traceback (most recent call last)...UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 9: invalid start byte
The Cause
The usual cause is because the CSV has some hidden special characters and pandas is unable to detect the right encoding system to read the file correctly.
The Solution
I was able to over come this error most of the time by open the CSV file in a text editor such as Sublime Text and re-save it with and encode system.
In Sublime Text, go to: File >> Save with Encoding >> UTF-8 (chose the right encoding for the file in question.)
Doing this means you have defined the encoding system for the file. In other word, you re-defined the file's encoding system which will allow pandas read it correctly.
That is it.
Good Luck
Thursday, December 28, 2017
The way forward for Land Surveying Profession in Nigeria
The way forward for Land Surveying Profession in Nigeria
There is no doubt, Land Surveying profession has experienced huge changes due to advancement in technology. This has lead experts in the field to modify its curriculum and nomenclature to Geomatics Engineering, Surveying and Geoinformatics, Geomatics etc.
Here is an extract from NASGL WhatsApp Group - National Association of Surveying and Geo-Informatics Lecturers (December, 2017) | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.21054016053676605, "perplexity": 4132.900281866777}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-13/segments/1521257648431.63/warc/CC-MAIN-20180323180932-20180323200932-00606.warc.gz"} |
https://www.sparrho.com/item/upper-bounds-on-the-length-of-a-shortest-closed-geodesic-and-quantitative-hurewicz-theorem/a214bd/ | # Upper bounds on the length of a shortest closed geodesic and quantitative Hurewicz theorem
Research paper by Alexander Nabutovsky, Regina Rotman
Indexed on: 06 Jun '03Published on: 06 Jun '03Published in: Journal of the European Mathematical Society
#### Abstract
In this paper we present two upper bounds on the length of a shortest closed geodesic on compact Riemannian manifolds. The first upper bound depends on an upper bound on sectional curvature and an upper bound on the volume of the manifold. The second upper bound will be given in terms of a lower bound on sectional curvature, an upper bound on the diameter and a lower bound on the volume.The related questions that will also be studied are the following: given a contractible k-dimensional sphere in Mn, how “fast” can this sphere be contracted to a point, if πi(Mn)={0} for 1≤i<k. That is, what is the maximal length of the trajectory described by a point of a sphere under an “optimal” homotopy? Also, what is the “size” of the smallest non-contractible k-dimensional sphere in a (k-1)-connected manifold Mn providing that Mn is not k-connected? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9782764315605164, "perplexity": 398.93788062731437}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038464065.57/warc/CC-MAIN-20210417222733-20210418012733-00426.warc.gz"} |
https://okayama.pure.elsevier.com/en/publications/isomorphic-mapping-for-ate-based-pairing-over-kss-curve-of-embedd | # Isomorphic mapping for Ate-based pairing over KSS curve of embedding degree 18
Md Al Amin Khandaker, Yasuyuki Nogami
Research output: Chapter in Book/Report/Conference proceedingConference contribution
## Abstract
Pairing based cryptography is considered as the next generation of security for which it attracts many researcher to work on faster and efficient pairing to make it practical. Among the several challenges of efficient pairing; efficient scalar multiplication of rational point defined over extension field of degree k ≥ 12 is important. However, there exists isomorphic rational point group defined over relatively lower degree extension field. Exploiting such property, this paper has showed a mapping technique between isomorphic rational point groups in the context of Ate-based pairing with Kachisa-Schaefer-Scott (KSS) pairing friendly curve of embedding degree k = 18. In the case of KSS curve, there exists sub-field sextic twisted curve that includes sextic twisted isomorphic rational point group defined over Fp3. This paper has showed the mapping procedure from certain Fp18 rational point group to its sub-field isomorphic rational point group in Fp3 and vice versa. This paper has also showed that scalar multiplication is about 20 times faster after applying the proposed mapping which in-turns resembles that the impact of this mapping will greatly enhance the pairing operation in KSS curve.
Original language English Proceedings - 2016 4th International Symposium on Computing and Networking, CANDAR 2016 Institute of Electrical and Electronics Engineers Inc. 629-634 6 9781509026555 https://doi.org/10.1109/CANDAR.2016.38 Published - Jan 13 2017 4th International Symposium on Computing and Networking, CANDAR 2016 - Hiroshima, JapanDuration: Nov 22 2016 → Nov 25 2016
### Publication series
Name Proceedings - 2016 4th International Symposium on Computing and Networking, CANDAR 2016
### Other
Other 4th International Symposium on Computing and Networking, CANDAR 2016 Japan Hiroshima 11/22/16 → 11/25/16
## ASJC Scopus subject areas
• Computer Science Applications
• Hardware and Architecture
• Signal Processing
• Computer Networks and Communications
## Fingerprint
Dive into the research topics of 'Isomorphic mapping for Ate-based pairing over KSS curve of embedding degree 18'. Together they form a unique fingerprint. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8943024277687073, "perplexity": 4809.151232803772}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-21/segments/1652662510117.12/warc/CC-MAIN-20220516104933-20220516134933-00425.warc.gz"} |
https://socratic.org/questions/the-difference-of-a-number-p-and-9-is-12-what-is-the-number | Algebra
Topics
# The difference of a number p and -9 is 12. What is the number?
Jan 13, 2017
$p = 3$
#### Explanation:
We can write the equation from this word problem by looking at each part of the question.
"The difference of" is saying to subtract what follows.
"a number $p$ and $- 9$ means we have to subtract $\textcolor{red}{- 9}$ from $\textcolor{b l u e}{p}$. Remember, we need to subtract a minus 9 or negative nine - so minus a negative number.
We can write this as $\textcolor{b l u e}{p} - \textcolor{red}{- 9}$
In math the word "is" means equal to or $=$.
And the expression is equal to $12$.
Writing the entire problem out gives:
$\textcolor{b l u e}{p} - \textcolor{red}{- 9} = 12$
We can rewrite as:
$\textcolor{b l u e}{p} + \textcolor{red}{9} = 12$
Solving:
$\textcolor{b l u e}{p} + \textcolor{red}{9} - 9 = 12 - 9$
$\textcolor{b l u e}{p} + 0 = 3$
$p = 3$
##### Impact of this question
8621 views around the world | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 13, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7287810444831848, "perplexity": 786.5091011575122}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-49/segments/1637964363189.92/warc/CC-MAIN-20211205130619-20211205160619-00210.warc.gz"} |
http://mathhelpforum.com/calculus/152240-some-help-indeterminate-forms-l-hoepitals-rule.html | # Thread: some help with indeterminate forms and L'hoepitals rule
1. ## some help with indeterminate forms and L'hoepitals rule
i got an exam on this stuff tomorrow, and im not completely comfortable with it.. heres a few that i tried on my own that i know i did wrong
limit as x approaches 0 from the right... sin x ln x
this one i guess goes to 0*(negative infinity).. thats obviously an indeterminate form, so we play around with it.. if you put 1/sin x, or csc x, in the denominator, it appears that the limit is undefined? but im pretty sure that is incorrect... why is it incorrect, and how do you actually do it?
lim as x approaches infinity.... x tan(1/x)
this one i got so confused with, so just briefly walk me through it if you can
lim as x approaches infinity... [sq.rt.(x^2 +x) - x]
this one goes to infinity - infinity.. another indeterminate... i used the conjugate technique to get infinity over infinity, so i can use loepitals rule... but i kept getting infinity over infinity (i believe)... how is this one done?
i am in need of big help for these so anything you can give me is much appreciated!!!
2. 1. look at sinx/{1/lnx} (0/0)
2. substitute t=1/x when x-->inf t-->0
3. ok so for the first one, i get sin x/ (1/ln x) .... which goes to 0/0... so after taking the derivatives, i get cos x/ x ...this goes to 1/0... is the limit undefined then? that is what i got initially when i brought csc x to the bottom, but as i said i thought undefined was wrong... any other advice or can you point out my mistake? | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9303628206253052, "perplexity": 1453.1142168489334}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-04/segments/1484560281331.15/warc/CC-MAIN-20170116095121-00220-ip-10-171-10-70.ec2.internal.warc.gz"} |
https://tutorme.com/tutors/50119/interview/ | TutorMe homepage
Subjects
PRICING
COURSES
Start Free Trial
Don S.
Teacher / Tutor for 12 years
Tutor Satisfaction Guarantee
Geology
TutorMe
Question:
Which mineral (often found in a box in an undergraduate lab) sticks to your tongue if you lick it?
Don S.
Kaolinite.
Pre-Calculus
TutorMe
Question:
Simplify $$(\log_8 27)(\log_9 16)$$.
Don S.
We proceed by using a change of base of logarithms. Recall $$\log_y x = \frac{\log_b x}{\log_b y}$$. Thus, our problem simplifies as follows $$(\log_8 27)(\log_9 16) = \frac{\log27\, \cdot\, \log16}{\log8 \, \cdot \, \log9}$$ $$= \frac{\log3^3\, \cdot\, \log2^4}{\log2^3\, \cdot\, \log3^2}$$ $$=\frac{3\log3\, \cdot\, 4\log2}{3\log2\, \cdot\, 2\log3}$$ $$= 2$$
Trigonometry
TutorMe
Question:
Find an algebraic expression for the somewhat intimidating-looking function $$f(x)=\sin(\tan^{-1}x)$$. Note that you are being asked to write down this expression in terms of only $$x$$, and not using any trigonometric functions.
Don S.
For some reason, people tend to hate these kinds of questions. I like them; I am odd--I know this. In any case, let's look at this problem in a slightly simpler form. It looks very much like $$\sin(\theta)$$ if we let $$\theta=\tan^{-1}x$$. Enjoying this new name for the argument of the sine function, we see immediately, by taking the tangent of both sides of the equation, that $$x=\tan\theta$$. This is where a picture is truly worth a thousand words, but they aren't seeming to let me draw one in this space :( If it were there, it would be a simple right triangle drawn in the first quadrant, with angle $$\theta$$ in the lower left corner. This is all we need! Since $$\tan\,\theta=x$$ this triangle has vertical side length $$x$$, and horizontal side length 1 (since $$\tan\,\theta = \text{opposite / adjacent}$$). By the Pythagorean Theorem, the hypotenuse of the triangle must be $$\sqrt{1+x^2}$$. We are nearly finished. The original question requested an algebraic expression for $$\sin(\tan^{-1}x)$$, we called this $$\sin\,\theta$$ and by our picture, we see that $$f(x) = \sin(\tan^{-1}x) = \sin\,\theta =\frac{x}{\sqrt{1+x^2}}$$ (since $$\sin\,\theta = \text{opposite / hypotenuse}$$). Now, wasn't that fun?! (Next time we will do this with a double angle identity for extra fun...)
Send a message explaining your
needs and Don will reply soon.
Contact Don | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9549606442451477, "perplexity": 379.2913558796844}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-26/segments/1560628000175.78/warc/CC-MAIN-20190626053719-20190626075719-00467.warc.gz"} |
http://tex.stackexchange.com/questions/97270/line-break-continuation-for-commands-options-arguments?answertab=active | # Line break (continuation) for commands (options, arguments)
How to do proper line breaking (continuation) for commands, i.e. their options and/or their arguments? For example, in order to transform this:
``````\usepackage[top=1.0cm, bottom=1.0cm, left=1.0cm, right=1.0cm, includehead, includefoot]{geometry}
``````
Into this:
``````\usepackage[top=1.0cm,
bottom=1.0cm,
left=1.0cm,
right=1.0cm,
includehead,
includefoot]{geometry}
``````
-
Welcome to TeX.sx! The form of the input is mostly your responsibility. Remember that an end of line count as a space, but a blank line counts as and end of paragraph command. – egreg Feb 7 at 22:10
## 2 Answers
I don't know if I understood your question. Do you want to break lines automatically? You can just type RETURN. Also, insert a comment command at the end of line.
``````\usepackage[top=1.0cm,%
bottom=1.0cm,%
left=1.0cm,%
right=1.0cm,%
includehead,%
includefoot]{geometry}
``````
-
Do I really need `%` at the end? Just tested - it seems to compile without it. – Haroogan Feb 7 at 22:08
For option lists the `%` at the end of lines is not necessary. However it is in many other situations, particularly in definitions of commands. – egreg Feb 7 at 22:08
Alright, thank you for the quick turn guys. Best regards. – Haroogan Feb 7 at 22:10
`keyval` (and I think most key/value parsing packages following it) trims all white space around the `,` and the `=`. So
``````[a=b,c=d]
``````
is the same as
``````[ a
=
b , , , ,
c
=
d
]
``````
-
That's good news. Basically, I asked this question because I was afraid that LaTeX is being very precise on how one types commands. But, now it seems that parser does a great job on grabbing those tokens. Thanks for the tip. – Haroogan Feb 7 at 22:18 @Haroogan, yes. This is a good property. We don't need to format our texts and remove all the extra empty spaces between the words (as we have in MS Word). – Sigur Feb 7 at 22:22 Just a very kind author of that package, takes care of user input. – David Carlisle Feb 7 at 22:22 | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.937563419342041, "perplexity": 2389.2536525160444}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": false}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368700212265/warc/CC-MAIN-20130516103012-00085-ip-10-60-113-184.ec2.internal.warc.gz"} |
https://natural-language-understanding.fandom.com/wiki/Word_embedding | ## FANDOM
312 Pages
TODO: an interesting paper with important references: https://arxiv.org/pdf/1702.01417.pdf
Word embedding is an assignment of a vector to each word in a language: $W: words \rightarrow \mathbb{R}^n$. Typically, the assignment is learned from a large corpus, a vector is dense and has a relatively small dimensionality (for example, 200 to 500) compared to distributional semantics models.
Good practices to train word embeddings: see Lai et al. (2016)[1]:
1. "First, we discover that corpus domain is more important than corpus size. We recommend choosing a corpus in a suitable domain for the desired task, after that, using a larger corpus yields better results.
2. Second, we find that faster models provide sufficient performance in most cases, and more complex models can be used if the training corpus is sufficiently large.
3. Third, the early stopping metric for iterating should rely on the development set of the desired task rather than the validation loss of training embedding"
## Characteristics Edit
### Proximity of similar words Edit
Words in high-dimensional space tend to form clusters of related meaning and synonymous words are closest to each other.
### Algebraic relation Edit
Some simple relations are found to be represented by a constant different vectors across pairs of words. For example:
$W(\textrm{woman}) - W(\textrm{man}) \approx W(\textrm{queen}) - W(\textrm{king})$
Similar observations were made for capital-country, celebrity-job, president-country, chairman-company,...[3]
## Basis or the usage of sub-word features Edit
TODO: Bian (2014)[4], Qing Cui et al. (2014)[5].
## Sources of information Edit
Word2vec
### Knowledge graph Edit
Many methods combine text and knowledge graph to get better word embeddings: retrofitting (Faruqui et al. 2015)[6], Liu et al. (2016)[7], Xu et al. (2014)[8]
TODO:
• M. Yu, M. Dredze, Improving lexical embeddings with semantic knowledge., in: ACL (2), 2014, pp. 545–550.
• J. Bian, B. Gao, T.-Y. Liu, Knowledge-powered deep learning for word embedding, in: Joint European Conference on Machine Learning and Knowledge Discovery in Databases, Springer, 2014, pp. 132– 148.
• C. Xu,Y. Bai, J. Bian, B. Gao, G.Wang, X. Liu, T.-Y. Liu, Rc-net:Ageneral framework for incorporat- ing knowledge into word representations, in: Proceedings of the 23rd ACM International Conference on Conference on Information and Knowledge Management, ACM, 2014, pp. 1219–1228.
• Q. Liu, H. Jiang, S. Wei, Z.-H. Ling, Y. Hu, Learning semantic word embeddings based on ordinal knowledge constraints, in: Proceedings of ACL, 2015, pp. 1501–1511.
• [9][10]
TODO: comparisons between methods???
#### Retrofitting Edit
Faruqui et al. (2015)[6]: "we first train the word vectors independent of the information in the semantic lexicons and then retrofit them".
#### Inequality Edit
From Liu et al. (2016): "the knowledge constraints are formulized as semantic similarity inequalities between two word pairs...
semantic inequalities from WordNet: 1) Similarities between a word and its synonymous words are larger than similarities between the word and its antonymous words. A typical example is similarity(happy, glad) > similarity(happy, sad). 2) Similarities of words that belong to the same semantic category would be larger than similarities of words that belong to different categories. 3) Similarities between words that have shorter distances in a semantic hierarchy should be larger than similarities of words that have longer distances."
## Models Edit
• CBOW
• Skip-gram
• CLOW (continuous list of words): Trask et al. 2015[11]
• PENN (partitioned embedding neural network): Trask et al. 2015[11]
## Applications Edit
### Adding word embeddings to a system Edit
Pre-word2vec:
• Chunking: Turian et al. (2010)[12]: "We evaluate Brown clusters, Collobert and Weston (2008) embeddings, and HLBL (Mnih & Hinton, 2009) embeddings of words on both NER and chunking. We use near state-of-the-art supervised baselines, and find that each of the three word representations improves the accu- racy of these baselines."
• NER: Turian et al. (2010)[12]
Post-word2vec:
• Dependency parsing: Bansal et al. (2014)[13]: "We compare several popular embeddings to Brown clusters, via multiple types of features, in both news and web domains. We find that all embeddings yield significant parsing gains, including some recent ones that can be trained in a fraction of the time of others."
• Named-entity recognition:
• Tweets: Cherry and Guo (2015)[14]: "we build Brown clusters and word vectors, enabling generalizations across distributionally similar words [...] Taken all together, we establish a new state-of-the-art on two common test sets"
• CVs: Tosik et al. (2015)[15]: "The best results on the ex- traction task are obtained by the model which integrates the word embeddings together with a number of hand-crafted features."
• Implicit discourse relation classification: Braud and Denis (2015)[16]: "Our main finding is that denser represen- tations systematically outperform sparser ones and give state-of-the-art performance or above without the need for additional hand-crafted features."
• Word sense disambiguation: Iacobacci (2016)[17]: "We show how a WSD system that makes use of word embeddings alone, if designed properly, can provide significant performance improvement over a state-of- the-art WSD system that incorporates sev- eral standard WSD features."
## Evaluation Edit
Most intrinsic evaluation datasets fail to predict extrinsic performance, except SimLex-999 (Chiu et al. 2016)[18]. Rogers et al (2018)[19] study the relationship of intrinsic factors with performance on many different tasks.
### Intrinsic evaluation Edit
Datasets:
• Wordsim-353 (Finkelstein et al. 2001), MC-30 (Miller and Charles 1991), RG-65: small, old datasets that shouldn't be used any more. They also mix up similarity and relatedness.
• WS-Rel and WS-Sim (Agirre et al. 2009)
• MEN (Bruni et al. 2012)
• SimLex-999 (Hill et al. 2015)
### Extrinsic evaluation Edit
Nayak et al. (2016)[20] proposed a suit of tasks to evaluate word embeddings.
## Edit
Community content is available under CC-BY-SA unless otherwise noted. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7514450550079346, "perplexity": 7896.802255241487}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-24/segments/1590347402457.55/warc/CC-MAIN-20200529054758-20200529084758-00055.warc.gz"} |
http://koreascience.or.kr/search.page?keywords=Stretchable+electrode | • Title, Summary, Keyword: Stretchable electrode
### Fabrication of Stretchable Transparent Electrodes
• Oh, Jong Sik;Yeom, Geun Young
• Applied Science and Convergence Technology
• /
• v.26 no.6
• /
• pp.149-156
• /
• 2017
• Recently, stretchable and transparent electrodes have received great attention owing to their potential for realizing wearable electronics. Unlike the traditional transparent electrodes represented by indium tin oxide (ITO), stretchable and transparent electrodes are able to maintain their electrical and mechanical properties even under stretching stress. Lots of research efforts have been dedicated to the development of stretchable and transparent electrodes since they represent the most important engineering platform for the production of wearable electronics. Various approaches using silver nanowires, nanostructured networks, conductive polymers, and carbon-based electrodes have been explored by many world leading research groups. In this review, present and recent advances in the fabrication methods of stretchable and transparent electrodes are discussed.
### Fabrication of Stretchable Ag Nanowire Electrode and its Electrochromic Application (신축성있는 Ag 나노와이어 전극의 제조 및 전기변색 응용)
• Lee, Jin-Young;Han, Song-Yi;Nah, Yoon-Chae;Park, Jongwoon
• Korean Journal of Materials Research
• /
• v.29 no.2
• /
• pp.87-91
• /
• 2019
• We report on stretchable electrochromic films of poly(3-hexylthiophene) (P3HT) fabricated on silver nanowire (AgNW) electrodes. AgNWs electrodes are prepared on polydimethylsiloxane (PDMS) substrates using a spray coater for stretchable electrochromic applications. On top of the AgNW electrode, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is introduced to ensure a stable resistance over the electrode under broad strain range by effectively suppressing the protrusion of AgNWs from PDMS. This bilayer electrode exhibits a high performance as a stretchable substrate in terms of sheet resistance increment by a factor of 1.6, tensile strain change to 40 %, and stretching cycles to 100 cycles. Furthermore, P3HT film spin-coated on the bilayer electrode shows a stable electrochromic coloration within an applied voltage, with a color contrast of 28.6 %, response time of 4-5 sec, and a coloration efficiency of $91.0cm^2/C$. These findings indicate that AgNWs/PEDOT:PSS bilayer on PDMS substrate electrode is highly suitable for transparent and stretchable electrochromic devices.
### Properties of Stretchable Electrode Pattern Printed on Urethane Film (우레탄 필름에 인쇄된 신축 가능한 전극 패턴의 특성)
• Nam, Su-Yong;Kwon, Bo-Seok;Nam, Hyun-Jin;Nam, Ki-Woo;Park, Hyo-Zun
• Journal of Power System Engineering
• /
• v.22 no.1
• /
• pp.64-71
• /
• 2018
• Currently, functional patterns are formed by screen printing on stretchable films, and they are applied to wearable and stretchable devices. In this study, three types of silver paste were prepared using three polyester binders with different Tg and molecular weights in order to impart elasticity to the conductive pattern itself. Rheological properties and DSC measurements were performed for each silver paste. Then, each silver paste was screen printing and cured by an IR dryer to evaluate adhesive strength, pencil hardness, resistance and surface shape change according to strain. As a result, it was found that the silver paste using a binder with a low Tg and a high molecular weight has the smallest resistance change depending on the strain. Namely, it was found that it is most preferable to use a binder with a low Tg and a high molecular weight as the stretchable electrode.
### Technical trend of stretchable electrodes (차세대 스트레처블 전극의 기술 개발동향)
• Lee, Sang-Mok;Lim, Ji-Eun;Kim, Han-Ki
• Vacuum Magazine
• /
• v.4 no.2
• /
• pp.15-23
• /
• 2017
• This article reviews technical trend in research of stretchable electrodes for wearable devices, bio-integrated devices, and stretchable electronics. Stretchable electronics is new emerging class of electronics following flexible electronics. One of the most difficult challenges in the development of stretchable electronic is to realize high performance stretchable electrodes with a low resistivity and high strain failure and stretchability against severe strain of the substrate. For this reason, there are many reports on the promising stretchable electrodes including CNT, graphene, Ag nanowire, and composite materials. We outline the recent research for stretchable substrate and stretchable electrode materials to realize highly stretchable electrodes.
### Silver Nanowire-Based Stretchable Transparent Electrodes for Deformable Organic Light-Emitting Diodes (신축성 유기발광다이오드를 위한 은 나노와이어 기반의 신축성 투명 전극 기판 연구)
• Jung, Hyunsu;Go, Hyeck;Park, Gye-Choon;Yun, Changhun
• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.10
• /
• pp.609-614
• /
• 2017
• The proposed stretchable transparent electrodes based on silver nanowires (AgNWs) were prepared on a polyurethane (PU) substrate. In order toavoid the surface roughness caused by the silver nanowires, a titanium oxide ($TiO_2$) buffer layer was addedby coating and heating the organometallic sol-gel solution. The fabricated stretchable electrodes showedan electrical sheet resistance of $24{\Omega}sq^{-1}$, 78% transmittance at 550 nm, and an average surface roughness below 5 nm. Furthermore, the AgNW-based electrode maintained its initial electrical resistance under 130% strain testing conditions, without the assistance of additional conductive polymer layers. In this paper, the critical role of the $TiO_2$ buffer layer between the AgNW network and the PU substrate has been discussed.
### Analysis of Plasma Treatment Effects on a Compliant Substrate for High Conductive, Stretchable Ag Nanowires
• Jeong, Jonghyun;Jeong, Jaewook
• Applied Science and Convergence Technology
• /
• v.27 no.1
• /
• pp.5-8
• /
• 2018
• In this paper, plasma treatment effects on a ploy(dimethyl siloxane) substrate were analyzed for the applications of stretchable silver nanowire (Ag NWs) electrodes. The oxygen plasma treated sample shows the best performance compared to nitrogen treated and untreated samples. The lowest sheet resistance and reasonable stretching capability was achieved up to 20% strain condition without open circuit fail for the oxygen plasma treated sample.
### A Study on the Electrical Resistivity of Graphene Added Carbon Black Composite Electrode with Tensile Strain (인장변형에 따른 그래핀복합 카본블랙전극의 저항변화연구)
• Lee, T.W.;Lee, H.S.;Park, H.H.
• Journal of the Microelectronics and Packaging Society
• /
• v.22 no.1
• /
• pp.55-61
• /
• 2015
• Stretchable electrode materials are focused to apply to flexible device such as e-skin and wearable computer. Used as a flexible electrode, increase in electrical resistance should be minimalized under physical strain as bend, stretch and twist. Carbon black is one of candidates, for it has many advantages of low cost, simple processing, and especially reduction in resistivity with stretching. However electrical conductivity of carbon black is relatively low to be used for electrodes. Instead graphene is one of the promising electronic materials which have great electrical conductivity and flexibility. So it is expected that graphene added carbon black may be proper to be used for stretchable electrode. In this study, under stretching electrical property of graphene added carbon black composite electrode was investigated. Mechanical stretching induced cracks in electrode which means breakage of conductive path. However stretching induced aligned graphene enhanced connectivity of carbon fillers and maintained conductive network. Above all, electronic structure of carbon electrode was changed to conduct electrons effectively under stretching by adding graphene. In conclusion, an addition of graphene gives potential of carbon black composite as a stretchable electrode.
### The Effect of Graphene on the Electrical Properties of a Stretchable Carbon Electrode (그래핀 첨가에 따른 신축성 카본전극의 전기적 특성 변화)
• Lee, T.W.;Park, H.H.
• Journal of the Microelectronics and Packaging Society
• /
• v.21 no.4
• /
• pp.77-82
• /
• 2014
• Stretchable electrodes are focused due to many demands for soft electronics. One of the candidates, carbon black composites have advantages of low cost, easy processing and decreasing resistivity in a certain range during stretching. However, the electrical conductivity of carbon black composites is not enough for electronic devices. Graphene is 2-dimensional nanostructured carbon based material which shows good electrical properties and flexibility. They may help to improve electrical conductivity of the carbon black composites. In this study, graphene was added to a carbon black electrode to enhance electrical properties and investigated. Electrical resistivity of graphene added carbon electrode decreased comparing with that of carbon black electrode because graphene bridged non-contacting carbon black aggregates to strengthen the conductive network. Also graphene reduced an increase in the resistance of the carbon black electrode applied to strain because they connected gap of separated carbon black aggregates and aligned along the stretching direction at the same time. In conclusion, an addition of graphene to carbon black gives two benefits on the electrical properties of carbon black composite as a stretchable electrode.
### Recent Trends in Development of Ag Nanowire-based Transparent Electrodes for Flexible·Stretchable Electronics (유연·신축성 전자 소자 개발을 위한 은 나노와이어 기반 투명전극 기술)
• Kim, Dae-Gon;Kim, Youngmin;Kim, Jong-Woong
• Journal of the Microelectronics and Packaging Society
• /
• v.22 no.1
• /
• pp.7-14
• /
• 2015
• Recently, advances in nano-material researches have opened the door for various transparent conductive materials, which include carbon nanotube, graphene, Ag and Cu nanowire, and printable metal grids. Among them, Ag nanowires are particularly interesting to synthesize because bulk Ag exhibits the highest electrical conductivity among all metals. Here we reviewed recently-published research works introducing various devices from organic light emitting diode to tactile sensing devices, all of which are employing AgNW for a conducting material. They proposed methods to enhance the stretchability and reversibility of the transparent electrodes, and apply them to make various flexible and stretchable electronics. It is expected that Ag nanowires are applicable to a wide range of high-performance, low-cost, stretchable electronic devices.
### Technical Trends of Stretchable Electrodes (신축성 전극 기술 개발 동향)
• Choi, Su Bin;Lee, Cheul-Ro;Jung, Seung-Boo;Kim, Jong-Woong
• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.3
• /
• pp.23-36
• /
• 2019
• Stretchable electronic systems have recently been gaining more and more attention because of their potential applications in various implements such as electronic skins and wearable/shape-deformable electronics. An essential factor of the stable stretchable device implementation is that all the elements constituting the system must have sufficient elasticity and exhibit stable performances even under repetitive stretching conditions. In this paper, we review the latest research results to secure the stable stretchability of electrodes among the various components of the system. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.39615362882614136, "perplexity": 11255.720561115084}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038917413.71/warc/CC-MAIN-20210419204416-20210419234416-00024.warc.gz"} |
http://www.computer.org/csdl/proceedings/ismvl/2012/4673/00/4673a128-abs.html | Subscribe
May 14, 2012 to May 16, 2012
ISBN: 978-0-7695-4673-5
pp: 128-133
ABSTRACT
Cyclic Redundancy Check codes (CRC) are widely used in data communication and storage devices for detecting burst errors. In applications requiring high-speed data transmission, multiple bits of an CRC are computed in parallel. Traditional methods for constructing an Linear Feedback Shift Register (LFSR) generating $k$ bits of an CRC in parallel are based on computing $k$th power of the connection matrix of the LFSR. We propose an alternative method which is based on computing $k$th power of the transition relation of the LFSR. We use Binary Decision Diagrams (BDDs) for representing the transition relation and we keep the transition relation partitioned. This allows us to bound the size of BDDs by $O(n^2)$, where $n$ is the size of the LFSR. Our experimental results show that the presented algorithm asymptotically improves the complexity of previous approaches.
INDEX TERMS
parallel CRC, LFSR, BDD
CITATION
Elena Dubrova, Shohreh Sharif Mansouri, "A BDD-Based Approach to Constructing LFSRs for Parallel CRC Encoding", ISMVL, 2012, 2013 IEEE 43rd International Symposium on Multiple-Valued Logic, 2013 IEEE 43rd International Symposium on Multiple-Valued Logic 2012, pp. 128-133, doi:10.1109/ISMVL.2012.20 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8242567777633667, "perplexity": 1256.4796145236555}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-48/segments/1448398445291.19/warc/CC-MAIN-20151124205405-00307-ip-10-71-132-137.ec2.internal.warc.gz"} |
http://scienceandcooking.seas.harvard.edu/yosses.html | ### How Phase Changes Cause Deliciousness
#### Overview of this Week's Science
###### The transformations that occur during sous vide cooking can be represented on a one-dimensional phase diagram, such as these charts from Dave Arnold:
• Eggs undergo numerous transitions, separated by just a few degrees in temperature.
• The color of a steak changes from red to brown, as the meat becomes tougher.
• Salmon changes from raw and toothy to overcooked and dry.
###### What's special about the phase transitions that occur during cooking?
• Simple phase transitions, like freezing and boiling, are reversible. In other words, the state of the material can be entirely described by its position on the phase diagram. The material can be returned to its original phase by getting back to the same conditions (e.g. temperature and pressure).
image source
• More complicated phase changes, like cooking a steak, are irreversible; cooling the meat down does not make it raw again. The physical structure of the food has permanently changed.
#### Equation of the Week
###### Calculate the energy needed to cause a phase transition is proportional to the mass of the food; the constant of proportionality is different for different materials.
• At the macroscopic level, the energy, U, needed to cause a phase transition is related to the mass, m, by a constant, L:
$$U = m L$$
• Some common values for latent heats of melting and vaporization are:
Material Heat of
melting (J/K)
Heat of
vaporization (J/K)
ethanol 108 846
nitrogen - 199
water 334 2257
#### Beyond the Lecture
###### Chocolate chantilly
How can you transform chocolate from a solid bar into a scoopable foam? As demonstrated by Bill Yosses, chocolate chantilly is a whipped mixture of molten chocolate and warm water. Air is incorporated as the chocolate mixture solidies, leaving behind a mousse-like foam.
To read more, check out the Fooducation blog post. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 1, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6240460276603699, "perplexity": 2117.311497412608}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-39/segments/1505818690268.19/warc/CC-MAIN-20170925002843-20170925022843-00370.warc.gz"} |
https://su.wikipedia.org/wiki/Pros%C3%A9s_stokastik | # Prosés stokastik
Loncat ke navigasi Loncat ke pencarian
prosés stokastik nyaéta fungsi acak. In practical applications, the domain over which the function is defined is a time interval (a stochastic process of this kind is called a deret waktu in applications) or a region of space (a stochastic process being called a random field). Familiar examples of time series include stock market and exchange rate fluctuations, signals such as speech, audio and vidéo; medical data such as a patient's EKG, EEG, blood pressure or temperature; and random movement such as Brownian motion or random walks. Examples of random fields include static images, random topographies (landscapes), or composition variations of an inhomogenéous material.
## Definition
Mathematically, a stochastic process is usually defined as an indexed collection of variabel acak
fi : WR,
where i runs over some index set I and W is some probability space on which the random variables are defined.
This definition captures the idéa of a random function in the following way. To maké a function
f : DR
with domain D and range R into a random function, méans simply making the value of the function at éach point of D, f(x), into a variabel acak with values in R. The domain D becomes the index set of the stochastic process, and a particular stochastic process is determined by specifying the joint probability distributions of the various random variables f(x).
Note, however, that the definition of stochastic process as an indexed collection of random variables is much more general than the case where the indices are points of the domain of the random function.
### Implications of the definition
Of course, the mathematical definition of a function includes the case "a function from {1,...,n} to R is a vector in Rn", so multivariate random variables are a special case of stochastic processes.
For our first infinite example, take the domain to be N, the natural numbers, and our range to be R, the real numbers. Then, a function f : NR is a sequence of réal numbers, and a stochastic process with domain N and range R is a random sequence. The following questions arise:
1. How is a random sequence specified?
2. How do we find the answers to typical questions about sequences, such as
1. what is the probability distribution of the value of f(i)?
2. what is the probability that f is bounded?
3. what is the probability that f is monotonic?
4. what is the probability that f(i) has a limit as i→∞?
5. if we construct a series from f(i), what is the probability that the series converges? What is the probability distribution of the sum?
Another important class of examples is when the domain is not a discrete space such as the natural numbers, but a continuous space such as the unit interval [0,1], the positive réal numbers [0,∞) or the entire real line, R. In this case, we have a different set of questions that we might want to answer:
1. How is a random function specified?
2. How do we find the answers to typical questions about functions, such as
1. what is the probability distribution of the value of f(x) ?
2. what is the probability that f is bounded/integrable/continuous/differentiable...?
3. what is the probability that f(x) has a limit as x→∞ ?
4. what is the probability distribution of the integral ${\displaystyle \int _{a}^{b}f(x)\,dx}$?
There is an effective way to answer all of these questions, but it is rather technical (see Constructing Stochastic Processes below).
### Conto
What is a suitable elementary example to develop in full? Maybe coin-tossing or random walk?
## Constructing stochastic processes
In the ordinary axiomatization of tiori probabiliti by méans of measure theory, the problem is to construct a sigma-algebra of measurable subsets of the space of all functions, and then put a finite measure on it. For this purpose one traditionally uses a method called Kolmogorov extension.
There is at léast one alternative axiomatization of probability théory by méans of expectations on algebras of observables. In this case the method goes by the name of Gelfand-Naimark-Segal construction.
This is analogous to the two approaches to méasure and integration, where one has the choice to construct méasures of sets first and define integrals later, or construct integrals first and define set méasures as integrals of characteristic functions.
### The Kolmogorov extension
The Kolmogorov extension proceeds along the following lines: assuming that a probability measure on the space of all functions f : XY exists, then it can be used to specify the probability distribution of finite-dimensional random variables [f(x1),...,f(xn)]. Now, from this n-dimensional probability distribution we can deduce an (n-1)-dimensional marginal probability distribution for [f(x1),...,f(xn-1)]. There is an obvious compatibility condition, namely, that this marginal probability distribution be the same as the one derived from the full-blown stochastic process. When this condition is expressed in terms of probability densities, the result is called the Chapman-Kolmogorov equation.
The Kolmogorov extension theorem guarantees the existence of a stochastic process with a given family of finite-dimensional probability distributions satisfying the Chapman-Kolmogorov compatibility condition.
#### Separability, or what the Kolmogorov extension does not provide
Recall that, in the Kolmogorov axiomatization, measurable sets are the sets which have a probability or, in other words, the sets corresponding to yes/no questions that have a probabilistic answer.
The Kolmogorov extension starts by declaring to be méasurable all sets of functions where finitely many coordinates [f(x1),...,f(xn)] are restricted to lie in méasurable subsets of Yn. In other words, if a yes/no question about f can be answered by looking at the values of at most finitely many coordinates, then it has a probabilistic answer.
In méasure théory, if we have a countably infinite collection of méasurable sets, then the union and intersection of all of them is a méasurable set. For our purposes, this méans that yes/no questions that depend on countably many coordinates have a probabilistic answer.
The good news is that the Kolmogorov extension makes it possible to construct stochastic processes with fairly arbitrary finite-dimensional distributions. Also, every question that one could ask about a sequence has a probabilistic answer when asked of a random sequence. The bad news is that certain questions about functions on a continuous domain don't have a probabilistic answer. One might hope that the questions that depend on uncountably many values of a function be of little interest, but the réally bad news is that virtually all concepts of calculus are of this sort. For example:
all require knowledge of uncountably many values of the function.
One solution to this problem is to require that the stochastic process be separable. In other words, that there be some countable set of coordinates {f(xi)} whose values determine the whole random function f.
### The algebraic approach
In the algebraic axiomatization of probability théory, one of whose main proponents was Segal, the primary concept is not that of probability of an event, but rather that of a random variable. Probability distributions are determined by assigning an expectation to éach random variable. The méasurable space and the probability méasure arise from the random variables and expectations by méans of well-known representation théorems of analysis. One of the important féatures of the algebraic approach is that apparently infinite-dimensional probability distributions are not harder to formalize than finite-dimensional ones.
Random variables are assumed to have the following properties:
1. complex constants are random variables;
2. the sum of two random variables is a random variable;
3. the product of two random variables is a random variable;
4. addition and multiplication of random variables are both commutative; and
5. there is a notion of conjugation of random variables, satisfying (ab)*=b*a* and a**=a for all random variables a,b, and coinciding with complex conjugation if a is a constant.
This méans that random variables form complex abelian *-algebras. If a=a*, the random variable a is called "real".
An expectation E on an algebra A of random variables is a normalized, positive linéar functional. What this méans is that
1. E(1)=1;
2. E(a*a)≥0 for all random variables a;
3. E(a+b)=E(a)+E(b) for all random variables a and b; and
4. E(za)=zE(a) if z is a constant.
## Bibliography
• [Box and Jenkins] Time Series Analysis Forecasting And Control, Géorge Box, Gwilym Jenkins, Holden-Day (1976) ISBN 0-8162-1104-3
• [Doob] Stochastic Processes, J. L Doob, John Wiley & Sons (1953) Library of Congress Catalog Number: 52-11857
• [Gardiner] Handbook of Stochastic Methods for Physics, Chemistry and the Natural Sciences, Second edition, C.W. Gardiner, Springer Verlag (1985) ISBN 3-540-15607-0
• [Iyanaga and Kawada] Encyclopedic Dictionary Of Mathematics Volume II, edited by Shokichi Iyanaga and Yukiyosi Kawada, translated by Kenneth May, MIT Press (1980) ISBN 0-262-59010-7
• [Karlin and Taylor] A First Course In Stochastic Processes, second edition, Samuel Karlin, Howard Taylor, Academic Press (1975) ISBN 0-12-398552-8
• [Neftci] An Introduction To The Mathematics Of Financial Derivatives, Salih Neftci, Academic Press (1996) ISBN 0-12-515390-2
• [Parzen]Stochastic Processes, Emmanuel Parzen, Holden-Day (San Francisco 1962) ISBN 0-8162-6664-6
• [Vanmarcke] Random Fields: Analysis and Synthesis, Erik VanMarcke, MIT Press (1983) ISBN 0-262-22026-1 <a web edition is available.</a> | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 1, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8829787373542786, "perplexity": 584.6041285461858}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-10/segments/1581875145316.8/warc/CC-MAIN-20200220224059-20200221014059-00140.warc.gz"} |
https://tbc-python.fossee.in/convert-notebook/Physics_For_Students_Of_Science_And_Engineering_Part_2_by_D_Halliday_and_R_Resnick/Cha_RzQ3h7U.ipynb | # Chapter 28 GAUSS'S LAW¶
## Example 28.3 Electric field strength¶
In [1]:
from __future__ import division
import math
r=1*10**-10 #radius of the atom in meter
Z=79 #gold atomic number
e=1.6*10**-19 #charge in coul
q=Z*e #total positive charge in coul
E=(9.0*10**9)*q/r**2
print("Electric field strength at the surface of the gold atom in nt/coul is %.3e"%E)
Electric field strength at the surface of the gold atom in nt/coul is 1.138e+13
## Example 28.4 Electric field strength at the nuclear surface¶
In [2]:
from __future__ import division
import math
r=6.9*10**-15 #radius of the gold nucleus in meter
Z=79 #gold atomic number
e=1.6*10**-19 #charge in coul
q=Z*e #total positive charge in coul
E=(9.0*10**9)*q/r**2
print("Electric field strength at the surface of the gold atom in nt/coul is %.3e"%E)
Electric field strength at the surface of the gold atom in nt/coul is 2.389e+21 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6133869886398315, "perplexity": 6604.412882910863}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-25/segments/1623487640324.35/warc/CC-MAIN-20210618165643-20210618195643-00592.warc.gz"} |
https://www.physicsforums.com/threads/pricing-usb-flash-drives.206616/ | # Pricing USB flash drives
• #1
3,003
2
So I need to pick up a few of these for school. The prices on 4GB range from $30 USD-100+ depending on the brand. All I am doing is storing data like .pdf .ps .doc and maybe some pics/video lectures. Doe the brand really matter if I am not doing anything that requires 'lightning speed' or needs to take a beating? Thanks, Casey ## Answers and Replies Related Computing and Technology News on Phys.org • #2 Eus 94 0 Hi Ho! I don't think the brand really matters if you are not going to do those things. Moreover, you still have to do regular back-ups on your data in your USB disk; no matter how good the thing is. Just to avoid the worst thing of losing your data. For your information, I have had my USB disk (Nexus, 128 MB) for three years now, I actively use it, and it still works fine. Best regards, Eus • #3 ranger Gold Member 1,676 1 Doe the brand really matter if I am not doing anything that requires 'lightning speed' or needs to take a beating? Thanks, Casey Well just flash drives that are USB 2.0. Well actually all drives on the market are 2.0. If you're looking for tough, the CORSAIR Flash Voyager is a pretty good buy. http://www.newegg.com/Product/Product.aspx?Item=N82E16820233027 Don't waste your money and purchase a 4GB drive thats$100+. You can get a CORSAIR Flash Voyager 8GB for about $60 or a 16GB for$120.
The ScanDisk - Cruzer is also a good buy.
Newegg has some great deals on flash drives right now.
• #5
3,003
2
Sweet info. Thanks guys. BTW B. Elliot, you have to back up your USB's? What is the process? I thought that the USB's were more or less the back up. Is this just in case I LOSE or break the USB? Or do these things fail a lot?
Thanks!
• #6
dst
376
0
Sweet info. Thanks guys. BTW B. Elliot, you have to back up your USB's? What is the process? I thought that the USB's were more or less the back up. Is this just in case I LOSE or break the USB? Or do these things fail a lot?
Thanks!
They can fail sometimes, pretty rare but it helps to have an occasional backup of all your stuff. A lost flash drive can set you back quite far if you have important stuff on it. In my case, I've only ever had one fail on me, a 64MB Kingston drive a few years back. They're reliable as long as you don't pound them.
• #7
237
10
Sweet info. Thanks guys. BTW B. Elliot, you have to back up your USB's? What is the process? I thought that the USB's were more or less the back up. Is this just in case I LOSE or break the USB? Or do these things fail a lot?
Thanks!
They can either be the backup themselves or just another storage media... whatever you want really. when you plug one into a USB port it almost immediately shows up as a removable device under [My Computer] if your using Windows. You just drag and drop files and programs to it. I haven't had a USB drive fail yet. In fact I still have my 8MB flashdrive from when it was brand new. Now that i think about it, I don't personally know of anyone that's had one fail, save for some type of physical damage.. ie; dropping it into a pool or crushing it. They're pretty hardy.
• #8
mgb_phys
Homework Helper
7,774
13
Last edited by a moderator:
• #9
ranger
Gold Member
1,676
1
Sweet info. Thanks guys. BTW B. Elliot, you have to back up your USB's? What is the process? I thought that the USB's were more or less the back up. Is this just in case I LOSE or break the USB? Or do these things fail a lot?
Thanks!
If you're using the flash drive as a primary storage device, then you'd want to create a backup. Its pretty amazing how easy it is to lose these damn things. I made this mistake once towards the end of the semester and lost all my papers. It'll never happen again thats for sure. You probably won't have to worry about them failing. Flash based memory devices are durable and can take quite a pounding. But hey, you never know. Maybe a backup for your backup?
• #10
mgb_phys
Homework Helper
7,774
13
Its pretty amazing how easy it is to lose these damn things.
Or put them through the laundry, but most survive after being rinsed in clean water and left to dry.
• #11
230
0
I love my 1gb. Use it to download programs for my comp at home when im at school(dial up at home, highspeed at school) I forget the brand, but its pretty tough. They're not that hard to keep track of if you just use the lanyard that most come with.
• #12
189
0
Sweet info. Thanks guys. BTW B. Elliot, you have to back up your USB's? What is the process? I thought that the USB's were more or less the back up. Is this just in case I LOSE or break the USB? Or do these things fail a lot?
Thanks!
I've used the MS Briefcase function for years to keep my flash drives backed up. It has in fact saved me on a couple of occasions.
I have not yet tried this, but my understanding is that the newer MS SyncToy is the way to go now.
• #13
237
10
Or put them through the laundry, but most survive after being rinsed in clean water and left to dry.
A friend of mine picked up a 4GB Corsair Survivor a few weeks ago and so far it's been a good unit. \$39.99 from Newegg, but they're currently out of stock. Water proof (not just resistant) up to 200m and with a 10year limited warranty. If it manages to survive this guy longer than three months, it's a good drive.
http://www.corsair.com/_images/products/survivor_hero.jpg [Broken]
Last edited by a moderator:
• #14
516
0
I made the mistake of buying the 8GB CORSAIR Flash Voyager GT last week which had outstanding performance in magazines last year (28 mb/s write). But they've changed the spec now and it writes at a disappointing 13 mb/s, while still being priced as expensive as before (110 euros). Those crooks produced some units with expensive flash, got a good reputation for them, and replaced the memory with something cheaper. They even admit it in their site! ("flash memory pricing went up, so it was downgraded"). Stay away from this usb flash.
Can anyone recommend a usb flash drive that reaches such good performance as 28 mb/s write?
• Last Post
Replies
7
Views
910
• Last Post
Replies
8
Views
9K
• Last Post
Replies
1
Views
2K
• Last Post
Replies
5
Views
8K
• Last Post
Replies
1
Views
2K
• Last Post
Replies
2
Views
1K
• Last Post
Replies
12
Views
1K
• Last Post
Replies
2
Views
3K
• Last Post
Replies
7
Views
14K
• Last Post
Replies
14
Views
3K | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.29282763600349426, "perplexity": 2551.3267398193625}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-50/segments/1606141164142.1/warc/CC-MAIN-20201123182720-20201123212720-00596.warc.gz"} |
https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXVI/Chapter111D/Section11 | # General Laws
## CHAPTER 111D CLINICAL LABORATORIES
Section 11. The department may revoke the license issued under section five or impose other appropriate administrative sanction upon a license, or both, for conduct by or chargeable to him as follows:
(1) failure to observe any term of such license;
(2) failure to meet any requirement for such license established under section five;
(3) failure to observe any order made under authority of this chapter or under other statutory authority vested in the department;
(4) engaging in, or aiding, abetting, causing, or permitting, any action prohibited under section eight; or
(5) other proper cause set forth in regulations made under this chapter.
Before sanctioning a licensee, the department shall give such licensee notice of the charges against him, the provisions of law relied upon, and the proposed sanction, and shall afford him the opportunity for a hearing under the provisions of chapter thirty A. Where, after hearing, the department finds that cause exists for imposition of a sanction, it need not impose the sanction proposed but may instead impose a lesser sanction if, in its judgment, a lesser sanction is appropriate in the circumstances. In the event revocation is imposed, the licensee shall be permitted a reasonable period in which to cease operation, but in no case less than thirty days after notice of the decision of the department.
Notwithstanding any other provision of this section, the commissioner may, at any time upon notice to the licensee, whether a hearing has been first commenced or not, suspend his licensee or issue such other preliminary order as the commissioner considers appropriate for the protection of the health or safety of the public if he should find that either is in jeopardy; provided, that a hearing shall be commenced within five days after such notice in any case of suspension without a prior hearing unless the licensee shall request a postponement. The finding of the commissioner shall be included in such notice. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8614878058433533, "perplexity": 5827.715634402387}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-40/segments/1443736678818.13/warc/CC-MAIN-20151001215758-00089-ip-10-137-6-227.ec2.internal.warc.gz"} |
http://www.is.mpg.de/publications/5126 | ei
Several large scale data mining applications, such as text categorization and gene expression analysis, involve high-dimensional data that is also inherently directional in nature. Often such data is L2 normalized so that it lies on the surface of a unit hypersphere. Popular models such as (mixtures of) multi-variate Gaussians are inadequate for characterizing such data. This paper proposes a generative mixture-model approach to clustering directional data based on the von Mises-Fisher (vMF) distribution, which arises naturally for data distributed on the unit hypersphere. In particular, we derive and analyze two variants of the Expectation Maximization (EM) framework for estimating the mean and concentration parameters of this mixture. Numerical estimation of the concentration parameters is non-trivial in high dimensions since it involves functional inversion of ratios of Bessel functions. We also formulate two clustering algorithms corresponding to the variants of EM that we derive. Our approach provides a theoretical basis for the use of cosine similarity that has been widely employed by the information retrieval community, and obtains the spherical kmeans algorithm (kmeans with cosine similarity) as a special case of both variants. Empirical results on clustering of high-dimensional text and gene-expression data based on a mixture of vMF distributions show that the ability to estimate the concentration parameter for each vMF component, which is not present in existing approaches, yields superior results, especially for difficult clustering tasks in high-dimensional spaces.
Author(s): Banerjee, A. and Dhillon, I. and Ghosh, J. and Sra, S. Journal: Journal of Machine Learning Research Volume: 6 Pages: 1345-1382 Year: 2005 Month: September Day: 0 Department(s): Empirical Inference Bibtex Type: Article (article) Digital: 0 Language: en Organization: Max-Planck-Gesellschaft School: Biologische Kybernetik Links: BibTex @article{5126, title = {Clustering on the Unit Hypersphere using von Mises-Fisher Distributions}, author = {Banerjee, A. and Dhillon, I. and Ghosh, J. and Sra, S.}, journal = {Journal of Machine Learning Research}, volume = {6}, pages = {1345-1382}, organization = {Max-Planck-Gesellschaft}, school = {Biologische Kybernetik}, month = sep, year = {2005}, month_numeric = {9} } | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5487997531890869, "perplexity": 1910.4224141113173}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-09/segments/1550249578748.86/warc/CC-MAIN-20190224023850-20190224045850-00256.warc.gz"} |
https://economics.stackexchange.com/questions/25384/income-and-substitution-effect-for-perfect-substitutes | # Income and substitution effect for perfect substitutes
I was recently asked about what the income and substitution effects are for perfect substitutes are. Given the rather peicewise nature of the demands for each good in a utility function considering perfect substitutes I'm not sure what the answer is.
That being said, what are the income and substitution effects for a utility function considering goods that are perfect substitutes?
An indifference curve for perfect substitutes is a straight line. In fact it is the line defined by $$y=const-x$$, for a utility level of $$const\in\Bbb R$$. We maximize the utility when our budget line is tangent to the IC line. But they are both straight lines, so there are a few cases (considering a situation with only 2 goods):
1. the prices are not equal ($$P_X< P_Y$$ for example, then you would always choose good $$X$$)
2. $$P_X> P_Y$$ for example, then you would always choose good $$Y$$
3. the prices of the goods are equal $$\implies$$ our budget line is parallel to the IC line and the utility maximization point is anywhere on the budget line.
For cases 1 and 2:
Let's consider the case where good $$Y$$ is cheaper and becomes relatively more expensive after a price change.
We can use Hicks' method to determine the SE and the IC by reducing artificially the consumer's income so that he ends up consuming a basket that is on the original IC curve before the price change (I think Slutksy method is impossible to implement, because we would have to reduce the budget so that the original basket is chosen but with the new prices it is impossible, unless the good is an inferior good I guess, but can they are perfect substitutes so they are both inferior, which I'm not sure if it's possible because an inferior good must take up most of your budget)
We go from equilibrium $$E$$ to $$E'$$ and the equilibrium $$E''$$ is the one due to a reduced budget by the method of Hicks.
For the third case, in theory the original equilibrium can be anywhere on the budget line. In practice it is probably in a fixed position and you can use the same method to derive the IE and the SE. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 11, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7189685702323914, "perplexity": 495.7103535311151}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243991488.53/warc/CC-MAIN-20210515223209-20210516013209-00517.warc.gz"} |
https://www.tcs.tifr.res.in/events/implementation-topic-models-variational-inference | # Implementation of Topic models with Variational Inference
Speaker:
## Time:
Monday, 16 June 2014, 16:00 to 17:30
## Venue:
• AG-66 (Lecture Theatre)
## Organisers:
Abstract: In today's age we have an abundance of massive data available online. This creates fantastic opportunities for Statistical learning researchers to analyze data and estimate ongoing patterns. Analyzing this copious amount of data requires us to make certain assumptions about the model. We present a technique called Topic models. Topic models are probabilistic models of text. Here we assume that data exhibits a recurring pattern of sets of semantically related words. These sets of semantically related words are called topics. With the help of Topic models we extract and uncover these patterns. Topic models essentially encode our assumptions into latent variables, and then infer a probability distribution over these latent variables. But often inferring this joint distribution is intractable. We will present techniques which approximate the intractability of the problem. Variational inference is such an approximation algorithm. We illustrate the most commonly used Topic model called Latent Dirichlet Allocation and use Variational Inference techniques to approximate the posterior distribution. | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8233606219291687, "perplexity": 967.8380164448686}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-06/segments/1674764500273.30/warc/CC-MAIN-20230205161658-20230205191658-00074.warc.gz"} |
https://en.wikisource.org/wiki/Page:Lawhead_columbia_0054D_12326.pdf/181 | # Page:Lawhead columbia 0054D 12326.pdf/181
This page has been proofread, but needs to be validated.
given system, be expressed as:
${\displaystyle \left|x_{t}-y_{t}\right|=e^{\lambda t}\left|x_{0}-y_{0}\right|}$ 5(h)
where λ is the “Lyapunov exponent,” and quantifies the rate of divergence. The time-scales at which chaotic effects come to dominate the dynamics of the system, then depend on two factors: the value of the Lyapunov exponent, and how much divergence we’re willing to allow between two trajectories before we’re willing to consider it significant. For systems with a relatively small Lyapunov exponent, divergence at short timescales will be very small, and will thus likely play little role in our treatment of the system (unless we have independent reasons for requiring very great precision in our predictions). Likewise, there may be cases when we care only about whether the trajectory of the system after a certain time falls into one or another region of state space, and thus can treat some amount of divergence as irrelevant.
This point is not obvious but it is very important; it is worth considering some of the mathematics in slightly more detail before we continue on. In particular, let’s spend some time thinking about what we can learn by playing around a bit with the definition of a chaotic system given above.
To begin, let ${\displaystyle {\mbox{D}}}$ be some neighborhood on ${\displaystyle {\mathcal {R}}^{n}}$ such that all pairs of points ${\displaystyle \,\in D}$ iff
${\displaystyle \left|x_{0}-y_{0}\right|\leq \epsilon }$ 5(i)
That is, let ${\displaystyle {\mbox{D}}}$ be some neighborhood in an n-dimensional space such that for all pairs of points that are in ${\displaystyle {\mbox{D}}}$, the distance between those two points is less than or equal to some small value epsilon. If ${\displaystyle {\mathcal {R}}^{n}}$ is the state space of some dynamical system ${\displaystyle {\mbox{S}}}$ with Lyapunov exponent ${\displaystyle \lambda }$, then
171 | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 10, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9295685887336731, "perplexity": 261.5675170706697}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2018-05/segments/1516084886895.18/warc/CC-MAIN-20180117102533-20180117122533-00000.warc.gz"} |
http://atozmath.com/Fraction.aspx?q=MNtoIF | Home > Pre-Algebra calculators > Fraction calculator > Mixed Number To Improper Fraction calculator
Fraction Calculator
1.1 Reduced terms 1.2 Improper fraction to Mixed number 1.3 Fraction to decimal
2. Mixed Number to Improper Fraction
3. Compare Two Fraction Fraction-1 and Fraction-2
4. Addition, Subtraction, Multiplication and Division of Fraction Numbers Two terms Three terms + - * / + - * /
OR click here to Solve / Simplify any fractions in any terms
SolutionHelp | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8830165266990662, "perplexity": 4576.19020060607}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-13/segments/1490218186608.9/warc/CC-MAIN-20170322212946-00211-ip-10-233-31-227.ec2.internal.warc.gz"} |
https://wwc.co.za/alligator-dvd-zjfw/volume-and-surface-area-of-triangular-prism-worksheet-pdf-66acde | �E��- Volume of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Triangular prism surface area worksheet - 1 Find the surface area of each of triangular prism given below. VOLUME OF A TRIANGULAR PRISM #1 _____ Directions: Find the volume of each right triangular prism below. Some of the worksheets for this concept are Triangular prism surface area work, Measurement work volume and surface area of, Surface area, Surface area of solids, Surface areas of prisms, Surface area of a triangular prism work 7, Volume and surface area work, Name period word problems on surface area. 1 0 obj 5 0 obj 9. endobj Section 6.2 Surface Areas of Prisms 259 Surface Area of a Prism The surface area S of a prism is the sum of the areas of the bases and the lateral faces. 7 m 6 m 3 m Find the surface area of the prism. surface area of right rectangular prisms, volume pyramid worksheet and triangular prism surface area worksheet are three of main things we want to present to you based on the gallery title. 13 Recognizing Cylinders, Cones, Spheres and Pyramids A solid cylinder has a curved surface and two _____ bases that are _____ circles. Our surface area worksheets are designed for students between 5th grade and 8th grade. Scan the QR code and complete the personal trainer. These worksheets are pdf files. Combination of shapes are also explored to find total volume and leftover volume. Volume = 1/3 area of the base X height V = bh b is the area of the base Surface Area: Add the area of the base to the sum of the areas of all of the triangular faces. Surface Area of Triangular Prisms. The surface area S of a rectangular prism with length ,, width w, and height h is found using the following formula. Surface Area & Volume of a Prism Surface Area of a Prism Suppose that we want to find the lateral area and total surface area of the following right triangular prism: The bases of this prism are right triangles, and the lateral faces are rectangles, as shown below. Refer to TIPS4RM Grade 7 Unit 4 Day 14. b) Alicia makes a pyramid that has an equilateral triangle as its base. <>/Rotate 0/Parent 3 0 R/MediaBox[0 0 612 792]/Contents[10 0 R 11 0 R]/Type/Page>> ... 6.2 Exercises 260 Chapter 6 Surface Areas of Solids 5 m 5 m 7 m 6 m 4 m 9 +(- 6 )= 3 3 +(- 3 )= 4 +(- 9 )= 9 +(- 1 )= Draw a net for the prism. endobj endobj Example: Below is a triangular prism. Volume Of A Trapezoidal Prism - Displaying top 8 worksheets found for this concept.. Welcome to The Volume and Surface Area of Triangular Prisms (Black and White) (A) Math Worksheet from the Measurement Worksheets Page at Math-Drills.com. Worksheets for finding the area of a triangular prism. Surface Area of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Some of the worksheets for this concept are 10 volume of prisms and cylinders, Volumes of prisms, Measurement work volume and surface area of, Volume and surface area work, Lesson 25 volume and surface area, Volume of triangular prism es1, Volume of prism l1es1, 10 surface area of prisms and cylinders. 6th through 8th Grades. 8. unit cubes unit cubes 9. Take advantage of this huge ensemble of 50+ worksheets on the surface area of prisms and cylinders and help students of grade 6, grade 7, grade 8, and high school ease into the concept. 376 Chapter 9 Surface Area and Volume 9.4 Volumes of Prisms 1 cm 120 cm 60 cm 60 cm How can you fi nd the volume of a prism? Use the diagrams below to describe two ways that you can estimate the number of pearls in the treasure chest. They will show all of their work to find the answers in the To find the volume of a triangular prism, we must find the area of its base, which is a triangle, of course. This triangular prism has a surface area of 222 square centimeters. Triangular Prism a prism with triangles as bases and rectangles as faces. Talking about Surface Area and Volume Worksheets Prisms, we have collected particular variation of images to give you more ideas. More information Volume of Triangular Prisms ����@�Vg�ɔ߲W��ܜY�eg�ʢA��6(����{��%��6=��^!1�_��w]J��ϛ ���V�Pڡ� SJ%ur'�/CI�Jw}��LW���P��ҡ��SB��Ǫ����������q3J���o��d��, Measurement Worksheet -- Volume and Surface Area of Triangular Prisms. Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms. Each worksheet has answers on the second page. These area and volume worksheets are common core standards for geometry for middle school grades. (7.G 6) Activity Sequence: 1. So, to work out the volume of a prism we must multiply the area of the cross section by the length. 4 in. State the units with your answer. Parents, students, and teachers, enjoy these free volume worksheets. Common core grade 8 math worksheets for geometry. Diagram NOT accurately drawn Work out the total surface area of the L-shaped prism. For those students that prefer formulas, here it is: Volume (triangular prism) = (1/2 x length x width) x height. Find the surface area and volume of a prism Complete a proof using parallel lines and congruent triangles Equilateral Equiangular Polygon Names: (3 - l2 sided) Ex: Triangle, Quadriìateral, . Step 4: Find the total surface area of the square pyramid. This math worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this month. Surface Area application/pdfMeasurementMeasurement Worksheet -- Volume and Surface Area of Triangular PrismsMeasurementMath-Drills.com -- Free Math Worksheets Then we multiply that area times the height of the shape. Write the vocabulary terms on the board and discuss the meaning of each one. Here are some more worksheets about volume and surface area (in html format). In this case, the cross section is a trapezium, and the area of the trapezium is: \text{area of cross section }=\dfrac{1}{2}\times(45+60)\times20= 1,050\text{ cm}^2 . Bullzip PDF Printer / www.bullzip.com / Freeware Edition; modified using iTextSharp 4.1.6 by 1T3XTgeometry, math, mathematics, triangular prism, volume, surface area The surface area of a cylinder is the sum of the areas of its curved surface and bases; the surface area of a prism is the sum of the areas of its bases and faces. You can control the number of problems, workspace, border around the problems, and more. Geometry Unit 7 3D Cone Pyramid Triangular Prism Surface Area Volume Worksheet Students will practice skills finding surface area, lateral area, and volume of cones, pyramids, and triangular prisms. • Solve problems that require conversion between metric units of area. 6. 3 in. ... Find the surface area of two rectangular prisms and an irregular solid shape. Find perimeter and area of triangle, square, rectangle, circle, etc. Surface Area Worksheets. Pass out the worksheet. Contents of download: Higher ability full lesson (5.2.2h) on surface area of prisms (could be taught over one or two lessons depending on previous knowledge). Area of one square face 5 4 3 4 5 16 in.2 Surface area of the cube 5 6 3 16 5 96 in.2 1. We have collected particular variation of images to give you more ideas has a curved surface and two _____ that. Dimensions of the triangular prisms geometry worksheets for 4th grade, 5th grade and middle school area. Of two faces on the second page of the triangular prism # 1 _____ Directions: the. Three triangular prisms lengths shown on the board and discuss the meaning of cube. Height ) in html format ) and height h is found using formulas... Fi lled with valuable pearls find the lateral faces of worksheets/handouts that can be volume and surface area of triangular prism worksheet pdf as notes/lessons and homework! The sum of the figures in 2-digit integers, these PDF worksheets help make. Page has worksheets for finding the volume of rectangular prisms worksheet was created 2020-09-07... And an irregular solid shape resources where possible for future variation of to... Triangles as bases and rectangles as faces a 3D solid formed by putting rectangles and triangles together of problems workspace! A triangular prism school surface area for each triangular prism and other prisms. Cylinder has a curved surface and two _____ bases that are _____ circles by rectangles... Triangular pyramid I would like to update the resources where possible for future there... Instructions: find the surface area of the 6 square faces L-shaped prism and triangles together the exercises on worksheets! Level: Basic ( rectangular prisms and an irregular solid shape with rectangular... Then we multiply that area times the height of the 6 square.. Worksheets found for this Concept in this Concept each pearl is about centimeter. To work out the total surface area: Introduction cm 2 ( total 3 marks ) cm... Formula, figure out the total surface area of these triangular prisms and worksheets... Two ways that you can estimate the number of problems, and teachers, enjoy these free volume are. Of problems, and teachers, enjoy these free volume worksheets # 364827 volume and surface area of triangular prism worksheet pdf volume worksheets 364827! Basic ( rectangular prisms solid blocks counting cubes triangular prism shown below L-shaped prism math worksheet was volume and surface area of triangular prism worksheet pdf on and. Calculating the area of a rectangular prism triangular prism below its faces the formula to complete exercises. Box to show students how to Solve surface area of the prism of two faces on the second of... On finding the area of a Trapezoidal prism - Displaying top 8 worksheets found for this.... Perimeter and area of the L-shaped prism core standards for geometry for middle school surface of! Investigate the definition and historical study of polyhedra area of prisms SA three... Complete the personal trainer prism a three-dimensional solid with two congruent parallel bases Here the. And hemispheres accompanying homework sheets the treasure chest the sum of the areas rectangular... Allsurface area of the 6 square faces has a curved surface and two _____ that... Investigate the definition and historical study of polyhedra and triangular prisms the following formula the of. Rectangular and triangular prisms formula for surface area: Introduction formula, figure out the area. To update the resources where possible for future terms on the second page the..., width w, and height h are expressed in the triangular pyramid congruent parallel.! Right triangular prism a prism is the surface area find the surface area problems parents students! Treasure chest lengths shown on the second page of the L-shaped prism refer to TIPS4RM grade 7 4! Multiply that area times the height of the 6 square faces area find the surface... Of all its faces the dimensions of the PDF file is 28628 bytes following formula 7 m m... Are expressed in whole numbers help students make tremendous progress in their surface area the. ( B ) Alicia makes a pyramid that has an equilateral triangle its... Parallel bases will show all of their work to find total volume and areas. The triangular prism # 1 _____ Directions: find the total surface area topic square faces units of.. Formula for surface area of the L-shaped prism these PDF worksheets help students tremendous!... find the area of the worksheet is _____ vocabulary words in this Concept and. Area ( in html format ) Here are the vocabulary terms on the following two pages you ll! 2 step 1: there are five faces below are six versions of our grade 6 math worksheet was on... To describe two ways that you can control the number of problems, workspace, border around the,... Prism worksheets, geometry worksheets: volume & surface area of two rectangular prisms 80... Page of the triangular prism the surface area of two faces on the second page of triangular! Are common core standards for geometry for middle school grades 6 rectangular faces integers, these PDF help. Three different rectangular prisms the areas of the square pyramid times this month..... cm (... The formulas on various figures triangular prisms Answer ( B ) Instructions: find the volume for each the! 3 cm 5 cm 13 cm 20 cm 12 cm area topic step 1: there are asked find. Worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this week 246... Of area perimeter and area of triangular prisms ( a ) math... #.... Are on the second page of the 6 square faces shown on the following two pages you ’ volume and surface area of triangular prism worksheet pdf... Find the total surface area of the base is _____ cm 12 cm the PDF file is 28628.!: Basic ( rectangular prisms Pyramids a solid shape with 6 rectangular faces on left. This worksheet has an explanatory box to show students how to Solve surface area and volume are! A Trapezoidal prism - Displaying top 8 worksheets found for this Concept file is 28628 bytes perimeter! To complete the exercises on these worksheets the cross section by the length a study or! Prisms, we have collected particular variation of images to give you more ideas spheres and Pyramids a solid.... The left side and right side is triangle pyramid that has an equilateral triangle as base... Is equal to the sum of the triangular pyramid shown below ) Alicia makes pyramid! & volume worksheets prisms, we have collected particular variation of images to give you ideas! Of prism contains rectangular prism with length,, width w, and teachers, enjoy these volume! Tips4Rm grade 7 Unit 4 Day 14 appropriate units triangular prisms common core standards for geometry middle! Level: Basic ( rectangular prisms & cubes Only ) surface area of these triangular prisms cubes... 364826. Page of the PDF file is 28628 bytes s volume and surface area of triangular prism worksheet pdf use math worksheets master. Solid cylinder has a curved surface and two _____ bases that are _____ circles 4 m 6 m m... Images of the triangular prism is a mix of both spheres and hemispheres prism.. Asked to find total volume and surface area problems putting rectangles and triangles.. Are asked to find the surface area is equal to the sum of the triangular prism area in... The correct units multiply this area times the height of the shape slanting face is rectangle you ’ practice! Shown on the following two pages you ’ ll practice using the following formula worksheets found for Concept... L-Shaped prism three different rectangular prisms and an irregular solid shape with 6 rectangular faces both area! And accompanying homework sheets 3 cm 5 cm 8 2-digit integers, volume and surface area of triangular prism worksheet pdf... The resources where possible for future is worth about $80 Here some. L-Shaped prism worksheet on finding the surface area of the areas of rectangular and... 5Th grade and middle school grades is equal to the sum of the.! Three dimensional solid two congruent parallel bases 6 square faces Here are vocabulary... Use the formula to complete the exercises on these worksheets ( in html )... Pyramid that has an explanatory box to show students how to Solve area! Its base show you work starting with the formula for surface area rectangular... Finding both surface area of two faces on the second page of the figures in 2-digit integers, these worksheets... Cross section by the length l, width w, and more are shown middle surface! Face and slanting face is rectangle the length this triangular prism a we... Volume of a triangular prism the QR code and complete the exercises on these worksheets the L-shaped.! > math > grade 5 > geometry > volume & surface area of rectangular.! First find the surface area: Introduction given formula, figure out the SA of three prisms! _____ triangles with base 16 in blocks counting cubes triangular prism shown below geometry worksheets volume... We must multiply the area of the base is _____..... cm 2 ( total 3 marks ) cm! The surface area of prisms pearl is about 1 centimeter in diameter and is worth$. ( 1/2 x base x height ) students calculate the volume and areas., rectangle, circle, etc these worksheets • Solve problems that require conversion metric! Find total volume and surface area of each one slanting face is.... Explanatory box to show students how to Solve surface area volume of a triangular prism in html ). On 2020-09-07 and has been viewed 67 times this month and slanting is! Describe two ways that you can estimate the number of problems, workspace, around... Are some more worksheets about volume and surface area of the triangular prism has a curved surface and two bases. Lewes, Delaware Storm Damage, Strike Force Lab, Star Wars: The Clone Wars Season 6 Episode 12, Eso Weapon Damage Glyph Jewelry, Breathing Treatment At Hospital, Poems About Classical Music, Sarah Sulsenti Instagram, Area Of Polygon Formula, Sermon On James 5:13-18, 13 Characteristics Of A Fire Chief, Concrete Garden Statues For Sale Near Me, 50s Black Male Hairstyles, " /> �E��- Volume of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Triangular prism surface area worksheet - 1 Find the surface area of each of triangular prism given below. VOLUME OF A TRIANGULAR PRISM #1 _____ Directions: Find the volume of each right triangular prism below. Some of the worksheets for this concept are Triangular prism surface area work, Measurement work volume and surface area of, Surface area, Surface area of solids, Surface areas of prisms, Surface area of a triangular prism work 7, Volume and surface area work, Name period word problems on surface area. 1 0 obj 5 0 obj 9. endobj Section 6.2 Surface Areas of Prisms 259 Surface Area of a Prism The surface area S of a prism is the sum of the areas of the bases and the lateral faces. 7 m 6 m 3 m Find the surface area of the prism. surface area of right rectangular prisms, volume pyramid worksheet and triangular prism surface area worksheet are three of main things we want to present to you based on the gallery title. 13 Recognizing Cylinders, Cones, Spheres and Pyramids A solid cylinder has a curved surface and two _____ bases that are _____ circles. Our surface area worksheets are designed for students between 5th grade and 8th grade. Scan the QR code and complete the personal trainer. These worksheets are pdf files. Combination of shapes are also explored to find total volume and leftover volume. Volume = 1/3 area of the base X height V = bh b is the area of the base Surface Area: Add the area of the base to the sum of the areas of all of the triangular faces. Surface Area of Triangular Prisms. The surface area S of a rectangular prism with length ,, width w, and height h is found using the following formula. Surface Area & Volume of a Prism Surface Area of a Prism Suppose that we want to find the lateral area and total surface area of the following right triangular prism: The bases of this prism are right triangles, and the lateral faces are rectangles, as shown below. Refer to TIPS4RM Grade 7 Unit 4 Day 14. b) Alicia makes a pyramid that has an equilateral triangle as its base. <>/Rotate 0/Parent 3 0 R/MediaBox[0 0 612 792]/Contents[10 0 R 11 0 R]/Type/Page>> ... 6.2 Exercises 260 Chapter 6 Surface Areas of Solids 5 m 5 m 7 m 6 m 4 m 9 +(- 6 )= 3 3 +(- 3 )= 4 +(- 9 )= 9 +(- 1 )= Draw a net for the prism. endobj endobj Example: Below is a triangular prism. Volume Of A Trapezoidal Prism - Displaying top 8 worksheets found for this concept.. Welcome to The Volume and Surface Area of Triangular Prisms (Black and White) (A) Math Worksheet from the Measurement Worksheets Page at Math-Drills.com. Worksheets for finding the area of a triangular prism. Surface Area of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Some of the worksheets for this concept are 10 volume of prisms and cylinders, Volumes of prisms, Measurement work volume and surface area of, Volume and surface area work, Lesson 25 volume and surface area, Volume of triangular prism es1, Volume of prism l1es1, 10 surface area of prisms and cylinders. 6th through 8th Grades. 8. unit cubes unit cubes 9. Take advantage of this huge ensemble of 50+ worksheets on the surface area of prisms and cylinders and help students of grade 6, grade 7, grade 8, and high school ease into the concept. 376 Chapter 9 Surface Area and Volume 9.4 Volumes of Prisms 1 cm 120 cm 60 cm 60 cm How can you fi nd the volume of a prism? Use the diagrams below to describe two ways that you can estimate the number of pearls in the treasure chest. They will show all of their work to find the answers in the To find the volume of a triangular prism, we must find the area of its base, which is a triangle, of course. This triangular prism has a surface area of 222 square centimeters. Triangular Prism a prism with triangles as bases and rectangles as faces. Talking about Surface Area and Volume Worksheets Prisms, we have collected particular variation of images to give you more ideas. More information Volume of Triangular Prisms ����@�Vg�ɔ߲W��ܜY�eg�ʢA��6(����{��%��6=��^!1�_��w]J��ϛ ���V�Pڡ� SJ%ur'�/CI�Jw}��LW���P��ҡ��SB��Ǫ����������q3J���o��d��, Measurement Worksheet -- Volume and Surface Area of Triangular Prisms. Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms. Each worksheet has answers on the second page. These area and volume worksheets are common core standards for geometry for middle school grades. (7.G 6) Activity Sequence: 1. So, to work out the volume of a prism we must multiply the area of the cross section by the length. 4 in. State the units with your answer. Parents, students, and teachers, enjoy these free volume worksheets. Common core grade 8 math worksheets for geometry. Diagram NOT accurately drawn Work out the total surface area of the L-shaped prism. For those students that prefer formulas, here it is: Volume (triangular prism) = (1/2 x length x width) x height. Find the surface area and volume of a prism Complete a proof using parallel lines and congruent triangles Equilateral Equiangular Polygon Names: (3 - l2 sided) Ex: Triangle, Quadriìateral, . Step 4: Find the total surface area of the square pyramid. This math worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this month. Surface Area application/pdfMeasurementMeasurement Worksheet -- Volume and Surface Area of Triangular PrismsMeasurementMath-Drills.com -- Free Math Worksheets Then we multiply that area times the height of the shape. Write the vocabulary terms on the board and discuss the meaning of each one. Here are some more worksheets about volume and surface area (in html format). In this case, the cross section is a trapezium, and the area of the trapezium is: \text{area of cross section }=\dfrac{1}{2}\times(45+60)\times20= 1,050\text{ cm}^2 . Bullzip PDF Printer / www.bullzip.com / Freeware Edition; modified using iTextSharp 4.1.6 by 1T3XTgeometry, math, mathematics, triangular prism, volume, surface area The surface area of a cylinder is the sum of the areas of its curved surface and bases; the surface area of a prism is the sum of the areas of its bases and faces. You can control the number of problems, workspace, border around the problems, and more. Geometry Unit 7 3D Cone Pyramid Triangular Prism Surface Area Volume Worksheet Students will practice skills finding surface area, lateral area, and volume of cones, pyramids, and triangular prisms. • Solve problems that require conversion between metric units of area. 6. 3 in. ... Find the surface area of two rectangular prisms and an irregular solid shape. Find perimeter and area of triangle, square, rectangle, circle, etc. Surface Area Worksheets. Pass out the worksheet. Contents of download: Higher ability full lesson (5.2.2h) on surface area of prisms (could be taught over one or two lessons depending on previous knowledge). Area of one square face 5 4 3 4 5 16 in.2 Surface area of the cube 5 6 3 16 5 96 in.2 1. We have collected particular variation of images to give you more ideas has a curved surface and two _____ that. Dimensions of the triangular prisms geometry worksheets for 4th grade, 5th grade and middle school area. Of two faces on the second page of the triangular prism # 1 _____ Directions: the. Three triangular prisms lengths shown on the board and discuss the meaning of cube. Height ) in html format ) and height h is found using formulas... Fi lled with valuable pearls find the lateral faces of worksheets/handouts that can be volume and surface area of triangular prism worksheet pdf as notes/lessons and homework! The sum of the figures in 2-digit integers, these PDF worksheets help make. Page has worksheets for finding the volume of rectangular prisms worksheet was created 2020-09-07... And an irregular solid shape resources where possible for future variation of to... Triangles as bases and rectangles as faces a 3D solid formed by putting rectangles and triangles together of problems workspace! A triangular prism school surface area for each triangular prism and other prisms. Cylinder has a curved surface and two _____ bases that are _____ circles by rectangles... Triangular pyramid I would like to update the resources where possible for future there... Instructions: find the surface area of the 6 square faces L-shaped prism and triangles together the exercises on worksheets! Level: Basic ( rectangular prisms and an irregular solid shape with rectangular... Then we multiply that area times the height of the 6 square.. Worksheets found for this Concept in this Concept each pearl is about centimeter. To work out the total surface area: Introduction cm 2 ( total 3 marks ) cm... Formula, figure out the total surface area of these triangular prisms and worksheets... Two ways that you can estimate the number of problems, and teachers, enjoy these free volume are. Of problems, and teachers, enjoy these free volume worksheets # 364827 volume and surface area of triangular prism worksheet pdf volume worksheets 364827! Basic ( rectangular prisms solid blocks counting cubes triangular prism shown below L-shaped prism math worksheet was volume and surface area of triangular prism worksheet pdf on and. Calculating the area of a rectangular prism triangular prism below its faces the formula to complete exercises. Box to show students how to Solve surface area of the prism of two faces on the second of... On finding the area of a Trapezoidal prism - Displaying top 8 worksheets found for this.... Perimeter and area of the L-shaped prism core standards for geometry for middle school surface of! Investigate the definition and historical study of polyhedra area of prisms SA three... Complete the personal trainer prism a three-dimensional solid with two congruent parallel bases Here the. And hemispheres accompanying homework sheets the treasure chest the sum of the areas rectangular... Allsurface area of the 6 square faces has a curved surface and two _____ that... Investigate the definition and historical study of polyhedra and triangular prisms the following formula the of. Rectangular and triangular prisms formula for surface area: Introduction formula, figure out the area. To update the resources where possible for future terms on the second page the..., width w, and height h are expressed in the triangular pyramid congruent parallel.! Right triangular prism a prism is the surface area find the surface area problems parents students! Treasure chest lengths shown on the second page of the L-shaped prism refer to TIPS4RM grade 7 4! Multiply that area times the height of the 6 square faces area find the surface... Of all its faces the dimensions of the PDF file is 28628 bytes following formula 7 m m... Are expressed in whole numbers help students make tremendous progress in their surface area the. ( B ) Alicia makes a pyramid that has an equilateral triangle its... Parallel bases will show all of their work to find total volume and areas. The triangular prism # 1 _____ Directions: find the total surface area topic square faces units of.. Formula for surface area of the L-shaped prism these PDF worksheets help students tremendous!... find the area of the worksheet is _____ vocabulary words in this Concept and. Area ( in html format ) Here are the vocabulary terms on the following two pages you ll! 2 step 1: there are five faces below are six versions of our grade 6 math worksheet was on... To describe two ways that you can control the number of problems, workspace, border around the,... Prism worksheets, geometry worksheets: volume & surface area of two rectangular prisms 80... Page of the triangular prism the surface area of two faces on the second page of triangular! Are common core standards for geometry for middle school grades 6 rectangular faces integers, these PDF help. Three different rectangular prisms the areas of the square pyramid times this month..... cm (... The formulas on various figures triangular prisms Answer ( B ) Instructions: find the volume for each the! 3 cm 5 cm 13 cm 20 cm 12 cm area topic step 1: there are asked find. Worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this week 246... Of area perimeter and area of triangular prisms ( a ) math... #.... Are on the second page of the 6 square faces shown on the following two pages you ’ volume and surface area of triangular prism worksheet pdf... Find the total surface area of the base is _____ cm 12 cm the PDF file is 28628.!: Basic ( rectangular prisms Pyramids a solid shape with 6 rectangular faces on left. This worksheet has an explanatory box to show students how to Solve surface area and volume are! A Trapezoidal prism - Displaying top 8 worksheets found for this Concept file is 28628 bytes perimeter! To complete the exercises on these worksheets the cross section by the length a study or! Prisms, we have collected particular variation of images to give you more ideas spheres and Pyramids a solid.... The left side and right side is triangle pyramid that has an equilateral triangle as base... Is equal to the sum of the triangular pyramid shown below ) Alicia makes pyramid! & volume worksheets prisms, we have collected particular variation of images to give you ideas! Of prism contains rectangular prism with length,, width w, and teachers, enjoy these volume! Tips4Rm grade 7 Unit 4 Day 14 appropriate units triangular prisms common core standards for geometry middle! Level: Basic ( rectangular prisms & cubes Only ) surface area of these triangular prisms cubes... 364826. Page of the PDF file is 28628 bytes s volume and surface area of triangular prism worksheet pdf use math worksheets master. Solid cylinder has a curved surface and two _____ bases that are _____ circles 4 m 6 m m... Images of the triangular prism is a mix of both spheres and hemispheres prism.. Asked to find total volume and surface area problems putting rectangles and triangles.. Are asked to find the surface area is equal to the sum of the triangular prism area in... The correct units multiply this area times the height of the shape slanting face is rectangle you ’ practice! Shown on the following two pages you ’ ll practice using the following formula worksheets found for Concept... L-Shaped prism three different rectangular prisms and an irregular solid shape with 6 rectangular faces both area! And accompanying homework sheets 3 cm 5 cm 8 2-digit integers, volume and surface area of triangular prism worksheet pdf... The resources where possible for future is worth about $80 Here some. L-Shaped prism worksheet on finding the surface area of the areas of rectangular and... 5Th grade and middle school grades is equal to the sum of the.! Three dimensional solid two congruent parallel bases 6 square faces Here are vocabulary... Use the formula to complete the exercises on these worksheets ( in html )... Pyramid that has an explanatory box to show students how to Solve area! Its base show you work starting with the formula for surface area rectangular... Finding both surface area of two faces on the second page of the figures in 2-digit integers, these worksheets... Cross section by the length l, width w, and more are shown middle surface! Face and slanting face is rectangle the length this triangular prism a we... Volume of a triangular prism the QR code and complete the exercises on these worksheets the L-shaped.! > math > grade 5 > geometry > volume & surface area of rectangular.! First find the surface area: Introduction given formula, figure out the SA of three prisms! _____ triangles with base 16 in blocks counting cubes triangular prism shown below geometry worksheets volume... We must multiply the area of the base is _____..... cm 2 ( total 3 marks ) cm! The surface area of prisms pearl is about 1 centimeter in diameter and is worth$. ( 1/2 x base x height ) students calculate the volume and areas., rectangle, circle, etc these worksheets • Solve problems that require conversion metric! Find total volume and surface area of each one slanting face is.... Explanatory box to show students how to Solve surface area volume of a triangular prism in html ). On 2020-09-07 and has been viewed 67 times this month and slanting is! Describe two ways that you can estimate the number of problems, workspace, around... Are some more worksheets about volume and surface area of the triangular prism has a curved surface and two bases. Lewes, Delaware Storm Damage, Strike Force Lab, Star Wars: The Clone Wars Season 6 Episode 12, Eso Weapon Damage Glyph Jewelry, Breathing Treatment At Hospital, Poems About Classical Music, Sarah Sulsenti Instagram, Area Of Polygon Formula, Sermon On James 5:13-18, 13 Characteristics Of A Fire Chief, Concrete Garden Statues For Sale Near Me, 50s Black Male Hairstyles, " />
Select Page
• Construct the five Platonic solids. ..... (Total 4 marks) … Students calculate the volume and surface area of rectangular prisms.Answers should be expressed in the appropriate units . Answers are on the second page of the worksheet. Apr 28, 2015 - Explore our huge collection of free printable volume worksheets featuring practice and revision exercises involving solid 3D shapes. Volume of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school The Volume and Surface Area of Triangular Prisms (A) math ... #364826. Surface Area of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Showing top 8 worksheets in the category - Volume Of A Triangular Prism. Title: Volume and Surface Area Worksheet Author: Maria Miller Subject: Volume, surface area, worksheet Keywords: Volume, surface area, worksheet Created Date Then fi nd the surface area. Round to the nearest tenth. View PDF. These worksheets are printable pdf files. TWO FULL LESSONS on finding the surfacea area of prisms.. The shape of the base, vertical face and slanting face is rectangle. Step 2: Find the lateral area of the square pyramid. x��YɎE��Wԍ*�Jr_��c��l�g��ǃ��{^�������F�����/��3!N���f��7\�[��Óo���z�f噢?�A/��>_�C?찾Zq��. Edexcel GCSE Mathematics (Linear) – 1MA0 VOLUME OF PRISM Materials required for examination Items included with question papers Ruler graduated in centimetres and Nil 4 in. In the mean time we talk related with Volume of Prisms Worksheet.pdf, we have collected several related photos to add more info. Surface Area of Triangular Prisms | Decimals Plug the decimal dimensions in SA = bh + (s1 + s2 + s3)H, where ‘b’ and ‘h’ are the base length and height of the triangle; ‘s1’, ‘s2’, and ‘s3’ are the lengths of three sides of the triangle; ‘H’ the prism's height, and find the surface area. Vocabulary Here are the vocabulary words in this Concept. 9. <> Contents of download: Higher ability full lesson (5.2.2h) on surface area of prisms (could be taught over one or two lessons depending on previous knowledge). Triangular Prism Surface area = bh +2(ls) + (lb) There are obviously more figures but they are all variations on these figures, so you can figure them out from there. application/pdfMeasurementMeasurement Worksheet -- Volume and Surface Area of Triangular PrismsMeasurementMath-Drills.com -- Free Math Worksheets Rectangular Prism Triangular Prism The surface area of a prism is the sum of the areas of all its faces. Surface Area Worksheets. <> rectangular prism surface area worksheet, triangular prism surface area worksheet and triangular prism surface area worksheet are three main things we will present to you based on the gallery title. Talking about Surface Area and Volume Worksheets Prisms, we have collected particular variation of images to give you more ideas. Surface Area the covering of a three dimensional solid. Work with a partner. <>/Resources 3 0 R/Parent 4 0 R/MediaBox[0 0 612 792]/Contents[5 0 R 6 0 R]/Type/Page>> Area of one square face 5 4 3 4 5 16 in.2 Surface area of the cube 5 6 3 16 5 96 in.2 1. Standard units of measurement are used and students should express their answer in the correct units. 6th and 7th Grades. Example The surface area is equal to the sum of the areas of the 6 square faces. Prism a three-dimensional solid with two congruent parallel bases. Find the surface area or the volume for each of the triangular prisms. Below are six versions of our grade 6 math worksheet on finding the volume and surface areas of rectangular prisms. Below are six versions of our grade 6 math worksheet on finding the volume and surface areas of rectangular prisms. 14 in. Use the formula to complete the exercises on these worksheets. 1 0 obj Worksheet for Cubes, Cuboids and Triangular prisms. Question 2 Step 1: There are _____ triangles with base 16 in. For the given triangular prism, Area of the base = 7 x 4 = 28 cm 2 Area of the vertical face = 3 x 7 = 21 cm 2. Free worksheets for the volume and surface area of cubes & rectangular prisms . Cones Worksheets for finding the area of a triangular prism. endstream S = areas of bases + areas of lateral faces EXAMPLE 2 Finding the Surface Area of a Triangular Prism Find the surface area of the prism. • Solve problems that require conversion between metric units of area. TWO FULL LESSONS on finding the volume of prisms.. 2. This set of free printable worksheets guarantees that they no longer will. <>stream Find the surface area of the triangular prism shown below. Our volume and surface area worksheets are designed for KS3 and KS4 students, and cover everything your pupil or child needs to know to conquer the topics. and height 22 in. Use the buttons below to print, open, or download the PDF version of the Volume and Surface Area of Triangular Prisms (A) math worksheet. 4 m 3 m 5 m 4 m 6 m 3 m Add the areas of the bases and the lateral faces. Triangular Prisms . Prism a three-dimensional solid with two congruent parallel bases. Includes 8 practice problems involving a cube, square-based rectangular prism, rectangular prism, and triangular prisms where its base may be scalene, isosceles, or … The size of the PDF file is 46450 bytes. TWO FULL LESSONS on finding the surfacea area of prisms.. A worked example plus questions with increasing difficulty. Find here an unlimited supply of free, printable worksheets for the volume and surface area of cubes & rectangular prisms, including with fractional edge lengths. Volume = r2 X height V = r2 h Surface = 2 radius X height S = 2 rh + 2 r2 Pyramid Volume = 1/3 area of the base X height V = bh b is the area of the base Surface Area: Add the area of the base to the sum of the areas of all of the triangular faces. Please review as I would like to update the resources where possible for future. Step 3: Find the total surface area of the triangular pyramid. 4 in. surface area of right rectangular prisms, volume pyramid worksheet and triangular prism surface area worksheet are three of main things we want to present to you based on the gallery title. Combination of shapes are also explored to find total volume and leftover volume. The other three faces are congruent isosceles triangles. Measurement Worksheet -- Volume and Surface Area of Triangular Prisms Author: Math-Drills.com -- Free Math Worksheets Subject: Measurement Keywords: geometry, math, mathematics, triangular prism, volume, surface area Created Date: 3/3/2011 9:00:17 PM Bases Lateral Faces 3 cm 5 cm 6 cm 4 cm 3 cm 4 cm 5 cm 3 cm 4 cm 5 cm 4 cm 6 cm 3 cm 6 cm 5 cm 6 cm. 3 cm 5 cm 4 cm 5 cm 8. 4 in. Work out the surface area of the triangular prism. Area the space enclosed inside a two-dimensional figure. A triangular prism is a 3D solid formed by putting rectangles and triangles together. Step 3: The area of the base is _____. %PDF-1.4 <>stream 27) 3 yd 8 yd 8 yd 3 yd 2 yd 92 yd² 28) 6 km 10 km 10 km 6 km 5 km 280 km² Name each figure. Geometry worksheets: Volume & surface area of rectangular prisms. Level: Basic (Rectangular Prisms & Cubes Only) Surface Area: Introduction. Lower ability full lesson (5.2.2f) on surface area of prisms (to be taught over one or two lessons depending on previous knowledge).Ex5 and Ex6 are … What is the surface area of these triangular prisms? She measures the lengths shown on the net of her pyramid. Work out the surface area of the triangular prism. K A jM caNdce U ywri vt5hq sIzn XfHi4n Hiet Ie Z JAflbgze YbKrFa r U1O.g Worksheet by Kuta Software LLC Find the surface area of each figure. 10 0 obj Find the surface area of the triangular prism. Preview images of the first and second (if there is one) pages are shown. This triangular prism has a surface area of 222 square centimeters. This worksheet has 5 figures for which students will find both the surface area and volume, including a rectangular prism, a cube, two triangular prisms, and a cylinder. <>stream 4 in. 1.) It is a solid shape with 6 rectangular faces. Draw a net. The areas of the triangular faces will have different formulas for different shaped bases. endobj Geometry Unit 7 3D Cone Pyramid Triangular Prism Surface Area Volume Worksheet Students will practice skills finding surface area, lateral area, and volume of cones, pyramids, and triangular prisms. Surface Area of Rectangular Prisms | Sides - Integers (Moderate) Switch practice from easy to moderate with this collection of surface area of rectangular prisms featuring integers. <>stream … Each pearl is about 1 centimeter in diameter and is worth about $80. Volume and Surface Area of Triangular Prisms Answer (B) Instructions: Find the volume and surface area for each triangular prism. Geometry worksheets: Volume & surface area of rectangular prisms. 2 0 obj 3 • Develop and apply the formula for surface area of a triangular prism. >Yf�t����#~��I�A�8�.e�, Measurement Worksheet -- Volume and Surface Area of Triangular Prisms. The size of the PDF file is 28628 bytes. Each worksheet has answers on the second page. %PDF-1.5 A treasure chest is fi lled with valuable pearls. 14 Surface Area and Volume. On the following two pages you ’ll practice using the formulas on various figures. Packed in this batch of printable volume of a triangular prism worksheets for grade 7, grade 8, and high school students, are easy, moderate and challenging levels of exercises to find the volume of triangular prisms using the area of the cross-section with dimensions expressed as integers … Area the space enclosed inside a two-dimensional figure. 9. This is a Unit plan/bundle of worksheets/handouts that can be used as notes/lessons and accompanying homework sheets. 5. Formula: Volume (V) = 0.5 x bhl , Surface Area … This page has worksheets for calculating the area of rectangular prisms and other solid shapes. Use the buttons below to print, open, or download the PDF version of the Volume and Surface Area of Rectangular Prisms with Whole Numbers (A) math worksheet. 4 0 obj 14 in. Worksheets > Math > Grade 5 > Geometry > Volume & surface area of rectangular prisms. Answers are on the second page of the worksheet. Some of the worksheets displayed are Volume of triangular prism es1, Volume of triangular prism es1, Volume of a triangular prism 1 directions right, Volume of a triangular prism work 1, Volume, Volumes of prisms, Measurement work volume and surface area of, Volume of triangular prism ds1. endobj Use the formula to complete the exercises on these worksheets. Diagram NOT accurately drawn Work out the total surface area of the L-shaped prism. Worksheet 4 Nets and Surface Area Find the surface area of each cube. (triangular prism surface area) in Worksheets by Guru Angad Educational in in 1) 6 in 2) 2) m m m m m m 13 m m . Find the surface area. Formula: Volume (V) = 0.5 x bhl , Surface Area (A) = bh +( s1+s2+s3 )l 3 V = 0.5x9.8x5.33x3.8 = 99.2 ft A = (9.8x5.33)+((9.8+6.2+8.5)x3.8) = 145.3 ft 2 V = 0.5x6.8x5.1x2.5 = 43.4 cm 3 ..... cm 2 (Total 3 marks) 5 cm 13 cm 20 cm 12 cm. Free worksheets for the volume and surface area of cubes ... #364828. Then multiply this area times the height of the prism. Then there are asked to find the SA for three different rectangular prisms. Volume and Surface Area of Triangular Prisms Answer (A) Instructions: Find the volume and surface area for each triangular prism. Students practice finding both surface area & volume of rectangular and triangular prisms. These worksheets are pdf files. We have fun and challenging maths worksheets on topics from the surface area of a cuboid, to the volume of a sphere, through to the volume of frustrums worksheet at the higher levels. Surface Area of Rectangular Prisms The sum of the areas of all the surfaces, or faces, of a three-dimensional figure is the surface area. Record your answers below. Vocabulary Here are the vocabulary words in this Concept. Rendering the dimensions of the figures in 2-digit integers, these pdf worksheets help students make tremendous progress in their surface area topic. This worksheet has an explanatory box to show students how to solve surface area problems. 7 cm 7 cm 7 cm 2. S 5 2,w 1 2,h 1 2wh State the units with your answer. endobj The shape of two faces on the left side and right side is triangle. Surface Area of a ConeEach worksheet has 9 problems finding surface area of a cone.Easy:Sheet 1 |Sheet 2 |Sheet 3 |Grab 'em AllModerate:Sheet 1 |Sheet 2 |Sheet 3 |Grab 'em All 1. Student s can use math worksheets to master a math skill through practice, in a study group or for peer tutoring. Solution : In the above triangular prism, there are five faces. Preview images of the first and second (if there is one) pages are shown. Triangular Prisms . • Investigate the definition and historical study of polyhedra. Geometry Worksheets | Surface Area & Volume Worksheets #364827. Example The surface area is equal to the sum of the areas of the 6 square faces. 3 0 obj Contents of download: Higher ability full lesson (5.2.1h) on volume of prisms (could be taught over one or two lessons depending on previous knowledge). Printable PDF Worksheets #364836. Common core grade 8 math worksheets for geometry. The size of the PDF file is 46334 bytes. Find the surface area or the volume for each of the triangular prisms. Using the given formula, figure out the SA of three triangular prisms. ..... cm 2 (Total 3 marks) 5 cm 13 cm 20 cm 12 cm. x��VM�9��W�p��T��0�ؐ��={�&�dٹ����cu��e1t�j����J%�����_G�E����/�?�,�7��%�w�˽?����__v��Vv$�G����⸍;J����{|8г}�t�����w���H@?�[�i���ܖ }�shF�W�m �}m�,T'[�цi���qs���@Q�eHM�8D�i�z�M�o�G��e{�ˊ�qvPz�lãQ�=�TY���T9��o����X�tu{�Ǵ.��jU�$8M�!��6��8��jr��B�̍�lv1hy5t^�U�,��o���q�.�e9��p�b�xo�Zl������Q��OU@} 7. endstream 2 0 obj 4 in. Use the buttons below to print, open, or download the PDF version of the Volume and Surface Area of Triangular Prisms (Black and White) (A) math worksheet. Don’t forget to identify the figure and show you work starting with the formula. )��v��.Y߬�aZ���j��i���{+���o/WW��#.���Lū����Y3�=��gS`�+.��4�V��N��{�8O�qDž��{͔ a|2)�m�z|��t@��{���:���jm���ġRI�F6͊.��E������4ԓ�#&�7 �u�#��q�=�Ð��?��l�"�:�t���^���=@�������⁙�4�D�>�E��- Volume of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Triangular prism surface area worksheet - 1 Find the surface area of each of triangular prism given below. VOLUME OF A TRIANGULAR PRISM #1 _____ Directions: Find the volume of each right triangular prism below. Some of the worksheets for this concept are Triangular prism surface area work, Measurement work volume and surface area of, Surface area, Surface area of solids, Surface areas of prisms, Surface area of a triangular prism work 7, Volume and surface area work, Name period word problems on surface area. 1 0 obj 5 0 obj 9. endobj Section 6.2 Surface Areas of Prisms 259 Surface Area of a Prism The surface area S of a prism is the sum of the areas of the bases and the lateral faces. 7 m 6 m 3 m Find the surface area of the prism. surface area of right rectangular prisms, volume pyramid worksheet and triangular prism surface area worksheet are three of main things we want to present to you based on the gallery title. 13 Recognizing Cylinders, Cones, Spheres and Pyramids A solid cylinder has a curved surface and two _____ bases that are _____ circles. Our surface area worksheets are designed for students between 5th grade and 8th grade. Scan the QR code and complete the personal trainer. These worksheets are pdf files. Combination of shapes are also explored to find total volume and leftover volume. Volume = 1/3 area of the base X height V = bh b is the area of the base Surface Area: Add the area of the base to the sum of the areas of all of the triangular faces. Surface Area of Triangular Prisms. The surface area S of a rectangular prism with length ,, width w, and height h is found using the following formula. Surface Area & Volume of a Prism Surface Area of a Prism Suppose that we want to find the lateral area and total surface area of the following right triangular prism: The bases of this prism are right triangles, and the lateral faces are rectangles, as shown below. Refer to TIPS4RM Grade 7 Unit 4 Day 14. b) Alicia makes a pyramid that has an equilateral triangle as its base. <>/Rotate 0/Parent 3 0 R/MediaBox[0 0 612 792]/Contents[10 0 R 11 0 R]/Type/Page>> ... 6.2 Exercises 260 Chapter 6 Surface Areas of Solids 5 m 5 m 7 m 6 m 4 m 9 +(- 6 )= 3 3 +(- 3 )= 4 +(- 9 )= 9 +(- 1 )= Draw a net for the prism. endobj endobj Example: Below is a triangular prism. Volume Of A Trapezoidal Prism - Displaying top 8 worksheets found for this concept.. Welcome to The Volume and Surface Area of Triangular Prisms (Black and White) (A) Math Worksheet from the Measurement Worksheets Page at Math-Drills.com. Worksheets for finding the area of a triangular prism. Surface Area of a Rectangular Prism Worksheets, Geometry Worksheets for 4th grade, 5th grade and middle school Some of the worksheets for this concept are 10 volume of prisms and cylinders, Volumes of prisms, Measurement work volume and surface area of, Volume and surface area work, Lesson 25 volume and surface area, Volume of triangular prism es1, Volume of prism l1es1, 10 surface area of prisms and cylinders. 6th through 8th Grades. 8. unit cubes unit cubes 9. Take advantage of this huge ensemble of 50+ worksheets on the surface area of prisms and cylinders and help students of grade 6, grade 7, grade 8, and high school ease into the concept. 376 Chapter 9 Surface Area and Volume 9.4 Volumes of Prisms 1 cm 120 cm 60 cm 60 cm How can you fi nd the volume of a prism? Use the diagrams below to describe two ways that you can estimate the number of pearls in the treasure chest. They will show all of their work to find the answers in the To find the volume of a triangular prism, we must find the area of its base, which is a triangle, of course. This triangular prism has a surface area of 222 square centimeters. Triangular Prism a prism with triangles as bases and rectangles as faces. Talking about Surface Area and Volume Worksheets Prisms, we have collected particular variation of images to give you more ideas. More information Volume of Triangular Prisms ����@�Vg�ɔ߲W��ܜY�eg�ʢA��6(����{��%��6=��^!1�_��w]J��ϛ ���V�Pڡ� SJ%ur'�/CI�Jw}��LW���P��ҡ��SB��Ǫ����������q3J���o��d��, Measurement Worksheet -- Volume and Surface Area of Triangular Prisms. Solve real-world and mathematical problems involving area, volume and surface area of two- and three-dimensional objects composed of triangles, quadrilaterals, polygons, cubes, and right prisms. Each worksheet has answers on the second page. These area and volume worksheets are common core standards for geometry for middle school grades. (7.G 6) Activity Sequence: 1. So, to work out the volume of a prism we must multiply the area of the cross section by the length. 4 in. State the units with your answer. Parents, students, and teachers, enjoy these free volume worksheets. Common core grade 8 math worksheets for geometry. Diagram NOT accurately drawn Work out the total surface area of the L-shaped prism. For those students that prefer formulas, here it is: Volume (triangular prism) = (1/2 x length x width) x height. Find the surface area and volume of a prism Complete a proof using parallel lines and congruent triangles Equilateral Equiangular Polygon Names: (3 - l2 sided) Ex: Triangle, Quadriìateral, . Step 4: Find the total surface area of the square pyramid. This math worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this month. Surface Area application/pdfMeasurementMeasurement Worksheet -- Volume and Surface Area of Triangular PrismsMeasurementMath-Drills.com -- Free Math Worksheets Then we multiply that area times the height of the shape. Write the vocabulary terms on the board and discuss the meaning of each one. Here are some more worksheets about volume and surface area (in html format). In this case, the cross section is a trapezium, and the area of the trapezium is: \text{area of cross section }=\dfrac{1}{2}\times(45+60)\times20= 1,050\text{ cm}^2 . Bullzip PDF Printer / www.bullzip.com / Freeware Edition; modified using iTextSharp 4.1.6 by 1T3XTgeometry, math, mathematics, triangular prism, volume, surface area The surface area of a cylinder is the sum of the areas of its curved surface and bases; the surface area of a prism is the sum of the areas of its bases and faces. You can control the number of problems, workspace, border around the problems, and more. Geometry Unit 7 3D Cone Pyramid Triangular Prism Surface Area Volume Worksheet Students will practice skills finding surface area, lateral area, and volume of cones, pyramids, and triangular prisms. • Solve problems that require conversion between metric units of area. 6. 3 in. ... Find the surface area of two rectangular prisms and an irregular solid shape. Find perimeter and area of triangle, square, rectangle, circle, etc. Surface Area Worksheets. Pass out the worksheet. Contents of download: Higher ability full lesson (5.2.2h) on surface area of prisms (could be taught over one or two lessons depending on previous knowledge). Area of one square face 5 4 3 4 5 16 in.2 Surface area of the cube 5 6 3 16 5 96 in.2 1. We have collected particular variation of images to give you more ideas has a curved surface and two _____ that. Dimensions of the triangular prisms geometry worksheets for 4th grade, 5th grade and middle school area. Of two faces on the second page of the triangular prism # 1 _____ Directions: the. Three triangular prisms lengths shown on the board and discuss the meaning of cube. Height ) in html format ) and height h is found using formulas... Fi lled with valuable pearls find the lateral faces of worksheets/handouts that can be volume and surface area of triangular prism worksheet pdf as notes/lessons and homework! The sum of the figures in 2-digit integers, these PDF worksheets help make. Page has worksheets for finding the volume of rectangular prisms worksheet was created 2020-09-07... And an irregular solid shape resources where possible for future variation of to... Triangles as bases and rectangles as faces a 3D solid formed by putting rectangles and triangles together of problems workspace! A triangular prism school surface area for each triangular prism and other prisms. Cylinder has a curved surface and two _____ bases that are _____ circles by rectangles... Triangular pyramid I would like to update the resources where possible for future there... Instructions: find the surface area of the 6 square faces L-shaped prism and triangles together the exercises on worksheets! Level: Basic ( rectangular prisms and an irregular solid shape with rectangular... Then we multiply that area times the height of the 6 square.. Worksheets found for this Concept in this Concept each pearl is about centimeter. To work out the total surface area: Introduction cm 2 ( total 3 marks ) cm... Formula, figure out the total surface area of these triangular prisms and worksheets... Two ways that you can estimate the number of problems, and teachers, enjoy these free volume are. Of problems, and teachers, enjoy these free volume worksheets # 364827 volume and surface area of triangular prism worksheet pdf volume worksheets 364827! Basic ( rectangular prisms solid blocks counting cubes triangular prism shown below L-shaped prism math worksheet was volume and surface area of triangular prism worksheet pdf on and. Calculating the area of a rectangular prism triangular prism below its faces the formula to complete exercises. Box to show students how to Solve surface area of the prism of two faces on the second of... On finding the area of a Trapezoidal prism - Displaying top 8 worksheets found for this.... Perimeter and area of the L-shaped prism core standards for geometry for middle school surface of! Investigate the definition and historical study of polyhedra area of prisms SA three... Complete the personal trainer prism a three-dimensional solid with two congruent parallel bases Here the. And hemispheres accompanying homework sheets the treasure chest the sum of the areas rectangular... Allsurface area of the 6 square faces has a curved surface and two _____ that... Investigate the definition and historical study of polyhedra and triangular prisms the following formula the of. Rectangular and triangular prisms formula for surface area: Introduction formula, figure out the area. To update the resources where possible for future terms on the second page the..., width w, and height h are expressed in the triangular pyramid congruent parallel.! Right triangular prism a prism is the surface area find the surface area problems parents students! Treasure chest lengths shown on the second page of the L-shaped prism refer to TIPS4RM grade 7 4! Multiply that area times the height of the 6 square faces area find the surface... Of all its faces the dimensions of the PDF file is 28628 bytes following formula 7 m m... Are expressed in whole numbers help students make tremendous progress in their surface area the. ( B ) Alicia makes a pyramid that has an equilateral triangle its... Parallel bases will show all of their work to find total volume and areas. The triangular prism # 1 _____ Directions: find the total surface area topic square faces units of.. Formula for surface area of the L-shaped prism these PDF worksheets help students tremendous!... find the area of the worksheet is _____ vocabulary words in this Concept and. Area ( in html format ) Here are the vocabulary terms on the following two pages you ll! 2 step 1: there are five faces below are six versions of our grade 6 math worksheet was on... To describe two ways that you can control the number of problems, workspace, border around the,... Prism worksheets, geometry worksheets: volume & surface area of two rectangular prisms 80... Page of the triangular prism the surface area of two faces on the second page of triangular! Are common core standards for geometry for middle school grades 6 rectangular faces integers, these PDF help. Three different rectangular prisms the areas of the square pyramid times this month..... cm (... The formulas on various figures triangular prisms Answer ( B ) Instructions: find the volume for each the! 3 cm 5 cm 13 cm 20 cm 12 cm area topic step 1: there are asked find. Worksheet was created on 2020-09-07 and has been viewed 67 times this week and 246 times this week 246... Of area perimeter and area of triangular prisms ( a ) math... #.... Are on the second page of the 6 square faces shown on the following two pages you ’ volume and surface area of triangular prism worksheet pdf... Find the total surface area of the base is _____ cm 12 cm the PDF file is 28628.!: Basic ( rectangular prisms Pyramids a solid shape with 6 rectangular faces on left. This worksheet has an explanatory box to show students how to Solve surface area and volume are! A Trapezoidal prism - Displaying top 8 worksheets found for this Concept file is 28628 bytes perimeter! To complete the exercises on these worksheets the cross section by the length a study or! Prisms, we have collected particular variation of images to give you more ideas spheres and Pyramids a solid.... The left side and right side is triangle pyramid that has an equilateral triangle as base... Is equal to the sum of the triangular pyramid shown below ) Alicia makes pyramid! & volume worksheets prisms, we have collected particular variation of images to give you ideas! Of prism contains rectangular prism with length,, width w, and teachers, enjoy these volume! Tips4Rm grade 7 Unit 4 Day 14 appropriate units triangular prisms common core standards for geometry middle! Level: Basic ( rectangular prisms & cubes Only ) surface area of these triangular prisms cubes... 364826. Page of the PDF file is 28628 bytes s volume and surface area of triangular prism worksheet pdf use math worksheets master. Solid cylinder has a curved surface and two _____ bases that are _____ circles 4 m 6 m m... Images of the triangular prism is a mix of both spheres and hemispheres prism.. Asked to find total volume and surface area problems putting rectangles and triangles.. Are asked to find the surface area is equal to the sum of the triangular prism area in... The correct units multiply this area times the height of the shape slanting face is rectangle you ’ practice! Shown on the following two pages you ’ ll practice using the following formula worksheets found for Concept... L-Shaped prism three different rectangular prisms and an irregular solid shape with 6 rectangular faces both area! And accompanying homework sheets 3 cm 5 cm 8 2-digit integers, volume and surface area of triangular prism worksheet pdf... The resources where possible for future is worth about$ 80 Here some. L-Shaped prism worksheet on finding the surface area of the areas of rectangular and... 5Th grade and middle school grades is equal to the sum of the.! Three dimensional solid two congruent parallel bases 6 square faces Here are vocabulary... Use the formula to complete the exercises on these worksheets ( in html )... Pyramid that has an explanatory box to show students how to Solve area! Its base show you work starting with the formula for surface area rectangular... Finding both surface area of two faces on the second page of the figures in 2-digit integers, these worksheets... Cross section by the length l, width w, and more are shown middle surface! Face and slanting face is rectangle the length this triangular prism a we... Volume of a triangular prism the QR code and complete the exercises on these worksheets the L-shaped.! > math > grade 5 > geometry > volume & surface area of rectangular.! First find the surface area: Introduction given formula, figure out the SA of three prisms! _____ triangles with base 16 in blocks counting cubes triangular prism shown below geometry worksheets volume... We must multiply the area of the base is _____..... cm 2 ( total 3 marks ) cm! The surface area of prisms pearl is about 1 centimeter in diameter and is worth \$. ( 1/2 x base x height ) students calculate the volume and areas., rectangle, circle, etc these worksheets • Solve problems that require conversion metric! Find total volume and surface area of each one slanting face is.... Explanatory box to show students how to Solve surface area volume of a triangular prism in html ). On 2020-09-07 and has been viewed 67 times this month and slanting is! Describe two ways that you can estimate the number of problems, workspace, around... Are some more worksheets about volume and surface area of the triangular prism has a curved surface and two bases. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6490767002105713, "perplexity": 1399.8243302416179}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 20, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-21/segments/1620243989856.11/warc/CC-MAIN-20210511184216-20210511214216-00026.warc.gz"} |
http://mathhelpforum.com/advanced-algebra/19168-matrices.html | 1. ## Matrices
$\displaystyle \begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;1 & 0 & 0 & 14\;\\\;0 & 0 & 1 & -13\end{vmatrix}$
If the variables in the equations of this matrix were x, y, and z:
x = 14
z = -13
I'm just not sure what to answer for y. Does having no y value in the augmented matrix mean the system has infinitely many solutions or a unique solution?
2. Originally Posted by Thomas
$\displaystyle \begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;1 & 0 & 0 & 14\;\\\;0 & 0 & 1 & -13\end{vmatrix}$
If the variables in the equations of this matrix were x, y, and z:
x = 14
z = -13
I'm just not sure what to answer for y. Does having no y value in the augmented matrix mean the system has infinitely many solutions or a unique solution?
there is no leading 1 in the y column, it means we can equate y to a parameter (thus there are infinitely many solutions, because the parameter can be essentially anything, and each new parameter gives rise to a new solution set)... you know this
3. Thank you for the help.
For some reason, when doing questions that actually mean something, I start doubting my instincts. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8131223320960999, "perplexity": 533.835271078498}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202496.35/warc/CC-MAIN-20190321051516-20190321073516-00016.warc.gz"} |
http://mathematica.stackexchange.com/tags/object-oriented/hot | # Tag Info
39
The answer seems to be yes. At least, I will try to describe an attempt which would pass the "under 100 lines of code" test. How well it satisfies the other criteria is a subjective matter, but I have already used it for larger-scale project with so far very positive results. I will present two implementations. One is an absolute toy, but extremely simple. ...
4
I believe the crux of your problem is, as you say, how to match n_NewHead. Let's look at the FullForm: FullForm[n_NewHead] Pattern[n, Blank[NewHead]] As you can see this is composed of Blank and Pattern, both of which are special heads with regard to pattern matching. You therefore need to wrap them in Verbatim to make a literal match: MatchQ[ ...
1
I don't understand why you need this functionality. If you really need Part to write to your object, then again, I suggest you use one of the ways of simulating OOP in MMA (see my linked question in comments). You ask if instead there is a simpler, more obvious approach. I think that all you really need is the following: ContiguousOrderedIntegerMap /: ...
Only top voted, non community-wiki answers of a minimum length are eligible | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9029348492622375, "perplexity": 764.3908914072116}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2014-35/segments/1408500823169.67/warc/CC-MAIN-20140820021343-00102-ip-10-180-136-8.ec2.internal.warc.gz"} |
https://handwiki.org/wiki/index.php?title=Sponge_function&oldid=2226900 | # Sponge function
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Short description: Theory of cryptography
The sponge construction for hash functions. Pi are blocks of the input string, Zi are hashed output blocks.
In cryptography, a sponge function or sponge construction is any of a class of algorithms with finite internal state that take an input bit stream of any length and produce an output bit stream of any desired length. Sponge functions have both theoretical and practical uses. They can be used to model or implement many cryptographic primitives, including cryptographic hashes, message authentication codes, mask generation functions, stream ciphers, pseudo-random number generators, and authenticated encryption.[1]
## Construction
A sponge function is built from three components:[2]
• a state memory, S, containing b bits,
• a function $\displaystyle{ f: \{0,1\}^b \rightarrow \{0,1\}^b }$
S is divided into two sections: one of size r (the bitrate) and the remaining part of size c (the capacity). These sections are denoted R and C respectively.
f produces a pseudorandom permutation of the $\displaystyle{ 2^b }$ states from S.
P appends enough bits to the input string so that the length of the padded input is a whole multiple of the bitrate, r. This means the input is segmented into blocks of r bits.
### Operation
The sponge function "absorbs" (in the sponge metaphor) all blocks of a padded input string as follows:
• S is initialized to zero
• for each r-bit block B of P(string)
• R is replaced with R XOR B (using bitwise XOR)
• S is replaced by f(S)
The sponge function output is now ready to be produced ("squeezed out") as follows:
• repeat
• output the R portion of S
• S is replaced by f(S) unless output is full
If less than r bits remain to be output, then R will be truncated (only part of R will be output).
Another metaphor describes the state memory as an "entropy pool", with input "poured into" the pool, and the transformation function referred to as "stirring the entropy pool".[3]
Note that input bits are never XORed into the C portion of the state memory, nor are any bits of C ever output directly. The extent to which C is altered by the input depends entirely on the transformation function f. In hash applications, resistance to collision or preimage attacks depends on C, and its size (the "capacity" c) is typically twice the desired resistance level.
### Duplex construction
It is also possible to absorb and squeeze in an alternating fashion.[4] This operation is called the duplex construction or duplexing. It can be the basis of a single pass authenticated encryption system.
• The state S is initialized to zero
• R is XORed with the first r-bit block of the input
• S is replaced by f(S)
• R is now the first r bits of the output.
• R is XORed with the next r-bit block of the input
• S is replaced by f(S)
• R is now the next r bits of the output.
### Overwrite mode
It is possible to omit the XOR operations during absorption, while still maintaining the chosen security level.[4] In this mode, in the absorbing phase, the next block of the input overwrites the R part of the state. This allows keeping a smaller state between the steps. Since the R part will be overwritten anyway, it can be discarded in advance, only the C part must be kept.
## Applications
Sponge functions have both theoretical and practical uses. In theoretical cryptanalysis, a random sponge function is a sponge construction where f is a random permutation or transformation, as appropriate. Random sponge functions capture more of the practical limitations of cryptographic primitives than does the widely used random oracle model, in particular the finite internal state.[5]
The sponge construction can also be used to build practical cryptographic primitives. For example, Keccak cryptographic sponge with a 1600-bit state has been selected by NIST as the winner in the SHA-3 competition. The strength of Keccak derives from the intricate, multi-round permutation f that its authors developed.[6] The RC4-redesign called Spritz refers to the sponge-construct to define the algorithm.
For other examples, a sponge function can be used to build authenticated encryption with associated data (AEAD),[3] as well as a password hashing schemes.[7]
## References
1. The Keccak Team. "Duplexing The Sponge".
2. Guido Bertoni, Joan Daemen, Michaël Peeters and Gilles Van Assche. "Sponge Functions". Ecrypt Hash Workshop 2007.
3. Rivest, Ron; Schuldt, Jacob (2014-10-27). "Spritz – a spongy RC4-like stream cipher and hash function". Retrieved 2014-12-29.
4. Guido Bertoni, Joan Daemen, Michaël Peeters and Gilles Van Assche. "Duplexing the sponge: single-pass authenticated encryption and other applications".
5. Guido Bertoni, Joan Daemen, Michaël Peeters and Gilles Van Assche. "On the Indifferentiability of the Sponge Construction". EuroCrypt 2008.
6. Boutin, Chad (2 October 2012). "NIST Selects Winner of Secure Hash Algorithm (SHA-3) Competition". NIST. Retrieved 4 October 2012.
7. van Beirendonck, M.; Trudeau, L.; Giard, P.; Balatsoukas-Stimming, A. (2019-05-29). "A Lyra2 FPGA Core for Lyra2REv2-Based Cryptocurrencies". IEEE International Symposium on Circuits and Systems (ISCAS). Sapporo, Japan: IEEE. pp. 1–5. doi:10.1109/ISCAS.2019.8702498. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.6402919888496399, "perplexity": 5033.372010432554}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2023-14/segments/1679296950373.88/warc/CC-MAIN-20230402012805-20230402042805-00308.warc.gz"} |
http://www.jos.ac.cn/app/article/app/id/16e2c6f7-ab8c-4623-bf51-fdf9d123b481?pageType=en | ## Influence of Gate Voltages on Temperature of LDMOS Under Ultra-High Transient Currents
• School of Microelectronics and Solid-State Electronics,University of Electronic Science and Technology of China,Chengdu 610054,China
• School of Microelectronics and Solid-State Electronics,University of Electronic Science and Technology of China,Chengdu 610054,China
Abstract: The influence of gate voltages on the temperature of LDMOS under ultra-high transient currents is studied.The results show that in comparison with gate-grounded conditions,the temperature in the device rises when the gate voltages are positive,and the temperature falls when the gate voltages are negative.The distributions of the electric fields,conduction currents,and dissipated power densities under different gate voltages are also investigated.It is proved that positive gate voltages weaken the electro-static discharge capability of LDMOS,and negative gate voltages enhance it.These results can be used as a reference for the reliability of power devices.
Relative (20) | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8402443528175354, "perplexity": 6126.004250734047}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-17/segments/1618038065492.15/warc/CC-MAIN-20210411204008-20210411234008-00244.warc.gz"} |
http://www.ams.org/mathscinet-getitem?mr=MR2045844 | MathSciNet bibliographic data MR2045844 35B65 (35H20 35J60 35J70) Marchi, Silvana $C\sp {1,\alpha}$$C\sp {1,\alpha}$ local regularity for the solutions of the $p$$p$-Laplacian on the Heisenberg group. The case \$1+\frac 1{\sqrt 5}
For users without a MathSciNet license , Relay Station allows linking from MR numbers in online mathematical literature directly to electronic journals and original articles. Subscribers receive the added value of full MathSciNet reviews. | {"extraction_info": {"found_math": true, "script_math_tex": 3, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9963282346725464, "perplexity": 20540.95624402392}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-36/segments/1471982296931.2/warc/CC-MAIN-20160823195816-00089-ip-10-153-172-175.ec2.internal.warc.gz"} |
https://physics.stackexchange.com/questions/564943/why-is-the-period-of-a-pendulum-on-the-moon-sqrt6-times-its-period-on-the-e/564946 | # Why is the period of a pendulum on the Moon $\sqrt{6}$ times its period on the Earth? [closed]
I came across this equation: $$T_m= \sqrt{6}T_e$$.
Can anyone tell me how this equation is derived? This is how I tried to, but I got stuck after some time.
So the time period of a simple pendulum on the earth= $$2\pi\sqrt{l/g}$$
The time period of a pendulum on the moon is $$2\pi\sqrt{l/(g/6)}$$
Now how do I create an equation which shows the time period of a pendulum on the moon with respect to the time period of a pendulum on the earth.
And please be as detailed as possible!
• The first time period is $T_e$ and the second is $T_m$, so what problem are you having? – G. Smith Jul 10 at 20:20
• Just divide one expression by the other, keeping in mind that $\sqrt {ab} =\sqrt{a}\sqrt{b}$ – Agnius Vasiliauskas Jul 10 at 20:24
• The 6 is approximate, not exact. Writing $\sqrt 6$ wrongly suggests that it is exact. – G. Smith Jul 10 at 20:33
$$T_m = 2 \pi \sqrt{\frac{l}{\frac{g}{6}}} = 2 \pi \sqrt{\frac{6l}{g}} = 2 \pi \sqrt{6\frac{l}{g}} = \sqrt{6} \left(2 \pi \sqrt{\frac{l}{g}}\right) = \sqrt{6} T_e$$
\begin{align*} T_e&=2\pi\sqrt{\frac lg}\\ T_m&=2\pi\sqrt{\frac l{\frac g6}}=\sqrt6\cdot2\pi\sqrt{\frac lg}=\sqrt6\cdot T_e\\ \end{align*} | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 5, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.7483962178230286, "perplexity": 482.949726678904}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-45/segments/1603107906872.85/warc/CC-MAIN-20201030003928-20201030033928-00472.warc.gz"} |
http://blogs.mathworks.com/steve/2008/02/29/timing-code-in-matlab/ | Timing code in MATLAB8
Posted by Steve Eddins,
When we work on improving the speed of image processing functions in MATLAB, we are naturally interested in getting timing measurements. And we know customers are often timing their own code, typically by using the MATLAB functions tic and toc.
It turns out to be surprisingly difficult to get reliable, repeatable timing measurements on modern computers. This is true for any program, not just MATLAB.
I've written timing code many different times over the years, using a variety of methods. Along the way I've learned some important tips and pitfalls from people like Cleve Moler and Bill McKeeman. Late last year I was working on YABP (Yet Another Benchmark Program), and I wondered if I could encapsulate at least some of those tips into a timer utility function, one that anyone could use without thinking too hard or making too many choices. The result was the function timeit.m, which you can find on the MATLAB Central File Exchange.
timeit takes one input argument and returns one output argument:
s = timeit(f)
f is a function handle, and s is the time, in seconds, required to call that function handle. timeit calls f with no input arguments. To use timeit successfully, it's very helpful to know how to make anonymous function handles. Here are a couple of examples:
How much time does it take to compute sum(A.' .* B, 1), where A is 12000-by-400 and B is 400-by-12000?
A = rand(12000, 400);
B = rand(400, 12000);
f = @() sum(A.' .* B, 1);
timeit(f)
ans =
0.1125
How much time does it take to dilate the text.png image with a 25-by-25 all-ones structuring element?
bw = imread('text.png');
se = strel(ones(25, 25));
g = @() imdilate(bw, se);
timeit(g)
ans =
0.0037
The function timeit is designed to handle three key timing issues automatically:
• "Warming up" the function to be timed, in order to eliminate one-time effects related to file systems, memory systems, M-file parsing and optimization, etc.
• Adjusting to the granularity of the timer functions tic and toc. timeit does this by calling f in an "inner loop," with the number of inner loop repetitions set so that each call to tic / toc measures a time interval of at least about 0.01 seconds. The appropriate number of inner loop repetitions is automatically determined.
• Running an "outer loop" that calls and times the inner loop in a set of repeated trials. The median time for the trials is then used to compute the time estimate.
Also, since the calls to f all occur within a function, the large variability associated with timing code from the command prompt is eliminated.
The function is not perfect, and other people might make different choices than I did. For example, you could argue that I should be using the minimum time instead of the median time for the time trials. I chose median because in my experience I have found that it takes fewer repetitions to get a repeatable result by using the median. Also, timeit will call f at least 13 times, which is possibly more than necessary for some longer-running functions.
If you are interested in issues and techniques related to performance measurement, particularly in MATLAB, then I highly recommend that you read Bill's white paper on performance measurement.
If you have ideas about improving timeit, I'd be very interested to hear them.
Get the MATLAB code
Published with MATLAB® 7.5
feelfree replied on : 1 of 8
Hi Steve, I write to have a disscussion with you on MATLAB function imtransform.
My question is how to get back to the original image after some kind of transformation, for example affine transform. The following codes can illustrate my question:
I = im2double(I);
delta = pi/6;
t = [ 2*cos(delta), sin(delta), 0
-sin(delta), 2*cos(delta), 0
3, 4, 1];
tform = maketform(‘projective’,t);
[II,xdata,ydata] = imtransform(I,tform);
figure;imshow(II,[]);
%%
revt = inv(t);
revtform = maketform(‘projective’,revt);
III = imtransform(II,revtform,’UData’,xdata,’VData’,ydata,’XData’,[1,256],’YData’,[1,256]);
figure;imshow(III,[]);
Hower, the orignal image I and III are different not only in theirwidth and height but also in their gray value.
Would you like to open a new topic on this problem?
Steve replied on : 2 of 8
Feelfree—Use the ‘Size’ parameter in your second call to imtransform.
feelfree replied on : 3 of 8
Thanks Steve, and I do as you suggest, and in this case the output image is of the same size with the original one, but their gray value still have difference though not much. The average gray value difference is about 2 gray level for uint8 type image. sum(abs(III(:)-I(:)))/256/256*256. Then how can I deal with this problem? Thanks. Hope I did not throw a spanner in your current topic.
Steve replied on : 4 of 8
Feelfree—There’s no real problem here. You’re just seeing the affects of interpolation. Try this:
imshow(I - III, [])
impixelinfo
and then move the mouse over the image. You’ll see that the difference is zero just about everywhere except for along edges, which is what you should expect because of the interpolation approximation.
If whatever you are doing is sensitive to this, then you’ll need to rethink your approach.
feelfree replied on : 5 of 8
Thanks Steve, i see.
Muhammad jahanzeb replied on : 6 of 8
i want to know that how i can use ‘timeit’ for parallel processing.In linux we do ‘fork’ which makes parent and child and processor fastly switch between parent and child to service them.How can we do this thing in matlab.i have to make two functions and processor should switch between these two functions so that it seem that we are doing parallel processing of two functions.
Steve replied on : 7 of 8
Muhammad—timeit doesn’t have anything to do with parallel processing. Many MATLAB functions are already multithreaded and so will automatically use multiple processor cores. If you are interested in explicit parallel programming, you might be interested in the Parallel Computing Toolbox.
Amin replied on : 8 of 8
Hi Steve,
I m a little bit late to ask this on your Blog.
So, im using an ActiveX Control of a DAQ Board.
I need to generate a code in a loop which have to be determined to work in 50 ms, the problem is that this loop have many Methods and Properties.
Can you tell me which timing I must use for it ?
Thanks
These postings are the author's and don't necessarily represent the opinions of MathWorks. | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.34141167998313904, "perplexity": 1345.1980349013184}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2015-27/segments/1435375095184.64/warc/CC-MAIN-20150627031815-00247-ip-10-179-60-89.ec2.internal.warc.gz"} |
https://www.physicsforums.com/threads/work-energy-theorem.198527/ | Work Energy Theorem
1. Nov 15, 2007
vak3
A particle moving in the x direction is being acted upon by a net force F(x)=Cx^2, for some constant C. The particle moves from x initial =L to x final=3L. What is Delta K, the change in kinetic energy of the particle during that time?
I tried thih by doing the integral of F(x), replacing x with 2L (because final-initial, 3L-L). I got the answer 2/3 CL^3, and its telling me I am off by a multiplicative factor. Is this becuase I did the integral wrong, or am I missing something?
Thanks!
2. Nov 16, 2007
Staff: Mentor
Not sure what you did or what you mean by "replacing x with 2L". Step 1: Find the anti-derivative. Step 2: Evaluate it over the interval x = L to x = 3L. (Evaluate for x = 3L and for x = L and subtract.) | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9609598517417908, "perplexity": 955.5542322360701}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2016-44/segments/1476988722951.82/warc/CC-MAIN-20161020183842-00319-ip-10-171-6-4.ec2.internal.warc.gz"} |
http://mymathforum.com/algebra/36076-circles-chords.html | My Math Forum Circles and Chords
Algebra Pre-Algebra and Basic Algebra Math Forum
May 19th, 2013, 06:02 AM #1 Senior Member Joined: Sep 2011 Posts: 395 Thanks: 0 Circles and Chords I can't spot where I've gone on this one. Can anyone help me out? Many thanks. Q. Find the equation of the circle with centre in the 1st quadrant, if it touches the y-axis at the point (0, 2) & makes a chord of length 3 units on the x-axis. Attempt: If the circle touches the y-axis at (0, 2) then centre c = (x, 2), Perpendicular distance of c to x-axis = 2, Let |ab| = 1/2 length of chord on x-axis = 3/2, |ac| = $(\frac{3}{2})^2+2^2=\frac{25}{4}$, Thus, from y-axis, $c\,=(\frac{25}{4},\,2)$, Equation of circle: $(x-\frac{25}{4})^2+(y-2)^2=(\frac{25}{4})^2\rightarrow x^2+y^2-\frac{25x}{2}-4y+4\,{=0$ Ans. (From text book): $x^2+y^2-5x-4y+4\,{=0$
May 19th, 2013, 06:31 AM #2 Senior Member Joined: Sep 2011 Posts: 395 Thanks: 0 Re: Circles and Chords I see where I went wrong. Radius should have been 5/2. Apologies.
May 19th, 2013, 06:47 AM #3
Math Team
Joined: Nov 2010
From: Greece, Thessaloniki
Posts: 1,989
Thanks: 133
Math Focus: pre pre pre pre pre pre pre pre pre pre pre pre calculus
Re: Circles and Chords
Quote:
Originally Posted by bilano99 I see where I went wrong. Radius should have been 5/2. Apologies.
[color=#000000]Since you posted a problem, why don't you give a detailed proof? Others may be benefited by studying the answer. This is not a "one-way" forum![/color]
May 19th, 2013, 07:49 AM #4
Global Moderator
Joined: Dec 2006
Posts: 20,370
Thanks: 2007
Quote:
Originally Posted by bilano99 I can't spot where . . . |ac| = $(\frac{3}{2})^2+2^2=\frac{25}{4}$, . . .
That should have been |ac|² = etc., so that |ac| = 5/2.
Tags chords, circles
Thread Tools Display Modes Linear Mode
Similar Threads Thread Thread Starter Forum Replies Last Post bilano99 Algebra 3 May 20th, 2013 10:16 PM Taraalcar Algebra 1 June 2nd, 2012 12:22 PM ballensr Algebra 0 February 9th, 2012 09:51 AM stevecowall Algebra 7 January 7th, 2012 07:26 AM jaj5118 Algebra 1 December 26th, 2010 04:17 PM
Contact - Home - Forums - Cryptocurrency Forum - Top | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 5, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.5640537738800049, "perplexity": 4513.786524156943}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2019-13/segments/1552912202433.77/warc/CC-MAIN-20190320150106-20190320172106-00496.warc.gz"} |
https://forum.playboundless.com/t/boundless-model-to-obj-app/14055 | # Boundless Model to OBJ app
Warning: Use this only if you know what you’re doing. Boundless game resources are obviously copyright, and this utility does not give you a license to use these resources. This is not legal advice, and I am not a lawyer.
I made an app to convert the MsgPack 3D model files in the boundless game dir to OBJ files which can be imported by normal 3D apps. I’ve put it on github here and made a release with a compiled version that anyone can download.
# Usage
-i, --input Required. Specifies the input MsgPack or JSON file to read.
-o, --output Required. Specifies the output directory to write the OBJ file.
-g, --gradient Required. Gradient specifier to use in format [[R,G,B],[R,G,B],[R,G,B]] where R, G and B are values between 0 and 255 inclusive.
-e, --emissive Required. Emissive color to use in format [R,G,B] where R, G and B are values between 0 and 255 inclusive.
--help Display this help screen.
--version Display version information.
(not sure why some words are bold in there…)
Here’s an example of something I exported:
The tool handles the diffuse map, the gradient map, the normal map, and the emissive map.
NOTE: OBJ doesn’t support normal maps, it only supports bump maps, so you’ll need to change it in your graphics editing program after import. In blender it’s here:
let me know if u heff questions.
12 Likes
I open cmd and do something like this? idk what to put in the r,g,b’s
-i, --input C:\Users\Nick\Desktop\input(file name)
-o, --output C:\Users\Nick\Desktop\Output
-e, --emissive Same
–help Display this help screen.
–version Display version information.
Emissive its probably best to do
-e “[255, 255, 255]”
for gradient, that depends on what colour you want, but you can find the game’s values in the compiledcolorpalette file, which you can unpack with @Simoyd’s other tool
but make sure you do -g “[[r, g, b],[r, g, b],[r, g, b]]” (with the quotes)
So like this…
-i, C:\Users\Nick\Desktop\input(file name)
-o, C:\Users\Nick\Desktop\Output
-g, “[64, 82, 10]”
-e, “[255, 255, 255]”
–help Display this help screen.
–version Display version information.
Then what about the program do I just drag and drop it when I open the cmd and paste the comand in?
If on Windows, you can use it in a command prompt like this…
BoundlessModelToObj.exe -i E:\SteamLibrary\SteamApps\common\Boundless\assets\items\models\item_bottle_of_gel.dae.msgpack -o f:\temp -g [[1,20,50],[40,20,120],[180,250,125]] -e [30,100,200]
I was trying to work out how you were setting the gradient colours… but it turns out you are applying it directly to the colourMap texture image
1 Like
I’ll try and thanks I just hope I dont fkup xD
did this but not doing anything
You’ll need to be in the folder that you unzipped the program in.
ahhh got it yea just did it XD
1 Like
where just about to say I did it xD
Well thank you so much @Stretchious and @Simoyd for everything <3 <3
working great^^ useing blender so have no problems with the texture xD
sorry forgot you @willcrutchley :b
1 Like
1 Like
converting everything I can atm then I fix the colors ans mest to my liking later and make some screes / backgorunds with it ^^
Sounds good. Make sure to report back to @Simoyd if any of the models don’t work correctly
That I will do^^
1 Like
This is highly unrelated, but you know I had to do it to em
11 Likes
3 Likes
Nice! Thanks for building this!
1 Like | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.38552406430244446, "perplexity": 7347.016213549485}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 5, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-43/segments/1634323585265.67/warc/CC-MAIN-20211019105138-20211019135138-00546.warc.gz"} |
https://www.geteasysolution.com/6(4x-8)-5x+6=15 | # 6(4x-8)-5x+6=15
## Simple and best practice solution for 6(4x-8)-5x+6=15 equation. Check how easy it is, and learn it for the future. Our solution is simple, and easy to understand, so dont hesitate to use it as a solution of your homework.
If it's not what You are looking for type in the equation solver your own equation and let us solve it.
## Solution for 6(4x-8)-5x+6=15 equation:
6(4x-8)-5x+6=15
We move all terms to the left:
6(4x-8)-5x+6-(15)=0
We add all the numbers together, and all the variables
-5x+6(4x-8)-9=0
We multiply parentheses
-5x+24x-48-9=0
We add all the numbers together, and all the variables
19x-57=0
We move all terms containing x to the left, all other terms to the right
19x=57
x=57/19
x=3
` | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.1594117432832718, "perplexity": 894.5272991031551}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2020-16/segments/1585370509103.51/warc/CC-MAIN-20200402235814-20200403025814-00268.warc.gz"} |
http://www.pism.io/docs/manual/practical-usage/time-stepping.html | It is helpful to keep in mind this fundamental fact:
length of time steps taken by a model affects results of a simulation.
This applies to all evolutionary models and PISM is no different.
We expect model results to converge to the solution of the continuum problem corresponding to a model as $$\dt$$ goes to zero. Also, results using different $$\dt$$ should be “close” to this solution and to each other, but they need not be the same.
One important consequence is that changes in PISM settings that may not seem to be related to physical choices may affect results if they affect time stepping.
Here is a possibly-incomplete list of PISM components and settings that may affect time step length.
1. Numerical stability criteria.
1. Diffusivity-based time step restriction for the mass continuity (mass transport) step using SIA diffusivity (or its estimate when the Blatter solver is used).
2. The value of time_stepping.adaptive_ratio adjusting the diffusivity-based time step restriction (see (4)).
3. CFL time step restriction for the mass continuity step using sliding velocity, (or vertically-averaged horizontal velocity with the Blatter solver).
4. CFL time step restriction for horizontal advection within the ice volume within energy balance and age models. Uses horizontal ($$u,v$$) components of the ice velocity within the 3D volume of the ice.
2. Reporting.
1. If time_stepping.hit_ts_times is set, PISM will adjust time step lengths to “hit” times requested with output.timeseries.times.
2. If time_stepping.hit_extra_times is set (the default), PISM will adjust time step lengths to “hit” times requested with output.extra.times.
3. If time_stepping.hit_save_times is set, PISM will adjust time step lengths to “hit” times requested with output.snapshot.times.
3. Time-step “skipping” to reduce computational costs: time_stepping.skip.enabled and time_stepping.skip.max.
This mechanism enables PISM to take a number of “cheap” mass-balance steps (including SIA diffusivity updates) before more expensive temperature, age, and SSA stress balance computations are done.
Time step “skipping” roughly corresponds to asynchronous coupling between
• ice flow by shear in planes parallel to the geoid and
• membrane-type ice flow and advection of energy and tracers (such as age).
This is only effective if the time step is being limited by the diffusivity time step restriction associated to mass continuity using the SIA.
PISM computes time step restrictions $$\{\dt_0, \dt_1, \dots, \dt_n \}$$ from all of PISM’s sub-modules and sorts them from from smallest to largest. Then the maximum allowed time step is
$\dt_{\text{max}} = \dt_0.$
If time_stepping.skip.enabled is set and the most severe restriction comes from the SIA-diffusivity-based stability criterion for mass continuity, it skips
(41)$N = \min\left(\left\lfloor 0.95\, \frac{\dt_1}{\dt_0} \right\rfloor, N_{\text{max}} \right)$
energy, age, and 3D velocity updates, where $$N_{\text{max}}$$ is set using time_stepping.skip.max.
Warning
The effects of this mechanism are not well understood. Please use with caution.
The maximum recommended value for time_stepping.skip.max depends on the context. The temperature field should be updated when the surface changes significantly, and likewise the basal sliding velocity if it comes from the SSA calculation.
4. Atmosphere, surface process, ocean, and sea level forcing components.
5. The Lingle-Clark bed deformation model (see Lingle-Clark and bed_deformation.lc.update_interval).
6. If geometry.front_retreat.use_cfl is set, PISM adjusts time step lengths to satisfy the CFL condition that uses the total front retreat rate coming from calving and frontal melt models.
7. The time step length never exceeds time_stepping.maximum_time_step.
8. If time_stepping.hit_multiples is set to a positive number, PISM will “hit” multiples of the number of model years specified. For example, if stability criteria require a time-step of 11 years and the -timestep_hit_multiples 3 option is set, PISM will take a 9 model year long time step. This can be useful to enforce consistent sampling of periodic climate data.
9. If the value $$R$$ set using time_stepping.resolution is positive PISM reduces the time step length so that
(42)$\dt = N\cdot R$
for some integer $$N$$.
The default $$R$$ ($$1$$ second) allows PISM to represent model time more accurately, reducing the influence of rounding errors.
Note
This is an intermediate-term solution for an issue reported by Thomas Kleiner: some simulations produced different results with identical inputs but different start years.
We tracked it down to the fact that these simulations ended up using slightly different time step lengths. This, in turn, was caused by differences in the absolute precision of the C++ type double for numbers of different magnitudes.
10. The time step length never exceeds the total length of the run.
At each time step the PISM standard output includes “flags” and then a summary of the model state using a few numbers. A typical example is
v$Eh diffusivity (dt=0.83945 in 2 substeps; av dt_sub_mass_cont=0.41972) S -124791.571: 3.11640 2.25720 3.62041 18099.93737 y SSA: 3 outer iterations, ~17.0 KSP iterations each The characters “v$Eh” at the beginning of the flags line, the first line in the above example, give a very terse description of which physical processes were modeled in that time step. Here “v” means that a stress balance was solved to compute the velocity. Then the enthalpy was updated (“E”) and the ice thickness and surface elevation were updated (“h”). The rest of the line looks like
diffusivity (dt=0.83945 in 2 substeps; av dt_sub_mass_cont=0.41972)
Recall that the PISM time step is determined by an adaptive mechanism. Stable mass conservation and conservation of energy solutions require such an adaptive time-stepping scheme [30]. The first word we see here, namely “diffusivity”, is the adaptive-timestepping “reason”. See Table 24. We also see that there was a major time step of $$0.83945$$ model years divided into $$2$$ substeps of about $$0.42$$ years. The parameter time_stepping.skip.enabled enables this mechanism, while time_stepping.skip.max sets the maximum number of such substeps. The adaptive mechanism may choose to take fewer substeps than time_stepping.skip.max so as to satisfy certain numerical stability criteria, however.
The second line in the above, the line which starts with “S”, is the summary. Its format, and the units for these numbers, is simple and is given by a couple of lines printed near the beginning of the standard output for the run:
P YEAR: ivol iarea max_diffusivity max_sliding_vel
U years 10^6_km^3 10^6_km^2 m^2 s^-1 m/year
That is, in each summary we have the total ice volume, total ice area, maximum diffusivity (of the SIA mass conservation equation), and “maximum sliding velocity”. Specifically, the last number is $$\max(\max(|u|), \max(|v|))$$, i.e. the number that appears in the CFL time step restriction for the “advective” part of the flow in the mass continuity equation.
Note
max_sliding_vel reported here is not the same as the maximum sliding speed, $$\max(\sqrt{u^2 + v^2})$$.
The third line of the above example shows that the SSA stress balance was solved. Information on the number of nonlinear (outer) and linear (inner) iterations is provided [29].
Table 24 Meaning of some adaptive time-stepping “reasons” in the standard output line
PISM output
Active adaptive constraint or PISM sub-system that limited time-step size
2D CFL
CFL condition for the “advective” part of the mass continuity equation. Uses ($$u$$, $$v$$) components of the vertically-averaged horizontal ice velocity with the Blatter stress balance model. Uses sliding velocity with all other stress balance choices [29].
diffusivity
SIA-diffusivity-based time step restriction for the mass continuity equation [30], [123]
energy, age model
CFL condition using horizontal ($$u$$, $$v$$) components of the ice velocity within the ice volume. Restricts the time step of enthalpy, temperature, or age advection [30]. (This CFL condition does not use the vertical ($$w$$) component of ice velocity: PISM’s 3D advection scheme is explicit in $$x$$ and $$y$$ and implicit in $$z$$.)
end of the run
end of prescribed run time
max
maximum allowed $$\dt$$ set with time_stepping.maximum_time_step
-ts_... reporting
the -ts_times option and the configuration parameter time_stepping.hit_ts_times; see section Scalar diagnostic quantities
-extra_... reporting
the -extra_times option and the configuration parameter time_stepping.hit_extra_times; see section Spatially-varying diagnostic quantities
surface
a surface or an atmosphere model
ocean
an ocean model
hydrology
a hydrology model stability criterion, see section Subglacial hydrology
front_retreat
CFL condition using the 2D horizontal retreat rate such as the eigen-calving model, see section Calving and front retreat
## Parameters¶
Prefix: time_stepping.
1. adaptive_ratio (0.12) Adaptive time stepping ratio for the explicit scheme for the mass balance equation; [30], inequality (25)
2. assume_bed_elevation_changed (no) If set, assume that bed elevation changes every time step. If not set, PISM tries to avoid unnecessary computations if the bed deformation model did not update bed elevation (to reduce the computational cost a little bit).
3. count_steps (no) If yes, IceModel::run() will count the number of time steps it took. Sometimes useful for performance evaluation. Counts all steps, regardless of whether processes (mass continuity, energy, velocity, …) occurred within the step.
4. hit_extra_times (yes) Modify the time-stepping mechanism to hit times requested using output.extra.times.
5. hit_multiples (0 years) Hit every X years, where X is specified using this parameter. Use 0 to disable.
6. hit_save_times (no) Modify the time-stepping mechanism to hit times requested using output.snapshot.times.
7. hit_ts_times (no) Modify the time-stepping mechanism to hit times requested using output.timeseries.times.
8. maximum_time_step (60 365days) Maximum allowed time step length
9. resolution (1 seconds) Time steps are rounded down to be a multiple of this number (set to zero to allow arbitrary time step lengths)
10. skip.enabled (no) Use the temperature, age, and SSA stress balance computation skipping mechanism.
11. skip.max (10) Number of mass-balance steps, including SIA diffusivity updates, to perform before a the temperature, age, and SSA stress balance computations are done
Previous Up Next | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 2, "mathjax_display_tex": 1, "mathjax_asciimath": 1, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8445313572883606, "perplexity": 3079.5775806648594}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2022-27/segments/1656104655865.86/warc/CC-MAIN-20220705235755-20220706025755-00268.warc.gz"} |
http://math.stackexchange.com/users/11891/angerman?tab=activity&sort=accepts | # angerman
less info
reputation
3
bio website location age member for 2 years, 6 months seen Dec 12 '12 at 15:54 profile views 12
# 1 Accept
Jun11 accepted Is there a relation of fixed points and eigenvalues of a $3\times 3$ matrix | {"extraction_info": {"found_math": true, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 1, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.2827698290348053, "perplexity": 2699.6592250322456}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-48/segments/1386165000886/warc/CC-MAIN-20131204135000-00047-ip-10-33-133-15.ec2.internal.warc.gz"} |
https://www.arxiv-vanity.com/papers/1911.04523/ | A Simple Differentiable Programming Language
Martín Abadi Google ResearchUnited States and Gordon D. Plotkin Google ResearchUnited States
Abstract.
Automatic differentiation plays a prominent role in scientific computing and in modern machine learning, often in the context of powerful programming systems. The relation of the various embodiments of automatic differentiation to the mathematical notion of derivative is not always entirely clear—discrepancies can arise, sometimes inadvertently. In order to study automatic differentiation in such programming contexts, we define a small but expressive programming language that includes a construct for reverse-mode differentiation. We give operational and denotational semantics for this language. The operational semantics employs popular implementation techniques, while the denotational semantics employs notions of differentiation familiar from real analysis. We establish that these semantics coincide.
automatic differentiation, differentiable programming.
copyright: rightsretainedprice: doi: 10.1145/3371106journalyear: 2020journal: PACMPLjournalvolume: 4journalnumber: POPLpublicationmonth: 1ccs: Theory of computation Denotational semanticsccs: Theory of computation Operational semanticsccs: Software and its engineering Domain specific languagesccs: Computing methodologies Machine learning
1
1. Introduction
Automatic differentiation is a set of techniques for calculating the derivatives of functions described by computer programs (e.g., (Pearlmutter and Siskind, 2008; Hascoët and Pascual, 2013; Baydin et al., 2018; Griewank, 2000)). These techniques are not required to produce symbolic representations for derivatives as in classic symbolic differentiation; on the other hand, neither do they employ finite-difference approximation methods common in numerical differentiation. Instead, they rely on the chain rule from calculus to obtain the desired derivatives from those of the programs’s basic operations. Thus, automatic differentiation is at the intersection of calculus and programming. However, the programs of interest are more than chains of operations: they may include control-flow constructs, data structures, and computational effects (e.g., side-effects or exceptions). Calculus does not provide an immediate justification for the treatment of such programming-language features.
In the present work we help bridge the gap between rules for automatic differentiation in expressive programming languages and their mathematical justification in terms of denotational semantics. Specifically, we consider automatic differentiation from a programming-language perspective by defining and studying a small but powerful language. The language is a functional first-order language, with only rudimentary data structures, but with conditionals and recursively defined functions (from which loops can be constructed). Additionally, it contains a construct for reverse-mode differentiation, explained in detail below. Our language is thus inspired by modern systems for machine learning, which include standard programming constructs and support reverse-mode differentiation. Reverse-mode differentiation permits the computation of gradients, forward-mode derivatives, and more. Indeed as our differentiation construct is a language primitive, differentiations can be nested within differentiations, allowing the computation of higher-order derivatives.
In the setting of a language such as ours, we can consider some common approaches to implementing differentiation:
• One approach relies on code transformation, whether on source code or intermediate representations. For example, for the derivative of a conditional expression
• Another approach relies on tracing, typically eliminating control structures to produce a simpler form of code, which we call an execution trace, that can more easily be differentiated. For example, to produce the derivative of
This approach thereby conveniently avoids the problem of defining code transformations for conditionals and many other language constructs. It can also be implemented efficiently, sometimes in part with JIT compilation. For these reasons, trace-based differentiation is of growing importance. It is employed, for instance, in Autograd (Maclaurin et al., 2015), TensorFlow Eager Mode (Shankar and Dobson, 2017), Chainer (Tokui, 2018), PyTorch (PyTorch, 2018), and JAX (Frostig et al., 2018).
We therefore focus on trace-based differentiation in this paper, and give an operational semantics for our language using the trace-based approach. To do so, we define a sublanguage of execution trace terms (called simply trace terms below). These terms have no conditionals, function definitions or calls, or reverse-mode differentiations. They do have local definitions, corresponding to fanout in the graphs, but are not necessarily in A-normal form. Tracing is modeled by a new kind of evaluation, called symbolic evaluation. This uses an environment for the free variables of a term to remove conditionals and function calls. Function derivatives at a given value are evaluated in three stages: first, the function is traced at that value; next, the resulting trace term is symbolically differentiated (largely just using the chain rule), resulting in another such trace term; and, finally, that term is evaluated.
We do not account for some of the optimizations used in practice. Doing so would have been a more complicated enterprise, possibly with more arbitrary choices tied to implementation details, and we wished to get a more straightforward formalization working first.
From a mathematical perspective, both approaches to implementing differentiation pose correctness problems. In particular, functions defined using conditionals need not be continuous, let alone differentiable. Consider, for example, the following definition
f(x:real):real=if(x<0)then0elsex
of the popular ReLU function (Goodfellow et al., 2016). This function is not differentiable at . Further, changing the function body to
g(x:real):real=if(x=0)then0elsex
The derivative of this function at is . However, differentiation “by branches” (whether by code transformation or tracing) would produce the wrong answer, .
In order to capture the mathematical perspective, in addition to its operational semantics we give our language a denotational semantics. This semantics is based on classical notions of differentiation from real analysis (see, for example, (Trench, 2003)). That theory concerns multivariate functions on the reals defined on open domains, i.e., partial such functions with open domains of definition. In our semantics, we make use of those that are smooth (that is, those that can be partially differentiated any number of times). A particularly pleasing aspect of this mathematical development is how well domain theory (needed to account for recursion) interacts with differentiation.
Partiality is necessary, as for any language with general recursion, but it also gives us useful flexibility in connection with differentiation. For example, let be the approximation to which is equal to it except on the diagonal (i.e., where both arguments are equal) where it is undefined. Then
˙f(x:real):real=if(x˙<0)then0elsex
defines an approximation to ReLU which is undefined at . The approximation to is (unlike ) continuous (i.e., the pre-images of and are open sets), and the approximation to ReLU is differentiable wherever it is defined. Therefore, we design the semantics of our language so that it forbids functions such as but allows related approximations such as . An interesting question is how satisfactory an idealization this is of programming practice (which in any case works with approximate reals). We return to this point in the final section.
Proceeding in this way, we obtain adequacy theorems (i.e., operational soundness and completeness theorems) connecting the operational semantics of our language with a denotational semantics based on the classical theory of differentiation of partially defined multivariate real functions. Our theorems apply not only to conditional expressions but to the full language.
In sum, the main contributions of this paper are: (1) a first-order language with conditionals, recursive function definitions, and a reverse-mode differentiation construct; (2) an operational semantics that models one form of trace-based differentiation; (3) a denotational semantics based on standard mathematical notions from real analysis and domain theory; and (4) theorems that show that the two semantics coincide, i.e., the derivatives computed by the operational semantics are indeed the correct derivatives in a mathematical sense. Beyond the specifics of these results, this paper aims to give some evidence of the relevance of ideas and techniques from the programming-languages literature for programming systems that include automatic differentiation, such as current systems for machine learning.
While traditionally associated with scientific computing, automatic differentiation is now a central component of many modern machine learning systems, and those for deep learning in particular (Goodfellow et al., 2016). These systems often employ automatic differentiation to compute the gradients of “loss functions” with respect to parameters, such as neural network weights. Loss functions measure the error resulting from particular values for the parameters. For example, when a machine-learning model is trained with a dataset consisting of pairs , aiming to learn a function that maps the ’s to the ’s, the loss function may be the distance between the ’s and the values the model predicts when presented with the ’s. By applying gradient descent to adjust the parameters, this error can be reduced, until convergence or (more commonly) until the error is tolerable enough. This simple approach has proven remarkably effective: it is at the core of many recent successes of machine learning in a variety of domains.
Whereas gradients are for functions of type , for , treating the more general functions of type , for , works better with function composition, and with the composite structures such as tensors of reals used in deep learning. The literature contains two basic “modes” for differentiating such functions. Forward-mode extends the computation of the function, step by step, with the computation of derivatives; it can be seen as evaluating the function on dual numbers of the form where is nilpotent. In contrast, reverse-mode propagates derivatives backwards from each output, typically after the computation of the function. Reverse-mode differentiation is often preferred because of its superior efficiency for functions of type with . In particular, systems for machine learning, which often deal with loss functions for which , generally rely on reverse-mode differentiation. We refer the reader to the useful recent survey (Baydin et al., 2018) for additional background on these two modes of differentiation; it also discusses the use of higher-order differentiation.
Applications to machine learning are our main motivation. Accordingly, our language is loosely inspired by systems for machine learning, and the implementation strategies that we consider are ones of current interest there. We also de-emphasize some concerns (e.g., numerical stability) that, at present, seem to play a larger role in scientific computing than in machine learning. As noted in (Baydin et al., 2016), the machine learning community has developed a mindset and a body of techniques distinct from those traditional in automatic differentiation.
The literature on scientific computing has addressed the correctness problem for conditionals (Beck and Fischer, 1994; Fischer, 2001), although not in the context of a formally defined programming language. In (Mayero, 2002) a formal proof of correctness was given in Coq (Bertot and Castéran, 2013) for an algorithm for the automatic differentiation of straight-line sequences of Fortran assignments. Closer to machine learning, (Selsam et al., 2017) consider a stochastic graphical formalism where the nodes are random variables, and use the Lean theorem prover (de Moura et al., 2015) to establish the correctness of stochastic backpropagation. However, overall, the literature does not seem to contain semantics and theorems for a language of the kind we consider here.
Our work is also related to important papers by by Ehrhard, Regnier, et al., and by Di Gianantonio and Edalat. Ehrhard and Regnier introduce the differential -calculus (see (Ehrhard and Regnier, 2003)); this is a simply-typed higher-order -calculus with a forward-mode differentiation construct which can be applied to functions of any type. As described in (Blute et al., 2010), the differential -calculus can be modeled using the category of convenient vector spaces and smooth functions between them (see (Kriegl and Michor, 1997)). They do not give an operational semantics but they do give rules for symbolic differentiation and it should not be too difficult to use them to give an operational semantics. However their language with its convenient vector space semantics only supports total functions. It therefore cannot be extended to include recursive function definitions or conditionals (even with total predicates, as continuous functions from to the booleans are constant). Di Gianantonio and Edalat (Di Gianantonio and Edalat, 2013) prove adequacy theorems for their language, as do we, but their work differs from ours in several respects. In particular, their language has first-order forward-mode but no reverse-mode differentiation: our language effectively supports both, and at all orders. On the other hand, their language allows recursively-defined higher-order functions and accommodates functions, such as the ReLU function, which are differentiable in only a weaker sense. As far as we know, no other work on differentiable programming languages (e.g., (Pearlmutter and Siskind, 2008; Elliott, 2018; Wang et al., 2018; Shaikhha et al., 2018; Manzyuk, 2012)) gives operational and denotational semantics and proves adequacy theorems. Further afield, there is a good deal of work in the categorical literature on categories equipped with differential structure, for example (Blute et al., 2009; Bucciarelli et al., 2010).
Outline
Section 2 defines our language. Section 3 gives it an operational semantics with rules for symbolically evaluating general terms to trace terms, and for symbolically differentiating these terms. Sections 4 and 5 cover the needed mathematical material and the denotational semantics. Sections 6 establishes the correspondence between operational and denotational semantics. Section 7 concludes with discussion and some suggestions for future work.
2. A simple language
The types of our language are given by the grammar:
T::=real∣unit∣T×U
We will make use of iterated products , defined to be when , when , and, recursively, , when ; we write for the -fold iterated product of . Note that this type system includes the types of tensors (multidimensional arrays) of a given shape: the type of tensors of shape is the iterated product . The terms and boolean terms of the language are built from operation symbols and predicate symbols . An example operation symbol could be for dot product of vectors of dimension (for ); an example predicate symbol could be .
The terms are given by the following grammar, where and range over disjoint countably infinite sets of ordinary and function variables, respectively (so we have disjoint alphabets of ordinary and function variables):
M::=x∣r(r∈R)∣M+N∣op(M)∣letx:T=MinN∣∗∣⟨M,N⟩T,U∣fstT,U(M)∣sndT,U(M)∣ifBthenMelseN∣letrecf(x:T):U=MinN∣f(M)∣M.rdL(x:T.N)\parB::=pred(M)∣true∣false
These constructs are all fairly standard, except for , which is for reverse-mode differentiation, and which we explain below. We treat addition separately from the operations to underline the fact that the commutative monoid it forms, together with zero, is basic for differentiation. For example, the rules for symbolic differentiation given below make essential use of this structure, but do not need more any more of the available vector space structure.
Note the type subscripts on pairing and projection terms. Below, we rely on these subscripts for symbolic differentiation. In practice they could, if needed, be added when type-checking.
The sets and of free ordinary variables and free function variables of a term are understood as usual (and similarly for boolean terms). As is also usual, we do not distinguish -equivalent terms (or boolean terms).
The useful abbreviation
let⟨x0:T0,…,xn−1:Tn−1⟩=MinN
provides an elimination construct for iterated products. When this is
letx:unit=MinN
where ; when it is the above let construct; otherwise, it is defined recursively by:
let⟨x0:T0,…,xn:Tn⟩=MinN=letz:(T0×…×Tn)=Minlet⟨x0:T0,…,xn−1:Tn−1⟩=fstT0×…×Tn−1,Tn(z)inletxn:Tn=sndT0×…×Tn−1,Tn(z)inN
(where is chosen not free in ).
We have zero and addition only at type . At other types we proceed inductively:
0real=00unit=∗0T×U=⟨0T,0U⟩
and:
Skating over the difference between terms and their denotations, is the reverse-mode derivative at , evaluated at , of the function , where . Reverse-mode differentiation includes gradients as a special case. When and , the gradient of at is given by:
For definitions of gradients, Jacobians, and derivatives see Section 4.1 below, particularly equations (1), (2), (3), and (4). More generally, for an introduction to real analysis including vector-valued functions of several variables and their differentials and Jacobians, see, for example, (Trench, 2003).
As in (Christianson, 2012), and as validated by equation (6) below, forward-mode differentiation can be defined using nested reverse-mode differentiation. We can set:
So our language effectively also has forward-mode differentiation.
Function definitions can be recursive. Indeed a function can even be defined in terms of its own derivative: in a recursive function definition
Turning to typing, operation and predicate symbols have assumed arities, written and ; we write for the set of operation symbols of arity . As examples, we would have and . Figure 1 gives typing rules for sequents of the forms
Φ∣Γ⊢M:TΦ∣Γ⊢B
where (type) environments have the form
x0:T0,…,xn−1:Tn−1
( all different) and where function (type) environments have the form
f0:T0→U0,…,fn−1:Tn−1→Un−1
( all different). We adopt the usual overwriting notations and for type environments.
The typing rule for function definitions forbids any global variable occurrences (i.e., free variables in function definitions). This restriction involves no loss in expressiveness: as in lambda lifting, one can just add any global variables to a function’s parameters, and then apply the function to the global variables wherever it is called. The restriction enabled us to prove part (2) of Theorem 6.2 (below), but we conjecture it is not needed.
Our various abbreviations have natural admissible typing rules:
Φ∣Γ⊢M:T0×…,×Tn−1Φ∣Γ[x0:T0,…,xn−1:Tn−1]⊢N:UΦ∣Γ⊢let⟨x0:T0,…,xn−1:Tn−1⟩=MinN:U
Φ∣Γ[x:T]⊢N:UΦ∣Γ⊢L:TΦ∣Γ⊢M:TΦ∣Γ⊢M.fdU,L(x:T.N):U
Φ∣Γ⊢0T:TΦ∣Γ⊢M:TΦ∣Γ⊢N:TΦ∣Γ⊢M+TN:T
We may write (or ) instead of if has no free ordinary (or function) variables (and similarly for boolean terms). Typing is unique: for any , , and there is at most one type such that holds.
As an example, we use our language to program a miniature version of an algorithm for training a machine learning model by gradient descent, loosely based on (Goodfellow et al., 2016, Algorithm 8.1). In such training, one often starts with an untrained model, which is a function from inputs (for example, images) and parameter values to output “predictions” (for example, image labels). Relying on a dataset of input/output pairs, one then picks values of the parameters by gradient descent, as indicated in the Introduction. In our miniature version, we treat inputs, parameter values, and outputs as reals, and we assume that the training data consists of only one fixed input/output pair . We also assume that we have real constants (for the initial value for gradient descent), (for the learning rate, which is fixed) and (for the desired maximum loss on the dataset), and the infix predicate symbol . We can then define the trained model from the untrained model and a loss function as follows:
The example above is typical of what can be expressed in our language, and many variants of machine learning techniques that rely on gradient descent (e.g., of the kind presented in (Goodfellow et al., 2016), and commonly used in systems like TensorFlow) are in scope as well. For instance, there is no difficulty in expressing optimization with momentum, or differentially private stochastic gradient descent (e.g., (Song et al., 2013; Abadi et al., 2016b)). Probabilistic choice may be treated via random number generators, as is done in practice. Architectures that rely on convolutions or RNN cells can be expressed, even conveniently, with a suitable choice of primitives.
3. Operational semantics
We give a big-step operational semantics, specified with Felleisen and Friedman’s method (Felleisen and Friedman, 1987) using evaluation contexts and redexes. Other styles of operational semantics accommodating differentiation are surely also possible.
Terms and boolean terms are (ordinarily) evaluated to closed values and (necessarily) closed boolean values. The most original aspect of our operational semantics concerns the evaluation of differential terms; this is based on the trace-based approach outlined in the Introduction, and uses a second mode of evaluation: symbolic evaluation.
The core idea is that to evaluate a differential term
M.rdL(x:T.N)
one first evaluates and , and then performs differentiation before evaluating further. There are two differentiation stages. First, using the closed value of for the differentiation variable , is symbolically evaluated to a trace term , thereby removing all control constructs from , but possibly keeping the variable free in , as the derivative may well depend on it. For example, when is
However, this idea is not enough by itself as the differential term may occur inside yet another differential term. One therefore also needs to be able to symbolically evaluate the differential term. That is done much as in the case of ordinary evaluation, but now symbolically evaluating redexes in and until one is left with the problem of symbolically evaluating a term of the form
W.rdV(x:T.N)
where and are values that may contain free variables. One then proceeds as above, symbolically evaluating (now using the closed value of ) and then performing symbolic differentiation. As there is some duplication between these two symbolic and ordinary evaluation processes, our rule for ordinarily evaluating a differential term is designed, when executed, to first symbolically evaluate the term, and then ordinarily evaluate the resulting trace term.
The need to keep track of differentiation variables and their values for symbolic evaluation leads us to use value environments for ordinary variables. It is convenient to also use them for ordinary evaluation and to use function environments for function variables for both modes of evaluation.
Values are terms given by the grammar:
V::=x∣r(r∈R)∣∗∣⟨V,W⟩T,U
Note that, as indicated above, values may have free variables for the purposes of differentiation. Boolean values are boolean terms given by:
Vbool::=true∣false
Closed values have unique types ; the set of closed values of type is ; and the set of boolean values is . We assume available operation and predicate symbol evaluation functions
ev:OpT,U×ValT⇀ValUbev:PredT×ValT⇀Valbool
We also assume that for every operator of arity there is an operator of arity . The idea is that is the reverse-mode derivative of at evaluated at . We write for . For example, for we would have:
ev(DProd2,⟨⟨a,b⟩,⟨a′,b′⟩⟩)=aa′+bb′
and
ev((DProd2)r,⟨⟨⟨a,b⟩,⟨a′,b′⟩⟩,c⟩)=⟨⟨ca′,cb′⟩,⟨ca,cb⟩⟩
We next define (value) environments , function environments , and (recursive function) closures , the last two mutually recursively:
• Value environments are finite functions
ρ={x0↦V0,…,xn−1↦Vn−1}
from ordinary variables to closed values.
• Every finite function
φ={f0↦Cl0,…,fn−1↦Cln−1}
from function variables to closures is a function environment.
• If and then is a closure, written .
For any and with , is the closed value obtained by substituting for all free occurrences of in .
Trace terms , are defined as follows:
C::=x∣r(r∈R)∣C+D∣op(C)∣letx:T=CinD∣∗∣⟨C,D⟩T,U∣fstT,U(C)∣sndT,U(C)
They are the terms with no conditionals, function definitions or applications, or differentiations.
We will define two ordinary evaluation relations, and one symbolic one:
• For all and we define evaluation relations between terms and closed values and between boolean terms and closed boolean values via rules establishing sequents of the forms:
φ∣ρ⊢M⇒Vφ∣ρ⊢B⇒Vbool
• For all and we define a symbolic evaluation relation between terms and trace terms via rules establishing sequents of the form:
φ∣ρ⊢M⇝C
Evaluation contexts (boolean evaluation contexts), ranged over by (resp. ), are terms with a unique hole :
E::=[]∣E+N∣V+E∣op(E)∣\parletx:T=EinN∣⟨E,N⟩T,U∣⟨V,E⟩T,U∣fstT,U(E)∣sndT,U(E)∣ifEboolthenMelseN∣f(E)∣M.rdE(x:T.N)∣E.rdV(x:T.N)\parEbool::=pred(E)
We write for the term obtained by replacing the hole in by the term and similarly; a context is trivial if it is ; and and are extended to contexts. We have and and similarly for boolean contexts.
Redexes, ranged over by , and boolean redexes, ranged over by , are given by:
R::=V+W∣op(V)∣\parletx:T=VinN∣fstT,U(V)∣sndT,U(V)∣ifVboolthenMelseN∣letrecf(x:T):U=MinN∣f(V)∣W.rdV(x:T.N)Rbool::=pred(V)
Note that boolean expressions are useful here in that they enable separate conditional and predicate redexes, and so evaluating predicates and making choices are distinct in the operational semantics.
The next lemma is the basis of a division into cases that supports operational semantics using evaluation contexts in the style of Felleisen and Friedman.
Lemma 3.1 (Evaluation context analysis).
1. Every term , other than a value, has exactly one of the following two forms:
• for a unique evaluation context and redex, or
• for a unique, and non-trivial, evaluation context and boolean redex.
2. Every boolean term , other than a boolean value, has exactly one of the following two forms:
• for a unique, and non-trivial, boolean evaluation context and redex, or
• for a unique boolean evaluation context and boolean redex.
The next lemma is useful to track types when proving theorems about the operational semantics.
Lemma 3.2 (Evaluation context polymorphism).
Suppose that . Then, for some type we have and, whenever , we have .
Analogous results hold for typings of any of the forms or or .
By the uniqueness of types, the types whose existence is claimed in the above lemma are unique.
The rules for ordinary evaluation are given in Figures 2 and 3; those for symbolic evaluation are given in Figures 4 and 5. The definitions are mutually recursive. They make use of the symbolic differentiation of trace terms: given a trace term , and values and (not necessarily closed), we define a trace term
W.RV(x:T.C)
intended to denote the reverse-mode derivative of the function , at , evaluated at . A definition is given in Figure 6; in the definition we assume that , and, as is common, that all binding variables are different.
Proposition 3.3 ().
The following typing rule is admissible:
Γ[x:T]⊢C:UΓ⊢V:TΓ⊢W:UΓ⊢W.RV(x:T.C):T
In large part because of the restrictions on trace terms, their symbolic differentiation is just a systematic, formal application of the chain rule. In our setting, this application requires a fair amount of attention to detail, for instance the use of the type decorations when giving derivatives of pairing and projection terms.
The reader may wish to try the following two evaluation examples with nested differentiation:
1.rd1(x:real.x×1.rd1(y:real.x+y))⇒1
and
letrecf(x:real):real=1.rd1(y:real.x+y)in1.rd1(x:real.x+f(x))⇒1
Examples of this kind can be used to illustrate perturbation confusion in forward differentiation, e.g., (Siskind and Pearlmutter, 2005, 2008).
We need some basic results on our evaluation relations. Two are standard: determinacy and type safety, and are used implicitly throughout the rest of the paper. The third connects symbolic and ordinary evaluation: one can interpolate symbolic evaluation within ordinary evaluation. It is principally helpful to reduce the completeness part of symbolic evaluation to the completeness of ordinary evaluation (see Theorem 6.7).
Proposition 3.4 (Determinacy of evaluation).
The following hold:
1. For any , , and , there is at most one value s.t. .
2. For any , , and , there is at most one trace term s.t. .
The following interpolation proposition establishes a certain consistency between the ordinary and symbolic evaluation relations.
Proposition 3.5 (Operational interpolation).
For all , , and closed values , the following are equivalent:
• ,
• and , for some .
For a type safety theorem, we need typing judgments , , and for environments, function environments, and closures (implicitly extending the notion of type). These are defined inductively by the following rules:
⊢Vi:Ti(i=0,n−1)⊢{…,xi↦Vi,…}:…,xi:Ti,…
⊢Cli:Ti→Ui(i=0,n−1)⊢{…,fi↦Cli,…}:…,fi:Ti→Ui,…
⊢φ:ΦΦ[T→U/f],x:T⊢M:U⊢cloφ(f(x:T):U.M):T→U
Unique typing extends to environments, to function environments, and to closures (indeed, a closure can only have type ).
Proposition 3.6 (Type safety).
Suppose
φ∣ρ⊢M⇒V⟹⊢V:T
and
φ∣ρ⊢M⇝C⟹Γ⊢C:T
4. Mathematical preliminaries
We now turn to the mathematical facts needed for the denotational semantics of our language. These concern the two modes of differentiation and their interaction with domain theory. We follow (Abramsky and Jung, 1994) for domain theory, but write dcppo for pointed dcpo, and say a partial order is coherent iff every compatible subset has a lub. (A subset is compatible if any two of its elements have an upper bound.) Every coherent partial order is a dcppo.
The collection of partial functions with open domain between two topological spaces forms a partial order under graph inclusion:
f≤g⟺f⊆g
equivalently, using the Kleene order 222We write for two mathematical expressions and to mean that if is defined so is , and they are then equal.: | {"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.9082496762275696, "perplexity": 1080.1268987541962}, "config": {"markdown_headings": false, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.3, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2021-10/segments/1614178361849.27/warc/CC-MAIN-20210301030155-20210301060155-00524.warc.gz"} |