text large_stringlengths 148 17k | id large_stringlengths 47 47 | score float64 2.69 5.31 | tokens int64 36 7.79k | format large_stringclasses 13 values | topic large_stringclasses 2 values | fr_ease float64 20 157 |
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Data reported by the weather station: 107630 (EDDN)
Latitude: 49.5 | Longitude: 11.08 | Altitude: 318
|Main||Year 1968 climate||Select a month|
To calculate annual averages, we analyzed data of 366 days (100% of year).
If in the average or annual total of some data is missing information of 10 or more days, this is not displayed.
The total rainfall value 0 (zero) may indicate that there has been no such measurement and / or the weather station does not broadcast.
|Annual average temperature:||8.5°C||366|
|Annual average maximum temperature:||13.0°C||365|
|Annual average minimum temperature:||4.2°C||364|
|Annual average humidity:||77.6%||362|
|Annual total precipitation:||-||-|
|Annual average visibility:||13.8 Km||366|
|Annual average wind speed:||9.2 km/h||366|
Number of days with extraordinary phenomena.
|Total days with rain:||221|
|Total days with snow:||55|
|Total days with thunderstorm:||45|
|Total days with fog:||254|
|Total days with tornado or funnel cloud:||0|
|Total days with hail:||3|
Days of extreme historical values in 1968
The highest temperature recorded was 31.1°C on July 1.
The lowest temperature recorded was -22.8°C on January 13.
The maximum wind speed recorded was 51.9 km/h on January 6. | <urn:uuid:2ed29869-20aa-4d27-a744-c824a3b48e1b> | 2.8125 | 354 | Structured Data | Science & Tech. | 69.704762 |
Re-topology, or sometimes just retopology, is the process of adjusting the topology of an existing 3D model. Topology refers to mesh-based 3D models, and is the way the individual polygons are meshed together into a 3d grid, with each polygon sharing a dividing line with each of it?s neighbours, until the mesh encloses a hollow 3D shape.
Below, we offer a selection of links from our resource databases which may match this term.
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By merging the traditionally distinct fields of topology and geometry, through the discovery of a new type of mathematics called persistent homology, math researchers have created a set of equations which simply describe the pattern and placement of complex fractals as part of a polygonal model - such as the unique froth on a wave, within the reach of real-time rendering
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BBC weather forcasting is about to get a makeover in the style of VR gameworlds. Weatherscape XT, a 3D meterological software suite developed by New Zealand firm Metra, and with help from the BBC itself, is set to give a realistic-looking,...
nternet, networks of connections between Hollywood actors, etc, are examples of complex networks, whose properties have been intensively studied in recent times. The small-world property (that everyone has a few-step connection to celebriti...
The freely available global mapping software proliferating the Internet ? Google Earth in the main ? is being eagerly adopted by researchers from a variety of fields as the most effective way to compare geographic data.
Researchers are edging toward the creation of new optical technologies using "nanostructured metamaterials" capable of ultra-efficient transmission of light, with potential applications including advanced solar cells and quantum computing...
Combining hospital MRIs with the mathematical tool known as network analysis, a group of researchers at UC San Francisco and UC Berkeley have mapped the three-dimensional global connections within the brains of seven adults who have genetic... | <urn:uuid:236148de-6181-482f-9d0f-b5fc706f88a3> | 2.96875 | 453 | Content Listing | Science & Tech. | 34.042636 |
Grass. Scientists have imitated natural photosynthesis and created a record-fast molecular catalyzer. (Credit: © Nejron Photo / Fotolia)
Artificial Photosynthesis Breakthrough: Fast Molecular Catalyzer -- Science Daily
ScienceDaily (Apr. 12, 2012) — Researchers from the Department of Chemistry at the Royal Institute of Technology (KTH) in Stockholm, Sweden, have managed to construct a molecular catalyzer that can oxidize water to oxygen very rapidly. In fact, these KTH scientists are the first to reach speeds approximating those is nature's own photosynthesis. The research findings play a critical role for the future use of solar energy and other renewable energy sources.
Read more ....
My Comment: This has the potential of being big. | <urn:uuid:06198aa9-b3f7-43ec-bec2-b343f51124f4> | 3.03125 | 158 | Truncated | Science & Tech. | 28.452879 |
I recently blogged that you can now play Angry Birds in your web browser. This opens up all sorts of video analysis possibilities for physics lessons and assessment. Students can easily make their own videos or you can pre-record your own. Videos can be recorded using Jing, Screencast-O-Matic, or Camtasia Studio. Analysis can be done in Logger Pro or Tracker.
Here are some possible investigations to carry out (shared by Michael Magnuson on the WNYPTA email list):
1. Make a reasonable estimate for the size of an angry bird, and determine the value of g in Angry Bird World. Why would the game designer want to have g be different than 9.8 m/s²? Download Angry Birds video.
2. Does the blue angry bird conserve momentum during its split into three? Download Red and Blue Birds video.
3. Does the white bird conserve momentum when it drops its bomb? Why would the game designer want the white bird to drop its bomb the way that it does? Download White Bird video.
4. Describe in detail how the yellow bird changes velocity. You will need to analyze more than one flight path to answer this question. Download Yellow Birds video.
5. Shoot an angry bird so that it bounces off one of the blocks. Determine the coefficient of restitution and the mass of the angry bird. Download Red Birds and Falling Block video.
You can download each video using the links above or get them all here.
Other posts with ideas about how to use Angry Birds in physics class:
- Rhett Allain’s analysis of The Physics of Angry Birds.
- John Burk’s post Introducing projectile motion using Angry Birds
- Peter Kupfer’s post Angry Birds and Physics
How have you used (or will use) Angry Birds in the classroom?
UPDATE 12-28-2011: Our class has been featured on CUNY-TV’s “Science and U!” Jump to 10:25 in the video below: | <urn:uuid:cbae3902-5532-4ea9-b7b7-919234ad0234> | 3.296875 | 422 | Personal Blog | Science & Tech. | 70.689083 |
NASA has moved into extra-solar planetary weather forecasting. Well, mapping, but one has to start somewhere. Researchers using the agency's Spitzer infrared space telescope have mapped the weather patterns of two extremely hot, distant planets. The May 9th edition of Nature carries a description of the winds on the surface of …
Sounds like they found HELL
Well, if a hot, dark planet is out there as "Spicy" is described, I'd say this is a good candidate for the proverbial HELL we've all been told we're going to.
Now, if only they can find a cool, bright place with lots of harps...
Windy & Spicy
Sounds like a curry.
Well done on some creative renaming - it really worked! :)
SI Units please
Centigrade or kelvin are much better to use - I find it hard to understand a scale that is related to the temperature of a horse's anus.
It's NASA, not SI
NASA did the research, hence the ridiculous units.
They're not too good at converting between imperial and SI units... remember the mixup with the Mars satellite that put it in the planet?
Dumbing down much?
Thanks for clarifying that the light from Windy takes 60 years to reach us and that it's 60 light-years away. Could someone clarify for me how long it takes the light to get from Spicy at 279 light-years away?
- Geek's Guide to Britain INSIDE GCHQ: Welcome to Cheltenham's cottage industry
- 'Catastrophic failure' of 3D-printed gun in Oz Police test
- Game Theory Is the next-gen console war already One?
- BBC suspends CTO after it wastes £100m on doomed IT system
- Peak Facebook: British users lose their Liking for Zuck's ad empire | <urn:uuid:481c4c3d-0b46-48b3-b837-7a78f0423840> | 2.734375 | 384 | Comment Section | Science & Tech. | 62.984274 |
In 1985 Klaus von Klitzing won the Nobel Prize for discovery of the quantised Hall effect. The previous Nobel prize awarded in the area of semiconductor physics was to Bardeen, Shockley and Brattain for invention of the transistor. Everyone knows how important transistors are in all walks of life, but why is a quantised Hall effect significant?
100 years ago E.H. Hall discovered that when a magnetic field is applied
perpendicular to the direction of a current flowing through a metal a voltage
is developed in the third perpendicular direction. This is well understood
and is due to the charge carriers within the current being deflected towards
the edge of the sample by the magentic field. Equilibrium is achieved when
the magnetic force is balanced by the electrostatic force from the build
up of charge at the edge. This happens when Ey = vxBz
.The Hall coefficient is defined as RH =
and since the current density is jx = vxNq
, RH =1/Nq
in the case of a single species of charge carrier. RH can thus
be measured to find N the density of carriers in the material. Often
this transverse voltage is measured at fixed current and the Hall resistance
recorded. It can easily be seen that this Hall resistance increases linearly
with magnetic field.
In a two-dimensional metal or semiconductor the Hall effect is also observed, but at low temperatures a series of steps appear in the Hall resistance as a function of magnetic field instead of the monotonic increase. What is more, these steps occur at incredibly precise values of resistance which are the same no matter what sample is investigated. The resistance is quantised in units of h/e2 divided by an integer. This is the QUANTUM HALL EFFECT.
The figure shows the integer quantum Hall effect in a GaAs-GaAlAs heterojunction, recorded at 30mK. The QHE can be seen at liquid helium temperatures, but in the millikelvin regime the plateaux are much wider. Also included is the diagonal component of resistivity, which shows regions of zero resistance corresponding to each QHE plateau. In this figure the plateau index is, from top right, 1, 2, 3, 4, 6, 8.... Odd integers correspond to the Fermi energy being in a spin gap and even integers to an orbital LL gap. As the spin splitting is small compared to LL gaps, the odd integer plateaux are only seen at the highest magnetic fields. Important points to note are:
The zeros and plateaux in the two components of the resistivity tensor are intimately connected and both can be understood in terms of the Landau levels (LLs) formed in a magnetic field.
In the absence of magnetic field the density of states in 2D is constant as a function of energy, but in field the available states clump into Landau levels separated by the cyclotron energy, with regions of energy between the LLs where there are no allowed states. As the magnetic field is swept the LLs move relative to the Fermi energy.
When the Fermi energy lies in a gap between LLs electrons can not move to new states and so there is no scattering. Thus the transport is dissipationless and the resistance falls to zero.
The classical Hall resistance was just given by B/Ne. However, the number of current carrying states in each LL is eB/h, so when there are i LLs at energies below the Fermi energy completely filled with ieB/h electrons, the Hall resistance is h/ie2. At integer filling factor this is exactly the same as the classical case.
The difference in the QHE is that the Hall resistance can not change
from the quantised value for the whole time the Fermi energy is in a gap,
i.e between the fields (a) and (b) in the diagram, and so a plateau results.
Only when case (c) is reached, with the Fermi energy in the Landau level,
can the Hall voltage change and a finite value of resistance appear.
This picture has assumed a fixed Fermi energy, i.e fixed carrier density, and a changing magnetic field. The QHE can also be observed by fixing the magnetic field and varying the carrier density, for instance by sweeping a surface gate.
Although it might be thought that a perfect crystal would give the strongest effect, the QHE actually relies on the presence of dirt in the samples. The effect of dirt and disorder can best be though of as creating a background potential landscape, with hills and valleys, in which the electrons move. At low temperature each electron trajectory can be drawn as a contour in the landscape. Most of these contours encircle hills or valleys so do not transfer an electron from one side of the sample to another, they are localised states. A few states (just one at T=0) in the middle of each LL will be extented across the sample and carry the current. At higher temperatures the electrons have more energy so more states become delocalised and the width of extended states increases.
The gap in the density of states that gives rise to QHE plateaux is the gap between extended states. Thus at lower temperatures and in dirtier samples the plateaus are wider. In the highest mobility semiconductor heterojunctions the plateaux are much narrower.
In very high mobility samples extra plateaux appear between the regular quantum Hall plateaux, at resistances given by h/e2 divided by a rational fraction p/q instead of an integer. This is the fractional quantum Hall effect (FQHE). Early observations found that q was always an odd number and that certain fractions gave rise to much stronger features than others. The FQHE is much more difficult to explain since it originates from many electron correlations, but for this reason has been of great interst to theoreticians and experimentallists alike.
In some materials there are more than one species of charge carrier. These may be elecrons in different conduction band minima, different spatially confined subbands or electrons and holes simultaneously present. The numbers and mobilities of all the species have to be considered to find the transport coefficients.
If there are electrons and holes the total filling factor is the difference between the filling factors for electrons and holes. At certain fields this can be zero, at which point the Hall resistance itself becomes zero!
Last updated 05/02/97 by David R Leadley.
All rights reserved. Text and diagrams from this page may only be used for non-profit making academic excerises and then only when credited to D.R. Leadley, Warwick University 1997. | <urn:uuid:4d49f668-e836-42fe-946a-68e62fe1ff0a> | 3.5625 | 1,394 | Knowledge Article | Science & Tech. | 48.9762 |
Writes only the starting XML element to an XML document or stream.
This member is overloaded. For complete information about this member, including syntax, usage, and examples, click a name in the overload list.
|WriteStartObject(XmlDictionaryWriter, Object)||Writes the start of the object's data as an opening XML element using the specified XmlDictionaryWriter.|
|WriteStartObject(XmlWriter, Object)||Writes the start of the object's data as an opening XML element using the specified XmlWriter.|
The , WriteObjectContent, and WriteEndObject methods must be implemented. The three methods are used in succession to write the complete serialization using the pattern: write start, write content, and write end. If the implementation writes using XML elements, attributes can be inserted before writing the contents of the object. The three methods are also called by the virtual implementation of the WriteObject method. | <urn:uuid:d700dfa3-4dde-4642-bdc1-08b5c9c0c2ec> | 3.140625 | 196 | Documentation | Software Dev. | 31.006046 |
2.3.3 A Penguin Foraging Simulation Game
Display materials for this Activity and tell students that they will be simulating the foraging behavior of penguins. Have them review the Adelie fact sheet, and discuss items which seem most of interest to your class, setting the foraging simulation in its real-world context. Explain that the washers, toothpicks, M&Ms, and marbles represent penguin food items. Then demonstrate the use of the clothespin to represent a penguin's bill! The object of the game is to capture as much "prey" (in the paper cup) as you can within a time limit. The goal is to accumulate 500 points, expending the least energy in the shortest period of time.Sidebar: Foraging Facts
Many factors contribute to the chick-raising and foraging success of penguins in Antarctica, including:
Adapted with permission from the Los Marineros Curriculum Guide, a marine science curriculum available from the Santa Barbara Museum of Natural History at 805-682-4711, ext. 311.
Use a globe to show that all 17 species of penguins live south of the equator. One species, the Galapagos penguin, lives on the equator in the path of the cold Peru Current. Seven kinds of penguins visit Antarctica, but only two species, the Adelie and Emperor penguins, breed exclusively on the Antarctic continent.
How are the adult Adelie penguins able to survive while sitting on the nest? (Blubber or body fat is a primary food source.)
Penguins are the only birds that migrate by swimming. Students can research and map their migration routes, up the west coast of South America to Tetal Point in northern Chile, or up to the east coast of South America past Argentina as far north as Rio de Janeiro in Brazil. Estimate the distances they travel. Using satellite images located on-line, students can match the migratory routes of penguins with the location of currents. What assumptions can they make about migration routes by looking at infrared imagery? (penguins follow cold water currents)
Research North America's own "penguins," the flightless Great Auks. Learn how Great Auks were similar to penguins. Find out why they were slaughtered (for food, their feathers, and for stuffed specimens). These birds became extinct in 1844 when two museum collectors landed on a remote island off Iceland, strangled the last surviving pair for their collection and then smashed the last egg.
Information on Flightless Birds, Behavior, Breeding, Locomotion, Colonies,
Adelies, Emperors, Gentoos, Chinstraps and Crested penguins
Sounds and sights from wildlife sound recordist and NSF Artist-in-Residence,
Doug Quin, including penguins, leopard and Weddell seals, and the sounds
The Adelie Penguin Monitoring Program of the Australian Antarctic Division
| From The Field | Video Information | Researcher Q
& A | | <urn:uuid:49aab467-ec31-4b5f-954c-fbb23a424cb2> | 4.1875 | 629 | Tutorial | Science & Tech. | 44.535538 |
Mar 22, 2010
Guest Blog - Electricity used when pulling weight
We don't typically post items related to science fairs (I get a lot of them - they're always enjoyable but most aren't related to NXT but just use an NXT robot to facilitate something else), but I thought this was an interesting project worth sharing, especially because it's using an NXT to obtain the results - I've posted Keizo's results in the accompanying image.
BTW - Keizo is in 4th grade.
Thanks for sending this in Keizo! - Jim
How Much Electricity Is Used When A Robot Pulls A Certain Weight
By Keizo M.
Hypothesis: I think that the robot will use twice as much electricity when the weight of the car is doubled.
Why I Chose This Project: Last year I got a LEGO Mindstorms NXT 2.0 for my birthday. I really enjoyed it, but while using it, I noticed that the batteries run out quickly. I decided to measure how much electricity would be used when a robot pulls a weight.
Materials: -Lego Mindstorms ® NXT 2.0 -Digital Voltmeter -6 Rechargeable Batteries -Weights
1) Make a robotic car out of Lego Mindstorms NXT 2.0
2) Program the car to go forward and backward for 10 minutes
3) Charge the batteries
4) Measure volts in batteries
5) Put batteries in the car
6) Put weight on the car
7) Run the program
8) After 10 minutes stop the car
9) Take out batteries, and collect data
10) Repeat step 3 through 7 with different weights
Conclusion: When weight was increased, more electricity was used but it didn’t double. For example, when I doubled the weight from 1 pound to 2 pounds there was only a 0.066-volt difference.
Discussion: There wasn’t a huge difference when I increased the weight. Next time, I should make the robot go for 30 minutes instead of 10 minutes or put a heavier weight
Posted by: James Floyd Kelly (Jim) at 7:26 AM | <urn:uuid:5342e887-c066-476e-ab35-241727f892d9> | 3.25 | 441 | Personal Blog | Science & Tech. | 65.792164 |
It would seem that a beast covered in fur would be opposed to the planet staying warm but I have to tell you guys, our fur ain’t made of Gore-Tex and Thinsulate – so I’m pretty stoked that a report out of London indicates that, like the Medieval Warm Period, our current climate situation is likely to be preventing a mini-Ice Age:
Without human carbon dioxide emissions the next ice age would be imminent, according to a Nature Geoscience study led by a UCL scientist.
In the paper, scientists led by Professor Chronis Tzedakis (UCL Geography) have been able to ‘fingerprint’ the timing of past ice age activations, or ‘glacial inceptions’ by identifying the onset of abrupt temperature changes in Greenland and Antarctica.
By applying this ‘fingerprint’ method to a nearly identical interglacial period with similar levels of summer solar radiation to our own current period, some 780 thousand years ago, the researchers have been able to determine that glacial inception would indeed be expected to occur sometime within the next 1500 years, a blink of an eye in the context of the Earth’s lifespan. But due to high CO2 levels, and associated radiative forcing of global temperatures, it is expected to be delayed.
In a related announcement, the sun is hot.
Not Kells hot but pretty hot nonetheless. | <urn:uuid:19ab1842-449a-47dd-b9e7-40b539f8313a> | 3.203125 | 291 | Personal Blog | Science & Tech. | 26.087515 |
European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.
read more: http://www.eso.org/public/news/eso1241/
2012 DA14 is an approximately 40 meter diameter asteroid that will take a close approach to Earth in early 2013. Contrary to some reports on the web, there is no danger of it hitting us during this encounter. This visualization shows the trajectory of the asteroid as computed by JPL’s HORIZONS
( #Astronomy )
Pretty picture: Enceladus, in lovely color
Feb. 6, 2012 | 13:38 PST | 21:38 UTC
Here’s an awesome picture to start off the week. The data came from Cassini’s flyby of Enceladus on January 31, 2011; it was part of Cassini’s January 2012 data release. Most of the visible globe is lit by yellowish light reflected first from Saturn; only a thin crescent receives sunlight. At bottom center, Enceladus’ south polar plumes erupt into space. They are back-lit by the Sun. As usual for awesome Cassini color photos posted here, this one was processed by Gordan Ugarkovic.
The Pillars of Creation no longer exist. In 2007, the astronomers announced that they were destroyed about 6,000 years ago by the shock wave from a supernova.Because of the limited speed of light, the shock wave’s approach to the pillars can currently be seen from Earth, but their actual destruction will not be visible for another millennium. | <urn:uuid:298a2fc1-af6f-4a36-9a41-284615b59f8b> | 3.703125 | 404 | Content Listing | Science & Tech. | 55.665917 |
Saturday 25 May
Honeycomb coral (Favites abdita)
What’s the World’s Favourite Species?Find out here.
Honeycomb coral fact file
- Find out more
- Print factsheet
Honeycomb coral description
Favites abdita is part of the Faviidae family, a common group of reef-building, ‘stony’ corals, characterised by a hard, calcareous skeleton, called a ‘corallite’. Favites abdita forms what are known as ‘massive’ colonies, meaning that the coral grows in a characteristic mound or dome shape which has roughly similar dimensions (typically close to a metre) in all directions (3). Favites abdita is usually pale brown, darker coloured in more turbid (cloudy) environments, with brown or green oral discs (the soft tissue between the mouth and the surrounding tentacles of the anemone-like polyp), and thick, rounded corallite walls (4).Top
Honeycomb coral biology
A honeycomb coral colony is composed of numerous individual polyps, which can reproduce asexually by a process called ‘budding’ (where each polyp divides itself into two or more daughter polyps). Favites abdita is also a hermaphrodite and can reproduce sexually by producing small, pink eggs and white sperm packets, which are released into the water during a short spawning period, usually around mid-November (4) (5) (6).
Like other reef-building corals, Favites abdita has many microscopic, photosynthetic algae, called zooxanthellae, living within the polyp tissues. The coral and the algae have a mutually beneficial relationship; the coral provides protection for the algae, which in return provide energy and nutrients for the coral through photosynthesis. Both Favites abdita and its zooxanthellae are very sensitive to changes in water temperature and acidity, and any increase in the water temperature greater than one or two degrees above the normal average can stress the coral and cause ‘bleaching’, a phenomenon in which the coral expels it zooxanthellae and turns white (4) (7).Top
Honeycomb coral rangeTop
Honeycomb coral habitat
Favites abdita is found in most reef environments, although it is most common on subtidal and rocky reefs, on reef slopes and in lagoons. It usually inhabits depths between 1 and 15 metres, although it does occur down to 40 metres on rubble substrate that separates different reefs (1).Top
Honeycomb coral statusTop
Honeycomb coral threats
The proportion of corals threatened with extinction has increased dramatically in recent decades, with current estimates suggesting that a third of all coral species have an ‘elevated risk’ of extinction (8). Detailed studies have found that around 20 percent of the world’s coral reefs have been already been destroyed, while at least 24 percent of remaining reefs face a high risk of collapse (9).
Threats to Favites abdita include damage caused by fisheries, pollution from agriculture and industry, human developments, recreation and tourism. Favites abdita is also targeted for the aquarium trade. Corals are particularly affected by the changing global climate, with rising sea temperatures, ocean acidification and mass coral bleaching events all contributing to significant declines in corals. In addition, these varying conditions have greatly increased the susceptibility of corals to disease, a factor which has recently emerged as a major cause of reef deterioration (1) (8) (9).Top
Honeycomb coral conservation
Favites abdita is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that all trade in the species should be carefully monitored. It is also known from several Marine Protected Areas. Further research into aspects of Favites abdita’s ecology, abundance, population trends, habitat status and taxonomy is required in order to find out more about how the species is likely to respond to the increasing number of threats throughout its range. The identification and establishment of new protected areas may prove crucial for the conservation of Favites abdita and many other corals, while further research into disease, pathogen and parasite management in corals is also needed (1).
Find out more
For further information on the conservation of coral reefs see:Top
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
- Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
- Containing free calcium carbonate, chalky.
- A group of organisms living together. Individuals in the group are not physiologically connected and may not be related, such as a colony of birds. Another meaning refers to organisms, such as bryozoans, which are composed of numerous genetically identical modules (also referred to as zooids or ‘individuals’), which are produced by budding and remain physiologically connected.
- Possessing both male and female sex organs.
- Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
- Typically sedentary soft-bodied component of cnidaria, a group of simple aquatic animals including the sea anemones, corals and jellyfish. A polyp comprises a trunk that is fixed at the base, and a mouth that is placed at the opposite end of the trunk and is surrounded by tentacles.
- The production or depositing of eggs in water.
IUCN Red List (September, 2010)
CITES (September, 2010)
Coral Hub (October, 2010)
- Veron, J.E.N. (2000) Corals of the World. Australian Institute of Marine Science, Townsville, Australia.
- Kojis, B.L. and Quinn, N.J. (1982) Reproductive ecology of two Faviid corals (Coelenterata: Scleractinia). Marine Ecology Progress Series, 8: 251-255.
- Richmond, R.H. and Hunter, C.L. (1990) Reproduction and recruitment of corals: comparisons among the Caribbean, the Tropical Pacific and the Red Sea. Marine Ecology Progress Series, 60: 185-203.
- Veron, J.E.N. (1993) Corals of Australia and the Indo-Pacific. University of Hawaii Press, Honolulu, Hawaii.
- Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321(5888): 560-563.
Miththapala, S. (2008) Coral Reefs. Coastal Ecosystem Series (Volume 1). Ecosystems and Livelihoods Group Asia, IUCN, Colombo, Sri Lanka. Available at:
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What is a black hole?
It is not really a hole, but a region in space with extremely strong gravity, so strong that not even light can escape. It is called black, because it gives off no light. It is impossible to observe or detect a black hole directly. Nobody has ever done this. But most astronomers believe they exist and continue to look for signs of indirect evidence that they exist. They do this by looking for the influence of black holes on other objects in space.
What is a comet?
It is an icy object found in our solar system, sometimes called a ‘dirty snowball’. As the comet passes near the Sun, the outer ice turns into gas and leaves a trail – the comet’s tail. The comet’s tail always points away from the Sun, even when it is moving away from the Sun. At those times the comet is flying tail first.
When is Halley’s comet due?
Halley’s comet is visible every 76 years. It was last seen in 1986. It will next be visible in 2061. | <urn:uuid:54a21c68-ad48-4c50-bfe1-56869bc7acdd> | 3.796875 | 226 | Knowledge Article | Science & Tech. | 73.180036 |
|Bialowieza primeval forest, Poland
The Bialowieza Forest (150 000 ha) is the last remaining fragment of primary deciduous and mixed forest in the European lowlands. It is the place where giant trees, not found anywhere else in Europe, exist. Many species which disappeared from other regions or are endangered are still present there, including large mammals (European bison, wolf and lynx) and rare species dependent on dead wood or large trees: woodpeckers, saproxylic coleopterans and fungi. Therefore, Bialowieza Forest is also a key refuge for relict, critically endangered species, because it is the only place where ecological and evolutionary processes, typical for the temperate forest biome, can still be observed.
Unfortunately, only 38% of the Polish part of Bialowieza Forest (the rest is located in Belarus) is currently protected as the national park and nature reserves. Despite of being a Natura 2000 site, most of the forest has undergone commercial logging and artificial reforestation also in the remaining natural stands. Forestry exploitation has been devastating pristine and unique habitats with the most precious flora and fauna species. Key ecological processes are being disrupted and unless the current unsustainable exploitation is stopped the few remaining fragments of natural old-growth forest will disappear in a matter of years. This loss of biodiversity will be irreparable.
Scientists warn that the protected part of the forest is too small to guarantee suitable conditions for most populations of endangered species and to safeguard natural processes in the long term. For instance, in the last two decades, the population of the White-backed Woodpecker has decreased by about 28% for the forest as a whole, but by 36% in stands managed commercially. This tremendous loss of biodiversity is a violation of the national law and it stands in opposition to the European nature conservation Directives. For decades, scientists and public opinion have demanded to stop timber harvesting except for small quotas covering the needs of local people.
OTOP (BirdLife Partner in Poland) recently entered administrative procedures aiming to change the forest management plan for the Bialowieza Forest and the related Natura 2000 management plan. OTOP is also involved in a proposal – now considered in the parliament – to change existing regulations, to enable easier extensions of existing and establishment of new national parks in Poland.
Wesołowski T. (2005): Virtual conservation: how the European Union is turning blind eye to its vanishing primaeval forests. Conservation Biology 19: 1349-1358.
OTOP, (BirdLife partner in Poland)
Dr Przemyslaw Chylarecki, pch(at)miiz.waw.pl | <urn:uuid:1c3fb4f3-73b9-4cdb-8171-0e0b4f5823c5> | 3.5625 | 557 | Knowledge Article | Science & Tech. | 24.116401 |
Solar timeSolar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. Apparent solar time is based on the apparent solar day, which is the interval between two successive returns of the sun to the local meridian. Solar time can be measured by a sundial.
The length of a solar day varies throughout the year. This is because the Earth's orbit is an ellipse, and not a circle, and the Earth moves faster when it is nearest the Sun and slower when it is farthest from the sun. (see Kepler's laws of planetary motion) Because of this, apparent solar days are shorter in March and September than they are in June or December. (The amount of daylight also varies because of the 23.5º tilt of the Earth's axis. (see Tropical year)
Mean solar time is based on a fictional mean sun which travels at a constant rate throughout the year. The length of a mean solar day is a constant 24 hours throughout the year although, as noted above, the amount of daylight varies.
The difference between apparent solar time and mean solar time, which is sometimes as great as 15 minutes, is called the equation of time. | <urn:uuid:d988863f-31ba-466a-a988-82750186cf62> | 4.34375 | 250 | Knowledge Article | Science & Tech. | 61.171295 |
"Invasive Plants are non-indigenous species or strains that become established in natural communities and wild areas, replacing native vegetation" (Invasive Plant Association of Wisconsin Web Site).
Why Should We Care about Invasive Plants?
Students, researchers, and the public come to the Lakeshore Nature Preserve to learn, study, and enjoy nature. Invasive non-native plant species threaten natural areas and restoration efforts. They invade natural areas, killing existing native plants and creating a simplified ecosystem that will not support a diverse set of native animals. They also invade restorations, preventing the establishment of native plants. Many of these invasive plants increase erosion by killing native ground level plants that normally hold soil.
Many invasive plants have become established in the Lakeshore Nature Preserve including:
Garlic Mustard, a ground layer plant, kills native woodland wildflowers by shading them.
Buckthorn and Honeysuckle, shrubs that form brushy thickets, shade out understory plants, create a good home for Garlic Mustard, and increase erosion.
Burdock, a plant with burs, catches human clothing and sometimes traps and kills bats and birds.
Canada Thistle, a particularly persistent and aggressive plant, invades open areas.
Recognize and Manage Invasive Plants
Many organizations have web sites to help people learn about invasive plants including:
Wisconsin Department of Natural Resources (DNR) Invasive Species: Plants - www.dnr.wi.gov/invasives/plants.htm
Invasive Plant Association of Wisconsin -www.ipaw.org
DNR Invasive Species of the Future - www.dnr.wi.gov/invasives/futureplants/
How You Can Help Control Invasive Plants
Volunteer to help remove invasive plants in the Preserve (see hints for Garlic Mustard below). Give money to help control invasive plants. Remove invasive plants in your own yard. Clean your shoes before you enter the Preserve so that you will not introduce seeds from other areas. Educate yourself about the emerging invasive plants and help control them in your neighborhood (see the last web site above).
Advantages of Controlling Invasive Plants
Controlling invasive non-native plant species in the Lakeshore Nature Preserve will help preserve natural plant and animal diversity and make the area more useful for research and environmental education. Controlling these plants will support efforts to establish native plants on the shorelines, decreasing erosion and stormwater runoff and improving Lake Mendota water quality. Controlling invasive plants will preserve the beauty of the Lakeshore Nature Preserve for future generations.
Garlic Mustard Control
When Garlic Mustard is pulled, be sure to get the root – broken off plants resprout and bloom later.
Bag and landfill all of your Garlic Mustard because second year plants will bloom and produce seeds even if they are pulled.
Volunteers pull Garlic Mustard frequently in the Preserve from mid-April thru mid-June. Contact Cathie Bruner (firstname.lastname@example.org or 265-9275) to participate. | <urn:uuid:2484279f-b174-4ec4-966a-b93e84afb60a> | 3.734375 | 656 | Knowledge Article | Science & Tech. | 29.730937 |
Optical Projection Tomography (OPT)
Optical Projection Tomography (OPT) is an optical imaging tool that creates high resolution 3D images of samples that are over ten times larger than samples imaged with other optical microscopic techniques (1). OPT images also have excellent contrast between a fluorescent region of interest and the rest of the specimen.
In OPT, a digital camera is used to capture an image of a transparent specimen. A specialized lens ensures that the image is formed only by the rays of light that are approximately parallel. This image is a projection through the specimen. A series of these projections obtained at various positions about the sample is used to create a 3-dimensional image of the sample. OPT is limited to transparent specimens as it is necessary to minimize light scattering through the sample. Mouse embryos are ideal specimens for OPT as they are naturally transparent.
One of the great strengths of OPT is the ability to acquire fluorescent images. This allows a researcher to tie fluorescent molecules to a particular type of molecule, such as a type of protein or gene. OPT can be used to map the distribution of the fluorescent molecules, which is also a map of the distribution of molecule under study.
At the Mouse Imaging Centre, we have begun research into altering the data processing methods in order to obtain higher resolution images of larger specimens. This will allow researchers to use OPT to study larger embryos and even complete organs.
Above Left: Three orthogonal planes out of an autofluorescence OPT
reconstruction of an E10.5 wildtype mouse embryo. The resolution of this
image is approximately 20 microns. Above Right: Surface rendering of
an E9.5 wildtype mouse embryo. Red: cardiac, white transparent: embryo.
Above: Surface renderings of the cardiac region of E12.5 wildtype
(left) and E12.5 Baf60c knockdown (right) mouse embryos. The outflow
tract of the wildtype heart undergoes constriction and septation,
whereas the outflow tract of the mutant has no constriction and little
septation. Red: myocardium, yellow: interior vessels of great
arteries. The myocardium is rendered transparently in the second set of
images to easily see the interior of the great vessels. This work is
described in "Baf60c is essential for function of BAF chromatin
remodelling complexes in heart development" by H. Lickert et. al.,
Nature Volume 432, Nov 4 2004. | <urn:uuid:ebb70018-f9d5-4b58-a58e-63702d693038> | 3.0625 | 523 | Knowledge Article | Science & Tech. | 38.59051 |
Code Listing 14: Query that demonstrates the LENGTH function
SQL> select first_name, LENGTH(first_name) length
2 from employee
3 order by length desc, first_name;
a query that uses the LENGTH function to
display the length of all FIRST_NAME values
from the EMPLOYEE table.
The online version of this article at bit.ly/
JAQPk3 includes examples of LENGTH and
other character functions in WHERE and
ORDER BY clauses.
8 rows selected.
SQL> select INSTR('Mississippi', 'issi',
2 from dual;
you with this task. Listing 12 shows a query
that uses the SUBSTR function to extract the
first three characters of every LAST_NAME
value from the EMPLOYEE table. The SUBSTR
function takes two required parameters
and one optional input parameter. The first
parameter is the literal or column value on
which you want the SUBS TR function to
operate. The second parameter is the position of the starting character for the substring, and the optional third parameter is
the number of characters to be included in
the substring. If the third parameter is not
specified, the SUBSTR function will return
the remainder of the string.
Listing 13 demonstrates the SUBS TR and
INS TR functions working together to display
the portion of every LAS T_NAME value from
the EMPLOYEE table that contains the “ton”
substring. In this example, the output from
the INS TR function provides the value for the
input parameter that specifies the position
for the SUBSTR function’s starting character.
In the LAST_NAME values in which the substring “ton” is not found, the entire LAS T_
NAME value is returned, for two reasons:
SUBSTR treats a starting position of 0 the
same as a starting position of 1 (that is, as the
first position in the string), and because the
query omits the optional length parameter,
the full remainder of the string is returned.
function takes as input the literal or column
value you want to search, followed by the
substring pattern to search for. In Listing 11,
the INS TR function finds the “ton” pattern in
only two column data values—both of them
Newton—and returns 4 as their position.
Because it did not find the search string in any
other values, the output for those values is 0.
Two additional parameters—starting
position and occurrence—are optional. The
starting position specifies the character in
the string from which to begin your search.
The default behavior is for the search to
begin at the first character—otherwise
known as character position 1. The occurrence parameter lets you specify which
occurrence of the substring you’d like to find.
For example, the word Mississippi includes
two occurrences of the “issi” substring. To
search for the starting-position location of
the second occurrence of this pattern, you
must provide the INSTR function with an
occurrence parameter of 2:
This article has shown you how character
functions can be used in SELECT statements
to manipulate the ways data is displayed.
You’ve seen how to convert data values to
uppercase, lowercase, and mixed cases and
how to search for strings within strings.
You’ve also seen how to pad and trim data
and how to specify a string’s total length.
By no means does this article provide an
exhaustive list of the Oracle character functions. Review the documentation for more
The next installment of SQL 101 will
discuss number functions and other miscellaneous functions.
Melanie Caffrey is
a senior development
manager at Oracle. She
is a coauthor of Expert
for Oracle Developers
and DBAs (Apress, 2011) and Expert Oracle
Practices: Oracle Database Administration from
the Oak Table (Apress, 2010).
INSTR('MISSISSIPPI','ISSI', 1, 2)
1 row selected.
EX TRACTING STRINGS FROM STRINGS
Sometimes you need to extract a portion of
a string for your desired output. The SUBS TR
(for substring) character function can assist
WHEN SIZE MAT TERS
Occasionally you need to determine a
string’s length—for example, to determine
the maximum number of characters a form
entry field should permit. Listing 14 shows
online-only article content
SQL 101, Parts 1–5
READ more about relational database
design and concepts
Oracle Database Concepts 11g
Release 2 ( 11. 2)
Oracle Database SQL Language Reference 11g
Release 2 ( 11. 2)
Oracle SQL Developer User’s Guide Release 3. 1
DOWNLOAD the sample script for | <urn:uuid:8348f91f-5885-444b-96c5-03a146fbd09e> | 3.140625 | 1,047 | Tutorial | Software Dev. | 50.289344 |
Before we begin, you should understand the basic PostgreSQL system architecture. Understanding how the parts of PostgreSQL interact will make the next chapter somewhat clearer. In database jargon, PostgreSQL uses a simple "process per-user" client/server model. A PostgreSQL session consists of the following cooperating Unix processes (programs):
A supervisory daemon process (the postmaster),
the user's frontend application (e.g., the psql program), and
one or more backend database servers (the postgres process itself).
A single postmaster manages a given collection of databases on a single host. Such a collection of databases is called a cluster (of databases). A frontend application that wishes to access a given database within a cluster makes calls to an interface library (e.g., libpq) that is linked into the application. The library sends user requests over the network to the postmaster (Figure 10-1(a)), which in turn starts a new backend server process (Figure 10-1(b))Figure 10-1(c)). From that point on, the frontend process and the backend server communicate without intervention by the postmaster. Hence, the postmaster is always running, waiting for connection requests, whereas frontend and backend processes come and go. The libpq library allows a single frontend to make multiple connections to backend processes. However, each backend process is a single-threaded process that can only execute one query at a time; so the communication over any one frontend-to-backend connection is single-threaded.
One implication of this architecture is that the postmaster and the backend always run on the same machine (the database server), while the frontend application may run anywhere. You should keep this in mind, because the files that can be accessed on a client machine may not be accessible (or may only be accessed using a different path name) on the database server machine.
You should also be aware that the postmaster and postgres servers run with the user ID of the PostgreSQL "superuser". Note that the PostgreSQL superuser does not have to be any particular user (e.g., a user named postgres), although many systems are installed that way. Furthermore, the PostgreSQL superuser should definitely not be the Unix superuser, root! It is safest if the PostgreSQL superuser is an ordinary, unprivileged user so far as the surrounding Unix system is concerned. In any case, all files relating to a database should belong to this Postgres superuser. | <urn:uuid:06489ac7-42d6-446a-ae22-14007cd3ac4a> | 3.09375 | 521 | Documentation | Software Dev. | 38.693788 |
A decomposition reaction is the opposite
of a synthesis reaction. In a decomposition reaction a reactant compound
is broken into two or more less complex substances. you are given a compound
as the reactant. In most cases, to find the product you split the compound
into the individual elements. The other types of decomposition reactions
(decomposition of a hydrate, chlorate, carbonate, etc.) are covered in other
tutorials. This tutorial focuses on the decomposition of a binary compound.
The general pattern of a decomposition reaction is:
AB --> A + B
Look at the example below.
--> 2H2(g) +
Water decomposes (usually
with the help of electricity) to form hydrogen gas and oxygen gas. Hydrogen
and oxygen are written with subscripts of 2 because they are both diatomic
let’s go step by step.
Predict the products when solid iron(II) oxide decomposes.
|1. Write the formula for the given reactant.
|2. On the products side of the equation, write
the symbols for the two elements in the compound. Be
sure to separate the elements by a + sign. If either of the elements
is diatomic, be sure to write a 2 as its subscript.
||FeO(s) --> Fe(s) +
Oxygen is diatomic, so it is written with a subscript
|3. Balance the equation.
||2FeO(s) --> 2Fe(s) | <urn:uuid:fdcf8142-8dd9-466b-a482-89bc054593db> | 4.375 | 324 | Tutorial | Science & Tech. | 53.844643 |
Senior Thesis: Engineering a Greener Future
By Mike Cariello ‘10 & Dusty Rybovich ‘10
It is our responsibility as engineers to design a better world. Liquified Natural Gas (LNG)-carrying behemoths belch greenhouse gases across the planet, while consuming the world’s limited supply of prized and precious oil. Traditional marine diesel propulsion is ultimately an inefficient generator of electrical power — and also creates harmful emissions. We have designed an alternate propulsion plant that uses fuel cells instead of engines, and makes excellent use of the boil-off gas that naturally occurs aboard LNG carriers.
Fuel cells have been studied for centuries, but their complex nature has discouraged in-depth research until recently. Our concept plant uses a type of fuel cell already being manufactured commercially in the United States; one that is fully capable of being used at sea with LNG fuel.
When compared to LNG carriers already in operation, our system can save at least $3,000,000 per year, per ship. This savings is mostly because our vessel can make a laden voyage using only the natural boil-off gas as fuel. It also produces only 44.7% of the CO2 output, 0.033% of the NOX output, and 0.002% of the SOX output of a modern LNG carrier.
Because the technology is so new, it is unlikely to be applied in the marine industry in the very near future. However, we hope that our research will help to clarify the advantages of this revolutionary technology, and push the industry into a new age of environmental consciousness. It is our wish that through our work the industry will be inspired to allocate more resources to developing this promising idea. | <urn:uuid:d47b2f09-bc63-4ac7-b9b1-4614a396a1c8> | 3.328125 | 354 | Academic Writing | Science & Tech. | 43.453 |
This pie chart shows the relative likelihood of observing particular other species commonly observed near Junco hyemalis
These species are those which most commonly occur in our observation database near Junco hyemalis. Observations favor some phyla over others. Typically Bacteria, Fungi, Protozoa, and Arthropods are more common in the field than in our records.
This species has a large range, with an estimated global Extent of Occurrence of 10,000,000 km². It has a large global population estimated to be 260,000,000 individuals (Rich et al. 2003). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.
Bahamas; Bermuda; Canada; Cayman Islands; Mexico; Puerto Rico; Saint Pierre and Miquelon; Turks and Caicos Islands; United States
Found in flocks in plowed fields, along roadsides, and at feeders.
List of Habitats:
1.9 Forest - Subtropical/Tropical Moist Montane
In sections below, we make some habitat inferences based on the known habitat preferences of those species most commonly associated with Junco hyemalis.
alpine, montane, temperate.
alpine meadows, boreal forest, broad-leaved forests, brush piles, brushy fence rows, canebrakes, coniferous forests, cultivated areas, deciduous woods and forests, desert, desert scrub, disturbed sites, evergreen forests, fence rows, fields, forest edges, forests, gardens, grasslands, hammocks, hardwood forests, mature forests, meadows, mediterranean-type shrubby vegetation, mesic forest, moist woods, montane forests, open forests, pasture, pine forests, rain forest, shrubby vegetation, small trees, subantarctic forest, subarctic forest, swamp forests, thickets, tropical forest, tundra grassland.
dry slopes, flood plains, hillsides, pastureland, roadsides, rock outcrops, rocky soils, sand dunes, streamsides, urban areas, valleys.
clay, limestone, loam, marl, sandy areas, sandy soil, thin soil.
along rivers, bays, bogs, brackish water, ditches, dry areas, estuaries, fens, flood plains, lagoon, lakes, marshes, mesic areas, pelagic, ponds, river banks, rivers, saltwater, shores, shrub dominated wetlands, stream banks, streams, subtidal muddy, swamps, swampy areas.
hillsides, ravines, rocky slopes. | <urn:uuid:5d874685-44d2-4acd-bc47-d62e0e617ff7> | 3.328125 | 594 | Structured Data | Science & Tech. | 27.865716 |
Solar Cycles Cause Global Warming & Cooling June 5, 2011Posted by honestclimate in Discussions.
Tags: climate change, global warming, solar cycles
Solar Cycles Cause Global Warming & Cooling
By Nick Anthony Fiorenza
ICECAP, June 3, 2011
Planetary warming has also been observed on Mars, Jupiter, Pluto, and on Neptune’s largest moon Triton during the decades following the peak of the “Solar Grand Maximum” – wonder why – there are no humans there! And Pluto is moving further from the sun in its orbit, thus it should be cooling, but instead it is warming. This is but one blatant indicator that suggests that the climate change on Earth is due to solar changes and our intersellar environment rather than mere human antics.
More importantly, the Sun is now changing from its Solar Grand Maximum to its Solar Grand Minimum. The Earth heats up after a Solar Grand Maximum, lagging a bit after the peak. With a Solar Grand Minimum now on its way, a “global cooling” may be on the horizon–a natural oscillation occurring in much longer solar cycles.
Latest science reveals that sharp increases in global warming “precede” sharp increases in CO2–not the other way around. Global warming causes more CO2 to be released form the oceans. Current research also shows that Earth’s oceans are now beginning to cool. It is also now clear that temperatures over the last century correlate far better with cycles in oceans than they do with carbon dioxide; and, the temperature cycles in oceans are caused by cycles of the sun.
Let the AGW (Anthropogenic Global Warming) advocates, as well as the media, continue to ignore all of this, perpetuating fear and advocating spending billions of dollars on non-solutions. Although humans contribute to greenhouse gases, the overall effect is a tiny fraction compared to natural causes. To say humans are the cause of global warming; and to also make predictions that global warming will continue to increase is simply inaccurate. This is not to ignore the silver lining of the global warming scare, as humanity must certainly learn to participate in harmony with nature, with the breath of the Earth and with her land and oceans; and with the cycles of the Sun, Moon, planets, and stars.
Read the rest here | <urn:uuid:55649d15-692c-415a-98fb-d2904aea2886> | 2.9375 | 483 | Personal Blog | Science & Tech. | 38.828645 |
Yes, it's the secondary effects that require energy.
A ship launched vertically must not only get the kinetic energy of final velocity, it must also balance against the pull of gravity (i.e. energy required to hover) during vertical ascent. It must also overcome air resistance.
An aircraft launch, ie. taking off horizontally, means that forward motion, requiring less initial energy, can create the lift to balance gravity. However, it runs longer, so basically what horizontal lift does is expend about the same amount of energy, but spread over a longer time with weaker engines; possibly more because you are fighting air resistance for a longer time while going horizontally. | <urn:uuid:cb8739e0-69bc-470f-8a3d-17c7e5e399da> | 2.796875 | 133 | Comment Section | Science & Tech. | 32.697821 |
[erlang-questions] Newbie question about line endings
Thu Dec 22 14:30:59 CET 2011
On Wed, Dec 21, 2011 at 8:21 PM, August Schwartzwald <
> I started to learn Erlang about a month ago. I really like it and think
> that with some more practice it will become a both unique and powerful tool
> in my growing box of programming languages. However, there is one thing
> about it that I find extremely annoying: The line endings.
> I currently know 5 programing languages, they have either 0 (python) or 1
> way to end lines (usually the ';' character). Erlang totally stands out
> here and requires that lines are ended in one of 4 different ways.
> Did some googling without finding any good reason to why the language
> works in this way. Can anyone here explain this?
There is no such ting as a "Line" in Erlang. Everything is a "form" so
there are no
line ending only form endings. A form is ended by a top-level "dot
Dot is a period "." white space is a blank,tab,newline or comment.
Comments start with "%" and are terminated by a newline
Top level means dot-whitespace is not contained inside a string, a quoted
atom or a comment.
The dot-whitespace convention came from Prolog, this is because Erlang was
first implemented in Prolog.
I don't really know why this convention was adopted in Prolog - but it might
have been done to simplify error handling. If you get a parse error in a
the parser wants to recover in some way. In Erlang/Prolog the strategy for
error recovery is extremely simple, if you get a parse error in a form the
parser just reports the error and goes to the next form - what constitutes
a form can be seen easily by only
looking at the stream of tokens generated by the tokeniser. This make
from parse errors very simple.
Dot-whitespace can be viewed as a synchronizing token for the purposes of
recovery during parsing of incorrect forms.
The easiest was to think of a form, is that it's like a sentence in English.
In your mail which posed this question, you ended most sentences with
dot whitespace (the exception was ? as a terminator), so Erlang forms are
like English sentences.
Just like in English semicolons are "long range" operators and separate
whereas commas separate short range constructs.
> erlang-questions mailing list
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More information about the erlang-questions | <urn:uuid:44b4da93-11bd-4bb7-a3e2-e7d6599d4e1f> | 2.765625 | 582 | Comment Section | Software Dev. | 56.130977 |
Well, did you read some books about progamming with C++ for Windows?
Did you try some simple sample applications like "Hello Worlds"?
Some others a little more complicated?
Note, that you cannot from the level "zero" jump to a level for programming serial port communications...
You really, really cannot pick this up as you go along without having a very good grounding in the basics of the c++ language, which is obvious you do not have. You need to start with the very basics and progress one step at a time. You are trying to undertake the triple jump without knowing how to run.
This says that ptr is a pointer to memory containing unsigned characters and that the characters pointed to cannot be changed. An area of memory containing unsigned characters is a character array (or an array of chars). So to use StuffData the first parameter has to be a pointer to an array of chars. So before you call the function StuffData, your program has to put into a char array the characters for StuffData. You cannot get away from not using a character array! This can be either a fixed size array (as in my previous example) or it can be a dynamically allocated memory (use new). However the character array is created, once it has been you need to populate it with the characters for StuffData.
So from your example, you want to use 11 characters. So you need a character array that contains these characters set up before you call StuffData.
The destination characters returned by StuffData in dst are NOT a c-style string and are NOT guaranteed to be NULL terminated. So using printf (or cout) to try to display the contents of dst is a non-starter. Have you actually looked at what StuffData does? It takes an array of char and a length and returns a codified char array where the first char is the number of bytes (including itself) followed by the chars. If the length of the bytes exceeds 255 then a new chuck is started again with the first byte as the length byte. So "qwerty" gets codified as 0x07 'q' 'w' 'e' 'r' 't' 'y'. 0x00 is treated specially and just gets translated as a new chuck of length 1. So after using StuffData, you pass dst to whatever function you use to actually send the data.
All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.
The destination characters returned by StuffData in dst are NOT a c-style string and are NOT guaranteed to be NULL terminated. So using printf (or cout) to try to display the contents of dst is a non-starter.
I'd say neither the initial buffer nor the destination one is "a c-style string". Both are just byte sequences with some predefined length.
And there is nothing wrong to use printf (or cout) to output their contents. Just use some proper format specification (like %X, "%08X", "%d" or similar) and do output in a loop for each element in the buffer! | <urn:uuid:5231abde-62e3-4b69-813e-44f46b47e859> | 2.71875 | 645 | Comment Section | Software Dev. | 62.143739 |
NASA scientists captured some footage of Plasma Indirection, a plasma shift on the surface of the Sun that looks like huge tornadoes churning. Pretty amazing stuff.
As if it could not make up its mind . . . darker, cooler plasma slid and shifted back and forth above the Sun’s surface seen here for 30 hours (Feb. 7-8, 2012) in extreme ultraviolet light. An active region rotating into view provides a bright backdrop to the gyrating streams of plasma. The particles are being pulled this way and that by competing magnetic forces. They are tracking along strands of magnetic field lines. This kind of detailed solar observation with high-resolution frames and a four-minute cadence was not possible until SDO, which launched two years ago on Feb. 11, 2010. So it’s our 2nd Anniversary! | <urn:uuid:859b72c9-5c36-4f90-b40b-9e16cde07631> | 2.75 | 171 | Personal Blog | Science & Tech. | 62.814615 |
cpphs is a liberalised re-implementation of cpp, the C pre-processor, in Haskell.
Why re-implement cpp? Rightly or wrongly, the C pre-processor is widely used in Haskell source code. It enables conditional compilation for different compilers, different versions of the same compiler, and different OS platforms.
It is also occasionally used for its macro language, which can enable certain forms of platform-specific detail-filling, such as the tedious boilerplate generation of instance definitions and FFI declarations. However, there are two problems with cpp, aside from the obvious aesthetic ones:
* For some Haskell systems, notably Hugs on Windows, a true cpp is not available by default. * Even for the other Haskell systems, the common cpp provided by the gcc 3.x series is changing subtly in ways that are incompatible with Haskell's syntax. There have always been problems with, for instance, string gaps, and prime characters in identifiers. These problems are only going to get worse.
So, it seemed right to provide an alternative to cpp, both more compatible with Haskell, and itself written in Haskell so that it can be distributed with compilers.
This version of the C pre-processor is pretty-much feature-complete, and compatible with the -traditional style. It has two main modes:
* conditional compilation only (--nomacro),
* and full macro-expansion (default).
In --nomacro mode, cpphs performs only conditional compilation actions, namely #include's, #if's, and #ifdef's are processed according to text-replacement definitions (both command-line and internal), but no parameterised macro expansion is performed. In full compatibility mode (the default), textual replacements and macro expansions are also processed in the remaining body of non-cpp text.
#ifdef simple conditional compilation
#if the full boolean language of defined(), &&, ||, ==, etc.
#elif chained conditionals
#define in-line definitions (text replacements and macros)
#undef in-line revocation of definitions
#include file inclusion
#line line number directives
line continuations within all # directives
/**/ token catenation within a macro definition
## ANSI-style token catenation
# ANSI-style token stringisation
__FILE__ special text replacement for DIY error messages
__LINE__ special text replacement for DIY error messages
__DATE__ special text replacement
__TIME__ special text replacement
Macro expansion is recursive. Redefinition of a macro name does not generate a warning. Macros can be defined on the command-line with -D just like textual replacements. Macro names are permitted to be Haskell identifiers e.g. with the prime ' and backtick ` characters, which is slightly looser than in C, but they still may not include operator symbols.
Numbering of lines in the output is preserved so that any later processor can give meaningful error messages. When a file is #include'd, cpphs inserts #line directives for the same reason. Numbering should be correct even in the presence of line continuations. If you don't want #line directives in the final output, use the --noline option.
Any syntax errors in cpp directives gives a message to stderr and halts the program. Failure to find a #include'd file produces a warning to stderr, but processing continues.
Differences from cpp:
In general, cpphs is based on the -traditional behaviour, not ANSI C, and has the following main differences from the standard cpp.
· The # that introduces any cpp directive must be in the first column of a line (whereas ANSI permits whitespace before the #).
· Generates the #line n "filename" syntax, not the # n "filename" variant.
· C comments are only removed from within cpp directives. They are not stripped from other text. Consider for instance that in Haskell, all of the following are valid operator symbols: /* */ */* However, you can turn on C-comment removal with the --strip option.
· Macros are never expanded within Haskell comments, strings, or character constants, unless you give the --text option to disable lexing the input as Haskell.
· Macros are always expanded recursively, unlike ANSI, which detects and prevents self-recursion. For instance, #define foo x:foo expands foo once only to x:foo in ANSI, but in cpphs it becomes an infinite list x:x:x:x:..., i.e. cpphs does not terminate.
Macro definition language
· Accepts /**/ for token-pasting in a macro definition. However, /* */ (with any text between the open/close comment) inserts whitespace.
· The ANSI ## token-pasting operator is available with the --hashes flag. This is to avoid misinterpreting any valid Haskell operator of the same name.
· Replaces a macro formal parameter with the actual, even inside a string (double or single quoted). This is -traditional behaviour, not supported in ANSI.
· Recognises the # stringisation operator in a macro definition only if you use the --hashes option. (It is an ANSI addition, only needed because quoted stringisation (above) is prohibited by ANSI.)
· Preserves whitespace within a textual replacement definition exactly (modulo newlines), but leading and trailing space is eliminated.
· Preserves whitespace within a macro definition (and trailing it) exactly (modulo newlines), but leading space is eliminated.
· Preserves whitespace within macro call arguments exactly (including newlines), but leading and trailing space is eliminated.
· With the --layout option, line continuations in a textual replacement or macro definition are preserved as line-breaks in the macro call. (Useful for layout-sensitive code in Haskell.)
What's New in This Release:
· This release fixes some more obscure corner cases involving parameterised macro expansion within conditionals.
· Internal refactoring affecting parts of the library API has been performed. | <urn:uuid:529d2ec8-9f62-4d26-930e-027e326b701f> | 2.828125 | 1,294 | Documentation | Software Dev. | 31.875616 |
Changing Ideas About The Origin Of Life
By Enrico Uva | August 6th 2012 02:00 AM
For life to begin, a combination of inorganic and organic substances need to evolve biochemistry. When 20th century scientists accepted and elaborated on J.B.S Haldane’s primordial soup hypothesis, their guesses and suggestive experiments centered mostly around the mature field of organic chemistry. But biochemistry as a science was still in its infancy. Their hunches were like those of aliens trying to account for our transition from hunter gatherer-groups to civilization without understanding the roles of agriculture, division of labor and writing.
(1) Primordial Catalysts Were Probably Not Proteins
In the 1960′s, RNA‘s role as a catalyst and replicator was greatly underestimated. Unaware of retroviruses, or at least of their reproductive mechanism, biochemists believed that information only flowed from DNA to RNA, and they perceived proteins to be the only biological catalysts. After the discovery of ribozymes revealed that tertiary RNA molecules could speed up their own production, it was hypothesized that these were life’s first catalysts because they could have evolved from single-stranded RNA molecules, which are structurally simpler than both DNA and proteins.
But the current popular notion that RNA was essentially the sole primeval replicator and catalyst has also come under attack. As an alternative, the first catalysts may have also included inorganic ions. Hydrothermal vents are rich in iron (II) sulfide (FeS) and nickel (II) sulfide, both of which can speed up biochemical reactions. In existing hydrothermal bacteria and archaebacteria, these compounds are part of protein complexes, but the ions are the reactive catalytic centers for a remarkable exergonic reaction. Hydrogen gas from the vents combines with dissolved carbon dioxide in the sea (and an acetyl-less CoA ) to produce water and acetylCoA (a key molecule involved in releasing energy from sugars; in fatty acid synthesis etc). The overall reaction releases 59 kJ of free energy for every 2 moles of fixed CO2, enough to drive the synthesis of ATP.
Another argument against RNA exclusivity from Lane, Allen and Martin is that each time RNA makes a copy of itself in a “primordial soup” its concentration drops so the rate of reaction can only be maintained if nucleotides are continuously replenished. This brings us to the issue of energy.
(2) First Energy Source Likely Involved Proton Gradients
In the same way that a room only remains tidy and dustless with continuous effort, life forms are capable of maintaining order only in the presence of a continuous energy supply. Even before life arises, the required conversions of small molecules to larger ones are endothermic. Whereas the original hypotheses were careful enough to exclude oxygen from the original mix because an oxidizing atmosphere would break up newly made molecules, the irony is that the proposed energy sources, ultraviolet and lightning, would also destroy newly synthesized molecules. The excessive heat and low pH‘s from deep, volcanic hydrothermal vents do not lead to a viable energy alternative.
But Lane, Miller and Allen point out that there is another hydrothermal vent which gets its heat from the mid Atlantic’s tectonic boundaries, known as the Lost City, where olivine mineral (a combination of magnesium and iron silicates) turns to surpentine (hydroxylated iron and magnesium silicates).
This is the source of hydrogen gas used by the previously mentioned bacteria to “fix” carbon dioxide into acetyl, a part of a vital metabolite. The hydroxides formed are not inconsequential because, with the help of simple membranes, they provide a natural pH-gradient, essentially a voltage, one that was more pronounced in ancient seas due to CO2 concentrations that were 1000 times higher than their modern counterpart. Remarkably that gradient is comparable to the one created by the biochemical processes in today’s cells.
Forty years ago, this idea that chemiosmosis was the energy-provider for earth life’s first cells could not be put forth because no one understood how the universal reaction-facilitator, ATP(adenosine triphosphate), was made from ADP(adenosine diphosphate). But given that proton gradients power ATP production in all kingdoms of life: in respiration, photosynthesis and in rotating motors of bacterial flagella, the hypothesis is now plausible. The enzyme ATP synthase is a molecular machine whose “blades” are rotated by H+ that are put in motion by coulombic repulsion. The enzyme-portion attracts and combines ADP with a phosphate group and the spinning nanomachine releases the ATP.
DiMauro has spent 10 years working on the chemistry of 1-carbon amide formamide (H2NCOH), subjecting it to a variety of conditions and mineral catalysts. He has produced all four nucleic acids and a variety of carboxylic acids. What works best is when he uses a pH of 9 to 10 and temperatures in the 80–160 ◦C range, conditions that are found in non-volcanic hydrothermal vents.
(3) Knowledge of New Bacterial Kingdoms Downplays Role of Fermentation In First Cells
The authors of How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays. January 2010 refute the popular notion that fermentation was used by the first cells to release chemical energy from food molecules. Aside from the idea that fermentation seems to be a derived chemical process, when comparing bacteria to archaea, there are also major differences in the gene sequences of fermentation enzymes. On the surface they seem like similar processes, but in reality the release of energy in oxygen’s absence evolved separately and independently. It’s essentially convergent evolution, the way Old World Euphorbia and New World cacti have similar adaptations but are not related.
Clostridia-type fermentations (Clostridia are sulfite reducing bacteria that include tetanus-producing bacteria), which represent ancient lineages, actually involve chemiosmosis, which of course exploits ion gradients across the cytoplasmic membrane and rotor–stator type ATPases (enzymes that cleave ATP to place a good leaving group on otherwise nonreactive molecules). The same is true of fermentation in most free-living anaerobic bacteria.
Writing in 1969, Calvin wrote:
As long as we are limited to biology as it is on the earth, it is going to be difficult for us to be sure that such a system occurred in the way described in this book. We shall have to find other places in the universe, preferably nearby, in which this process is going on and has not gone all the way, so that we can observe it at some other stage of its development. this is why I am interested in lunar and planetary exploration.
In four decades no such places have been found yet, but at least something esoteric has been discovered at the bottom of our own oceans. It’s far from direct evidence, which of course eludes everyone because the molecular precursors to primordial life left no traces. But along with more detailed knowledge of biochemistry, the Lost City has inspired hypotheses that bring us closer to a non-fictitious narrative of our chemical history.
How did LUCA make a living? Chemiosmosis in the origin of life
LAM BioEssays | pdf file
- William F. Martin Edited by Miguel Teixeira and Ricardo O. Louro Hydrogen, metals, bifurcating electrons, and proton gradients: The early evolution of biological energy conservation Febs Letters Volume 586, Issue 5, 9 March 2012, Pages 485–493
- Nick Lane, John F. Allen, William Martin. How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays. January 2010 (whole article can be read free of charge)
- Michael J. Russell, William Martin. The Rocky Roots of the Acetyl-coA Pathway TRENDS in Biochemical Sciences Vol.29 No.7 July 2004 (whole article can again be read free of charge)
- Calvin, M. (1969). Chemical evolution: Molecular evolution towards the origin of living systems on the earth and elsewhere. Oxford: Clarendon Press. QH325 .C26
Enrico Uva (2012). Changing Ideas About The Origin Of Life Science 2.0 | Chemical Education
Tracing Knowledge Notification | Ειδοποίηση Στα ίχνη της Γνώσης
of the original post, out of respect to the source and readers.
Please follow the link for references and more informations.
της πρωτότυπης δημοσίευσης με σεβασμό στην πηγή και στους αναγνώστες.
Παρακαλώ επισκεφθείτε τον σύνδεσμο για περισσότερες πληροφορίες. | <urn:uuid:cba9b995-2e8f-4763-b024-81aace16e109> | 3.015625 | 2,026 | Personal Blog | Science & Tech. | 34.639729 |
If the Reynolds number is small enough (Re<<1), then two fluids can flow in parallel in direct contact, exchanging momentum and species only by diffusion. If the interface is
stable, then this system can be used as a filter. In this problem, the flow fields in both fluids are found.
2008 Carlos Martinez and Matthew John M. Krane
Difficulty level: Junior; Solution time: 1 hour; Reference: J. P. Brody,et al., "Biotechnology at Low Reynolds Numbers," Biophysical Journal., v.719, pp. 3430-3441, | <urn:uuid:fbd18c75-6e77-4a88-926e-69a8f121a6c1> | 2.921875 | 122 | Academic Writing | Science & Tech. | 73.423286 |
Question: If the work required to stretch a spring 1 ft beyond its natural length is 9 ft-lb, how much work W is needed to stretch it 10 in. beyond its natural length?
So my teacher today gave us some physics equations and said to do this homework. Im a little stuck on this, usually they give us the force required to stretch a spring, not the work. Here is what i tried:
Then I did F=KX (hooke's law) to solve for the k constant of the spring
9 = K * 1 ft
K = 9
So I now know that F = 9X (equation for force of a spring when you know the k constant of that spring)
And then i said the:
INTEGRAL of: 9x from 0-10/12 = Total work needed to stretch the spring 10inches.
I get 7.25, but this answer is wrong. | <urn:uuid:04a804c3-a025-48b1-ad1e-93aa63f2ec07> | 2.71875 | 192 | Q&A Forum | Science & Tech. | 93.915541 |
The trivial ring, or zero ring, is the ring with a single element, which is both and . We usually denote the trivial ring as or , even though or would make as much sense. It is the only ring in which , by the proof
x = 1 x = 0 x = 0 .
The trivial ring is the terminal object in Ring. It is both terminal and initial (hence a zero object) in the category of nonunital rings, but it is not initial in itself (defined as the category of unital rings and unital ring homomorphisms). In fact, there are no unital ring homomorphisms from the trivial ring to any nontrivial ring!
The trivial ring is an example of a trivial algebra. | <urn:uuid:8bf3cc72-0d62-43cb-9094-dd700a025e2b> | 3.21875 | 153 | Knowledge Article | Science & Tech. | 64.258898 |
Four jewellers possessing respectively eight rubies, ten saphires,
a hundred pearls and five diamonds, presented, each from his own
stock, one apiece to the rest in token of regard; and they. . . .
A, B & C own a half, a third and a sixth of a coin collection.
Each grab some coins, return some, then share equally what they had
put back, finishing with their own share. How rich are they?
Pick a square within a multiplication square and add the numbers on
each diagonal. What do you notice?
A paradox is a statement that seems to be both untrue and true at the same time. This article looks at a few examples and challenges you to investigate them for yourself.
We have exactly 100 coins. There are five different values of
coins. We have decided to buy a piece of computer software for
39.75. We have the correct money, not a penny more, not a penny
less! Can. . . .
Write down a three-digit number Change the order of the digits to
get a different number Find the difference between the two three
digit numbers Follow the rest of the instructions then try. . . .
What does logic mean to us and is that different to mathematical logic? We will explore these questions in this article.
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
These formulae are often quoted, but rarely proved. In this article, we derive the formulae for the volumes of a square-based pyramid and a cone, using relatively simple mathematical concepts.
The sums of the squares of three related numbers is also a perfect
square - can you explain why?
This jar used to hold perfumed oil. It contained enough oil to fill
granid silver bottles. Each bottle held enough to fill ozvik golden
goblets and each goblet held enough to fill vaswik crystal. . . .
Spotting patterns can be an important first step - explaining why it is appropriate to generalise is the next step, and often the most interesting and important.
Can you find all the 4-ball shuffles?
This addition sum uses all ten digits 0, 1, 2...9 exactly once.
Find the sum and show that the one you give is the only
Find the missing angle between the two secants to the circle when
the two angles at the centre subtended by the arcs created by the
intersections of the secants and the circle are 50 and 120 degrees.
The problem is how did Archimedes calculate the lengths of the sides of the polygons which needed him to be able to calculate square roots?
Here are some examples of 'cons', and see if you can figure out where the trick is.
Baker, Cooper, Jones and Smith are four people whose occupations
are teacher, welder, mechanic and programmer, but not necessarily
in that order. What is each person’s occupation?
Take any two numbers between 0 and 1. Prove that the sum of the
numbers is always less than one plus their product?
Find the area of the annulus in terms of the length of the chord
which is tangent to the inner circle.
I am exactly n times my daughter's age. In m years I shall be exactly (n-1) times her age. In m2 years I shall be exactly (n-2) times her age. After that I shall never again be an exact multiple of. . . .
Can you convince me of each of the following: If a square number is
multiplied by a square number the product is ALWAYS a square
Factorial one hundred (written 100!) has 24 noughts when written in full and that 1000! has 249 noughts? Convince yourself that the above is true. Perhaps your methodology will help you find the. . . .
If you take two tests and get a marks out of a maximum b in the first and c marks out of d in the second, does the mediant (a+c)/(b+d)lie between the results for the two tests separately.
Use the numbers in the box below to make the base of a top-heavy
pyramid whose top number is 200.
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
If you know the sizes of the angles marked with coloured dots in
this diagram which angles can you find by calculation?
There are four children in a family, two girls, Kate and Sally, and
two boys, Tom and Ben. How old are the children?
Consider the equation 1/a + 1/b + 1/c = 1 where a, b and c are
natural numbers and 0 < a < b < c. Prove that there is
only one set of values which satisfy this equation.
In the following sum the letters A, B, C, D, E and F stand for six
distinct digits. Find all the ways of replacing the letters with
digits so that the arithmetic is correct.
Semicircles are drawn on the sides of a rectangle ABCD. A circle passing through points ABCD carves out four crescent-shaped regions. Prove that the sum of the areas of the four crescents is equal to. . . .
Let a(n) be the number of ways of expressing the integer n as an
ordered sum of 1's and 2's. Let b(n) be the number of ways of
expressing n as an ordered sum of integers greater than 1. (i)
Calculate. . . .
Points A, B and C are the centres of three circles, each one of
which touches the other two. Prove that the perimeter of the
triangle ABC is equal to the diameter of the largest circle.
Carry out cyclic permutations of nine digit numbers containing the
digits from 1 to 9 (until you get back to the first number). Prove
that whatever number you choose, they will add to the same total.
Janine noticed, while studying some cube numbers, that if you take
three consecutive whole numbers and multiply them together and then
add the middle number of the three, you get the middle number. . . .
Eight children enter the autumn cross-country race at school. How
many possible ways could they come in at first, second and third
Here are three 'tricks' to amaze your friends. But the really
clever trick is explaining to them why these 'tricks' are maths not
magic. Like all good magicians, you should practice by trying. . . .
Six points are arranged in space so that no three are collinear.
How many line segments can be formed by joining the points in
What is the area of the quadrilateral APOQ? Working on the building
blocks will give you some insights that may help you to work it
I start with a red, a green and a blue marble. I can trade any of
my marbles for two others, one of each colour. Can I end up with
five more blue marbles than red after a number of such trades?
Nine cross country runners compete in a team competition in which
there are three matches. If you were a judge how would you decide
who would win?
From a group of any 4 students in a class of 30, each has exchanged
Christmas cards with the other three. Show that some students have
exchanged cards with all the other students in the class. How. . . .
A standard die has the numbers 1, 2 and 3 are opposite 6, 5 and 4
respectively so that opposite faces add to 7? If you make standard
dice by writing 1, 2, 3, 4, 5, 6 on blank cubes you will find. . . .
A little bit of algebra explains this 'magic'. Ask a friend to pick 3 consecutive numbers and to tell you a multiple of 3. Then ask them to add the four numbers and multiply by 67, and to tell you. . . .
I start with a red, a blue, a green and a yellow marble. I can
trade any of my marbles for three others, one of each colour. Can I
end up with exactly two marbles of each colour?
Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number.
Cross out the numbers on the same row and column. Repeat this
process. Add up you four numbers. Why do they always add up to 34?
A 'doodle' is a closed intersecting curve drawn without taking
pencil from paper. Only two lines cross at each intersection or
vertex (never 3), that is the vertex points must be 'double points'
not. . . .
Can you fit Ls together to make larger versions of themselves?
How many different cubes can be painted with three blue faces and
three red faces? A boy (using blue) and a girl (using red) paint
the faces of a cube in turn so that the six faces are painted. . . .
A connected graph is a graph in which we can get from any vertex to
any other by travelling along the edges. A tree is a connected
graph with no closed circuits (or loops. Prove that every tree. . . . | <urn:uuid:cecfc178-7e3d-44c4-97c5-0ea96f190d58> | 2.828125 | 1,998 | Content Listing | Science & Tech. | 75.944028 |
Series and parallel
|This is a series circuit, showing the location of an ammeter and voltmeter.
The current is the same at all points along the circuit
The sum of the voltage across the individual components is equal to that at the power supply.
|At the junctions, the current splits, but then rejoins at the final junction.|
Voltage across each component stays the same
Parallel circuits are used in christmas lights because, if one light breaks, the electricity will flow the other route.
This is an important relationship between voltage, resistance and current. It is very simple and outlined in a triangle below, where V = IR; and some units are explained. | <urn:uuid:641d1f77-2f8f-4eaa-ae24-6786f88ef182> | 3.71875 | 144 | Knowledge Article | Science & Tech. | 45.533176 |
Exercise Template Haskell
In this exercise, we will have a closer look at Template Haskell. The hierarchical libraries
that are distributed with GHC include functions for writing Template Haskell code. Have a look
at the modules Language.Haskell.TH
You may want to consult the notes on Template Haskell
and Section 7.6
from the GHC User's Guide.
To use Template Haskell code from the ghci interpreter, you need to use the flag
This exercise was inspired by research on automatically repairing ill-typed expressions. For some typical programming errors,
a more advanced compiler could offer advise to a programmer how to correct an expression with a type error. In fact, the
offers such a facility. You are asked to write a number of functions that
can be used to correct an expression (details are given below).
You are given two Haskell modules as a starting point.
- Correct.hs: contains the functions you have to define. Currently, these functions are set to
- Test.hs: contains a number of functions for testing your implementation. In some cases, the expected answer is provided. In the other cases, the test corresponds to an optional question. Note that you also have to make changes to this module because the compiler must be informed about which parts are meta-programs.
Submit your solution by sending me the two changed Haskell modules, and give short
answers to the questions posed. Good luck!
1. Removing an argument
The following expression contains a type error.
test0 = filter even () [1..10]
One possibility to get rid of the type error is removing the
from the application. We will use the following convention:
corresponds to the function of the application (
to its first argument (
), etc. Implement a function
that is given a number
(greater than or equal to
), such that it conceptually ignores the
(remove 2) filter even () [1..10]
should yield the same result as
filter even [1..10]
n = 2
write a (lambda) expression by hand that behaves as
- Why can't
remove be defined as a normal (non-Template) Haskell function?
remove n with
n = 0 is a special case, since it removes the function of an application rather than some argument. Give an intuition for the meaning of
- What happens if we choose
n = 5 for the example presented above (the function
filter is supplied only three parameters)?
2. Inserting an argument
In the following expression, the higher-order function
should be given an initial value.
This expression can be repaired by inserting a second parameter.
test2 = foldr ((:) . toUpper) "afp 2005"
We will use the same convention for assigning numbers to the parameters.
(insertHole 2) foldr ((:) . toUpper) "afp 2005"
should be equal to
foldr ((:) . toUpper) hole "afp 2005"
is the polymorphic "error function" predefined in the module
Optional part for 2:
More ideally, we pass an additional parameter to
, which is the value to be inserted. For instance,
(insert 2 ) foldr ((:) . toUpper) "afp 2005"
foldr ((:) . toUpper) "afp 2005"
. Explain your solution.
3. Permuting arguments
In the next example, the arguments to
are supplied in the wrong order.
test4 = foldr 0 (+) [1..10]
A permutation can be represented by a value of type
. For instance, the permutation
swaps the first and the second
argument of a function. Give an implementation of
for permuting arguments.
- Explain the difference between
permute [0,2,1] and
- The value
[0,1,1] is not a valid permutation, but it can be passed to
permute. What kind of corrections can we make by passing invalid permutations?
4. Inserting parentheses
Take a look at the following expression.
test5 = length filter even [1..10]
A common mistake made in functional programming is to forget some parentheses. The expression given above can be fixed by inserting two parentheses,
length (filter even [1..10])
. This is the purpose of the function
that you have to write.
This function should be supplied two integers: the first indicates the location of the opening parenthesis, the second integer indicates how many
parameters are enclosed by the parentheses. We use the convention that location
corresponds to the position just before the function
(in our example,
corresponds to the position between the function and its first argument (in our example, between
, we thus need
parens 1 3
- What can you say about the values of the two integers that can be supplied to
parens? Are there special cases?
5. Removing parentheses (optional)
In a similar way, we would like to remove a pair of parentheses.
foldr ((++) ["Template", "Meta", "Programming"])
Following our line of reasoning, we could fix the type error by using
unparens 1 3
. Can you give a definition for
6. Library for correcting expression
Template Haskell offers a facility to splice in declarations. Therefore, we could automatically bring the functions
, etcetera into the top-level scope of a module. These specialized functions can be used as any normal Haskell function.
Of course, we can make use of the general
function (see Step 2).
Bring (a limited number of) specialized functions for
into the scope.
Optional part for 6:
Do the same for the other correcting functions.
7. Extending the library (optional)
Of course, there are more mistakes resulting in a type error that can be fixed automatically.
Can you think of more (useful) correcting functions? | <urn:uuid:7a7d3605-cf73-43fb-8116-8c8e8341ec29> | 2.78125 | 1,273 | Tutorial | Software Dev. | 53.184547 |
February 9, 2000
Java Programming, Lecture Notes # 302
by Richard G. Baldwin
This lesson is primarily concerned with the use of the java.awt.geom.Point2D class. It also illustrates the use of nested top-level classes in the Java 2D Graphics API. This is a concept that was explained in an earlier tutorial lesson. If you aren’t familiar with this concept, you should review the earlier tutorial that explains it.
The concept of a point is central to most graphics models. A point is a specification of a particular location in space. It has neither height, nor width, nor depth. Therefore, it cannot be rendered on your computer screen, although it might be possible to render a pixel on your screen that occupies a space generally specified by the point.
Although points can exist in three-dimensional space, that is not our interest in the current series of lessons. This series of lessons in concerned with the Java 2D (two-dimensional) API. Hence, a point in our 2D space represents a location in that space commonly specified by a pair of coordinate values, horizontal (x) and vertical (y).
You may already be familiar with the notion of performing graphic operations in Cartesian coordinates. This is similar, except in Cartesian coordinates, the positive direction of y-displacement is normally up, while in our current frame of reference, the direction of positive y-displacement is down. As in typical Cartesian coordinates, the direction of positive x-displacement is to the right.
So, an object of the java.awt.geom.Point2D class encapsulates a pair of coordinate values that specify a location in our coordinate system. Many of the graphic objects that we will encounter later as we continue to pursue the Java 2D Graphics API are constructed on a foundation of points. For example, four points could be used to specify the corners of a rectangle, and three points could be used to specify the apexes of a triangle. A large number of points could be used to specify a curved line made up of many short straight-line segments.
The Point2D class demonstrates the use of nested top-level classes, which is an inheritance concept used throughout the 2D API. This is a concept where one or more subclasses are defined as static classes inside their superclass. The details of this concept were presented in an earlier tutorial lesson.
While an object of the Point2D class encapsulates the coordinates of a location in space, that class alone doesn’t specify how the coordinate values are stored. Rather, two nested subclasses named Point2D.Double and Point2D.Float are used to actually store the coordinate information. An object of the first subclass stores the coordinate information as type double while an object of the second subclass stores the coordinate information as type float. Apparently, however, it is usually satisfactory to treat those objects as type Point2D, because many of the standard methods that use an object of the type Point2D will determine the actual subclass type and then behave accordingly.
The Java 2D API became available with the release of JDK 1.2. Prior to that time, the Java AWT included a class named Point that could also be used to specify the coordinates of a location in space. Objects of the Point class have, since the beginning, specified the coordinate values as type int, and that is still the case. With the release of the 2D API, the Point class now extends the Point2D class. However, Point is not a nested subclass of Point2D. It is simply a subclass of Point2D.
The Point2D class provides several methods that are inherited by its subclasses, and can be used to operate on objects instantiated from those subclasses. Most of the methods have several overloaded versions. Generally the methods provide the following capabilities:
The sample program that I will present later will make use of some of these capabilities.
The two nested subclasses provide (apparently overridden versions of) the set and get methods for setting and getting the coordinate values as the appropriate type. The Point2D.Float class provides set methods for input parameters of either type double or type float. Presumably if the coordinate values are provided as type double, they are converted to type float and saved as that type.
Curiously, the get methods of the Point2D.Float class do not provide an overridden version to return coordinate values of type float. Rather, they return the coordinate values as type double even if this means returning inaccurate double results. This is illustrated in the sample program that I will present later.
Both of the nested subclasses provide an overridden toString() method that returns a String that represents the type of object and the coordinate values of the point.
The Point class provides methods to accomplish generally the same behavior as described above for the new classes in the 2D API, although in some cases the syntax is different. In addition, the Point class provides methods to
Since the Point class is not new to the Java 2D API, I probably won’t have much to say about it in this series of lessons. The biggest difference between the Point class, which has existed since JDK 1.0, and the Point2D class that was released with JDK 1.2 is:
The sample program presented later will illustrate the use of the nested subclasses named Point2D.Double and Point2D.Float.
This sample program, named Point01.java is designed to illustrate the use of the two nested top-level classes that are contained in, and extend the class named Point2D. I will break the program into fragments for discussion. A complete listing of the program is provided at the end of the lesson.
The first fragment (Figure 1) shows an import directive to remind us that we are working with a class that belongs to the java.awt.geom package.
This fragment also shows the beginning of the definition of the controlling class named Point01. Two instance variables are declared, each of type Point2D. Later, these instance variables will be used to contain references to two objects, one of each of the nested subclass types.
Figure 2 shows the beginning of the main() method. This fragment also shows the instantiation of an object of the controlling class, and the storage of a reference to this object in the local reference variable named thisObj. This object contains the two instance variables of type Point2D declared above, which can be used to refer to objects of the nested subclass types.
Figure 3 instantiates an object of the nested subclass, Point2D.Double and stores a reference to that object in an instance variable named doublePointVar, which is an instance variable of the object of the controlling class (thisObj). Note that this reference variable is not of the actual type of the object, but rather is of the type of its superclass named Point2D. This is possible because in Java, a reference to an object can be stored in a reference variable of the actual class of the object, or of any superclass of the class of the object.
When the new object of the Point2D.Double class is instantiated, the x and y coordinate values are initialized with the following values respectively:
At least these would be the values if we had infinite precision. In reality, these values are stored in the object with the precision afforded by the double type
Similarly, Figure 4 instantiates an object of the Point2D.Float class, and stores its reference in a different instance variable of the controlling class named floatPointVar. Again, this variable is not of the actual type of the object, but rather is of the superclass of the object, Point2D.
This is a common theme used throughout the Java 2D API. Objects are frequently instantiated from a nested subclass type and the references to those objects are stored in reference variables of the superclass type.
When this object is instantiated, its coordinate values are initialized with the same values described above (never ending 3’s and 6’s) except that in this case, the values are stored with precision afforded by the float type, which is considerably less than the precision afforded by the double type.
Note that a (float) cast is required to force the result of the division to be of type float in order to satisfy the parameter type requirements of the constructor for the Point2D.float class.
Figure 5 applies the getX(), and getY() methods to the two instance variables containing references to the two objects of the nested-subclass types to get and display the coordinate values stored in those objects.
The output produced by this code fragment follows:
Data from the object of type Point2D.Double
Data from the object of type Point2D.Float
As mentioned earlier, the get methods for the Point2D.Float class return the stored coordinate information as type double. However, as you can see, the returned values are not accurate beyond about the seventh significant digit in this case (I have highlighted the erroneous values in red). The double values returned by the get method for the Point2D.Double class are accurate through about sixteen significant digits.
This fragment also ends the main() method and ends the controlling class.
A listing of the complete program is provided in Figure 6
Richard Baldwin is a college professor and private consultant whose primary focus is a combination of Java and XML. In addition to the many platform-independent benefits of Java applications, he believes that a combination of Java and XML will become the primary driving force in the delivery of structured information on the Web.
Richard has participated in numerous consulting projects involving Java, XML, or a combination of the two. He frequently provides onsite Java and/or XML training at the high-tech companies located in and around Austin, Texas. He is the author of Baldwin's Java Programming Tutorials, which has gained a worldwide following among experienced and aspiring Java programmers. He has also published articles on Java Programming in Java Pro magazine.
Richard holds an MSEE degree from Southern Methodist University and has many years of experience in the application of computer technology to real-world problems.
Copyright 2000, Richard G. Baldwin. Reproduction in whole or in part in any form or medium without express written permission from Richard Baldwin is prohibited. | <urn:uuid:db027679-2a28-4a09-bf01-fb86ea8daeba> | 4.21875 | 2,134 | Truncated | Software Dev. | 46.206797 |
This is simple java programming tutorial . In this section you will learn how to calculate the sum of three numbers by using three static variables.
Description of this program:
In this section we will see how to calculate three integer number . First of all define class name "StaticSum". For this we have defined three static variables of type int. To assign the value of the numbers define a method main. Remember we are overloading the main method. This method will take three arguments. The values will be added in the Addition method which we have declared in our program. Now call the main method. To get the values of the three numbers call the overloaded method main() inside main() method. To add those values call the Addition method which will return the integer value and the value will be displayed to the user by using the println() method of the System class.
Here is the code of this program
If you are facing any programming issue, such as compilation errors or not able to find the code you are looking for.
Ask your questions, our development team will try to give answers to your questions. | <urn:uuid:397d6c3f-0bb4-4203-b5ef-0cd1b457eb19> | 4.3125 | 225 | Tutorial | Software Dev. | 59.506731 |
The script can be reduced in code for general usage and without comments it is only a few lines.
The advantages of using a script:
- The output format can be customized.
- It can be written to output the statistic either to a message box, a new file, to output window, or even into the file itself.
- The statistic output can be produced also for the entire file, or only selected text, or for selected text and entire file.
- The word delimiters can be customized and it is possible to filter the word list before counting, for example to ignore strings with a single character like a or I.
Summarized, using a script gives a user with good skills in writing scripts the possibility to customize the statistic output to personal needs. If such a customization is not required or a user has no skills in writing scripts, calling the word count tool is definitely the better solution. | <urn:uuid:53ffa54e-32aa-4afe-aacc-10f55492a3f7> | 2.8125 | 187 | Comment Section | Software Dev. | 42.351529 |
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2000 March 8
Explanation: As the robot spacecraft NEAR lowers itself toward asteroid 433 Eros, more surface details are becoming visible. Last week's maneuvers brought NEAR to within 204 kilometers of the floating mountain's surface. With increased resolution, NEAR's camera then documented Eros' unusual shape, craters large and small, boulders, and mysterious grooves similar to asteroid Gaspra and Martian moon Phobos. If you could stand on Eros, you would still be too small to be visible on this recent image, which shows features as small as 20 meters across. However, you would feel gravity only 1/1000 that on Earth, so that you could easily jump over even this large 5 kilometer wide crater.
Authors & editors:
Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U. | <urn:uuid:853c31be-8914-4b9e-ac6e-b0bd88dc5861> | 3.109375 | 226 | Knowledge Article | Science & Tech. | 48.566456 |
The Fine Art of Waddling
Natural History, March 2001
When Tim Griffin and Rodger Kram set out to study how penguins walk, they didn’t expect to be impressed. Compared with long-legged ostriches striding across a plain, waddling penguins come up short. Underwater they may be able to race like torpedoes in tuxedos, but on land they are more apt to evoke laughter than to inspire respect.
Previous research on penguins seemed to back up the laughter with hard numbers. Pound for pound, a penguin on land uses twice as much energy as other animals of its size to walk a given distance. Scientists laid the blame for this expense on waddling, the (presumably) energetically costly business of
the bird’s throwing its body first to one side and then to the other as it walks.
Griffin and Kram, both at the University of California, Berkeley, decided to test the assumption by measuring the work involved in waddling. So they filmed emperor penguins walking over a force-sensitive plate. Their data enabled them to calculate not just the force of each step but also the direction in which the force was acting and how fast the penguins were moving.
Similar studies on humans and other land animals have shown that walking is a surprisingly efficient way to move. Planting a foot in front of your body as you walk forward, you rise up slightly. Once your body is positioned directly above the foot, you start to fall forward and downward. In this process, much of the kinetic energy of your forward movement is turned into gravitational energy, which is then transformed into moving forward again. The same process occurs when a pendulum converts the energy it derives from moving side to side into moving upward against gravity A walking person is like a pendulum turned upside down. Taking advantage of gravity this way saves lots of energy. Experiments have shown, for example, that a person’s muscles need to supply only 35 percent of the work they would have to perform if there were no inverted pendulum involved. As the walker “falls” with each step, the muscles manage to recover 65 percent of the energy they put into a stride.
Griffin and Kram were amazed to discover that in this respect the penguins were actually superior to humans, recovering up to 80 percent of the energy they put into each step among the highest rates ever recorded for any animal. How is this possible? Penguins not only rise and fall along the line in which they are walking (as we do); they also swing their bodies from side to side like pendulums. This side-to-side waddling provides additional energy for fighting gravity.
Energy from this sideways movement helps the penguin reach an upright position when only one leg is on the ground. As the bird swings back-or rather, falls-to the opposite side, it uses gravitational energy both to move sideways and to step forward.
Biologists have given waddling a bad rap, suggest Griffin and Kram. Penguins do pay a steep price to walk, but the researchers claim that waddling is not to blame. Instead, they propose, the trouble comes from having such short legs. Long-legged animals with longer strides maintain contact with the ground for more time during each step than do short-legged creatures. This allows a long-legged creature to use slower-working, more efficient muscle fibers. An emperor penguin is a hefty bird, weighing about forty pounds-in the same range as the flightless South American rhea, which is similar to an ostrich. But the emperor’s legs are only one-third the length of the rhea’s, or only about as long as those of the guinea fowl, a bird weighing only three pounds. Moving a rhea’s body around on a guinea fowl’s legs, a penguin has no choice but to use a lot of energy.
Like many animals, penguins are caught in a biomechanical bind. With their flipperlike wings, they are well adapted for swimming, and their short legs may help reduce drag underwater. But because they’re birds and not fish, penguins cannot completely give up life on land, where they find mates, lay their eggs, and raise their chicks. Emperors are, in fact, champion walkers, traversing up to 150 miles of frozen sea ice to reach their winter rookeries. Far from wasting energy, waddling may help keep a penguin alive.
Copyright 2001, Carl Zimmer. Reproduction or distribution is prohibited without permission. | <urn:uuid:f7b03d25-d0e8-4e42-aac6-3ea3b96c51ba> | 3.671875 | 955 | Knowledge Article | Science & Tech. | 49.515705 |
James Cameron’s descent to the Challenger Deep – we have adventure, intrigue, and a great story for the media. But we also have an amazing opportunity for SCIENCE!
Despite a faulty hydraulics hampering sample collections, the Deepsea Challenger managed to grab half a sediment core – a cupful of muddy, watery ooze from the deepest point in the ocean:
“Jim recovered about 50 millileters of muddy seawater that I gleefully processed for culturing and for genomic studies,” Doug Bartlett, chief scientist for the DEEPSEA CHALLENGE project, said in an email to National Geographic News.
“Can’t wait to see what new critters (Bacteria, Archaea, and fungi) that we discover,” said Bartlett, a marine biologist at the Scripps Institution of Oceanography in San Diego, California.
Some might lament Cameron’s technical difficulties and shake their heads at the lost sampling opportunity. But even half a sediment core will reveal precious information about one of the last frontiers on earth. We have plenty to work with.
In molecular terms, 50 milliliters is a LOT of sample. Normally my lab protocols call for 200 microliters of mud for a single extraction of environmental DNA. So with his one cup of mud, James Cameron can do 250 DNA extractions–and you only need one or two extractions (maybe a few more, which are then concentrated and pooled if there isn’t a lot of DNA because of few animals or small amounts of tissue) before you can move forward and produce gene sequences, using high-throughput platforms such as the Illumina Hi-Seq.
So even with a single drop of sample, you can obtain hundreds of millions of DNA sequences from species inhabiting the Challenger Deep. And there’s no restriction to any particular taxonomic group. The power of DNA means that we will be able to characterize deep sea life across all known domains–bacteria, archaea, eukaryotes, and even viruses.
One of the first things to sequence will be ribosomal RNA, a conserved gene that essentially serves as a molecular barcode (since every cell needs its ribosomes to survive!) and allows us to place species on branches within the Tree of Life. By comparing ribosomal genes from the Challenger Deep to those from species that have already been studied, we’ll be able to place this deep-sea community in an evolutionary context and investigate how life might have evolved in the ocean depths. What other environments contain closely related species? How divergent are the ribosomal genes in the Mariana Trench (and from this, we can start guessing how long these trench communities have been isolated–if at all–from other deep sea habitats)? Is the Challenger Deep harboring any novel, undiscovered branches on the Tree of Life?
We’ll also get an environmental metagenome from this sequencing effort — randomly sequenced pieces of DNA representing every species’ genome lurking in that muddy sample. This will give us an expanded view compared to ribosomal genes, and we can start inferring things about community function. What type of genes are prevalent in the deepest, darkest ocean trench? The types of genes we find can tell us a lot about how a community survives (does it rely on scarce food sinking from above, or have species adapted to use alternative metabolic pathways such as chemosynthesis), and how an assemblage of organisms might inherently depend on each other to survive in an extreme environment. If the community in the Challenger Deep is not too complex (a handful of species, or a good pool of abundant ones) and the scientists at Scripps decide to sequence a LOT of DNA from this precious mud (a couple runs on the Illumina Hi-Seq can get you close to a billion DNA sequences), then it is possible that we might be able to assemble whole genomes from this random sample of mud. So instead of a ribosomal gene we’ll potentially have an entire genome as a molecular barcode for some microbial species–and for inferring how evolution happened in the deep-sea, a genome will give you a lot more information than just a short ribosomal sequence.
In addition to extracting DNA we can also take out the RNA and look at patterns in molecules such as mRNA (expressed transcripts of genes, if you remember back to high school biology). So in addition to finding out who’s there and what their genomes say they can do, RNA can tell us what these species might actually be doing. Remember that there’s a lot of “junk” DNA sitting around in any given genome (and you’ll get a lot of this information from a random environmental metagenome sequencing), so its always good to have additional information about what type of genes are being expressed. Now the pressure and temperature changes will have sent most species’ cellular machinery into overdrive during Cameron’s ascent to the surface, and we may get more of a “help, help , I’m dying” reaction from the community. Its always tricky to interpret gene expression. But in many ways, any data is good data. Gene expression from the Challenger Deep may tell us some very exciting things.
Doug Bartlett from Scripps also indicated plans to try and culture some microorganisms from Cameron’s sample — while there’s no guarantee of success (the pressure change and inherent difficulty in culturing microbes both present significant hurdles), any cultured species would be closely scrutinized and provide mountains of data for years to come. Not only could we sequence genomes from cultured species, but we could organize sophisticated experiments to figure out exactly what nutrients they need, their metabolic pathways, and novel compounds produced that all contribute to adaptation in the deep sea. We may soon have alien life growing in a Southern California lab!
These approaches alone will give you an unprecedented view into life in the Mariana Trench. But we can still do more with that half core.
Cameron noted that the ocean floor he saw was lunar-like, smooth and featureless–but that doesn’t mean the environment is exclusively the realm of microbes. In fact, we know that bigger (albeit still microscopic) species like foraminifera do live in the Challenger Deep (Todo et al., Science, 2005), and Cameron saw amphipods swimming around before the sample had even been returned to the lab. Which means we can probably get some cool visuals if we take another drop of mud and peer at its contents under the microscope. If there are amphipods and forams, there will be nematodes in Cameron’s sample. If nematodes can live ~3km deep within the fracture water of South African mines, they can certainly put up with a little bit of pressure and scraps of food in the Hadal zone. So yeah, we should be able to get some pictures like this (for inspiration and general awesomeness):
I’m not done yet. We can still get more from that core, including:
- Characterizing the chemical makeup of the sediment. This can be done via methods such as stable isotope analysis, and we can ask questions such as: Can we pinpoint the original source of the organic matter in the Challenger Deep? What type of food is available for organisms down there? What does that say about conditions and species’ habitats in the deepest ocean trenches?
- Sediment geochemistry. What type of sediment is down there? Where did it come from (what continent or ocean region) and what trajectory might it have taken as it slowly sunk to the deepest depths?
All in all, Cameron’s sample will fundamentally contribute to our knowledge about some big questions in biology, such as:
Biological adaptations to life in extreme environments
Tim Shank, a deep-sea biologist at the Woods Hole Oceanographic Institution in Massachusetts, says that the waters above Challenger Deep are extremely unproductive; there is little algal life at the surface, and, therefore, less food is cycled down to deeper waters. “If it had been a trench with a productive water column, like the Kermadec Trench near New Zealand, I think he would have seen much more biology,” says Shank. However, sediment samples are certain to contain billions of microbes.
Insight into what life might be like on other planets:
The mud could contain exotic species of microbial life that may not only advance our understanding of the deep ocean but also help in the search for extraterrestrial life. For instance, scientists think Jupiter’s moon Europa could harbor a global ocean beneath its thick shell of ice—an ocean that, like Challenger Deep, would be lightless, near freezing, and home to areas of intense pressure. (See “Could Jupiter Moon Harbor Fish-Size Life?”)
So for those of you that scoffed at the botched sampling, there’s some serious scientific amazingness that awaits us in that half core of mud. | <urn:uuid:c27ab378-b23c-42df-9c5a-4aedecc4a586> | 3.546875 | 1,872 | Personal Blog | Science & Tech. | 36.186005 |
Broaden your selection:
- 4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
- A Bingo
- Rails A/B testing. One minute to install. One line to set up a new A/B test. One line to track conversion.
- A+ is a powerful and efficient programming language. It has a rich set of functions and operators, a modern GUI with many widgets and automatic synchronization of widgets and variables, asynchronous execution of functions associated with variables and events, dynamic loading of user compiled subroutines, and many other features. Execution is by a rather efficient interpreter. It is mainly used in a computationally-intensive business environment, but many critical applications written in A+ have withstood the demands of real world developers over many years. It is written in an interpreted language, so applications tend to be portable.
- ACDK is a development framework with a similar target of Microsoft's .NET or Sun's ONE platform, but instead of using Basic/C# or Java as programming language, it bases C++ as core implementation language. ACDK implements the standard library packages, including acdk::lang, acdk::lang::reflect, acdk::util, acdk::io, acdk::text (including regexpr), acdk::net, acdk::sql, acdk::xml and more, as well as technologies like flexible Allocator/Garbage Collection, Threading and Unicode. With the extensions of ACDK C++ objects are available for reflection, serialization, aspect oriented class attributes and [D]ynamic [M]ethod [I]nvocation. This DMI act as an universal object oriented call interface to connect C++ with scripting languages (Java, Perl, Tcl, Python, Lisp, Visual Basic, VBScript) and standard component technologies (CORBA, COM+).
- ACL2 is a mathematical logic and a mechanical theorem prover to help you reason in the logic (which is a subset of applicative Common Lisp). The theorem prover is an ``industrial strength version of the Boyer-Moore theorem prover, Nqthm. Users can build models of all kinds of computing systems in ACL2, just as in Nqthm, even though the formal logic is Lisp. Once you've built an ACL2 model of a system, you can run it and use ACL2 to prove theorems about the model.
- ADG: Automatic Drawing Generation
- The ADG library (Automatic Drawing Generation) is a set of functions focused on automating the drawing of mechanical parts. It is not a CAD system but a library providing a non-interactive canvas where you can put common CAD entities such as paths, xatches and quotes, to create your technical drawings. The final result can be displayed inside a GTK+ widget or exported to any cairo available format, such as PostScript and PDF documents or PNG and SVG images.
- AGFL is a parser generator for natural languages. It can cope with ambiguity, which is a must for natural languages, has a lexicon system and is quite fast. If you don't know what to think of it, think "yacc" (or "bison") without shift-reduce conflicts.
- AKFAvatar is a fancy graphical user interface for applications, where an avatar appears on the screen and tells things to the user via a speech bubble. There can also be recorded audio files, so that the user even can hear what it is saying.
With AKFAvatar you can easily write cross platform applications in Lua. Lua scripts don't even need to be compiled for the target platform. It has an interface for C programs, which can also be used for Objective-C or C++. Furthermore there are bindings for Free Pascal and GNU-Pascal.
- 'aRts' is a framework for developing modular multimedia applications. The sound server, artsd, lets multiple applications cooperatively process and output sound and music. aRts provides its filter and synthesis capabilities to other applications using the multimedia communication protocol (MCOP). The package is also capable of modular realtime synthesis. It can create sounds & music (realtime midi synthesis) using small modules like oscillators for creating waveforms, various filters, mixers, faders, etc. As of Dec 02, 2004, development on this project has been discontinued.
- A Virtual File System lets programs look inside archived or compressed files, or access remote files without recompiling the programs or changing the kernel. It currently supports floppies, tar and gzip files, zip, bzip2, ar and rar files, ftp sessions, http, webdav, rsh/rcp, ssh/scp. Quite a few other handlers are implemented with the Midnight Commander's external FS.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the page “GNU Free Documentation License”.
The copyright and license notices on this page only apply to the text on this page. Any software described in this text has its own copyright notice and license, which can usually be found in the distribution itself. | <urn:uuid:b1556d22-776f-404a-9eaf-b9ca17840615> | 2.734375 | 1,241 | Content Listing | Software Dev. | 39.178174 |
The World Climate Research Programme (WCRP) International Programme for Antarctic Buoys (IPAB), through participating research organizations in various countries, maintains a network of drifting buoys in the Antarctic sea ice zone to support a better understanding of sea ice motion, meteorology, and oceanography. The IPAB Antarctic Drifting Buoy Data archive, presently spanning the years 1995 to ... 1998, includes measurements of buoy position, atmospheric pressure, air temperature, and sea surface temperature. Data are organized by daily and three-hour averages and the raw, instantaneous, non-interpolated data values. Data were collected from buoys initially deployed in three study regions: East Antarctica; the Weddell Sea; and the Bellingshausen, Amundsen, and Ross Seas. Data are in ASCII text format and are available by ftp. Data updates will become available as data are processed and new buoys are deployed. | <urn:uuid:ad2024c4-3391-4c5f-925e-b747b0e7e4ba> | 2.96875 | 185 | Content Listing | Science & Tech. | 23.036667 |
Asteroids provide unique insights into the origin and early history of the solar system. Since asteroids are considered to be fairly pristine, studying them provides opportunities to learn more about the primordial solar system, its materials, processes and history. Since the discovery in 1801 of the first asteroid, Ceres, during the era when everyone was searching for the "missing planet", astronomers have been trying to understand what they are, where they came from, why they exist and what they can tell us about how our solar system formed and evolved.
Within the asteroid population are a number of sub-populations, the primary division is due to the locations of the asteroids. There are the Main Belt Asteroid (MBA) population that resides between the orbits of Mars and Jupiter (1.8–3.5 AU) and the Near-Earth Asteroid (NEA) population whose orbits have an aphelion ≤ 1.3 AU. Within both the MBA and NEA populations are further subdivisions (taxonomic classes) based on physical properties of the asteroids such as albedo, spectral curve and probable composition. There have been a number of taxonomic classification schemes, the most current iteration splits the asteroids into three complexes (C, S, and X) that combined are comprised of twenty-six distinct taxonomic classes.
Since the lifetimes of the NEAs are short (106–10 7 yrs), it is thought that the NEA population is and continues to be populated by the MBA population through various mechanisms like resonances and thermal forces. We have conducted a statistical comparison of the two populations as a whole, by complexes and individual taxonomic classes and found significant differences as well as similarities. On the surface, it appears that the NEA population is not representative of the MBA population. There are voids and relatively small numbers in taxonomic classes that exist in the NEA when compared to the MBA population and there are some important similarities. There are, however, biases that this analysis does not address that may explain our findings.
The asteroid taxonomy classification schemas are based on visible wavelength spectra. There are ∼2500 classified asteroids of which only a very small percentage have spectra in the infrared wavelength ranges. Here we demonstrate, using asteroid 1989 ML, the need for more asteroid spectra in the near-infrared wavelength range which contains much compositional information. We show that in the visible wavelengths spectra of several meteorites of very different types match the spectrum of 1989 ML.
Finally, we examine twenty-seven S and possible S Complex asteroid spectra. We find that most contain pyroxenes in the monoclinic form (clinopyroxene). Clinopyroxenes can contain calcium; however, there are some that do not. The cases of Ca-free clinopyroxenes are rare on Earth, but are readily found in the type 3 unequilibrated ordinary chondrites. Analyses of the asteroids and ordinary chondrites were conducted using the Modified Gaussian Model (MGM) and the Band Area Ratio. We also examined two terrestrial Ca-free clinopyroxenes using the MGM. From our results we conclude that the surfaces of S Complex asteroids are consistent with the type 3 unequilibrated ordinary chondrites. | <urn:uuid:005e2ddf-7192-4800-8e1e-eb44684810f9> | 3.90625 | 663 | Academic Writing | Science & Tech. | 28.387542 |
Ever wonder what it's like on other planets? On this Moment of Science, find out what it's like on Mercury.
Do other animals besides humans cry? Find out on this Moment of Science.
What do 6 month olds do better than 9 month olds? Find out on this Moment of Science.
Recent studies suggest a correlation between progesterone levels and paternal behavior. Learn more on this Moment of Science.
You probably already know that humans are warm-blooded, while creatures like snakes are cold-blooded. Scientists prefer the terms endothermic and ectothermic. Snakes are ectothermic–they’re dependent on their environment for heat.
There are few insects more reviled than the cockroach. Maybe we’re just jealous: cockroaches were around long before humans, and will continue to do their thing long after our species has gone the way of the woolly mammoth. | <urn:uuid:d075681d-fdc7-4d9f-9c7c-1e15dabd4c43> | 2.9375 | 187 | Content Listing | Science & Tech. | 57.529423 |
Inheritance diagram for IPython.history:
History related magics and functionality
Alternate name for %history.
Print input history (_i<n> variables), with most recent last.
%history -> print at most 40 inputs (some may be multi-line)%history n -> print at most n inputs%history n1 n2 -> print inputs between n1 and n2 (n2 not included)
Each input’s number <n> is shown, and is accessible as the automatically generated variable _i<n>. Multi-line statements are printed starting at a new line for easy copy/paste.
-n: do NOT print line numbers. This is useful if you want to get a printout of many lines which can be directly pasted into a text editor.
This feature is only available if numbered prompts are in use.
-t: (default) print the ‘translated’ history, as IPython understands it. IPython filters your input and converts it all into valid Python source before executing it (things like magics or aliases are turned into function calls, for example). With this option, you’ll see the native history instead of the user-entered version: ‘%cd /’ will be seen as ‘_ip.magic(“%cd /”)’ instead of ‘%cd /’.
-r: print the ‘raw’ history, i.e. the actual commands you typed.
-g: treat the arg as a pattern to grep for in (full) history. This includes the “shadow history” (almost all commands ever written). Use ‘%hist -g’ to show full shadow history (may be very long). In shadow history, every index nuwber starts with 0.
- -f FILENAME: instead of printing the output to the screen, redirect it to
- the given file. The file is always overwritten, though IPython asks for confirmation first if it already exists.
Repeat a command, or get command to input line for editing
Place a string version of last computation result (stored in the special ‘_’ variable) to the next input prompt. Allows you to create elaborate command lines without using copy-paste:
$ l = ["hei", "vaan"] $ "".join(l) ==> heivaan $ %rep $ heivaan_ <== cursor blinking
Place history line 45 to next input prompt. Use %hist to find out the number.
%rep 1-4 6-7 3
Repeat the specified lines immediately. Input slice syntax is the same as in %macro and %save.
Place the most recent line that has the substring “foo” to next input. (e.g. ‘svn ci -m foobar’). | <urn:uuid:e0e5584a-601c-4151-adac-02b20a241bc8> | 3.28125 | 607 | Documentation | Software Dev. | 61.576071 |
The Theory of Relativity is quite possibly the greatest modern scientific discovery of all time and yet I would venture to guess that most of us have no concept of it or at the very least fail to see how everyday life is absorbed in the major concepts of the theory. We all know it:
But what does that equation really say? It’s simply saying that the mass of a body is a measure of its energy constant, where ‘E’ stands for Energy, ‘m’ stands for Mass, and ‘c2’ represents the speed of light squared. This equation is often in physics referred to as the mass-energy equivalence concept. We wont get into the math behind it, and lets face it, most of us can’t (myself included).
Einstein’s Theory of Relativity consists of two separate theories called special and general relativity. Special relativity is an expansion on Galilean relativity, which expresses how matter moves through time and space. General relativity is an expansion to his own special relativity theory, which essentially adds gravity into the mix.
So many people ask, ‘How is this a factor in my everyday life?’ We’ll let’s take a look at some things that you deal with constantly (and some I hope we never have to deal with) that are directly related to these theories.
So time travel is pretty sweet and one day maybe we can travel forward, far in time, and experience the future. Impossible? Well, the thing is… we already have at a smaller scale. You’re doing it right now in relation to anyone that is at a lower elevation than you on Earth, though it’s a small enough measure that you and I would never be able to tell without extremely sensitive equipment. Basically what time dilation describes is that the stronger the force of gravity the slower time moves for you in relation to someone who is experiencing weaker gravity. That being said, time for you wont seem to be moving slower relative to you, just as time for the other person experiencing weaker gravity wont seem to move any faster. Now only is this mathematically proven, but we have recorded the effect in real life and it is essential to one piece of equipment we all use daily now.
GPS is a staple technology found in almost all phones and every car. We use it to help us get to places we are unfamiliar with, however if GPS satellites didn’t account for time dilation, we would never get where we needed to go. Imagine the Earth with a GPS satellite coasting in motion far in orbit around Earth. The pull of Earth’s gravity (which is quite weak in relation to other objects in space) is weaker for the satellite where as your car on Earth is closer to the Earth’s mass and thus the pull of gravity is stronger. GPS works by essentially firing a radio wave from your phone to a set of satellites that triangulate your position. Easy enough, I suppose.
This is where it gets interesting and where atomic clocks located on the satellites must be exact. Your phone sends requested signals to satellites located above you in orbit, and because they are constantly moving some may be further away from you than others. If a satellite were to be directly above you then the distance the radio waves need to travel is shorter than a satellite that is located north east of you. These radio waves travel at the speed of light (which is about 670,616,629 mph. Not bad.) However, even at this speed, the satellite directly above you has less distance to travel than the one north east of you. Once the distances of at least four of the twenty-four GPS satellites in orbit are estimated by your phone in can then pinpoint your location in three dimensions.
Now time dilation has to be accounted for because the satellites are experiencing time faster than you due to your stronger gravity, so atomic clocks are programmed to account for this small difference and therefore your location will be accurate to around 10 meters or so based on your ability to broadcast and receive signals. This is why GPS tends to have a harder time in wooded areas. If your phone cannot get an accurate idea of how far the satellite is away from you because the atomic clock on board doesn’t account for time dilation (or because your signal is being obstructed), your phone would be completely inaccurate in its guess of your position on a map. Our ability to account for time dilation is precisely why your GPS gets you (most of the time) where you need to go.
Looking Back in Time:
The speed of light is constant. The reason this is so has to do with the fact that mathematically the more mass an object has the more energy it needs to reach faster and faster speeds (remember the mass-energy equivalence?). So an object with mass would need an infinite amount of energy to reach the speed of light. That being said, the smallest mass-less light, energy, or information particles are also limited to this speed. Because light is limited to this speed as well, we know a few things.
Walk outside and look quickly at the sun (don’t stare!). The image burned onto your eyes is what the sun looked like 8 minutes ago. This is because the light that is traveling from the Sun to the Earth is traveling at the speed of light, which even at that great speed takes about eight minutes to reach us. Now do the same thing later in the evening with the moon (feel free to stare all you want). The image you are seeing in the sky is about 1.26 seconds behind. It only takes 1.26 seconds for light to travel the distance between the Earth and Moon. So imagine that the sun exploded. Even after it happened, it wouldn’t be until 8 minutes later that we saw the effects in our sky. The moon would be much quicker but still delayed that 1.26 seconds.
The speed of light expressed in Einstein’s theory allows us to measure great distances in space and so a general rule of thumb is that the further you look into space the older the image you see in the sky really is. So another example is the Helix Nebula (commonly referred to as the “eye of God”), whose image in our skies is about 700 years old. This again means that it takes light 700 Earth years to cover the distance from the nebula to Earth. To see it from Earth is to look back in time 700 years. The furthest galaxies (in our observable Universe) that we can see with our current technology show that they are a distance of about 13.3 billion light years, meaning that the earliest light first generated by that galaxy has been traveling almost the entire life span of the Universe as we know it to be at an age of about 13.7 billion years old. We are literally traveling back in time just by looking in the sky, because not even light photons can travel faster than the speed of light.
Given that light travels at a maximum speed of about 670,616,629 mph, there is a greater beast that even light cannot escape. One of the interesting things about Einstein’s theory was that the math involved ended up predicting an anomaly that was quite perplexing in what it said and meant. Even Einstein thought that despite the prediction his math made, that it more than likely would not actually exist in the cosmos. The math simply predicted that extremely compact mass would deform space-time to form what they labeled as a black hole.
The best way to imagine a black hole is to pretend that you’re floating in a rowboat in an endless body of water. We’ve all seen waterfalls and we all know that the human body has limitations, because we can only row so fast. This limitation would be the speed of light in relation to a black hole. So we paddle towards what looks like a giant whirlpool waterfall where all the water is rushing towards and falling down into. We can paddle fairly well as long as we stay far away from the event horizon. This is the point at which the force of gravity is pulling stronger than the speed at which we can row. Since nothing can travel beyond the speed of light, we cannot simply row our way out of our impending doom. Gravity is stronger and will continue to become even stronger as we fall further and further in.
What this shows is that since light has a maximum speed, even light itself cannot escape the stronger pull of gravity beyond the event horizon. Any light that crosses the event horizon of a black hole cannot escape, hence the name, black hole. The pull of gravity is so strong in fact that it distorts light around the black hole, giving the outside viewer a kind of “lensing” effect around the black hole. Light bends and distorts around the black hole. Till this day we have not physically seen a black hole in the way in which we imagine them, though we are close. Lensing is one way to know a black hole is possibly near by (possibly, because other things in space also cause this), but we have, however, seen objects that are orbiting around a black hole and how they interact and thus can identify them as well.
Our own Milky Way was discovered to contain a super-massive black hole at its center by observing star orbits over a period of 15 years. It was observed that a cluster of stars were traveling in elliptical orbits around an unidentified object at speeds that would require the sort of gravity known only to a black hole. It is now believed that black holes are a prominent feature of most, if not all, galaxies.
Many consider the Theory of Relativity one of the greatest human discoveries, and because it has been rigorously tested and proven to be accurate time and time again in both mathematical and observable experimentation, it has withstood the test of time. It not only explains our Universe and makes sense of our surroundings, but also helps to push us further in understanding even more of the unknown. It makes our everyday lives easier and explains with other collected evidence how much of our Universe operates. Scientists are still looking for the link (via string theory) as to how the theory of relativity connects back to the microscopic actions of gravity, or how to explain the physics of the very small and the very big. Maybe one day Ill try and tackle some of the more easy to understand concepts of string theory or even m-theory, but they are a whole new can of worms that require patience. One day… | <urn:uuid:edc2b192-c1b9-4948-8df8-0fb735bc11e5> | 3.015625 | 2,153 | Personal Blog | Science & Tech. | 54.001435 |
Five months ago or so, Honeywell organized a series of lectures by the Nobel laureate Sheldon Glashow at the Czech Technical University (ČVUT) in Prague.
The lecture you can watch now asked the question whether science evolves by chance or by design.
It's a sort of a fun, light, philosophically and historically loaded talk.
Maybe the number of the historical episodes will be boring for you: he could be a professional historian of science right away.
Typical Czech engineering students are listening to Glashow. ;-)
But if you like the first part, continue with Part 2 and Part 3. If you make it to the third part, there will be some examples of his point from modern physics. Around 18:00, he also talks about Gell-Mann and quarks' and string theorists' delight when they deduced that string theory predicted gravity. Glashow doesn't count it as a prediction because he had known about gravity before string theory was born. Of course, from the viewpoint of the history of science, it wasn't a (new) prediction: the chronology guarantees that. However, from the viewpoint of science and the strength and validity of its hypotheses, the fact that string theory implies general relativity is exactly as important and consequential as a prediction! The chronology is just a part of the history, social science, it was accidental, and a scientist simply can't pay attention to such things.
On the other hand, I agree that both accidental discoveries as well as "planned research" have been important and will be important.
Some other not-too-demanding physics news: Australia opened the world's fastest radio telescope.
Robert Christy, a physicist who worked on the Manhattan Project and the first one who became hostile against Edward Teller after he identified Oppenheimer as a communist, died.
An 11-year-old maľchik (=Russian boy) discovered the mammoth of the century (the best preserved one in 100 years). | <urn:uuid:a311115f-012d-4f7f-a951-b597bfb31851> | 2.9375 | 410 | Personal Blog | Science & Tech. | 47.052871 |
Expression.Power Method (Expression, Expression, MethodInfo)
Creates a BinaryExpression that represents raising a number to a power.
Assembly: System.Core (in System.Core.dll)
public static BinaryExpression Power( Expression left, Expression right, MethodInfo method )
left or right is null.
method is not null and the method it represents returns void, is not static (Shared in Visual Basic), or does not take exactly two arguments.
method is null and the exponentiation operator is not defined for left.Type and right.Type.
method is null and left.Type and/or right.Type are not Double.
The resulting BinaryExpression has the Method property set to the implementing method. The Type property is set to the type of the node. If the node is lifted, the IsLifted and IsLiftedToNull properties are both true. Otherwise, they are false. The Conversion property is null.
The following information describes the implementing method, the node type, and whether a node is lifted.
The following rules determine the implementing method for the operation:
If method is not null and it represents a non-void, static (Shared in Visual Basic) method that takes two arguments, it is the implementing method.
Otherwise, if the Type property of either left or right represents a user-defined type that overloads the exponentiation operator, the MethodInfo that represents that method is the implementing method.
Node Type and Lifted versus Non-Lifted
If left.Type and right.Type are assignable to the corresponding argument types of the implementing method, the node is not lifted. The type of the node is the return type of the implementing method.
If the following two conditions are satisfied, the node is lifted and the type of the node is the nullable type that corresponds to the return type of the implementing method:
left.Type and right.Type are both value types of which at least one is nullable and the corresponding non-nullable types are equal to the corresponding argument types of the implementing method.
The return type of the implementing method is a non-nullable value type.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers. | <urn:uuid:86e56b94-27ab-47e0-a54e-943364d476f9> | 2.9375 | 475 | Documentation | Software Dev. | 41.277691 |
Jan 19, 2001, 2:38 PM
Post #1 of 1
(From the Perl FAQ)
How do I find the week-of-the-year/day-of-the-year
How do I find the week-of-the-year/day-of-the-year?
The day of the year is in the array returned by localtime() (see localtime):
or more legibly (in 5.004 or higher):
$day_of_year = (localtime(time()));
You can find the week of the year by dividing this by 7:
$day_of_year = localtime(time())->yday;
Of course, this believes that weeks start at zero. The Date::Calc module from CPAN has a lot of date calculation functions, including day of the year, week of the year, and so on. Note that not all business consider ``week 1'' to be the same; for example, American business often consider the first week with a Monday in it to be Work Week #1, despite ISO 8601, which consider WW1 to be the frist week with a Thursday in it.
$week_of_year = int($day_of_year / 7); | <urn:uuid:af9f3503-6cea-48e0-8658-c9f6bc9a8961> | 2.9375 | 265 | Comment Section | Software Dev. | 60.978311 |
What is the height of the electron orbits an atom? (How far are the energy levels of the electron relative to the center of the atomic nucleus?)
How fast do electrons move in their orbits?
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3 months ago | <urn:uuid:5536d8e1-37ac-451a-8f68-3b5d9fa0db2d> | 2.765625 | 75 | Q&A Forum | Science & Tech. | 60.108952 |
Major Section: PROGRAMMING
(String>= str1 str2) is non-
nil if and only if the string
str2 precedes the string
str1 lexicographically or the strings
are equal. When non-
(string>= str1 str2) is the first
position (zero-based) at which the strings differ, if they differ,
and otherwise is their common length. See string>.
The guard for
string>= specifies that its arguments are strings.
String>= is a Common Lisp function. See any Common Lisp
documentation for more information. | <urn:uuid:f21634d9-a686-41dd-996c-a1120e1fab7e> | 2.921875 | 127 | Documentation | Software Dev. | 69.65592 |
I'll not make modifications to the text except for differences between C and Python.
You can find the first part of this article here: Writing a Widget Using Cairo and PyGTK 2.8
Making the clock run is as simple as starting a timer that calls a callback. However, we might also want to be able to set a different time on our clock, so we'll store the time for the clock inside the widget. We don't want to let people change the time directly, in object-orientation speak, we want to make the time variable private.
Python, in its "trust the programmer" philosophy usually use a convention (the single "_" underscore) to identify a variable as private. I implemented the public API as a property in this way:
# public access to the time member def _get_time(self): return self._time def _set_time(self, datetime): self._time = datetime self.redraw_canvas() time = property(_get_time, _set_time)
Now you can externally access the time property as if it's a simple object member.
We can use the property in the update() method which will update the clock with the new time:
def update(self): # update the time self.time = datetime.now() return True # keep running this event
Notice that this method returns a boolean value (true). Functions passed as timeout events return a boolean value. If the value is true, the event will be run again; if the value is false it will not. There is also a method that we haven't defined yet, redraw_canvas(). This method will redraw the canvas for us. From the manual page for GtkDrawingArea (our parent class), we are told to use gdk.Window.invalidate_rect(), to reexpose the canvas (and cause it to redraw). In order to make our event happen now, we should also call gdk.Window.process_all_updates(). Our redraw function looks like this:
def redraw_canvas(self): if self.window: alloc = self.get_allocation() rect = gdk.Rectangle(0, 0, alloc.width, alloc.height) self.window.invalidate_rect(rect, True) self.window.process_updates(True)
Drawing the hands requires us to think about a little geometry. For the hour hand, the hand is rotated around 30� for each hour and then a 1/2� more per minute.
So to draw the hour hand, we might do something like:
context.save() context.set_line_width(2.5 * context.get_line_width()) context.move_to(x, y) context.line_to(x + radius / 2 * math.sin( math.pi / 6 * hours + math.pi / 360 * minutes), y + radius / 2 * -math.cos( math.pi / 6 * hours + math.pi / 360 * minutes)) context.stroke() context.restore()
The minute hand and the seconds hand each rotate 6° per minute/second. The minute hand is easily implemented as:
context.move_to(x, y) context.line_to(x + radius * 0.75 * math.sin(math.pi / 30 * minutes), y + radius * 0.75 * -math.cos(math.pi / 30 * minutes)) context.stroke()
Finally, we need to set it running, in __init__() we will add our timeout function:
def __init__(self): super(EggClockFace, self).__init__() self.connect("expose_event", self.expose) # make it private self._time = None self.update() # update the clock once a second gobject.timeout_add(1000, self.update)
We're left with clock_ex4.py which you can run with:
$ python clock_ex4.py
and should look like this:
The animated GIF of the clock ticking was done with a tool called byzanz. I simply recorded 60 seconds of the clock. In order to find out the window location for byzanz-record, I added this to the main function after gtk.Widget.show_all():
rect = gdk.Rectangle() rect = window.window.get_frame_extents() print "-x %i -y %i -w %i -h %i" % (rect.x, rect.y, rect.width, rect.height)
This printed settings that I could paste onto my other command line:
$ byzanz-record -d 60 $GEOMETRY -l clock.gif
So far we've written a GObject with opaque property storage and we've used Cairo to draw our clock face. However the GTK+ widgets we commonly interact with also offer public APIs and emit signals to notify us when certain events take place. We will add a signal to say when someone is dragging the minute hand around.
Firstly we need to decide on what our signal is going to send and add this our file. We will implement a "time_changed" signal that along with the object also gives the time in hours and minutes that the clock has now been set to. If we were connecting this signal, our callback would look something like this:
def time_changed_cb(widget, hours, minutes): pass
Finally we need to register our signal in the class:
__gsignals__ = dict(time_changed=(gobject.SIGNAL_RUN_FIRST, gobject.TYPE_NONE, (gobject.TYPE_INT, gobject.TYPE_INT)))
More information on gobject.signal_new can be found in the documentation.
Next we have to implement a button_press_event handler so that we can determine when someone has actually clicked on a hand. We can override the signals for button_press_event, button_release_event and motion_notify_handler at the same time as replacing the expose_event. In __init()__:
self.connect("expose_event", self.expose) self.connect("button_press_event", self.button_press) self.connect("button_release_event", self.button_release) self.connect("motion_notify_event", self.motion_notify)
From reading the documentation for GtkDrawingArea, our parent class, you will see that button events and motion events are masked out, so we will need to set them so that we receive events for processing. We need to do this for each EggClockFace, so in __init__() we'll add:
self.add_events(gdk.BUTTON_PRESS_MASK | gdk.BUTTON_RELEASE_MASK | gdk.POINTER_MOTION_MASK)
The line formed by the bearing of the hand is infinitely thin, so we can't expect a user to be able to click on it. It would be nice to detect if the user clicked within 5 pixels of the line. To do this we require some more geometry.
We know that (sin φ, cos φ) is a point on the unit circle, that is it has magnitude 1. Thus a vector from the origin to (sin φ, cos φ) will be a unit vector, we will name it l. We will also take a vector p which is the vector from the origin to the point where the user clicked.
This would give vector components equal to:
px = event.x - widget.get_allocation().width / 2 py = widget.get_allocation().height / 2 - event.y lx = math.sin(math.pi / 30 * minutes) ly = math.cos(math.pi / 30 * minutes)
Simple reasoning will tell us that there exists a point ul where l is perpendicular to (ul – p) (which is the shortest distance between the point and the line and is what we want to measure).
We can project p onto l using the dot product such that u = p.l. The dot product can be done mathematically like so:
u = lx * px + ly * py
If u comes out to be a negative number we'll ignore it, this means that the user clicked on the opposite side of the clock to where the hand is. Finally, the magnitude of the distance can be found. If the magnitude of the distance (squared) is less then 5 pixels (squared) we can set the private member _dragging to be true (we used squared values here because we have no need to do a slow sqrt()).
if u < 0: return False d2 = math.pow(px - u * lx, 2) + math.pow(py - u * ly, 2) if d2 < 25: # 5 pixels away from the line self._dragging = True
We now need to implement handlers for the motion_notify_event and button_release_event. Both of these signal handlers share a lot of their code, so we can move it out into another method, emit_time_changed_signal(). The geometry for this method is simply the reverse of the geometry that we used to draw the hands on the clock face.
def emit_time_changed_signal(self, x, y): # decode the minute hand # normalize the coordinates around the origin x -= self.get_allocation().width / 2 y -= self.get_allocation().height / 2 # phi is a bearing from north clockwise, use the same geometry as we # did to position the minute hand originally phi = math.atan2(x, -y) if phi < 0: phi += math.pi * 2 hour = self.time.hour minute = phi * 30 / math.pi # update the offset self._minute_offset = minute - self.time.minute self.redraw_canvas() self.emit("time_changed", hour, minute)
The time_changed signal is actually sent to all listeners by emit(). You may also notice the variable _minute_offset, we use this to know how far out of phase the minute hand is with the current time. This offset has to be added to any other requests for the current time. I will leave it as an exercise to the reader to implement a similar offset for the hour hand.
After all of this our two signals handlers from above are simply:
def motion_notify(self, widget, event): if self._dragging: self.emit_time_changed_signal(event.x, event.y) def button_release(self, widget, event): if self._dragging: self._dragging = False self.emit_time_changed_signal(event.x, event.y) return False
Of course, in order to find out when our signal is emitted, we only need to connect a signal handler to the clock in main():
clock.connect("time_changed", time_changed_cb) def time_changed_cb(widget, hours, minutes): print "::time-changed - %02i:%02i" % (hours, minutes)
Putting it all together, you should have clock_ex5.py.
That's it! You now know how to implement a GObject, draw things inside that GObject, add private data, add signals and animate the object. This forms pretty much everything you need to write your own GtkWidget.
UPDATE: thanks to Johan Dahlin for the hints on __gsignals__. | <urn:uuid:991c61ab-a7c8-4839-b688-fd580365f019> | 2.859375 | 2,503 | Documentation | Software Dev. | 64.84767 |
Parthenogenesis in New Zealand Stick Insects
[Read before the 8th N.Z. Science Congress, in Auckland, May 20, 1954; reccived by the Editor, May 24, 1954.]
The phenomenon of parthenogenesis is known to occur in many species of phasmids, but it has not hitherto been recorded among the phasmids of New Zealand. Most species of the genus Clitarchus can reproduce parthenogenetically as well as sexually and both processes of reproduction apparently occur together With the exception of the species Acanthoxyla senta, found only on the Three Kings Islands, all the species of the genus Acanthoxyla reproduce parthenogenetically. Breeding experiments carried out over periods of four to six years with four species of Acanthoxyla have failed to produce any males. These are considered to represent the parthenogenetic species in which the male has been completely suppressed. The seven parthenogenetic forms of Acanthoxyla form a “parthenogenetic ring” of closely lelated but quite distinct species in which this relationship could probably be varied only by the intervention of a functioning male.
Parthenogenesis is of common occurrence amongst insects, and is known to occur in many species of Phasmids. The Indian and South European species upon which much research has been done, breed almost entirely parthenogenetically. It is not surprising, therefore, to find the phenomenon of parthenogenesis of widespread occurrence in several genera of New Zealand stick insects. My attention was first drawn to this some years ago when I commenced breeding different New Zealand species in an attempt to relate male forms to their correct females. From these experiments 1 soon learned that parthenogenesis was of frequent occurrence among species of Clitarchus and Acanthoxyla and that it also occurred in certain species of Mimarchus, but was absent or very rare in the species belonging to Argosarchus. Although these breeding experiments have satisfactorily solved the relationships of the different male and female forms of stick insects found in New Zealand, they have not completely solved the riddle of parthenogenesis, but I thought that it might be appropriate at this stage to make public what I have so far learned on this subject.
The common smooth green or brown stick insect, found all over the country, belongs to the genus Clitarchus Stal, and is known as C. hookeri (White). C. hookeri breeds both by parthenogenesis and by the normal sexual mating process. Eggs from a mated female give rise to both male and female offspring, but eggs developing parthenogenetically give rise only to females. The genus Clitarchus also contains another new species, at present undescribed, and in which no male has so far been found, neither in the field nor by breeding. A female hookeri, taken in the field and kept alive in the laboratory, produced about 200 eggs from the hatchings of which I selected six females. These females were segregated before maturity so that their offispring would be reproduced parthenogenetically. At the same time in another group six females and six males were segregated together to ensure that their offspring would develop from fertilised eggs. Each
of these series was inbred and kept going for six years, and each series produced one generation per year. At the end of this period the mated series was as vigorous as ever, but in the seventh year all the parthenogenetic females but one died before maturity. The one that survived was well below normal size and laid only eleven eggs. These eggs were also smaller than normal and none of them hate led. During the six years of parthenogenetic breeding there was always a very he ivy mortality of nymphs during the second instar which, so far as I could ascertain by feeding experiments, was not due to dietary or water deficiencies. At no time during this parthenogenetic breeding was a recognisable male produced. The possibility of males having been produced but dying before they could be recognised cannot be discounted, though I think that it is extremely unlikely. A further series of hookeri which was bred parthenogenetically for four years and in which the originating female came from Cuvier Island gave very similar results. The average length had diminished from 8.3 cms. to 6.6 cms. over this period, though in the first parthenogenetic generation the average length was slightly greater than normal, a phenomenon I was to notice in conducting similar experiments with species of Acanthoxyla In both these parthenogenetic series of C. hookeri, with the exception of the length of the body, the morphological characteristics of the species did not vary to any great extent. For example, the spines on the fore femora varied between five and seven, a percentage of variation which is much less than that found often between odd specimens taken at random in the field. This is in approximate agreement with Weismann's views on parthenogenesis (1893), but contrary to those of Warren (1899) dealing with parthenogenesis in Daphnia, and of Ling Roth (1920) dealing with the phasmid Carausius morosus.
It would appear from these observations that the species C. hookeri, though it can reproduce parthenogenetically, cannot continue to perpetuate itself indefinitely by this means, at any rate while kept in captivity. This is in strange contrast to the undescribed species of Clitarchus, which apparently reproduces only by parthenogenesis.
The genus Acanthoxyla was set up in 1944 by Uvarov for the species previously known as Acanthoderus prasinus Westwood and its related forms. This genus includes all those spiny or tuberculated species in which the operculum of the female it provided with a basal spine or large tubercle. Besides the species prasina the genus also includes forms described under the names geisovii (Kaup), suteri (Hutton), senta Salmon and the four new forms, A. inermis, A. intermedia, A. huttoni and A. speciosa described elsewhere in this volume. Of all these species the only one in which a male is known is A. senta, which occurs only on the Three Kings Islands. The remaining species are found practically throughout New Zealand, but none of them occur on the Three Kings In all of them females only are known, and breeding experiments so far conducted have failed to produce any males. According to Hutton the species geisovii was described by Kaup from a male specimen; how Hutton came to this conclusion I do not know, as Kaup does not mention the insect's sex in his description. Intensive collection from all over the country and breeding experiments in which several thousands of specimens have been handled have both failed to yield a single male specimen of the form we call geisovii. In these breeding experiments four species of Acanthoxyla have been tried, including geisovii, prasina and two of the new species. All these were kept going for periods of four years, and in
all but one the species continued to breed true to form with small but quite noticeable variation. In the aberrant specimens-the number and positions of spines and tubercles did vary appreciably from generation to generation or between individuals of the same generation. This variation, however, was never of sufficient magnitude to constitute a new species. It is curious that in these Phasmids the first generation in captivity usually shows a small increase in length over the length of the originating female With geisovii in the fourth year there was also a noticeable diminution in the length of the body and in the number of eggs laid. The other three species still appeared to be quite vigorous, but the experiments had to be stopped at this stage for unexpected reasons. It would appear, therefore, that in the genus Acanthoxyla we have seven parthenogenetic species each of winch breeds true to form and can always be recognised as distinct. When I first began collecting these Acanthoxyla species I at first thought that Hutton had been wrong in recognising four distinct species. They all appeared to me to be but variations of one common type, but the results obtained from breeding experiments confirmed that these forms were, indeed, distinct species. As a result, I now recognise eight species of Acanthoxyla, all but one of which reproduce only by parthenogenesis.
Among insects exhibiting agamic reproduction it has been found that the somatic cells are diploid in some, and haploid in others. In haploid parthenogenesis males only are produced (eg., hive bees) whereas in diploid parthenogenesis both males and females can be produced (e.g, aphids). I have not made any cytological investigations into the condition of the body cells of any of the New Zealand phasmids but I should expect them to be in the diploid condition, in which case parthenogenetic development could normally be expected to produce males at regular though perhaps lengthy intervals. In all experiments I conducted the parthenogenesis exhibited by the species of Chtarchus and Acanthoxyla prdouced females only, and is, therefore, somewhat unusual. In the species C. hookeri parthenogenetic reproduction appeared to be quite sporadic and did not alternate with regular periods of sexual reproduction, and I consider that the phenomenon is not so highly developed in this species as in the species of Acanthoxyla. C. hookeri apparently resorts to parthenogenesis only in the absence of males. These results are in close agreement with what has so far been discovered in connection with parthenogenesis in the European phasmids. Bacillus (gallicus and Bacillus rossii, as well as with the Indian species Carausius, morosus. Various workers on this problem of parthenogenesis in phasmids have shown that the phenomenon is almost universal amongst these insects and that in the entirely parthenogenetic forms such as B. gallicus, B. rossii and C. morosus. males are very rarely produced. When they do occur these males are generally gynandromorphs. Pure functional males capable of a successful copulation are extremely rare.
It would seem to me that, in these parthenogenetic phasmids, we see an evolutionary trend which tends to dispense with the male form and which ultimately gives rise to a series of parthenogenetic species that continually breed true. We see the process started but not complete in C. hookeri, while in the seven New Zealand mainland species of Acanthoxyla we see it completed. In Acanthoxyla I regard it as forming what I would term a “parthenogenetic ring” of closely linked or related species Quite possibly these species first arose as variations from normal sexual matings which were immediately capable of parthenogenetic
reproduction. If males should ever appear and, if they were functional, I should expect the progeny from a mating to produce variations equivalent to the species of the parthenogenetic ring. On the other hand, if males are entirely suppressed then we should expect these species to be fixed within certain limits and incapable of any great morphological variation from their norms, and this appears to be the case in these New Zealand species.
This continual variation round a norm can be depicted as a circle or ellipse. If the variations of these seven parthenogenetic species are plotted around the circle (1–7) we obtain a diagram as shown in Fig. 1, in which each species varies on either side of the axes AA1, BB1, etc. As each species varies irregularly, it cannot be represented by a circle, but plots, instead, an elliptical figure and the inward limits of these seven figures subtend a further circle A-G, which should demarcate the limits of variation of the originating form. In the case of Acanthoxyla, this originating form from which the parthenogenetic species presumably arose, gives us a concept of the characters of the genus. This diagrammatic concept of variation might be applied to other groups of variant species, not necessarily parthenogenetic, with equally interesting results. | <urn:uuid:18c1a278-17d8-4b3c-b590-ba12f1601f0b> | 2.921875 | 2,542 | Academic Writing | Science & Tech. | 31.636829 |
Thunderstorms occur frequently during the months of June to November. This is because this is the period referred to as the Hurricane Season, where major flooding and disasters occur to homes, businesses, buildings, infrastructure and livestock.
A thunderstorm is defined by the Merriam Webster Dictionary as “a storm accompanied by lightning and thunder.” Such a storm can be very severe. When it reaches this state of severity, thunderstorms usually have hail, very gustily winds and tornados.
For a thunderstorm to form it requires moisture, rising air which is unstable and a lifting mechanism. The first stage of a thunderstorm is observed by a cumulus cloud being pushed up by rising air. The tipping point is observed when the rising air continues to feed the storm and then precipitation is released and rain begins. These storms may have black or dark green color in appearance.
There are four types of thunderstorms and they are as follows:
A single cell thunderstorm- Such a storm is defined as “an air mass that contains up and down drafts in connective loops, moves and reacts as a single entity, and functions as the smallest unit of a storm-producing system.” This type of storm usually last around thirty minutes and are not severe. Also, they are different to predict because they occur at random times and locations.
A multicell cluster is defined as “a group of cells moving as one, with each having its own life cycle.” This type of thunderstorm is very common and can produce hail, flash floods and tornados.
A multicell line storm is defined as “a long line of storms with a continuous well-developed gust front.
A super cell is the most organized among the types of thunderstorms. With this type of storm, there is little or no precipitation fall back down, making the storm survive for a long period of time. | <urn:uuid:646a6177-e489-47b6-8c19-a073051af62c> | 4.09375 | 388 | Knowledge Article | Science & Tech. | 48.020226 |
Let’s go back and consider a linear map . Remember that we defined its rank to be the dimension of its image. Let’s consider this a little more closely.
Any vector in the image of can be written as for some vector . If we pick a basis of , then we can write . Thus the vectors span the image of . And thus they contain a basis for the image.
More specifically, we can get a basis for the image by throwing out some of these vectors until those that remain are linearly independent. The number that remain must be the dimension of the image — the rank — and so must be independent of which vectors we throw out. Looking back at the maximality property of a basis, we can state a new characterization of the rank: it is the cardinality of the largest linearly independent subset of .
Now let’s consider in particular a linear transformation . Remember that these spaces of column vectors come with built-in bases and (respectively), and we have a matrix . For each index , then, we have the column vector
appearing as a column in the matrix .
So what is the rank of ? It’s the maximum number of linearly independent columns in the matrix of . This quantity we will call the “column rank” of the matrix. | <urn:uuid:a1848edc-3360-42a4-b7b5-4eeaece7ad9d> | 3.53125 | 271 | Personal Blog | Science & Tech. | 58.287841 |
Lichens in Australia
The first published report of an Australian lichen appeared in 1806 and since then numerous species have been reported for Australia. Currently over 3000 species are said to occur in Australia and a little over a third are not known elsewhere. Amongst those 3000 plus there are still undoubtedly some invalid records. Such invalid records can arise from a variety of causes and the following paragraph will give some examples.
Specimens collected in Australia have been the basis for the descriptions of many species. At times what has later been shown to be the one species has been described as new several times under a variety of names. Here is an example. In 1876 James Stirton of Glasgow described the new species Graphis mucronata (photo below). In 1882 Jean Müller of Geneva described four new species (Phaeographis australiensis, Phaeographis cinerascens, Phaeographis inscripta, Phaeographis subcompulsa) and in the same year Charles Knight of New Zealand described the new species Graphis aulacothecia. All these species were based on material collected in New South Wales. Recent study has shown that all these species are identical and Stirton's name is the one used for it. The species Letrouitia subvulpina, originally described from Cuba, was once thought to occur in Queensland. This was based on the assumed equivalence of that species with Letrouitia sayeri, the original description of which was based on material collected from Queensland and was published after that of Letrouitia subvulpina. Chemical and microscopic analysis has shown the two are best considered as separate, though superficially similar, species. The species Trypethelium exiguellum was described in 1899, based on a specimen collected on Thursday Island in Queensland, and for a century was not recorded from anywhere else. In 1992 this seemingly Australian endemic lichen was shown to be a non-lichenized fungus. Lepraria incana, widespread in the world, had been thought to occur in Tasmania, Victoria and Western Australia but a recent study found no evidence of the species in Australia. Australian specimens named as Lepraria incana were found to be misidentifications of Lepraria lobificans or Lepraria yunnaniana. Lecanora subpiniperda and Lecanora subpurpurea were originally described in 1882 and 1899 respectively, based on material collected in New South Wales and Queensland, respectively. The original species descriptions were very brief and the original (or type) specimens can no longer be found. It is therefore impossible to re-examine the type specimens with modern methods to see if or how those two species differ from others in the genus. Those two Lecanora species are therefore doubtful species.
The previous paragraph gave examples of some of the erroneous Australian species records that have been detected and removed. It is easy to see that erroneous records have biogeographic implications. There are still various lichen groups in need of critical study in Australia and future studies of such groups will undoubtedly reveal more dubious species records. Nevertheless, even allowing for such undetected errors, there are still a great many species well studied and validly recorded for Australia, so making some biogeographical analysis possible. With such a wide range of lichens found in Australia it's not surprising that they are geographically distributed in a variety of ways. The DISTRIBUTION PATTERNS page gave examples of distribution patterns, a number of which included Australia. The following two pages give some more biogeographical information about the lichens found in Australia:
AUSTRALIA AND ELSEWHERE – This page gives some examples of lichens found in Australia and other parts of the world.
ENDEMIC TO AUSTRALIA – Deals with lichens known only from Australia.
The remainder of this page will be devoted to a couple of examples, the first involving a single species and the second the summary of a single field trip. The first shows that it can take a considerable time to build up a good picture of a particular species' distribution while the second shows that Australia still offers great scope for lichen exploration, even in non-remote areas. Both show that there are still likely to be many changes in ideas about the biogeography of Australian lichens.
Buellia levieri is a good example of a species that, for many years, appears to be confined to a very small area of Australia but is then shown to be far more widespread. This species was described in 1911 by Antonio Jatta, of Italy, based on material collected near Geeveston in Tasmania by William Weymouth. There is no record of habitat information with the specimen, but it seems likely that it was collected in a cool temperate rainforest. A second collection, from cool temperate rainforest in a different area, was made in 1983 by the Tasmanian lichenologist Gintaras Kantvilas. The authors of a paper published in 1994 noted that the species was then still known only from those two collections and wrote:
That only two collections of this species are known, despite extensive recent collecting activity in Tasmania, particularly in wet forests, suggests it is extremely rare.
In 2007 it was reported from Western Australia and by the end of 2009 it had been reported also from New South Wales, Queensland, Victoria and distant South America. Despite now being known from widespread parts of Australia it is still rare and known from very few locations as you can see from the accompanying map. However the currently known distribution suggests that the species is likely to be found at other places as well. Moreover, it appears to tolerate a variety of habitats since it was collected in Western Australian from a dead Acacia in remnant Acacia-Eucalypt woodland along a seasonal creek, quite different to the cool temperate rainforest of Tasmania.
A western fortnight
There are still many areas of Australia that are largely unexplored from a lichenological perspective. There are diverse habitats (and micro-habitats) in the many areas that are accessible only by rough roads, especially when you look at the large part of Australia that is more than say a hundred or so kilometres from the nearest coast. However, it is not necessary to go to remote areas to make interesting finds.
During April-May of 2004 the Australian lichenologist Jack Elix and two fellow cryptogamists spent a fortnight collecting lichens, bryophytes and fungi in south-west Western Australia, predominantly in non-coastal areas, and the red dots on the accompanying map show the collecting sites. The blue cross to the lower left indicates Perth. The blue dots indicate Geraldton (north of Perth) and Kalgoorlie (to the east). The area covered is not remote from major towns or cities, most of the sites were accessible by all-weather roads and the fortnight produced many interesting collections. With regard to the lichens many collections were of species already known to occur in Western Australia but of these a good proportion were collected from areas where they had not been recorded previously. There were also specimens of lichens already known from other parts of Australia (and perhaps overseas as well) but not yet from Western Australia. The following is a list of those species as well as the other places where the species had been found, first the Australian states or territories and then, after a dash, any overseas countries or regions. Where a species is known only from Australia I give, in brackets, the year in which the first description of the species was published.
The fieldwork also yielded specimens of two species, previously known from outside Australia, but not yet found in Australia - Diploschistes conceptionis (known from Chile and Uruguay) and Xanthoparmelia applicata (known from South Africa).
Finally, the following new species (and one new subspecies) have been described, based on specimens collected during that fortnight: Buellia psoromica, Diploschistes elixii, Buellia xanthonica, Hypocenomyce isidiosa, Maronina hesperia, Parmeliopsis chlorolecanorica , Pertusaria subarida, Thysanothecium hookeri subsp. xanthonicum and Xanthoparmelia baeomycesica.
The distributional information given for any species listed above reflects the state of knowledge on the eve of the publication of that species' discovery in Western Australia. For example, the Western Australian find of Buellia substellulans was published in 2006 and until then the species had been known only from Queensland and New South Wales, and in both those states since 1886. It took 120 years to expand its known distribution - and then considerably. The paper that published the Western Australian find also reported collections from the ACT, the Northern Territory and Tasmania, so giving this species a wide, though still patchy, distribution in Australia, as shown in the accompanying map. There are other species listed above which are also now known from other places but I haven't given the currently known distribution for each. The aim of the above is simply to show that a fortnight's concentrated searching in a rather small, non-remote area of Australia is capable of yielding an impressive addition to knowledge of the country's lichens. Such discoveries are not confined to Western Australia and, since 2004, comparable results have resulted from concentrated field work over similar periods in various other non-remote areas of Australia.
Lichen biogeography pages on this website | <urn:uuid:e61a6bb8-832b-481b-8575-316402770cee> | 3.515625 | 1,955 | Knowledge Article | Science & Tech. | 27.81345 |
Magny et al. utilizing advanced scientific techniques, reconstructed 1,000 years of past summer (July) temperatures for the Swiss Jura Mountains region. Unequivocally, they found that July temperatures during the Medieval Period were significantly warmer than modern summer temps.
"Working at Lake Joux in the Swiss Jura Mountains...employed a multi-proxy approach with pollen and lake-level data to develop a 1000-year history of the mean temperature of the warmest month of the year (MTWA), which was July...based on the Modern Analogue Technique. This work revealed what they describe as an "MWP between ca. AD 1100 and 1320," during which time the MTWA at Joux Lake exceeded that of the 1961-1990 reference period by fully 2.0°C....Thus, it would appear that the peak warmth of the MWP at Lake Joux exceeded that of the CWP at that location by something on the order of 0.4-1.0°C." [Michel Magnya, Odile Peyrona, Emilie Gauthiera, Boris Vannièrea, Laurent Milleta, Bruno Vermot-Desroches 2011: Quaternary Research] | <urn:uuid:bbce9d43-37d2-4487-9315-9f58b9d709c0> | 3.453125 | 250 | Truncated | Science & Tech. | 62.636842 |
in another class i used:
CoffeeCup original = new CoffeeCup();
original.add(75); // Original now contains 75 ml of coffee
CoffeeCup copy = (CoffeeCup) original.clone();
Now i got exact copy of CoffeeCup.
my question is: how the application is creating an subclass object(CoffeeCup) when I call super.clone().
As per my understanding if we call super.clone() that means we are calling Object.clone() -- if that is the case how it is creating the object of sub class?
Is there any underlying implementation that Object class uses for creating the subclass object?
All you need to know is that Object.clone() will simply create a new object of the exact same type (so in your case CoffeeCup) and copies all fields by using simple assignments. For example:
Line 11 could be replaced with the following:
There are three big differences though:
1) when you use Object.clone(), a sub class can call super.clone() and it will not return an instance of Test but an instance of that sub class.
2) Object.clone() does not call a constructor so no constructor code is executed
3) Object.clone() can also copy final fields | <urn:uuid:0dada657-197b-47c7-9020-2e8653ef6c14> | 3.484375 | 272 | Q&A Forum | Software Dev. | 60.264375 |
September 23 marked first day of autumn north of the Equator and the first day of spring to the south.
Day and night were approximately of equal length worldwide at that time, and will be again next March 20.
The animation of Earth’s seasons to the right takes us, one day at a time, from September 19, 2010 to September 19, 2011 with images from Europe’s Meteosat-9 satellite.
Africa comprises most of the right part of the image, with Europe dimly visible in the upper right.
Each image was taken at 6 a.m. GMT, meaning it was near sunrise at those times over western Europe and about midnight in the eastern United States.
On March 20 and September 20, the terminator, or sunrise in this instance, is a straight north-south line with the sun shining directly above the equator.
On December 21, the sun resides directly over the Tropic of Capricorn when viewed from the ground, and sunlight spreads more widely over of the Southern Hemisphere. On June 21, the sun sits above the Tropic of Cancer, spreading more sunlight in the north.
Of course, it is not the sun that is moving north or south through the seasons, but a change in the orientation and angles between the Earth and the sun.
The axis of the Earth is tilted 23.5 degrees relative to the sun. The axis is tilted away from the Sun at the December solstice and toward the Sun at the June solstice, spreading more and less light on each hemisphere.
At the equinoxes, the tilt is at a right angle to the sun and the light is spread evenly.
Full story and images: NASA | <urn:uuid:0d6036f1-ae48-44dd-bea0-e411f4f607c7> | 3.8125 | 351 | Knowledge Article | Science & Tech. | 62.802878 |
Helping Streams Help Themselves, Naturally
The sights and sounds of a stream running through your backyard or your favorite neighborhood park can be a soothing antidote to the busy pace of modern life. But when U.S. Environmental Protection Agency scientists Paul Mayer and Elise Striz look at a creek bed, they notice something that nature hadn’t intended. They observe the negative effects of water running off the paved surfaces of the urban landscape.
“Water runoff is changing the flow of many streams,” says Paul Mayer, Ecologist, U.S. EPA Groundwater and Ecosystem Restoration Division, or GWERD. “Rapid runoff of rain from pavement causes stream banks to erode and forces streams to move laterally in ways that are impacting people’s homes, exposing water and sewer lines, and negatively impacting both ground and surface water quality.”
The shifting streams are a problem for municipalities like the Baltimore County Department of Environmental Protection and Resource Management, which is working collaboratively with Mayer and his colleagues at GWERD. Not only are the streams encroaching on private property and jeopardizing the urban infrastructure, the water runoff functions as a delivery system for excess nitrogen into the stream bed.
A little bit of nitrogen is necessary for the growth of all living things, but too much nitrogen can be bad for humans and the environment. Too much nitrogen in drinking water can negatively affect human health and too much nitrogen in streams can impact the ecological health of nearby watersheds and estuaries.
“The nitrogen is coming from many sources,” says Elise Striz, Hydrologist, also at GWERD. She says those sources include “excess fertilizer runoff, animal wastes, sewer lines, and even the byproduct of fossil fuel combustion from your automobile’s exhaust.”
The solution to excess nitrogen may well lie in the same method used to protect the streams from erosion – stream restoration.
“It is an engineered approach to land management that redirects the flow of the stream,” says Mayer. “By reconstructing the natural twists, turns and bumps of the stream, and re-establishing plant communities along the stream banks, stream restoration may not only address the land management problems but also improve water quality at the same time.”
Mayer and Striz have been testing this theory in a real-world experiment in an urban stream named Minebank Run in Towson, Maryland, outside of Baltimore. Minebank Run had become degraded in recent years, suffering from erosion, sediment buildup, and the loss of plants and trees along the stream banks. The belief is that by restoring the stream, scientists will be able to simultaneously recreate the conditions necessary for natural nitrogen removal from the stream. The result would be a cost-effective, sustainable method for keeping streams vibrant, which in turn aids the health of their plant, animal and human neighbors as well as downstream waterways, such as the Chesapeake Bay.
“Naturally existing bacteria actually transform the nitrogen and can reduce the nitrogen level in the water in a dramatic way,” says Mayer. “So, the goal is to create a healthy stream environment within which these natural bacteria can thrive.”
In order to test the effectiveness of this natural nitrogen removal, Mayer has been comparing nitrogen levels in Minebank Run from before and after its restoration. The early results have been impressive. Mayer says the natural features of the stream bed have been greatly improved since restoration. There is far less erosion of the stream, more plant life growing on the stream banks and, as anticipated, excess nitrogen is naturally being removed from the stream and the ground water beneath it.
In short: by restoring the stream bed back to a more natural state, the stream itself can provide cleaner water for the plants, animals, and humans that rely on the stream. More study is certainly needed. But you can be sure that Mayer, Striz and their colleagues are doing just that, keeping their eyes and ears open. | <urn:uuid:216863e1-5d0e-48c7-b592-9334ce3ad29e> | 3.734375 | 818 | Knowledge Article | Science & Tech. | 38.667686 |
The Basic Linear Algebra Subprograms (blas) define a set of fundamental operations on vectors and matrices which can be used to create optimized higher-level linear algebra functionality.
The library provides a low-level layer which corresponds directly to the C-language blas standard, referred to here as “cblas”, and a higher-level interface for operations on GSL vectors and matrices. Users who are interested in simple operations on GSL vector and matrix objects should use the high-level layer described in this chapter. The functions are declared in the file gsl_blas.h and should satisfy the needs of most users.
Note that GSL matrices are implemented using dense-storage so the interface only includes the corresponding dense-storage blas functions. The full blas functionality for band-format and packed-format matrices is available through the low-level cblas interface. Similarly, GSL vectors are restricted to positive strides, whereas the low-level cblas interface supports negative strides as specified in the blas standard.1
The interface for the
gsl_cblas layer is specified in the file
gsl_cblas.h. This interface corresponds to the blas Technical
Forum's standard for the C interface to legacy blas
implementations. Users who have access to other conforming cblas
implementations can use these in place of the version provided by the
library. Note that users who have only a Fortran blas library can
use a cblas conformant wrapper to convert it into a cblas
library. A reference cblas wrapper for legacy Fortran
implementations exists as part of the cblas standard and can
be obtained from Netlib. The complete set of cblas functions is
listed in an appendix (see GSL CBLAS Library).
There are three levels of blas operations,
Each routine has a name which specifies the operation, the type of matrices involved and their precisions. Some of the most common operations and their names are given below,
The types of matrices are,
Each operation is defined for four precisions,
Thus, for example, the name sgemm stands for “single-precision general matrix-matrix multiply” and zgemm stands for “double-precision complex matrix-matrix multiply”.
Note that the vector and matrix arguments to BLAS functions must not be aliased, as the results are undefined when the underlying arrays overlap (see Aliasing of arrays).
In the low-level cblas interface, a negative stride accesses the vector elements in reverse order, i.e. the i-th element is given by (N-i)*|incx| for incx < 0. | <urn:uuid:e363db3a-776d-4a6f-9d52-27799dc33e1f> | 2.84375 | 583 | Documentation | Software Dev. | 37.18211 |
The Global Climate at a Glance (GCAG) web application can be used to retrieve monthly and annual global temperature anomaly maps that date back to 1880. Users can also create timeseries for locations around the globe by selecting a point on the map. The interactive interface allows users to adjust the vertical and horizontal axes of the timeseries plots to view selected range of months or years of data or to view the entire period of record.
The maps are created using land surface temperature anomalies from the Global Historical Climatology Network (GHCN) data and sea surface temperature anomalies from the International Comprehensive Ocean-Atmosphere Data Set (ICOADS). These two datasets are blended into a single product to produce the combined global land and ocean temperature anomalies. The temperature anomalies are calculated with respect to the 1971-2000 base period and are averaged over 5 degree by 5 degree grid boxes. These gridded temperature anomalies are mapped by GCAG. Additional information on the dataset can be found here: Global Temperature Anomalies FAQ Page.
The data files used by the GCAG web application can be found here
*Adobe Flash Player is needed to launch GCAG. Get the latest version of Adobe Flash Player. | <urn:uuid:8a4ea970-b54c-4f1a-86d1-7849cda21dd1> | 3.125 | 243 | Knowledge Article | Science & Tech. | 24.251802 |
Update: On 16 October, NASA released an image of a faint ejecta plume observed by the LCROSS shepherding spacecraft. See Elusive lunar plume caught on camera after all
In the final minutes of its plunge toward the moon, NASA's LCROSS spacecraft spotted the brief infrared flash of a rocket booster hitting the lunar surface just ahead of it – and it even saw heat from the crater formed by the impact. But scientists remain puzzled about why the event did not seem to generate a visible plume of debris as expected.
As hundreds of telescopes and observers watched, the highly publicised NASA mission to search for water on the moon reached its grand finale at 0431 PDT (1131 GMT) with a pair of high-speed crashes into a lunar crater named Cabeus.
During the crucial moments at NASA's Ames Research Center in Moffett Field, California, scientists and engineers with LCROSS (Lunar Crater Observation and Sensing Satellite) peered in silent concentration as successive images of the crater grew larger on their screens.
Nearby, some 500 bleary-eyed visitors that had gathered overnight outside mission control were watching the same pictures on a giant outdoor screen.
Yet, immediately after the scheduled impact time, there was no obvious sign of the spectacular explosion that many were expecting. "Impacting into the moon is an unpredictable business at best," Anthony Colaprete, principal investigator for LCROSS, said in a post-impact briefing.
Colaprete did not offer definitive word as to why the visual camera apparently did not detect the event but added there were interesting changes in spectroscopic data taken by the spacecraft that might have been produced by a debris cloud. "I'm not convinced that the ejecta is not in the data yet," he said.
A worst-case scenario would have occurred if the rocket hit bedrock rather than loose, gravelly soil. In that case, the debris plume might not have reached the minimum 1.5-kilometre altitude needed to catch the sunlight and be seen by LCROSS.
Because of the angle of the crater, the plume would have needed to rise to 2.5 to 3 km in order to be seen by telescopes on Earth. A 10-km-high plume was expected.
The impact was monitored by the Hubble Space Telescope, which has not yet delivered its data. Several major observatories were also watching for signs of impact, including the Keck and Canada-France-Hawaii telescopes on Mauna Kea, neither of which saw a plume. One positive report came from Kitt Peak Observatory in Arizona, where a flash of visible light revealing the presence of sodium was recorded during the impact.
"I think we're all a little bit disappointed that we didn't see anything," David Morrison, director of NASA's Lunar Science Institute, told New Scientist.
Neither here nor there
Regardless of its ultimate scientific return, today's outcome will likely go down as one of the more bemusing episodes in NASA's long history of lunar missions. While the spacecraft appeared to be working as expected and in contact with mission controllers, it clearly did not deliver the views that scientists and spectators were hoping for.
Unlike a catastrophic failure, such as Mars Polar Lander in 1999, or a euphoric success, such as the spectacular 2005 collision of the Deep Impact mission with Comet Tempel 1, the non-detection seemed to leave officials unsure of how to react.
The big question that planetary scientists hope will be answered is: are there significant quantities of water ice on the moon? Last month, water was discovered in the lunar soil, but the amounts detected were relatively small.
A long standing mystery is whether dark craters such as Cabeus could act as cold traps, capturing water molecules that are liberated when comets strike the moon. Data from the Lunar Prospector mission, which flew in the late 1990s, indicate high concentrations of hydrogen in Cabeus. The hydrogen could belong to water ice mixed in with the rock and soil in the crater's depths.
LCROSS was designed to look for the signature of water and other molecules as it flew into the debris plume of the rocket impact. It should also have executed a sideways turn one minute prior to its own impact to see the molecular constituents of the impact backlit by the sun.
Without a plume to study, scientists will have less of a handle on the question but Colaprete says the spectroscopic data may be enough to spy the constituents of water. "It will probably take two weeks to get a yes or no answer on water," said Michael Bicay, director of science at Ames.
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Fri Oct 09 13:48:40 BST 2009 by Dave
Commentary I heard indicated that it would take several days to calibrate the data returned. So we may have something, we just do not know yet.
Sat Oct 10 09:22:31 BST 2009 by Think Again
Would this be like the invisible moon landings?
Anyway, maybe they just hit the side of the crater, and so the impact chucked the debris downwards, not upward where the sensors on the orbiter could pick it up.
Wish they had had the brains to stick a flashlight and camera on the impactor so we could see how it impacted.
Anyway, now that the moon does not show signs of huge amounts of water, we can concentrate our efforts on landing on asteroids which is really important too.
Sat Oct 10 17:13:19 BST 2009 by Agent420
They did have a flashlight on it but did not use the bunny's batteries and they went dead on the way there.
Mon Oct 12 07:27:14 BST 2009 by Dave
And for the really great challenge, try Ceres and the water located there. Gravitationally, the delta-v is a big factor. But it has the potential to be the gas station for the Solar System.
Robert Farquhat reminds us that gravity wells are a cul-de-sac to be avoided:
(long URL - click here)
Tue Oct 13 06:53:47 BST 2009 by Slobodan
That is the main reason why we need human missions in space, despite many opinions that robots are more suitable and cheaper. Robotic missions simply are not smart enough yet to handle various unknown circumstances and environments. An astronaut landing on the Moon's south pole with proper equipment would offer an answer about water presence there within the minutes or hours, without any doubt. Robots, if faced with something unpredicted, or unknown simply fail the mission goals, leaving a bitter taste in the mouths of mission control and scientists waiting for the results.
Never send a robot to do the man's job!
Tue Oct 13 07:19:46 BST 2009 by danielle grandhomme
I suppose there is no oxygen on the moon...am I wrong?
Well as I know when there is no oxygen, there is no ignition...
so, how did the module landed on moon in 1969 re-start from there to earth, as the gas could not be lighted?
Why did we need, now, to crash a module to get few datas of particles
of SOIL as there have been several moon missions
Substantially...have we really been on the moon?
I guess not.
Everest has been thousands times climbed by anyone, and thus littered with plastic bags... why not the moon?
There is a great wave of reactions to this crash, because now we are able to really watch what it is going on, live, and with no possible fake, for anyone can make false images and videos, and thus anyone can recognize fake!
NASA was under exam.
And showed its weird face to all the world, now aware.
There is deception, as I see, and anger or resignation
I have no resignation.
Tue Oct 13 10:03:43 BST 2009 by Toby
Yay! Another conspiracy nutjob. You're absolutely right, but we can go further, let's say man has never been to France either. I know there's evidence, but let's just ignore it. I also don't believe in the existence of chickens. And it's time we exposed the lie started by the CIA that humans need oxygen.
Seriously danielle, if you have such a distrust of science, why spend your time visiting a science website?
Am I Wrong, Or. . .
Fri Oct 09 13:54:16 BST 2009 by Jamie Jones
Would a very small 'plume' indicate the soil is being held together by something? I mean... unsettle dry dust, and you get a lot of that dust rising. Unsettle moist dust and you don't get a lot of anything.
Am I Wrong, Or. . .
Fri Oct 09 15:23:16 BST 2009 by Will
Mmmm, you're wrong. This would be some kind of lunar "mud". To be moist, it would have to be bound with liquid water. The temperature in these craters is as near to absolute zero as makes no difference for this purpose. The other stories referring to water in the soil don't literally mean liquid water. They're referring to individual hydroxyl or water molecules.
Am I Wrong, Or. . .
Fri Oct 09 18:11:38 BST 2009 by nicholasjh
True, but what effect would hard ice have? Maybe the concentrations are higher then they even thought.
Am I Wrong, Or. . .
Fri Oct 09 21:16:55 BST 2009 by Chris W
I did come accross something a while back where they were finding lunar soil to be stickier than expected and some have postulated that it has a static charge. I wonder if this could have anything to do with it.
Fri Oct 09 14:02:58 BST 2009 by Stricka012
Maybe the craters are deeper than they thought, or the material found there is denser than they were expecting.
Fri Oct 09 14:38:00 BST 2009 by Jamie Jones
Maybe it's stuck at the bottom of a well.
Fri Oct 09 17:41:25 BST 2009 by noses
You just nade my day. Literally! Its so bad that it's actually insanely good
Fri Oct 09 22:23:00 BST 2009 by jo
if there is no gravity on the moon, there would be no equal and opposite force to the rocket crashing into it. So there would be no upward explosion.
All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.
If you are having a technical problem posting a comment, please contact technical support. | <urn:uuid:3d55acfc-9c00-4b24-af9a-7713e180542f> | 3.546875 | 2,307 | Comment Section | Science & Tech. | 62.924365 |
Huntington is the science director for Pew's Arctic Program.
For the oil and gas industry, the Arctic Ocean is the final frontier. Beneath the ocean floor lies an estimated 90 billion barrels of recoverable oil - about 13 per cent of the global total. As the sea ice retreats and traditional sources of hydrocarbons dwindle, the pressure to drill is becoming irresistible.
It now seems inevitable that this harsh environment will be opened up to oil and gas production, which poses a big question: how much scientific research is "enough" to ensure safe drilling in the Arctic Ocean?
It is true that hundreds of millions of dollars have been spent on marine science in US Arctic waters. But that doesn't mean the right questions have been asked, or that we have the results necessary to inform responsible management.
Unfortunately it turns out that we simply don't know enough about Arctic Ocean ecosystems to ensure our actions won't inadvertently stress species to the point of affecting animal populations and the indigenous peoples who depend on them.
...Read the full piece on the New Scientist website. | <urn:uuid:8a5094ac-8385-4274-8624-963dc433cfa1> | 3.53125 | 218 | Truncated | Science & Tech. | 50.771927 |
It might be a completely new species--a very tricky new species.
Learning skills that will be invaluable in later foxhood
In the future, the great Pixel Wolves Of The Sky will look down below on the mutated fish. The wolves will be hungry but also weirded out.
Cliff the beagle can sniff out a dangerous bacterium just by smelling patients--no stool sample or long lab analysis necessary.
Researchers discover an adorable (yet scary!) species of slow loris.
Find out how these arachnids avoid getting trapped in their goo.
Research on how the deadly fungus affects immune systems may help HIV research.
Following the shooting of a tagged Yellowstone grey wolf just outside the park's borders in Wyoming--the eighth such wolf shot this season--the state of Montana has banned wolf hunting in areas adjacent to the park. The NYTimes quotes a Montana Fish, Wildlife, and Park commissioner who cites the "time and money and effort" that goes into the tagging and research of these wolves, as well as a Yellowstone biologist who still seems to be smarting from the loss, saying this is a "moderate" decision that addresses "some of the issues as far as the science." [NYTimes]
Wyoming's anti-scientific laws have allowed the most famous wolf in Yellowstone to be shot. Shooting wolves isn't only senseless--it actively harms the environment.
The benefits of living with an engineer
Aerial surveillance, radio tagging and ranger patrols aim to fight poaching in Asia and Africa.
The "spidernaut" Nefertiti has died. It was 10 months old. A "Johnson Jumper" spider, it was sent on board the International Space Station in July as part of an experiment; researchers watched to see if the spider would adapt its feeding behavior to weightlessness (it did). Nefertiti was returned to Earth after a 100-day stay, and the Smithsonian Institution's National Museum of Natural History then placed the spider in its insect zoo. The display opened to the public on November 29, but the spider died of natural causes yesterday morning. Rest in peace, spidernaut. [SPACE.com]
The elephant, Duchess, goes under the knife, with doctors using custom tools for the rare surgery.
By tracking the cows' diets, and thus their methane production, researchers can help slow global warming.
Scientists in the UK injected dogs with cells grown from the lining of their noses, which continually regenerates. | <urn:uuid:c9089bd5-0d7f-494b-8f49-de75bd415051> | 2.6875 | 506 | Content Listing | Science & Tech. | 51.831468 |
Anyone who has ever seen a streaky line of vapor, known as a contrail, behind a high-flying aircraft knows that airplanes can produce their own clouds. But in rarer cases, aircraft can also punch round holes, such as the one over Antarctica pictured here, or carve long channels through existing, natural clouds. Those formations arise from the strong cooling effects of airflow over a plane’s propeller blades or a jetliner’s wing. A study published recently in the journal Science reports that cooling can spontaneously freeze water droplets in the cloud and stimulate precipitation. The phenomenon requires a specific set of cloud conditions and is thus unlikely to have significant large-scale effects, but it could affect regional weather near airports. | <urn:uuid:f059d02f-96af-45bf-b069-b425bc15721c> | 3.859375 | 147 | Knowledge Article | Science & Tech. | 34.675756 |
Workbook for BaBar Offline Users - Writing Code
Using an Object Oriented design approach to make proper use of C++.
Object Oriented programming offers a powerful model for writing
computer software. Objects are "black boxes" which send and receive
messages. This approach speeds the development of new programs, and,
if properly used, improves the maintenance, reusability, and
modifiability of software by limiting the dependences among the
various objects which are coded.
OO Analysis and Design brings in a new approach to modelization
with respect to traditional (procedural) methods, understanding
the OO vs SA/SD analysis &
design characteristics is important. The C++ language offers an
easier transition via C, but it still requires an OO design approach
in order to make proper use of this technology. This can often be a
major problem for experienced C programmers.
Object Orientation relies heavily upon concepts and terminology that
make up the boundaries of the paradigm. Principles and definitions cannot be
ignored in order to program within the OO paradigm boundaries.
A rudimentary discussion of Object Orientation may be found in the
Object Orientation section of this
You may want to look at the FAQ to get quick answers to the basic
ideas behind OO.
As an introduction to Object Oriented Programming, Bob Jacobsen and
Dave Quarrie presented a series of lectures at SLAC in 1995. Like the
C++ course, these lectures were recorded and the videos are available
or loan and for copy from SLAC and in Europe.
The transparencies from the talks are available on the web.
Some useful books on OO design are:
- Robert C. Martin, "Designing Object-Oriented C++ Application Using
the Booch Method", Prentice-Hall Inc, 1995, ISBN 0-13-203837-4.
- E.Gamma, R.Helm, R.Johnson and J.Vlissides, ``Design Patterns'',
Addison-Wesley, ISBN 0-201-63361-2.
- I.White, ``Using the Booch Method: a Rational Approach'',
Benjamin Cummins, ISBN 0-8053-0614-5.
- G.Booch, ``Object Oriented Analysis and Design with
Applications (2nd ed)'', Benjamin Cummins, ISBN 0-8053-5340-2.
Methods (functions) in OO are the way to develop software following a
controlled and repeatable process. Methods rely on the parallel
production of documentation (mostly
OO diagrams) and code). Examples are:
The C++ Language
You may or may not do OO programming with C++ (not even so-called pure-OO
languages force you to go OO). If ever, these books are gold-plated:
if you don't have them, buy them (and read them). They cover what you should
and should not do with OO/C++.
C++, Second Edition, 224 pgs, Addison-Wesley, 1998, ISBN 0-201-92488-9.
Covers 50 topics in a short essay format.
Effective C++, 336 pgs, Addison-Wesley, 1996, ISBN 0-201-63371-X. Covers
35 topics in a short essay format.
Gamma et al., Design
Patterns, Elements of Reusable Object-Oriented Software, Addison-Wesley,
ISBN 0-201-63361-2. Patterns and what OO is all about: The introduction
should be carved into each developer's brain.
While Meyers works constitute the do's and dont's, the following two
works cover most if not all aspect of legal C++.
A series of 8 lectures introducing users to C++ programming were given
by Paul Kunz during 1995. These lectures were all video'd and
the videos are available for loan and copy from SLAC and in Europe.
The full transparencies for the course are available on the WWW
(copies of these will be essential when viewing the videos !) at /BFROOT/www/Computing/Programming/ProgC++class.html.
The Paul Kunz course closely follows the following text:
Lippman and Lajoie, C++ Primer, Third Edition, 1237 pgs, Addison-Wesley,
1998, ISBN 0-201-82470-1. Very readable/approachable.
Stroustrup, The C++ Programming Language, Third Edition, 646 pgs, Addison-Wesley,
1998, ISBN 0-201-53992-6. Covers a lot of groun
This books contains many code
examples, all of which are available from the Web, via links on the
above pages. The book is really aimed at teaching the basics of C++
to Scientists and Engineers (i.e. FORTRAN programmers).
J. Barton and Lee R. Nackman, ``Scientific and Engineering C++: An
Introduction with Advanced Techniques and Examples'',published by
Addison-Wesley (ISBN 0-201-53393)
Other useful texts for learning C++ are:
- Stanley B. Lippman,``C++ Primer'', published by Addison Wesley.
( ISBN 0-201-54848-8 )
- Ira Pohl, ``Object Oriented Programming Using C++ - 2nd Edition'',
published by Addison Wesley ( ISBN 0-201-89550-1 )
- Scott Meyers,``Effective C++'', published by Addison Wesley.
( ISBN 0-201-56364-X )
- Scott Meyers,``More Effective C++'', published by Addison Wesley.
( ISBN 0-201-63371-X )
In general, each file in a package should represent a class, and each
class should contain methods (functions) to do just one task. The
classes are defined in the header files (*.hh) which represent the
class interface. In it you state what the class is called and declare
the variables and functions within that class. The .cc file is just
the implementation of the functions. The convention:
<class declaration info>
should be adhered to for header files to avaoid the header file being
"#include"'d more than once at compilation stage.
Classes involving the Objectivity database are different - they
contain a .cc file and a .ddl file (from which the compiler
automatically creates a *_ddl.hh in a tmp directory when it's
processing). These files are beyond the scope of this workbook
chapter, and will be dealt with in the WorkBook chapter Writing Persistent Classes
Writing messages in a way that allows program recover, allows logging
and allows the user to control verbosity
General Related Documents:
Last modification: 5 August 2004
Last significant update: 9 October 2002 | <urn:uuid:7219644c-1d7e-486c-9561-60d1fb985e48> | 3.296875 | 1,508 | Tutorial | Software Dev. | 59.950687 |
|Oracle® OLAP DML Reference
10g Release 1 (10.1)
Part Number B10339-02
The RTRIM function removes characters from the right of a text expression, with all the rightmost characters that appear in another text expression removed. The function begins scanning the base text expression from its last character and removes all characters that appear in the trim expression until reaching a character that is not in the trim expression and then returns the result.
TEXT or NTEXT based on the data type of the first argument.
RTRIM (text-exp [, trim-exp])
A text expression that you want trimmed.
A text expression that is the characters to trim. The default value of trim-exp is a single blank.
The following example trims all of the right-most a's from a string.
SHOW RTRIM('Last Wordxxyxy','xy') Last Word | <urn:uuid:cd520809-c4ad-45d4-9fa2-72200ab700b1> | 3.40625 | 191 | Documentation | Software Dev. | 66.864123 |
I'm Dave Thurlow for the Mount Washington Observatory and this is The Weather Notebook. Around the beginning of this century, there were few scientists who had much of an idea about how rain, hail, sleet, and snow form. It was, and still is, easy to get the general process of water vapor turning to liquid water or ice, but what happens at the instant when cloud droplets floating in the air, become a raindrop or a snowflake.
In 1885, a farmer from Jericho, Vermont asked the same question. Forty years later, this man with no high school education, received the first cash research prize ever awarded by the American Meteorological Society and was known around the world as Wilson Bentley, the Snowflake Man. Bentley spent his life taking thousands of detailed and beautiful photographs of snowflakes, recording in detail the nature of the storm that produced them. By 1905, he had theories about the role of ice crystals in the formation of snow and rain, and established basic temperature profiles of the sky above by simply examining what falls from it.
To this day, after years of high tech study, his findings have proven largely to be true. But in the early 1900's nobody in the scientific community paid Mr. Bentley any attention at all. Because he wrote about his work eloquently and emotionally, scientists thought he was a nut. But while many of his critic's names are buried away in the footnotes of weather research history, Snowflake Bentley's name lives on.
The Weather Notebook is produced by the Mount Washington Observatory...funded by The National Science Foundation and underwritten by Subaru, maker of the all Weather Legacy. Subaru -- the beauty of All-Wheel Drive. | <urn:uuid:c68ca766-d280-4f15-9e5e-e03d41a035f6> | 3.3125 | 347 | Audio Transcript | Science & Tech. | 50.238824 |
This chart is a comprehensive view of global, anthropogenic greenhouse gas (GHG) emissions. The chart is an updated version of the original chart, which appeared in Navigating the Numbers: Greenhouse Gas Data and International Climate Policy.
One of the greatest challenges relating to global warming is that greenhouse gases result—directly or indirectly—from almost every major human industry and activity. This chart shows these industries and activities, and the type and volume of greenhouse gases that result from them. It includes emissions estimates from a range of international data providers, in an attempt to account for all significant GHG emissions sources.
In 2005, total GHGs are estimated at 44,153 MtCO2 equivalent (million metric tons). CO2 equivalents are based on 100-year global warming potential (GWP) estimates produced by the IPCC. 2005 is the most recent year for which comprehensive emissions data are available for every major gas and sector.
Comparison to 2000
If you are familiar with the original version of this chart, you may be interested to know what has changed in the update, and why. Total global emissions grew 12.7% between 2000 and 2005, an average of 2.4% a year. However, individual sectors grew at rates between 40% and near zero, and there are substantial differences in sectoral growth rates between developed and developing countries.
The other major difference in this version of the chart concerns the Land Use Change sector, which comprised 18.2% of GHG emissions in the previous version of the chart, and only 12.2% of emissions in this version. The apparent decrease is entirely due to revised methodologies used to calculate deforestation in the underlying FRA data, and not to any actual decrease in deforestation rates. Read the working paper for this chart for more information. | <urn:uuid:950ac813-d5e0-46c8-a195-4f8acf42bc02> | 3.53125 | 364 | Knowledge Article | Science & Tech. | 40.826894 |
This pie chart shows the relative likelihood of observing particular other species commonly observed near Allophylus edulis
These species are those which most commonly occur in our observation database near Allophylus edulis. Observations favor some phyla over others. Typically Bacteria, Fungi, Protozoa, and Arthropods are more common in the field than in our records.
In sections below, we make some habitat inferences based on the known habitat preferences of those species most commonly associated with Allophylus edulis.
cultivated areas, deciduous woods and forests, desert, disturbed sites, fields, forests, grasslands, hammocks, meadows, open forests, pasture, pine forests, rain forest, steppes, thickets.
dry slopes, flood plains, roadsides, rock outcrops, sand dunes, streamsides.
clay, limestone, loam, sandy areas, sandy soil, thin soil.
bogs, brackish water, ditches, dry areas, flood plains, lagoon, lakes, marshes, ponds, rivers, shores, stream banks, streams, swamps. | <urn:uuid:b7d5eee8-3ff2-43e3-b9ea-e55a5250661d> | 3.140625 | 240 | Structured Data | Science & Tech. | 21.488161 |
States are the basic units of the state machines. In UML 2.0 states can have substates.
Execution of the diagram begins with the Initial node and finishes with Final or Terminate node or nodes. Please refer to UML 2.0 Specification for more information about these elements.
State Machine diagrams describe the logic behavior of the system, a part of the system, or the usage protocol of it.
On these diagrams you show the possible states of the objects and the transitions that cause a change in state.
State Machine diagrams in UML 2.0 are different in many aspects compared to Statechart diagrams in UML 1.5.
Copyright(C) 2008 CodeGear(TM). All Rights Reserved.
What do you think about this topic? Send feedback! | <urn:uuid:ea692ff2-4976-4580-b298-dbf1d0cd0664> | 3.046875 | 162 | Documentation | Software Dev. | 60.666143 |
New in version 2.1.
The inspect module provides several useful functions to help get information about live objects such as modules, classes, methods, functions, tracebacks, frame objects, and code objects. For example, it can help you examine the contents of a class, retrieve the source code of a method, extract and format the argument list for a function, or get all the information you need to display a detailed traceback.
There are four main kinds of services provided by this module: type checking, getting source code, inspecting classes and functions, and examining the interpreter stack.
The getmembers() function retrieves the members of an object such as a class or module. The sixteen functions whose names begin with “is” are mainly provided as convenient choices for the second argument to getmembers(). They also help you determine when you can expect to find the following special attributes:
|__file__||filename (missing for built-in modules)|
|__module__||name of module in which this class was defined|
|__name__||name with which this method was defined|
|im_class||class object that asked for this method||(1)|
|im_func or __func__||function object containing implementation of method|
|im_self or __self__||instance to which this method is bound, or None|
|__name__||name with which this function was defined|
|func_code||code object containing compiled function bytecode|
|func_defaults||tuple of any default values for arguments|
|func_doc||(same as __doc__)|
|func_globals||global namespace in which this function was defined|
|func_name||(same as __name__)|
|generator||__iter__||defined to support iteration over container|
|close||raises new GeneratorExit exception inside the generator to terminate the iteration|
|gi_frame||frame object or possibly None once the generator has been exhausted|
|gi_running||set to 1 when generator is executing, 0 otherwise|
|next||return the next item from the container|
|send||resumes the generator and “sends” a value that becomes the result of the current yield-expression|
|throw||used to raise an exception inside the generator|
|traceback||tb_frame||frame object at this level|
|tb_lasti||index of last attempted instruction in bytecode|
|tb_lineno||current line number in Python source code|
|tb_next||next inner traceback object (called by this level)|
|frame||f_back||next outer frame object (this frame’s caller)|
|f_builtins||built-in namespace seen by this frame|
|f_code||code object being executed in this frame|
|f_exc_traceback||traceback if raised in this frame, or None|
|f_exc_type||exception type if raised in this frame, or None|
|f_exc_value||exception value if raised in this frame, or None|
|f_globals||global namespace seen by this frame|
|f_lasti||index of last attempted instruction in bytecode|
|f_lineno||current line number in Python source code|
|f_locals||local namespace seen by this frame|
|f_restricted||0 or 1 if frame is in restricted execution mode|
|f_trace||tracing function for this frame, or None|
|code||co_argcount||number of arguments (not including * or ** args)|
|co_code||string of raw compiled bytecode|
|co_consts||tuple of constants used in the bytecode|
|co_filename||name of file in which this code object was created|
|co_firstlineno||number of first line in Python source code|
|co_flags||bitmap: 1=optimized | 2=newlocals | 4=*arg | 8=**arg|
|co_lnotab||encoded mapping of line numbers to bytecode indices|
|co_name||name with which this code object was defined|
|co_names||tuple of names of local variables|
|co_nlocals||number of local variables|
|co_stacksize||virtual machine stack space required|
|co_varnames||tuple of names of arguments and local variables|
|__name__||original name of this function or method|
|__self__||instance to which a method is bound, or None|
Changed in version 2.2: im_class used to refer to the class that defined the method.
Return all the members of an object in a list of (name, value) pairs sorted by name. If the optional predicate argument is supplied, only members for which the predicate returns a true value are included.
Return a tuple of values that describe how Python will interpret the file identified by path if it is a module, or None if it would not be identified as a module. The return tuple is (name, suffix, mode, mtype), where name is the name of the module without the name of any enclosing package, suffix is the trailing part of the file name (which may not be a dot-delimited extension), mode is the open() mode that would be used ('r' or 'rb'), and mtype is an integer giving the type of the module. mtype will have a value which can be compared to the constants defined in the imp module; see the documentation for that module for more information on module types.
Changed in version 2.6: Returns a named tuple ModuleInfo(name, suffix, mode, module_type).
Return true if the object is a Python generator function.
New in version 2.6.
Return true if the object is a generator.
New in version 2.6.
Return true if the object is an abstract base class.
New in version 2.6.
This is new as of Python 2.2, and, for example, is true of int.__add__. An object passing this test has a __get__ attribute but not a __set__ attribute, but beyond that the set of attributes varies. __name__ is usually sensible, and __doc__ often is.
Methods implemented via descriptors that also pass one of the other tests return false from the ismethoddescriptor() test, simply because the other tests promise more – you can, e.g., count on having the im_func attribute (etc) when an object passes ismethod().
Return true if the object is a data descriptor.
Data descriptors have both a __get__ and a __set__ attribute. Examples are properties (defined in Python), getsets, and members. The latter two are defined in C and there are more specific tests available for those types, which is robust across Python implementations. Typically, data descriptors will also have __name__ and __doc__ attributes (properties, getsets, and members have both of these attributes), but this is not guaranteed.
New in version 2.3.
Return true if the object is a getset descriptor.
getsets are attributes defined in extension modules via PyGetSetDef structures. For Python implementations without such types, this method will always return False.
New in version 2.5.
Return true if the object is a member descriptor.
Member descriptors are attributes defined in extension modules via PyMemberDef structures. For Python implementations without such types, this method will always return False.
New in version 2.5.
Clean up indentation from docstrings that are indented to line up with blocks of code. Any whitespace that can be uniformly removed from the second line onwards is removed. Also, all tabs are expanded to spaces.
New in version 2.6.
Get the names and default values of a function’s arguments. A tuple of four things is returned: (args, varargs, varkw, defaults). args is a list of the argument names (it may contain nested lists). varargs and varkw are the names of the * and ** arguments or None. defaults is a tuple of default argument values or None if there are no default arguments; if this tuple has n elements, they correspond to the last n elements listed in args.
Changed in version 2.6: Returns a named tuple ArgSpec(args, varargs, keywords, defaults).
Get information about arguments passed into a particular frame. A tuple of four things is returned: (args, varargs, varkw, locals). args is a list of the argument names (it may contain nested lists). varargs and varkw are the names of the * and ** arguments or None. locals is the locals dictionary of the given frame.
Changed in version 2.6: Returns a named tuple ArgInfo(args, varargs, keywords, locals).
When the following functions return “frame records,” each record is a tuple of six items: the frame object, the filename, the line number of the current line, the function name, a list of lines of context from the source code, and the index of the current line within that list.
Keeping references to frame objects, as found in the first element of the frame records these functions return, can cause your program to create reference cycles. Once a reference cycle has been created, the lifespan of all objects which can be accessed from the objects which form the cycle can become much longer even if Python’s optional cycle detector is enabled. If such cycles must be created, it is important to ensure they are explicitly broken to avoid the delayed destruction of objects and increased memory consumption which occurs.
Though the cycle detector will catch these, destruction of the frames (and local variables) can be made deterministic by removing the cycle in a finally clause. This is also important if the cycle detector was disabled when Python was compiled or using gc.disable(). For example:
def handle_stackframe_without_leak(): frame = inspect.currentframe() try: # do something with the frame finally: del frame
The optional context argument supported by most of these functions specifies the number of lines of context to return, which are centered around the current line.
Get information about a frame or traceback object. A 5-tuple is returned, the last five elements of the frame’s frame record.
Changed in version 2.6: Returns a named tuple Traceback(filename, lineno, function, code_context, index). | <urn:uuid:1243e50d-ecd7-4ea6-b13f-efb27d1010a4> | 2.734375 | 2,249 | Documentation | Software Dev. | 41.128717 |
A lightning storm started this cluster of wildfires in the Cascade Mountains of Oregon on August 24, 2011. Burning through forest, grass, and brush, the fires had covered 90,436 acres as of September 1. They are 25 percent contained.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired these images on September 1. The fires, collectively called the High Cascades Complex are outlined in red. The top image shows the region in natural color, similar to what the human eye sees. In this image, smoke hangs over the Cascade Mountains. Newly burned land is dark brown, similar in tone to the natural land cover in the desert east of the dark green mountains.
The lower image combines infrared and visible light in a false color image that reveals the extent of the recently burned area. Here, freshly burned land is red, while plant-covered land is green, and bare or sparsely vegetated land is tan. In this scene, the Razorback and Hancock Complex fires are more obvious. The Razorback Fire is the largest fire in the High Cascades Complex, having burned 51,943 acres as of September 1. The Hancock Complex burned 57,597 acres of grass and is entirely contained. All of the fires started in the same lightning storm on August 24.
- InciWeb. (2011, September 2). Hancock Complex. Accessed September 2, 2011.
- InciWeb. (2011, September 1). High Cascades Complex. Accessed September 2, 2011.
- Aqua - MODIS | <urn:uuid:f1a7838b-bc2f-4c4b-8683-60e5ebe8cfb3> | 3.171875 | 319 | Knowledge Article | Science & Tech. | 56.705348 |
Two Types of Photovoltaic Solar Cells
Photovoltaics, which directly convert sunlight into electricity, include both traditional, polysilicon-based solar cell technologies and new thin-film technologies. Thin-film manufacturing involves depositing extremely thin layers of photosensitive materials on glass, metal, or plastics. While the most common material currently used is amorphous silicon, the newest technologies use non-silicon-based materials such as cadmium telluride.
A key force driving the advancement of thin-film technologies is a polysilicon shortage that began in April 2004. In 2006, for the first time, more than half of polysilicon production went into PVs instead of computer chips. While thin films are not as efficient at converting sunlight to electricity, they currently cost less and their physical flexibility makes them more versatile than traditional solar cells.
China Poised to Become Leading Producer of Solar Cells in 2008
The top five PV-producing countries are Japan, China, Germany, Taiwan, and the United States. Recent growth in China is most astonishing: after almost tripling its PV production in 2006, it is believed to have more than doubled output in 2007. Having eclipsed Germany in 2007 to take the number two spot, China is now on track to become the number one PV producer in 2008. (See additional data from the Earth Policy Institute.)
Strong domestic production is not always a good indicator of domestic installations, however. For example, despite China's impressive production, PV prices are still too high for the average Chinese consumer. But large PV projects are expected to increase domestic installations.
Residential Use of Solar Cells Increasing Worldwide
Japan, the United States, and Spain round out the top four markets with 350, 141, and 70 megawatts installed in 2006, respectively. Thanks to a residential PV incentive program, Japan now has over 250,000 homes with PV systems. But the country is currently experiencing a decrease in the growth rate of PV installations resulting from the phase-out of the incentive program in 2005 and a limited domestic PV supply due to the polysilicon shortage.
In contrast, the growth in installations in the United States increased from 20 percent in 2005 to 31 percent in 2006, primarily driven by California and New Jersey. Initial estimates for the United States as a whole indicate that PV incentives, including a tax credit of up to $2,000 available under the U.S. Energy Policy Act of 2005 to offset PV system costs, helped to achieve an incredible 83 percent growth in installations in 2007.
Public Policies Drive Nonresidential Use of Solar Cells
Spain tripled its PV installations in 2006 to 70 megawatts. A building code that went into force in March 2007 requires all new nonresidential buildings to generate a portion of their electricity with PV. In September 2007, a 20-megawatt PV power plant, currently the largest in the world, came online in the Spanish town of Beneixama and is producing enough electricity to supply 12,000 homes.
Falling Prices are Making Solar Power Competitive with Coal
The average price for a PV module, excluding installation and other system costs, has dropped from almost $100 per watt in 1975 to less than $4 per watt at the end of 2006. With expanding polysilicon supplies, average PV prices are projected to drop to $2 per watt in 2010. For thin-film PV alone, production costs are expected to reach $1 per watt in 2010, at which point solar PV will become competitive with coal-fired electricity. | <urn:uuid:d1dbd0cf-3b53-4aaf-ac59-a0fd0e5e3b4f> | 3.46875 | 715 | Knowledge Article | Science & Tech. | 38.196721 |
The right hand side of the above line dynamically allocates a single integer on the heap returns a pointer of type int*. The left hand side of the above line implicitly copy constructs a pointer on the stack using the pointer returned from the new expression. It is the equivalent of writing:
int *myPtr(new int);
The result is that myPtr now points to a dynamically allocated piece of memory. Incidently, this needs to be released using delete when you have finished with it else you will have a memory leak.
The above line deletes the allocation that myPtr points to, any attempt to access the address myPtr currently still points to will yeild undefined behaviour.
Now you might see the problem with the code you posted...
Originally Posted by g.eckert
I previously tried something similar to this and the app kept crashing
cin>> *( myPtr ); //Store input into the value myPtr points to
The problem is that you have constructed an integer pointer myPtr but the pointer has not been initialised or assigned to point to a valid piece of memory. In effect, the pointer could be pointing anywhere. What you need to do is point it to a piece of memory that holds a valid integer. You can do this dynamically, or you can allocate a stack integer variable as follows.
int var = 0;
int *myPtr = &var; //now myPtr points somewhere valid.
//You can use myPtr from now on to access var
This aside, why on earth do you want to purposely use pointers to access everything? If you cannot access a single object directly, then the next best thing is accessing it by reference, but if that is not possible (through design constraints), then only as a last resort should you access by pointer. They should NOT be used when there is no need.
Last edited by PredicateNormative; April 17th, 2009 at 06:13 AM.
Hey thanks for clearing that up. Explained very well.
This program is for a CPS class and should demonstrate our knowledge of pointers. The directions say, 'write a function to sort an array using a bubble sort algorithm and a program to test it. Use pointer notation for the program'. I assumed this meant use pointers for everything. Now thinking about it more it might mean use pointer notation for the sorting function. I dont know, ill have to check about that but I agree with you it doesnt make sense to use pointers for size variables and such I thought I needed to because of the directions.
I think your original interpretation is correct, it looks like you are meant to use pointer notation for as much as possible. Although this isn't sensible for real world programming, I can understand it as an exercise as long as your lecturer goes on to point out that pointers should only be used when you have to use them (traversing an an array is an example).
Nope, I think "in-memory" sorting is a good example for the use of pointers. You don't move the objects in an array (of whatever sort), you just move pointers to the objects. I. e. you have an array of pointers to objects, sort it, and the pointers just point to different object than before. | <urn:uuid:91c813a8-5ade-4a3c-93a7-7f630c62b67a> | 2.921875 | 665 | Comment Section | Software Dev. | 58.503189 |
One of the most basic questions in mathematics is finding solutions to equations. In this post I want to make a short overview of the ways to solve some of the common forms of equations, and I also want to discus the history of how this solutions were found. This is only the first post about this subject, so it is mostly introductory.
For the simplest equations, the solutions are known for a long time, so I will only mention since what period the solutions were known, and will not discuss the ways they were developed. The most simple equation is an equation of the form:
The linear equations we now how to solve. So, what other types of equations we have? The next in line is the equation of the form:
If we will take b=-1 we will have an even harder problem. The equation becomes then x^2=-1. Until Gauss at the 18 century, such equations were considered unsolvable.
There are other, slightly more difficult to solve, second degree polynomials. The most general form is:
We can now move b to the second site, and get the equation:
It looks very similar to the equation we all learned in school, but an a is missing. However, our b is in fact the original b divided by a and so is c. If we will write b/a and c/a and move them a bit we will get:
Any second degree polynomial can be solved using this formula. In ancient Babylon, the problems were solved using this formula, but the solution process went without any symbols. It was done completely verbally. The Greeks also knew how to solve such problems, but they used geometry to solve the problem. I will write about how they did it, and the reasons for using geometry for such tasks in another post.
Now we know how to find the roots for second degree polynomial. But what about the third degree? Solutions for simple polynomials were known to the Babylonians. But they didn't know a formula for a general third degree polynomial. The same is true about the Greeks, and the Muslims. I once heard that when Archimedes was killed, his last words were a curse on those who will try to find the general solution for the third degree polynomial: "Cubics you shall not solve". I don't know if this is a true story. Probably it is just a legend. However it took a lot of time to find the solution for this problem. The solution was finally published by Cardano, a French mathematician, in the 16 century. He was the first one to publish it, but he himself got the solution from another mathematician - Tartaglia. In the 16 century the competition between mathematicians was very strong, so Tartaglia who was the first to find the solution, didn't want to publish it, but preferred to keep it to himself. When Cardano discovered that Tartaglia knows the solution, who put a lot of pressure on him to make him tell the solution. Finally Tartaglia agreed, but asked Cardano to make an oath that he will not publish the solution before he does. A few years passed and Cardano found out that the solution Tartaglia told him was found before by another mathematician and went unnoticed (the communication wasn't very good then). Upon discovering this, Cardano published the solution. The solution is anything but simple. Since it is significantly longer than for the second degree I will not write it in this post.
The next step is obviously a forth degree polynomial. This one was also solved in the 16 century, by a student of Cardano. Again, the solution is too long to be written in this post. If I will have time, I will write another post in which I will fully solve both of these questions. There two important facts about both of these solutions - they both are solutions by radicals, and they both effectively turn the problem into finding the roots of a polynomial of second (for the cubic) and third degree (for the forth degree polynomial).
And finally we get to the fifth degree - the quintic. The quintic is a polynomial of the form:
After seeing the solutions of the previous problems, everyone was sure that this problem would be solved as well. But no solution was found for a long period, until Abel came to the scene. He had an interesting idea - he started to question the generally accepted thought that there was a solution. He wrote a rather large (about 950 pages) proof that showed that it wasn't possible to find a general solution for any degree larger than 4. This proof wasn't accepted well. He sent it to Lagrange, but didn't got an answer. When he tried to get an official response from the Academy, the response was that "They don't find it usefully to look into his proof". Just before he died he received a letter from Cauchy, in which Cauchy wrote that he believes his proof is right. It was found out letter than while there is indeed no general formula for a degree larger than 4, there was a mistake in his proof. He skipped on one step, because he thought it was obvious - but it wasn't so. Anyway, it is now a generally accepted fact that there is no general formula.
There is also another interesting result that this discovery brought. You probably recognized the formula for the second degree polynomial, but I doubt you know the formula for the third degree or for the forth. They are no longer studied and are of no importance. It is possible to get a B.S. in math and don't know these formulas. It turned out that it is more practical to be able to solve specific examples, than to solve the general case. And for a specific problem we can use a computer who knows the formula.
However, we still need to be able to solve the quintic, as well as other polynomials. In the next post I will describe some tricks that are used for this purpose, and the general methods for finding solutions. | <urn:uuid:56fb8810-c673-46a7-95ce-8944ae2686d6> | 3.328125 | 1,248 | Personal Blog | Science & Tech. | 58.763916 |
Installs your own termination routine to be called by terminate.
The set_terminate function installs termFunction as the function called by terminate. set_terminate is used with C++ exception handling and may be called at any point in your program before the exception is thrown. terminate calls abort by default. You can change this default by writing your own termination function and calling set_terminate with the name of your function as its argument. terminate calls the last function given as an argument to set_terminate. After performing any desired cleanup tasks, termFunction should exit the program. If it does not exit (if it returns to its caller), abort is called.
In a multithreaded environment, terminate functions are maintained separately for each thread. Each new thread needs to install its own terminate function. Thus, each thread is in charge of its own termination handling.
The terminate_function type is defined in EH.H as a pointer to a user-defined termination function, termFunction that returns void. Your custom function termFunction can take no arguments and should not return to its caller. If it does, abort is called. An exception may not be thrown from within termFunction.
typedef void ( *terminate_function )( );
The set_terminate function only works outside the debugger.
There is a single set_terminate handler for all dynamically linked DLLs or EXEs; even if you call set_terminate your handler may be replaced by another, or you may be replacing a handler set by another DLL or EXE.
This function is not supported under /clr:pure.
For additional compatibility information, see Compatibility in the Introduction.
Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples. | <urn:uuid:484bc00f-85f1-4321-aed6-32ff47102ee4> | 3.21875 | 374 | Documentation | Software Dev. | 39.437421 |
Design your own scoring system and play Trumps with these Olympic Sport cards.
There is a long tradition of creating mazes throughout history and across the world. This article gives details of mazes you can visit and those that you can tackle on paper.
This activity challenges you to decide on the 'best' number to use
in each statement. You may need to do some estimating, some
calculating and some research.
Can you put these times on the clocks in order? You might like to
arrange them in a circle.
One day five small animals in my garden were going to have a sports day. They decided to have a swimming race, a running race, a high jump and a long jump.
Can you imagine where I could have walked for my path to look like
Look at different ways of dividing things. What do they mean? How might you show them in a picture, with things, with numbers and symbols?
Can you spot circles, spirals and other types of curves in these photos?
Problem solving is at the heart of the NRICH site. All the problems
give learners opportunities to learn, develop or use mathematical
concepts and skills. Read here for more information.
This task looks at the different turns involved in different Olympic sports as a way of exploring the mathematics of turns and angles.
What is the same and what is different about these tiling patterns and how do they contribute to the floor as a whole?
This is a collection of mathematical activities linked to the
Football World Cup 2006. These activities can easily be updated for
another football event or could be the inspiration for. . . .
Noticing the regular movement of the Sun and the stars has led to a desire to measure time. This article for teachers and learners looks at the history of man's need to measure things.
How can people be divided into groups fairly for events in the Paralympics, for school sports days, or for subject sets?
In this article, Alan Parr shares his experiences of the motivating effect sport can have on the learning of mathematics.
Jenny Murray describes the mathematical processes behind making patchwork in this article for students.
How does the time of dawn and dusk vary? What about the Moon, how does that change from night to night? Is the Sun always the same? Gather data to help you explore these questions. | <urn:uuid:6609c9c8-0830-44df-827f-97cb81e123c4> | 3.34375 | 490 | Content Listing | Science & Tech. | 60.717795 |
The Solar Polar Orbiter (SPO) Technology Reference Study (TRS) examines the feasibility of a mission to obtain true solar polar orbit at an altitude of less than 0.5 AU to perform remote sensing of the Sun and in situ measurements of the surrounding environment.
The Solar Polar Orbiter
The Solar Polar Orbiter has the following scientific objectives:
The Solar Polar Orbiter consists of a single spacecraft, launched on a Soyuz Fregat 2B from Kourou, French Guiana. The spacecraft will utilize a solar sail to lower its orbit to less than 0.5 AU before raising its inclination. After about 4 years the SPO spacecraft will achieve an inclination of approximately 83 degrees in the ecliptic coordinate frame. At this point the sail will be detached in order to perform undisturbed scientific measurements.
The preliminary concept for SPO employs a square solar sail with a total area of approximately 25 000 m². The characteristics of the sail are given in the table below.
The preliminary mass budget is given in the table below, outlining the spacecraft and payload masses.
Solar Sail Material: A lightweight material needs to be developed with the required optical properties to reduce system mass and requirements. The optical properties of the sail must also be preserved during the sail phase.
Solar Sail Deployment: The development of a lightweight deployment structure for a very large (~30 000 m²) sail is required.
Lightweight booms: Developments of lightweight booms with a length approaching 100 m are required. Such booms should have a specific mass of less than 100 g/m.
Solar Sail Attitude Control: There are several options for performing attitude control. The options currently under consideration include a gimbaled boom between the sail and spacecraft, moving masses along the boom structure, and tip vanes or thrusters on the booms.
Solar Sail Jettison Mechanism: The sail must be jettisoned upon reaching the final orbit in order to prevent interference with the instruments. This separation must take place with a minimum risk of collision.
This study was completed in 2004. It was carried out by SRE-PAM with the assistance of the University of Glasgow.
For further information about this study please contact the study manager:
Dr. Peter Falkner | <urn:uuid:310c42cb-21fa-4e88-a253-713ce71f63a9> | 3.28125 | 467 | Knowledge Article | Science & Tech. | 41.244828 |
Amongst all the excitement over the first results from Herschel, it’s easy to forget about its comparatively tiny American cousin Spitzer. Launched in 2003 with its 3 instruments IRAC, IRS and MIPS, Spitzer covers the infrared wavelengths from around 3 to 150 microns – a region that from Earth is either totally inaccessible or severely hampered by atmospheric absorption. With its 85-cm diameter primary mirror, it’s easy to dismiss Spitzer as belonging to a former era. But new science is coming out of Spitzer data every day, and vast quantities of data remain unpublished in the archives. The big legacy surveys in particular, such as c2d (Cores to Disks) and the galactic plane surveys GLIMPSE and MIPSGAL, have released a wealth of data into the public domain, throwing light on old problems and unveiling new mysteries to solve.
One interesting phenomenon witnessed on the images from the GLIMPSE survey was a curious population on extended green objects (EGOs). Catalogued by Cyganowski et al in 2008, these “green fuzzies” appear to be associated with regions of massive star formation – many of them lie in or very near to infrared dark clouds, known to harbour the earliest forms of massive star birth, or are associated with methanol masers, strong radio emission caused by excitation of methanol molecules by infrared radiation from dust. Their green colour is in a sense incidental, arising from the way we construct 3-colour images from the Spitzer camera IRAC. IRAC takes images in 4 channels, at 3.6, 4.5, 5.8 and 8 microns, and typically an red-green-blue image uses the 8, 4.5 and 3.6 micron data, respectively. In this picture, “green” indicates that the object has an unusually high flux in the 4.5 micron band.
This characteristic in a spatially extended object instantly raises a flag among star formation aficionados, as this band, stretching from 4 to 5 microns, contains some prominent spectral lines from molecular hydrogen (H2) and carbon monoxide (CO), commonly seen in emission in outflow regions. Young protostars that are growing by accreting material from their surrounding cloud often have strong streams fo outflowing material. Where the outflow collides with the surrounding interstellar medium, the resulting shocks give rise to this strong emission. So this fuzzy greenness could indicate the presence of a young massive star growing deep inside a dense molecular cloud, even though we can’t yet see the actual young star itself.
Even though relatively few massive stars are produced compared with “regular” low mass stars, and their lifetimes are much shorter, their immense output of energy, particularly in heavy elements that they alone can produce and eventually blast into the interstellar medium as supernovae, has galactic-scale influence. But their rapid evolution and long embedded formation stage makes them very elusive objects to study, and astronomers have to rely on indirect signposts of massive stellar birthplaces to get an insight into the process. The prospect of these green fuzzies as an additional telltale sign of young massive protostars is therefore well worth exploring. But IRAC’s broad band imaging alone can’t reveal the true nature of EGOs – for that we need spectroscopy.
This week, De Buizer & Vacca of NASA Ames Research Center posted a paper to astro-ph claiming the first spectroscopic identification of green fuzzies over the IRAC wavelength range of 4-5 microns, allowing them to examine directly the source of the emission in these objects, precisely at the wavelengths that they appear strong in. They used the mid-IR instrument NIRI on the 8-m ground-based Gemini North telescope to observe two of the objects from Cyganowski’s catalogue. And interestingly, the objects appeared to be quite different in nature, suggesting that they’re not a clear-cut signpost of anything.
The first fuzzy, shown on the left above, looks like some sort of object-with-outflow, and the spectrum does suggest that that is the case. The central source’s spectrum is consistent with a deeply embedded massive forming star, with all of its radiation below 3.5 microns or so being absorbed by a thick shell of dust. The green knotty areas surrounding it show only strong emission in molecular hydrogen lines with no underlying continuum emission, probably emanating from shocked gas in an outflow from the central young star.
The second fuzzy, however, has a very different shape – it looks a bit comet-shaped and there’s no clear axis along which you might expect to see an outflow. The spectrum is also very different: it doesn’t show any particular emission features in the IRAC 4.5 micron filter region, although its spectrum does suggest the presence of a deeply embedded young massive star at the brightest location. But there’s no evidence of an outflow. The authors suggest that in this case, the object is not particularly bright at 4.5 microns, it’s unusually faint in the red and blue channels (8 and 3.5 microns, respectively) – and this produces the same appearance. At 3.5 micron, the radiation is likely just being absorbed by dust, while the 8 micron flux is low from a nearby silicate absorption that is strong in embedded young stars.
This is not an groundbreakingly new result. Two objects don’t exactly make “a sample”, so we don’t learn anything conclusive about the nature of the Spitzer green fuzzies. And in a way, it’s not unexpected that there are several mechanisms responsible for the enhanced 4.5 micron flux: the galactic plane is a chaotic cauldron of gas and dust, and these objects we’re seeing in the Spitzer images are all at different distances and depths with different amounts and compositions of intervening material. But the spectra are nice, and it’s a good example of how we’re slowly chipping away at new questions coming out of groundbreaking facilities, even many years after their launch. Hundreds of these green fuzzies have been identified from Spitzer images, and other authors have defined differing methods of identifying them, and all are excellent follow-up fodder for current large ground-based telescopes and new observatories and instruments coming online soon. For a phenomenon as important as the birth formation of massive stars, it’s worth exploring anything that can give us a glimpse into the heart of the formation process.
James M. De Buizer, & William D. Vacca (2010). Direct Spectroscopic Identification of the Origin of ‘Green Fuzzy’ Emission in Star Forming Regions accepted in ApJ arXiv: 1005.2209v1
C. J. Cyganowski, B. A. Whitney, E. Holden, E. Braden, C. L. Brogan, E. Churchwell, R. Indebetouw, D. F. Watson, B. L. Babler, R. Benjamin, M. Gomez, M. R. Meade, M. S. Povich, T. P. Robitaille, & C. Watson (2008). A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new
sample of massive young stellar object outflow candidates Astronomical Journal, 136 (6), 2391-2412 arXiv: 0810.0530v1 | <urn:uuid:23f28de9-ac0f-4d53-b670-96ba643bc7ab> | 3.25 | 1,575 | Personal Blog | Science & Tech. | 51.490963 |
Phylogeny of the Invertebrates
The tree below was redrawn from the information and cladograms of the Phylogeny Wing of the University of California Museum of Paleontology. The animal phyla represented have been selected for familiarity and to provide context for phyla often exhibited in aquaria and that might be seen at the James R. Record Aquarium of the Fort Worth Zoo. My selection of which "minor phyla" to include both on the tree and in the list below is frankly idiosyncratic. Common names have been used to identify each of the phyla when one was available. Below you will find a listing of the scientific names of each phylum, and examples of its more common members. Links to representative animals for phyla that can be seen at the zoo have been provided, both from the phylum list and from the tree.
Contrary to my usual practice at WhoZoo, I have also included links from the list to discussions of less familiar phyla at other web sites; these are marked with an asterisk(*). Sources for information on these animals are included in the source list below the tree. Only animals that can be seen at the James R. Record Aquarium have been linked from the tree itself. Note: with the closing of the Aquarium, these animals can no longer be seen at the Fort Worth Zoo.
- Phylum Porifera: the *sponges
- Phylum Cnidaria: anemones, jellyfish and corals
- Phylum Platyhelminthes: the flatworms
- Phylum Echinodermata: sea stars, sea urchins, sand dollars, sea lilies
- Phylum Chordata, subphylum Urochordata: the *sea squirts
- Phylum Chordata, subphylum Cephalochordata: the *lancelets
- Phylum Chordata, subphylum Vertebrata: the vertebrates
- Phylum Mollusca: bivalves, snails, *octopuses and squid
- Phylum Pogonophora: this relatively unfamiliar phylum has been included because the Vestimentiferan worms -- the giant red tube-building worms that colonize the waters around *deep sea volcanic vents -- are closely related to them.
- Phylum Annelida: earthworms and fanworms
- Phylum Rotifera: the *rotifers
- Phylum Nematoda: the *nematodes
- Phylum Onychophora: the *velvet worms
- Phylum Tardigrada: the *water bears -- charming, stumpy-legged segmented animals
- Phylum Arthropoda: because the ranks of the major taxa within this large and successful group are variously defined, I have included the groups without a rank assignment below:
- Myriapods: centipedes and millipedes
- Insects: beetles, flies, butterflies, roaches, ants and bees, bugs, grasshoppers, phasmids (AKA stick insects)and other insects.
- Crustaceans: crabs, shrimp and lobsters, and the giant isopods that can be seen in the James R. Record Aquarium.
- Merostomata: the horseshoe crabs
- Arachnida: spiders, scorpions, ticks and mites.
- Trilobita: the *trilobites -- extinct arthropods commonly found as fossils.
Additional notes: Deuterostomes are animals whose embryos develop a mouth as a secondary embryonic structure opposite to the blastopore, which opens into the primitive gut. Protostomes are animals that develop their mouths from or very near to the blastopore. Ecdysozoans are animals that molt their cuticles or exoskeletons as they grow. Lophotrochozoans are a group of animals that have either a trochophore (toplike) larva or a feeding organ (lophophore) composed of a ring of ciliated tentacles.
Sources and links to offsite information about invertebrates:
- Allen G. Collins, Brian R. Speer and Ben Waggoner. The Metazoa: University of California Museum of Paleontology.
- Allen G. Collins and Ben Waggoner.Introduction to the Porifera. University of California Museum of Paleontology
- Ben Waggoner and B. R. Spear. Introduction to the Flatworms. University of California Museum of Paleontology.
- James Wood. The Cephalopod Page
- Wim van Egmond and Jan Parmentier. Sea Squirts, Our Distant Cousins
- Ben Waggoner. Introduction to the Lancelets. University of California Museum of Paleontology.
- Hot Vents. Marine Biology at State University of New York.
- Roy Winsby. Rotifers and How to Find Them.
- Ben Waggoner and Brian R. Speer. Introduction to the Nematoda. University of California Museum of Paleontology.
- Ben Waggoner and Allen G Collins. Introduction to the Onychophora. University of California Museum of Peleontology.
- Phil Greaves. Tardigrades.
- Sam Gon III. A Guide to the Orders of Trilobites
- University of California Museum of Paleontology. Introduction to the Lophotrochozoa
- University of California Museum of Paleontology. Introduction to the Ecdysozoa. | <urn:uuid:0f15a9b0-1a04-4b08-9255-f9f7b26d89ac> | 2.890625 | 1,166 | Structured Data | Science & Tech. | 28.209193 |
The redshift (Z) and Early Universe Spectrometer (ZEUS) is a direct detection, submillimeter echelle grating spectrometer designed to study star formation in the Universe from about 2 billion years after the Big Bang to the present through spectroscopy of distant star forming galaxies. The sensitivity of ZEUS enables spectroscopic studies in many of the most important gas cooling lines. From local (z<0.1) systems, these lines include the CO(J=8-7, 7-6, and 6-5) and 13CO(6-5) rotational lines, and the 370 and 610 um [CI] fine-structure lines which probe the neutral gas and far-UV radiation fields. From distant (z> 1) galaxies, we are using the redshifted fine-structure lines of [CII] 158 um, [OIII] 88 um, [OI] 63 um, and [NII] 122 and 205 um which probe stellar radiation fields and its effects on both the neutral and ionized gas components of the interstellar medium.
ZEUS is diffraction limited, attains sensitivity very close to the background limit on large submillimeter telescopes, and
has a resolving power ~ 1000. It therefore has unsurpassed sensitivity (corresponding to single-side-band receiver
temperatures < 40 K) for detecting broad lines from faint, point sources, enabling exciting new science portions of which we detail
ZEUS is designed for use in the 350, 450, and 610 um telluric windows on large submillimeter telescopes such as the 10.4 m Caltech Submillimeter Observatory (CSO), the 15 m James Clerk Maxwell Telescope (JCMT), and the 12 m Atacama Pathfinder EXperiment (APEX) telescope. The ZEUS grating is a 35 cm long echelle with a 5th order blaze wavelength of 355 um operated in near Littrow mode. By tilting the grating we access the spectral range between 333 and 381 microns, and 416 to 477 in 5th and 4th orders of the grating providing near complete coverage of the 350 and 450 micron telluric windows. It is straightforward to access the 610 um telluric window (555 to 636 um coverage in 3rd order of the echelle), but we have not done this to date.
Distant galaxies are essentially point sources compared with the 7-10" diffraction limited beams delivered by 10 m class submillimeter telescopes in the 350 and 450 micron windows. For instance, at the distance of the nearest ULIRG galaxy (Arp 220, d = 72 Mpc) a 7" beam corresponds to 2.4 kpc linear extent. To maximize sensitivity for point source detection given background limited operation, we operate ZEUS with a near diffraction limited slit width. On the CSO we have used 8.7" and 10.8" slits which corresponds to 1.1 and 1.37 lambda/D at the middle of our wavelength coverage (400 um). ZEUS achieves resolving powers between 565 and 1600 depending on the wavelength and entrance slit width over the 350 and 450 um bands. This resolving power is well matched to extragalactic lines widths (~ 300 km/sec), optimizing sensitivity for detection of weak lines. The resolving power is ~ 1200 at 372 microns, sufficient to well resolve the astrophysically important CO(7-6) and 370 [CI] lines that are spaced by only 1000 km/s.
The current ZEUS detector array is a 1 x 32 pixel neutron-transmutation doped silcon bolometer array kept at 220 mK with a dual stage 3He refrigerator. The array was manufactured by S.H. Moseley's group at Goddard Space Flight Center. The 1 mm square pixels are well matched to the slit width so that most of the line flux from a monochromatic point source will fall on a single pixel. The 1 x 32 pixel format yeilds an instantaneous spectrum of 32 spectral elements (instantaneous coverage up to 3% bandwidth) on a single beam on the sky. At present, we have our final bandpass filters located directly in front of the array, so that the 32 element spectrum is split -- one 16 pixel half operates in 4th order, while the other half operates in 5th order of the grating. This eliminates the complexity of a milli-Kelvin filter wheel in the system, and enables simultaneous observations in both telluric windows. A line co-incidence is 12CO(6-5) in the 450 um window can be observed simultaneously with 13CO(8-7) in the 350 um window.
A more detailed design description is found elsewhere on this page (see link) and in our publication list (see link).
ZEUS can accomodate a much larger format array -- about 54 pixels spectrally, and
20 spatially, so that a 54 spectral element spectrum can be delivered for 20 beams on the sky along a long slit simultaneously.
We are creating a multi-color, multi-beam version of ZEUS, ZEUS-2 (see link).
Since late 2006, we have enjoyed five very successful runs with ZEUS on the 10.4 m CSO. We detected the CO(6-5),
CO(7-6), and [CI] 370 um lines from about two dozen nearby starforming galaxies and ultraluminous galaxies. We also
detected the CO(8-7) line from five ULIRGs, 13CO(6-5) from two galaxies, and the redshifted [CII] line emission
from six galaxies at redshifts between 1.1 and 1.8. These lines trace the excitation of the neutral interstellar medium and are
important coolants, enabling cloud collapse to form stars.
First Detection of 13CO(6-5) from an External Galaxy
Our detection of the 13CO(6-5) line from the nucleus of NGC 253 is the first detection of the 13CO(6-5)
line from an external galaxy, and the first detection of any 13CO transition greater than J=3-2 from a source
beyond the Magellanic clouds. We detected the line from the nuclear
regions of the starburst galaxy, NGC 253, where at a distance of 2.5 pc, our 11" beam subtends 275 kpc. We observed the 13CO(6-5)
the 12CO(6-5), the 13CO(6-5), and [CI] 370 um lines from NGC 253, mapping the last three lines (right). The
13CO(6-5) line is bright, at ~ 7% of the line flux in the 12CO(6-5) line indicating optically thick emission
in the latter. We model the observed run of CO and 13CO line emission with J using a large velocity gradient (LVG) method, and find that 35 to 60% of the molecular
gas mass in the nuclear regions is both warm (T ~ 110 K), and dense (~ 10 4cm -3) in support of our prior
work based on the detection of the 12CO(7-6) line (Bradford et al. 2003). We conclude that the gas is heated
by either the cosmic rays from the nuclear starburst, or by the decay of turbulence within molecular clouds,
presumably also driven by the formation of stars. The heating of the molecular ISM by the starburst therefore is
inhibiting further episodes of star formation, so that for NGC 253 the starburst is self-limiting (Hailey-Dunsheath et al.
First Detections of the [CII] 158 um line from the Epoch of Enhanced Star Formation in the Universe
Detailed studies in the infrared to submillimeter continuum Over the past decade have shown that the rate of star formation per unit co-moving volume peaked when the Universe was only 15-45% of its present age (redshifts 1 to 3) at values 30 times the present rate. We have begun a program to study star formation in this epoch using the bright far-IR fine-structure lines as they are redshifted into the submm windows as probes. These lines are important coolants for most of the important phases of the interstellar medium, so that their measure yields important information on the star formation process on galactic scales.
The brightest of the far-IR lines (and indeed, it can be the brightest single line from a star forming galaxy) is the 158 um [CII] line which cools the cold neutral medium, the warm neutral medium, diffuse ionized gas and the photo-dissociation regions (PDRs) formed on the surfaces of molecular clouds exposed to the far-UV starlight from nearby OB stars and/or the general interstellar radiation field. Most of the [CII] line arises in PDRs (see link) where the gas is predominantly heated through the photo-electic ejection of electrons from grains, and cooled through its [CII] line radiation. About 1% of the far-UV energy flux heats the gas in this way, while most of the remainer heats the dust which cools via its far-IR continuum radiation. The [CII] line to far-IR continuum luminosity ratio, R is therefore a measure of the efficiency of the gas heating via the photo-electric effect. This efficiency is a strong function of the strength of the ambient interstellar radiation field, so to measure R is to measure those fields, i.e. the concentration of the starburst.
We have made the first detections of the [CII] 158 um line from star forming galaxies at redshifts between 1 and 2 - so that we can probe the physical parameters of the newly formed stars and their environs in the epoch of enhanced star formation in the Universe. At present, we have strongly detected emission from five systems including two submillmeter galaxies (SMGs), and two quasars. Many of the submillimeter galaxies are quite massive, and appear to be forming more than 1000 stars/year so that it could be these are the progenitors of modern day giant elliptical galaxies. We find the [CII] line is very luminous in all systems, and exceptionally bright in three of the galaxies, where the line flux amounts to more than 0.1% of the total far-IR continuum luminosity. CO rotational line emission has been detected from two of the three exceptionally bright [CII] line systems so that we can build a reasonably constrained model for the line emission regions. In a PDR scenario, the combination of [CII] and CO lines, together with the far-IR continuum constrain both the strength of the ambient interstellar radiation fields and the gas density. For MIPS J142824.0+352619 we find the far-UV radiation fields to be ~ 1000 times the local interstellar radiation field, and gas densities ~ 104cm-3 very similar to the conditions in the nearby starburst galaxy M82 (Hailey Dunsheath et al. 2009). The starburst in MIPS J14218 has similar physical conditions to that of M82, but is more than ~ 1000 times the luminosity! Combining our measure of the stellar radiation field strength with the total luminosity of the systems we can estimate the physical size of the starbursting regions. We find the starburst in MIPS J142824 is greatly extended, occupying a 4 kpc diameter region. This is in contrast to the local, lower luminosity ULIRG galaxes where the star forming regions are often spatially confined to regions ~ few hundred pc on a side. Something stimulates galaxy-wide starbursts in the epoch of maximum star formation for the Universe.
For the two quasars in our sample PKS0215+015 and PG1206+495, the [CII] line is relatively weak at only ~ 0.05% of the far-IR continuum luminosity. This
lowered ratio is expected, since a significant fraction of the far-IR continuum may arise from regions near the active nucleus
where UV radiation fields are exceptionally strong. The [CII] to far-IR continuum ratio is inversely proportional to the
strength of the ambient interstellar radiation field since strong fields will charge grains resulting in lessened efficiency
for photo-electric heating of the gas. Higher UV fields means less efficient gas heating, hence relatively lower [CII] cooling. The
far-IR continuum luminosity is not affected by the strength of the UV fields (essentially all of the far-UV goes into heating the dust), so that the net effect
is a smaller [CII] to far-IR continuum luminosity ratio.
First Detections of the CO(7-6), [CI] and CO(8-7) Line Emission from ULIRG Galaxies
Ultraluminous infrared galaxies (ULIRGs) are galaxies with luminosities in excess of 1012 Lsolar, whose luminosity is dominated by the far-IR emission from dust. Since their discovery, the source of their prodigious luminosity has been hotly debated. Are they powered by super-starbursts (> 100 Msolar/yr) or an active galactic nucleus (AGN)? We detect very bright mid-J CO line emission from ULIRG galaxies. Strong mid-J CO line emission is only produced in starbursts, so our results support starburst powered scenarios. Furthermore, we find a negative correlation between the luminosity of the CO(6-5) line and the far-IR continuum in the sense that ULIRG galaxies have smaller mid-J CO line to far-IR continuum ratios than starbursters. The observed fall-off can be explained through increased far-UV field strengths and cloud densities in ULIRG galaxies. Therefore, we find that star formation is both much more compact and much more vigorous in ULIRG galaxies than in lower luminosity systems.
For more information about the Caltech Submillimeter Observatory, visit
the CSO Homepage. | <urn:uuid:a58549cc-9565-4bbb-a305-a5b4cf240eae> | 2.6875 | 2,954 | Knowledge Article | Science & Tech. | 51.9464 |
|Galaxies, Stars, and Dust|
Spiky stars and spooky shapes abound in
deep cosmic skyscape.
Its well-composed field of view covers
about 2 Full Moons on the
sky toward the constellation Pegasus.
Of course the brighter stars show diffraction spikes, the commonly
seen effect of internal
in reflecting telescopes, and lie
well within our own Milky Way galaxy.
The faint but pervasive clouds of interstellar dust
ride above the galactic plane and dimly reflect the
Known as high latitude cirrus or integrated flux nebulae they are
associated with molecular clouds.
In this case, the diffuse cloud cataloged as
less than a thousand light-years distant, fills the scene.
Other galaxies far beyond the Milky Way are visible through the
ghostly apparitions, including the striking spiral galaxy NGC 7497
some 60 million light-years away.
Seen almost edge-on
near the center of the field,
NGC 7497's own spiral arms and dust lanes echo the colors of the
Milky Way's stars and dust.
Ignacio de la Cueva Torregrosa | <urn:uuid:553c8415-342d-4a60-930a-2156b4472a48> | 3.140625 | 237 | Content Listing | Science & Tech. | 46.169053 |
Air-conditioned ants: The secret behind their vast underground cities... ventilation
They are known for their industrious nature. But the humble ant's sophisticated home-making skills has left some of the brightest scientific minds in awe of the tiny creatures.
Researchers have discovered the vast underground colonies where up to seven million of the insects live have their very own in-built ventilation shafts.
It is thought the 'air-conditioning' helps ants tend to a delicately-balanced fungal garden that feeds their young.
Scroll down for video
Hard workers: Underground ant colonies are so complex, they even have ventilation shafts
For years scientists have been at a loss as to how the industrious ants were able to keep their nests at just the right temperature to allow the fungus to grow... until now.
New research has shown that the insects make specially-constructed turrets which ventilate the nests for optimum growth.
According to a study published in the
Journal of Insect Behaviour, the ants carefully create the turrets with
highly porous walls which allows air to flow through the chambers.
It was already known that ant constructed the turrets, but this study is the first to reveal how they do it, it has been reported.
Sophisticated: Scientists could not work out how the ants built nests that stayed at the right temperature... until now
A team of researchers took a colony of grass-cutting ants into the lab to test their nest-building techniques with a range of different materials.
The ants were given clay, coarse sand and fine sand, with scientists regularly changing the quantity of the material and pouring water over them to simulate rain, according to the BBC.
Leading the study, Dr Marcela Cosarinksy, from Buenos Aires' Agentinian Museum of Natural Science told the BBC: 'When [the ants] finished a turret, we analysed the arrangement of the building materials [under] the microscope.
'The ants construct the turrets by stacking sand grains and little balls of clay that they mould with their [jaws].'
When pores collapsed under water, the walls would compact - and immediately the worker ants removed the materials and re-worked the turret wall.
The scientists said the research confirmed that ventilation turrets were 'built structures' as opposed to passive deposition of excavated soil, a technique used by other ant species. | <urn:uuid:0c1694c8-6d04-4dae-bc56-f75f8f08481d> | 2.71875 | 484 | Truncated | Science & Tech. | 50.846248 |
Andromeda Galaxy, cataloged as M31 and NGC 224, the closest large galaxy to the Milky Way and the only one visible to the naked eye in the Northern Hemisphere. It is also known as the Great Nebula in Andromeda. It is 2.2 million light-years away and is part of the Local Group of several galaxies that includes the Milky Way, which it largely resembles in shape and composition, although the Milky Way is a barred spiral galaxy and Andromeda is a spiral galaxy. It has a diameter of about 165,000 light-years and contains at least 200 billion stars. Its two brightest companion galaxies are M32 and M110. The light arriving at earth from the Andromeda Galaxy is shifted toward the blue end of the spectrum, whereas the light from all other cosmic sources exhibits red shift.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
More on Andromeda Galaxy from Fact Monster:
See more Encyclopedia articles on: Astronomy: General | <urn:uuid:8a5c0509-b46a-4cad-a8c5-3f71fe47017a> | 3.609375 | 203 | Knowledge Article | Science & Tech. | 49.286571 |
New Mexico's Gila National Forest is a good natural laboratory for studying the effects of wildfire.
by Neil LaRubbio,
Nov 14, 2012
Controversial new studies question the conventional wisdom on Western ponderosa forests and the severity of their historic wildfires.
by Emily Guerin,
Sep 26, 2012
The backstory to Emily Guerin's report on the scientific debate over how "normal" severe fire is, and a travelogue from the Gila Wilderness in the wake of this year's massive blaze.
by Cally Carswell, Emily Guerin, Neil LaRubbio,
Sep 25, 2012
It's hard for journalists to talk about climate change, but they need to keep telling the story, especially when writing about natural disasters.
by Allen Best,
Jul 25, 2012
A New Mexican watches Whitewater-Baldy fire burn the Gila National Forest, and even as it changes a place she loves, her ecologist self cheers it on.
by Martha Schumann Cooper,
Jun 14, 2012
President Bush says the Healthy Forests Restoration Act
and Initiative were needed to fight wildfire, but several years
into the new rules, critics question whether the changes they
brought were helpful or even necessary
by Kathie Durbin,
Apr 17, 2006
This season’s wildfires are caused by three things: Climate change-induced
drought, bureaucratic blindness and old-fashioned human folly.
by William deBuys,
Jun 30, 2011
The aftermath of Boulder's destructive Fourmile Canyon fire.
by Cally Carswell,
Sep 26, 2010
Pepper Trail, a wildlife biologist in Oregon, says that
this is not the time to log our way out of wildfire threats in the
by Pepper Trail,
Aug 11, 2003
Public officials – and even homeowners – are beginning to accept the inevitability of wildfires in the Golden State.
by Peter Friederici ,
Jun 05, 2009 | <urn:uuid:aedd7621-9cad-4728-a9b6-827020b11f21> | 2.71875 | 409 | Content Listing | Science & Tech. | 31.0575 |
1. What is ASP.NET AJAX?
ASP.NET AJAX, mostly called AJAX, is a set of extensions of ASP.NET. It is developed by Microsoft to implement AJAX functionalities in Web applications. ASP.NET AJAX provides a set of components that enable the developers to develop applications that can update only a specified portion of data without refreshing the entire page. The ASP.NET AJAX works with the AJAX Library that uses object-oriented programming (OOP) to develop rich Web applications that communicate with the server using asynchronous postback.
2. What is the difference between synchronous postback and asynchronous postback?
The difference between synchronous and asynchronous postback is as follows:
3. What technologies are being used in AJAX?
AJAX uses four technologies, which are as follows:
4. Why do we use the XMLHttpRequest object in AJAX?
5. How can we get the state of the requested process?
XMLHttpRequest get the current state of the request operation by using the readyState property. This property checks the state of the object to determine if any action should be taken. The readyState property uses numeric values to represent the state.
6. What are the different controls of ASP.NET AJAX?
ASP.NET AJAX includes the following controls: | <urn:uuid:e5aa2be3-f5c5-43c6-87a4-a92df97818de> | 2.953125 | 279 | Q&A Forum | Software Dev. | 48.747624 |
The Gather Procedure takes an input vector that is distributed across all the processors and gathers it into another distributed vector or array according to an indirect index vector or array. No collisions are possible, since this call is effectively pulling values out of a distributed variable, and there is a different location for each pulled value. This is the opposite of the Scatter procedure.
|call Gather (Output, Input, Index, Trace)|
|Index||An optional integer vector or array of indirect references to positions in the Input vector. This must be included on the first call to this procedure with a given data structure, but may be omitted on subsequent calls if the Trace variable is present. [Optional]|
|Input||A real, integer or logical vector that is distributed across all the processors.|
|Trace||An optional structure that stores the setup from a previous Gather/Scatter call using the same Index variable and Input vector length. If Trace is present and uninitialized, it is set by this procedure. If Trace is present, it is used regardless of whether Index is present.|
|Output||The gathered version of the Input vector, distributed across the processors.|
|Trace||If present, Trace is set to the setup information for this Gather/Scatter. [Optional]|
The Gather code listing contains additional documentation.
Michael L. Hall | <urn:uuid:34b94f2c-3aee-4c6c-8ddf-632c954bbfdb> | 3.09375 | 283 | Documentation | Software Dev. | 34.478718 |
Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
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hypotenuse is 20 inches one of the legs are 16 inches what is the measure of the other leg. i got 12 but i dont think its right
is there anyone who can help me like asap
Take the square root of both sides,
So AB = 1.4422205101 cm.
Do you know how to round that to the nearest hundredth?
I don't know if I can explain my question properly but if someone understands please help!! Ok so the directions say Find the length of AB to the nearest hundredth centimeter. All measurements are in centimeters, but figures may be drawn to different scales. Explain your reasoning.
okay so i have a triangle with a side of 230m and 150m, what is the missing length?
help me to thanks
[Incorrect, and rude, comment removed by moderator] | <urn:uuid:54a5acf3-13c3-4238-a873-d55ffaea6881> | 3.015625 | 252 | Comment Section | Science & Tech. | 76.086938 |
I was thinking about the 90° angle between the x, y, and z-axis.
It is all so perfect. So I said you need two independent real
numbers (cooridinates) to describe a point in a plane. Then I
thought about putting the x and y axis at a 10° angle instead of
90°, and noticed you could still get to all the points on the plane.
Next I attempted to find a way to describe all the points on a plane
with only 1 number. Is it possible? So at first I played around with
the idea of a spiral that was so close together at each pass around that
it would take infinite times to make up some area, but this idea soon
I decided was dumb and incomprehensible. Then I came up with a
plausible idea, if you don't mind a jumbled mess in place of two nice
x and y axis. So this is only a first try at this and I hope to come up
with refined examples that use negative numbers as well as decimals
later, but for now I am only using whole numbers. I started at (-1,1)
and called this 1. Then (0,1) would be 2. Here is a chart.
(x,y) 1-D number
At this point we expand the grid larger by factor of ten and make the intervals
smaller by a factor of ten. So we continue. Some duplicate points will exist
as we go over the previous ones.
This continues to the right until we hit 10,10 and
then the rows continue down to form a square grid.
Then we will be at approximately the number 201 * 201 + 9.
Next we again expand the grid ten times larger and ten times more intricate.
etc. etc. You get the picture.
Does anybody think it is interesting??
Do you think by going to infinity, you will pass through both a large surface area
and work toward getting more intricate as well?
Obviously it is a jumbled mess, but if you ignore the mess, it is pretty cool,
hence in the "This is Cool" category. | <urn:uuid:d15ae821-475c-4685-ae49-06475635037e> | 3.046875 | 451 | Comment Section | Science & Tech. | 75.749203 |
Introns in promoterhow is it possible?
Posted 15 May 2012 - 09:38 PM
Posted 09 June 2012 - 08:21 AM
Posted 09 August 2012 - 01:53 AM
Eukaryotes promoters are quite complex and some binding sites for proteins that activate the transcription may actually be downstream of the mRNA start position, or it may be that the presensce of the first intron/exon increases the promoters activity and is therefore considered part of the promoter region. Many of the strongest mammalian promoters have introns in them, Ubiquitin, Elongation factor alpha and chicken beta actin (full length) all have introns in them. In fact, many people add an intron upstream of their gene to prolong expression in vivo. It makes a gene more like a natural gene and decreases its chances of being methylated. | <urn:uuid:36db8c5a-6e12-44c5-98fa-990808870102> | 2.78125 | 174 | Q&A Forum | Science & Tech. | 42.440511 |
Feb. 23, 2010 Regulatory proteins common to all eukaryotic cells can have additional, unique functions in embryonic stem (ES) cells, according to a study in the February 22 issue of the Journal of Cell Biology. If cancer progenitor cells -- which function similarly to stem cells -- are shown to rely on these regulatory proteins in the same way, it may be possible to target them therapeutically without harming healthy neighboring cells.
The new study, by Thomas Fazzio and Barbara Panning (University of California, San Francisco) finds that two chromatin regulatory proteins essential for ES cell survival, Smc2 and Smc4, together form the heart of the condensin complexes that promote chromosome condensation in mitosis and meiosis. Because somatic cells lacking condensins continue to proliferate with relatively minor mitotic defects, Fazzio and Panning wondered why ES cells died in the absence of Smc2 or Smc4.
ES cells lacking the condensin subunits accrued massive amounts of DNA damage that resulted in cell death. It isn't clear why ES cells are so sensitive to the loss of condensins, but it may be connected to two other phenotypes seen in ES, but not somatic, cells. After Smc2 or Smc4 was blocked, mitotic ES cells arrested in metaphase and interphase ES cell nuclei were enlarged and misshapen.
This suggests that condensins promote mitotic progression and maintain interphase chromatin compaction in ES cells -- functions that they don't have in somatic cells. In fact, many other chromatin regulatory proteins involved in ES cell survival can be depleted in differentiated cells without affecting viability, indicating that the chromatin of ES cells -- and possibly cancer progenitor cells -- is fundamentally different from somatic cell chromatin.
Reference: Fazzio, T.G., and B. Panning. 2010. J. Cell Biol. doi:10.1083/jcb.200908026.
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Note: If no author is given, the source is cited instead. | <urn:uuid:69378649-eec1-4c2d-baff-7f0e547e8514> | 2.703125 | 437 | Truncated | Science & Tech. | 42.799632 |
Web edition: August 27, 2012
Though ancient Egyptians are famous for their mummies, Americans — South Americans — practiced the preservation method first. In a desert coastal region of what is now northern Chile and southern Peru, the Chinchorro people began mummifying their dead about 7,000 years ago. Now scientists have proposed an explanation for how this practice got its start: The Chinchorro were just copying nature.
B. Bower. Good times led to grisly custom. Science News Online, August 13, 2012. [Go to] | <urn:uuid:9c4a68b9-8d79-4ead-b464-5115745c1929> | 3.21875 | 115 | Truncated | Science & Tech. | 56.69622 |
Discovered: A camera that can see around corners, why we don't eat smelly foods, the super-Earth is not so super, noise pollution is also bad for plants and abnormal brain development might determine personality.
- This camera takes pictures of things it never saw. Remember that camera that could capture the speed of light we learned all about last December? The brains at the MIT media lab intended on using that technology for a camera that can see around corners. And, they have accomplished just that, creating a contraption that captures images of things around corners. It works like a periscope but instead of using reflective surfaces it uses walls, doors and floors -- things that do not reflect light. That sounds like straight-up magic to us. But, this video claims it's just science being science. [MIT Media Lab]
- Why we don't eat smelly foods. We didn't realize that not eating smelly foods was a thing, because we quite like smelly foods. But science says it's a thing and has also discovered the reason behind the aversion. Our brains and taste-buds tell us to take smaller bites of things with strong aromas because the smaller bites make us taste the food less than bigger ones. "Perhaps, in keeping with the idea that smaller bites are associated with lower flavour sensations from the food and that, there is an unconscious feedback loop using bite size to regulate the amount of flavour experienced," explains researcher Rene A de Wijk. All of this, one day, could be used as some sort of dieting scheme. [BioMed Central Limited]
- The Super Earth is not so super. That new "possibly habitable" Super-Earth science got all excited about isn't all that after all. (Go, original Earth!) It can maybe still support life, because liquid water could possible exist there -- it's all very dubious. One thing is for sure, though. The planet could never transfer life to another one of its solar-system neighbors. "Planet d would have a very small chance of transferring material to the other planets in the Gliese system and, thus, is far more isolated, biologically, than the inner planets of our own solar system," explained researcher Laci Brock . "It really shows us how unique our solar system is." So, should we start calling it not-so-Super-Earth now? [Lunar and Planetary Science]
- Noise pollution is also bad for plants. It makes sense that human noises would scare and probably harm animals, but plants? Science says yes. The animals react to the noise, and thus have different pollination and eating habits. The whole thing has an unintended consequences domino effect thing going on because once the plants change then the whole eco-system changes, attracting different types of animals. [National Evolutionary Synthesis Center]
- If you have this type of personality you might have a brain defect. Are you both gregarious and anxious? (Yes ... ) Well it might have something to do with abnormal brain development, which cause a disease called Williams Syndrome, finds research out of NIH. "Scans of the brain's tissue composition, wiring, and activity produced converging evidence of genetically-caused abnormalities in the structure and function of the front part of the insula and in its connectivity to other brain areas in the circuit," explains researcher Karen Berman. [Proceedings of the National Academy of Sciences] | <urn:uuid:fc1ab892-d078-42ea-a18f-51e101ad2a45> | 2.875 | 699 | Listicle | Science & Tech. | 50.459687 |
2010 is the International Year of Biodiversity. Why should you care?
Biodiversity is the number of different species that exist in a given area. The healthier an area is, the more biodiversity it has. Different forms of wildlife and plants inhabit areas, and these plants and animals learn to coexist and form ecological relationships with each other.
In unhealthy environments, only a few kinds of species of each plant or animal exist. This is what is known as a monoculture, and monocultures are unhealthy. Whether a monoculture is ten thousand or a hundred thousand acres planted all together of one kind of crop, or an entire subdivision with lawns all growing the same five plants, monocultures are vulnerable to pests and disease. For example, part of the fire ant problem in the United States is exacerbated by homeowners, because fire ants prefer monocultures and will shy away from biodiverse areas.
By contrast, the more kinds of species that inhabit an area, the more likely it is that at least a few strains of plants or animals will be resistant to pests and disease. If you have thirty kinds of plants, and a virus blows in across the ocean from a remote island, your lawn has a better chance of surviving and renewing itself than if you have only five kinds of plants. In the same way, having more species of wild birds will provide more secure insect control than having only a few kinds of wild birds. So, by growing more kinds of plants in your yard, you will attract more animals, and help to increase your neighbourhood’s biodiversity. | <urn:uuid:5a91c161-3285-41c8-8469-edeb3b85a206> | 3.4375 | 325 | Listicle | Science & Tech. | 44.127564 |
Tag Archives: biology
New USGS research shows that rice could become adapted to climate change and some catastrophic events by colonizing its seeds or plants with the spores of tiny naturally occurring fungi. The DNA of the rice plant itself is not changed; instead, researchers are re-creating what normally happens in nature.
USGS science supports management, conservation, and restoration of imperiled, at-risk, and endangered species.
New USGS research shows that certain lichens can break down the infectious proteins responsible for chronic wasting disease, a troubling neurological disease fatal to wild deer and elk and spreading throughout the United States and Canada.
For reliable information about amphibians and the environmental factors that are important to their management and conservation, visit the new USGS Amphibian Monitoring and Research Initiative website.
Efforts are underway to restore the Greater Everglades Ecosystem, which has been profoundly altered by development and water management practices. Join us on December 1st when Dr. Lynn Wingard shares USGS research that is helping restoration management agencies develop realistic and attainable restoration goals for the region.
Two new tools that enable the public to report sick or dead wild animals could also lead to the detection and containment of wildlife disease outbreaks that may pose a health risk to people.
The timing of animal migration and reproduction, and observing when plants send out new leaves and bear fruit, is increasingly important in understanding how climate change affects biological and hydrologic systems. Photo credit Copyright C Brandon Cole.
The USGS has been researching manatees in Florida and the Caribbean for decades, but little is known about Cuban manatees. A USGS biologist recently visited Cuba with a team of international manatee experts working to conserve manatees around the Caribbean.
USGS scientists have discovered a new turtle species, the Pearl River map turtle, found only in the Pearl River in Louisiana and Mississippi. Sea-level changes between glacial and interglacial periods over 10,000 years ago isolated the map turtles, causing them to evolve into unique species. | <urn:uuid:7b99ffe4-a450-4492-84cc-d927dcfb00b0> | 3 | 416 | Content Listing | Science & Tech. | 24.563085 |
I am all for creative thinking, but this may be the oddest concept I've yet seen to treat one of the symptoms of global warming.
Going far beyond just tracking melting patterns, German researchers want to actually stop, or at least slow down the melting of glaciers in the Swiss Alps, and they plan to do so by setting up a large screen that would trap cold air over the ice. The experimental screen is nearly 50 feet long by 10 feet high, and was set up in the middle of the Rhone glacier in
Ooooh kay. This may be one of those science-for-the-environment-gone-off-track moments. I have a very hard time imagining that this idea will go very far in keeping glaciers from melting, but at least they're trying. Filed under “Weird.”
written by Krazd, August 16, 2008
written by bobbknight, August 17, 2008
written by ETC, August 17, 2008
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Science Fair Project Encyclopedia
Alforsite is a mineral, Ba5Cl(PO4)3, composed of barium, phosphorus, chlorine, and oxygen. It was discovered in 1981, and named to honor geologist John T. Alfors of the California Division of Mines and Geology for his work in the area where it was discovered.
Alforsite is a hexagonal colorless crystal in the chemical class phosphates and the group apatite. It is found in certain parts of central California, primarily Fresno, Mariposa, and Tulare Counties. It has also been found in Baja California, Mexico.
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details | <urn:uuid:87625e32-2f02-4652-9a3a-dec87e67ccf6> | 3.71875 | 162 | Knowledge Article | Science & Tech. | 37.907295 |