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47
2023-07-12
Exponential stability of damped Euler-Bernoulli beam controlled by boundary springs and dampers
In this paper, the vibration model of an elastic beam, governed by the damped Euler-Bernoulli equation $\rho(x)u_{tt}+\mu(x)u_{t}$$+\left(r(x)u_{xx}\right)_{xx}=0$, subject to the clamped boundary conditions $u(0,t)=u_x(0,t)=0$ at $x=0$, and the boundary conditions $\left(-r(x)u_{xx}\right)_{x=\ell}=k_r u_x(\ell,t)+k_a...
2307.06170v2
2023-08-03
Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model
We propose a theoretical framework to investigate elementary excitations at finite temperatures within a localized electron model that describes the interactions between multiple degrees of freedom, such as quantum spin models and Kugel-Khomskii models. Thus far, their excitation structures have been mainly examined us...
2308.01711v1
2024-02-13
Investigating the Effect of Noise on the Training Performance of Hybrid Quantum Neural Networks
In this paper, we conduct a comprehensively analyze the influence of different quantum noise gates, including Phase Flip, Bit Flip, Phase Damping, Amplitude Damping, and the Depolarizing Channel, on the performance of HyQNNs. Our results reveal distinct and significant effects on HyQNNs training and validation accuraci...
2402.08523v1
2024-03-03
Magnonic $\varphi$ Josephson Junctions and Synchronized Precession
There has been a growing interest in non-Hermitian physics. One of its main goals is to engineer dissipation and to explore ensuing functionality. In magnonics, the effect of dissipation due to local damping on magnon transport has been explored. However, the effects of non-local damping on the magnonic analog of the J...
2403.01625v1
1997-01-17
Evidence for Rotation in the Galaxy at z=3.15 Responsible for a Damped Lyman-alpha Absorption System in the Spectrum of Q2233+1310
Proof of the existence of a significant population of normal disk galaxies at redshift z>2 would have profound implications for theories of structure formation and evolution. We present evidence based on Keck HIRES observations that the damped Lyman-alpha absorber at z=3.15 toward the quasar Q2233+1310 may well be such...
9701116v2
1997-04-11
The Metallicity of High Redshift Galaxies: The Abundance of Zinc in 34 Damped Lyman Alpha Systems from z = 0.7 to 3.4
We report new observations of ZnII and CrII absorption lines in 10 damped \lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining these results with those from our earlier survey (Pettini et al. 1994) and other recent data, we construct a sample of 34 measurements (or upper limits) of the Zn abundan...
9704102v1
1997-04-17
On the Kinematics of the Damped Lyman Alpha Protogalaxies
We present the first results of an ongoing program to investigate the kinematic characteristics of high redshift damped lya systems. Because damped lya systems are widely believed to be the progenitors of current massive galaxies, an analysis of their kinematic history allows a direct test of galaxy formation scenarios...
9704169v2
2000-11-20
H-alpha Imaging with HST+NICMOS of An Elusive Damped Ly-alpha Cloud at z=0.6
Despite previous intensive ground-based imaging and spectroscopic campaigns and wide-band HST imaging of the z=0.927 QSO 3C336 field, the galaxy that hosts the damped Ly-alpha system along this line-of-sight has eluded detection. We present a deep narrow-band H-alpha image of the field of this z=0.656 damped Ly-alpha a...
0011374v2
2005-08-17
The SDSS Damped Lya Survey: Data Release 3
We present the results from a damped Lya survey of the Sloan Digital Sky Survey, Data Release 3 based on over 500 new damped Lya systems at z>2.2. We measure the HI column density distribution f(N) and its zeroth and first moments (the incidence l(X) and gas mass-density O_dla of damped Lya systems, respectively) as a ...
0508361v1
2010-03-11
Damping of MHD turbulence in partially ionized gas and the observed difference of velocities of neutrals and ions
Theoretical and observational studies on the turbulence of the interstellar medium developed fast in the past decades. The theory of supersonic magnetized turbulence, as well as the understanding of projection effects of observed quantities, are still in progress. In this work we explore the characterization of the tur...
1003.2346v1
2011-09-07
Weakly collisional Landau damping and three-dimensional Bernstein-Greene-Kruskal modes: New results on old problems
Landau damping and Bernstein-Greene-Kruskal (BGK) modes are among the most fundamental concepts in plasma physics. While the former describes the surprising damping of linear plasma waves in a collisionless plasma, the latter describes exact undamped nonlinear solutions of the Vlasov equation. There does exist a relati...
1109.1353v1
2012-11-06
Torsional Alfvén waves in solar partially ionized plasma: effects of neutral helium and stratification
Ion-neutral collisions may lead to the damping of Alfven waves in chromospheric and prominence plasmas. Neutral helium atoms enhance the damping in certain temperature interval, where the ratio of neutral helium and neutral hydrogen atoms is increased. Therefore, the height-dependence of ionization degrees of hydrogen ...
1211.1348v2
2013-05-16
Application of vibration-transit theory to distinct dynamic response for a monatomic liquid
We examine the distinct part of the density autocorrelation function Fd(q,t), also called the intermediate scattering function, from the point of view of the vibration-transit (V-T) theory of monatomic liquid dynamics. A similar study has been reported for the self part, and we study the self and distinct parts separat...
1305.3954v2
2013-09-16
Two-atom system as a nano-antenna for mode switching and light routing
We determine how a system composed of two nonidentical two-level atoms with different resonance frequencies and different damping rates could work as a nano-antenna for controlled mode switching and light routing. We calculate the angular distribution of the emitted field detected in a far-field zone of the system incl...
1309.3924v1
2015-04-01
Landau damping of Gardner solitons in a dusty bi-ion plasma
The effects of linear Landau damping on the nonlinear propagation of dust-acoustic solitary waves (DASWs) are studied in a collisionless unmagnetized dusty plasma with two species of positive ions. The extremely massive, micron-seized, cold and negatively charged dust particles are described by fluid equations, whereas...
1504.00089v2
2017-07-18
Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios
Many studies have shown that either the nearby astrophysical source or dark matter (DM) annihilation/decay is required to explain the origin of high energy cosmic ray (CR) $e^\pm$, which are measured by many experiments, such as PAMELA and AMS-02. Recently, the Dark Matter Particle Explorer (DAMPE) collaboration has re...
1707.05664v2
2018-06-27
In-flight performance of the DAMPE silicon tracker
DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray and gamma-ray detector, successfully launched in December 2015. It is designed to probe astroparticle physics in the broad energy range from few GeV to 100 TeV. The scientific goals of DAMPE include the identification of possible signatures of...
1806.10355v1
2018-10-30
Effect of Landau damping on ion acoustic solitary waves in a multi-species collisionless unmagnetized plasma consisting of nonthermal and isothermal electrons
A Korteweg-de Vries (KdV) equation including the effect of Landau damping is derived to study the propagation of weakly nonlinear and weakly dispersive ion acoustic waves in a collisionless unmagnetized plasma consisting of warm adiabatic ions and two different species of electrons at different temperatures. The hotter...
1810.12739v1
2019-03-28
Improving convergence of volume penalised fluid-solid interactions
We analyse and improve the volume-penalty method, a simple and versatile way to model objects in fluid flows. The volume-penalty method is a kind of fictitious-domain method that approximates no-slip boundary conditions with rapid linear damping inside the object. The method can then simulate complex, moving objects in...
1903.11914v4
2019-06-12
Study of Alfven Eigenmodes stability in plasma with multiple NBI driven energetic particle specie
The aim of this study is to analyze the destabilization of Alfven Eigenmodes (AE) by multiple energetic particles (EP) species in DIII-D and LHD discharges. We use the reduced MHD equations to describe the linear evolution of the poloidal flux and the toroidal component of the vorticity in a full 3D system, coupled wit...
1906.05701v1
2019-11-05
Observation of Nanoscale Opto-Mechanical Molecular Damping; Origin of Spectroscopic Contrast in Photo Induced Force Microscopy
We experimentally investigated the contrast mechanism of infrared photoinduced force microscopy (PiFM) for recording vibrational resonances. Extensive experiments have demonstrated that spectroscopic contrast in PiFM is mediated by opto-mechanical damping of the cantilever oscillation as the optical wavelength is scann...
1911.05190v1
2020-06-08
Stochastic re-acceleration and magnetic-field damping in Tycho's supernova remnant
A number of studies suggest that shock acceleration with particle feedback and very efficient magnetic-field amplification combined with Alfv\'{e}nic drift are needed to explain the rather soft radio spectrum and the narrow rims observed for Tycho's SNR. We show that the broadband spectrum of Tycho's SNR can alternativ...
2006.04832v1
2021-02-23
Influence of Ion-Neutral Damping on the Cosmic-Ray Streaming Instability: Magnetohydrodynamic Particle-in-cell Simulations
We explore the physics of the gyro-resonant cosmic ray streaming instability (CRSI) including the effects of ion-neutral (IN) damping. This is the main damping mechanism in (partially-ionized) atomic and molecular gas, which are the primary components of the interstellar medium (ISM) by mass. Limitation of CRSI by IN d...
2102.11878v3
2022-06-17
Quantum Dynamics of Magnetic Skyrmions: Consistent Path Integral Formulation
We present a path integral formalism for the intrinsic quantum dynamics of magnetic skyrmions coupled to a thermal background of magnetic fluctuations. Upon promoting the skyrmion's collective coordinate $\boldsymbol{R}$ to a dynamic variable and integrating out the magnonic heat bath, we derive the generalized equatio...
2206.08532v2
2024-02-05
Revisiting the role of cosmic-ray driven Alfvén waves in pre-existing magnetohydrodynamic turbulence. I. Turbulent damping rates and feedback on background fluctuations
Alfv\'en waves (AWs) excited by the cosmic-ray (CR) streaming instability (CRSI) are a fundamental ingredient for CR confinement. The effectiveness of self-confinement relies on a balance between CRSI growth rate and damping mechanisms acting on quasi-parallel AWs excited by CRs. One relevant mechanism is the so-called...
2402.02901v1
2006-10-24
Logical contradictions of Landau damping
Landau damping/growing at boundary condition of excitation of a harmonic wave in collisionless ion-electron-neutrals plasma contradicts to the law of energy conservation of a wave damping/growing in space. There is also no criterion of a choice either damping or growing solution in difference from always non-damping in...
0610220v67
1999-12-17
Infrared Spectroscopy of a Massive Obscured Star Cluster in the Antennae Galaxies (NGC 4038/4039) with NIRSPEC
We present infrared spectroscopy of the Antennae Galaxies (NGC 4038/4039) with NIRSPEC at the W. M. Keck Observatory. We imaged the star clusters in the vicinity of the southern nucleus (NGC 4039) in 0.39" seeing in K-band using NIRSPEC's slit-viewing camera. The brightest star cluster revealed in the near-IR (M_K(0) =...
9912369v1
2000-09-07
Practical Quantum Cryptography: A Comprehensive Analysis (Part One)
We perform a comprehensive analysis of practical quantum cryptography (QC) systems implemented in actual physical environments via either free-space or fiber-optic cable quantum channels for ground-ground, ground-satellite, air-satellite and satellite-satellite links. (1) We obtain universal expressions for the effecti...
0009027v5
2009-08-07
The Dominance of Metal-Rich Streams in Stellar Halos: A Comparison Between Substructure in M31 and Lambda-CDM Models
Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS spectrog...
0908.1111v1
2009-09-25
The SPLASH Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream
The giant southern stream (GSS) is the most prominent tidal debris feature in M31's stellar halo. The GSS is composed of a relatively metal-rich, high surface-brightness "core" and a lower metallicity, lower surface brightness "envelope." We present Keck/DEIMOS spectroscopy of red giant stars in six fields in the vicin...
0909.4540v1
2011-05-28
Transmission Control of Two-User Slotted ALOHA Over Gilbert-Elliott Channel: Stability and Delay Analysis
In this paper, we consider the problem of calculating the stability region and average delay of two user slotted ALOHA over a Gilbert-Elliott channel, where users have channel state information and adapt their transmission probabilities according to the channel state. Each channel has two states, namely, the 'good' and...
1105.5676v2
2012-10-11
Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile
We present the surface brightness profile of M31's stellar halo out to a projected radius of 175 kpc. The surface brightness estimates are based on confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS spectroscopic observations. A set of empirical spectroscopic and photometric M31 membership diagnos...
1210.3362v2
2014-09-12
Global Properties of M31's Stellar Halo from the SPLASH Survey: II. Metallicity Profile
We present the metallicity distribution of red giant branch (RGB) stars in M31's stellar halo, derived from photometric metallicity estimates for over 1500 spectroscopically confirmed RGB halo stars. The stellar sample comes from 38 halo fields observed with the Keck/DEIMOS spectrograph, ranging from 9 to 175 kpc in pr...
1409.3843v1
2016-07-15
Solving the stochastic Landau-Lifshitz-Gilbert-Slonczewski equation for monodomain nanomagnets : A survey and analysis of numerical techniques
The stochastic Landau-Lifshitz-Gilbert-Slonczewski (s-LLGS) equation is widely used to study the temporal evolution of the macrospin subject to spin torque and thermal noise. The numerical simulation of the s-LLGS equation requires an appropriate choice of stochastic calculus and numerical integration scheme. In this p...
1607.04596v4
2016-11-30
Low Energy Supergravity Revisited (I)
General forms of the K\"ahler and superpotenials that lead to consistent low energy broken Supersymmetry originating from $N=1$ Supergravity have been classified and used for model building since more than three decades. We point out the incompleteness of this classification when hidden sector vacuum expectation values...
1611.10327v2
2018-08-08
Analysis of quasi-Monte Carlo methods for elliptic eigenvalue problems with stochastic coefficients
We consider the forward problem of uncertainty quantification for the generalised Dirichlet eigenvalue problem for a coercive second order partial differential operator with random coefficients, motivated by problems in structural mechanics, photonic crystals and neutron diffusion. The PDE coefficients are assumed to b...
1808.02639v3
2018-09-24
Ionic Tuning of Cobaltites at the Nanoscale
Control of materials through custom design of ionic distributions represents a powerful new approach to develop future technologies ranging from spintronic logic and memory devices to energy storage. Perovskites have shown particular promise for ionic devices due to their high ion mobility and sensitivity to chemical s...
1809.08728v1
2019-04-10
The Convergence of Iterative Delegations in Liquid Democracy in a Social Network
Liquid democracy is a collective decision making paradigm which lies between direct and representative democracy. One of its main features is that voters can delegate their votes in a transitive manner such that: A delegates to B and B delegates to C leads to A indirectly delegates to C. These delegations can be effect...
1904.05775v2
2019-06-20
Ongoing Vaccine and Monoclonal Antibody HIV Prevention Efficacy Trials and Considerations for Sequel Efficacy Trial Designs
Four randomized placebo-controlled efficacy trials of a candidate vaccine or passively infused monoclonal antibody for prevention of HIV-1 infection are underway (HVTN 702 in South African men and women; HVTN 705 in sub-Saharan African women; HVTN 703/HPTN 081 in sub-Saharan African women; HVTN 704/HPTN 085 in U.S., Pe...
1906.08409v1
2019-08-12
Elemental Abundances in M31: First Alpha and Iron Abundance Measurements in M31's Giant Stellar Stream
We present the first measurements of [Fe/H] and [$\alpha$/Fe] abundances, obtained using spectral synthesis modeling, for red giant branch stars in M31's giant stellar stream. The spectroscopic observations, obtained at a projected distance of 17 kpc from M31's center, yielded 61 stars with [Fe/H] measurements, includi...
1908.04429v1
2019-08-21
Generalized Metric Repair on Graphs
Many modern data analysis algorithms either assume or are considerably more efficient if the distances between the data points satisfy a metric. These algorithms include metric learning, clustering, and dimension reduction. As real data sets are noisy, distances often fail to satisfy a metric. For this reason, Gilbert ...
1908.08411v1
2019-09-19
Parameterized Complexity of Manipulating Sequential Allocation
The sequential allocation protocol is a simple and popular mechanism to allocate indivisible goods, in which the agents take turns to pick the items according to a predefined sequence. While this protocol is not strategy-proof, it has been shown recently that finding a successful manipulation for an agent is an NP-hard...
1909.08920v4
2019-11-06
Doppler Spectrum Classification with CNNs via Heatmap Location Encoding and a Multi-head Output Layer
Spectral Doppler measurements are an important part of the standard echocardiographic examination. These measurements give important insight into myocardial motion and blood flow providing clinicians with parameters for diagnostic decision making. Many of these measurements can currently be performed automatically with...
1911.02407v2
2020-01-02
The Effect of Treatment-Related Deaths and "Sticky" Diagnoses on Recorded Prostate Cancer Mortality
Background: Although recorded cancer mortality should include both deaths from cancer and deaths from cancer treatment, there is evidence suggesting that the measure may be incomplete. To investigate the completeness of recorded prostate cancer mortality, we compared other-cause (non-prostate cancer) mortality in men f...
2001.00492v1
2020-06-09
Elemental Abundances in M31: Iron and Alpha Element Abundances in M31's Outer Halo
We present [Fe/H] and [$\alpha$/Fe] abundances, derived using spectral synthesis techniques, for stars in M31's outer stellar halo. The 21 [Fe/H] measurements and 7 [$\alpha$/Fe] measurements are drawn from fields ranging from 43 to 165 kpc in projected distance from M31. We combine our measurements with existing liter...
2006.05430v1
2020-11-11
Unique Decoding of Explicit $ε$-balanced Codes Near the Gilbert-Varshamov Bound
The Gilbert-Varshamov bound (non-constructively) establishes the existence of binary codes of distance $1/2 -\epsilon$ and rate $\Omega(\epsilon^2)$ (where an upper bound of $O(\epsilon^2\log(1/\epsilon))$ is known). Ta-Shma [STOC 2017] gave an explicit construction of $\epsilon$-balanced binary codes, where any two di...
2011.05500v1
2021-03-30
Equivalence between Sobolev spaces of first-order dominating mixed smoothness and unanchored ANOVA spaces on $\mathbb{R}^d$
We prove that a variant of the classical Sobolev space of first-order dominating mixed smoothness is equivalent (under a certain condition) to the unanchored ANOVA space on $\mathbb{R}^d$, for $d \geq 1$. Both spaces are Hilbert spaces involving weight functions, which determine the behaviour as different variables ten...
2103.16075v3
2021-06-13
Advantages of a semi-implicit scheme over a fully implicit scheme for Landau-Lifshitz-Gilbert equation
Magnetization dynamics in magnetic materials is modeled by the Landau-Lifshitz-Gilbert (LLG) equation. In the LLG equation, the length of magnetization is conserved and the system energy is dissipative. Implicit and semi-implicit schemes have been used in micromagnetics simulations due to their unconditional numerical ...
2106.06936v1
2021-08-06
A second-order semi-implicit method for the inertial Landau-Lifshitz-Gilbert equation
Recent theoretical and experimental advances show that the inertia of magnetization emerges at sub-picoseconds and contributes to the ultrafast magnetization dynamics which cannot be captured intrinsically by the LLG equation. Therefore, as a generalization, the inertial Landau-Lifshitz-Gilbert (iLLG) equation is propo...
2108.03060v1
2021-09-08
Flares, Rotation, and Planets of the AU Mic System from TESS Observations
AU Mic is a young ($\sim$24 Myr), pre-Main Sequence M~dwarf star that was observed in the first month of science observations of the Transiting Exoplanet Survey Satellite (TESS) and re-observed two years later. This target has photometric variability from a variety of sources that is readily apparent in the TESS light ...
2109.03924v1
2021-10-29
The TREX Survey: Kinematical Complexity Throughout M33's Stellar Disk and Evidence for a Stellar Halo
We present initial results from a large spectroscopic survey of stars throughout M33's stellar disk. We analyze a sample of 1667 red giant branch (RGB) stars extending to projected distances of $\sim 11$ kpc from M33's center ($\sim 18$ kpc, or $\sim 10$ scale lengths, in the plane of the disk). The line-of-sight veloc...
2110.15773v1
2021-11-23
Magnetism in Metastable and Annealed Compositionally Complex Alloys
Compositionally complex materials (CCMs) present a potential paradigm shift in the design of magnetic materials. These alloys exhibit long-range structural order coupled with limited or no chemical order. As a result, extreme local environments exist with a large opposing magnetic energy term, which can manifest large ...
2111.12188v1
2021-11-23
Controlling magnetic configuration in soft-hard bilayers probed by polarized neutron reflectometry
Hard/soft magnetic bilayer thin films have been widely used in data storage technologies and permanent magnet applications. The magnetic configuration and response to temperatures and magnetic fields in these heterostructures are considered to be highly dependent on the interfacial coupling. However, the intrinsic prop...
2111.12191v1
2022-01-18
On-demand electrical control of spin qubits
Once called a "classically non-describable two-valuedness" by Pauli , the electron spin is a natural resource for long-lived quantum information since it is mostly impervious to electric fluctuations and can be replicated in large arrays using silicon quantum dots, which offer high-fidelity control. Paradoxically, one ...
2201.06679v2
2022-04-28
Anti-microbial properties of a multi-component alloy
High traffic touch surfaces such as doorknobs, countertops, and handrails can be transmission points for the spread of pathogens, emphasizing the need to develop materials that actively self-sanitize. Metals are frequently used for these surfaces due to their durability, but many metals also possess antimicrobial prope...
2205.00886v1
2022-05-11
Models of Advance Recording Systems: A Multi-timescale Micromagnetic code for granular thin film magnetic recording systems
Micromagnetic modelling provides the ability to simulate large magnetic systems accurately without the computational cost limitation imposed by atomistic modelling. Through micromagnetic modelling it is possible to simulate systems consisting of thousands of grains over a time range of nanoseconds to years, depending u...
2205.05263v1
2022-10-11
Finite-time singularity formations for the Landau-Lifshitz-Gilbert equation in dimension two
We construct finite time blow-up solutions to the Landau-Lifshitz-Gilbert equation (LLG) from ${\mathbb R}^2$ into $S^2$ \begin{equation*} \begin{cases} u_t= a(\Delta u+|\nabla u|^2u) -b u\wedge \Delta u &\ \mbox{ in }\ {\mathbb R}^2\times(0,T), u(\cdot,0) = u_0\in S^2 &\ \mbox{ in }\ {\mathbb R}^2, \end{cases} \end{eq...
2210.05800v1
2023-01-03
Measuring Physical and Electrical Parameters in Free-Living Subjects: Motivating an Instrument to Characterize Analytes of Clinical Importance in Blood Samples
Significance: A path is described to increase the sensitivity and accuracy of body-worn devices used to monitor patient health. This path supports improved health management. A wavelength-choice algorithm developed at Mayo demonstrates that critical biochemical analytes can be assessed using accurate optical absorption...
2301.00938v2
2023-01-09
A Second Earth-Sized Planet in the Habitable Zone of the M Dwarf, TOI-700
We report the discovery of TOI-700 e, a 0.95 R$_\oplus$ planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA's Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inac...
2301.03617v1
2023-01-17
Introduction to Non-Invasive Current Estimation (NICE)
It is notoriously difficult to measure instantaneous supply current to a device such as an ASIC, FPGA, or CPU without also affecting the instantaneous supply voltage and compromising the operation of the device [21]. For decades designers have relied on rough estimates of dynamic load currents that stimulate a designed...
2301.10237v1
2023-02-08
Weighted Edit Distance Computation: Strings, Trees and Dyck
Given two strings of length $n$ over alphabet $\Sigma$, and an upper bound $k$ on their edit distance, the algorithm of Myers (Algorithmica'86) and Landau and Vishkin (JCSS'88) computes the unweighted string edit distance in $\mathcal{O}(n+k^2)$ time. Till date, it remains the fastest algorithm for exact edit distance ...
2302.04229v1
2023-03-07
Multilevel Monte Carlo methods for stochastic convection-diffusion eigenvalue problems
We develop new multilevel Monte Carlo (MLMC) methods to estimate the expectation of the smallest eigenvalue of a stochastic convection-diffusion operator with random coefficients. The MLMC method is based on a sequence of finite element (FE) discretizations of the eigenvalue problem on a hierarchy of increasingly finer...
2303.03673v2
2023-03-09
Zonostrophic instabilities in magnetohydrodynamic Kolmogorov flow
This paper concerns the stability of Kolmogorov flow u = (0, sin x) in the infinite (x,y)-plane. A mean magnetic field of strength B0 is introduced and the MHD linear stability problem studied for modes with wave-number k in the y-direction, and Bloch wavenumber l in the x-direction. The parameters governing the proble...
2303.05212v1
2023-03-30
Fate of entanglement in magnetism under Lindbladian or non-Markovian dynamics and conditions for their transition to Landau-Lifshitz-Gilbert classical dynamics
It is commonly assumed in spintronics and magnonics that localized spins within antiferromagnets are in the N\'{e}el ground state (GS), as well as that such state evolves, when pushed out of equilibrium by current or external fields, according to the Landau-Lifshitz-Gilbert (LLG) equation viewing localized spins as cla...
2303.17596v3
2024-02-07
Item-Level Heterogeneous Treatment Effects of Selective Serotonin Reuptake Inhibitors (SSRIs) on Depression: Implications for Inference, Generalizability, and Identification
In analysis of randomized controlled trials (RCTs) with patient-reported outcome measures (PROMs), Item Response Theory (IRT) models that allow for heterogeneity in the treatment effect at the item level merit consideration. These models for ``item-level heterogeneous treatment effects'' (IL-HTE) can provide more accur...
2402.04487v1
1995-02-16
Lyman alpha Emission from High-Redshift Galaxies
We summarise the results of a deep search for Lyman alpha emission from star-forming regions associated with damped Lyman alpha absorption systems and conclude that the Lyman alpha luminosity of high redshift galaxies is generally less than 10^(42) erg/s . We also present a newly discovered case, in the field of the QS...
9502076v1
1995-10-12
Limits on diffusive shock acceleration in dense and incompletely ionised media
The limits imposed on diffusive shock acceleration by upstream ion-neutral Alfven wave damping, and by ionisation and Coulomb losses of low energy particles, are calculated. Analytic solutions are given for the steady upstream wave excitation problem with ion-neutral damping and the resulting escaping upstream flux cal...
9510066v2
1995-11-28
Damping of GRR instability by direct URCA reactions
The role of direct URCA reactions in damping of the gravitational radiation driven instability is discussed. The temperature at which bulk viscosity suppresses completely this instability is calculated. The results are obtained analytically using recent calculations performed in the case of bulk viscosity due to the ...
9511136v1
1997-10-31
Abundances in Damped Lyman-alpha Systems and Chemical Evolution of High Redshift Galaxies
Recent abundance measurements in damped Lyman-alpha galaxies, supplemented with unpublished Keck observations, are discussed. The metallicity distribution with cosmic time is examined for clues about the degree of enrichment, the onset of initial star formation, and the nature of the galxies. The relative abundances of...
9710370v1
1998-05-08
Exploring the Damped Lyman-alpha Clouds with AXAF
The High Energy Transmission Grating (HETG) Spectrometer on the Advanced X-ray Astrophysics Facility (AXAF) (scheduled for launch in August, 1998) will provide a new tool for the study of absorption in the X-ray spectra of high redshift quasars due to the material along the line of sight. In this paper we try to explor...
9805110v1
1998-05-28
Photon Damping of Waves in Accretion Disks
MHD turbulence is generally believed to have two important functions in accretion disks: it transports angular momentum outward, and the energy in its shortest wavelength modes is dissipated into the heat that the disks radiate. In this paper we examine a pair of mechanisms which may play an important role in regulatin...
9805358v1
1998-06-11
Damping of differential rotation in neutron stars
We derive the transport relaxation times for quasiparticle-vortex scattering processes via nuclear force, relevant for the damping of differential rotation of superfluids in the quantum liquid core of a neutron star. The proton scattering off the neutron vortices provides the dominant resistive force on the vortex latt...
9806156v1
1999-03-10
Elemental abundances at early times: the nature of Damped Lyman-alpha systems
The distribution of element abundances with redshift in Damped Ly-alpha (DLA) systems can be adequately reproduced by the same model reproducing the halo and disk components of the Milky Way Galaxy at different galactocentric distances: DLA systems are well represented by normal spiral galaxies in their early evolution...
9903150v1
1999-07-26
Are Damped Ly-alpha Systems Large, Galactic Disks ?
The hypothesis that the Damped Ly-alpha systems (DLAs) are large, galactic disks (Milky Way sized) is tested by confronting predictions of models of the formation and evolution of (large) disk galaxies with observations, in particular the Zinc abundance distribution with neutral hydrogen column density found for DLAs. ...
9907349v1
1999-08-26
Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands
We have built a line list in the near-infrared J and H bands (1.00-1.34, 1.49-1.80 um) by gathering a series of laboratory and computed line lists. Oscillator strengths and damping constants were computed or obtained by fitting the solar spectrum. The line list presented in this paper is, to our knowledge, the most c...
9908296v1
1999-11-25
Probing Solar Convection
In the solar convection zone acoustic waves are scattered by turbulent sound speed fluctuations. In this paper the scattering of waves by convective cells is treated using Rytov's technique. Particular care is taken to include diffraction effects which are important especially for high-degree modes that are confined to...
9911469v1
1999-12-14
The Gas Reservoir for present day Galaxies : Damped Ly-alpha Absorption Systems
We present results from an ongoing search for galaxy counterparts of a subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers (DLAs). DLAs have several characteristics that make them essential in the process of understanding how galaxies formed in the early universe and evolved to the galaxies we s...
9912268v1
2000-06-22
Nuclear Reaction Rates in a Plasma: The Effect of Highly Damped Modes
The fluctuation-dissipation theorem is used to evaluate the screening factor of nuclear reactions due to the electromagnetic fluctuations in a plasma. We show that the commonly used Saltpeter factor is obtained if only fluctuations near the plasma eigenfrequency are assumed to be important (\omega \sim \omega_{pe}\ll T...
0006326v1
2000-09-06
The Cosmological Evolution of Quasar Damped Lyman-Alpha Systems
We present results from an efficient, non-traditional survey to discover damped Lyman-alpha (DLA) absorption-line systems with neutral hydrogen column densities N(HI)>2x10^{20} atoms cm^{-2} and redshifts z<1.65. Contrary to previous studies at higher redshift that showed a decrease in the cosmological mass density of ...
0009098v1
2001-01-13
Measuring Feedback in Damped Lyman Alpha Systems
We measure feedback (heating rates) in damped Lyman alpha systems from the cooling rate of the neutral gas. Since cooling occurs through [C II] 158 micron emission, we infer cooling from C II^{*} 1335.7 absorption lines detected with HIRES on the Keck I telescope. The inferred heating rates are about 30 times lower tha...
0101218v1
2001-04-18
The First Detection of Cobalt in a Damped Lyman Alpha System
We present the first ever detection of Cobalt in a Damped Lyman Alpha system (DLA) at z = 1.92. In addition to providing important clues to the star formation history of these high redshift galaxies, we discuss how studying the Co abundance in DLAs may also help to constrain models of stellar nucleosynthesis in a regim...
0104301v1
2001-05-09
Nuclear reaction rates and energy in stellar plasmas : The effect of highly damped modes
The effects of the highly damped modes in the energy and reaction rates in a plasma are discussed. These modes, with wavenumbers $k \gg k_{D}$, even being only weakly excited, with less than $k_{B}T$ per mode, make a significant contribution to the energy and screening in a plasma. When the de Broglie wavelength is muc...
0105153v1
2001-07-03
The HI Content and Extent of Low Surface Brightness Galaxies - Could LSB Galaxies be Responsible for Damped Ly-alpha Absorption?
Low surface brightness galaxies, those galaxies with a central surface brightness at least one magnitude fainter than the night sky, are often not included in discussions of extragalactic gas at z < 0.1. In this paper we review many of the properties of low surface brightness galaxies, including recent studies which in...
0107064v1
2001-09-10
H_2 molecules in damped systems
Damped Lyman alpha systems seen in the spectra of high-z QSOs arise in high-density neutral gas in which molecular hydrogen (H_2) should be conspicuous. Systematic searches to detect the H_2 lines redshifted into the Lyman alpha forest at <3400\AA are now possible thanks to the unique capabilities of UVES on the VLT. H...
0109155v1
2001-10-23
A scaling law of interstellar depletions as a tool for abundance studies of Damped Ly alpha systems
An analytical expression is presented that allows dust depletions to be estimated in different types of interstellar environments, including Damped Ly alpha systems. The expression is a scaling law of a reference depletion pattern and takes into account the possibility that the dust chemical composition may vary as a f...
0110499v1
2002-09-23
Outflows in Galaxies and Damped Ly-alpha System
Although quasar absorbers, and in particular Damped Lyman-alpha systems (DLAs) have proven a valuable tool to study the early Universe, their exact nature is so far poorly constrained. It has been suggested that outflows in galaxies might account for at least part of the DLA population. Observational evidences and mode...
0209463v1
2004-03-15
The Damping Wing of the Gunn-Peterson Absorption and Lyman-Alpha Emitters in the Pre-Reionization Era
We use a numerical simulation of cosmological reionization to estimate the likelihood of detecting Lyman-alpha emitting galaxies during the pre-reionization era. We show that it is possible to find galaxies even at z~9 that are barely affected by the dumping wing of the Gunn-Peterson absorption from the neutral IGM out...
0403345v1
2005-05-28
Cosmic ray transport in MHD turbulence
Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call for revisions in the picture of cosmic ray transport. In this paper we use recently obtained scaling laws for MHD modes to obtain the scattering frequency for cosmic rays. We account for the turbulence cutoff arising from both collisional and...
0505575v1
2005-06-09
Phantom damping of matter perturbations
Cosmological scaling solutions are particularly important in solving the coincidence problem of dark energy. We derive the equations of sub-Hubble linear matter perturbations for a general scalar-field Lagrangian--including quintessence, tachyon, dilatonic ghost condensate and k-essence--and solve them analytically for...
0506222v1
2005-06-22
A Damped Ly-alpha Absorption-line System in an Apparent Void at Redshift 2.38
We study the contents of an apparent void in the distribution of Ly-alpha emitting galaxies at redshift 2.38. We show that this void is not empty, but contains a damped Ly-alpha absorption-line system, seen in absorption against background QSO 2138-4427. Imaging does not reveal any galaxy associated with this absorptio...
0506525v1
2005-08-08
Fluorescence in damp air and comments on the radiative life time
Photon yields in damp air excited by an electron using a Sr90 $\beta$ source are compared withthose in dry air. Water vapors considerably reduce the yields, however, a further study is needed to evaluate the effects on the energy estimation of ultrahigh-energy cosmic rays. The relation of fluorescence efficiency to the...
0508183v1
2006-08-17
Electron thermal conductivity owing to collisions between degenerate electrons
We calculate the thermal conductivity of electrons produced by electron-electron Coulomb scattering in a strongly degenerate electron gas taking into account the Landau damping of transverse plasmons. The Landau damping strongly reduces this conductivity in the domain of ultrarelativistic electrons at temperatures belo...
0608371v1
2006-09-19
Dust, Metals and Diffuse Interstellar Bands in Damped Lyman Alpha Systems
Although damped Lyman alpha (DLA) systems are usually considered metal-poor, it has been suggested that this could be due to observational bias against metal-enriched absorbers. I review recent surveys to quantify the particular issue of dust obscuration bias and demonstrate that there is currently no compelling observ...
0609530v1
2006-11-08
Comments on Viscous Damping of Non-Adiabatic MHD Waves in an Unbounded Solar Coronal Plasma by Kumar and Kumar
Considering thermal conduction, compressive viscosity and optically thin radiation as damping mechanisms for MHD waves, we derive a six-order general dispersion relation. We point out a fundamental flaw in the derivation of five-order dispersion relation by Kumar and Kumar (2006) who adopt as a basis vector. The correc...
0611252v2
2007-01-10
Non-gaussianity in fluctuations from warm inflation
The scalar mode density perturbations in a the warm inflationary scenario are analysed with a view to predicting the amount of non-gaussianity produced by this scenario. The analysis assumes that the inflaton evolution is strongly damped by the radiation, with damping terms that are temperature independent. Entropy flu...
0701302v2
1998-05-22
WKB for a damped spin
The master equation for a damped spin well known from the theory of superradiance, is written as a finite-difference equation and solved by a WKB-like method. The propagator thus obtained looks like the van Vleck propagator of a certain classical Hamiltonian system with one degree of freedom. A new interpretation is pr...
9805018v1
1998-11-04
Cascades of energy and helicity in the GOY shell model of turbulence
The effect of extreme hyperviscous damping, $\nu k_n^p, p=\infty$ is studied numerically in the GOY shell model of turbulence. It has resently been demonstrated [Leveque and She, Phys. Rev. Lett, 75,2690 (1995)] that the inertial range scaling in the GOY model is non-universal and depending on the viscous damping. The ...
9811009v1
1994-02-04
Effects of Disorder in a Dilute Bose Gas
We discuss the effects of a weak random external potential on the properties of the dilute Bose gas at zero temperature. The results recently obtained by Huang and Meng for the depletion of the condensate and of the superfluid density are recovered. Results for the shift of the velocity of sound as well as for its damp...
9402015v1
1995-02-10
The influence of structure disorder on mean atomic momentum fluctuations and a spin-wave spectrum
The relation between atomic momenta fluctuations and density fluctuations is obtained in frames of mean-field approximation. Using two-time temperature Green functions within Tyablikov approximation the equations for spin excitation energy and damping are obtained. The asymptotics of energy and damping in the long-wave...
9502042v1
1997-02-13
Comment on "Collective Excitations of a Bose-Einstein Condensate in a Magnetic Trap"
We calculate the damping rate of collective excitations for a nearly pure Bose-Einstein condensate regarding the recent experiments in MIT [M.-O. Mews et al, Phys. Rev. Lett. 77, 988 (1996)]. The decay time of collective excitations obtained in our theoretical calculations agrees well with their experimental result. We...
9702122v1