49
49

Oct 28, 2014
10/14

by
Razi, Tahmine; Moslemzade, Seyed Hosein; Razi, Sedighe

texts

######
eye 49

######
favorite 0

######
comment 0

This article is from Journal of Dental Research, Dental Clinics, Dental Prospects , volume 3 . Abstract Background and aims: Panoramic radiography is a method widely used because of low absorbed dose in patients (ap-proximately 10 times less than that in the full mouth survey), reasonable cost and time. Disadvantages of this radiography technique are magnification and distortion as a result of unequal magnification, which can influence dimensional and angular measurements used in clinical...

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3517203

17
17

Oct 29, 2014
10/14

by
Smith, J; Baer, L; Blank, S; Dilawari, A; Carapetyan, K; Alvear, M; Utate, M; Curtin, J; Muggia, F

texts

######
eye 17

######
favorite 0

######
comment 0

This article is from ecancermedicalscience , volume 3 . Abstract Introduction: We describe a screening and prevention programme primarily targeting under-served minority women at high risk of breast and/or ovarian cancer. Women attending this Bellevue Hospital Center (BHC) Clinic were either self-referred from a variety of special outreach programmes or referred internally by medical professionals caring for relatives or friends. Our objective was to delineate referral sources and preliminary...

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3224011

49
49

Oct 25, 2014
10/14

by
Koodaryan, Roodabeh; Rafighi, Ali; Hafezeqoran, Ali

texts

######
eye 49

######
favorite 0

######
comment 0

This article is from Journal of Dental Research, Dental Clinics, Dental Prospects , volume 3 . Abstract Background and aims: Class III malocclusions are considered complex and difficult orthodontic problems to diagnose and treat. The purpose of this study was to investigate the morphologic characteristics of the craniofacial complex of adults with Class III malocclusion in an Iranian population. Materials and methods: Lateral cephalometric radiographs of 50 patients with Class III malocclusion...

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3517198

39
39

Oct 24, 2014
10/14

by
Minaev, Boris; Lindgren, Mikael

texts

######
eye 39

######
favorite 0

######
comment 0

This article is from Sensors (Basel, Switzerland) , volume 9 . Abstract Bis-MPA dendron-coated free-base tetraphenylporphyrin and zinc-tetraphenyl-porphyrin (TPPH2 and TPPZn) were studied in comparison with simple porphyrins (H2P, ZnP) by theoretical simulation of their infrared, Raman and electronic absorption spectra, as well as fluorescense emission. Infrared and fluorescence spectra of the dendrimers were measured and interpreted along with time-resolved measurements of the fluorescence....

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3345821

24
24

Sep 23, 2013
09/13

by
Carlos Hernandez-Monteagudo; Shirley Ho

texts

######
eye 24

######
favorite 0

######
comment 0

The peculiar motion of ionized baryons is known to introduce temperature anisotropies in the CMB by means of the kinetic Sunyaev-Zel'dovich effect (kSZ). In this work, we present an all sky computation of angular power spectrum of the temperature anisotropies introduced by kSZ momentum of all baryons in the Universe during and after reionization. In an attempt to study the bulk flows of the missing baryons not yet detected, we address separately the contribution from all baryons in the IGM and...

Source: http://arxiv.org/abs/0903.2814v1

26
26

Sep 23, 2013
09/13

by
Lisa Winter; Richard Mushotzky; Yuichi Terashima; Yoshihiro Ueda

texts

######
eye 26

######
favorite 0

######
comment 0

The fraction of Compton thick sources is one of the main uncertainties left in understanding the AGN population. The Swift Burst Alert Telescope (BAT) all-sky survey, for the first time gives us an unbiased sample of AGN for all but the most heavily absorbed sources (log NH > 25). Still, the BAT spectra (14 - 195 keV) are time-averaged over months of observations and therefore hard to compare with softer spectra from the Swift XRT or other missions. This makes it difficult to distinguish...

Source: http://arxiv.org/abs/0903.2802v1

50
50

Sep 21, 2013
09/13

by
Stephan Durr

texts

######
eye 50

######
favorite 0

######
comment 0

A Lie-algebra based recipe for smoothing gauge links in lattice field theory is presented, building on the matrix logarithm. With or without hypercubic nesting, this LOG/HYL smearing yields fat links which are differentiable w.r.t. the original ones. This is essential for defining UV-filtered ("fat link") fermion actions which may be simulated with a HMC-type algorithm. The effect of this smearing on the distribution of plaquettes and on the residual mass of tree-level O(a)-improved...

Source: http://arxiv.org/abs/0709.4110v2

27
27

Sep 23, 2013
09/13

by
Garry W. Angus; Antonaldo Diaferio

texts

######
eye 27

######
favorite 0

######
comment 0

We re-investigate the old problem of the survival of the five globular clusters orbiting the Fornax dwarf galaxy in both standard and modified Newtonian dynamics. For the first time in the history of the topic, we use accurate mass models for the Fornax dwarf, obtained through Jeans modelling of the recently published line of sight velocity dispersion data, and we are also not resigned to circular orbits for the globular clusters. Previously conceived problems stem from fixing the starting...

Source: http://arxiv.org/abs/0903.2874v1

32
32

Sep 23, 2013
09/13

by
N. N. Nikolaev; V. R. Zoller

texts

######
eye 32

######
favorite 0

######
comment 0

One of the well known effects of the asymptotic freedom is splitting of the leading-$\log$ BFKL pomeron into a series of isolated poles in complex angular momentum plane. Following our earlier works we explore the phenomenological consequences of the emerging BFKL-Regge factorized expansion for the small-$x$ charm ($F_2^c$) and beauty ($F_{2}^{b}$) structure functions of the proton. As we found earlier,the color dipole approach to the BFKL dynamics predicts uniquely decoupling of subleading...

Source: http://arxiv.org/abs/0903.2729v1

69
69

Sep 21, 2013
09/13

by
Nikolay Gromov; Vladimir Kazakov; Pedro Vieira

texts

######
eye 69

######
favorite 0

######
comment 0

We present a set of functional equations defining the anomalous dimensions of arbitrary local single trace operators in planar N=4 SYM theory. It takes the form of a Y-system based on the integrability of the dual superstring sigma-model on the AdS_5xS^5 background. This Y-system passes some very important tests: it incorporates the full asymptotic Bethe ansatz at large length of operator L, including the dressing factor, and it confirms all recently found wrapping corrections. The recently...

Source: http://arxiv.org/abs/0901.3753v3

36
36

Sep 23, 2013
09/13

by
Jose A. Diaz-Garcia; R. Gutierrez-Jaimez

texts

######
eye 36

######
favorite 0

######
comment 0

Several matrix variate hypergeometric type distributions are derived. The compound distributions of left-spherical matrix variate elliptical distributions and inverted hypergeometric type distributions with matrix arguments are then proposed. The scale mixture of left-spherical matrix variate elliptical distributions and univariate inverted hypergeometric type distributions is also derived as a particular case of the compound distribution approach.

Source: http://arxiv.org/abs/0903.2875v1

25
25

Sep 23, 2013
09/13

by
Frans Snik; Radek Melich; Christoph Keller

texts

######
eye 25

######
favorite 0

######
comment 0

We present the design and the prototype of the Small Synoptic Second Solar Spectrum Telescope (S5T), which can autonomously measure scattering polarization signals on a daily basis with large sensitivity and accuracy. Its data will be used to investigate the nature of weak, turbulent magnetic fields through the Hanle effect in many lines. Also the relation between those fields and the global solar dynamo can be revealed by spanning the observations over a significant fraction of a solar cycle....

Source: http://arxiv.org/abs/0903.2730v1

38
38

Sep 23, 2013
09/13

by
Susmit Jha; Sanjit A. Seshia; Rhishikesh Limaye

texts

######
eye 38

######
favorite 0

######
comment 0

Satisfiability solvers are increasingly playing a key role in software verification, with particularly effective use in the analysis of security vulnerabilities. String processing is a key part of many software applications, such as browsers and web servers. These applications are susceptible to attacks through malicious data received over network. Automated tools for analyzing the security of such applications, thus need to reason about strings. For efficiency reasons, it is desirable to have...

Source: http://arxiv.org/abs/0903.2825v1

41
41

Sep 19, 2013
09/13

by
Andy T. S. Wan; M. H. S. Amin; Shannon X. Wang

texts

######
eye 41

######
favorite 0

######
comment 0

We study the effect of an environment consisting of noninteracting two level systems on Landau-Zener transitions with an interest on the performance of an adiabatic quantum computer. We show that if the environment is initially at zero temperature, it does not affect the transition probability. An excited environment, however, will always increase the probability of making a transition out of the ground state. For the case of equal intermediate gaps, we find an analytical upper bound for the...

Source: http://arxiv.org/abs/cond-mat/0703085v3

39
39

Sep 23, 2013
09/13

by
Catalin D. Spataru; Mark S. Hybertsen; Steven G. Louie; Andrew J. Millis

texts

######
eye 39

######
favorite 0

######
comment 0

The Anderson model for a single impurity coupled to two leads is studied using the $GW$ approximation in the strong electron-electron interaction regime as a function of the alignment of the impurity level relative to the chemical potentials in the leads. We employ a non-equilibrium Green's function technique to calculate the electron self-energy, the spin density and the current as a function of bias across the junction. In addition we develop an expression for the change in the expectation...

Source: http://arxiv.org/abs/0903.2683v1

31
31

Sep 23, 2013
09/13

by
L. H. Ford; N. F. Svaiter

texts

######
eye 31

######
favorite 0

######
comment 0

Quantum fluctuations in the density of a fluid with a linear phonon dispersion relation are studied. In particular, we treat the changes in these fluctuations due to non-classical states of phonons and to the presence of boundaries. These effects are analogous to similar effects in relativistic quantum field theory, and we argue that the case of the fluid is a useful analog model for effects in field theory. We further argue that the changes in the mean squared density are in principle...

Source: http://arxiv.org/abs/0903.2694v1

27
27

Sep 23, 2013
09/13

by
Brendon W. Lovett; Ahsan Nazir

texts

######
eye 27

######
favorite 0

######
comment 0

Coherence is a familiar concept in physics: It is the driving force behind wavelike phenomena such as the diffraction of light. Moreover, wave-particle duality implies that all quantum objects can exhibit coherence, and this quantum coherence is crucial to understanding the behaviour of a plethora of systems. In this article, which is written at an undergraduate level, we shall briefly introduce what is meant by coherence in a well-known classical setting, before going on to describe its...

Source: http://arxiv.org/abs/0903.2746v1

24
24

Sep 23, 2013
09/13

by
S. T. Belinschi; D. Shlyakhtenko

texts

######
eye 24

######
favorite 0

######
comment 0

In this paper we give an analytic interpretation of free convolution of type B, introduced by Biane, Goodman and Nica, and provide a new formula for its computation. This formula allows us to show that free additive convolution of type B is essentially a re-casting of conditionally free convolution. We put in evidence several aspects of this operation, the most significant being its apparition as an 'intertwiner' between derivation and free convolution of type A. We also show connections...

Source: http://arxiv.org/abs/0903.2721v1

31
31

Sep 20, 2013
09/13

by
Peter K. F. Kuhfittig

texts

######
eye 31

######
favorite 0

######
comment 0

The purpose of this paper is to examine the possible existence or construction of traversable wormholes supported by generalized Chaplygin gas (GCG) by starting with a general line element and the Einstein tensor, together with the equation of state, thereby continuing an earlier study by the author of wormholes supported by phantom energy. Numerical techniques are used to demonstrate the existence of wormhole spacetimes that (1) meet the flare-out conditions at the throat, (2) are traversable...

Source: http://arxiv.org/abs/0802.3656v3

25
25

Sep 23, 2013
09/13

by
Pierre Andreoletti

texts

######
eye 25

######
favorite 0

######
comment 0

We study a random walk in a random environment (RWRE) on $\Z^d$, $1 \leq d < +\infty$. The main assumptions are that conditionned on the environment the random walk is reversible. Moreover we construct our environment in such a way that the walk can't be trapped on a single point like in some particular RWRE but in some specific d-1 surfaces. These surfaces are basic surfaces with deterministic geometry. We prove that the local time in the neighborhood of these surfaces is driven by a...

Source: http://arxiv.org/abs/0903.2696v1

39
39

Sep 23, 2013
09/13

by
J. -F. Desmurs; C. Codella; J. Santiago-Garcia; M. Tafalla; R. Bachiller

texts

######
eye 39

######
favorite 0

######
comment 0

We have performed observations of water maser emission towards a sample of low-mass protostars, in order to investigate the properties of jets associated with the earliest stages of star formation and their interaction with the surrounding medium. The main aim is to measure the absolute positions and proper motions of the H_2O spots in order to investigate the kinematics of the region from where the jet is launched. We imaged the protostars in the nearby region NGC 1333-IRAS 4 in the water...

Source: http://arxiv.org/abs/0903.2770v1

23
23

Sep 23, 2013
09/13

by
S. Baunack; K. Aulenbacher; D. Balaguer Ríos; L. Capozza; J. Diefenbach; B. Gläser; D. v. Harrach; Y. Imai; E. M. Kabuß; R. Kothe; J. H. Lee; H. Merkel; M. C. Mora Espí; U. Müller; E. Schilling; G. Stephan; C. Weinrich; J. Arvieux; M. A. El-Yakoubi; R. Kunne; F. E. Maas; M. Morlet; S. Ong; J. van de Wiele; S. Kowalski; Y. Prok; S. Taylor

texts

######
eye 23

######
favorite 0

######
comment 0

A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q^2=0.22 (GeV/c)^2 is reported here. The measured asymmetry is A_LR=(-17.23 +- 0.82_stat +-0.89_syst) ppm. The Standard Model prediction assuming no strangeness is A_0=(-15.87 +- 1.22) ppm. In combination with previous results from measurements at forward angles, it it possible to disentangle for the first time the strange electric and magnetic...

Source: http://arxiv.org/abs/0903.2733v1

40
40

Sep 23, 2013
09/13

by
Daniel Allcock

texts

######
eye 40

######
favorite 0

######
comment 0

We prove the following: there are infinitely many finite-covolume (resp. cocompact) Coxeter groups acting on hyperbolic space H^n for every n < 20 (resp. n < 7). When n=7 or 8, they may be taken to be nonarithmetic. Furthermore, for 1 < n < 20, with the possible exceptions n=16 and 17, the number of essentially distinct Coxeter groups in H^n with noncompact fundamental domain of volume less than or equal to V grows at least exponentially with respect to V. The same result holds for...

Source: http://arxiv.org/abs/0903.0138v2

33
33

Sep 22, 2013
09/13

by
Armin Lühr; Alejandro Saenz

texts

######
eye 33

######
favorite 0

######
comment 0

The stopping power of antiprotons in atomic and molecular hydrogen as well as helium was calculated in an impact-energy range from 1 keV to 6.4 MeV. In the case of H2 and He the targets were described with a single-active electron model centered on the target. The collision process was treated with the close-coupling formulation of the impact-parameter method. An extensive comparison of the present results with theoretical and experimental literature data was performed in order to evaluate...

Source: http://arxiv.org/abs/0812.5058v2

30
30

Sep 23, 2013
09/13

by
Frédéric Faure

texts

######
eye 30

######
favorite 0

######
comment 0

We consider a simple model of partially expanding map on the torus. We study the spectrum of the Ruelle transfer operator and show that in the limit of high frequencies in the neutral direction (this is a semiclassical limit), the spectrum develops a spectral gap, for a generic map. This result has already been obtained by M. Tsujii (05). The novelty here is that we use semiclassical analysis which provides a different and quite natural description. We show that the transfer operator is a...

Source: http://arxiv.org/abs/0903.2747v1

63
63

Sep 23, 2013
09/13

by
Valerie J. Mikles; Peggy Varniere; Stephen S. Eikenberry; Jerome Rodriguez; Dave Rothstein

texts

######
eye 63

######
favorite 0

######
comment 0

It is widely believed that the low frequency quasi-periodic X-ray oscillations observed in microquasars are correlated to, but do not originate at, the physical radius of the inner edge of the accretion disk. Models relating the QPO frequency and color radius are hindered by observations showing contradicting trend correlations between the microquasars GRO 1655-40, XTE J1550-564 and GRS 1915+105. The first shows a negative correlation and the latter two a positive one. By taking into account...

Source: http://arxiv.org/abs/0903.2680v1

105
105

Sep 23, 2013
09/13

by
Xavier Caicedo; Ricardo Oscar Rodriguez

texts

######
eye 105

######
favorite 0

######
comment 0

In this paper we consider an approach where both propositions and the accessibility relation are infinitely many-valued over G\"{o}del algebras. In particular, we consider separately the $\Box $-fragment and the $\Diamond $-fragment of our G\"{o}del modal logic and prove that both logics are complete with respect to the class of models with values in the linear Hetying algebra [0,1]. In addition, we show that the first fragment is uniquely determined by the class of models having...

Source: http://arxiv.org/abs/0903.2767v1

94
94

Sep 23, 2013
09/13

by
S. Regnier

texts

######
eye 94

######
favorite 0

######
comment 0

The origin and evolution of the magnetic helicity in the solar corona are not well understood. For instance, the magnetic helicity of an active region is often about $10^{42}$ Mx$^2$ ($10^{26}$ Wb$^{2}$), but the observed processes whereby it is thought to be injected into the corona do not yet provide an accurate estimate of the resulting magnetic helicity budget or time evolution. The variation in magnetic helicity is important for understanding the physics of flares, coronal mass ejections,...

Source: http://arxiv.org/abs/0903.2697v1

82
82

Sep 17, 2013
09/13

by
Tobias Salger; Gunnar Ritt; Carsten Geckeler; Sebastian Kling; Martin Weitz

texts

######
eye 82

######
favorite 0

######
comment 0

We report on experiments studying transport properties of an atomic Bose-Einstein condensate in an optical lattice of spatial period $\lambda/2n$, where $n$ is an integer, realized with the dispersion of multiphoton Raman transitions. We observe Bloch oscillations, as a clear effect of quantum transport, in the sub-wavelength scale periodicity lattice. The unusually strong localisation of atoms is evident from the measured effective mass. Future prospects of the novel lattice structures are...

Source: http://arxiv.org/abs/0711.1772v3

36
36

Sep 23, 2013
09/13

by
Wei-Hong Gao

texts

######
eye 36

######
favorite 0

######
comment 0

Strong optical and near-infrared (NIR) flares were discovered in the afterglow of GRB 080129. Their temporal behaviors, the sudden emergence and the quick disappearance, are rather similar to that of many X-ray flares (for instance, the giant flare of GRB 050502B). We argue that the optical/NIR flares following GRB 080129 are a low energy analogy of the X-ray flares and the most likely interpretation is the "late internal shock model". In this model, both the very sharp decline and...

Source: http://arxiv.org/abs/0903.2768v1

126
126

Sep 23, 2013
09/13

by
A. Iucci; M. A. Cazalilla

texts

######
eye 126

######
favorite 0

######
comment 0

The dynamics of the Luttinger model and the sine-Gordon model (at the Luther-Emery point and in the semiclassical approximation) after a quantum quench is studied. We compute in detail one and two-point correlation functions for different types of quenches: from a non-interacting to an interacting Luttinger model and vice-versa, and from the gapped to the gapless phase of the sine-Gordon model and vice-versa. A progressive destruction of the Fermi gas features in the momentum distribution is...

Source: http://arxiv.org/abs/0903.1205v2

41
41

Sep 18, 2013
09/13

by
Yonina C. Eldar

texts

######
eye 41

######
favorite 0

######
comment 0

A traditional assumption underlying most data converters is that the signal should be sampled at a rate exceeding twice the highest frequency. This statement is based on a worst-case scenario in which the signal occupies the entire available bandwidth. In practice, many signals are sparse so that only part of the bandwidth is used. In this paper, we develop methods for low-rate sampling of continuous-time sparse signals in shift-invariant (SI) spaces, generated by m kernels with period T. We...

Source: http://arxiv.org/abs/0806.3332v2

47
47

Sep 23, 2013
09/13

by
Charles P. Meaney; Tim Duty; Ross H. McKenzie; Gerard J. Milburn

texts

######
eye 47

######
favorite 0

######
comment 0

We consider the steady states of a harmonic oscillator coupled so strongly to a two-level system (a qubit) that the rotating wave approximation cannot be made. The Hamiltonian version of this model is known as the $E\otimes\beta$ Jahn-Teller model. The semiclassical version of this system exhibits a fixed point bifurcation, which in the quantum model leads to a ground state with substantial entanglement between the oscillator and the qubit. We show that the dynamical bifurcation survives in a...

Source: http://arxiv.org/abs/0903.2681v1

35
35

Sep 23, 2013
09/13

by
D. Speer; R. Eichhorn; P. Reimann

texts

######
eye 35

######
favorite 0

######
comment 0

We consider an overdamped Brownian particle, exposed to a two-dimensional, square lattice potential and a rectangular ac-drive. Depending on the driving amplitude, the linear response to a weak dc-force along a lattice symmetry axis consist in a mobility in basically any direction. In particular, motion exactly opposite to the applied dc-force may arise. Upon changing the angle of the dc-force relatively to the square lattice, the particle motion remains predominantly opposite to the dc-force....

Source: http://arxiv.org/abs/0903.2736v1

95
95

Sep 23, 2013
09/13

by
Enrique Munoz; Jeong-Man Park; Michael W. Deem

texts

######
eye 95

######
favorite 0

######
comment 0

To represent the evolution of nucleic acid and protein sequence, we express the parallel and Eigen models for molecular evolution in terms of a functional integral representation with an $h$-letter alphabet, lifting the two-state, purine/pyrimidine assumption often made in quasi-species theory. For arbitrary $h$ and a general mutation scheme, we obtain the solution of this model in terms of a maximum principle. Euler's theorem for homogeneous functions is used to derive this `thermodynamic'...

Source: http://arxiv.org/abs/0903.2004v2

32
32

Sep 23, 2013
09/13

by
D. B. Melrose; M. Z. Rafat; Q. Luo

texts

######
eye 32

######
favorite 0

######
comment 0

We consider the motion of a charge in a large amplitude electrostatic wave with a triangular wave form relevant to an oscillating model of a pulsar magnetosphere. The (one-dimensional) orbit of a particle in such a wave is found exactly in terms of Weierstrass functions. The result is used to discuss linear acceleration emission (at both low and high frequencies) in an oscillating model for pulsars. An explicit expression for the emissivity is derived in an accompanying paper (Melrose & Luo...

Source: http://arxiv.org/abs/0903.2877v1

32
32

Sep 23, 2013
09/13

by
Jong-Geon Bu; Jae Hyung Yee; Hyeong-Chan Kim

texts

######
eye 32

######
favorite 0

######
comment 0

The differential structure on the kappa-Minkowski spacetime from Jordanian twist of Weyl algebra is constructed, and it is shown to be closed in 4-dimensions in contrast to the conventional formulation. Based on this differential structure, we have formulated a scalar field theory in this kappa-Minkowski spacetime.

Source: http://arxiv.org/abs/0903.0040v2

36
36

Sep 23, 2013
09/13

by
Marina Ghisi; Massimo Gobbino

texts

######
eye 36

######
favorite 0

######
comment 0

We consider the hyperbolic-parabolic singular perturbation problem for a degenerate quasilinear Kirchhoff equation with weak dissipation. This means that the coefficient of the dissipative term tends to zero when t tends to +infinity. We prove that the hyperbolic problem has a unique global solution for suitable values of the parameters. We also prove that the solution decays to zero, as t tends to +infinity, with the same rate of the solution of the limit problem of parabolic type.

Source: http://arxiv.org/abs/0903.2713v1

48
48

Sep 22, 2013
09/13

by
Krzysztof G. Hełminiak

texts

######
eye 48

######
favorite 0

######
comment 0

We study the impact of the atmospheric differential chromatic refraction on the measurements and precision of relative astrometry. Specifically, we address the problem of measuring the separations of close pairs of binary stars with adaptive optics in the J and K bands. We investigate the influence of weather conditions, zenithal distance, star's spectral type and observing wavelength on the astrometric precision and determine the accuracy of these parameters that is necessary to detect...

Source: http://arxiv.org/abs/0805.3369v3

35
35

Sep 23, 2013
09/13

by
Bogdan Mihaila; Andres Cardenas

texts

######
eye 35

######
favorite 0

######
comment 0

We study the ground-state properties of a dilute gas of strongly-interacting fermions in the framework of the coupled-cluster expansion (CCE). We demonstrate that properties such as universality, opening of a gap in the excitation spectrum and applicability of s-wave approximations appear naturally in the CCE approach. In the zero-density limit, we show that the ground-state energy density depends on only one parameter which in turn may depend at most on the spatial dimensionality of the system.

Source: http://arxiv.org/abs/0903.2786v1

32
32

Sep 23, 2013
09/13

by
J. J. Tobin; L. Hartmann; G. Furesz; M. Mateo; S. T. Megeath

texts

######
eye 32

######
favorite 0

######
comment 0

We present a kinematic study of the Orion Nebula Cluster based upon radial velocities measured by multi-fiber echelle spectroscopy at the 6.5 meter MMT and Magellan telescopes. Velocities are reported for 1613 stars, with multi-epoch data for 727 objects as part of our continuing effort to detect and analyze spectroscopic binaries. We confirm and extend the results of Furesz et al. showing that the ONC is not relaxed, consistent with its youth, and that the stars generally follow the...

Source: http://arxiv.org/abs/0903.2775v1

65
65

Sep 23, 2013
09/13

by
W. Münzer; A. Neubauer; S. Mühlbauer; C. Franz; T. Adams; F. Jonietz; R. Georgii; P. Böni; B. Pedersen; M. Schmidt; A. Rosch; C. Pfleiderer

texts

######
eye 65

######
favorite 0

######
comment 0

We report a comprehensive small angle neutron scattering study (SANS) of the magnetic phase diagram of the doped semiconductor Fe_{1-x}Co_{x}Si for x=0.2 and 0.25. For magnetic field parallel to the neutron beam we observe a six-fold intensity pattern under field-cooling, which identifies the A-phase of Fe_{1-x}Co_{x}Si as a skyrmion lattice. The regime of the skyrmion lattice is highly hysteretic and extents over a wide temperature range, consistent with the site disorder of the Fe and Co...

Source: http://arxiv.org/abs/0903.2587v1

36
36

Sep 23, 2013
09/13

by
Andrew V. Knyazev; Klaus Neymeyr

texts

######
eye 36

######
favorite 0

######
comment 0

Preconditioned eigenvalue solvers (eigensolvers) are gaining popularity, but their convergence theory remains sparse and complex. We consider the simplest preconditioned eigensolver--the gradient iterative method with a fixed step size--for symmetric generalized eigenvalue problems, where we use the gradient of the Rayleigh quotient as an optimization direction. A sharp convergence rate bound for this method has been obtained in 2001--2003. It still remains the only known such bound for any of...

Source: http://arxiv.org/abs/0801.3099v3

42
42

Sep 23, 2013
09/13

by
Ghaya Baili; Mehdi Alouini; Thierry Malherbe; Daniel Dolfi; Isabelle Sagnes; Fabien Bretenaker

texts

######
eye 42

######
favorite 0

######
comment 0

The transition between the class-B and class-A dynamical behaviors of a semiconductor laser is directly observed by continuously controlling the lifetime of the photons in a cavity of sub-millimetric to centimetric length. It is experimentally and theoretically proved that the transition from a resonant to an overdamped behavior occurs progressively, without any discontinuity. In particular, the intermediate regime is found to exhibit features typical from both the class-A and class-B regimes....

Source: http://arxiv.org/abs/0903.2827v1

34
34

Sep 23, 2013
09/13

by
G. W. Gibbons; H. Lu; C. N. Pope

texts

######
eye 34

######
favorite 0

######
comment 0

It is well known that every compact simple group manifold G admits a bi-invariant Einstein metric, invariant under G_L\times G_R. Less well known is that every compact simple group manifold except SO(3) and SU(2) admits at least one more homogeneous Einstein metric, invariant still under G_L but with some, or all, of the right-acting symmetry broken. (SO(3) and SU(2) are exceptional in admitting only the one, bi-invariant, Einstein metric.) In this paper, we look for Einstein metrics on three...

Source: http://arxiv.org/abs/0903.2493v1

36
36

Sep 22, 2013
09/13

by
Ernesto Nungesser; Alan D. Rendall

texts

######
eye 36

######
favorite 0

######
comment 0

A proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the deep results of Ringstr\"om on strong cosmic...

Source: http://arxiv.org/abs/0901.4000v2

34
34

Sep 22, 2013
09/13

by
Ioan Baldea; Horst Koppel

texts

######
eye 34

######
favorite 0

######
comment 0

We present theoretical results demonstrating that photoionization can be a useful tool for investigating single--electron transistors. Suggestions are given on how to conduct experiments using photoionization alone or in combination with transport measurements.

Source: http://arxiv.org/abs/0811.2757v2

33
33

Sep 23, 2013
09/13

by
Victor Beresnevich; Sanju Velani; Robert C. Vaughan

texts

######
eye 33

######
favorite 0

######
comment 0

The inhomogeneous metric theory for the set of simultaneously $\psi$-approximable points lying on a planar curve is developed. Our results naturally incorporate the homogeneous Khintchine-Jarnik type theorems recently established in [Ann. of Math. (2), 166 (2007), pp. 367-426] and [Invent. Math., 166 (2006), pp. 103-124]. The key lies in obtaining essentially the best possible results regarding the distribution of `shifted' rational points near planar curves.

Source: http://arxiv.org/abs/0903.2817v1

34
34

Sep 18, 2013
09/13

by
R. Lipperheide; U. Wille

texts

######
eye 34

######
favorite 0

######
comment 0

Spin-polarized electron transport in diluted magnetic semiconductors (DMS) in the paramagnetic phase is described within the thermoballistic transport model. In this (semiclassical) model, the ballistic and diffusive transport mechanisms are unified in terms of a thermoballistic current in which electrons move ballistically across intervals enclosed between arbitrarily distributed points of local thermal equilibrium. The contribution of each interval to the current is governed by the momentum...

Source: http://arxiv.org/abs/0809.4353v2

35
35

Sep 23, 2013
09/13

by
Michel J. P. Gingras

texts

######
eye 35

######
favorite 0

######
comment 0

Geometric frustration usually arises in systems that comprise magnetic moments (spins) which reside on the sites of a lattice made up of elementary triangular or tetrahedral units and which interact via antiferromagnetic nearest-neighbor exchange. Albeit much less common, geometric frustration can also arise in systems with strong non-collinear single-ion easy-axis (Ising-like) anisotropy and ferromagnetically} coupled spins. This is what happens in some pyrochlore oxide materials where...

Source: http://arxiv.org/abs/0903.2772v1