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Deformation and fracture of echinoderm collagen networks
https://cds.cern.ch/record/2217825
Collagen networks provide the main structural component of most tissues and represent an important ingredient for bio-mimetic materials for bio-medical applications. Here we study the mechanical properties of stiff collagen networks derived from three different echinoderms and show that they exhibit non-linear stiffening followed by brittle fracture. The disordered nature of the network leads to strong sample-to-sample fluctuations in elasticity and fracture strength. We perform numerical simulations of a three dimensional model for the deformation of a cross-linked elastic fibril network which is able to reproduce the macroscopic features of the experimental results and provide insights into the internal mechanics of stiff collagen networks. Our numerical model provides an avenue for the design of collagen membranes with tunable mechanical properties.Ovaska, MarkusBertalan, ZsoltMiksic, AmandineSugni, MichelaDi Benedetto, CristianoFerrario, CinziaLeggio, LivioGuidetti, LucaAlava, Mikko JLa Porta, Caterina A MZapperi, StefanoFri, 23 Sep 2016 07:10:51 GMT22 Sep 2016arXiv:1609.06847https://cds.cern.ch/record/2217825['arXiv:1609.06847']arXiv:1609.06847Fluctuations in protein aggregation: Design of preclinical screening for early diagnosis of neurodegenerative disease
https://cds.cern.ch/record/2217824
Autocatalytic fibril nucleation has recently been proposed to be a determining factor for the spread of neurodegenerative diseases, but the same process could also be exploited to amplify minute quantities of protein aggregates in a diagnostic context. Recent advances in microfluidic technology allow analysis of protein aggregation in micron-scale samples potentially enabling such diagnostic approaches, but the theoretical foundations for the analysis and interpretation of such data are so far lacking. Here we study computationally the onset of protein aggregation in small volumes and show that the process is ruled by intrinsic fluctuations whose volume dependent distribution we also estimate theoretically. Based on these results, we develop a strategy to quantify in silico the statistical errors associated with the detection of aggregate containing samples. Our work opens a new perspective on the forecasting of protein aggregation in asymptomatic subjects.Costantini, GiulioBudrikis, ZoeTaloni, AlessandroBuell, Alexander KZapperi, StefanoLa Porta, Caterina A MFri, 23 Sep 2016 07:10:50 GMT22 Sep 2016arXiv:1609.06843https://cds.cern.ch/record/2217824['arXiv:1609.06843']arXiv:1609.06843Carbon cluster diagnostics-I: Direct Recoil Spectroscopy (DRS) of Ar+ and Kr+ bombarded graphite
https://cds.cern.ch/record/2217817
Measurements of the energy spectra of multiply charged positive and negative carbon ions recoiling from graphite surface under 100 and 150 keV argon and krypton ion bombardment are presented. With the energy spectrometer set at recoil angle of 79.5 degrees, direct recoil (DR) peaks have been observed with singly as well as multiply charged carbon ions , where n = 1 to 6. These monatomic and cluster ions have been observed recoiling with the characteristic recoil energy E(DR) . We have observed sharp DR peaks. A collimated projectile beam with small divergence is supplemented with a similar collimation before the energy analyzer to reduce the background of sputtered ions due to scattered projectiles.Ahmad, ShoaibAkhtar, M NQayyum, AAhmad, BBahar, KArshed, WFri, 23 Sep 2016 07:10:49 GMT20 Sep 2016arXiv:1609.06746https://cds.cern.ch/record/2217817['arXiv:1609.06746']arXiv:1609.06746Two New Theories for the Current Charge Relativity and the Electric Origin of the Magnetic Force Between Two Filamentary Current Elements
https://cds.cern.ch/record/2217816
This paper presents two new theories and a new current representation to explain the magnetic force between two filamentary current elements as a result of electric force interactions between current charges. The first theory states that a current has an electric charge relative to its moving observer. The second theory states that the magnetic force is an electric force in origin. The new current representation characterizes a current as equal amounts of positive and negative point charges moving in opposite directions at the speed of light. Previous work regarded electricity and magnetism as different aspects of the same subject. One effort was made by Johnson to unify the origin of electricity and magnetism, but this effort yielded a formula that is unequal to the well-known magnetic force law. The explanation provided for the magnetic force depends on three factors: 1) representing the electric current as charges moving at the speed of light, 2) considering the relative velocity between moving charges, and 3) analyzing the electric field spreading in the space due to the movement of charges inside current elements. The electric origin of the magnetic force is proved by deriving the magnetic force law and Biot-Savart law using the electric force law. This paper is helpful for unifying the concepts of magnetism and electricity.Shadid, Waseem G TFri, 23 Sep 2016 07:10:49 GMT21 Sep 2016arXiv:1609.06731https://cds.cern.ch/record/2217816['arXiv:1609.06731']arXiv:1609.06731Proof of Bekenstein-Mukhanov ansatz in loop quantum gravity
https://cds.cern.ch/record/2217765
A simple proof of Bekenstein-Mukhanov(BM) ansatz is given within the loop quantum gravity(LQG) framework. The macroscopic area of an equilibrium black hole horizon indeed manifests a linear quantization. The quantum number responsible for this discreteness of the macroscopic area has a physical meaning in the LQG framework, unlike the ad hoc one that remained unexplained in BM ansatz.Majhi, AbhishekFri, 23 Sep 2016 07:08:08 GMT22 Sep 2016arXiv:1609.07125https://cds.cern.ch/record/2217765['arXiv:1609.07125']arXiv:1609.07125Fast Evolution and Waveform Generator for Extreme-Mass-Ratio Inspirals in Equatorial-Circular Orbits
https://cds.cern.ch/record/2217758
In this paper we discuss the development of a fast and accurate waveform model for the quasi-circular orbital evolution of extreme-mass-ratio-inspirals (EMRIs). This model simply employs the data of a few numerical Teukoulsky-based energy fluxes and waveforms to fit out a set of polynomials for the entire fluxes and waveforms. These obtained polynomials are accurate enough in the entire evolution domain, and much more accurate than the resummation post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a black hole becomes large. The dynamical equation we adopted for orbital revolution is the effective-one-body (EOB) formalism. Because of the simplified expressions, the efficiency of calculating the orbital evolution with our polynomials is also better than the traditional method which uses the resummed PN analytical fluxes. Our model should be useful in calculation of waveform templates of EMRIs for the gravitational wave detectors such as the evolved Laser Interferometer Space Antenna (eLISA).Han, Wen-BiaoFri, 23 Sep 2016 07:08:07 GMT22 Sep 2016arXiv:1609.06817https://cds.cern.ch/record/2217758['arXiv:1609.06817']arXiv:1609.06817The Distribution of Dark and Luminous Matter in the Unique Galaxy Cluster Merger Abell 2146
https://cds.cern.ch/record/2217717
Abell 2146 ($z$ = 0.232) consists of two galaxy clusters undergoing a major merger. The system was discovered in previous work, where two large shock fronts were detected using the $\textit{Chandra X-ray Observatory}$, consistent with a merger close to the plane of the sky, caught soon after first core passage. A weak gravitational lensing analysis of the total gravitating mass in the system, using the distorted shapes of distant galaxies seen with ACS-WFC on $\textit{Hubble Space Telescope}$, is presented. The highest peak in the reconstruction of the projected mass is centred on the Brightest Cluster Galaxy (BCG) in Abell 2146-A. The mass associated with Abell 2146-B is more extended. Bootstrapped noise mass reconstructions show the mass peak in Abell 2146-A to be consistently centred on the BCG. Previous work showed that BCG-A appears to lag behind an X-ray cool core; although the peak of the mass reconstruction is centred on the BCG, it is also consistent with the X-ray peak given the resolution of the weak lensing mass map. The best-fit mass model with two components centred on the BCGs yields $M_{200}$ = 1.1$^{+0.3}_{-0.4}$$\times$10$^{15}$M$_{\odot}$ and 3$^{+1}_{-2}$$\times$10$^{14}$M$_{\odot}$ for Abell 2146-A and Abell 2146-B respectively, assuming a mass concentration parameter of $c=3.5$ for each cluster. From the weak lensing analysis, Abell 2146-A is the primary halo component, and the origin of the apparent discrepancy with the X-ray analysis where Abell 2146-B is the primary halo is being assessed using simulations of the merger.King, Lindsay JClowe, Douglas IColeman, Joseph ERussell, Helen RSantana, RebeccaWhite, Jacob ACanning, Rebecca E ADeering, Nicole JFabian, Andrew CLee, Brandyn ELi, BaojiuMcNamara, Brian RFri, 23 Sep 2016 07:06:01 GMT21 Sep 2016arXiv:1609.06734https://cds.cern.ch/record/2217717['arXiv:1609.06734']arXiv:1609.06734Upper bound on the center-of-mass energy of the collisional Penrose process
https://cds.cern.ch/record/2217708
Following the interesting work of Ba\~nados, Silk, and West [Phys. Rev. Lett. {\bf 103}, 111102 (2009)], it is repeatedly stated in the physics literature that the center-of-mass energy, ${\cal E}_{\text{c.m}}$, of two colliding particles in a maximally rotating black-hole spacetime can grow unboundedly. For this extreme scenario to happen, the particles have to collide at the black-hole horizon. In this paper we show that Thorne's famous hoop conjecture precludes this extreme scenario from occurring in realistic black-hole spacetimes. In particular, it is shown that a new (and larger) horizon is formed {\it before} the infalling particles reach the horizon of the original black hole. As a consequence, the center-of-mass energy of the collisional Penrose process is {\it bounded} from above by the simple scaling relation ${\cal E}^{\text{max}}_{\text{c.m}}/2\mu\propto(M/\mu)^{1/4}$, where $M$ and $\mu$ are respectively the mass of the central black hole and the proper mass of the colliding particles.Hod, ShaharFri, 23 Sep 2016 07:05:59 GMT21 Sep 2016arXiv:1609.06717https://cds.cern.ch/record/2217708['arXiv:1609.06717']arXiv:1609.06717Quantum State Effusion
https://cds.cern.ch/record/2217541
I give a scientific perspective, with a personal emphasis, on the seminal 1992 paper, "The quantum-state diffusion model applied to open systems", by Gisin and Percival.Wiseman, Howard MThu, 22 Sep 2016 06:26:34 GMT21 Sep 2016arXiv:1609.06572https://cds.cern.ch/record/2217541['arXiv:1609.06572']arXiv:1609.06572Rethinking Newton's $\textit{Principia}$
https://cds.cern.ch/record/2217500
It is widely accepted that the notion of an inertial frame is central to Newtonian mechanics and that the correct space-time structure underlying $\text{Newton's}$ methods in $\textit{Principia}$ is neo-Newtonian or Galilean space-time. I argue to the contrary that inertial frames are not needed in $\text{Newton's}$ theory of motion, and that the right space-time structure for $\text{Newton's}$ $\textit{Principia}$ requires the notion of parallelism of spatial directions at different times and nothing more.Saunders, SimonThu, 22 Sep 2016 06:26:26 GMT20 Sep 2016arXiv:1609.06130https://cds.cern.ch/record/2217500['arXiv:1609.06130']arXiv:1609.06130Tunnelling splitting in the phosphine molecule
https://cds.cern.ch/record/2217491
Splitting due to tunnelling via the potential energy barrier has played a significant role in the study of molecular spectra since the early days of spectroscopy. The observation of the ammonia doublet led to attempts to find a phosphine analogous, but these have so far failed due to its considerably higher barrier. Full dimensional, variational nuclear motion calculations are used to predict splittings as a function of excitation energy. Simulated spectra suggest that such splittings should be observable in the near infrared via overtones of the $\nu_2$ bending mode starting with $4\nu_2$.Sousa-Silva, ClaraTennyson, JonathanYurchenko, Sergey NThu, 22 Sep 2016 06:26:24 GMT20 Sep 2016arXiv:1609.06053https://cds.cern.ch/record/2217491['arXiv:1609.06053']arXiv:1609.06053Neutral and non-neutral collisionless plasma equilibria for twisted flux tubes: The Gold-Hoyle model in a background field
https://cds.cern.ch/record/2217489
We calculate exact one-dimensional collisionless plasma equilibria for a continuum of flux tube models, for which the total magnetic field is made up of the `force-free' Gold-Hoyle magnetic flux tube embedded in a uniform and anti-parallel background magnetic field. For a sufficiently weak background magnetic field, the axial component of the total magnetic field reverses at some finite radius. The presence of the background magnetic field means that the total system is not exactly force-free, but by reducing its magnitude the departure from force-free can be made as small as desired. The distribution function for each species is a function of the three constants of motion; namely the Hamiltonian and the canonical momenta in the axial and azimuthal directions. Poisson's Equation and Amp\`{e}re's Law are solved exactly, and the solution allows either electrically neutral or non-neutral configurations, depending on the values of the bulk ion and electron flows. These equilibria have possible applications in various solar, space and astrophysical contexts, as well as in the laboratory.Allanson, OWilson, FNeukirch, TThu, 22 Sep 2016 06:26:24 GMT20 Sep 2016arXiv:1609.06050https://cds.cern.ch/record/2217489['arXiv:1609.06050']arXiv:1609.06050How to distinguish conformational selection and induced fit based on chemical relaxation rates
https://cds.cern.ch/record/2217485
Protein binding often involves conformational changes. Important questions are whether a conformational change occurs prior to a binding event ('conformational selection') or after a binding event ('induced fit'), and how conformational transition rates can be obtained from experiments. In this article, we present general results for the chemical relaxation rates of conformational-selection and induced-fit binding processes that hold for all concentrations of proteins and ligands and, thus, go beyond the standard pseudo-first-order approximation of large ligand concentration. These results allow to distinguish conformational-selection from induced-fit processes - also in cases in which such a distinction is not possible under pseudo-first-order conditions - and to extract conformational transition rates of proteins from chemical relaxation data.Paul, FabianWeikl, Thomas RThu, 22 Sep 2016 06:26:24 GMT20 Sep 2016arXiv:1609.06021https://cds.cern.ch/record/2217485['arXiv:1609.06021']arXiv:1609.06021Nanotube-Terminated Zigzag Edge of Phosphorene formed by Self-Rolling Reconstruction
https://cds.cern.ch/record/2217481
Edge atomic configuration often plays an important role in dictating the properties of finite-sized two-dimensional (2D) materials. By performing ab initio calculations, we identify a highly stable zigzag edge of phosphorene, which is the most stable one among all the considered edges. Surprisingly, this highly stable edge exhibits a novel nanotube-like structure, which is topologically distinctively different from any previously reported edge reconstruction. We further show that this new edge type can form easily, with an energy barrier of only 0.234 eV. It may be the dominant edge type at room temperature in vacuum condition or even under low hydrogen gas pressure. The calculated band structure reveals that the reconstructed edge possesses a bandgap of 1.23 eV. It is expected that this newly found edge structure may stimulate more studies in uncovering other novel edge types and further exploring their practical applications.Gao, JunfengLiu, XiangjunZhang, GangZhang, Yong-WeiThu, 22 Sep 2016 06:26:24 GMT19 Sep 2016arXiv:1609.05997https://cds.cern.ch/record/2217481['arXiv:1609.05997']arXiv:1609.05997Systematic study on probable projectile-target combinations for the synthesis of the $^{302}$120 superheavy nucleus
https://cds.cern.ch/record/2217463
Probable projectile-target combinations for the synthesis of superheavy element $^{302}$120 have been studied taking Coulomb and proximity potential as the interaction barrier. The probabilities of compound nucleus formation, PCN for the projectile-target combinations found in the cold reaction valley of $^{302}$120 are estimated. At energies near and above the Coulomb barrier, we have calculated the capture, fusion and evaporation residue cross sections for the reactions of all the probable projectile-target combinations so as to predict the most promising projectile-target combinations for the synthesis of SHE $^{302}$120 in heavy ion fusion reactions. The calculated fusion and evaporation cross section for the more asymmetric (hotter) projectile-target combination is found to be higher than the less asymmetric (colder) combination. It can be seen from the nature of quasi-fission barrier height, mass asymmetry, probability of compound nucleus formation, survival probability and excitation energy, the systems $^{44}$Ar + $^{258}$No, $^{46}$Ar + $^{256}$No, $^{48}$Ca + $^{254}$Fm, $^{50}$Ca + $^{252}$Fm, $^{54}$Ti + $^{248}$Cf, $^{58}$Cr + $^{244}$Cm in the deep region I of cold reaction valley, and the systems $^{62}$Fe + $^{240}$Pu, $^{64}$Fe + $^{238}$Pu, $^{68}$Ni + $^{234}$U, $^{70}$Ni + $^{232}$U, $^{72}$Ni + $^{230}$U, $^{74}$Zn + $^{228}$Th in the other cold valleys are identified as the better projectile-target combinations for the synthesis of $^{302}$120. Our prediction on the synthesis of $^{302}$120 superheavy nuclei using the combinations $^{54}$Cr+$^{248}$Cm, $^{58}$Fe+$^{244}$Pu, $^{64}$Ni+$^{238}$U and $^{50}$Ti+$^{249}$Cf are compared with available experimental data and other theoretical predictions.Santhosh, K PSafoora, VThu, 22 Sep 2016 06:25:15 GMT21 Sep 2016arXiv:1609.06467https://cds.cern.ch/record/2217463['arXiv:1609.06467']arXiv:1609.06467New fermions in the bulk
https://cds.cern.ch/record/2217450
Spinor fields on 5-dimensional Lorentzian manifolds are classified, according to the geometric Fierz identities that involve their bilinear covariants. Based upon this classification that generalises the celebrated 4-dimensional Lounesto classification of spinor fields, new non-trivial classes of 5-dimensional spinor fields are, hence, found, with important potential applications regarding bulk fermions and their subsequent localisation on brane-worlds. In addition, quaternionic bilinear covariants are used to derive the quaternionic spin density, through the truncated exterior bundle. In order to accomplish a realisation of these new spinors, a Killing vector field is constructed on the horizon of 5-dimensional Kerr black holes. This Killing vector field is shown to reach the time-like Killing vector field at the spatial infinity, through a current 1-form density, constructed with the derived new spinor fields. The current density is, moreover, expressed as the f\"unfbein components, assuming a condensed form.de Brito, K P Sda Rocha, RoldaoThu, 22 Sep 2016 06:24:12 GMT21 Sep 2016arXiv:1609.06495https://cds.cern.ch/record/2217450['arXiv:1609.06495']arXiv:1609.06495Fragmentation Functions of neutral mesons $\pi^0$ and $k ^0$ with Laplace transform approach
https://cds.cern.ch/record/2217428
With an analytical solutions of DGLAP evolution equations based on the Laplace transform method , we find the fragmentation functions (FFs) of neutral mesons, $\pi^0$ and $k ^0$ at NLO approximation. We also calculated the total fragmentation functions of these mesons and compared them with experimental data and those from global fits. The results show a good agreements between our solutions and other models and also are compatible with experimental data.Taghavi-Shahri, FTehrani, S AtashbarZare, MThu, 22 Sep 2016 06:22:58 GMT23 Jun 2016arXiv:1609.06594https://cds.cern.ch/record/2217428['arXiv:1609.06594']arXiv:1609.06594Holographic phase transition probed by non-local observables
https://cds.cern.ch/record/2217379
From the viewpoint of holography, the phase structure of a 5-dimensional Reissner-Nordstr\"{o}m-AdS black hole is probed by the two point correlation function, Wilson loop, and entanglement entropy. As the case of thermal entropy, we find for all the probes, the black hole undergos a Hawking-Page phase transition, a first order phase transition and a second order phase transition successively before it reaches to a stable phase. In addition, for these probes, we find the equal area law for the first order phase transition is valid always and the critical exponent of the heat capacity for the second order phase transition coincides with that of the mean field theory regardless of the size of the boundary region.Zeng, Xiao-XiongLi, Li-FangThu, 22 Sep 2016 06:20:03 GMT21 Sep 2016arXiv:1609.06535https://cds.cern.ch/record/2217379['arXiv:1609.06535']arXiv:1609.06535Breakdown of the equivalence between active gravitational mass and energy for a quantum body
https://cds.cern.ch/record/2217375
We determine active gravitational mass operator of the simplest composite quantum body - a hydrogen atom - within the semiclassical approach to the Einstein equation for a gravitational field. We show that the expectation value of the mass is equivalent to energy for stationary quantum states. On the other hand, it occurs that, for quantum superpositions of stationary states with constant expectation values of energy, the expectation values of the gravitational mass exhibit time-dependent oscillations. This breaks the equivalence between active gravitational mass and energy and can be observed as a macroscopic effect for a macroscopic ensemble of coherent quantum states of the atoms. The corresponding experiment could be the first direct observation of quantum effects in General Relativity.Lebed, Andrei GThu, 22 Sep 2016 06:20:03 GMT20 Sep 2016arXiv:1609.06358https://cds.cern.ch/record/2217375['arXiv:1609.06358']arXiv:1609.06358Scalar Quasinormal Modes of Anti-de Sitter Static Spacetime in Horava-Lifshitz Gravity with $U(1)$ Symmetry
https://cds.cern.ch/record/2217365
In this paper, we investigate the scalar quasinormal modes of Ho\v{r}ava-Lifshitz theory with $U(1)$ symmetry in static Anti-de Sitter spacetime. The static planar and spherical black hole solutions in lower energy limit are derived in non-projectable Ho\v{r}ava-Lifshitz gravity. The equation of motion of a scalar field is obtained, and is utilized to study the quasinormal modes of massless scalar particles. We find that the effect of Ho\v{r}ava-Lifshitz correction is to increase the quasinormal period as well as to slow down the decay of the oscillation magnitude. Besides, the scalar field could be unstable when the correction becomes too large.Lin, KaiQian, Wei-LiangPavan, A BThu, 22 Sep 2016 06:20:02 GMT19 Sep 2016arXiv:1609.05963https://cds.cern.ch/record/2217365['arXiv:1609.05963']arXiv:1609.05963SPHERE IRDIS and IFS astrometric strategy and calibration
https://cds.cern.ch/record/2217358
We present the current results of the astrometric characterization of the VLT planet finder SPHERE over 2 years of on-sky operations. We first describe the criteria for the selection of the astrometric fields used for calibrating the science data: binaries, multiple systems, and stellar clusters. The analysis includes measurements of the pixel scale and the position angle with respect to the North for both near-infrared subsystems, the camera IRDIS and the integral field spectrometer IFS, as well as the distortion for the IRDIS camera. The IRDIS distortion is shown to be dominated by an anamorphism of 0.60+/-0.02% between the horizontal and vertical directions of the detector, i.e. 6 mas at 1". The anamorphism is produced by the cylindrical mirrors in the common path structure hence common to all three SPHERE science subsystems (IRDIS, IFS, and ZIMPOL), except for the relative orientation of their field of view. The current estimates of the pixel scale and North angle for IRDIS are 12.255+/-0.009 milliarcseconds/pixel for H2 coronagraphic images and -1.75+/-0.08 deg. Analyses of the IFS data indicate a pixel scale of 7.46+/-0.02 milliarcseconds/pixel and a North angle of -102.18+/-0.13 deg. We finally discuss plans for providing astrometric calibration to the SPHERE users outside the instrument consortium.Maire, Anne-LiseLanglois, MaudDohlen, KjetilLagrange, Anne-MarieGratton, RaffaeleChauvin, GaelDesidera, SilvanoGirard, Julien HMilli, JulienVigan, ArthurZins, GerardDelorme, PhilippeBeuzit, Jean-LucClaudi, Riccardo UFeldt, MarkusMouillet, DavidPuget, PascalTuratto, MassimoWildi, FrancoisThu, 22 Sep 2016 06:16:41 GMT21 Sep 2016arXiv:1609.06681https://cds.cern.ch/record/2217358['arXiv:1609.06681']arXiv:1609.06681Testing the asteroseismic scaling relations for Red Giants with Eclipsing Binaries Observed by Kepler
https://cds.cern.ch/record/2217355
Given the potential of ensemble asteroseismology for understanding fundamental properties of large numbers of stars, it is critical to determine the accuracy of the scaling relations on which these measurements are based. From several powerful validation techniques, all indications so far show that stellar radius estimates from the asteroseismic scaling relations are accurate to within a few percent. Eclipsing binary systems hosting at least one star with detectable solar-like oscillations constitute the ideal test objects for validating asteroseismic radius and mass inferences. By combining radial-velocity measurements and photometric time series of eclipses, it is possible to determine the masses and radii of each component of a double-lined spectroscopic binary. We report the results of a four-year radial-velocity survey performed with the \'echelle spectrometer of the Astrophysical Research Consortium's 3.5-m telescope and the APOGEE spectrometer at Apache Point Observatory. We compare the masses and radii of 10 red giants obtained by combining radial velocities and eclipse photometry with the estimates from the asteroseismic scaling relations. We find that the asteroseismic scaling relations overestimate red-giant radii by about 5% on average and masses by about 15% for stars at various stages of red-giant evolution. Systematic overestimation of mass leads to underestimation of stellar age, which can have important implications for ensemble asteroseismology used for Galactic studies. As part of a second objective, where asteroseismology is used for understanding binary systems, we confirm that oscillations of red giants in close binaries can be suppressed enough to be undetectable, an hypothesis that was proposed in a previous work.Gaulme, PatrickMcKeever, JeanJackiewicz, JasonRawls, Meredith RCorsaro, EnricoMosser, BenoitSouthworth, JohnMahadevan, SuvrathBender, ChadDeshpande, RohitThu, 22 Sep 2016 06:16:40 GMT21 Sep 2016arXiv:1609.06645https://cds.cern.ch/record/2217355['arXiv:1609.06645']arXiv:1609.06645Terrestrial Planet Formation from an Annulus
https://cds.cern.ch/record/2217353
It has been shown that some aspects of the terrestrial planets can be explained, particularly the Earth/Mars mass ratio, when they form from a truncated disk with an outer edge near 1.0 au (Hansen 2009). This has been previously modeled starting from an intermediate stage of growth utilizing pre-formed planetary embryos. We present simulations that were designed to test this idea by following the growth process from km-sized objects located between 0.7 to 1.0 au up to terrestrial planets. The simulations explore initial conditions where the solids in the disk are planetesimals with radii initially between 3 and 300 km, alternately including effects from a dissipating gaseous solar nebula and collisional fragmentation. We use a new Lagrangian code known as LIPAD (Levison et al. 2012), which is a particle-based code that models the fragmentation, accretion and dynamical evolution of a large number of planetesimals, and can model the entire growth process from km-sizes up to planets. A suite of large (Mars mass) planetary embryos is complete in only 1 Myr, containing most of the system mass. A quiescent period then persists for 10-20 Myr characterized by slow diffusion of the orbits and continued accretion of the remaining planetesimals. This is interupted by an instability that leads to embryos crossing orbits and embyro-embryo impacts that eventually produce the final set of planets. While this evolution is different than that found in other works exploring an annulus, the final planetary systems are similar, with roughly the correct number of planets and good Mars-analogs.Walsh, Kevin JLevison, Hal FThu, 22 Sep 2016 06:16:40 GMT21 Sep 2016arXiv:1609.06639https://cds.cern.ch/record/2217353['arXiv:1609.06639']arXiv:1609.06639Developing an integrated concept for the E-ELT Multi-Object Spectrograph (MOSAIC): design issues and trade-offs
https://cds.cern.ch/record/2217349
We present a discussion of the design issues and trade-offs that have been considered in putting together a new concept for MOSAIC, the multi-object spectrograph for the E-ELT. MOSAIC aims to address the combined science cases for E-ELT MOS that arose from the earlier studies of the multi-object and multi-adaptive optics instruments. MOSAIC combines the advantages of a highly-multiplexed instrument targeting single-point objects with one which has a more modest multiplex but can spatially resolve a source with high resolution (IFU). These will span across two wavebands: visible and near-infrared.Rodrigues, MyriamDalton, GavinFitzsimons, EwanChemla, FannyMorris, TimHammer, FrancoisPuech, MathieuEvans, ChristopherJagourel, PascalThu, 22 Sep 2016 06:16:39 GMT21 Sep 2016arXiv:1609.06610https://cds.cern.ch/record/2217349['arXiv:1609.06610']arXiv:1609.06610Hawking-like radiation and the density matrix for an infalling observer during gravitational collapse
https://cds.cern.ch/record/2217344
We study time-dependant Hawking-like radiation as seen by an infalling observer during gravitational collapse of a thin shell. We calculate the occupation number of particles whose frequencies are measured in the proper time of an infalling observer in Eddington-Finkelstein coordinates. We solve the equations for the whole process from the beginning of the collapse till the moment when the collapsing shell reaches zero radius. The radiation distribution is not thermal in the whole frequency regime, but it is approximately thermal for the wavelengths of the order of the Schwarzschild radius of the collapsing shell. After the Schwarzschild radius is crossed, the temperature increases without limits as the singularity is approached. We also calculate the density matrix associated with this radiation. It turns out that the off-diagonal correlation terms to the diagonal Hawking's leading order terms are very important. While the trace of the diagonal (Hawking's) density matrix squared decreases during the evolution, the trace of the total density matrix squared remains unity at all times and all frequencies.Saini, AnshulStojkovic, DejanThu, 22 Sep 2016 06:16:36 GMT20 Sep 2016arXiv:1609.06584https://cds.cern.ch/record/2217344['arXiv:1609.06584']arXiv:1609.06584