Miracle-dz/UniFAR-FTUs huggingface dataset:
Thermodynamic analysis of quantum light amplification

Thermodynamics of a three-level maser was studied in the pioneering work of Scovil and Schulz-DuBois [Phys. Rev. Lett. 2, 262 (1959)]. In this work we consider the same three-level model, but treat both the matter and the light quantum mechanically. Specifically, we analyze an extended (three-level) dissipative (ED) Jaynes-Cummings model (JCM) within the framework of a quantum heat engine, using formulas for heat flux and power in bipartite systems introduced in our previous work [E. Boukobza and D. J. Tannor Phys. Rev. A 74, 063823 (2006)] Amplification of the selected cavity mode occurs even in this simple model, as seen by a positive steady state power. However, initial field coherence is lost, as seen by the decaying off-diagonal field density matrix elements, and by the Husimi-Kano Q function. We show that after an initial transient time the field's entropy rises linearly during the operation of the engine, which we attribute to the dissipative nature of the evolution and not to matter-field entanglement. We show that the second law of thermodynamics is satisfied in two formulations (Clausius, Carnot) and that the efficiency of the ED JCM heat engine agrees with that defined intuitively by Scovil and Schulz-DuBois. Finally, we compare themore » steady state heat flux and power of the fully quantum model with the semiclassical counterpart of the ED JCM, and derive the engine efficiency formula of Scovil and Schulz-DuBois analytically from fundamental thermodynamic fluxes. « less
The Metallicity Dependence of the CO-to-H2 Conversion Factor from Observations of Local Group Galaxies

Six additional molecular clouds have been mapped in the nearby metal-poor dwarf irregular galaxy IC 10 using the Owens Valley Millimeter-Wave Interferometer. Since a good distance measurement is now available for IC 10, it is possible to measure accurately the CO-to-H2 conversion factor in this galaxy. The result for IC 10 is combined with published data for four other Local Group galaxies (M31, M33, NGC 6822, and the SMC) to trace the dependence of the CO-to-H2 conversion factor on the oxygen abundance using a well-defined sample of extragalactic giant molecular clouds. These data show conclusively that the CO-to-H2 conversion factor increases as the metallicity of the host galaxy decreases, with the conversion factor increasing by a factor of 4.6 for a factor of 10 decrease in metallicity. This new calibration of the effect of metallicity on the CO-to-H2 conversion factor will allow more accurate molecular gas masses to be obtained in galaxies and regions of galaxies with moderately low metallicity.
Electron hydrodynamics with a polygonal Fermi surface

Recent experiments have observed hints of hydrodynamic electron flow in a number of materials, not all of which have a simple Fermi surface. Motivated by such experiments in $\mathrm{PdCoO}_2$, a quasi-two-dimensional material whose Fermi surface is a rounded hexagon, we develop a simple model for the low temperature kinetics and hydrodynamics of a two-dimensional Fermi liquid with a polygonal Fermi surface. A geometric effect leads to a finite number of additional long-lived quasihydrodynamic "imbalance" modes and corresponding qualitative changes in transport at the ballistic-to-hydrodynamic crossover. In the hydrodynamic limit, we find incoherent diffusion and a new dissipative component of the viscosity tensor arising from the explicit breaking of rotational invariance by the Fermi surface. We also calculate the conductance of narrow channels across the ballistic-to-hydrodynamic crossover and demonstrate the possibility of non-monotonic temperature and width dependence in the channel conductance. We revisit experimental evidence for hydrodynamic flow in $\mathrm{PdCoO}_2$ in the context of these results.
Probing the π0 spectrum at high-x in proton-Air interactions at ultra-high energies

The average number of muons in air showers and its connection with shower development has been studied extensively in the past. With the upcoming detector upgrades, UHECR observatories will be able to probe higher moments of the distribution of the number of muons. Here a study of the physics of the fluctuations of the muon content is presented. In addition to proving that the fluctuations must be dominated by the first interactions, we show that low-Nμ tail of the shower-to-shower distribution of the number of muons is determined by the high-xL region of the production cross-section of neutral pions in the first interaction.
Can gravity appear due to polarization of instantons in the SO(4) gauge theory?

Conventional non-Abelian SO(4) gauge theory is able to describe gravity provided the gauge ﬁeld possesses a speciﬁc polarized vacuum state. In this vacuum the instantons and antiinstantons have a preferred direction of orientation. Their orientation plays the role of the order parameter for the polarized phase of the gauge ﬁeld. The interaction of a weak and smooth gauge ﬁeld with the polarized vacuum is described by an eﬀective long-range action which is identical to the Hilbert action of general relativity. In the classical limit this action results in the Einstein equations of general relativity. Gravitational waves appear as the mode describing propagation of the gauge ﬁeld which strongly interacts with the oriented instantons. The Newton gravitational constant describes the density of the considered phase of the gauge ﬁeld. The radius of the instantons under consideration is comparable with the Planck radius.
Gravity as an SU(1, 1) gauge theory in four dimensions

We start with the Hamiltonian formulation of the first order action of pure gravity with a full sl(2,C) internal gauge symmetry. We make a partial gauge-fixing which reduces sl(2,C) to its sub-algebra su(1,1). This case corresponds to a splitting of the space-time M=Σ×R where Σ inherits an arbitrary Lorentzian metric of signature (−, +, +). Then, we find a parametrization of the phase space in terms of an su(1,1) commutative connection and its associated conjugate electric field. Following the techniques of loop quantum gravity, we start the quantization of the theory and we consider the kinematical Hilbert space on a given fixed graph Γ whose edges are colored with unitary representations of su(1,1). We compute the spectrum of area operators acting on the kinematical Hilbert space: we show that space-like areas have discrete spectra, in agreement with usual su(2) loop quantum gravity, whereas time-like areas have continuous spectra. We conclude on the possibility to make use of this formulation of gravity to construct a holographic description of black holes in the framework of loop quantum gravity.
Modelling Association Football Scores and Inefficiencies in the Football Betting Market

A parametric model is developed and fitted to English league and cup football data from 1992 to 1995. The model is motivated by an aim to exploit potential inefficiencies in the association football betting market, and this is examined using bookmakers' odds from 1995 to 1996. The technique is based on a Poisson regression model but is complicated by the data structure and the dynamic nature of teams' performances. Maximum likelihood estimates are shown to be computationally obtainable, and the model is shown to have a positive return when used as the basis of a betting strategy.
Long-term variability in the X-ray emission of RX J0720.4-3125

We detect a gradual, long-term change in the shape of the X-ray spectrum of the isolated neutron star RX J0720.4-3125, such that the spectrum of the source can no longer be described as a blackbody spectrum. The change is accompanied by an energy-dependent change in the pulse profile. If the X-ray emission is influenced by the magnetic field of the pulsar, these changes in spectral shape may point to precession of the neutron star.
The Star Formation Histories of Four Fields Spanning the Minor Axis of NGC 6822

The star formation histories of four fields within the Local Group dwarf irregular galaxy NGC 6822 are presented. Each of the fields was imaged by the WFPC2 aboard the Hubble Space Telescope and were used to obtain VI color-magnitude diagrams for each field reaching V ≃ 26. The magnitude of the tip of the red giant branch and the red clump were used to determine distances to NGC 6822 that are consistent with previous ground-based measurements. The distance, extinction, and star formation history were also determined by fitting the entire color-magnitude diagram in each field. The distances from these fits are consistent with the other determinations within the estimated errors once the systematic effects of uncertainties in the age-metallicity relation are taken into account. The extinction varies among the four fields, from approximately the foreground Galactic value to ≈0.4 mag higher in V, and roughly correlates with the 60 μm surface brightness. The star formation histories in the four fields are similar for ages ≳1 Gyr and are relatively constant or somewhat increasing with time. These old star formation rates are comparable to that expected from the typical gas surface densities at these galactocentric radii and suggest that no large-scale redistribution of gas or stars is required to account for the inferred star formation rates. Three of the fields show a drop of a factor of ∼2–4 in the star formation rate about 600 Myr ago, while the remaining field centered on the bar shows an increase.
The Tully–Fisher relation for flat galaxies

We construct a multiparametric Tully-Fisher (TF) relation for a large sample of edge-on galaxies from the Revised Flat Galaxy Catalog using HI data from the EDD database and parameters from the EGIS catalog. We incorporate a variety of additional parameters including structural parameters of edge-on galaxies in different bandpasses. Besides the rotation curve maximum, only the HI-to-optical luminosity ratio and optical colours play a statistically significant role in the multiparametric TF relation. We are able to decrease the standard deviation of the multiparametric TF relation down to 0.32 mag, which is at the level of best modern samples of galaxies used for studies of the matter motion in the Universe via the TF-relation.
Broad infrared line emission from the nuclei of Seyfert 2 galaxies

Les observations spectroscopiques a λ/δ λ = 300 de la raie de recombinaison de l'hydrogene β Paschen des galaxies RX NGC 5506 et A 0945-30 et de la galaxie de Seyfert de type 2 NGC 4388 sont presentees
Liquid crystal Skyrmions can swim

Topologically nontrivial field configurations called "baby skyrmions" behave like particles and give origins to the field of skyrmionics that promises racetrack memory and other technological applications. Unraveling the non-equilibrium behavior of such topological solitons is a challenge. We realize baby skyrmions in a chiral liquid crystal and, using numerical modeling and polarized video microscopy, demonstrate electrically driven squirming motion. We reveal the intricate details of non-equilibrium topology-preserving textural changes driving this behavior. Direction of the skyrmion's motion is robustly controlled in a plane orthogonal to the applied field and can be reversed by varying frequency. Our findings may spur a new paradigm of soliton dynamics in soft matter, with a rich interplay between topology, chirality, and orientational viscoelasticity.
Strain Effect in Highly‐Doped n‐Type 3C‐SiC‐on‐Glass Substrate for Mechanical Sensors and Mobility Enhancement

This work reports the strain effect on the electrical properties of highly doped n‐type single crystalline cubic silicon carbide (3C‐SiC) transferred onto a 6‐inch glass substrate employing an anodic bonding technique. The experimental data shows high gauge factors of −8.6 in longitudinal direction and 10.5 in transverse direction along the [100] orientation. The piezoresistive effect in the highly doped 3C‐SiC film also exhibits an excellent linearity and consistent reproducibility after several bending cycles. The experimental result is in good agreement with the theoretical analysis based on the phenomenon of electron transfer between many valleys in the conduction band of n‐type 3C‐SiC. Our finding for the large gauge factor in n‐type 3C‐SiC coupled with the elimination of the current leak to the insulated substrate could pave the way for the development of single crystal SiC‐on‐glass based MEMS applications.
Detachment of nanotubes from a polymer matrix

A technique to investigate the adhesion of carbon nanotubes to a polymer matrix is described. Carbon nanotubes bridging across holes in an epoxy matrix have been drawn out using the tip of a scanning probe microscope while recording the forces involved. A full force-displacement trace could be recorded and correlated with transmission electron micrographs observations prior and subsequent to the tip action. Based on these experiments, an approximate calculation of the nanotube-polymer interfacial shear strength has been performed.
Relativistic stars in Randall-Sundrum gravity

The nonlinear behavior of Randall-Sundrum gravity with one brane is examined. Due to the noncompact extra dimension, the perturbation spectrum has no mass gap, and the long wavelength effective theory is only understood perturbatively. The full five-dimensional Einstein equations are solved numerically for static, spherically symmetric matter localized on the brane, yielding regular geometries in the bulk with axial symmetry. An elliptic relaxation method is used, allowing both the brane and asymptotic radiation boundary conditions to be simultaneously imposed. The same data that specifies stars in four-dimensional gravity, uniquely constructs a five-dimensional solution. The algorithm performs best for small stars (radius less than the AdS length) yielding highly nonlinear solutions, core photons being redshifted by up to $\mathcal{Z}\ensuremath{\simeq}12. $ An upper mass limit is observed for these small stars, and the geometry shows no global pathologies. The geometric perturbation is shown to remain localized near the brane at high densities, the confinement interestingly increasing for both small and large stars as the upper mass limit is approached. Furthermore, the static spatial sections are found to be approximately conformal to those of AdS. We show that the intrinsic geometry of large stars, with a radius several times the AdS length, is described by four-dimensional general relativity far past the perturbative regime, the largest stars being tested up to a core redshift of $\mathcal{Z}\ensuremath{\simeq}2.1. $ This indicates that the nonlinear long wavelength effective action remains local, even though the perturbation spectrum has no mass gap. The implication is that Randall-Sundrum gravity, with localized brane matter, reproduces relativistic astrophysical solutions, such as neutron stars and massive black holes, consistent with observation.
Hybrid Automata with Finite Mutual Simulations

Many decidability results for hybrid automata rely upon the finite region bisimulation of timed automata [AD94]. Rectangular automata do not have finite bisimulations [Hen95], yet have many decidable verification problems [PV94,HKPV95]. We prove that every two-dimensional rectangular automaton A with positive-slope variables has a finite mutual simulation relation, which is the intersection of the region bisimulations defined by the extremal slopes of the variables of A. While the mutual simulation is infinite for two-dimensional automata with one variable taking both positive and negative slopes, it forms a regular tesselation of the plane, and therefore can be encoded by one counter. As a corollary, we obtain the decidability of model checking linear temporal logic on these automata.
A Wide-field Photometric Survey of Globular Clusters in the Peculiar Early-type Galaxy M85

We survey globular clusters (GCs) in M85 using ugi-band images of a 1° × 1° field obtained with the MegaCam at the 3.6 m Canada–France–Hawaii Telescope. We identify 1318 GC candidates with 20.0 mag < g0 < 23.5 mag in the entire survey region. Their radial number density profile is well fit by a Sérsic profile with n = and effective radius Re,GCS = 4. ′14 (=22 kpc), showing that the candidates at R < 20′ are mostly genuine GCs in M85. We estimate the total number of GCs, N(total) = , and the specific frequency, . The overall color distribution of the GCs in M85 is bimodal, but the GCs in the central region at R < 2′ do not show a bimodal distribution clearly. The radial number density profile and surface number density map of the blue GCs (BGCs) show more extended structures than those of the red GCs (RGCs). The spatial distributions of both BGCs and RGCs are elongated, similar to that of the galaxy stellar light. The number fraction of the RGCs in the central region is much smaller compared to those in other early-type galaxies of similar luminosity. The mean (g − i)0 color of the RGCs in M85 is about 0.1 mag bluer than typical values for other Virgo early-type galaxies of similar luminosity, indicating that a significant fraction of the RGCs in M85 may be younger than typical GCs. These results indicate that M85 might have undergone a major wet merger recently.
Supplemental Material : Optomechanically Induced Birefringence and Faraday Effect

Robert Duggan,1, ∗ Javier del Pino,2, ∗ Ewold Verhagen,2 and Andrea Alù1, 3, 4, 5 Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX 78712, USA Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands Photonics Initiative, Advanced Science Research Center, City University of New York, NY 10031, USA Physics Program, Graduate Center, City University of New York, NY 10016, USA Department of Electrical Engineering, City College of The City University of New York, NY 10031, USA†
The Space-Time Lorentz Transformation: Relativity of Simultaneity is Incompatible with Translational Invariance

Observations of the apparent times and positions of moving clocks as predicted by both `non-local' and `local' Lorentz Transformations are considered. Only local transformations respect translational invariance. Such transformations change temporal but not spatial intervals, so breaking space time exchange symmetry and forbidding relativity of simultaneity and length contraction. A satellite cesium clock experiment to test these predictions is proposed.
Communicating without shared reference frames

We generalize a quantum communication protocol introduced by Bartlett et al. [New. J. Phys. 11, 063013 (2009)] in which two parties communicating do not share a classical reference frame, to the case where changes of their reference frames form a one-dimensional noncompact Lie group. Alice sends to Bob the state $\rho_R \otimes \rho_S$, where $\rho_S$ is the state of the system Alice wishes to communicate and $\rho_R$ is the state of an ancillary system serving as a token of her reference frame. Because Bob is ignorant of the relationship between his reference frame and Alice's, he will describe the state $\rho_R \otimes \rho_S$ as an average over all possible reference frames. Bob measures the reference token and applies a correction to the system Alice wished to communicate conditioned on the outcome of the measurement. The recovered state $\rho_S'$ is decohered with respect to $\rho_S$, the amount of decoherence depending on the properties of the reference token $\rho_R$. We present an example of this protocol when Alice and Bob do not share a reference frame associated with the one-dimensional translation group and use the fidelity between $\rho_S$ and $\rho_S'$ to quantify the success of the recovery operation.
X-ray mapping of the stellar wind in the binary PSR J2032+4127/MT91 213

PSR J2032+4127 is a young and rapidly rotating pulsar on a highly eccentric orbit around the high-mass Be star MT91 213. X-ray monitoring of the binary system over an ~4000 d period with Swift has revealed an increase of the X-ray luminosity which we attribute to the synchrotron emission of the shocked pulsar wind. We use Swift X-ray observations to infer a clumpy stellar wind with r-2 density profile and constrain the Lorentz factor of the pulsar wind to 105
Pressure Balance and Intrabinary Shock Stability in Rotation-powered-state Redback and Transitional Millisecond Pulsar Binary Systems

A number of low-mass millisecond pulsar (MSP) binaries in their rotation-powered state exhibit double-peaked X-ray orbital modulation centered at inferior pulsar conjunction. This state, which has been known to persist for years, has recently been interpreted as emission from a shock that enshrouds the pulsar. However, the pressure balance for such a configuration is a crucial unresolved issue. We consider two scenarios for pressure balance: a companion magnetosphere and stellar mass loss with gas dominance. It is found that the magnetospheric scenario requires several kilogauss poloidal fields for isobaric surfaces to enshroud the MSP, as well as for the magnetosphere to remain stable if there is significant mass loss. For the gas-dominated scenario, it is necessary that the companion wind loses angular momentum prolifically as an advection- or heating-dominated flow. Thermal bremsstrahlung cooling in the flow may be observable as a UV to soft X-ray component independent of orbital phase if the mass rate is high. We formulate the general requirements for shock stability against gravitational influences in the pulsar rotation-powered state for the gas-dominated scenario. We explore stabilizing mechanisms, principally irradiation feedback, which anticipates correlated shock emission and companion variability and predicts Fγ/FX ≲ 14 for the ratio of pulsar magnetospheric γ-ray to total shock soft-to-hard X-ray fluxes. This stability criterion implies an unbroken extension of X-ray power-law emission to hundreds of keV for some systems. We explore observational discriminants between the gas-dominated and magnetospheric scenarios, motivating contemporaneous radio through γ-ray monitoring of these systems.
The European Large Area ISO Survey - I. Goals, definition and observations

We describe the European Large Area ISO Survey (ELAIS). ELAIS was the largest single Open Time project conducted by ISO, mapping an area of 12deg^2 at 15μm with ISOCAM and at 90μm with ISOPHOT. Secondary surveys in other ISO bands were undertaken by the ELAIS team within the fields of the primary survey, with 6deg^2 being covered at 6. 7μm and 1deg^2 at 175μm. This paper discusses the goals of the project and the techniques employed in its construction, as well as presenting details of the observations carried out, the data from which are now in the public domain. We outline the ELAIS `preliminary analysis' which led to the detection of over 1000 sources from the 15 and 90-μm surveys (the majority selected at 15μm with a flux limit of ~3mJy), to be fed into a ground-based follow-up campaign, as well as a programme of photometric observations of detected sources using both ISOCAM and ISOPHOT. We detail how the ELAIS survey complements other ISO surveys in terms of depth and areal coverage, and show that the extensive multi-wavelength coverage of the ELAIS fields resulting from our concerted and on-going follow-up programme has made these regions amongst the best studied areas of their size in the entire sky, and, therefore, natural targets for future surveys. This paper accompanies the release of extremely reliable subsets of the `preliminary analysis' products. Subsequent papers in this series will give further details of our data reduction techniques, reliability and completeness estimates and present the 15- and 90-μm number counts from the `preliminary analysis', while a further series of papers will discuss in detail the results from the ELAIS `final analysis', as well as from the follow-up programme.