Miracle-dz/UniFAR-FTUs huggingface dataset:
Lack of time dilation in type Ia supernovae and Gamma-Ray Bursts

A fundamental property of any expanding universe is that any time dependent characteristics of distant objects must appear to scale by the factor $(1+z$). This is called time dilation. Light curves of type Ia supernovae and the duration of Gamma-Ray Bursts (GRB) are the only observations that can directly measure time dilation over a wide range of redshifts. An analysis of raw observations of type Ia supernovae light curves shows that their widths are proportional to $(1+z)^{(0.088\pm0.036)}$. Analysis of the duration of GRB show that they are proportional to $(1+z)^{(0.25\pm0.16)}$. Both are consistent with no time dilation and inconsistent with a factor of $(1+z$) which implies that the universe is static. In addition it is shown that the standard method for calibrating the type Ia supernovae light curves (SALT2) is flawed, which explains why this lack of time dilation has not been previously observed.
The cosmic evolution of magnesium isotopes

The abundance of magnesium in the interstellar medium is a powerful probe of star formation processes over cosmological time-scales. Magnesium has three stable isotopes, ^24Mg, ^25Mg, and ^26Mg, which can be produced in both massive and intermediate-mass (IM) stars with masses between 2 and 8 M_⊙. In this work, we use constraints on the cosmic star formation rate density (SFRD) and explore the role and mass range of IM stars using the observed isotopic ratios. We compare several models of stellar nucleosynthesis with metallicity-dependent yields and also consider the effect of rotation on the yields of massive stars and its consequences on the evolution of the Mg isotopes. We use a cosmic evolution model updated with new observational SFRD data and new reionization constraints coming from 2018 Planck Collaboration determinations. We find that the main contribution of ^24Mg comes from massive stars whereas ^25Mg and ^26Mg come from IM stars. To fit the observational data on magnesium isotopic ratios, an additional IM SFRD component is preferred. Moreover, the agreement between model and data is further improved when the range of IM masses is narrowed towards higher masses (5–8 M_⊙). While some rotation also improves the fit to data, we can exclude the case where all stars have high rotational velocities due to an overproduction of ^26Mg.
Second-order coherence of superradiance from a Bose-Einstein condensate

(Received 23 December 2013; published 16 July 2014)Wehavemeasuredthetwo-particlecorrelationfunctionofatomsfromaBose-Einsteincondensateparticipatingin a superradiance process, which directly reﬂects the second-order coherence of the emitted light. We comparethis correlation function with that of atoms undergoing stimulated emission. Whereas the stimulated processproduces correlations resembling those of a coherent state, we ﬁnd that superradiance, even in the presenceof strong gain, shows a correlation function close to that of a thermal state, just as for ordinary spontaneousemission.DOI: 10.1103/PhysRevA.90. 013615 PACS number(s): 03
High nitrogen-vacancy density diamonds for magnetometry applications

V. M. Acosta, E. Bauch, 2 M. P. Ledbetter, C. Santori, K. -M. C. Fu, P. E. Barclay, R. G. Beausoleil, H. Linget, J. F. Roch, F. Treussart, S. Chemerisov, W. Gawlik, and D. Budker 8, 9 1 Department of Physics, University of California, Berkeley, CA 94720-7300 2 Technische Universität Berlin, Hardenbergstraÿe 28, 10623 Berlin, Germany 3 Hewlett-Packard Laboratories, 1501 Page Mill Rd., Palo Alto, CA 94304 4 Ecole Normale Supérieure de Cachan, 61 Avenue du Président Wilson, 94235 Cachan CEDEX, France 5 Laboratoire de Photonique Quantique et Moléculaire (CNRS UMR 8537), Ecole Normale Supérieure de Cachan, 61 Avenue du Président Wilson, 94235 Cachan CEDEX, France 6 Argonne National Laboratory, Argonne, IL, 60439, U.S.A. 7 Center for Magneto-Optical Research, Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, USA budker@berkeley.edu (Dated: July 31, 2009)
Cracking of general relativistic anisotropic polytropes

We discuss the effect that small fluctuations of local anisotropy of pressure, and energy density, may have on the occurrence of cracking in spherical compact objects, satisfying a polytropic equation of state. Two different kind of polytropes are considered. For both, it is shown that departures from equilibrium may lead to the appearance of cracking, for a wide range of values of the parameters defining the polytrope. Prospective applications of the obtained results, to some astrophysical scenarios, are pointed out.
Gravitational tides and dwarf spheroidal galaxies

The effect of the local environment on the evolution of dwarf spheroidal galaxies is poorly understood. We have undertaken a suite of simulations to investigate the tidal impact of the Milky Way on the chemodynamical evolution of dwarf spheroidals that resemble present day classical dwarfs using the SPH code GEAR. After simulating the models through a large parameter space of potential orbits, the resulting properties are compared with observations from a dynamical point of view, and from the, often neglected, chemical point of view. In general, we find that tidal effects quench the star formation even inside gas-endowed dwarfs. This quenching may produce the radial distribution of dwarf spheroidals from the orbits seen within large cosmological simulations. We also find that the metallicity gradient within a dwarf is gradually erased through tidal interactions as stellar orbits move to higher radii. The model dwarfs also shift to higher /L ratios, but only when they lose greater than or similar to 20% of stellar mass.
Calibrating dark energy

Exploring the diversity of dark energy dynamics, we discover a calibration relation, a uniform stretching of the amplitude of the equation of state time variation with scale factor. This defines homogeneous families of dark energy physics. The calibration factor has a close relation to the standard time variation parameter wa, and we show that the new, calibrated wa describes observables, i.e. distance and Hubble parameter as a function of redshift, typically to an accuracy level of 10−3. We discuss implications for figures of merit for dark energy science programs.
Analytical study of mismatched complementary media

An analytical framework based on multiple scattering theory is established for analyzing the mismatched case of complementary media (CM) interacting with arbitrarily situated obstacles. The CM-based devices of a superlens and superscatterer are discussed. The cancellation mechanism of the mismatched CM is studied. In addition, numerical results are provided for illustration. Detailed analysis shows that optical cancellation effects rely on specific conditions. Specifically, we studied the mismatched CM with perfect electrical conductor objects and presented its equivalence models.
Grape leaf disease detection based on attention mechanisms

: Prevention and control of grape diseases is the key measure to ensure grape yield. In order to improve the precision of grape leaf disease detection, in this study, Squeeze-and-Excitation Networks (SE), Efficient Channel Attention (ECA), and Convolutional Block Attention Module (CBAM) attention mechanisms were introduced into Faster Region-based Convolutional Neural Networks (R-CNN), YOLOx, and single shot multibox detector (SSD), to enhance important features and weaken unrelated features and ensure the real-time performance of the model in improving its detection precision. The study showed that Faster R-CNN, YOLOx, and SSD models based on different attention mechanisms effectively enhanced the detection precision and operation speed of the models by slightly enhancing parameters. Optimal models among the three types of models were selected for comparison, and results showed that Faster R-CNN+SE had lower detection precision, YOLOx+ECA required the least parameters with the highest detection precision, and SSD+SE showed optimal real-time performance with relatively high detection precision. This study solved the problem of difficulty in grape leaf disease detection and provided a reference for the analysis of grape diseases and symptoms in automated agricultural production. based on attention mechanisms.
The SED Machine: A Spectrograph to Efficiently Classify Transient Events Discovered by PTF

Abstract The Palomar Transient Factory (PTF) is a project aimed to discover transients in the Universe, including Type Ia supernovae, core-collapse supernovae, and other exotic and rare transient events. PTF utilizes the Palomar 48-inch Telescope (P48) for discovering the transients, and follow-up mainly by the Palomar 60-inch Telescope (P60, for photometric light and color curves), as well as other telescopes. The discovery rate of PTF is about 7000 candidate transients per year, but currently only about 10% of the candidates are being followed-up and classified. To overcome this shortcoming, a dedicated spectrograph, called the SED Machine, is being designed and built at the California Institute of Technology for the P60 Telescope, aiming to maximize the classification efficiency of transients discovered by PTF. The SED Machine is a low resolution (R ~ 100) IFU spectrograph. It consists of a rainbow camera for spectrophotometric calibration, and a lenslet array plus 3-prism optics system for integrated field spectra. An overview of the science and design of the SED Machine is presented here.
Transit communication via Twitter during the COVID-19 pandemic

Transit providers have used social media (e.g., Twitter) as a powerful platform to shape public perception and provide essential information, especially during times of disruption and disaster. This work examines how transit agencies used Twitter during the COVID-19 pandemic to communicate with riders and how the content and general activity influence rider interaction and Twitter handle popularity. We analyzed 654,345 tweets generated by the top 40 transit agencies in the US, based on Vehicles Operated in Annual Maximum Service (VOM), from January 2020 to August 2021. We developed an analysis framework, using advanced machine learning and natural language processing models, to understand how agencies’ tweeting patterns are associated with rider interaction outcomes during the pandemic. From the transit agency perspective, we find smaller agencies tend to generate a higher percentage of COVID-related tweets and some agencies are more repetitive than their peers. Six topics (i.e., face covering, essential service appreciation, free resources, social distancing, cleaning, and service updates) were identified in the COVID-related tweets. From the followers’ interaction perspective, most agencies gained followers after the start of the pandemic (i.e., March 2020). The percentage of follower gains is positively correlated with the percentage of COVID-related tweets, tweets replying to followers, and tweets using outlinks. The average like counts per COVID-related tweet is positively correlated with the percentage of COVID-related tweets and negatively correlated with the percentage of tweets discussing social distancing and agency repetitiveness. This work can inform transportation planners and transit agencies on how to use Twitter to effectively communicate with riders to improve public perception of health and safety as it relates to transit ridership during delays and long-term disruptions such as those created by the COVID-19 public health crisis.
THE KEPLER PIXEL RESPONSE FUNCTION

Kepler seeks to detect sequences of transits of Earth-size exoplanets orbiting solar-like stars. Such transit signals are on the order of 100 ppm. The high photometric precision demanded by Kepler requires detailed knowledge of how the Kepler pixels respond to starlight during a nominal observation. This information is provided by the Kepler pixel response function (PRF), defined as the composite of Kepler's optical point-spread function, integrated spacecraft pointing jitter during a nominal cadence and other systematic effects. To provide sub-pixel resolution, the PRF is represented as a piecewise-continuous polynomial on a sub-pixel mesh. This continuous representation allows the prediction of a star's flux value on any pixel given the star's pixel position. The advantages and difficulties of this polynomial representation are discussed, including characterization of spatial variation in the PRF and the smoothing of discontinuities between sub-pixel polynomial patches. On-orbit super-resolution measurements of the PRF across the Kepler field of view are described. Two uses of the PRF are presented: the selection of pixels for each star that maximizes the photometric signal-to-noise ratio for that star, and PRF-fitted centroids which provide robust and accurate stellar positions on the CCD, primarily used for attitude and plate scale tracking. Good knowledge of the PRF has been a critical component for the successful collection of high-precision photometry by Kepler.
X-ray afterglow of GRB 050712: multiple energy injections into the external shock

As indicated by observed X-ray flares, a great amount of energy can be intermittently released from the postburst central engine of gamma-ray bursts (GRBs). As a natural consequence, the GRB's external shock could be repeatedly energized. With such a multiple energy injection model, we explore the unique X-ray afterglow light curve of GRB 050712, which exhibits four shallow decay plateaus. Together with three early X-ray flares, the central engine of GRB 050712 is believed to have released energy at least seven times after the burst. Furthermore, we find that the energies released during the four plateaus are all on the same order of magnitude, but the luminosity significantly decreased with time. These results may provide some interesting implications for the GRB central engine.
Magnetised Accretion Discs in Kerr Spacetimes II: Hot Spots

Context. Quasi-periodic variability has been observed in a number of X-ray binaries harboring black hole candidates. In general relativity, black holes are uniquely described by the Kerr metric and, according to the cosmic censorship conjecture, curvature singularities always have to be clothed by an event horizon. Aims. In this paper, we study the effect of an external magnetic field on the observed light curves of orbiting hot spots in thin accretion discs around Kerr black holes and naked singularities. Methods. We employ a ray-tracing algorithm to calculate the light curves and power spectra of such hot spots as seen by a distant observer for uniform and dipolar magnetic field configurations assuming a weak coupling between the magnetic field and the disc matter. Results. We show that the presence of an external dipolar magnetic field leads to potentially observable modifications of these signals for both Kerr black holes and naked singularities, while an external uniform magnetic field has practically no effect. In particular, we demonstrate that the emission from a hot spot orbiting near the innermost stable circular orbit of a naked singularity in a dipolar magnetic field can be significantly harder than the emission of the same hot spot in the absence of such a magnetic field. Conclusions. The comparison of our model with observational data may allow us study the geometry of magnetic fields around compact objects and to test the cosmic censorship conjecture in conjunction with other observables such as thermal continuum spectra and iron line profiles.
Impact of dataset on the study of crop disease image recognition

: Datasets are very important in image recognition research based on machine learning methods. In particular, advanced methods such as deep learning and transfer learning are more dependent on datasets used for training models. The quality of datasets directly affects the final effect of these methods. In the research of crop disease image recognition, due to the complication of the agricultural environment and the variety of crops, datasets are scarce at present. Therefore, more and more researches adopt methods based on transfer learning, which can make up for the lack of data in the target domain with the help of other datasets. Among these methods, the selection of auxiliary domain datasets has great impact on the modeling effect of target domain. In order to clarify the impact of datasets on the research of crop disease image recognition, this study used different deep neural network frameworks to study and compare the effects of different datasets in crop disease image recognition based on transfer learning. The selected datasets include PlantVillage and Image Database for Agricultural Diseases and Pests Research (IDADP), which have been widely used in recent studies. And the selected deep neural network frameworks include ResNet50, InceptionV3, and EfficientNet. In the method of this study, the datasets are preprocessed first, such as data enhancement. After dividing the auxiliary domain and the target domain, the selected deep neural network frameworks are used to pre-train the model on the auxiliary domain dataset. Finally, the parameter-based transfer learning method was used to construct the corresponding crop disease recognition model in the target. In the experiments, multiple different datasets and different models were tested and compared. The results show that when the test set samples and training sample scenarios are consistent, the recognition accuracy of different network frameworks on multiple test sets is generally high. When the scenarios of test set samples and training samples are inconsistent, the recognition of various test sets by different network models cannot obtain ideal results. For the recognition of crop disease images that are collected from the actual cultivation environment, the use of IDADP dataset modeling is better, and it has more practical value in the actual application of crop disease image recognition.
Relativistic Non-Thermal Bremsstrahlung Radiation

By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution N(p)dp = k p-qdp. We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.
Effect of intergalactic medium on the observability of Lyα emitters during cosmic reionization

We perform a systematic study of how the inhomogeneities in the intergalactic medium (IGM) affect the observability of Lyα emitters (LAEs) around the epoch of reionization. We focus on the IGM close to the galaxies as the detailed ionization distribution and velocity fields of this region could significantly influence the scattering of Lyα photons off neutral H atoms as they traverse the IGM after escaping from the galaxy. We simulate the surface brightness (SB) maps and spectra of more than 100 LAEs at z = 7.7 as seen by an observer at z = 0. To achieve this, we extract the source properties of galaxies and their surrounding IGM from cosmological simulations of box sizes 5–30 h−1 Mpc and then follow the coupled radiative transfer of ionizing and Lyα radiation through the IGM using crashα. We find that the simulated SB profiles are extended and their detailed structure is affected by inhomogeneities in the IGM, especially at high neutral fractions. The detectability of LAEs and the fraction of the flux observed depend heavily on the shape of the SB profile and the SB threshold (SB th) of the observational campaign. Only ultradeep observations (e.g. erg s−1 cm−2 arcsec−2) would be able to obtain the true underlying mass–luminosity relation and luminosity functions of LAEs. The details of our results depend on whether Lyα photons are significantly shifted in the galaxy to longer wavelengths, the mean ionization fraction in the IGM and the clustering of ionizing sources. These effects can lead to an easier escape of Lyα photons with less scattering in the IGM and a concentrated SB profile, similar to the one of a point source. Finally, we show that the SB profiles are steeper at high-ionization fraction for the same LAE sample which can potentially be observed from the stacked profile of a large number of LAEs.
Global strong solution to the density-dependent incompressible flow of liquid crystals

The initial-boundary value problem for the density-dependent incompressible flow of liquid crystals is studied in a three-dimensional bounded smooth domain. For the initial density away from vacuum, the existence and uniqueness is established for both the local strong solution with large initial data and the global strong solution with small data. It is also proved that when the strong solution exists, a weak solution with the same data must be equal to the unique strong solution.
Terahertz-visible two-photon rotational spectroscopy of cold OD −

We present a method to measure rotational transitions of molecular anions in the terahertz domain by sequential two-photon absorption. Ion excitation by bound-bound terahertz absorption is probed by absorption in the visible on a bound-free transition. The visible frequency is tuned to a state-selective photodetachment transition of the excited anions. This provides a terahertz action spectrum for just a few hundred molecular ions. To demonstrate this we measure the two lowest rotational transitions, $J=1\ensuremath{\leftarrow}0$ and $J=2\ensuremath{\leftarrow}1$ of ${\mathrm{OD}}^{\ensuremath{-}}$ anions in a cryogenic 22-pole trap. We obtain rotational transition frequencies of 598 596.08(19) MHz for $J=1\ensuremath{\leftarrow}0$ and 1 196 791.57(27) MHz for $J=2\ensuremath{\leftarrow}1$ of ${\mathrm{OD}}^{\ensuremath{-}}$, in good agreement with their only previous measurement. This two-photon scheme opens up terahertz rovibrational spectroscopy for a range of molecular anions, in particular for polyatomic and cluster anions.
MHV Lagrangians for Yang--Mills and QCD

Over the past few decades, it has been realised that gauge theory scattering amplitudes have structures much simpler than the traditional Feynman graph driven approach would suggest. In particular, Parke and Taylor found a particularly simple expression for the tree-level amplitudes with two gluons of different helicity than the others (the so-called MHV amplitudes). Cachazo, Svrcek and Witten (CSW) devised rules for constructing tree-level amplitudes by sewing lower-valence MHV amplitudes together with scalar propagators. It was shown by Mansfield in 2005 that a canonical change of the field variables could be constructed that resulted in a lagrangian whose vertices were proportional to MHV amplitudes, continued off-shell by CSW's prescription, the so-called Canonical MHV Lagrangian. We derive the explicit form of this transformation and use this to show that the vertices are indeed the Parke--Taylor amplitudes for up to five gluons. Noting that CSW's MHV rules cannot be used to construct the tree-level (-++) or one-loop (++++) amplitudes, we extend our work to augment the MHV rules with so-called completion vertices. These permit construction of these missing amplitudes by means of evasion of the S-matrix equivalence theorem. Indeed, together they reconstruct off-shell light-cone Yang-Mills amplitudes algebraically. We also give a prescription for dimensional regularisation of the Canonical MHV Lagrangian. Finally, we construct a canonical MHV lagrangian with massless fermions in the fundamental representation using a similar methodology.