Miracle-dz/UniFAR-FTUs huggingface dataset:
Human detection and tracking in surveillance videos

The thesis addresses the following challenging problems of detecting and tracking humans in the presence of occlusions in typical surveillance videos: (1) adaptation of semantic-part-based human detectors to new surveillance video sequence when trained detectors using other video data not performing well on the new video data; (2) tracking of humans with person identification minimizing identification errors over longer tracking periods; and (3) hierarchical spatial and temporal analysis for discriminative tracking of human targets. The thesis aims to improve the stateof-the-art performance in human detection and tracking by studying the human detectors, extended tracking of track segments (tracklets) generated from short term tracking of detection responses. For the adaptation of semantic-part-based human detectors to new surveillance video sequence, a unified deep CNN model for joint learning of features, semantic pedestrian part detectors and a transfer learning model is developed. The components within this deep CNN model interact with each other in the learning process, which facilitates the optimization of the learned components during the co-operative learning. In particular, an adaptation layer is proposed to embed the capability of knowledge transfer into the CNN model. As a result, the proposed transferred CNN (T-CNN) model is able to transfer the visual knowledge of the semantic pedestrian parts from the source data to target data. Extensive experimental evaluations show that the proposed method is better than other deep learning based methods in terms of detection performance. Moreover, the adaptive deep features can be complementary to the pre-defined features used by other state-of-the-art methods. For tracking of humans with person identification minimizing identification errors over longer tracking periods, a novel method, based on online target-specific
How to quench a galaxy

We show how the interplay between active galactic nuclei (AGNs) and merger history determines whether a galaxy quenches star formation (SF) at high redshift. We first simulate, in a full cosmological context, a galaxy of total dynamical mass Mvir = 1012 M⊙ at z = 2. Then we systematically alter the accretion history of the galaxy by minimally changing the linear overdensity in the initial conditions. This ‘genetic modification’ approach allows the generation of three sets of Λ CDM initial conditions leading to maximum merger ratios of 1:10, 1:5 and 2:3, respectively. The changes leave the final halo mass, large-scale structure and local environment unchanged, providing a controlled numerical experiment. Interaction between the AGN physics and mergers in the three cases leads, respectively, to a star-forming, temporarily quenched and permanently quenched galaxy. However, the differences do not primarily lie in the black hole accretion rates, but in the kinetic effects of the merger: the galaxy is resilient against AGN feedback unless its gaseous disc is first disrupted. Typical accretion rates are comparable in the three cases, falling below 0.1 M⊙ yr−1, equivalent to around 2 per cent of the Eddington rate or 10−3 times the pre-quenching star formation rate, in agreement with observations. This low level of black hole accretion can be sustained even when there is insufficient dense cold gas for SF. Conversely, supernova feedback is too distributed to generate outflows in high-mass systems, and cannot maintain quenching over periods longer than the halo gas cooling time.
A new route towards merging massive black holes

Recent advances in gravitational-wave astronomy make the direct detection of gravitational waves from the merger of two stellar-mass compact objects a realistic prospect. Evolutionary scenarios towards mergers of double compact objects generally invoke common-envelope evolution which is poorly understood, leading to large uncertainties in merger rates. We explore the alternative scenario of massive overcontact binary (MOB) evolution, which involves two very massive stars in a very tight binary which remain fully mixed due to their tidally induced high spin. We use the public stellar-evolution code MESA to systematically study this channel by means of detailed simulations. We find that, at low metallicity, MOBs produce double-black-hole (BH+BH) systems that will merge within a Hubble time with mass ratios close to one, in two mass ranges, ~25.60msun and >~ 130msun, with pair instability supernovae (PISNe) being produced in-between. Our models are also able to reproduce counterparts of various stages in the MOB scenario in the local Universe, providing direct support for it. We map the initial parameter space that produces BH+BH mergers, determine the expected chirp mass distribution, merger times, Kerr parameters and predict event rates. We typically find that for Z~<Z_sun/10, there is one BH+BH merger for ~1000 core-collapse supernovae. The advanced LIGO (aLIGO) detection rate is more uncertain and depends on the metallicity evolution. Deriving upper and lower limits from a local and a global approximation for the metallicity distribution of massive stars, we estimate aLIGO detection rates (at design limit) of ~19-550 yr^(-1) for BH+BH mergers below the PISN gap and of ~2.1-370 yr^(-1) above the PISN gap. Even with conservative assumptions, we find that aLIGO should soon detect BH+BH mergers from the MOB scenario and that these could be the dominant source for aLIGO detections.
Exact thermodynamic Casimir forces for an interacting three-dimensional model system in film geometry with free surfaces

The limit n → ∞ of the classical O(n) ϕ4 model on a 3d film with free surfaces is studied. Its exact solution involves a self-consistent 1d Schrödinger equation, which is solved numerically for a partially discretized as well as for a fully discrete lattice model. Extremely precise results are obtained for the scaled Casimir force at all temperatures. Obtained via a single framework, they exhibit all relevant qualitative features of the thermodynamic Casimir force known from wetting experiments on 4He and Monte Carlo simulations, including a pronounced minimum below the bulk critical point.
Transitions near the onset of low Prandtl-number rotating magnetoconvection

We investigate the onset of convective instability and subsequent transitions near it in Rayleigh-Benard convection (RBC) of electrically conducting low Prandtl-number (Pr) fluids in the simultaneous presence of rotation about the vertical axis and external uniform horizontal magnetic field with free-slip boundary conditions. Both three dimensional direct numerical simulations (DNS) and low dimensional modeling of the system have been performed for the investigation. DNS results show a plethora of patterns near the onset of convection for weak magnetic field. Most interestingly, the Nusselt number (Nu) computed from the DNS data for relatively stronger magnetic field shows a sharp jump at the onset, indicating substantial enhancement of the convective heat transfer. The origin of these flow patterns, as well as the reason for a notable increase of heat transfer near the onset of convection, are then explained using low dimensional models constructed from DNS data.
Progenitors of low-luminosity Type II-Plateau supernovae

The progenitors of low-luminosity Type II-Plateau supernovae (SNe II-P) are believed to be red supergiant (RSG) stars, but there is much disparity in the literature concerning their mass at core collapse and therefore on the main sequence. Here, we model the SN radiation arising from the low-energy explosion of RSG stars of 12, 25 and 27 M_⊙ on the main sequence and formed through single star evolution. Despite the narrow range in ejecta kinetic energy (2.5–4.2 × 10^50 erg) in our model set, the SN observables from our three models are significantly distinct, reflecting the differences in progenitor structure (e.g. surface radius, H-rich envelope mass and He-core mass). Our higher mass RSG stars give rise to Type II SNe that tend to have bluer colours at early times, a shorter photospheric phase, and a faster declining V-band light curve (LC) more typical of Type II-linear SNe, in conflict with the LC plateau observed for low-luminosity SNe II. The complete fallback of the CO core in the low-energy explosions of our high-mass RSG stars prevents the ejection of any ^56Ni (nor any core O or Si), in contrast to low-luminosity SNe II-P, which eject at least 0.001 M_⊙ of ^56Ni. In contrast to observations, Type II SN models from higher mass RSGs tend to show an H α absorption that remains broad at late times (due to a larger velocity at the base of the H-rich envelope). In agreement with the analyses of pre-explosion photometry, we conclude that low-luminosity SNe II-P likely arise from low-mass rather than high-mass RSG stars.
A WISE-based search for debris discs amongst M-dwarfs in nearby, young, moving groups

We present a search for debris discs amongst M-dwarf members of nearby, young (5-150 Myr) moving groups (MGs) using infrared (IR) photometry, primarily from the Wide Infrared Survey Explorer (WISE). A catalogue of 100 MG M-dwarfs that have suitable WISE data is compiled and 19 of these are found to have significant IR excess emission at 22$\mu$m. Our search is likely to be complete for discs where the ratio of flux from the disc to flux from the star $f_{\rm d}/f_{*} > 10^{-3}$. The spectral energy distributions are supplemented with 2MASS photometry and data at longer wavelengths and fitted with simple disc models to characterise the IR excesses. There is a bimodal distribution -- twelve targets have $W1-W4 > 3$, corresponding to $f_{\rm d}/f_{*} > 0.02$ and are likely to be gas-rich, primordial discs. The remaining seven targets have $W1-W4 < 1$ ($f_{\rm d}/f_{*} \lesssim 10^{-3}$) and include three objects with previously known or suspected debris discs and four new debris disc candidates that are all members of the Beta Pic MG. All of the IR excesses are identified in stars that are likely members of MGs with age $< 30$ Myr. The detected debris disc frequency falls from 13 to 5 per cent to $< 7$ per cent (at 95 per cent confidence) for objects younger or older than 30 Myr respectively. This provides evidence for the evolution of debris discs on this timescale and does not support models where the maximum of debris disc emission occurs much later in lower-mass stars.
Physically significant nonlocal nonlinear Schrödinger equation and its soliton solutions

A new integrable nonlocal nonlinear Schroedinger (NLS) equation with clear physical motivations is proposed. This equation is obtained from a special reduction of the Manakov system, and it describes Manakov solutions whose two components are related by a parity symmetry. Since the Manakov system governs wave propagation in a wide variety of physical systems, this new nonlocal equation has clear physical meanings. Solitons and multi-solitons in this nonlocal equation are also investigated in the framework of Riemann-Hilbert formulations. Surprisingly, symmetry relations of discrete scattering data for this equation are found to be very complicated, where constraints between eigenvectors in the scattering data depend on the number and locations of the underlying discrete eigenvalues in a very complex manner. As a consequence, general $N$-solitons are difficult to obtain in the Riemann-Hilbert framework. However, one- and two-solitons are derived, and their dynamics investigated. It is found that two-solitons are generally not a nonlinear superposition of one-solitons, and they exhibit interesting dynamics such as meandering and sudden position shifts. As a generalization, other integrable and physically meaningful nonlocal equations are also proposed, which include NLS equations of reverse-time and reverse-space-time types as well as nonlocal Manakov equations of reverse-space, reverse-time and reverse-space-time types.
Reconstructing the gravitational field of the local universe

Tests of gravity at the galaxy scale are in their infancy. As a first step to systematically uncovering the gravitational significance of galaxies, we map three fundamental gravitational variables – the Newtonian potential, acceleration and curvature – over the galaxy environments of the local universe to a distance of approximately 200 Mpc. Our method combines the contributions from galaxies in an all-sky redshift survey, halos from an N-body simulation hosting low-luminosity objects, and linear and quasi-linear modes of the density field. We use the ranges of these variables to determine the extent to which galaxies expand the scope of generic tests of gravity and are capable of constraining specific classes of model for which they have special significance. Finally, we investigate the improvements afforded by upcoming galaxy surveys.
Nuclear proton and neutron distributions in the detection of weak interacting massive particles

In the evaluation of weak interacting massive particles (WIMPs) detection rates, the WIMP-nucleus cross section is commonly described by using form factors extracted from charge distributions. In this work, we use different proton and neutron distributions taken from Hartree-Fock calculations. We study the effects of this choice on the total detection rates for six nuclei having different neutron excess, and taken from different regions of the nuclear chart. The use of different distributions for protons and neutrons becomes more important if isospin-dependent WIMP-nucleon interactions are considered. The need for distinct descriptions of proton and neutron densities decreases with the lowering of detection energy thresholds.
THE EVOLUTION OF BLACK HOLE SCALING RELATIONS IN GALAXY MERGERS

We study the evolution of black holes (BHs) on the MBH–σ and MBH–Mbulge planes as a function of time in disk galaxies undergoing mergers. We begin the simulations with the progenitor BH masses being initially below (Δlog MBH,i ∼ −2), on (Δlog MBH,i ∼ 0), and above (Δlog MBH,i ∼ 0.5) the observed local relations. The final relations are rapidly established after the final coalescence of the galaxies and their BHs. Progenitors with low initial gas fractions (fgas = 0.2) starting below the relations evolve onto the relations (Δlog MBH,f ∼ −0.18), progenitors on the relations stay there (Δlog MBH,f ∼ 0), and finally progenitors above the relations evolve toward the relations, but still remain above them (Δlog MBH,f ∼ 0.35). Mergers in which the progenitors have high initial gas fractions (fgas = 0.8) evolve above the relations in all cases (Δlog MBH,f ∼ 0.5). We find that the initial gas fraction is the prime source of scatter in the observed relations, dominating over the scatter arising from the evolutionary stage of the merger remnants. The fact that BHs starting above the relations do not evolve onto the relations indicates that our simulations rule out the scenario in which overmassive BHs evolve onto the relations through gas-rich mergers. By implication our simulations thus disfavor the picture in which supermassive BHs develop significantly before their parent bulges.
KECK-I MOSFIRE SPECTROSCOPY OF COMPACT STAR-FORMING GALAXIES AT z ≳ 2: HIGH VELOCITY DISPERSIONS IN PROGENITORS OF COMPACT QUIESCENT GALAXIES

We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift 2 ⩽ z ⩽ 2.5 with star formation rates of SFR ∼ 100 M☉ yr−1 and masses of log(M/M☉) ∼10.8. Their high integrated gas velocity dispersions of σint km s−1, as measured from emission lines of Hα and [O iii], and the resultant M⋆–σint relation and M⋆–Mdyn all match well to those of compact quiescent galaxies at z ∼ 2, as measured from stellar absorption lines. Since log(M⋆/Mdyn) =−0.06 ± 0.2 dex, these compact SFGs appear to be dynamically relaxed and evolved, i.e., depleted in gas and dark matter (<13%), and present larger σint than their non-compact SFG counterparts at the same epoch. Without infusion of external gas, depletion timescales are short, less than ∼300 Myr. This discovery adds another link to our new dynamical chain of evidence that compact SFGs at z ≳ 2 are already losing gas to become the immediate progenitors of compact quiescent galaxies by z ∼ 2.
Chasing Stars: The Myth of Talent and the Portability of Performance

It is taken for granted in the knowledge economy that companies must employ the most talented performers to compete and succeed. Many firms try to buy stars by luring them away from competitors. But Boris Groysberg shows what an uncertain and disastrous practice this can be. After examining the careers of more than a thousand star analysts at Wall Street investment banks, and conducting more than two hundred frank interviews, Groysberg comes to a striking conclusion: star analysts who change firms suffer an immediate and lasting decline in performance. Their earlier excellence appears to have depended heavily on their former firms' general and proprietary resources, organizational cultures, networks, and colleagues. There are a few exceptions, such as stars who move with their teams and stars who switch to better firms. Female stars also perform better after changing jobs than their male counterparts do. But most stars who switch firms turn out to be meteors, quickly losing luster in their new settings. Groysberg also explores how some Wall Street research departments are successfully growing, retaining, and deploying their own stars. Finally, the book examines how its findings apply to many other occupations, from general managers to football players. Chasing Stars offers profound insights into the fundamental nature of outstanding performance. It also offers practical guidance to individuals on how to manage their careers strategically, and to companies on how to identify, develop, and keep talent.
PHOTOMETRIC AND SPECTRAL SIGNATURES OF THREE-DIMENSIONAL MODELS OF TRANSITING GIANT EXOPLANETS

Using a three-dimensional general circulation model, we create dynamical model atmospheres of a representative transiting giant exoplanet, HD 209458b. We post-process these atmospheres with an opacity code to obtain transit radius spectra during the primary transit. Using a spectral atmosphere code, we integrate over the face of the planet seen by an observer at various orbital phases and calculate light curves as a function of wavelength and for different photometric bands. The products of this study are generic predictions for the phase variations of a zero-eccentricity giant planet's transit spectrum and of its light curves. We find that for these models the temporal variations in all quantities and the ingress/egress contrasts in the transit radii are small (<1.0%). Moreover, we determine that the day/night contrasts and phase shifts of the brightness peaks relative to the ephemeris are functions of photometric band. The J, H, and K bands are shifted most, while the IRAC bands are shifted least. Therefore, we verify that the magnitude of the downwind shift in the planetary “hot spot” due to equatorial winds is strongly wavelength dependent. The phase and wavelength dependence of light curves, as well as the associated day/night contrasts, can be used to constrain the circulation regime of irradiated giant planets and to probe different pressure levels of a hot Jupiter atmosphere. We posit that though our calculations focus on models of HD 209458b, similar calculations for other transiting hot Jupiters in low-eccentricity orbits should yield transit spectra and light curves of a similar character.
GRB 110328A/SWIFT J164449.3+573451: THE TIDAL OBLITERATION OF A DEEPLY PLUNGING STAR?

We examine the tidal disruption event (TDE) scenario to explain Sw 1644+57, a powerful and persistent X-ray source which suddenly became active as GRB 110328A. The precise localization at the center of a z = 0.35 galaxy argues for activity of the central engine as the underlying cause. We look at the suggestion by Bloom et al. of the possibility of a TDE. We argue that Sw 1644+57 cannot be explained by the traditional TDE model in which the periastron distance is close to the tidal disruption radius—three independent lines of argument indicate the orbit must be deeply plunging or else the powerful jet we are observing could not be produced. These arguments stem from (1) comparing the early X-ray light curve to the expected theoretical fallback rate, (2) looking at the time of transition to disk-dominated decay, and (3) considering the TDE rate. Due to the extreme excess in the tidal force above that which would be required minimally to disrupt the star in a deeply plunging orbit at periastron, we suggest this scenario might be referred to more descriptively as a tidal obliteration event (TOE) rather than a TDE.
CHANDRA OBSERVES THE END OF AN ERA IN SN 1987A

Updated imaging and photometric results from Chandra observations of SN 1987A, covering the last 16 years, are presented. We find that the 0.5–2 keV light curve has remained constant at ∼8 × 10−12 erg s−1 cm−2 since 9500 days, with the 3–8 keV light curve continuing to increase until at least 10,000 days. The expansion rate of the ring is found to be energy dependent, such that after day 6000 the ring expands faster in the 2–10 keV band than it does at energies <2 keV. Images show a reversal of the east–west asymmetry between 7000 and 8000 days after the explosion. The latest images suggest the southeastern side of the equatorial ring (ER) is beginning to fade. Consistent with the latest optical and infrared results, our Chandra analysis indicates the blast wave is now leaving the dense ER, which marks the beginning of a major change in the evolutionary phase of the supernova remnant 1987A.
Technique of Evaluating AS Importance Based on Preferred Route

Evaluating the importance of node is valuable for improving the network survivability.Due to the complexity of inter-domain policy,the existing evaluating methods which are based on static topology can not reflect the real importance of the autonomous systems(ASes) in routing.This paper is the first study to evaluate the AS importance through the best paths between the ASes from the view of dynamic routing.The more the best paths passing through an AS,the more important it is.An evaluation method based on preferred route is proposed,the complexity of which is O(l? nm) and the evaluated importance is more accurate.The time complexity is the same as the best complexity of the evaluating methods based on static topology.To verify the validity,the preferred route method is compared with two representative methods based on static topology under real routing data,which are degree method and stress centrality method respectively.The result shows that the preferred route method can discover the nodes of importance but small connections efficiently.Moreover,the evaluated importance is closer to the real AS importance than the other two methods.
Lattice Gauge Theory and the Origin of Mass

Most of the mass of everyday objects resides in atomic nuclei/ the total of the electrons' mass adds up to less than one part in a thousand. The nuclei are composed of nucleons---protons and neutrons---whose nuclear binding energy, though tremendous on a human scale, is small compared to their rest energy. The nucleons are, in turn, composites of massless gluons and nearly massless quarks. It is the energy of these confined objects, via $M=E/c^2$, that is responsible for everyday mass. This article discusses the physics of this mechanism and the role of lattice gauge theory in establishing its connection to quantum chromodynamics.