Miracle-dz/UniFAR-FTUs huggingface dataset:
Casimir forces and quantum friction of finite-size atoms in relativistic trajectories

We study quantum friction and Casimir forces with a full-relativistic formalism for atoms modelled as Unruh-DeWitt detectors in the presence of arbitrary macroscopic objects. We consider the general case of atoms with arbitrary relativistic trajectories in arbitrary quantum states (including coherent superpositions) close to objects that impose arbitrary boundary conditions. Particularizing for conducting plates, we show that, for relative velocities close to the speed of light, the quantum friction diverges while the Casimir force is almost independent of the velocity. Since we include the effect of the finite size of the detector and the finite interaction time, we also obtain quantum friction when the detector is isolated but follows a non-inertial trajectory.
Characterizing Optical Variability of OJ 287 in 2016–2017

We report on a recent multiband optical photometric and polarimetric observational campaign of the blazar OJ 287 that was carried out during 2016 September–2017 December. We employed nine telescopes in Bulgaria, China, Georgia, Japan, Serbia, Spain, and the United States. We collected over 1800 photometric image frames in BVRI bands and over 100 polarimetric measurements over ∼175 nights. In 11 nights with many quasi-simultaneous multiband (V, R, I) observations, we did not detect any genuine intraday variability in flux or color. On longer timescales, multiple flaring events were seen. Large changes in color with respect to time and in a color–magnitude diagram were seen, and while only a weak systematic variability trend was noticed in color with respect to time, the color–magnitude diagram shows a bluer-when-brighter trend. Large changes in the degree of polarization and substantial swings in the polarization angle were detected. The fractional Stokes parameters of the polarization showed a systematic trend with time in the beginning of these observations, followed by chaotic changes and then an apparently systematic variation at the end. These polarization changes coincide with the detection and duration of the source at very high energies as seen by VERITAS. The spectral index shows a systematic variation with time and V-band magnitude. We briefly discuss possible physical mechanisms that could explain the observed flux, color, polarization, and spectral variability.
Designs, graphs, codes, and their links

From the Publisher: Although design theory, graph theory and coding theory, had their origins in various areas of applied mathematics, today they are found under the umbrella of discrete mathematics. Here the authors have considerably reworked and expanded their earlier successful books on designs, graphs and codes, into an invaluable textbook. They do not seek to consider each of these three topics individually, but rather to stress the many and varied connections between them. The discrete mathematics needed is developed in the text, making this book accessible to any student with a background of undergraduate algebra. Many exercises and useful hints are included throughout, and a large number of references are given.
Discovery of Extended Main-sequence Turnoffs in Four Young Massive Clusters in the Magellanic Clouds

An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color–magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet–visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35–50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.
The Pearson random walk

The Pearson random walk consists of a sequence of straight lines each at a random angle with respect to the preceding one. This article reviews some of the techniques available for approximating the probability density function for the end‐to d distances and the projection on a given axis. When there is a known upper bound on the maximum extension (i.e., the sum of the step lengths) one can write a Fourier series for the density function whose rate of convergence increases with increasing number of steps. When the step sizes are not too disparate use of the method of steepest descents leads to an approximation that is good to 0(1/n) (where n is the number of steps) over the entire range. In addition we develop a method for approximating the behavior of the density functions in the neighborhood of maximum extension. In 2‐D this leads to an asymptotic series, derived by the use of a Tauberian theorem. In 3‐D the technique leads to the generalization of an exact solution derived by Rayleigh and Treloar. Fina.
Structural Basis for the Immunogenicity of the C-Terminus of VP1 of Echovirus 3 Revealed by the Binding of a Neutralizing Antibody

Echovirus 3 (E3), a serotype of human enterovirus B (HEV-B), causes severe diseases in infants. Here, we determined the structures of E3 with a monoclonal antibody (MAb) 6D10 by cryo-EM to comprehensively understand the specificities and the immunological characteristic of this serotype. The solved cryo-EM structures of the F-, A-, and E-particles of E3 bound with 6D10 revealed the structural features of the virus–antibody interface. Importantly, the structures of E-particles bound with 6D10 revealed for the first time the nature of the C-terminus of VP1 for HEV-Bs at the structural level. The highly immunogenic nature of this region in the E-particles provides new strategies for vaccine development for HEV-Bs.
An abundance analysis from the STIS-HST UV spectrum of the non-magnetic Bp star HR 6000

The sharp-line spectrum of the Bp star HR 6000 has peculiarities that distinguish it from those of the HgMn stars with which it is sometimes associated. The position of the star close to the center of the Lupus 3 molecular cloud, whose estimated age is on the order of 9.1 +/- 2.1 Myr, has lead to the hypothesis that the anomalous peculiarities of HR 6000 can be explained by the young age of the star. Observational material from HST provides the opportunity to extend the abundance analysis previously performed for the optical region and clarify the properties of this remarkable peculiar star. Our aim was to obtain the atmospheric abundances for all the elements observed in a broad region from 1250 to 10000 A. An LTE synthetic spectrum was compared with a high-resolution spectrum observed with STIS equipment in the 1250-3040 A interval. The adopted model is an ATLAS12 model already used for the abundance analysis of a high-resolution optical spectrum observed at ESO with UVES. The stellar parameters are Teff=13450K, logg=4.3, and zero microturbulent velocity. Abundances for 28 elements and 7 upper limits were derived from the ultraviolet spectrum. Adding results from previous work, we have now quantitative results for 37 elements, some of which show striking contrasts with those of a broad sample of HgMn stars. The analysis has pointed out ionization anomalies and line-to-line variation in the derived abundances, in particular for silicon. The inferred discrepancies could be explained by non-LTE effects and with the occurrence of diffusion and vertical abundance stratification. In the framework of the last hypothesis, we obtained, by means of trial and error, empirical step functions of abundance versus optical depth log(tau_5000) for carbon, silicon, manganese, and gold, while we failed to find such a function for phosphorous.
Bulk and surface electronic properties of SmB 6 : A hard x-ray photoelectron spectroscopy study

We have carried out bulk-sensitive hard x-ray photoelectron spectroscopy measurements on in situ cleaved and ex situ polished ${\mathrm{SmB}}_{6}$ single crystals. Using the multiplet structure in the Sm $3d$ core level spectra, we determined reliably that the valence of Sm in bulk ${\mathrm{SmB}}_{6}$ is close to 2.55 at $\ensuremath{\sim}5$ K. Temperature dependent measurements revealed that the Sm valence gradually increases to 2.64 at 300 K. From a detailed line shape analysis we can clearly observe that not only the $J=0$ but also the $J=1$ state of the Sm $4{f}^{6}$ configuration becomes occupied at elevated temperatures. Making use of the polarization dependence, we were able to identify and extract the Sm $4f$ spectral weight of the bulk material. Finally, we revealed that the oxidized or chemically damaged surface region of the ex situ polished ${\mathrm{SmB}}_{6}$ single crystal is surprisingly thin, about 1 nm only.
Street Art and the Reconfiguration of Civic Advocacy in Nairobi City

Abstract Over the last two decades, social protests in Kenya have shifted to using art. Social protests involving art, such as the ‘State-Burial-ballot-Revolution’ and ‘Occupy-Parliament Movement,’ among others, have been witnessed in the country in the recent past. These artistic productions interpellate the spaces they interact with – the street, parliament, buildings, perimeter fences and public arenas – to denounce various issues, such as corruption, extra-judicial killings, political greed and other social injustices afflicting the nation. Espousing concepts of the carnivalesque by Mikhail Bakhtin, this article analyzes street art – street theatre and graffiti – utilized in Nairobi’s streets. In examining the literary aesthetics embedded in these innovative creative works, this article shows the significant potential of street art to stake, reclaim and reconfigure civil advocacy and, in the process, spur civic participation in various issues affecting the country today.
Time‐variant linear optimal finite impulse response estimator for discrete state‐space models

A general p‐shift linear optimal finite impulse response (FIR) estimator is proposed for filtering (p = 0), p‐lag smoothing (p < 0), and p‐step prediction (p > 0) of discrete time‐varying state‐space models. An optimal solution is found in the batch form with the mean square initial state function self‐determined by solving the discrete algebraic Riccati equation. An unbiased batch solution is shown to be independent on noise and initial conditions. The mean square errors in both the optimal and unbiased estimates have been determined along with the noise power gain and estimate error bound. The following important inferences have been made on the basis of numerical simulation. Unlike the time‐invariant Kalman filter, the relevant optimal FIR one is very less sensitive to noise, especially when N ≫ 1. Both time varying, the optimal FIR and Kalman estimates trace along almost the same trajectories with similar errors and sensitivities to noise. Overall, the optimal FIR estimator demonstrates better robustness than the Kalman one against faults in the noise description. Copyright © 2011 John Wiley & Sons, Ltd.
Dietary Phenolic Compounds as Anticancer Natural Drugs: Recent Update on Molecular Mechanisms and Clinical Trials

Given the stochastic complexity of cancer diseases, the development of chemotherapeutic drugs is almost limited by problems of selectivity and side effects. Furthermore, an increasing number of protective approaches have been recently considered as the main way to limit these pathologies. Natural bioactive compounds, and particularly dietary phenolic compounds, showed major protective and therapeutic effects against different types of human cancers. Indeed, phenolic substances have functional groups that allow them to exert several anti-cancer mechanisms, such as the induction of apoptosis, autophagy, cell cycle arrest at different stages, and the inhibition of telomerase. In addition, in vivo studies show that these phenolic compounds also have anti-angiogenic effects via the inhibition of invasion and angiogenesis. Moreover, clinical studies have already highlighted certain phenolic compounds producing clinical effects alone, or in combination with drugs used in chemotherapy. In the present work, we present a major advance in research concerning the mechanisms of action of the different phenolic compounds that are contained in food medicinal plants, as well as evidence from the clinical trials that focus on them.
Circumstellar discs in the young σ Orionis cluster

We present new K- and L � -band imaging observations for members of the young (3‐5 Myr) σ Orionis cluster, obtained at the United Kingdom Infrared Telescope (UKIRT) with the UKIRT 1‐5 micron Imager Spectrometer (UIST). We determine (K − L � ) colour excesses with respect to the photospheres, finding evidence for warm circumstellar dust around 27 out of 83 cluster members that have masses between 0.04 and 1.0 M� . This indicates a circumstellar disc frequency of at least (33 ± 6) per cent for this cluster, consistent with previous determinations from smaller samples and also consistent with the 3-Myr disc half-life suggested by Haisch et al. There is marginal evidence that the disc frequency declines towards lower masses, but the data are also consistent with no mass dependence at all. There is no evidence for spatial segregation of objects with and without circumstellar discs.
LENS — the Low‐Energy Neutrino Spectrometer

Despite the recent successes of SNO and KamLAND, the only detectors sensitive to <1 MeV‐neutrinos have been the radiochemical chlorine and gallium solar neutrino experiments. LENS is being developed to measure in real time the charge‐current fluxes and energy spectra of the lowest energy solar neutrinos, from the pp and 7Be branches (91% and 7% of solar neutrinos). The detector medium will be a metal‐loaded liquid scintillator (M‐LS), with indium as the metal, which serves as the target for neutrino capture in the LS. 115In has 95.71% natural abundance and a 114.2‐keV neutrino‐capture Q‐value. Neutrino capture in 115In produces a β particle and preferentially feeds an excited state of 115Sn that de‐excites by delayed emission of two γ rays. This triple‐coincidence “tag” in time and space in principle is a very powerful tool to discriminate neutrino‐capture events from backgrounds. The International LENS R&D Collaboration is working to develop an In‐LS neutrino detector, with special properties, such as hi.
The Glycosyltransferase Pathway: An Integrated Analysis of the Cell Metabolome

Nucleotide sugar-dependent glycosyltransferases (UGTs) are critical to the homeostasis of endogenous metabolites and the detoxification of xenobiotics. Their impact on the cell metabolome remains unknown. Cellular metabolic changes resulting from human UGT expression were profiled by untargeted metabolomics. The abundant UGT1A1 and UGT2B7 were studied as UGT prototypes along with their alternative (alt.) splicing-derived isoforms displaying structural differences. Nineteen biochemical routes were modified, beyond known UGT substrates. Significant variations in glycolysis and pyrimidine pathways, and precursors of the co-substrate UDP-glucuronic acid were observed. Bioactive lipids such as arachidonic acid and endocannabinoids were highly enriched by up to 13.3-fold (p < 0.01) in cells expressing the canonical enzymes. Alt. UGT2B7 induced drastic and unique metabolic perturbations, including higher glucose (18-fold) levels and tricarboxylic acid cycle (TCA) cycle metabolites and abrogated the effects of the UGT2B7 canonical enzyme when co-expressed. UGT1A1 proteins promoted the accumulation of branched-chain amino acids (BCAA) and TCA metabolites upstream of the mitochondrial oxoglutarate dehydrogenase complex (OGDC). Alt. UGT1A1 exacerbated these changes, likely through its interaction with the OGDC component oxoglutarate dehydrogenase-like (OGDHL). This study expands the breadth of biochemical pathways associated with UGT expression and establishes extensive connectivity between UGT enzymes, alt. proteins and other metabolic processes.
Nutritional Programming: History, Hypotheses, and the Role of Prenatal Factors in the Prevention of Metabolic Diseases—A Narrative Review

Childhood obesity and the numerous lifestyle diseases associated with it are undoubtedly among the key problems in modern medicine and public health. However, this problem concerns not only the present or immediate future, but also the longer term. Adult health is fundamentally shaped in the first years of life and in the fetal period. The preconceptual period, which is responsible for the proper preparation of the internal environment for the life and development of the fetus during pregnancy, is also significant. A special role in describing the phenomenon of conditioning the metabolism of the new human being is now attributed to the theory of nutritional programming. Research in this area was pioneered by David Barker, who put forward the theory of the “stunted phenotype” and described the relationship between a child’s birth weight, which is largely a consequence of the mother’s feeding behaviour, and diseases such as ischaemic heart disease, type 2 diabetes (T2D), dyslipidemia, or high blood pressure. This narrative review aims to provide an overview of the history, theory, and prenatal mechanisms involved in nutritional programming and its relationship to childhood obesity and other metabolic diseases.
Plasmons in bias-induced topological phase transition in black phosphorus

We investigate the plasmons in bilayer black phosphorus (BP) with bias-driven formation of Dirac cones, by developing an effective two-band Hamiltonian that captures this electronic transition with great accuracy. We show that the appearance of the Dirac cones lead to additional linearly dispersing acoustic plasmon mode, in conjunction to the conventional plasmon. In addition, the change in the Fermi surface topology from a disc to ring or dual pockets also modifies the dielectric loss.
Does the website credibility of online travel agencies (OTAs) affect customers’ evaluation and future intentions?

ABSTRACT In an uncertain and escalating risk period resulting from the prolonged pandemic crisis, this study aimed to identify the dimensional nature of online travel agencies’ (OTAs) website credibility, and empirically investigate the effects of its components on attitude and behavioral intentions. This study was conducted by collecting 559 questionnaires from mainland Chinese OTA users in the middle of the COVID-19 pandemic. The data analyses showed that OTA website credibility comprised six components. Other proposed paths, with the exception of four, were significant at the . 05 or . 001 level. Interestingly, the paths between content credibility and attitude toward the OTA and between content credibility and loyalty to the OTA were not significant. However, overall, it was confirmed that OTA website credibility determined attitude toward the OTA and loyalty to the OTA, which led to behavioral intention.
A note on the estimation of the skew normal and the skew exponential power distributions

The present paper proposes a version of the minimum chi-square method and an asymptotically equivalent maximum likelihood method to handle the estimation of the parameters of the Skew Normal model and the Skew Exponential Power model in small samples. In a comparison with the standard maximum likelihood estimators, the proposed methods substantially reduce the frequency of unsatisfactory estimates of the skewness parameter.
Punks and profiteers in the war on death

The genre of transhumanism known as biohacking, or the human augmentation movement, is rooted in a history of medical and scientific developments in the service of religious nationalism, where the perfection of the American body is advanced as a patriotic duty and symbol of the superiority of the American nation. Some participants in the biohacking scene advocate for a classic global rehabilitation project in the tradition of UNESCO, a post-war project of global salvation through collective evolution and science literacy. This vision contrasts sharply with separatist and grassroots biohacking projects. I introduce a model of ‘punks and profiteers’ to investigate two broad genres of biohacking: Corporate Medical Futurism and the DIY biohacker movement. Both strands rely on the fruits of the post-WWII boom in prosthetics, plastic surgery, and drug therapies, fruits well watered by religious and nationalist imperatives. Exploring the war on death led me to the grinder punk biohacking movement, which troubles the dominant view on transhumanism with their delight in human existence, taking limited interest in, or even demonstrating hostility toward, immortality, and rejecting ideas of finding salvation in escape from nature, the human body, and the earth.
Supernova constraints on spatial variations of the vacuum energy density

We consider a very simple toy model for a spatially varying `cosmological constant', where we are inside a spherical bubble (with a given set of cosmological parameters) that is surrounded by a larger region where these parameters are different. This model includes essential features of more realistic scenarios with a minimum number of parameters. We calculate the luminosity distance in the presence of spatial variations of the vacuum energy density using linear perturbation theory and discuss the use of type Ia supernovae to impose constraints on this type of models. We find that presently available observations are only constraining at very low redshifts, but also provide independent confirmation that the high red-shift supernovae data does prefer a relatively large positive cosmological constant.
Application of Semantic Analysis and LSTM-GRU in Developing a Personalized Course Recommendation System

The selection of elective courses based on an individual’s domain interest is a challenging and critical activity for students at the start of their curriculum. Effective and proper recommendation may result in building a strong expertise in the domain of interest, which in turn improves the outcomes of the students getting better placements, and enrolling into higher studies of their interest, etc. In this paper, an effective course recommendation system is proposed to help the students in facilitating proper course selection based on an individual’s domain interest. To achieve this, the core courses in the curriculum are mapped with the predefined domain suggested by the domain experts. These core course contents mapped with the domain are trained semantically using deep learning models to classify the elective courses into domains, and the same are recommended based on the student’s domain expertise. The recommendation is validated by analyzing the number of elective course credits completed and the grades scored by a student who utilized the elective course recommendation system, with the grades scored by the student who was subjected to the assessment without elective course recommendations. It was also observed that after the recommendation, the students have registered for a greater number of credits for elective courses on their domain of expertise, which in-turn enables them to have a better learning experience and improved course completion probability.