Miracle-dz/UniFAR-FTUs huggingface dataset:
Habitability around F-type stars

Abstract We explore the general astrobiological significance of F-type main-sequence stars with masses between 1.2 and 1.5 M⊙. Special consideration is given to stellar evolutionary aspects due to nuclear main-sequence evolution. DNA is taken as a proxy for carbon-based macromolecules following the paradigm that extraterrestrial biology may be most likely based on hydrocarbons. Consequently, the DNA action spectrum is utilized to represent the impact of the stellar ultraviolet (UV) radiation. Planetary atmospheric attenuation is taken into account based on parameterized attenuation functions. We found that the damage inflicted on DNA for planets at Earth-equivalent positions is between a factor of 2.5 and 7.1 higher than for solar-like stars, and there are intricate relations for the time-dependence of damage during stellar main-sequence evolution. If attenuation is considered, smaller factors of damage are obtained in alignment to the attenuation parameters. This work is motivated by earlier studies indicating that the UV environment of solar-type stars is one of the most decisive factors in determining the suitability of exosolar planets and exomoons for biological evolution and sustainability.
THE WMAP HAZE FROM THE GALACTIC CENTER REGION DUE TO MASSIVE STAR EXPLOSIONS AND A REDUCED COSMIC RAY SCALE HEIGHT

One important prediction of acceleration of particles in the supernova caused shock in the magnetic wind of exploding Wolf–Rayet and red supergiant stars is the production of an energetic particle component with an E−2 spectrum at a level on the order of 1% of the full cosmic ray electron population. After allowing for transport effects, so steepening the spectrum to E−7/3, this component as cosmic ray electrons readily explains the WMAP haze from the Galactic center region in spectrum, intensity, and radial profile; this requires the diffusion timescale for cosmic rays in the Galactic center region to be much shorter than in the solar neighborhood: the energy for cosmic ray electrons at the transition between diffusion dominance and loss dominance is shifted to considerably higher particle energy. We predict that more precise observations will find a radio spectrum of ν−2/3, at higher frequencies ν−1, and at yet higher frequencies finally ν−3/2.
MAGNETICALLY DRIVEN WINDS FROM DIFFERENTIALLY ROTATING NEUTRON STARS AND X-RAY AFTERGLOWS OF SHORT GAMMA-RAY BURSTS

Besides being among the most promising sources of gravitational waves, merging neutron star binaries also represent a leading scenario to explain the phenomenology of short gamma-ray bursts (SGRBs). Recent observations have revealed a large subclass of SGRBs with roughly constant luminosity in their X-ray afterglows, lasting 10–104 s. These features are generally taken as evidence of a long-lived central engine powered by the magnetic spin-down of a uniformly rotating, magnetized object. We propose a different scenario in which the central engine powering the X-ray emission is a differentially rotating hypermassive neutron star (HMNS) that launches a quasi-isotropic and baryon-loaded wind driven by the magnetic field, which is built-up through differential rotation. Our model is supported by long-term, three-dimensional, general-relativistic, and ideal magnetohydrodynamic simulations, showing that this isotropic emission is a very robust feature. For a given HMNS, the presence of a collimated component depends sensitively on the initial magnetic field geometry, while the stationary electromagnetic luminosity depends only on the magnetic energy initially stored in the system. We show that our model is compatible with the observed timescales and luminosities and express the latter in terms of a simple scaling relation.
Absorption features caused by oscillations of electrons on the surface of a quark star

If quark stars exist, they may be enveloped in thin electron layers (electron seas), which uniformly surround the entire star. These layers will be affected by the magnetic fields of quark stars in such a way that the electron seas would transmit hydromagnetic cyclotron waves, as studied in this paper. Particular attention is devoted to vortex hydrodynamical oscillations of the electron sea. The frequency spectrum of these oscillations is derived in analytic form. If the thermal X-ray spectra of quark stars are modulated by vortex hydrodynamical vibrations, the thermal spectra of compact stars, foremost central compact objects (CCOs) and X-ray dim isolated neutron stars (XDINSs), could be used to verify the existence of these vibrational modes observationally. The central compact object 1E 1207.4-5209 appears particularly interesting in this context, since its absorption features at 0.7 keV and 1.4 keV can be comfortably explained in the framework of the hydro-cyclotron oscillation model.
String Evolution with Friction

We study the effects of friction on the scaling evolution of string networks in condensed matter and cosmological contexts. We derive a generalized `one-scale' model with the string correlation length $L$ and velocity $v$ as dynamical variables. In non-relativistic systems, we obtain a well-known $L\propto t^{1/2}$ law, showing that loop production is important. For electroweak cosmic strings, we show transient damped epoch scaling with $L\propto t^{5/4}$ (or, in the matter era, $L\propto t^{3/2}$). A low initial density implies an earlier period with $L\propto t^{1/2}$. For GUT strings, the approach to linear scaling $L\propto t$ is faster than previously estimated.
Overlapping inflows as catalysts of AGN activity – II. Relative importance of turbulence and inflow–disc interaction

The main challenge for understanding the fuelling of supermassive black holes in active galactic nuclei is not to account for the source of fuel, but rather to explain its delivery from the boundaries of the black hole sphere of influence (10-100 pc) down to sub-parsec scales. In this work, we report on a series of numerical experiments aimed at exploring in further depth our model of "overlapping inflow events" as catalysts for rapid accretion, seeding a turbulent field in the infalling gas. We initially set a gaseous shell in non-equilibrium rotation around a supermassive black hole. After infall, the shell stalls in a disc-like structure. A second shell is then set in either co-rotation or counter-rotation with respect to the first and is let to impinge on the previously-formed disc. We find that combined turbulence and overlap significantly enhance accretion in counter-rotating inflows, while turbulence dominates for co-rotating inflows. The leftovers of overlapping inflows are warped nuclear discs, whose morphology depends on the relative orientation and angular momentum of the disc and the shell. Overlapping inflows leave observational signatures in the gas rotation curves.
argot: accelerated radiative transfer on grids using oct‐tree

We present two types of numerical prescriptions that accelerate the radiative transfer calculation around point sources within a three-dimensional Cartesian grid by using the oct-tree structure for the distribution of radiation sources. In one prescription, distant radiation sources are grouped as a bright extended source when the group’s angular size, θs, is smaller than a critical value, θcrit, and radiative transfer is solved on supermeshes whose angular sizes are similar to that of the group of sources. The supermesh structure is constructed by coarse-graining the mesh structure. With this method, the computational time scales with Nm log(Nm)log(Ns) where Nm and Ns are the number of meshes and that of radiation sources, respectively. While this method is very efficient, it inevitably overestimates the optical depth when agroup of sources acts as an extended powerful radiation source and affects distant meshes. In the other prescription, a distant group of sources is treated as a bright point source ignoring the spatial extent of the group and the radiative transfer is solved on the meshes rather than the supermeshes. This prescription is simply a grid-based version of START by Hasegawa & Umemura and yields better results in general with slightly more computational cost (/ N 4/3 m log(Ns)) than the supermesh prescription. Our methods can easily be implemented to any grid-based hydrodynamic codes and are well-suited to the adaptive mesh refinement methods.
Degree distribution of complex networks from statistical mechanics principles

In this paper we describe the emergence of scale-free degree distributions from statistical mechanics principles. We define an energy associated to a degree sequence as the logarithm of the number of indistinguishable simple networks it is possible to draw given the degree sequence. Keeping fixed the total number of nodes and links, we show that the energy of scale-free distribution is much higher than the energy associated to the degree sequence of regular random graphs. This results unable us to estimate the annealed average of the number of distinguishable simple graphs it is possible to draw given a scale-free distribution with structural cutoff. In particular we shaw that this number for large networks is strongly suppressed for power -law exponent \gamma->2.
Biomineral Amorphous Lasers through Light‐Scattering Surfaces Assembled by Electrospun Fiber Templates

New materials aim at exploiting the great control of living organisms over molecular architectures and minerals. Optical biomimetics has been widely developed by microengineering, leading to photonic components with order resembling those found in plants and animals. These systems, however, are realized by complicated and adverse processes. Here we show how biomineralization might enable the one‐step generation of components for amorphous photonics, in which light is made to travel through disordered scattering systems, and particularly of active devices such as random lasers, by using electrospun fiber templates. The amount of bio‐enzymatically produced silica is related to light‐scattering capacity and the resulting organosilica surfaces exhibit a transport mean free path for light as low as 3 μm, and lasing with linewidth below 0.2 nm. The resulting, complex optical material is characterized and modelled to elucidate scattered fields and lasing performance. Tightly‐controlled nanofabrication of direct biological inspiration establishes a new concept for the additive manufacturing of engineered light‐diffusing materials and photonic components, not addressed by existing technologies.
Holographic Josephson Junction in 3+1 dimensions

In arXiv:1101.3326[hep-th], a (2+1)-dimensional holographic Josephson junction was constructed, and it was shown that the DC Josephson current is proportional to the sine of the phase difference across the junction. In this paper, we extend this study to a holographic description for the (3+1)-dimensional holographic DC Josephson junction. By solving numerically the coupled differential equations, we also obtain the familiar characteristics of Josephson junctions.
Soliton attenuation and emergent hydrodynamics in fragile matter

Disordered packings of soft grains are fragile mechanical systems that lose rigidity upon lowering the external pressure toward zero. At zero pressure, we find that any infinitesimal strain impulse propagates initially as a nonlinear solitary wave progressively attenuated by disorder. We demonstrate that the particle fluctuations generated by the solitary-wave decay can be viewed as a granular analogue of temperature. Their presence is manifested by two emergent macroscopic properties absent in the unperturbed granular packing: a finite pressure that scales with the injected energy (akin to a granular temperature) and an anomalous viscosity that arises even when the microscopic mechanisms of energy dissipation are negligible. Consistent with the interpretation of this state as a fluidlike thermalized state, the shear modulus remains zero. Further, we follow in detail the attenuation of the initial solitary wave, identifying two distinct regimes—an initial exponential decay, followed by a longer power-law decay—and suggest simple models to explain these two regimes.
Strain-induced metal-insulator transition in ultrathin films of SrRuO 3

The ultrathin film limit has been shown to be a rich playground for unusual low-dimensional physics. Taking the example of ${\mathrm{SrRuO}}_{3}$, which is ferromagnetic and metallic at the bulk limit, one finds that it becomes antiferromagnetic and insulating at the three-monolayers limit when grown on ${\mathrm{SrTiO}}_{3}$. The origin of the insulating state is traced to strongly orbital-dependent exchange splittings. A modest compressive strain of 1% of the ${\mathrm{SrTiO}}_{3}$ substrate is then found to drive the system into a highly confined two-dimensional 100% spin polarized metallic state. This metal-insulator transition driven by a modest strain could be useful in two-state device applications.
UNSUPERVISED TRANSIENT LIGHT CURVE ANALYSIS VIA HIERARCHICAL BAYESIAN INFERENCE

Historically, light curve studies of supernovae (SNe) and other transient classes have focused on individual objects with copious and high signal-to-noise observations. In the nascent era of wide field transient searches, objects with detailed observations are decreasing as a fraction of the overall known SN population, and this strategy sacrifices the majority of the information contained in the data about the underlying population of transients. A population level modeling approach, simultaneously fitting all available observations of objects in a transient sub-class of interest, fully mines the data to infer the properties of the population and avoids certain systematic biases. We present a novel hierarchical Bayesian statistical model for population level modeling of transient light curves, and discuss its implementation using an efficient Hamiltonian Monte Carlo technique. As a test case, we apply this model to the Type IIP SN sample from the Pan-STARRS1 Medium Deep Survey, consisting of 18,837 photometric observations of 76 SNe, corresponding to a joint posterior distribution with 9176 parameters under our model. Our hierarchical model fits provide improved constraints on light curve parameters relevant to the physical properties of their progenitor stars relative to modeling individual light curves alone. Moreover, we directly evaluate the probability for occurrence rates of unseen light curve characteristics from the model hyperparameters, addressing observational biases in survey methodology. We view this modeling framework as an unsupervised machine learning technique with the ability to maximize scientific returns from data to be collected by future wide field transient searches like LSST.
Collision-free motion planning for fiber positioner robots: discretization of velocity profiles

The next generation of large-scale spectroscopic survey experiments such as DESI, will use thousands of fiber positioner robots packed on a focal plate. In order to maximize the observing time with this robotic system we need to move in parallel the fiber-ends of all positioners from the previous to the next target coordinates. Direct trajectories are not feasible due to collision risks that could undeniably damage the robots and impact the survey operation and performance. We have previously developed a motion planning method based on a novel decentralized navigation function for collision-free coordination of fiber positioners. The navigation function takes into account the configuration of positioners as well as their envelope constraints. The motion planning scheme has linear complexity and short motion duration (2.5 seconds with the maximum speed of 30 rpm for the positioner), which is independent of the number of positioners. These two key advantages of the decentralization designate the method as a promising solution for the collision-free motion-planning problem in the next-generation of fiber-fed spectrographs. In a framework where a centralized computer communicates with the positioner robots, communication overhead can be reduced significantly by using velocity profiles consisting of a few bits only. We present here the discretization of velocity profiles to ensure the feasibility of a real-time coordination for a large number of positioners. The modified motion planning method that generates piecewise linearized position profiles guarantees collision-free trajectories for all the robots. The velocity profiles fit few bits at the expense of higher computational costs.
But does the nudge fit? Institutional structure and behavioural insights

Behavioural science has found growing application in applied public policy settings, offering a vast literature to bring to bear on apparent cognitive errors. The potential, however, is not without peril. Policymakers and scholars may draw unwarranted confidence that successful behavioural interventions from elsewhere will replicate in their institutional settings. In this research, I partner with Minneapolis Public Housing and use a design-based approach to identify interventions that can reduce eviction actions. This study presents three vignettes that demonstrate and categorize the mistakes behavioural science can make when it fails to understand how formal and informal institutional features influence decision-making. But, in integrating methods and theories from the design sciences, public policy and public administration, we have the potential to create behavioural interventions that fit the social context.
Particles and fields in fluid turbulence

The understanding of fluid turbulence has considerably progressed in recent years. The application of the methods of statistical mechanics to the description of the motion of fluid particles, i.e. to the Lagrangian dynamics, has led to a new quantitative theory of intermittency in turbulent transport. The first analytical description of anomalous scaling laws in turbulence has been obtained. The underlying physical mechanism reveals the role of statistical integrals of motion in non-equilibrium systems. For turbulent transport, the statistical conservation laws are hidden in the evolution of groups of fluid particles and arise from the competition between the expansion of a group and the change of its geometry. By breaking the scale-invariance symmetry, the statistically conserved quantities lead to the observed anomalous scaling of transported fields. Lagrangian methods also shed new light on some practical issues, such as mixing and turbulent magnetic dynamo.
On the Inadmissibility of Non-evolutionary Shocks

In recent years, numerical solutions of the equations of compressible magnetohydrodynamic ﬂows have been found to contain intermediate shocks for certain kinds of problems. Since these results would seem to be in conﬂict with the classical theory of magnetohydrodynamic shocks, they have stimulated attempts to reexamine various aspects of this theory, in particular the role of dissipation. In this paper we study the general relationship between the evolutionary conditions for discontinuous solutions of the dissipation-free system and the existence and uniqueness of steady dissipative shock structures for systems of quasilinear conservation laws with a concave entropy function. Our results conﬁrm the classical theory. We also show that the appearance of intermediate shocks in numerical simulations can be understood in terms of the properties of the equations of planar magnetohydrodynamics for which some of these shocks turn out to be evolutionary. Finally, we discuss ways in which numerical schemes can be modiﬁed in order to avoid the appearance of intermediate shocks in simulations with such symmetry.
Customer engagement behaviour in the media and technology industry: a quantitative content analysis of content types and COVID-19 context

ABSTRACT Brand pages on social networking sites represent excellent vehicles for customer relationship management. These pages enable companies to interact with their customers and to foster their engagement. This study examines the relationship between, and moderating impact of, customer engagement behaviour and a COVID-19-related context as well as content types. The content of 1,946 company-generated Facebook brand posts of 16 media and technology companies was analysed. A hierarchical regression analysis was used to test the hypotheses. The results show that a COVID-19-related context and the content type are associated with customer engagement behaviour. These factors both partly interact and directly correlate with customer engagement behaviour. This study contributes to the literature by establishing (crisis-related) social media guidelines for media and technology companies.
A spatial data model for accessibility with indoor temporal changes

Indoor accessibility is often evaluated with the networks extracted from buildings. For instance, circulation networks with depth cost are applied to floor design. A group of data models supports the extraction of indoor networks from buildings, and these networks are widely used to evaluate the accessibility of users. However, the existing cases are mostly devised for static environments, that is, without consideration of dynamic obstacles. This assumption may contradict the fact of daily changes such as pedestrian flow and temporal blockage. Except emergency scenarios, these daily temporal changes can interrupt the continuous movement of a user, and they shall be considered for data modeling of indoor networks. Thus, this article proposes a concise data model which can manage daily temporal changes of accessibility and support related accessibility queries. In the data model, we consider indoor accessibility on two levels of detail, that is, the room and sub‐room levels. On the room level, we revise a gravity model to measure the accessibility variation of rooms influenced by temporal obstacles. On the sub‐room level, we continuously update obstacle‐avoiding networks adapted to temporal obstacles. In this case, the accessibility of a user at any location can be assessed and time‐dependent accurate routes can be planned at different moments. We implemented this spatial data model in the DBMS PostgreSQL and its feasibility was demonstrated with the test in a campus building. The data model can be applied to daily checks of user accessibility and can be further incorporated with indoor sensor systems and simulation models to predict accessibility variation.
An Energy Storage-Based Railway Power Flow Controller With Partial Compensation Strategy

Focusing on the grid-connection issues and the generated regenerative braking energy (RBE) in the traction power supply system (TPSS), this paper proposes an energy storage-based railway power flow controller (ES-RPFC) with partial compensation strategy (PCS) for grid-connection performance improvement and RBE utilization. The relationship of the primary power factor (PF), the two-phase compensated power, and the converters’ rating is investigated. On this basis, a PCS is developed to reduce the converters’ rating under the premise of satisfying the concerned grid-connection indices. Then, taking the developed PCS into account, a comprehensive power-flow management scheme for ES-RPFC under different operation scenarios is established, and the control strategy of the converter-level controller is given. Finally, the proposal is verified to be feasible and effective by means of both simulation and hardware-in-loop (HIL) experimental results.