cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
The powder keg: Lessons learned about clinical staff preparedness during the early phase of the COVID-19 pandemic
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2020
Subjects: Health care professionals
Health care workers
Hospital emergency
Hospital preparedness
SARS-CoV-2, COVID-19

description: © 2020 Association for Professionals in Infection Control and Epidemiology, Inc. Background: Little is known about clinical staff's perspectives on preparedness for a pandemic. The purpose of this study was to obtain various clinical staff perspectives about preparedness to meet the demands for care during the early phase of the SARS-CoV-2 (COVID-19) pandemic. Methods: We conducted a qualitative study using semistructured in-person interviews from March 2020 to April 2020 at a large tertiary academic urban hospital center. Interview guides were informed by the Resilience Framework for Public Health Emergency Preparedness and analyzed using a directed content analysis approach. Results: Fifty-five clinical staff participated in the study. Three themes emerged from the data (1) Risk assessment and planning: “The powder keg,” (2) Innovative evolution of roles and responsibilities, and (3) Pandemic response and capacity. In the early phases of the pandemic, participants reported varying levels of risks for dying. However, most participants adapted to practice changes and became innovative in their roles over time. Hierarchies were less relevant during care delivery, whereas team collaboration became crucial in managing workforce capacity. Discussion: As the pandemic progressed, staff preparedness evolved through a trial-and-error approach. Conclusions: The pandemic is evolving as is clinical staff preparedness to meet the demands of a pandemic. In order to get a grasp on the crisis, clinical staff relied on each other and resorted to new workarounds.
A Case Study Evaluating the Risk of Infection from Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) in a Hospital Setting Through Bioaerosols
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2019
Subjects: Hospital
MERS-CoV
mitigation
QMRA
risk characterization

description: © 2019 Society for Risk Analysis Middle Eastern respiratory syndrome, an emerging viral infection with a global case fatality rate of 35.5%, caused major outbreaks first in 2012 and 2015, though new cases are continuously reported around the world. Transmission is believed to mainly occur in healthcare settings through aerosolized particles. This study uses Quantitative Microbial Risk Assessment to develop a generalizable model that can assist with interpreting reported outbreak data or predict risk of infection with or without the recommended strategies. The exposure scenario includes a single index patient emitting virus-containing aerosols into the air by coughing, leading to short- and long-range airborne exposures for other patients in the same room, nurses, healthcare workers, and family visitors. Aerosol transport modeling was coupled with Monte Carlo simulation to evaluate the risk of MERS illness for the exposed population. Results from a typical scenario show the daily mean risk of infection to be the highest for the nurses and healthcare workers (8.49 × 10−4 and 7.91 × 10−4, respectively), and the lowest for family visitors and patients staying in the same room (3.12 × 10−4 and 1.29 × 10−4, respectively). Sensitivity analysis indicates that more than 90% of the uncertainty in the risk characterization is due to the viral concentration in saliva. Assessment of risk interventions showed that respiratory masks were found to have a greater effect in reducing the risks for all the groups evaluated (>90% risk reduction), while increasing the air exchange was effective for the other patients in the same room only (up to 58% risk reduction).
Studying the Sources of Cosmic Reionization with 21-cm Fluctuations
Creators: name: Barkana, Rennan
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We explore the ability of measurements of the 21-cm power spectrum during reionization to enable the simultaneous reconstruction of the reionization history and the properties of the ionizing sources. For various sets of simulated 21-cm measurements, we perform maximum likelihood fits in order to constrain the reionization and galaxy formation histories. We employ a flexible six-parameter model that parametrizes the uncertainties in the properties of high-redshift galaxies. The computational speed needed is attained through the use of an analytical model that is in reasonable agreement with numerical simulations of reionization. We find that one-year observations with the MWA array should measure the cosmic ionized fraction to ~ 1% accuracy at the very end of reionization, and a few percent accuracy around the mid-point of reionization. The mean halo mass of the ionizing sources should be measureble to 10% accuracy when reionization is 2/3 of the way through, and to 20% accuracy throughout the central stage of reionization, if this mass is anywhere in the range 1/3 to 100 billion solar masses.
description: 11 pages, 11 figures, submitted to MNRAS
Study of molecular mechanisms in cardio- and neuroprotection and possibility of modulation by nutraceutical phytocomponents
Creators: name: Fabbri, Daniele <1981>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: BIO/10 Biochimica

description: Ischemic preconditioning is a complex cardioprotective phenomenon that involves adaptive changes in cells and molecules. This adaptation occurs in a biphasic pattern: an early phase which develops after 1-2 h, and a late phase that develops after 12-24 h. While it is widely accepted that reactive oxygen species (ROS) are strongly involved in triggering ischemic preconditiong, it is not clear if they play a major role in the early or late phase of preconditioning and which are the mechanisms involved. 
Methylglyoxal, a metabolic compound formed mainly from the glycolytic intermediate glyceraldehyde-3-phosphate., is a precursor of advanced glycation end product (AGEs) .It is more reactive than glucose and shows a stronger ability to  cross-link with protein amino groups to form AGEs. Methylglyoxal induced cytotoxicity may be at least partially responsible for cardiovascular and Alzheimer diseases. Methylglyoxal omeostasis is controlled by the glyoxalase system that consists of two enzyme, glyoxalase 1 (GLO1) and glyoxalase 2. In a recent study it was demonstrated that the transcriptional levels of GLO1 are controlled by NF-E2-related factor 2 (Nrf2). The isothiocyanate sulforaphane, derived from the hydrolysis of glucoraphanin abundantly present in broccoli, represents one of the most potent inducers of phase II enzymes through the Keap1–Nrf2 pathway.
The aim of this thesis was evaluated molecular mechanisms in cardio- and neuroprotection and the possibility of modulation by nutraceutical phytocomponents
This thesis show to one side that the protection induced by H2O2 is mediated by detoxifying and antioxidant phase II enzymes induction, regulated, not only by transcriptional factor Nrf2, but also by Nrf1; on the other side our data represent an innovative result because for the first time it was demonstrated the possibility of inducing GLO1 by SF supplementation.
Multi-Point Propagators in Cosmological Gravitational Instability
Creators: name: Bernardeau, Francis
name: Crocce, Martin
name: Scoccimarro, Roman
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We introduce the concept of multi-point propagators between linear cosmic fields and their nonlinear counterparts in the context of cosmological perturbation theory. Such functions express how a non-linearly evolved Fourier mode depends on the full ensemble of modes in the initial density field. We identify and resum the dominant diagrams in the large-$k$ limit, showing explicitly that multi-point propagators decay into the nonlinear regime at the same rate as the two-point propagator. These analytic results generalize the large-$k$ limit behavior of the two-point propagator to arbitrary order. We measure the three-point propagator as a function of triangle shape in numerical simulations and confirm the results of our high-$k$ resummation. We show that any $n-$point spectrum can be reconstructed from multi-point propagators, which leads to a physical connection between nonlinear corrections to the power spectrum at small scales and higher-order correlations at large scales. As a first application of these results, we calculate the reduced bispectrum at one-loop in renormalized perturbation theory and show that we can predict the decrease in its dependence on triangle shape at redshift zero, when standard perturbation theory is least successful.
description: 21 pages, 14 figures. Minor changes to match published version (Fig 11 changed, added reference)
Criticality in the collapse of spherically symmetric massless scalar fields in semi-classical loop quantum gravity
Creators: name: Benítez, Florencia
name: Gambini, Rodolfo
name: Liebling, Steven L.
name: Pullin, Jorge
Publisher: name: arXiv
Year: 2021
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In a recent paper we showed that the collapse to a black hole in one-parameter families of initial data for massless, minimally coupled scalar fields in spherically symmetric semi-classical loop quantum gravity exhibited a universal mass scaling similar to the one in classical general relativity. In particular, no evidence of a mass gap appeared as had been suggested by previous studies. The lack of a mass gap indicated the possible existence of a self-similar critical solution as in general relativity. Here we provide further evidence for its existence. Using an adaptive mesh refinement code, we show that "echoes" arise as a result of the discrete self-similarity in space-time. We also show the existence of "wiggles" in the mass scaling relation, as in the classical theory. The results from the semi-classical theory agree well with those of classical general relativity unless one takes unrealistically large values for the polymerization parameter.
description: 7 pages, RevTex
Measurements of the separated longitudinal structure function FL from hydrogen and deuterium targets at low Q2
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2018
Subjects: nucl-ex
hep-ex

description: © 2018 American Physical Society. Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the partonic dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available in particular for the longitudinal structure function. Here, we present separated structure functions for hydrogen and deuterium at low four-momentum transfer squared, Q2<1GeV2, and compare them with parton distribution parametrization and kT factorization approaches. While differences are found, the parametrizations generally agree with the data, even at the very low-Q2 scale of the data. The deuterium data show a smaller longitudinal structure function and a smaller ratio of longitudinal to transverse cross section, R, than the proton. This suggests either an unexpected difference in R for the proton and the neutron or a suppression of the gluonic distribution in nuclei.
Dissipation-driven quantum phase transition in superconductor-graphene systems
Creators: name: Lutchyn, Roman M.
name: Galitski, Victor
name: Refael, Gil
name: Sarma, S. Das
Publisher: name: arXiv
Year: 2008
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We show that a system of Josephson junctions coupled via low-resistance tunneling contacts to graphene substrate(s) may effectively operate as a current switching device. The effect is based on the dissipation-driven superconductor-to-insulator quantum phase transition, which happens due to the interplay of the Josephson effect and Coulomb blockade. Coupling to a graphene substrate with gapless excitations further enhances charge fluctuations favoring superconductivity. The effect is shown to scale exponentially with the Fermi energy in graphene, which can be controlled by the gate voltage. We develop a theory, which quantitatively describes the quantum phase transition in a two-dimensional Josephson junction array, but it is expected to provide a reliable qualitative description for one-dimensional systems as well. We argue that the local effect of dissipation-induced enhancement of superconductivity is very robust and a similar sharp crossover should be present in finite Josephson junction chains.
description: 4 pages, 3 figures
Nearly constant Q dissipative models and wave equations for general viscoelastic anisotropy
Creators: name: Hao, Qi
name: Greenhalgh, Stewart
Publisher: name: arXiv
Year: 2021
Subjects: subject: Geophysics (physics.geo-ph)
subject: Classical Physics (physics.class-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The quality factor (Q) links seismic wave energy dissipation to physical properties of the Earth's interior, such as temperature, stress and composition. Frequency independence of Q, also called constant Q for brevity, is a common assumption in practice for seismic Q inversions. Although exactly and nearly constant Q dissipative models are proposed in the literature, it is inconvenient to obtain constant Q wave equations in differential form, which explicitly involve a specified Q parameter. In our recent research paper, we proposed a novel weighting function method to build the first- and second-order nearly constant Q dissipative models. Of importance is the fact that the wave equations in differential form for these two models explicitly involve a specified Q parameter. This behavior is beneficial for time-domain seismic waveform inversion for Q, which requires the first derivative of wavefields with respect to Q parameters. In this paper, we extend the first- and second-order nearly constant Q models to the general viscoelastic anisotropic case. We also present a few formulation of the nearly constant Q viscoelastic anisotropic wave equations in differential form.
Electrospun Polymeric Scaffolds with Enhanced Biomimetic Properties for Tissue Engineering Applications
Creators: name: Fiorani, Andrea <1985>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: CHIM/04 Chimica industriale

description: This PhD Thesis is focused on the development of fibrous polymeric scaffolds for tissue engineering applications and on the improvement of scaffold biomimetic properties. Scaffolds were fabricated by electrospinning, which allows to obtain scaffolds made of polymeric micro or nanofibers. Biomimetism was enhanced by following two approaches: (1) the use of natural biopolymers, and (2) the modification of the fibers surface chemistry.
Gelatin was chosen for its bioactive properties and cellular affinity, however it lacks in mechanical properties. This problem was overcome by adding poly(lactic acid) to the scaffold through co-electrospinning and mechanical properties of the composite constructs were assessed. Gelatin effectively improves cell growth and viability and worth noting, composite scaffolds of gelatin and poly(lactic acid) were more effective than a plain gelatin scaffold.
Scaffolds made of pure collagen fibers were fabricated. Modification of collagen triple helix structure in electrospun collagen fibers was studied. Mechanical properties were evaluated before and after crosslinking. The crosslinking procedure was developed and optimized by using - for the first time on electrospun collagen fibers - the crosslinking reactant 1,4-butanediol diglycidyl ether, with good results in terms of fibers stabilization. Cell culture experiments showed good results in term of cell adhesion and morphology.
The fiber surface chemistry of electrospun poly(lactic acid) scaffold was modified by plasma treatment. Plasma did not affect thermal and mechanical properties of the scaffold, while it greatly increased its hydrophilicity  by the introduction of carboxyl groups at the fiber surface. This fiber functionalization enhanced the fibroblast cell viability and spreading.
Surface modifications by chemical reactions were conducted on electrospun scaffolds made of a polysophorolipid. The aim was to introduce a biomolecule at the fiber surface. By developing a series of chemical reactions, one oligopeptide every three repeating units of polysophorolipid was grafted at the surface of electrospun fibers.
Electrically Induced Dirac Fermions in Graphene Nanoribbons
Creators: name: Pizzochero, Michele
name: Tepliakov, Nikita V.
name: Mostofi, Arash A.
name: Kaxiras, Efthimios
Publisher: name: arXiv
Year: 2021
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Graphene nanoribbons are widely regarded as promising building blocks for next-generation carbon-based devices. A critical issue to their prospective applications is whether and to what degree their electronic structure can be externally controlled. Here, we combine simple model Hamiltonians with extensive first-principles calculations to investigate the response of armchair graphene nanoribbons to transverse electric fields. Such fields can be achieved either upon laterally gating the nanoribbon or incorporating ambipolar chemical co-dopants along the edges. We reveal that the field induces a semiconductor-to-semimetal transition, with the semimetallic phase featuring zero-energy Dirac fermions that propagate along the armchair edges. The transition occurs at critical fields that scale inversely with the width of the nanoribbons. These findings are universal to group-IV honeycomb lattices, including silicene and germanene nanoribbons, irrespective of the type of edge termination. Overall, our results create new opportunities to electrically engineer Dirac fermions in otherwise semiconducting graphene-like nanoribbons.
Trigonometric Parallaxes for Two Late-Type Subdwarfs: LSR1425+71 (sdM8.0) and the Binary LSR1610-00 (sd?M6pec)
Creators: name: Dahn, C. C.
name: Harris, H. C.
name: Levine, S. E.
name: Tilleman, T.
name: Monet, A. K. B.
name: Stone, R. C.
name: Guetter, H. H.
name: Canzian, B.
name: Pier, J. R.
name: Hartkopf, W. I.
name: Liebert, J.
name: Cushing, M.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Trigonometric parallax astrometry and BVI photometry are presented for two late-type subdwarf candidates, LSR1425+71 (sdM8.0) and LSR1610-00 (sd?M6pec). For the former we measure an absolute parallax of 13.37+/-0.51 mas yielding Mv=15.25+/-0.09. The astrometry for LSR1610-00 shows that this object is an astrometric binary with a period of 1.66+/-0.01 yr. The photocentric orbit is derived from the data; it has a moderate eccentricity (e ~ 0.44+/-0.02) and a semi-major axis of 0.28+/-0.01 AU based on our measured absolute parallax of 31.02+/-0.26 mas. Our radial velocity measure of -108.1+/-1.6 km/s for LSR1610-00 at epoch 2006.179, when coupled with the observation of -95+/-1 km/s at epoch 2005.167 by Reiners & Basri, indicates a systemic radial velocity of -101+/-1 km/s for the LSR1610-00AB pair. The galactic velocity components for LSR1425+71 and LSR1610-00AB -- (U,V,W)=(84+/-6, -202+/-13, 66+/-14) km/s and (U,V,W)=(36+/-2, -232+/-2, -61+/-2) km/s, respectively. For both stars, the velocities are characteristic of halo population kinematics. However, modeling shows that both stars have orbits around the galaxy with high eccentricity that pass remarkably close to the galactic center. LSR1425+71 has a luminosity and colors consistent with its metal-poor subdwarf spectral classification, while LSR1610-00 has a luminosity and most colors indicative of being only mildly metal-poor, plus a uniquely red B-V color. The companion to LSR1610-00 must be a low-mass, substellar brown dwarf. We speculate on the paradoxical nature of LSR1610-00 and possible sources of its peculiarities.
description: Accepted for ApJ. 37 pages, including 8 figures
Le paysage comme fragmentation de l'Esthetique de la nature a l'Epoque contemporaine. Les experiences poetiques de zanzotto, jaccottet at heaney
The landscape as fragmentation of the aesthetics of nature in the present-day. The poetic experiences of Zanzotto, Jaccottet and Heaney
Creators: name: Gaio, Daniele <1982>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2014
Subjects: L-FIL-LET/14 Critica letteraria e letterature comparate

description: In this work, we have considered the theme of landscape in the poetry of Andrea Zanzotto, Philippe Jaccottet and Seamus Heaney within the perspective of a fragmentation of the aesthetics of nature. To that end, the most advanced theories of aesthetics applied to nature, such as environmental Aesthetics and Aesthetik der Natur (also known as ökologische Aesthetik) have been taken into account. The philosophical perspective of Paolo D’Angelo, insights from geography (in particular from the works of Franco Farinelli) and from ecology (considering the contributions of Gilles Clément to this discipline) have also been useful.
We have argued that the poetic experiences of Zanzotto, Jaccottet and Heaney follow a similar path, each starting from the fusion between the poetic subject and landscape to reach a two-way relationship between them. In this interpretation, the concept of landscape has been considered, according to Michel Collot’s theory of pensée-paysage, as a phenomenon.
 
The poetic texts have been analysed under the lenses of linguistic, stylistic and rhetorical approaches, consistent with the idea that every text must be studied within its context, as every poetic experience is constituted of three elements: the poetic subject, his language and his world, the latest being shaped by and shaping the subject’s position and the perspectives related to it: that is his discourse to the world and in this world.
Stars lensed by the supermassive black hole in the center of the Milky Way: predictions for ELT, TMT, GMT, and JWST
Creators: name: Michałowski, Michał J.
name: Mróz, Przemek
Publisher: name: arXiv
Year: 2021
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Gravitational lensing is an important prediction of general relativity, providing both its test and a tool to detect faint but amplified sources and to measure masses of lenses. For some applications (e.g. testing the theory), a point source lensed by a point-like lens would be more advantageous. However, until now only one gravitationally lensed star has been resolved. The future telescopes will resolve very small lensing signatures for stars orbiting the supermassive black hole (SMBH) in the center of the Milky Way. The lensing signatures should however be easier to detect for background stars. We predict that ELT, TMT, and GMT will resolve the lensed images of around 100 (60) stars in the disk and 30 (20) stars in the bulge in the background of the SMBH, down to 28 (27) mag (Vega) limits at K-band, requiring 5 (1) hr of integration. In order to detect several such stars one needs the limit of at least 24 mag. With a decade-long monitoring one can also detect the rotation of the lensed images. The detection of elongated images will not be possible, because this would require a nearly perfect source-lens alignment. JWST will likely be limited by the confusion caused by stars near the Galactic center. The detection of such lensed images will provide a very clean test of general relativity, when combined with the SMBH mass measurement from orbital motions of stars, and accurate measurements of the SMBH properties, because both the source and the lens can be considered point-like.
description: ApJ Letters, accepted; 9 pages, 4 figures, 1 table
Effects of the $g$-factor in semi-classical kinetic plasma theory
Creators: name: Brodin, Gert
name: Marklund, Mattias
name: Zamanian, Jens
name: Ericsson, Asa
name: Mana, Piero L.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analysing the linear properties, it is found that new types of wave-particle resonances are possible, that depend directly on the anomalous magnetic moment of the electron. As a result new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.
description: 4 pages, two figures, version to appear in Physical Review Letters
Wall Crossing, Discrete Attractor Flow and Borcherds Algebra
Creators: name: Cheng, Miranda C. N.
name: Verlinde, Erik P.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The appearance of a generalized (or Borcherds-) Kac-Moody algebra in the spectrum of BPS dyons in N=4, d=4 string theory is elucidated. From the low-energy supergravity analysis, we identify its root lattice as the lattice of the T-duality invariants of the dyonic charges, the symmetry group of the root system as the extended S-duality group PGL(2,Z) of the theory, and the walls of Weyl chambers as the walls of marginal stability for the relevant two-centered solutions. This leads to an interpretation for the Weyl group as the group of wall-crossing, or the group of discrete attractor flows. Furthermore we propose an equivalence between a "second-quantized multiplicity" of a charge- and moduli-dependent highest weight vector and the dyon degeneracy, and show that the wall-crossing formula following from our proposal agrees with the wall-crossing formula obtained from the supergravity analysis. This can be thought of as providing a microscopic derivation of the wall-crossing formula of this theory.
description: This is a contribution to the Special Issue on Kac-Moody Algebras and Applications, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/
Zero-temperature Phase Diagram of Two Dimensional Hubbard Model
Creators: name: Inaba, K.
name: Koga, A.
name: Suga, S.
name: Kawakami, N.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate the two-dimensional Hubbard model on the triangular lattice with anisotropic hopping integrals at half filling. By means of a self-energy functional approach, we discuss how stable the non-magnetic state is against magnetically ordered states in the system. We present the zero-temperature phase diagram, where the normal metallic state competes with magnetically ordered states with $(π, π)$ and $(2π/3, 2π/3)$ structures. It is shown that a non-magnetic Mott insulating state is not realized as the ground state, in the present framework, but as a meta-stable state near the magnetically ordered phase with $(2π/3, 2π/3)$ structure.
description: 4 pages, 4 figures
Formation and evolution of protostellar accretion discs. II. From 3D simulation to a simple semi-analytic model of Class 0/I discs
Creators: name: Xu, Wenrui
name: Kunz, Matthew W.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We use a 3D radiative non-ideal magnetohydrodynamic (MHD) simulation to investigate the formation and evolution of a young protostellar disc from a magnetized pre-stellar core. The simulation covers the first ${\sim}10~{\rm kyr}$ after protostar formation, and shows a massive, weakly magnetized disc with radius that initially grows and then saturates at ${\sim}30~{\rm au}$. The disc is gravitationally unstable with prominent large-amplitude spiral arms. We use our simulation results and a series of physical arguments to construct a predictive and quantitative physical picture of Class 0/I protostellar disc evolution from several aspects, including (i) the angular-momentum redistribution in the disc, self-regulated by gravitational instability to make most of the disc marginally unstable; (ii) the thermal profile of the disc, well-approximated by a balance between radiative cooling and accretion heating; and (iii) the magnetic-field strength and magnetic-braking rate inside the disc, regulated by non-ideal magnetic diffusion. Using these physical insights, we build a simple 1D semi-analytic model of disc evolution. We show that this 1D model, when coupled to a computationally inexpensive simulation for the evolution of the surrounding pseudodisc, can be used reliably to predict disc evolution in the Class 0/I phase. The predicted long-term evolution of disc size, which saturates at ${\sim}30~{\rm au}$ and eventually shrinks, is consistent with a recent observational survey of Class 0/I discs. Such hierarchical modelling of disc evolution circumvents the computational difficulty of tracing disc evolution through Class 0/I phase with direct, numerically converged simulations.
description: 27 pages, 25 figures; accepted for publication in MNRAS
ASASSN-21co: A detached eclipsing binary with an 11.9 year period
Creators: name: Rowan, D. M.
name: Stanek, K. Z.
name: Way, Z.
name: Kochanek, C. S.
name: Jayasinghe, T.
name: Thompson, Todd A.
name: Barker, H.
name: Hambsch, F. -J.
name: Bohlsen, T.
name: Kafka, Stella
name: Shappee, B. J.
name: Holoien, T. W. -S.
name: Prieto, J. L.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We use ASAS V-band and ASAS-SN g-band observations to model the long-period detached eclipsing binary ASASSN-21co. ASAS observations show an eclipse of depth V ~ 0.6 mag in April of 2009. ASAS-SN g-band observations from March of 2021 show an eclipse of similar duration and depth, suggesting an orbital period of 11.9 years. We combine the g-band observations with additional BVRI photometry taken during the eclipse to model the eclipse using PHOEBE. We find that the system is best described by two M giants with a ratio of secondary radius to primary radius of ~0.61. Optical spectra taken during the eclipse are consistent with at least one component of the binary being an M giant, and we find no temporal changes in the spectral features. The eclipse itself is asymmetric, showing an increase in brightness near mid-eclipse, likely due to rotational variability that is too low amplitude to be observed out-of-eclipse.
description: 4 pages, 1 figure, published in RNAAS
Observing the Inner Shadow of a Black Hole: A Direct View of the Event Horizon
Creators: name: Chael, Andrew
name: Johnson, Michael D.
name: Lupsasca, Alexandru
Publisher: name: arXiv
Year: 2021
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Simulated images of a black hole surrounded by optically thin emission typically display two main features: a central brightness depression and a narrow, bright "photon ring" consisting of strongly lensed images superposed on top of the direct emission. The photon ring closely tracks a theoretical curve on the image plane corresponding to light rays that asymptote to unstably bound photon orbits around the black hole. This critical curve has a size and shape that are purely governed by the Kerr geometry; in contrast, the size, shape, and depth of the observed brightness depression all depend on the details of the emission region. For instance, images of spherical accretion models display a distinctive dark region -- the "black hole shadow" -- that completely fills the photon ring. By contrast, in models of equatorial disks extending to the black hole's event horizon, the darkest region in the image is restricted to a much smaller area -- an inner shadow -- whose edge lies near the direct lensed image of the equatorial horizon. Using both semi-analytic models and general relativistic magnetohydrodynamic (GRMHD) simulations, we demonstrate that the photon ring and inner shadow may be simultaneously visible in submillimeter images of M87*, where magnetically arrested disk (MAD) simulations predict that the emission arises in a thin region near the equatorial plane. We show that the relative size, shape, and centroid of the photon ring and inner shadow can be used to estimate the black hole mass and spin, breaking degeneracies in measurements of these quantities that rely on the photon ring alone. Both features may be accessible to direct observation via high-dynamic-range images with a next-generation Event Horizon Telescope.
description: 24 pages, 16 figures. Submitted to ApJ
Background Modeling in New Physics Searches Using Forward Events at LHC
Creators: name: Pavlunin, Victor
name: Stuart, David
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We present a method to measure dominant Standard Model backgrounds using data containing high rapidity objects in pp collisions at the Large Hadron Collider. The method is developed for analyses of early LHC data when robustness against imperfections of background modeling and detector simulation can be a key to the discovery of new physics at LHC.
description: Intended for PRD
Root-growth of boron nitride nanotubes: Experiments and: Ab initio simulations
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2018
Subjects: physics.chem-ph
cond-mat.mes-hall

description: © 2018 The Royal Society of Chemistry. We have synthesized boron nitride nanotubes (BNNTs) in an arc in the presence of boron and nitrogen species. We find that BNNTs are often attached to large nanoparticles, suggesting that root-growth is a likely mechanism for their formation. Moreover, the tube-end nanoparticles are composed of boron, without transition metals, indicating that transition metals are not necessary for the arc synthesis of BNNTs. To gain further insight into this process we have studied key mechanisms for root growth of BNNTs on the surface of a liquid boron droplet by ab initio molecular dynamics simulations. We find that nitrogen atoms reside predominantly on the droplet surface where they organize to form boron nitride islands below 2400 K. To minimize contact with the liquid particle underneath, the islands assume non-planar configurations that are likely precursors for the thermal nucleation of cap structures. Once formed, the caps are stable and can easily incorporate nitrogen and boron atoms at their base, resulting in further growth. Our simulations support the root-growth mechanism of BNNTs and provide comprehensive evidence of the active role played by liquid boron.
Interfacial ferroelectricity in rhombohedral-stacked bilayer transition metal dichalcogenides
Creators: name: Wang, Xirui
name: Yasuda, Kenji
name: Zhang, Yang
name: Liu, Song
name: Watanabe, Kenji
name: Taniguchi, Takashi
name: Hone, James
name: Fu, Liang
name: Jarillo-Herrero, Pablo
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Van der Waals (vdW) materials have greatly expanded our design space of heterostructures by allowing individual layers to be stacked at non-equilibrium configurations, for example via control of the twist angle. Such heterostructures not only combine characteristics of the individual building blocks, but can also exhibit emergent physical properties absent in the parent compounds through interlayer interactions. Here we report on a new family of emergent, nanometer-thick, semiconductor 2D ferroelectrics, where the individual constituents are well-studied non-ferroelectric monolayer transition metal dichalcogenides (TMDs), namely WSe2, MoSe2, WS2, and MoS2. By stacking two identical monolayer TMDs in parallel, we obtain electrically switchable rhombohedral-stacking configurations, with out-of-plane polarization that is flipped by in-plane sliding motion. Fabricating nearly-parallel stacked bilayers enables the visualization of moiré ferroelectric domains as well as electric-field-induced domain wall motion with piezoelectric force microscopy (PFM). Furthermore, by using a nearby graphene electronic sensor in a ferroelectric field transistor geometry, we quantify the ferroelectric built-in interlayer potential, in good agreement with first-principles calculations. The novel semiconducting ferroelectric properties of these four new TMDs opens up the possibility of studying the interplay between ferroelectricity and their rich electric and optical properties.
description: 16 pages, 4 figures
Low-mass dark matter search with the DarkSide-50 experiment
Creators: name: (:Unkn) Unknown
Publisher: name: My University
Year: 2018
Subjects: DarkSide Collaboration

description: © 2018 American Physical Society. We present the results of a search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 20 GeV=c2 using a target of low-radioactivity argon with a 6786.0 kg d exposure. The data were obtained using the DarkSide-50 apparatus at Laboratori Nazionali del Gran Sasso. The analysis is based on the ionization signal, for which the DarkSide-50 time projection chamber is fully efficient at 0.1 keVee. The observed rate in the detector at 0.5 keVee is about 1.5 event=keVee=kg=d and is almost entirely accounted for by known background sources. We obtain a 90% C.L. exclusion limit above 1.8 GeV=c2 for the spin-independent cross section of dark matter WIMPs on nucleons, extending the exclusion region for dark matter below previous limits in the range 1.8-6 GeV=c2.
New synthetic methods using β-keto esters and some useful applications in natural products syntheses
Creators: name: Sum, Fuk-Wah
Publisher: name: University of British Columbia
Year: 2010

description: Results from studies on the cyclization of β-keto ester derivatives are presented. Electrophile- and acid-initiated cyclization of unsaturated β-keto esters, and the cyclization of epoxy β-keto esters provide interesting routes to some carbocyclic and heterocyclic compounds. Factors determining the predominance of C- or O-cyclization are discussed. The effect of olefin and epoxide substitution patterns on the reactivity and mode of cyclization was briefly investigated. A novel stereospecific synthesis of substituted alkenes from β-keto esters was achieved, along with the extension of this method to β-diketones (equation I) . Stereoselective synthesis of the E- and Z-enol phosphates of β-dicarbonyl compounds was developed. These enol phosphates reacted stereospecifically with lithium dialkylcuprates to give α, β-unsaturated carbonyl compounds. An efficient one-pot preparation of β, β-disubstituted- α, β-unsaturated esters from methyl acetoacetate based on these findings and the dianion chemistry of β-keto esters is also illustrated. The effect of a β-phosphoryloxy substituent on the reduction potential of an α, β-ethylenic carbonyl compound was estimated to be + 0.1 V. A plausible mechanism for the reaction between 1,3-dicarbonyl enol phosphates and lithium dialkylcuprates was proposed. A convenient route to the cyclohexene derivative 248 is described. This compound represents a useful synthetic substrate for the synthesis of several classes of natural products. The facile introduction of an isoprene unit, using methyl acetoacetate, in a stereoselective manner as indicated by equation ii is also demonstrated. The syntheses of three natural products, viz., Latia luciferin (328), (E, E)-10-hydroxy-3,7-dimethyldeca-2,6-dienoic acid (335) and mokupalide (347) are presented, which illustrate some useful applications of the new synthetic methods developed. While the syntheses of 328 and 335 show improvements over the previous preparations of these compounds, the synthesis of mokupalide (347) represents the first synthetic approach to this compound. [See thesis for Chemical Diagram]
Influences of degree inhomogeneity on average path length and random walks in disassortative scale-free networks
Creators: name: Zhang, Zhongzhi
name: Zhang, Yichao
name: Zhou, Shuigeng
name: Yin, Ming
name: Guan, Jihong
Publisher: name: arXiv
Year: 2008
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Various real-life networks exhibit degree correlations and heterogeneous structure, with the latter being characterized by power-law degree distribution $P(k)\sim k^{-γ}$, where the degree exponent $γ$ describes the extent of heterogeneity. In this paper, we study analytically the average path length (APL) of and random walks (RWs) on a family of deterministic networks, recursive scale-free trees (RSFTs), with negative degree correlations and various $γ\in (2,1+\frac{\ln 3}{\ln 2}]$, with an aim to explore the impacts of structure heterogeneity on APL and RWs. We show that the degree exponent $γ$ has no effect on APL $d$ of RSFTs: In the full range of $γ$, $d$ behaves as a logarithmic scaling with the number of network nodes $N$ (i.e. $d \sim \ln N$), which is in sharp contrast to the well-known double logarithmic scaling ($d \sim \ln \ln N$) previously obtained for uncorrelated scale-free networks with $2 \leq γ<3$. In addition, we present that some scaling efficiency exponents of random walks are reliant on degree exponent $γ$.
description: The definitive verion published in Journal of Mathematical Physics
Pre-reionization Fossils, Ultra-faint Dwarfs and the Missing Galactic Satellite Problem
Creators: name: Bovill, Mia S.
name: Ricotti, Massimo
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We argue that, at least a fraction of the newly discovered population of ultra-faint dwarf spheroidal galaxies in the Local Group constitute the fossil relic of a once ubiquitous population of dwarf galaxies formed before reionization with circular velocities smaller than $v_{c}^{cr} \sim 20$ km/s. We present several arguments in support of this model. The number of luminous Milky Way satellites inferred from observations is larger than the estimated number of dark halos in the Galaxy that have, or had in the past, circular velocity $>v_{c}^{cr}$, as predicted by the "Via Lactea" simulation. This implies that some ultra-faint dwarfs are fossils. However, this argument is weakened by recent results from the "Aquarius" simulations showing that the number of Galactic dark matter satellites is 2.5 larger than previously believed. Secondly, the existence of a population of ultra-faint dwarfs was predicted by cosmological simulations in which star formation in the first minihalos is reduced -- but not suppressed -- by radiative feedback. Here, we show the statistical properties of the fossil galaxies in those simulations are consistent with observations of the new dwarf population and with the number and radial distribution of Milky Way satellites as a function of their luminosity. Finally, the observed Galactocentric distribution of dwarfs is consistent with a fraction of dSphs being fossils. To make our case more compelling, future work should determine whether stellar chemical abundances of simulated "fossils" can reproduce observations and whether the tidal scenarios for the formation of Local Group dwarf spheroidals are equally consistent with all available observations.
description: ApJ accepted version, in press, 8 figure, 3 tables
Absence of Anomalous Tunneling of Bogoliubov Excitations for Arbitrary Potential Barrier under the Critical Condensate Current
Creators: name: Takahashi, Daisuke
name: Kato, Yusuke
Publisher: name: arXiv
Year: 2008
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We derive the exact solution of low energy limit of Bogoliubov equations for excitations of Bose-Einstein condensate in the presence of arbitrary potential barrier and maximum current of condensate. Using this solution, we give the explicit expression for the transmission coefficient against the potential barrier, which shows partial transmission in the low energy limit. The wavefunctions of excitations in the low energy limit do not coincide with that of the condensate. The absence of the perfect transmission in the critical current state originates from local enhancement of density fluctuations around the potential barrier.
description: 4 pages, 1 figure
Physics-Informed Deep Learning Characterizes Morphodynamics of Asian Soybean Rust Disease
Creators: name: Cavanagh, Henry
name: Mosbach, Andreas
name: Scalliet, Gabriel
name: Lind, Rob
name: Endres, Robert G.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: Medicines and agricultural biocides are often discovered using large phenotypic screens across hundreds of compounds, where visible effects of whole organisms are compared to gauge efficacy and possible modes of action. However, such analysis is often limited to human-defined and static features. Here, we introduce a novel framework that can characterize shape changes (morphodynamics) for cell-drug interactions directly from images, and use it to interpret perturbed development of Phakopsora pachyrhizi, the Asian soybean rust crop pathogen. We describe population development over a 2D space of shapes (morphospace) using two models with condition-dependent parameters: a top-down Fokker-Planck model of diffusive development over Waddington-type landscapes, and a bottom-up model of tip growth. We discover a variety of landscapes, describing phenotype transitions during growth, and identify possible perturbations in the tip growth machinery that cause this variation. This demonstrates a widely-applicable integration of unsupervised learning and biophysical modeling.