cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Towards the Biconjugate of Bivariate Piecewise Quadratic Functions
Creators: name: Kumar, Deepak
name: Lucet, Yves
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics
subject: 90C26

description: Computing the closed convex envelope or biconjugate is the core operation that bridges the domain of nonconvex with convex analysis. We focus here on computing the conjugate of a bivariate piecewise quadratic function defined over a polytope. First, we compute the convex envelope of each piece, which is characterized by a polyhedral subdivision such that over each member of the subdivision, it has a rational form (square of a linear function over a linear function). Then we compute the conjugate of all such rational functions. It is observed that the conjugate has a parabolic subdivision such that over each member of its subdivision, it has a fractional form (linear function over square root of a linear function). This computation of the conjugate is performed with a worst-case linear time complexity algorithm. Our results are an important step toward computing the conjugate of a piecewise quadratic function, and further in obtaining explicit formulas for the convex envelope of piecewise rational functions.
description: 11 pages, 3 figures
Dwarf Spheroidals in MOND
Creators: name: Angus, Garry W.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We take the line of sight velocity dispersions as functions of radius for 8 Milky Way dwarf spheroidal galaxies and use Jeans analysis to calculate the mass-to-light ratios (M/L) in Modified Newtonian Dynamics (MOND). Using the latest structural parameters, distances and variable velocity anisotropy, we find 6/8 dwarfs have sensible M/L using only the stellar populations. Sextans and Draco, however, have M/L=9.2_{-3.0}^{+5.3} and 43.9_{-19.3}^{+29.0} respectively, which poses a problem. Apart from the need for Sextans' integrated magnitude to be reviewed, we propose tidal effects intrinsic to MOND, testable with numerical simulations, but fully orbit dependant, which are disrupting Draco. The creation of the Magellanic Stream is also re-addressed in MOND, the scenario being the stream is ram pressure stripped from the SMC as it crosses the LMC.
description: 9 pages, 3 figures, 1 table. Accepted for publication in MNRAS
The star catalogue of Wilhelm IV, Landgraf von Hessen-Kassel: Accuracy of the catalogue and of the measurements
Creators: name: Verbunt, Frank
name: Schrimpf, Andreas
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: We analyse a manuscript star catalogue by Wilhem IV, Landgraf von Hessen-Kassel, from 1586. From measurements of altitudes and of angles between stars, given in the catalogue, we find that the measurement accuracy averages 26 arcsec for eight fundamental stars, compared to 49 arcsec of the measurements by Brahe. The computation in converting altitudes to declinations and angles between stars to celestial position is very accurate, with errors negligible with respect to the measurement errors. Due to an offset in the position of the vernal equinox the positional error of the catalogue is slightly worse than that of Brahe's catalogue, but when correction is made for the offset -- which was known to 17th century astronomers -- the catalogue is more accurate than that of Brahe by a factor two. We provide machine-readable Tables of the catalogue.
description: 12 pages, 8 figures, 11 tables. Accepted for publication in Astronomy and Astrophysics. Machine-readable tables at CDS
Measurement of the fraction of t-tbar production via gluon-gluon fusion in p-pbar collisions at sqrt(s)=1.96 TeV
Creators: name: CDF Collaboration
name: Abulencia, A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: We present a measurement of the ratio of t-tbar production cross section via gluon-gluon fusion to the total t-tbar production cross section in p-pbar collisions at sqrt{s}=1.96 TeV at the Tevatron. Using a data sample with an integrated luminosity of 955/pb recorded by the CDF II detector at Fermilab, we select events based on the t-tbar decay to lepton+jets. Using an artificial neural network technique we discriminate between t-tbar events produced via q-qbar annihilation and gluon-gluon fusion, and find Cf=(gg->ttbar)/(pp->ttbar)<0.33 at the 68% confidence level. This result is combined with a previous measurement to obtain the most precise measurement of this quantity, Cf=0.07+0.15-0.07.
description: submitted to Phys. Rev. D
Libro IV. Verso un universo uniforme: comete, extra-terrestri, elementi, in M. A. Granada e D. Tessicini (a cura di), Giordano Bruno, De immenso. Letture critiche, Pisa-Roma, Fabrizio Serra Editore, 2020, pp. 123-145
Creators: name: Del Prete, Antonella
Publisher: name: Zenodo
Year: 2020

description: bozze
Cohomological rigidity of real Bott manifolds
Creators: name: Kamishima, Yoshinobu
name: Masuda, Mikiya
Publisher: name: arXiv
Year: 2008
Subjects: subject: Algebraic Topology (math.AT)
subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 57R91, 53C25, 14M25

description: A real Bott manifold is the total space of iterated RP^1 bundles starting with a point, where each RP^1 bundle is projectivization of a Whitney sum of two real line bundles. We prove that two real Bott manifolds are diffeomorphic if their cohomology rings with Z/2 coefficients are isomorphic. A real Bott manifold is a real toric manifold and admits a flat riemannian metric invariant under the natural action of an elementary abelian 2-group. We also prove that the converse is true, namely a real toric manifold which admits a flat riemannian metric invariant under the action of an elementary abelian 2-group is a real Bott manifold.
description: 22 pages
Occurence (sic) of a pink color in cooked turkey breast
Creators: name: Girard, Benoît
Publisher: name: University of British Columbia
Year: 2010

description: A peculiar problem involving cooked turkey products is the appearance of a pink color which consumers often associate with undercooking. Measurements of redness over a period of 4 days of storage were taken on 2 mm thick breast slices from 12 or 18 week old turkeys cooked at selected temperatures of 65, 75, 85 and 95 °C. An analysis of variance indicated that, unlike the age effect, temperature, storage time and their interaction were statistically significant at p<0.01 level. Proper cooking, achieved when an end-point temperature of 85 °C was reached, did not only produce a white to golden-brown color. A tinge of redness was detected by Hunter aL measurement immediately after cooking and disappeared after 3 to 4 days. A simple method developed for the evaluation of pigments in situ, using transmission spectrophotometry, revealed that the residual pink color could be caused by cytochrome c. Visible spectra and electrophoretograms of extracts from cooked breast slices supported the involvement of this pigment. The concentration of cytochrome c in these extracts was 7.9x10⁻² and 5.4x10⁻² mg/g tissue in samples from 12 and 18 week old birds respectively. However the total hemoprotein content in these same breast samples increased from 0.60 to 0.77 mg/g tissue. The method for the evaluation of pigments in situ also was modified in order to investigate the effect of air contact on color immediately after cooking. Additional absorption bands were present when meat slices were kept under anaerobic conditions. The rapid disappearance of these peaks once the meat surface was exposed to air indicated the susceptibility of other hemochromes to oxidation and therefore underlined their relative unimportance in the pinkening phenomenon. Since the above hemoproteins and hemochromes involved in the pinkening phenomenon need to be in a reduced form to give the obtained difference spectra, procedures using ultrafiltration and chromatography were established to search for reducing compounds. The reducing capacity of 1 mL fraction during the first minute of contact with a solution of hemoprotein was called hemoprotein initial reducing activity (IRA). Two groups, one above (higher molecular weight compounds or HMW) and one below (lower molecular weight compounds or LMW) 3000 daltons, were separated. The LMW had a low IRA for both myoglobin and cytochrome c. On the other hand, HMW were produced after heating at 85 °C for 10 min and strongly reduced only cytochrome c. It is postulated that the isolated material may be Maillard reaction products.
Is pregnancy loss (that) disenfranchised? Evidence from a vignette study
Creators: name: Buyukcan-Tetik, Asuman
name: Topal, Mustafa Anil
name: Ergun, Turan Deniz
name: Bagci, Sabahat Cigdem
name: Kizilirmak, Kubra
name: Boelen, Paul A.
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Medicine
subject: Genetics
subject: FOS: Biological sciences
subject: Neuroscience
subject: Science Policy
subject: Mental Health

description: Background: Perceiving that society disregards grief after pregnancy loss (disenfranchised grief) elevates bereaved parents’ psychological burden. Objective: In this research, we aimed to compare the disenfranchisement of pregnancy loss with four other loss types considering the bereaved’s gender. Method: We collected data from Turkish participants (N = 1,280) using a 5 (loss type) x 2 (gender) between-subjects design with randomly assigned vignettes. Participants reported their expected grief and behavioural tendencies toward the bereaved. We conducted MANOVA and ANOVA analyses. Results: Results revealed that participants expected higher grief for pregnancy loss than two other disenfranchised grief types (former colleague’s death, grandfather’s diagnosis with Alzheimer’s). Expected grief for pregnancy loss was higher than or similar to the level for the best friend’s loss across examinations but lower than the level for the one-year-old child’s loss. Behaviour tendencies were alike across vignettes, and their results did not paint a coherent picture. Findings did not differ by the bereaved’s gender. Conclusion: Pregnancy loss might be less disenfranchised than bereaved parents perceive it, and parents’ perceptions could be targeted in therapeutic interventions. We investigated whether pregnancy loss is more disenfranchised by society than four other loss types considering the bereaved’s gender.We collected data from a large sample in Turkey.Pregnancy loss might be less disenfranchised than argued in the literature. We investigated whether pregnancy loss is more disenfranchised by society than four other loss types considering the bereaved’s gender. We collected data from a large sample in Turkey. Pregnancy loss might be less disenfranchised than argued in the literature.
Fluttuazioni cartesiane: Van Velthuysen e Spinoza, in L. Bianchi, A. Del Prete, G. Paganini (a cura di), Cartesianismi, scetticismi, filosofia moderna. Studi per Carlo Borghero, a cura di, Firenze, Le Lettere, 2019, pp. 141-158
Creators: name: Del Prete, Antonella
Publisher: name: Zenodo
Year: 2019

description: pdf editoriale
The effects of spatially distributed ionisation sources on the temperature structure of HII region
Creators: name: Ercolano, B.
name: Bastian, N.
name: Stasinska, G.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Spatially resolved studies of star forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star clusters. We try to isolate the effects of multiple non-centrally located stars on the temperature and ionisation structure of HII regions, via the construction of 3D photoionisation models using the 3D Monte Carlo photoionisation code MOCASSIN. We find that the true temperature fluctuations due to the stellar distribution (as opposed to the large-scale temperature gradients due to other gas properties) are small in all cases and not a significant cause of error in metallicity studies. Strong emission lines from HII regions are often used to study the metallicity of star-forming regions. We compare integrated emission line spectra from our models and quantify any systematic errors caused by the simplifying assumption of a single, central location for all ionising sources. We find that the dependence of the metallicity indicators on the ionisation parameter causes a clear bias, due to the fact that models with a fully distributed configuration of stars always display lower ionisation parameters than their fully concentrated counterparts. The errors found imply that the geometrical distribution of ionisation sources may partly account for the large scatter in metallicities derived using model-calibrated empirical methods.
description: 13 pages, 6 figures, Accepted by MNRAS
Nuclear Electric Dipole Moment of 3He
Creators: name: Stetcu, I.
name: Liu, C. -P.
name: Friar, J. L.
name: Hayes, A. C.
name: Navratil, P.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: A permanent electric dipole moment (EDM) of a physical system requires time-reversal (T) and parity (P) violation. Experimental programs are currently pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of fundamental theoretical interest. Here we calculate the magnitude of the PT-violating EDM of 3He and the expected sensitivity of such a measurement to the underlying PT-violating interactions. Assuming that the coupling constants are of comparable magnitude for pi-, rho-, and omega-exchanges, we find that the pion-exchange contribution dominates. Our results suggest that a measurement of the 3He EDM is complementary to the planned neutron and deuteron experiments, and could provide a powerful constraint for the theoretical models of the pion-nucleon PT-violating interaction.
description: 6 pages, 1 figure
Analytic normal mode frequencies for N identical particles: The microscopic dynamics underlying the emergence and stability of excitation gaps from BCS to unitarity
Creators: name: Watson, D. K.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The frequencies of the analytic normal modes for N identical particles are studied as a function of system parameters from the weakly interacting BCS regime to the strongly interacting unitary regime. The normal modes were obtained previously from a first-order L=0 group theoretic solution of a three-dimensional Hamiltonian with a general two-body interaction for confined, identical particles. In a precursor to this study, the collective behavior of these normal modes was investigated as a function of N from few-body systems to many-body systems analyzing the contribution of individual particles to the collective macroscopic motions. A specific case, the Hamiltonian for Fermi gases in the unitary regime was studied in more detail. This regime is known to support collective behavior in the form of superfluidity and has previously been successfully described using normal modes. Two phenomena that could sustain the emergence and stability of superfluid behavior were revealed, including the behavior of the normal mode frequencies as N increases. In this paper, I focus on a more detailed analysis of these analytic frequencies, extending my investigation to include Hamiltonians with a range of interparticle interaction strengths from the BCS regime to the unitary regime and analyzing the microscopic dynamics that lead to large gaps at unitarity. The results of the current study suggest that in regimes where higher-order effects are small, normal modes an be used to describe the physics of superfluidity from the weakly interacting BCS regime with the emergence of small excitation gaps to unitarity with its large gaps, and can offer insight into a possible microscopic understanding of the behavior at unitarity. This approach could thus offer an alternative to the two-body pairing models commonly used to describe superfluidity along this transition.
description: 23 pages including 7 Appendices and 16 figures
IPSL-EPOC decadal predic;on system: An update from the trenches
Creators: name: Mignot, Juliette
Publisher: name: Zenodo
Year: 2019

description: Presentation held at the EU modelling cluster workshop in Bergen, 5-7 June 2019.

Outline:

1. The IPSL-CM6 new decadal prediction system: Status and Potential predictability

2. The IPSL-CM5 decadal predic6on system: Windows of opportunity and Towards a new methodology for debiasing hindcasts
A Massive Core in Jupiter Predicted From First-Principles Simulations
Creators: name: Militzer, B.
name: Hubbard, W. B.
name: Vorberger, J.
name: Tamblyn, I.
name: Bonev, S. A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Hydrogen-helium mixtures at conditions of Jupiter's interior are studied with first-principles computer simulations. The resulting equation of state (EOS) implies that Jupiter possesses a central core of 14-18 Earth masses of heavier elements, a result that supports core accretion as standard model for the formation of hydrogen-rich giant planets. Our nominal model has about 2 Earth masses of planetary ices in the H-He-rich mantle, a result that is, within modeling errors, consistent with abundances measured by the 1995 Galileo Entry Probe mission (equivalent to about 5 Earth masses of planetary ices when extrapolated to the mantle), suggesting that the composition found by the probe may be representative of the entire planet. Interior models derived from this first-principles EOS do not give a match to Jupiter's gravity moment J4 unless one invokes interior differential rotation, implying that jovian interior dynamics has an observable effect on the measured gravity field.
description: 6 pages, 4 figures, 1 table
Che cosa ci insegna l'aristotelismo padovano? Immortalità dell'anima, empietà e problemi di metodo storico, in S. Bassi (a cura di), Costellazioni concettuali tra Cinquecento e Settecento. Filosofia, religione e politica, Firenze, Olschki, 2019, pp. 79-96
Creators: name: Del Prete, Antonella
Publisher: name: Zenodo
Year: 2019

description: Bozze
Development of New Methods for the Synthesis of N-Heteroarenes from Nitroarenes and Anilines
Creators: name: Zhu, Haoran
Publisher: name: University of Illinois at Chicago
Year: 2024

description: This thesis focuses on unlocking the reactivity embedded in nitroarenes and anilines to construct N-heterocycles. The first part of this work shows that exposure of nitrostilbenes to sodium tert-butoxide was found to produce N-hydroxyindoles at room temperature without an additive. Changing the counterion to potassium changed the reaction outcome to yield solely oxindoles through an unprecedented dioxygen-transfer reaction followed by a 1,2-phenyl migration. Mechanistic experiments using EPR spectroscopy, crown ether and isotopically labeled substrates established that these reactions proceed via radical intermediates and suggest that counterion coordination controls whether an oxindole or N-hydroxyindole product is formed.
The next part of this work develops two novel electrochemical cyclization reactions for the synthesis of quinoline N-oxide and 3H-indoles. We found that the nitro radical anion from nitroarenes and nitrenoid or nitrene intermediates from anilines could be generated through SET process directly from electricity. The scopes and potential mechanisms are also investigated in this part.
The last section in this thesis is exploring the application of a formerly developed Cu-catalyzed cross-coupling reactions to construct diarylamines. This reaction is optimized in a large-scale synthesis to show the robustness of this reaction system.
Time-Gated Photon Counting Receivers for Optical Wireless Communication
Creators: name: Huang, Shenjie
name: Safari, Majid
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: Photon counting detectors such as single-photon avalanche diode (SPAD) arrays are commonly considered for reliable optical wireless communication at power limited regimes. However, SPAD-based receivers suffer from significant dead time induced intersymbol interference (ISI) especially when the incident photon rate is relatively high and the dead time is comparable or even larger than the symbol duration, i.e., sub-dead-time regime. In this work, we propose a novel time-gated SPAD receiver to mitigate such ISI effects and improve the communication performance. When operated in the gated mode, the SPAD can be activated and deactivated in well-defined time intervals. We investigate the statistics of the detected photon count for the proposed time-gated SPAD receiver. It is demonstrated that the gate-ON time interval can be optimized to achieve the best bit error rate (BER) performance. Our extensive performance analysis illustrates the superiority of the time-gated SPAD receiver over the traditional free-running receiver in terms of the BER performance and the tolerance to background light.
Coherent defect-assisted multiphonon intraband carrier relaxation in semiconductor quantum dots
Creators: name: Poddubny, A. N.
name: Goupalov, S. V.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: new defect-assisted mechanism of multiphonon intraband carrier relaxation in semiconductor quantum dots, where the carrier is found in a coherent superposition of the initial, final, and defect states, is proposed. It is shown that this mechanism is capable of explaining the observed trends in temperature dependences of the intraband relaxation rates for PbSe and CdSe colloidal nanocrystal quantum dots.
description: 7 pages, 3 figures, submitted to Phys.Rev. B
Financial viability of offshore wind on the Texas Gulf Coast
Creators: name: Hoffman, Cody Scott
Publisher: name: The University of Texas at Austin
Year: 2019
Subjects: Wind
Offshore wind
Renewable energy
Coastal wind
Financial analysis

description: Offshore wind is already a significant component of the electricity generation mix in Europe, and improvements in technology and cost are enabling increased offshore wind penetration in new markets around the world. Thus far, the US has struggled to materially participate in this industry, with only a single 30 MW offshore project in operation. Navigating a complicated regulatory framework, the lack of a coherent national policy, and facing local opposition, the industry has experienced some spectacular failures in recent years. However, the US now has an opportunity to take advantage of the lessons learned from years of (primarily) European development and combine them with excellent offshore wind resources close to transmission-constrained load centers. By far the leader of the US onshore wind industry, and with a long history of offshore oil and gas development, Texas has some major advantages when it comes to offshore wind. Wind resources in the Gulf of Mexico are more than adequate for economic production. With shallow depths and relatively calm seas, the Texas Gulf Coast is also well suited to offshore wind construction. These factors, coupled with a pro-development state regulatory scheme and extended jurisdiction over submerged lands, suggest that Texas is an ideal candidate for offshore wind development. With no currently active projects in the pipeline, this thesis examines the economic viability of offshore wind development on the Texas Gulf Coast at the project level. Using an ideal location and cost data from National Renewable Energy Laboratory (NREL), the Energy Information Administration (EIA), and industry sources, a hypothetical “test project” was developed and evaluated against three cost estimate cases and ten regulatory scenarios. These inputs were fed into a Discounted Cash Flow model to determine potential competitiveness in the Power Purchase Agreement (PPA) market in the ERCOT region. Results indicate that without significant cost reductions or major changes to either market conditions or federal/state incentive schemes, Texas Gulf Coast offshore wind cannot compete with other forms of onshore renewable generation. With ever-decreasing costs, it is not impossible that offshore wind could become viable at some point in the future, but given current conditions, it is not likely that any projects are on the near-term horizon.
The effect of oxidized dietary lipid and vitamin E on growth and immunocompetence of coho salmon (Oncorhynchus kisutch)
Creators: name: Forster, Ian
Publisher: name: University of British Columbia
Year: 2010

description: Highly unsaturated marine lipids are common ingredients in salmon diets, and they are prone to oxidative change. The present study was undertaken to examine the growth and health of coho salmon (Oncorhynchus kisutch) fed diets containing herring oil autoxidized to different degrees. The efficacy of dietary vitamin E in ameliorating any adverse effect on performance was investigated. Herring oil was oxidized to one of two levels (relative to a control) by aeration and mild heating (40 °C). Peroxide values and iodine numbers were recorded to monitor the extent of autoxidation. Depletion of dietary linolenic acid series fatty acids (n3FA), and the labile vitamins A, C, and E, provided further evidence of the progress of lipid oxidation. The mean initial body weight was 5.1 g/fish, and growth (weight and length) was measured at 3 or 6 week intervals for 28 weeks. Experimental diets contained 16.8% lipid, primarily as herring oil. One diet was made with corn oil replacing herring oil, and another contained a combination of low and highly oxidized oil. Vitamin E (as dl-ɑ-tocopheryl acetate) was added at either 30 IU/kg dry diet or 1000 IU/kg dry diet. At 23 weeks, 1/3 of the fish were vaccinated against vibriosis. At 28 weeks the fish were twice challenged with live Vibrio sp. Immunocompetence was estimated by mortality and by plasma agglutination. The inclusion of autoxidized herring oil reduced the nutritive value of the diets. The poorer growth and feed efficiency of fish fed diets containing oxidized oils appears to have resulted from a combination of appetite suppression and nutrient deficiency. The relative importance of these factors in influencing growth and feed efficiency depended upon the extent of the oxidation, with appetite suppression being most apparent in fish fed diets containing moderately oxidized oil. Dietary supplementation with a high level of vitamin E had no ameliorating effect on growth or feed efficiency. Health and immunocompetence were not impaired by the presence of oxidized dietary lipid, or improved by the addition of vitamin E.
Combining data assimilation and machine learning to emulate a dynamical model from sparse and noisy observations
Creators: name: Brajard, Julien
name: Carrassi, Alberto
name: Bocquet, Marc
name: Bertino, Laurent
Publisher: name: Zenodo
Year: 2019

description: Is it possible to emulate a numerical model from noisy and sparse observations? How realistic and skilful can it be? Recent progress in machine learning has shown how to forecast a model from observations. We will show that by leveraging on data assimilation techniques, it is possible to produce realistic and skilful surrogate models of the underlying dynamics given sparse and noisy observations.  The approach is tested with several chaotic systems. The surrogate model shows both forecast skills and abilities to reproduce the “climate” (i.e. spectral properties and statistical moments) of the underlying dynamical model on long-term simulations.
Exploring the tilted accretion disc of AQ Men with TESS
Creators: name: Ilkiewicz, Krystian
name: Scaringi, Simone
name: Court, James M. C.
name: Maccarone, Thomas J.
name: Altamirano, Diego
name: Bradshaw, Corey W.
name: Degenaar, Nathalie
name: Fratta, Matteo
name: Littlefield, Colin
name: Shahbaz, Tariq
name: Wijnands, Rudy
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: AQ Men is a nova-like variable which is presumed to have a tilted, precessing accretion disc. Grazing eclipses in this system have been speculated to be useful in exploring the geometry of its accretion disc. In this work we analysed TESS observations of AQ Men, which provide the best light curve of this object thus far. We show that the depths of the eclipses are changing with the orientation of the accretion disc, which means that they can serve as a direct test of the tilted accretion disc models. The precession period of the accretion disc is increasing during the TESS observations. However, it is still shorter than the period determined in the previous studies. The amplitude of the variability related to the precession of the accretion disc varies, and so does the shape of this variability. Moreover, we have detected a positive superhump that was previously unseen in AQ Men. Interestingly, the positive superhump has a strongly non-sinusoidal shape, which is not expected for a nova-like variable.
description: 11 pages, 11 figures, accepted for publication in MNRAS
Branching ratios and CP asymmetries of $B \to K η^{(\prime)}$ decays in the pQCD approach
Creators: name: Xiao, Zhen-Jun
name: Zhang, Zhi-Qing
name: Liu, Xin
name: Guo, Li-Bo
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We calculate the branching ratios and CP violating asymmetries of the four $B \to K \etap$ decays in the perturbative QCD (pQCD) factorization approach. Besides the full leading order contributions, the partial next-to-leading order (NLO) contributions from the QCD vertex corrections, the quark loops, and the chromo-magnetic penguins are also taken into account. The NLO pQCD predictions for the CP-averaged branching ratios are $Br(B^+ \to K^+ η) \approx 3.2 \times 10^{-6}$, $Br(B^\pm \to K^\pm \etar) \approx 51.0 \times 10^{-6}$, $Br(B^0 \to K^0 η) \approx 2.1 \times 10^{-6}$, and $Br(B^0 \to K^0 \etar) \approx 50.3 \times 10^{-6}$. The NLO contributions can provide a 70% enhancement to the LO $Br(B \to K \etar)$, but a 30% reduction to the LO $Br(B \to K η)$, which play the key role in understanding the observed pattern of branching ratios. The NLO pQCD predictions for the CP-violating asymmetries, such as $\acp^{dir} (K^0_S \etar) \sim 2.3% $ and $\acp^{mix}(K^0_S \etar)\sim 63%$, agree very well with currently available data. This means that the deviation $ΔS=\acp^{mix}(K^0_S \etar) - \sin{2β}$ in pQCD approach is also very small.
description: 31 pages, 11 ps/eps figures, typos corrected. A little modification
Vibrational Coherences in Nano-Elastic Tunneling
Creators: name: Hübener, Hannes
name: Brandes, Tobias
Publisher: name: arXiv
Year: 2007
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Charging a nano-scale oscillator by single electron tunneling leads to an effective double-well potential due to image charges. We combine exact numerical diagonalizations with generalized Master equations and show that the resulting quantum tunneling of the mechanical degree of freedom can be visualized in the electronic current noise spectrum.
description: 4 pages, 4 figures
The Nature of the Hard-X-Ray Emitting Symbiotic Star RT Cru
Creators: name: Luna, G. J. M.
name: Sokoloski, J. L.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We describe Chandra High-Energy Transmission Grating Spectrometer observations of RT Cru, the first of a new sub-class of symbiotic stars that appear to contain white dwarfs (WDs) capable of producing hard X-ray emission out to greater than 50 keV. The production of such hard X-ray emission from the objects in this sub-class (which also includes CD -57 3057, T CrB, and CH Cyg) challenges our understanding of accreting WDs. We find that the 0.3 -- 8.0 keV X-ray spectrum of RT Cru emanates from an isobaric cooling flow, as in the optically thin accretion-disk boundary layers of some dwarf novae. The parameters of the spectral fit confirm that the compact accretor is a WD, and they are consistent with the WD being massive. We detect rapid, stochastic variability from the X-ray emission below 4 keV. The combination of flickering variability and a cooling-flow spectrum indicates that RT Cru is likely powered by accretion through a disk. Whereas the cataclysmic variable stars with the hardest X-ray emission are typically magnetic accretors with X-ray flux modulated at the WD spin period, we find that the X-ray emission from RT Cru is not pulsed. RT Cru therefore shows no evidence for magnetically channeled accretion, consistent with our interpretation that the Chandra spectrum arises from an accretion-disk boundary layer.
description: 3 figures, accepted for publication in ApJ
The Prince of Cartesian Philosophers, in S. Nadler, T. M. Schmaltz, D. Antoine-Mahut, (dir.), Oxford Handbook of Descartes and Cartesianism, Oxford, Oxford University Press, 2019, pp. 374-387
Creators: name: Del Prete, Antonella
Publisher: name: Zenodo
Year: 2019

description: Bozze
Comparison of Jupiter Interior Models Derived from First-Principles Simulations
Creators: name: Militzer, B.
name: Hubbard, W. B.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recently two groups used first-principles computer simulations to model Jupiter's interior. While both studies relied on the same simulation technique, density functional molecular dynamics, the groups derived very different conclusions. In particular estimates for the size of Jupiter's core and the metallicity of its hydrogen-helium mantle differed substantially. In this paper, we discuss the differences of the approaches and give an explanation for the differing conclusions.
description: 5 pages, no figures
Tunneling of a composite particle: Effects of intrinsic structure
Creators: name: Bertulani, C. A.
name: Flambaum, V. V.
name: Zelevinsky, V. G.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We consider simple models of tunneling of an object with intrinsic degrees of freedom. This important problem was not extensively studied until now, in spite of numerous applications in various areas of physics and astrophysics. We show possibilities of enhancement for the probability of tunneling due to the presence of intrinsic degrees of freedom split by weak external fields or by polarizability of the slow composite object.
description: 6 pages, 3 figures, version to be published in Journal of Physics G
Subaru Telescope -- History, Active/Adaptive Optics, Instruments, and Scientific Achievements
Creators: name: Iye, Masanori
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The Subaru Telescope is an 8.2 m optical/infrared telescope constructed during 1991--1999 and has been operational since 2000 on the summit area of Maunakea, Hawaii, by the National Astronomical Observatory of Japan (NAOJ). This paper reviews the history, key engineering issues, and selected scientific achievements of the Subaru Telescope. The active optics for a thin primary mirror was the design backbone of the telescope to deliver a high-imaging performance. Adaptive optics with a laser-facility to generate an artificial guide-star improved the telescope vision to its diffraction limit by cancelling any atmospheric turbulence effect in real time. Various observational instruments, especially the wide-field camera, have enabled unique observational studies. Selected scientific topics include studies on cosmic reionization, weak/strong gravitational lensing, cosmological parameters, primordial black holes, the dynamical/chemical evolution/interactions of galaxies, neutron star mergers, supernovae, exoplanets, proto-planetary disks, and outliers of the solar system. The last described are operational statistics, plans and a note concerning the culture-and-science issues in Hawaii.
description: 35 pages, 46 figures, 3 table, soon to be published in the Proceedings of the Japan Academy, Series B
Finding the symmetry group of an LP with equality constraints and its application to classifying orthogonal arrays
Creators: name: Geyer, Andrew J.
name: Bulutoglu, Dursun A.
name: Ryan, Kenneth J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Optimization and Control (math.OC)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 90C05 90C10 68R10

description: For a given linear program (LP) a permutation of its variables that sends feasible points to feasible points and preserves the objective function value of each of its feasible points is a symmetry of the LP. The set of all symmetries of an LP, denoted by $G^{\rm LP}$, is the symmetry group of the LP. Margot [F. Margot, 50 Years of Integer Programming 1958-2008 (2010), 647-686] described a method for computing a subgroup of the symmetry group $G^{\rm LP}$ of an LP. This method computes $G^{\rm LP}$ when the LP has only non-redundant inequalities and its feasible set satisfies no equality constraints. However, when the feasible set of the LP satisfies equality constraints this method finds only a subgroup of $G^{\rm LP}$ and can miss symmetries. We develop a method for finding the symmetry group of a feasible LP whose feasible set satisfies equality constraints. We apply this method to find and exploit the previously unexploited symmetries of an orthogonal array defining integer linear program (ILP) within the branch-and-bound (B\&B) with isomorphism pruning algorithm [F. Margot, Symmetric ILP: Coloring and small integers, Discrete Optimization 4 (1) (2007), 40-62]. Our method reduced the running time for finding all OD-equivalence classes of OA$(160,8,2,4)$ and OA$(176,8,2,4)$ by factors of $1/(2.16)$ and $1/(1.36)$ compared to the fastest known method [D. A. Bulutoglu and K. J. Ryan, Integer programming for classifying orthogonal arrays, Australasian Journal of Combinatorics 70 (3) (2018), 362-385]. These were the two bottleneck cases that could not have been solved until the B\&B with isomorphism pruning algorithm was applied.
description: 27 pages
Cyclic Universe and Infinite Past
Creators: name: Frampton, Paul H.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We address two questions about the past for infinitely cyclic cosmology. The first is whether it can contain an infinite length null geodesic into the past in view of the Borde-Guth-Vilenkin (BGV) "no-go" theorem, The second is whether, given that a small fraction of spawned universes fail to cycle, there is an adequate probability for a successful universe after an infinite time. We give positive answers to both questions then show that in infinite cyclicity the total number of universes has been infinite for an arbitrarily long time.
description: 7 pages. Clarification in discussion of infinite past
A Survey of z~6 Quasars in the SDSS Deep Stripe: I. a Flux-Limited Sample at z_{AB}<21
Creators: name: Jiang, Linhua
name: Fan, Xiaohui
name: Annis, James
name: Becker, Robert H.
name: White, Richard L.
name: Chiu, Kuenley
name: Lin, Huan
name: Lupton, Robert H.
name: Richards, Gordon T.
name: Strauss, Michael A.
name: Jester, Sebastian
name: Schneider, Donald P.
Publisher: name: arXiv
Year: 2007
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the discovery of five quasars at z~6 selected from 260 deg^2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the Celestial Equator. The five quasars with 20=6.0 and =-25.8 is (5.0+/-2.1) x 10^{-9} Mpc^{-3} mag^{-1}. We model the bright-end quasar luminosity function (QLF) at z~6 as a power law Phi(L_{1450}) \propto L_{1450}^{beta}. The slope beta calculated from a combination of our sample and the luminous SDSS quasar sample is -3.1+/-0.4, significantly steeper than the slope of the QLF at z~4. Based on the derived QLF, we find that the quasar/AGN population cannot provide enough photons to ionize the intergalactic medium (IGM) at z~6 unless the IGM is very homogeneous and the luminosity (L*_{1450}) at which the QLF power law breaks is very low.
description: 12 pages (emulateapj); submitted to AJ
Fold maps and immersions from the viewpoint of cobordism
Creators: name: Kalmar, Boldizsar
Publisher: name: arXiv
Year: 2007
Subjects: subject: Geometric Topology (math.GT)
subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics
subject: 57R45; 57R75; 57R42; 55Q45

description: We obtain complete geometric invariants of cobordism classes of oriented simple fold maps of (n+1)-dimensional manifolds into an n-dimensional manifold N in terms of immersions with prescribed normal bundles. We compute that this cobordism group of simple fold maps is isomorphic to the direct sum of the (n-1)th stable homotopy group of spheres and the (n-1)th stable homotopy group of the infinite dimensional projective space. By using geometric invariants defined in the author's earlier works, we also describe the natural map of the simple fold cobordism group to the fold cobordism group by natural homomorphisms between cobordism groups of immersions. We also compute the ranks of the oriented (right-left) bordism groups of simple fold maps.
description: revised, 16 pages, 1 figure
Making the Modern Academic Librarian
Creators: name: Sewell, Claire
Publisher: name: Apollo - University of Cambridge Repository
Year: 2017
Subjects: professional development
research support
scholarly communication
librarianship
library and information science

description: Presentation given at CPD25 Staff Development Forum 2017. The nature of the academic library is undergoing a fundamental shift as librarians move away from traditional roles and towards a more active role in supporting the research community at their institutions. However in order to take full advantage of these opportunities library staff need to develop their knowledge of and confidence in the emerging area of scholarly communication. With both time and budgets tight how do managers prepare their staff for future work in academic libraries? This talk will explore some of the methods used by the Office of Scholarly Communication in Cambridge to develop staff knowledge on topics such as Open Access and Research Data Management, discuss the challenges in implementing such programmes and how these can be overcome.
New SU UMa-type star ZTF18abdlzhd in the Zwicky Transient Facility data
Creators: name: Antipin, Sergei V.
name: Zubareva, Alexandra M.
name: Belinski, Aleksandr A.
name: Burlak, Marina A.
name: Ikonnikova, Natalia P.
name: Malanchev, Konstantin L.
name: Kornilov, Matwey V.
name: Mishin, Egor O.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We carried out a search for unknown dwarf novae in a public data release of the Zwicky Transient Facility survey and suspected that the object ZTF18abdlzhd is a SU UMa-type star. Performed multicolor CCD observations permit us to follow its fading from an outburst in August and an entire superoutburst in October 2020. The duration of the superoutburst is 13 days. We detected superhumps with period P = 0.06918(3) d that are characteristic of UGSU type stars.
description: to be published in Contributions of the Astronomical Observatory Skalnat\'e Pleso
Equilibrium on Toeplitz extensions of higher dimensional noncommutative tori
Creators: name: Afsar, Zahra
name: Laca, Marcelo
name: Ramagge, Jacqui
name: Sehnem, Camila F.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Operator Algebras (math.OA)
subject: FOS: Mathematics

description: The C*-algebra generated by the left-regular representation of $\mathbb{N}^n$ twisted by a $2$-cocycle is a Toeplitz extension of an $n$-dimensional noncommutative torus, on which each vector $r \in [0,\infty)^n$ determines a one-parameter subgroup of the gauge action. We show that the equilibrium states of the resulting C*-dynamical system are parametrised by tracial states of the noncommutative torus corresponding to the restriction of the cocycle to the vanishing coordinates of $r$. These in turn correspond to probability measures on a classical torus whose dimension depends on a certain degeneracy index of the restricted cocycle. Our results generalise the phase transition on the Toeplitz noncommutative tori used as building blocks in recent work of Brownlowe, Hawkins and Sims, and of Afsar, an Huef, Raeburn and Sims.
description: 29 pages; minor changes in version 2