cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Body mass predicts isotope enrichment in herbivorous mammals
Creators: name: Tejada-Lara, Julia Victoria
name: MacFadden, Bruce J.
name: Bermudez, Lizette
name: Rojas, Gianmarco
name: Salas-Gismondi, Rodolfo
name: Flynn, John J.
Publisher: name: Columbia University
Year: 2018
Subjects: subject: Body weight
subject: Ecology
subject: FOS: Biological sciences
subject: Stable isotopes in ecological research
subject: Mammals
subject: Isotope separation
subject: Sloths
subject: Paleontology

description: Carbon isotopic signatures recorded in vertebrate tissues derive from ingested food and thus reflect ecologies and ecosystems. For almost two decades, most carbon isotope-based ecological interpretations of extant and extinct herbivorous mammals have used a single diet–bioapatite enrichment value (14‰). Assuming this single value applies to all herbivorous mammals, from tiny monkeys to giant elephants, it overlooks potential effects of distinct physiological and metabolic processes on carbon fractionation. By analysing a never before assessed herbivorous group spanning a broad range of body masses—sloths—we discovered considerable variation in diet–bioapatite d13C enrichment among mammals. Statistical tests (ordinary least squares, quantile, robust regressions, Akaike information criterion model tests) document independence from phylogeny, and a previously unrecognized strong and significant correlation of d13C enrichment with body mass for all mammalian herbivores. A single-factor body mass model outperforms all other single- factor or more complex combinatorial models evaluated, including for physiological variables (metabolic rate and body temperature proxies), and indicates that body mass alone predicts d13C enrichment. These analyses, spanning more than 5 orders of magnitude of body sizes, yield a size-dependent prediction of isotopic enrichment across Mammalia and for distinct digestive physiologies, permitting reconstruction of foregut versus hindgut fermentation for fossils and refined mean annual palaeoprecipitation estimates based on d13C of mammalian bioapatite.
New magnetobiostratigraphic results from the Ladinian of the Dolomites and implications for the Triassic geomagnetic polarity timescale
Creators: name: Maron, Matteo
name: Muttoni, Giovanni
name: Rigo, Manuel
name: Gianolla, Piero
name: Kent, Dennis V.
Publisher: name: Columbia University
Year: 2019
Subjects: Geological time
Paleomagnetism
Uranium-lead dating
Geomagnetism
Triassic Geologic Period

description: We investigated for magnetostratigraphy the Rio Nigra and Rio Frommer stratigraphic sections from Alpe di Siusi/Seiser Alm (Dolomites, northern Italy) in order to improve the calibration of the Triassic time scale. Both sections are characterized by ammonoid and conodont associations typical of Longobardian (late Ladinian, Middle Triassic) age. Moreover, the Rio Nigra section is constrained by a U-Pb zircon date of 237.77 ± 0.05 Ma. Building on the recently veri ed Newark-Hartford astrochronological polarity timescale for the Late Carnian–Rhaetian (plus the Hettangian) and through magnetostratigraphic correlations of an updated inventory of Tethyan marine stratigraphic sections from the literature, some of which are provided with U-Pb zircon age constraints, we propose a revised Geomagnetic Polarity Time Scale for the entire Triassic.
Vertical Information Restraints: Pro- and Anti-Competitive Impacts of Minimum Advertised Price Restrictions
Creators: name: Asker, John W.
name: Bar-Issac, Heski
Publisher: name: Columbia University
Year: 2017
Subjects: Industrial organization
Pricing
Competition
Economics

description: We consider vertical contracts where the retail market may involve search frictions. Minimum advertised price restrictions (MAP) act as a restraint on customers’ information and so can increase search frictions in the retail sector. Such restraints, thereby, soften retail competition—an impact also generated by resale price maintenance (RPM). However, by accommodating (consumer or retailer) heterogeneity, MAP can allow for higher manufacturer profits than RPM. We show that they can do so through facilitating price discrimination among consumers; encouraging service provision; and facilitating manufacturer collusion. Thus, welfare effects may be positive or negative compared to RPM or to the absence of such restrictions.
Strategic Inattention, Inflation Dynamics and the Non-Neutrality of Money
Creators: name: Afrouzi Khosroshahi, Hassan
Publisher: name: Columbia University
Year: 2018
Subjects: Macroeconomics
Inflation (Finance)
Oligopolies
Decision making

description: In countries with low and stable inflation, price setters’ inflation expectations are highly dispersed; especially so when they face fewer competitors. In contrast to the predictions of standard models, realized inflation deviates significantly from price setters’ aggregate infla- tion expectations. Instead, firms’ own-industry inflation expectations are more accurate, and aggregate inflation tracks these expectations closely. This paper poses a new dynamic general equilibrium model of rational inattention with oligopolistic pricing in which these patterns emerge from the optimal choices of firms in information acquisition. A new micro-founded Phillips curve relates aggregate inflation to firms’ expectations about their own competitors’ price changes, and firms optimally forego learning about aggregate variables to focus on their competitors’ beliefs. This incentive is stronger when firms face fewer competitors and non- existent under monopolistic competition. Using firm-level evidence, I calibrate the degree of rational inattention as well as industry concentration and find that, relative to the benchmark of monopolistic competition, the impact response of output (inflation) to a one percent monetary policy shock is 20 basis points larger (smaller) when these strategic incentives are accounted for. Limited competition at the micro-level also increases the half-lives of output and inflation responses to monetary policy shocks by 12% and 15%, respectively.
A prospective, multidisciplinary approach to understanding sport-related head trauma : novel insights into the effects on myelin and cerebrovascular function
Creators: name: Wright, Alexander David
Publisher: name: University of British Columbia
Year: 2017

description: Sport-related concussion occurs at an alarmingly high rate, affecting millions each year. Concern is growing over the effects of repetitive subconcussive head trauma towards the development of long-term neurological deficits. There are calls within sports medicine to shift from symptom-based assessments towards reliable, objective tools to improve identification and management of dangerous levels of sport-related head trauma. The overall objective across the five studies of this thesis was to elucidate the roles of brain myelination and cerebrovascular dysfunction within this context. In study 1, myelin water imaging permitted the first direct evaluation of the effect of sport-related head trauma on myelin integrity. While transient post-concussion disruptions in myelin were observed for at least 2-weeks in multiple brain areas, no myelin changes were observed as a consequence of repetitive subconcussive trauma. Study 2 used transcranial Doppler ultrasound to assess the effects of concussion on indices of dynamic cerebral autoregulation (CA), demonstrating a delay in the CA response to blood pressure alterations persisting beyond symptom resolution that is suggestive of autonomic dysregulation of the cerebrovasculature; deficits did not appear to be cumulative across multiple injuries. Study 3 revealed detrimental effects of one season of contact sport participation on both the timing and magnitude of CA responses related to the degree of exposure to repetitive subconcussive head trauma. Study 4 assessed the effect of concussion on neurovascular coupling (NVC) dynamics within the artery supplying the occipital cortex following visual stimulation, and revealed delays in achieving peak response rate in concert with an elevated response magnitude acutely post-injury with resolution by 1-month; deficits did not appear to accumulate across multiple injuries. Study 5 revealed no changes in NVC dynamics as a function of exposure to one season of participation in contact or non-contact sport, suggesting subconcussive trauma may not impair NVC. Collectively, these results suggest sport-related head trauma can impair myelin integrity and cerebrovascular function; the potential role for autonomic dysregulation towards these findings is discussed. While the effect of repetitive subconcussive trauma on susceptibility to injury remains unclear, the disruptions observed following acute concussion highlight the emerging distinction between clinical and physiological recovery.
The use of fatty acids to identify food sources of secondary consumers in wetland mesocosms
Creators: name: Growns, Ivor
name: Ryder, Darren
name: McInerney, Paul
name: Bond, Nick
name: Holt, Galen
name: Lester, Rebecca
name: Thompson, Ross
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Inorganic Chemistry
subject: FOS: Chemical sciences

description: Increasing demand for freshwater during the last century has so severely degraded many wetland ecosystems that they are some of the most seriously impacted environments in the world. Environmental flows are used as a management tool to restore parts of the hydrological regime altered by human water use, to rehabilitate these wetlands. Research and monitoring to date has focused on understanding ‘flow-ecology’ relationships, without investigating the mechanisms underlying them. We sought to understand how different basal food sources are incorporated into fish tissue in temporary wetland systems. This study provides a necessary first step toward the development of mechanistic research that investigates the effects of variation in fatty acids (FA) within the food and prey base on top predators. We added different sources of fatty acids to wetland mesocosms by adding extra food sources including redgum leachate to increase planktonic bacteria populations, cyanobacteria, green algae and biofilm matrix to observe how they were incorporated into secondary consumers. Wetland soil and water was added to replicate mesocosms, left for 28 days to produce zooplankton and then Western carp gudgeons added. There was a clear shift in the invertebrate assemblage structure following the introduction of the gudgeons. There was also a clear difference in assemblage structure and nutritional value between benthic and planktonic invertebrates. However, the addition of extra food sources did not generate differing FA profiles between treatments in the substratum fractions, invertebrates or fish after 14 days. We suggest that food sources generated within the mesocosms themselves may have outweighed any treatment effects. Using flooded wetland mesocosms potentially would have provided more realistic knowledge of the food web mechanisms of wetland inundation rather than feeding zooplankton fed specific primary food sources to fish. However, future experiments attempting to identify the mechanisms of the transfer of basal food sources in wetlands to secondary consumers may wish to directly feed fish primary consumers raised on specific basal food sources.
Interplay between Fe 3d and Ce 4f magnetism and Kondo interaction in CeFeAs_{1-x}P_{x}O probed by ^{75}As and ^{31}P NMR
Creators: name: Sarkar, R.
name: Baenitz, M.
name: Jesche, A.
name: Geibel, C.
name: Steglich, F.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: A detailed $^{31}$P (I=1/2) and $^{75}$As (I=3/2) NMR study on polycrystalline CeFeAs$_{1-x}$P$_{x}$O alloys is presented. The magnetism of CeFeAsO changes drastically upon P substitution on the As site. CeFePO is a heavy fermion system without long range order whereas CeFeAsO exhibits a Fe-3$d$ SDW type of ordering accompanied by a structural transition from tetragonal ($TT$) to orthorhombic ($OT$) structure. Furthermore Ce-4$f^{1}$ orders antiferromagnetically (AFM) at low temperature. At the critical concentration where the Fe-magnetism is diminished the Ce-Ce interaction changes to a ferromagnetic (FM) type of ordering. Three representative samples of the CeFeAs$_{1-x}$P$_{x}$O ($x$=0.05, 0.3 and 0.9) series are systematically investigated. 1) For the $x$=0.05 alloy a drastic change of the line width at 130 K indicates the AFM-SDW type of ordering of Fe and the structural change from $TT$ to $OT$ phase. The line width roughly measures the internal field in the ordered state and the transition is most likely first order. The small and nearly constant shift for $^{31}$P and $^{75}$As suggests the presence of competing hyperfine interactions between the nuclear spins and the 4$f$ and 3$d$ ions of Ce and Fe. 2) For the $x$=0.3 alloy, evolution of the Fe-SDW type order takes place at around 70 K corroborating the results of bulk measurement and $μSR$. Here we found strong evidence for phase separation of paramagnetic and magnetic SDW phases. 3) In contrast to heavy fermion CeFePO for the $x$=0.9 alloy a phase transition is found at 2 K. The field-dependent NMR shift gives strong evidence of FM ordering. Above the ordering the spin lattice relaxation rate $^{31}$(1/T$_{1}$) shows unconventional, non-Korringa like behaviour which indicates a complex interplay of Kondo and FM fluctuations.
description: 10 (+) pages, 11 figures, Accepted in Journal of Physics condensed Matter
Additional file 1 of Predictors of shorter- and longer-term mortality after COVID-19 presentation among dialysis patients: parallel use of machine learning models in Latin and North American countries
Creators: name: Guinsburg, Adrián M.
name: Jiao, Yue
name: Bessone, María Inés Díaz
name: Monaghan, Caitlin K.
name: Magalhães, Beatriz
name: Kraus, Michael A.
name: Kotanko, Peter
name: Hymes, Jeffrey L.
name: Kossmann, Robert J.
name: Berbessi, Juan Carlos
name: Maddux, Franklin W.
name: Usvyat, Len A.
name: Larkin, John W.
Publisher: name: figshare
Year: 2022
Subjects: subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: 69999 Biological Sciences not elsewhere classified
subject: Developmental Biology
subject: Cancer
subject: Plant Biology
subject: Computational Biology

description: Additional file 1: Supplementary Table 1. Initial, Tuning Range, and Final Hyperparameter Settings for Models. Supplementary Table 2. Mean SHAP values for all predictors of death any time after COVID-19 presentation, by region. Supplementary Table 3. Mean SHAP values for all predictors of death 0-14 days after COVID-19 presentation, by region. Supplementary Table 4. Mean SHAP values for all predictors of death 15-30 days after COVID-19 presentation, by region. Supplementary Table 5. Mean SHAP values for all predictors of death >30 days after COVID-19 presentation, by region.
Gravitons and Breaking the Speed of Light Barrier
Creators: name: AbdulMajid, Basel
Publisher: name: figshare
Year: 2023
Subjects: Mathematical aspects of general relativity

description: According to Einstein's theory of relativity, nothing can travel faster than the speed of light. However, recent research suggests that gravitons, the hypothetical elementary particles that mediate the force of gravity, could potentially break this barrier. In this paper, we will explore the mathematical foundations of this idea and examine its implications.
Identifying the inflaton with primordial gravitational waves
Creators: name: Easson, Damien A.
name: Powell, Brian A.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We explore the ability of experimental physics to uncover the underlying structure of the gravitational Lagrangian describing inflation. While the observable degeneracy of the inflationary parameter space is large, future measurements of observables beyond the adiabatic and tensor two-point functions, such as non-Gaussianity or isocurvature modes, might reduce this degeneracy. We show that even in the absence of such observables, the range of possible inflaton potentials can be reduced with a precision measurement of the tensor spectral index, as might be possible with a direct detection of primordial gravitational waves.
description: 5 pages, 2 figures, version to appear in PRL
The Competitive Effects of Information Sharing
Creators: name: Asker, John W.
name: Fershtman, Chaim
name: Jeon, Jihye
name: Pakes, Ariel
Publisher: name: Columbia University
Year: 2016
Subjects: Industrial organization
Disclosure of information
Antitrust law
Economics

description: We investigate the impact of information sharing between rivals in a dynamic auction with asymmetric information. Firms bid in sequential auctions to obtain inputs. Their inventory of inputs, determined by the results of past auctions, are privately known state variables that determine bidding incentives. The model is analyzed numerically under different information sharing rules. The analysis uses the restricted experience based equilibrium concept of Fershtman and Pakes (2012) which we refine to mitigate multiplicity issues. We find that increased information about competitors’ states increases participation and inventories, as the firms are more able to avoid the intense competition in low inventory states. While average bids are lower, social welfare is unchanged and output is increased. Implications for the posture of antitrust regulation toward information sharing agreements are discussed.
On the bifurcation and continuation of periodic orbits in the three-body problem
Creators: name: Antoniadou, K. I.
name: Voyatzis, G.
name: Kotoulas, T.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Physical sciences

description: We consider the planar three body problem of planetary type and we study the generation and continuation of periodic orbits and mainly of asymmetric periodic orbits. Asymmetric orbits exist in the restricted circular three body problem only in particular resonances called "asymmetric resonances". However, numerical studies showed that in the general three body problem asymmetric orbits may exist not only for asymmetric resonances, but for other kinds, too. In this work, we show the existence of asymmetric periodic orbits in the elliptic restricted problem. These orbits are continued and clarify the origin of many asymmetric periodic orbits in the general problem. Also, we illustrate how the families of periodic orbits of the restricted circular problem and those of the elliptic one join smoothly and form families in the general problem, verifying in this way the scenario described firstly by Bozis and Hadjidemetriou (1976).
description: Published at International Journal of Bifurcation and Chaos (IJBC)
Merging Rates of the First Objects and the Formation of First Mini-Filaments in Models with Massive Neutrinos
Creators: name: Song, Hyunmi
name: Lee, Jounghun
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the effect of massive neutrinos on the formation and evolution of the first filaments containing the first star-forming halos of mass M~10^{6}M_sun at z~20. With the help of the extended Press-Schechter formalism, we evaluate analytically the rates of merging of the first star-forming halos into zero-dimensional larger halos and one-dimensional first filaments. It is shown that as the neutrino mass fraction f_ν increases, the halo-to-filament merging rate increases while the halo-to-halo merging rate decreases sharply. For f_ν<=0.04, the halo-to-filament merging rate is negligibly low at all filament mass scales, while for f_ν>=0.07 the halo-to-filament merging rate exceeds 0.1 at the characteristic filament mass scale of ~10^{9}M_sun. The distribution of the redshifts at which the first filaments ultimately collapse along their longest axes is derived and found to have a sharp maximum at z~8. We also investigate the formation and evolution of the second generation filaments which contain the first galaxies of mass 10^{9}M_sun at z=8 as the parent of the first generation filaments. A similar trend is found: For f_ν>= 0.07 the rate of clustering of the first galaxies into the second-generation filaments exceeds 0.3 at the characteristic mass scale of ~10^{11}M_sun. The longest-axis collapse of these second-generation filaments are found to occur at z~3. The implications of our results on the formation of massive high-z galaxies and the early metal enrichment of the intergalactic media by supernova-driven outflows, and possibility of constraining the neutrino mass from the mass distribution of the high-z central blackholes are discussed.
description: Accepted for publication in ApJ, mistakes in the calculation of the merging rates corrected, feasibility study of constraining neutrino mass with high-z quasar luminosity function presented, discussion improved, 7 figures
Trading Votes for Votes. A Dynamic Theory
Creators: name: Casella, Alessandra M.
name: Palfrey, Thomas R.
Publisher: name: Columbia University
Year: 2018
Subjects: subject: Political science
subject: FOS: Political science
subject: Voting
subject: Economics

description: We develop a framework to study the dynamics of vote trading over multiple binary issues. We prove that there always exists a stable allocation of votes that is reachable in a finite number of trades, for any number of voters and issues, any separable preference profile, and any restrictions on the coalitions that may form. If at every step all blocking trades are chosen with positive probability, convergence to a stable allocation occurs in finite time with probability one. If coalitions are unrestricted, the outcome of vote trading must be Pareto optimal, but unless there are three voters or two issues, it need not correspond to the Condorcet winner. If trading is farsighted, a non-empty set of stable vote allocations reachable from a starting vote allocation need not exist, and if it does exist it need not include the Condorcet winner, even in the case of two issues.
Retention Heterogeneity in New York City Schools
Creators: name: Almond, Douglas V.
name: Lee, Ajin
name: Schwartz, Amy Ellen
Publisher: name: Columbia University
Year: 2016
Subjects: Grade repetition
Academic achievement--Testing
Education
Economics

description: Performance on proficiency exams can be a key determinant of whether students are retained or “held back” in their grade. In New York City, passing the statewide proficiency exam essentially guarantees promotion, while roughly 13% of those students who fail the exam are retained. Using regression discontinuity methods, we find that female students are 25% more likely to be retained in their grade due to exam failure than boys. Hispanic students are 60% more likely and Black students 120% more likely to be retained due to exam failure (relative to White students). Poverty and previous poor performance also increase the likelihood of retention, while being young for grade or short does not. We conclude that “patterned discretion” exists in how standardized test results are utilized.
The Imperfect Fluid behind Kinetic Gravity Braiding
Creators: name: Pujolas, Oriol
name: Sawicki, Ignacy
name: Vikman, Alexander
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We present a standard hydrodynamical description for non-canonical scalar field theories with kinetic gravity braiding. In particular, this picture applies to the simplest galileons and k-essence. The fluid variables not only have a clear physical meaning but also drastically simplify the analysis of the system. The fluid carries charges corresponding to shifts in field space. This shift-charge current contains a spatial part responsible for diffusion of the charges. Moreover, in the incompressible limit, the equation of motion becomes the standard diffusion equation. The fluid is indeed imperfect because the energy flows neither along the field gradient nor along the shift current. The fluid has zero vorticity and is not dissipative: there is no entropy production, the energy-momentum is exactly conserved, the temperature vanishes and there is no shear viscosity. Still, in an expansion around a perfect fluid one can identify terms which correct the pressure in the manner of bulk viscosity. We close by formulating the non-trivial conditions for the thermodynamic equilibrium of this imperfect fluid.
description: 23 pages plus appendices. New version includes extended discussion on diffusion and dynamics in alternative frames, as well as additional references. v3 reflects version accepted for publication in JHEP: minor comments added regarding suitability to numerical approaches
Photoacclimation in freshwater diatoms: interspecific and inter-habitat comparisons
Creators: name: Pengling Shi
name: Xie, Ping
name: Lanhai Liu
name: Jingzhen Cui
name: Xiaoqing Wang
name: Pinhong Yang
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Cell Biology
subject: Physiology
subject: FOS: Biological sciences
subject: Evolutionary Biology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Marine Biology
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
subject: Plant Biology

description: Diatoms are a type of photosynthetic phytoplankton that can acclimate to the light level of their environment. Diatoms from different habitats exhibit different photoacclimation characteristics; those from relatively low-light intensity habitats present relatively high photosynthetic activity, high light-harvesting pigment (Chla) content, and low xanthophyll content. Conversely, diatoms from high-light intensity environments have lower photosynthetic activity, less Chla content, and efficient xanthophyll cycling. Hence, diatoms can maintain high growth and photosynthetic activity within a wide range of light intensities. Whether the mechanisms of such adaptability are a consequence of biological photoacclimation to different light intensities or interspecific differences is unknown. Here, we show that differences in photoacclimation ability are more significant than species differences. We found similar species compositions in low- and high-light habitats of the Hanjiang River, China; however, there were remarkable differences in rapid light-response curve parameters. The photoacclimation of algae and trends in their photosynthetic activity can be estimated by rapid detection techniques. We isolated three diatom species common to both habitats and grew them under various light intensities, finding that they have an excellent ability to acclimate to local light conditions. Diatoms can use physiological strategies to handle light fluctuations, but only for short periods. Our results provide a theoretical basis for controlling algal blooms through light management. With knowledge of the photoacclimation characteristics of diatoms and according to the availability of local water conservancy facilities, it is possible to use light management to control diatom blooms more efficiently than with conventional techniques, thereby reducing water usage.
Evidence for Excimer Photoexcitations in an Ordered π-Conjugated Polymer Film
Creators: name: Aryanpour, K.
name: Sheng, C. -X.
name: Olejnik, E.
name: Pandit, B.
name: Psiachos, D.
name: Mazumdar, S.
name: Vardeny, Z. V.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report pressure-dependent transient picosecond and continuous-wave photomodulation studies of disordered and ordered films of 2-methoxy-5-(2-ethylhexyloxy) poly(para-phenylenevinylene). Photoinduced absorption (PA) bands in the disordered film exhibit very weak pressure dependence and are assigned to intrachain excitons and polarons. In contrast, the ordered film exhibits two additional transient PA bands in the midinfrared that blueshift dramatically with pressure. Based on high-order configuration interaction calculations we ascribe the PA bands in the ordered film to excimers. Our work brings insight to the exciton binding energy in ordered films versus disordered films and solutions. The reduced exciton binding energy in ordered films is due to new energy states appearing below the continuum band threshold of the single strand.
description: 5.5 pages, 5 figures
Explosive phenomena in modified gravity
Creators: name: Arbuzova, E. V.
name: Dolgov, A. D.
Publisher: name: arXiv
Year: 2010
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Observational manifestations of some models of modified gravity, which have been suggested to explain the accelerated cosmological expansion, are analyzed for gravitating systems with time dependent mass density. It is shown that if the mass density rises with time, the system evolves to the singular state with infinite curvature scalar. The corresponding characteristic time is typically much shorter than the cosmological time.
description: 10 pages, 3 figures, version published in PLB, a few references are added and the expression for the frequency of oscillations is corrected
Land Reform and Sex Selection in China
Creators: name: Almond, Douglas V.
name: Li, Hongbin
name: Zhang, Shuang
Publisher: name: Columbia University
Year: 2017
Subjects: Economic development
Land reform
Sex preselection
Economics

description: Following the death of Mao in 1976, agrarian decision-making shifted from the collective to individual households, unleashing rapid growth in farm output and unprecedented reductions in poverty. In new data on reform timing in 914 counties, we find an immediate trend break in the fraction of male children following rural land reform. Among second births that followed a firstborn girl, sex ratios increased from 1.1 to 1.3 boys per girl in the four years following reform. Larger increases are found among families with more education and in counties with larger output gains due to reform. Proximately, increased sex selection was achieved in part through prenatal ultrasounds obtained in provincial capitals. The land reform estimate is robust to controlling for the county-level rollout of the One Child Policy. Overall, we estimate land reform accounted for roughly half of the increase in sex ratios in rural China from 1978-86, or about 1 million missing girls.
Examining lower leg biomechanics during toe-in and toe-out walking in people with medial compartment knee osteoarthritis
Creators: name: Charlton, Jesse M.
Publisher: name: University of British Columbia
Year: 2017

description: Introduction: Knee osteoarthritis is a common and painful disease, and is one of the leading causes of disability in Canada. It is thought that one of the primary causes of disease progression is excessive knee joint loading. Thus, conservative treatments have aimed to reduce knee joint load, predominantly targeting the knee adduction moment – a valid proxy of tibial joint load distribution. Toe-in and toe-out walking are two such strategies which have proven effective in the short term at reducing the knee adduction moment, but still require longer-term assessment and a more thorough understanding of the ancillary effects at joints other than the knee prior to clinical implementation. The ankle joint in particular may be subjected to altered biomechanics during toe-in and toe-out walking. Purpose: The purpose of this thesis was to examine ankle biomechanics during toe-in and toe-out foot rotations in those with medial compartment knee osteoarthritis. Methods: Fifteen individuals with medial compartment knee osteoarthritis were recruited. In a single session, participants were instructed to walk in four conditions guided by real-time biofeedback of performance: 1) toe-in (+10°), 2) neutral (0°), 3) toe-out (-10°) and 4) toe-out (-20°). Ankle kinematics, kinetics and muscle activity were examined during over-ground walking. Results: Toe-out walking exhibited an increase (p=0.011) in peak ankle eversion compared to toe-in walking, while toe-in walking exhibited an increase in ankle inversion at heel strike (p<0.001) and frontal plane ankle angle excursion (p<0.01) compared to toe-out walking. No differences in ankle kinetics were observed. Toe-in walking exhibited a significant increase (p=0.03) in lateral gastrocnemius root mean square muscle activity compared to 20° toe-out. Lastly, toe-in walking was rated as most difficult and least preferred, while neutral walking was rated as least difficult and most preferred. Conclusions: Toe-in and toe-out walking are effective strategies for reducing knee joint load. However, altered ankle biomechanics may increase the risk of adverse events for some individuals. Longer-term studies are required to properly assess the relationship between lower extremity discomfort, ankle biomechanics and altered foot rotation in those with knee OA.
Accretion of Holographic Dark Energy : Dependency only upon Horizon Radius of Expanding Universe
Creators: name: Biswas, Ritabrata
name: Mazumder, Nairwita
name: Chakraborty, Subenoy
Publisher: name: arXiv
Year: 2010
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In this paper we deal with accretion of dark energy in the holographic dark energy model for a general non-rotating static spherically symmetric black hole. The mass of the black hole increases or decreases depending on the nature of the holographic dark energy (quintessence or phantom) as well as on some integration parameters. It is to be illustrated that the enhancement or reduction of mass of a black hole is independent of the mass or size of the black hole itself. Rather it depends only upon the radius of the event horizon of the universe. Finally, the generalized second law of thermodynamics has been studied on the event horizon to be assured that the law holds even if when the black hole mass is decreasing though it is engrossing some mass.
description: 11 pages
Fast, “Robust”, and Approximately Correct: Estimating Mixed Demand Systems
Creators: name: Salanie, Bernard
name: Wolak, Frank
Publisher: name: Columbia University
Year: 2018
Subjects: subject: Industrial organization
subject: Econometrics
subject: FOS: Economics and business
subject: Market share--Econometric models
subject: Economics

description: Many econometric models used in applied work integrate over unobserved heterogeneity. We show that a class of these models that includes many random coefficients demand systems can be approximated by a “small-σ” expansion that yields a straightforward 2SLS estimator. We study in detail the models of market shares popular in empirical IO (“macro BLP”). Our estimator is only approximately correct, but it performs very well in practice. It is extremely fast and easy to implement, and it accommodates to misspecifications in the higher moments of the distribution of the random coefficients. At the very least, it provides excellent starting values for more commonly used estimators of these models.
Tomorrow’s Antitrust Rulings on Conditional Pricing: How the Latest Economic Research May Show the Way
Creators: name: Asker, John W.
name: Akkus-Clemens, Selvin
Publisher: name: Columbia University
Year: 2014
Subjects: Prices
Antitrust law
Economics

description: It is important to distinguish our focus from contracts that explicitly condition on the price of rivals. A good example of this is the most-favored-customer (MFC) agreement. With an MFC agreement, a seller guarantees to match the lowest price a buyer can get from any of the seller’s rivals. By contrast, our focus is on contracts that provide a buyer with price discounts conditional on the level of that buyer’s own purchases.
In Utero Ramadan Exposure and Children’s Academic Performance
Creators: name: Almond, Douglas V.
name: Mazumder, Bhashkar
name: Van Ewijk, Reyn
Publisher: name: Columbia University
Year: 2014
Subjects: Medical economics
Ramadan
Prenatal influences
Academic achievement

description: A large literature has linked the in utero environment to health in adulthood. We consider how prenatal nutrition may shape human capital acquisition in childhood, utilising the month‐long Ramadan fast as a natural experiment. In student register data for Pakistani and Bangladeshi families in England, we examine whether Ramadan's overlap with pregnancy affects subsequent academic outcomes at age 7. We find that test scores are 0.05–0.08 standard deviations lower for students exposed to Ramadan in early pregnancy. Our results suggest that brief prenatal investments may be more cost effective than traditional educational interventions in improving academic performance.
Socialist urban development in the city of Rijeka, Yugoslavia, during the 1960s
Creators: name: Lecki, Dorjan
Publisher: name: University of British Columbia
Year: 2017

description: The city of Rijeka is situated on the point where the Mediterranean Sea penetrates deeply into the European continent. Between 1945 and 1991 the city was governed by the Yugoslav socialist state. As an important industrial center with a wide array of manufacturing economic branches and the largest port in the entire Yugoslav federation, Rijeka witnessed a significant immigration from other parts of the country. During the 1960s and the 1970s the Yugoslav federal government enacted a series of laws that decentralized the state. One of the most notable ones was the Law on Workers’ Self-Management which established workers’ collectives in all major enterprises. The decision-making process was lowered to the local level, and this shift had a significant impact on the urban development process in Rijeka. The urban expansion was a joint effort of four parties – the workers’ collectives, the Council for Urban Planning, the Urbanist Institute, and the large construction companies. These four parties were responsible for Rijeka’s urban development and the creation of Rijeka as a functional Yugoslav socialist city. The interrelation between the major actors in Rijeka’s urban expansion was an important element in the narrative as it produced the urban fabric that is distinctly Yugoslav socialist. The historical heritage, challenging topography, massive immigration, and the multitude of parties involved in the urban development process were some of the notable factors in Rijeka’s urban expansion during the communist rule. However, topography and the official discourse were the most significant challenges to achieve optimal urban development. Therefore, I argue that the urban development process in Rijeka during the Yugoslav socialist period was a result of the interrelation between the Yugoslav communist ideology and the challenging terrain configuration.
Interaction of oblique dark solitons in two-dimensional supersonic nonlinear Schrödinger flow
Creators: name: Annibale, E. S.
name: Gammal, A.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We investigate the collision of two oblique dark solitons in the two dimensional supersonic nonlinear Schrödinger flow past two impenetrable obstacles. We numerically show that this collision is very similar to the dark soliton collisions in the one dimensional case. We observe that it is practically elastic and we measure the shifts of the solitons positions after their interaction.
Demonstration of Choroid Plexus-Subventricular Zone Regulatory (CSR) Axis Mediated by Small Extracellular Vesicles: Toxicological, Molecular, and Neurobehavioral Characterizations
Creators: name: Liu, Luqing
Publisher: name: Purdue University Graduate School
Year: 2023
Subjects: Toxicology (incl. clinical toxicology)

description: The choroid plexus (CP) in brain ventricles secrete cerebrospinal fluid (CSF) that bathes the adjacent subventricular zone (SVZ); the latter is the largest neurogenic region in adult brain harboring neural stem/progenitor cells (NSPCs) and supplies newborn neurons to the olfactory bulb (OB) for normal olfaction. We discovered the presence of a CP-SVZ regulatory (CSR) axis in which the CP, by secreting small extracellular vesicles (sEVs), regulated adult neurogenesis in the SVZ and maintained olfaction. The proposed CSR axis was supported by 1) differential neurogenesis outcomes in the OB when animals treated with intracerebroventricular (ICV) infusion of sEVs collected from the CP of normal or manganese (Mn)-poisoned mice, 2) progressively diminished SVZ adult neurogenesis in mice following CP-targeted knockdown of SMPD3 to suppress CP sEV secretion, and 3) compromised olfactory performance in these CP-SMPD3-knockdown mice. Collectively, our findings demonstrate the biological and physiological presence of this sEV-dependent CSR axis in adult brains.
Estimating the Elasticity of Intertemporal Substitution Using Mortgage Notches
Creators: name: Best, Michael Carlos
name: Cloyne, James
name: Ilzetzki, Ethan
name: Kleven, Henrik
Publisher: name: Columbia University
Year: 2018
Subjects: Elasticity (Economics)
Mortgages
Interest rates
Economics

description: Using a novel source of quasi-experimental variation in interest rates, we develop a new approach to estimating the Elasticity of Intertemporal Substitution (EIS). In the UK, the mortgage interest rate features discrete jumps — notches — at thresholds for the loan-to-value (LTV) ratio. These notches generate large bunching below the critical LTV thresholds and missing mass above them. We develop a dynamic model that links these empirical moments to the underlying structural EIS. The average EIS is small, around 0.1, and quite homogeneous in the population. This finding is robust to structural assumptions and can allow for uncertainty, a wide range of risk preferences, portfolio reallocation, liquidity constraints, present bias, and optimization frictions. Our findings have implications for the numerous calibration studies that rely on larger values of the EIS.
Spatio-kinematic modelling: Testing the link between planetary nebulae and close binaries
Creators: name: Jones, David
name: Tyndall, Amy A.
name: Huckvale, Leo
name: Prouse, Barnabas
name: Lloyd, Myfanwy
Publisher: name: arXiv
Year: 2011
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: It is widely believed that central star binarity plays an important role in the formation and evolution of aspherical planetary nebulae, however observational support for this hypothesis is lacking. Here, we present the most recent results of a continuing programme to model the morphologies of all planetary nebulae known to host a close binary central star. Initially, this programme allows us to compare the inclination of the nebular symmetry axis to that of the binary plane, testing the theoretical expectation that they will lie perpendicular - to date, all have satisfied this expectation, indicating that each nebula has been shaped by its central binary star. As a greater sample of nebulae are modelled, it will be possible to search for trends connecting the parameters of both nebula and central binary, strengthening our understanding of the processes at work in these objects. I will discuss some of the more obvious comparisons, and their current statuses, as well as the obvious links to common envelope evolution.
description: 6 pages to be published in the proceedings of "Evolution of Compact Binaries", ESO - Vi\~na del Mar, March 2011; Evolution of compact binaries. Proceedings of a workshop held at Hotel San Mart\'in, Vi\~na del Mar, Chile 6--11 May 2011
Individuals and Organizations as Sources of State Effectiveness, and Consequences for Policy Design
Creators: name: Best, Michael Carlos
name: Hjort, Jonas K.
name: Szakonyi, David Scott
Publisher: name: Columbia University
Year: 2017
Subjects: Government purchasing
Economic policy
Economics

description: How much of the variation in state effectiveness is due to the individuals and organizations responsible for implementing  policy? We investigate this question and its implications for policy design in the context of public procurement, using a text-based product classification method to measure bureaucratic output. We show that effective procurers lower bid preparation/submission costs, and that 60% of within-product purchase-price variation across 16 million purchases in Russia in 2011-2015 is due to the bureaucrats and organizations administering procurement processes. This has dramatic policy consequences. To illustrate these, we study a ubiquitous procurement policy: bid preferences for favored firms (here domestic manufacturers). The policy decreases overall entry and increases prices when procurers are effective, but has the opposite impact with ineffective procurers, as predicted by a simple endogenous-entry model of procurement. Our results imply that the state’s often overlooked bureaucratic tier is critical for effectiveness and the make-up of optimal policies.
Cascades with Adjoint Matter: Adjoint Transitions
Creators: name: Simic, Dusan
Publisher: name: arXiv
Year: 2010
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: A large class of duality cascades based on quivers arising from non-isolated singularities enjoy adjoint transitions - a phenomenon which occurs when the gauge coupling of a node possessing adjoint matter is driven to strong coupling in a manner resulting in a reduction of rank in the non-Abelian part of the gauge group and a subsequent flow to weaker coupling. We describe adjoint transitions in a simple family of cascades based on a Z2-orbifold of the conifold using field theory. We show that they are dual to Higgsing and produce varying numbers of U(1) factors, moduli, and monopoles in a manner which we calculate. This realizes a large family of cascades which proceed through Seiberg duality and Higgsing. We briefly describe the supergravity limit of our analysis, as well as a prescription for treating more general theories. A special role is played by N=2 SQCD. Our results suggest that additional light fields are typically generated when UV completing certain constructions of spontaneous supersymmetry breaking into cascades, potentially leading to instabilities.
description: 29 pages, a few typos fixed, improved discussion, added figure; now there is 1 figure
Joint IMOTHEP / CAJU workshop on Hybrid Electric Propulsion - FutPrint50
Creators: name: Windels, E.
Publisher: name: Zenodo
Year: 2023
Subjects: IMOTHEP
aviation
greenaviation
H2020Transport
H2020
HorizonEurope
CINEA
CAJU
EU
climatechange
HEP

description: Presentation at the Joint IMOTHEP / CAJU workshop on Hybrid Electric Propulsion (HEP) at Eurocontrol in Brussels (B) on 29 & 30 November 2023.