cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Resolution of a shock in hyperbolic systems modified by weak dispersion
Creators: name: El, G. A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: FOS: Physical sciences

description: We present a way to deal with dispersion-dominated ``shock-type'' transition in the absence of completely integrable structure for the systems that one may characterize as strictly hyperbolic regularized by a small amount of dispersion. The analysis is performed by assuming that, the dispersive shock transition between two different constant states can be modelled by an expansion fan solution of the associated modulation (Whitham) system for the short-wavelength nonlinear oscillations in the transition region (the so-called Gurevich -- Pitaevskii problem). We consider as single-wave so bi-directional systems. The main mathematical assumption is that of hyperbolicity of the Whitham system for the solutions of our interest. By using general properties of the Whitham averaging for a certain class of nonlinear dispersive systems and specific features of the Cauchy data prescription on characteristics we derive a set of transition conditions for the dispersive shock, actually bypassing full integration of the modulation equations. Along with model KdV and mKdV examples, we consider a non-integrable system describing fully nonlinear ion-acoustic waves in collisionless plasma. In all cases our transition conditions are in complete agreement with previous analytical and numerical results.
description: 56 pages, 5 figures. Misprints corrected. References added
Multiwavelength XMM-Newton observations of the Laor et al. sample of PG quasars
Creators: name: Brocksopp, C.
name: Starling, R. L. C.
name: Schady, P.
name: Mason, K. O.
name: Romero-Colmenero, E.
name: Puchnarewicz, E. M.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present XMM-Newton/EPIC spectra for the Laor et al. sample of Palomar Green quasars. We find that a power-law provides a reasonable fit to the 2-5 keV region of the spectra. Excess soft X-ray emission below 2 keV is present for all objects, with the exception of those known to contain a warm absorber. A single power-law is, however, a poor fit to the 0.3-10.0 keV spectrum and instead we find that a simple model, consisting of a broken power-law (plus an iron line), provides a reasonable fit in most cases. The equivalent width of the emission line is constrained in just twelve objects but with low (<2 sigma) significance in most cases. For the sources whose spectra are well-fit by the broken power-law model, we find that various optical and X-ray line and continuum parameters are well-correlated; in particular, the power-law photon index is well-correlated with the FWHM of the Hbeta line and the photon indices of the low and high energy components of the broken power-law are well-correlated with each other. These results suggest that the 0.3-10 keV X-ray emission shares a common (presumably non-thermal) origin, as opposed to suggestions that the soft excess is directly produced by thermal disc emission or via an additional spectral component. We present XMM-Newton/OM data which we combine with the X-ray spectra so as to produce broad-band spectral energy distributions, free from uncertainties due to long-term variability in non-simultaneous data. Fitting these optical-UV spectra with a Comptonized disc model indicates that the soft X-ray excess is independent of the accretion disc, confirming our interpretation of the tight correlation between the hard and soft X-ray spectra.
description: Accepted for publication in MNRAS
Charge density wave and superconductivity competition in Lu$_5$Ir$_4$Si$_{10}$ : a proton irradiation study
Creators: name: Leroux, Maxime
name: Mishra, Vivek
name: Opagiste, Christine
name: Rodière, Pierre
name: Kayani, Asghar
name: Kwok, Wai-Kwong
name: Welp, Ulrich
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Real-space modulated Charge Density Waves (CDW) are an ubiquituous feature in many families of superconductors. In particular, how CDW relates to superconductivity is an active and open question that has recently gathered much interest since CDWs have been discovered in many cuprates superconductors. Here we show that disorder induced by proton irradiation is a full-fledged tuning parameter that can bring essential information to answer this question as it affects CDW and superconductivity with different and unequivocal mechanisms. Specifically, in the model CDW superconductor Lu$_5$Ir$_4$Si$_{10}$ that develops a 1D CDW below 77\,K and s-wave superconductivity below 4\,K, we show that disorder enhances the superconducting critical temperature $T_\mathrm{c}$ and $H_\mathrm{c2}$ while it suppresses the CDW. Discussing how disorder affects both superconductivity and the CDW, we make a compelling case that superconductivity and CDW are competing for electronic density of states at the Fermi level in Lu$_5$Ir$_4$Si$_{10}$, and we reconcile the results obtained via the more common tuning parameters of pressure and doping. Owing to its prototypical, 1D, Peierls type CDW and the s-wave, weak-coupling nature of its superconductivity, this irradiation study of Lu$_5$Ir$_4$Si$_{10}$ provides the basis to understand and extend such studies to the more complex cases of density waves and superconductivity coexistence in heavy fermions, Fe-based or cuprates superconductors.
description: 25 pages single column, 4 figures in main text + 3 figures in appendix
Dense Ionized and Neutral Gas Surrounding Sgr A*
Creators: name: Shukla, Hemant
name: Yun, Min S.
name: Scoville, N. Z.
Publisher: name: arXiv
Year: 2004
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present high resolution H41a hydrogen recombination line observations of the 1.2' (3 pc) region surrounding Sgr A* at 92 GHz using the OVRO Millimeter Array with an angular resolution of 7" x 3" and velocity resolution of 13 km/s. New observations of H31a, H35a, H41a, and H44a lines were obtained using the NRAO 12-m telescope, and their relative line strengths are interpreted in terms of various emission mechanisms. These are the most extensive and most sensitive observations of recombination line to date. Observations of HCO+ (1 - 0) transition at 89 GHz are also obtained simultaneously with a 40% improved angular resolution and 4-15 times improved sensitivity over previous observations, and the distribution and kinematics of the dense molecular gas in the circumnuclear disk (CND) are mapped and compared with those of the ionized gas. The line brightness ratios of the hydrogen recombination lines are consistent with purely spontaneous emission from 7000 K gas with n_e = 20,000 cm$^{-3}$ near LTE condition. A virial analysis suggests that the most prominent molecular gas clumps in the CND have mean densities of 10^7 cm^{-3}, sufficient to withstand the tidal shear in the Galactic Center region. Therefore, these clumps may survive over several dynamical times, and the CND may be a dynamically stable structure. We estimate a total gas mass of 3 x 10^5 solar mass for the CND. \
description: 34 pages including 11 figures (4 jpgs), Latex, uses aastex. The full pdf format file including high resolution figures is available at http://www.astro.umass.edu/~myun/papers/SgrA.pdf . To appear in the 20 November 2004 (V616) issue of the Astrophysical Journal
Searching for Boosted Dark Matter mediated by a new Gauge Boson
Creators: name: Cho, Wonsub
name: Choi, Ki-Young
name: Yoo, Seong Moon
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We study the possibility to directly detect the boosted dark matter generated from the scatterings with high energetic cosmic particles such as protons and electrons. As a concrete example, we consider the sub-GeV dark matter mediated by a $U(1)_D$ gauge boson which has mixing with $U(1)_Y$ gauge boson in the standard model. The enhanced kinetic energy of the light dark matter from the collision with the cosmic rays can recoil the target nucleus and electron in the underground direct detection experiments transferring enough energy to them to be detectable. We show the impact of BDM with existing direct detection experiments as well as collider and beam-dump experiments.
description: 11 pages, 8 figures, accepted version by PRD
Theoretical investigations for shot noise in correlated resonant tunneling through a quantum coupled system
Creators: name: Djuric, Ivana
name: Dong, Bing
name: Cui, H. L.
Publisher: name: arXiv
Year: 2004
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: In this paper, we carry out a theoretical analysis of the zero-frequency and finite-frequency shot noise in electron tunneling through a two-level interacting system connected to two leads, when a coherent coupling between the two levels is present, by means of recently developed bias-voltage and temperature dependent quantum rate equations. For this purpose, we generalize the traditional generation-recombination approach for shot noise of two-terminal tunneling devices properly to take into account the coherent superposition of different electronic states (quantum effects). As applications, analytical and numerical investigations have been given in detail for two cases: (1) electron tunneling through a quantum dot connected to ferromagnetic leads with intradot spin-flip scattering, and (2) spinless fermions tunneling through seriesly coupled quantum dots, focusing on the shot noise as functions of bias-voltage and frequency.
description: 12 pages, 10 figures, an extension of cond-mat/0406679
A Subjective Approach to Quantum Probability
Creators: name: Lehrer, E.
name: Shmaya, E.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: A likelihood order is defined over linear subspaces of a finite dimensional Hilbert space. It is shown that such an order that satisfies some plausible axioms can be represented by a quantum probability in two cases: pure state and uniform measure.
description: 17 pages
Environmental offsets and other market approaches with specific reference to the Olifants River (East) and Berg River
Creators: name: Nieuwoudt, W. Lieb
name: Nieuwoudt, W. Lieb
Publisher: name: Unknown
Year: 2008
Subjects: subject: environmental offsets
subject: pollution permits
subject: Olifants River (East)

description: Biodiversity offsets for a river create the incentive for cooperation amongst stakeholders with benefits to the environment. Because of the isolation paradox supporting institutions need to be created to facilitate cooperation. Environmental pollution caused by mining activity is a problem in the Olifants River (East) in South Africa. The catchment surface is fractured by mining activities and water is drained into underground aquifers, after which it seeps into streams. Mines have been permitted to release nutrients in the streams during periods of high flow, which is called the “controlled release scheme”. A main problem is the effluent leakage from old disused mines during times when river flow is low and not sufficient dilution of nutrients is possible. DWAF (Department of Water Affairs and Forestry) has accepted ownership of these mines but they may not have the technology (which is expensive) to desalinate the effluent. In an offsetting arrangement, incentives can be provided to existing mines to desalinate water from these defunct mines by allowing them to discharge a given amount in the Olifants when the water flow is sufficiently high. The above arrangement will cost the taxpayer nothing while discharge during low flow periods is reduced. A discussion was held with stakeholders of the Olifants River Forum during 2006 and support was received for some of these policy options. It is shown how offsets can mitigate negative effects of dam construction. It is further proposed that tradable pollution permits be adopted which are subject to a rule that discharges in the river are only allowed when flow is sufficiently high and that trades may only occur within certain parameters.
Dynamics of in-plane charge separation front in 2D electron-hole gas
Creators: name: Chen, Gang
name: Rapaport, Ronen
name: Simon, Steven H.
name: Pfeiffer, Loren
name: West, Ken
Publisher: name: arXiv
Year: 2004
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We show both experimentally and theoretically that the recently observed optically induced in-plane charge separation in quantum well (QW) structures and the exciton ring emission pattern at this charge separation boundary have an extremely long lifetime. The oppositely charged carriers remain separated and provide a reservoir of excitons at their boundary with a persistent emission which lasts hundreds of microseconds (orders of magnitude longer than their recombination time) after the external excitation is removed. This long lifetime is due to an interplay between the slow in-plane carrier diffusion and slow carrier tunnelling perpendicular to the QW plane.
description: 13 pages, 4 figures
Additional file 1 of Effect of metabolically healthy obesity on the development of arterial stiffness: a prospective cohort study
Creators: name: Yuan, Yue
name: Mu, Jian-Jun
name: Chu, Chao
name: Zheng, Wen-Ling
name: Wang, Yang
name: Hu, Jia-Wen
name: Ma, Qiong
name: Yan, Yu
name: Yue-Yuan Liao
name: Chen, Chen
Publisher: name: figshare
Year: 2020
Subjects: subject: Medicine
subject: Cell Biology
subject: Genetics
subject: FOS: Biological sciences
subject: Physiology
subject: Biotechnology
subject: Developmental Biology
subject: Cancer
subject: Computational Biology

description: Additional file 1 Adjusted odds ratios and 95% confidence intervals of the association of metabolic health and obesity with high baPWV by sex in 2017 (n = 2076).
Dominant Voices and Legitimising Discourses in News Reporting on Private Prisons in Victoria and South Australia, 2010-2019
Creators: name: Savage, Aislinn
Publisher: name: La Trobe
Year: 2025
Subjects: classificationCode: 440212
subject: Private policing and security services
classificationCode: 470107
subject: Media studies
classificationCode: 440801
subject: Australian government and politics

description: A thesis submitted in total fulfilment of the requirements for the degree of Master of Arts to the School of Humanities and Social Sciences, La Trobe University, Victoria, Australia.
Hysteresis multicycles in nanomagnet arrays
Creators: name: Deutsch, J. M.
name: Mai, Trieu
name: Narayan, Onuttom
Publisher: name: arXiv
Year: 2004
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We predict two new physical effects in arrays of single-domain nanomagnets by performing simulations using a realistic model Hamiltonian and physical parameters. First, we find hysteretic multicycles for such nanomagnets. The simulation uses continuous spin dynamics through the Landau-Lifshitz-Gilbert (LLG) equation. In some regions of parameter space, the probability of finding a multicycle is as high as ~0.6. We find that systems with larger and more anisotropic nanomagnets tend to display more multicycles. This result demonstrates the importance of disorder and frustration for multicycle behavior. We also show that there is a fundamental difference between the more realistic vector LLG equation and scalar models of hysteresis, such as Ising models. In the latter case, spin and external field inversion symmetry is obeyed but in the former it is destroyed by the dynamics, with important experimental implications.
description: 7 pages, 2 figures
Partition functions and thermodynamic properties of paraboson and parafermion systems
Creators: name: Stoilova, N. I.
name: Van der Jeugt, J.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: New formulas are given for the grand partition function of paraboson systems of order p with n orbitals and parafermion systems of order p with m orbitals. These formulas allow the computation of statistical and thermodynamic functions for such systems. We analyze and discuss the average number of particles on an orbital, and the average number of particles in the system. For some special cases (identical orbital energies, or equidistant orbital energies) we can simplify the grand partition functions and describe thermodynamic properties in more detail. Some specific properties are also illustrated in plots of thermodynamic functions.
Additional file 2 of Protocol for a randomized controlled trial comparing wound COmplications in elective midline laparotomies after FAscia Closure using two different Techniques Of Running sutures: COFACTOR trial
Creators: name: Charif, Mohamad Hadi El
name: Hassan, Zeina
name: Hoballah, Jamal
name: Khalife, Mohamad
name: Sbaity, Eman
Publisher: name: figshare
Year: 2020
Subjects: subject: Medicine
subject: Physiology
subject: FOS: Biological sciences
subject: Biotechnology
subject: Immunology
subject: FOS: Clinical medicine
subject: Cancer
subject: 111714 Mental Health
subject: FOS: Health sciences
subject: 110309 Infectious Diseases

description: Additional file 2. Appendices.
The Logic Backbone of a Transcription Network
Creators: name: Lagomarsino, M. Cosentino
name: Jona, P.
name: Bassetti, B.
Publisher: name: arXiv
Year: 2004
Subjects: subject: Molecular Networks (q-bio.MN)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: A great part of the effort in the study of coarse grained models of transcription networks is directed to the analysis of their dynamical features. In this letter, we consider the \emph{equilibrium} properties of such systems, showing that the logic backbone underlying all dynamic descriptions has the structure of a computational optimization problem. It involves variables, which correspond to gene expression levels, and constraints, which describe the effect of \emph{cis-}regulatory signal integration functions. In the simple paradigmatic case of Boolean variables and signal integration functions, we derive and discuss phase diagrams. Notably, the model exhibits a connectivity transition between a regime of simple, but uncertain, gene control, to a regime of complex combinatorial control.
description: 11 pages, 4 figures final
Flux growth of Sr(n+1)Ir(n)O(3n+1) [n=1, 2, infinity] crystals
Creators: name: Manna, Kaustuv
name: Aslan-Cansever, Gizem
name: Maljuk, Andrey
name: Wurmehl, Sabine
name: Seiro, Silvia
name: Büchner, Bernd
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Single crystals of iridates are usually grown by a flux method well above the boiling point of the SrCl2 solvent. This leads to non-equilibrium growth conditions and dramatically shortens the lifetime of expensive Pt crucibles. Here, we report the growth of Sr2IrO4, Sr3Ir2O7 and SrIrO3 single crystals in a reproducible way by using anhydrous SrCl2 flux well below its boiling point. We show that the yield of the different phases strongly depends on the nutrient/solvent ratio for fixed soak temperature and cooling rate. Using this low-temperature growth approach generally leads to a lower temperature-independent contribution to the magnetic susceptibility than previously reported. Crystals of SrIrO3 exhibit a paramagnetic behavior that can be remarkably well fitted with a Curie-Weiss law yielding physically reasonable parameters, in contrast to previous reports. Hence, reducing the soak temperature below the solvent boiling point not only provides more stable and controllable growth conditions in contrast to previously reported growth protocols, but also extends considerably the lifetime of expensive platinum crucibles and reduces the corrosion of heating and thermoelements of standard furnaces, thereby reducing growth costs.
description: Accepted in Journal of Crystal Growth
The structure of nearly isothermal, adiabatic shockwaves
Creators: name: Coughlin, Eric R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: An explosively generated shockwave with time-dependent radius $R(t)$ is characterized by a phase in which the shocked gas becomes radiative with an effective adiabatic index $γ\simeq 1$. Using the result that the post-shock gas is compressed into a shell of width $ΔR/R \simeq δ$, where $δ= γ-1$, we show that a choice of self-similar variable that exploits this compressive behavior in the limit that $γ\rightarrow 1$ naturally leads to a series expansion of the post-shock fluid density, pressure, and velocity in the small quantity $δ$. We demonstrate that the leading-order (in $δ$) solutions, which are increasingly accurate as $γ\rightarrow 1$, can be written in simple, closed forms when the fluid is still approximated to be in the energy-conserving regime (i.e., the Sedov-Taylor limit), and that the density declines exponentially rapidly with distance behind the shock. We also analyze the solutions for the bubble surrounding a stellar or galactic wind that interacts with its surroundings, and derive expressions for the location of the contact discontinuity that separates the shocked ambient gas from the shocked wind. We discuss the implications of our findings in the context of the dynamical stability of nearly isothermal shocks.
description: 5 pages, 2 figures, MNRASL Accepted
One-loop running of dimension-six Higgs-neutrino operators and implications of a large neutrino dipole moment
Creators: name: Chala, Mikael
name: Titov, Arsenii
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We compute the one-loop running of the dimension-six CP-even Higgs operators in the Standard Model effective field theory involving the right-handed component of the would-be Dirac neutrinos. We discuss the implications of a large Dirac neutrino magnetic dipole moment. In particular, we demonstrate that a neutrino magnetic moment explaining the recent XENON1T excess induces Higgs and $Z$ invisible decays with branching ratios in the range $[10^{-18}, 10^{-12}]$. These numbers are unfortunately beyond the reach of current and near future facilities.
description: 27 pages, 7 figures, 2 tables, 1 matrix; Feynman diagrams made nicer; typos corrected; matches version published in JHEP
Planetary Nebulae Kinematics in M31
Creators: name: Hurley-Keller, Denise
name: Morrison, Heather L.
name: Harding, Paul
name: Jacoby, George
Publisher: name: arXiv
Year: 2004
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present kinematics of 135 planetary nebulae in M31 from a survey covering 3.9 square degrees and extending out to 15 kpc from the southwest major axis and more than 20 kpc along the minor axis. The majority of our sample, even well outside the disk, shows significant rotational support (mean line-of-sight velocity 116 km/s). We argue that these PN belong to the outer part of M31's large de Vaucouleurs bulge. Only five PN have velocities clearly inconsistent with this fast rotating bulge. All five may belong to tidal streams in M31's outer halo. One is projected on the Northern Spur, and is counter-rotating with respect to the disk there. Two are projected along the major axis at X=-10 kpc and have M32-like velocities; they could be debris from that galaxy. The remaining two halo PN are located near the center of the galaxy and their velocities follow the gradient found by Ibata et al. (2004), implying that these PN could belong to the Southern Stream. If M31 has a non-rotating, pressure-supported halo, we have yet to find it, and it must be a very minor component of the galaxy.
description: accepted to ApJ; main body of paper is 36 pages, including 14 figures
Factors enhancing market participation by small-scale cotton farmers
Creators: name: Randela, Rendani
name: Alemu, Zerihun Gudeta
name: Groenewald, Jan A.
name: Randela, Rendani
name: Alemu, Zerihun Gudeta
name: Groenewald, Jan A.
Publisher: name: Unknown
Year: 2008
Subjects: subject: market participation
subject: household commercialisation
subject: logistic regression
subject: transaction costs

description: This paper uses data collected from 177 small-scale farming households in Mpumalanga in an effort to identify factors that significantly influence the degree of commercialisation or market participation. A logistic regression model was applied within the transaction costs framework. Results support the hypothesis that transactions costs rank among the main determinants of commercialisation. The following variables were statistically significant: age, ability to speak/understand English, region, ownership of transport, access to market information, distance to market, dependency ratio, trust, land size and ownership of livestock. Increases in the latter four have negative effects on commercialisation. The negative relationship between land size and commercialisation probably indicates that increased market participation is also a function of input (land) productivity.
One-loop mass shift formula for kinks and self-dual vortices
Creators: name: Izquierdo, A. Alonso
name: Fuertes, W. Garcia
name: Mayado, M. de la Torre
name: Guilarte, J. Mateos
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: A formula is derived that allows us to compute one-loop mass shifts for kinks and self-dual Abrikosov-Nielsen-Olesen vortices. The procedure is based in canonical quantization and heat kernel/zeta function regularization methods.
description: LaTex file, 8 pages, 1 figure . Based on a talk given by J. M. G. at the 7th Workshop on Quantum Field Theory under the Influence of External Conditions (QFEXT05), Barcelona, Spain. Minor corrections. Version to appear in Journal of Physics A
Runaway collisions in young star clusters. I. Methods and tests
Creators: name: Freitag, Marc
name: Rasio, Frederic A.
name: Baumgardt, Holger
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We present the methods and preparatory work for our study of the collisional runaway scenario to form a very massive star (VMS, M > 400 Msun) at the centre of a young, compact stellar cluster. In the first phase of the process, a very dense central core of massive stars (M =~ 30-120 Msun) forms through mass segregation and gravothermal collapse. This leads to a collisional stage, likely to result in the formation of a VMS (itself a possible progenitor for an intermediate-mass black hole) through a runaway sequence of mergers between the massive stars. In this paper we present the runaway scenario in a general astrophysical context. We then explain the numerical method used to investigate it. Our approach is based on a Monte Carlo code to simulate the stellar dynamics of spherical star clusters using a very large number of particles (a few 1e5 to several 1e6). Finally, we report on test computations carried out to ensure that our implementation of the important physics is sound. In a second paper, we present results from more than 100 cluster simulations realized to determine the conditions leading to the collisional formation of a VMS and the characteristics of the runaway sequences.
description: 22 pages, 15 figures. For publication in MNRAS. Paper revised to follow requests and suggestions of referee. Companion paper to Freitag, G\"urkan & Rasio 2005 (astro-ph/0503130)
Institutions and economic research: a case of location externalities on agricultural resource allocation in the Kat River basin, South Africa
Creators: name: Mbatha, C. Nhlanhla
name: Antrobus, G.G.
name: Mbatha, C. Nhlanhla
name: Antrobus, G.G.
Publisher: name: Unknown
Year: 2008
Subjects: subject: institutions
subject: water allocation
subject: physical externality
subject: Kat River Valley

description: The Physical Externality Model is used to illustrate the potential limitations of blindly adopting formal models for economic investigation and explanation in varied geographical contexts. As argued by institutional economists for the last hundred years the practice limits the value and relevance of most general economic inquiry. This model postulates that the geographical location of farmers along a given watercourse, in which water is diverted individually, leads to structural inefficiencies that negatively affect the whole farming community. These effects are felt more severely at downstream sites and lead to a status quo where upstream farmers possess relative economic and political advantages over their counterparts elsewhere. In the study of the Kat River basin these predictions appear to be true only in as far as they relate to legal and political allocations and use of water resources. In terms of lawful uses of land resources aimed at expanding citrus production, the model’s predictions are not met. The status quo is however fully explained by the implications of having adopted formal water scheduling rights by upstream farmers as well as other geographical factors. Hence, the case for investigating the effects of important institutions within general economic research is strengthened.
Detection of missing low-lying atomic states in actinium
Creators: name: Zhang, Ke
name: Studer, Dominik
name: Weber, Felix
name: Gadelshin, Vadim M.
name: Kneip, Nina
name: Raeder, Sebastian
name: Budker, Dmitry
name: Wendt, Klaus
name: Kieck, Tom
name: Porsev, Sergey G.
name: Cheung, Charles
name: Safronova, Marianna S.
name: Kozlov, Mikhail G.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Two lowest-energy odd-parity atomic levels of actinium, 7s^27p 2P^o_1/2, 7s^27p 2P^o_3/2, were observed via two-step resonant laser-ionization spectroscopy and their respective energies were measured to be 7477.36(4) cm^-1 and 12 276.59(2) cm^-1. The lifetimes of these states were determined as 668(11) ns and 255(7) ns, respectively. In addition, these properties were calculated using a hybrid approach that combines configuration interaction and coupled-cluster methods in good agreement. The data are of relevance for understanding the complex atomic spectra of actinides and for developing efficient laser-cooling and ionization schemes for actinium, with possible applications for high-purity medicalisotope production and future fundamental physics experiments with this atom.
description: 6pages, 5figures
Estimating stellar oscillation-related parameters and their uncertainties with the moment method
Creators: name: De Ridder, Joris
name: Molenberghs, Geert
name: Aerts, Conny
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: The moment method is a well known mode identification technique in asteroseismology (where `mode' is to be understood in an astronomical rather than in a statistical sense), which uses a time series of the first 3 moments of a spectral line to estimate the discrete oscillation mode parameters l and m. The method, contrary to many other mode identification techniques, also provides estimates of other important continuous parameters such as the inclination angle alpha, and the rotational velocity v_e. We developed a statistical formalism for the moment method based on so-called generalized estimating equations (GEE). This formalism allows the estimation of the uncertainty of the continuous parameters taking into account that the different moments of a line profile are correlated and that the uncertainty of the observed moments also depends on the model parameters. Furthermore, we set up a procedure to take into account the mode uncertainty, i.e., the fact that often several modes (l,m) can adequately describe the data. We also introduce a new lack of fit function which works at least as well as a previous discriminant function, and which in addition allows us to identify the sign of the azimuthal order m. We applied our method to the star HD181558, using several numerical methods, from which we learned that numerically solving the estimating equations is an intensive task. We report on the numerical results, from which we gain insight in the statistical uncertainties of the physical parameters involved in the moment method.
description: The electronic online version from the publisher can be found at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-9876.2005.00487.x
Gravitational reheating and superheavy Dark Matter creation after inflation with non-minimal coupling
Creators: name: Babichev, E.
name: Gorbunov, D.
name: Ramazanov, S.
name: Reverberi, L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We discuss the gravitational creation of superheavy particles $χ$ in an inflationary scenario with a quartic potential and a non-minimal coupling between the inflaton $φ$ and the Ricci curvature: $ξφ^2 R/2$. We show that for large constants $ξ>> 1$, there can be abundant production of particles $χ$ with masses largely exceeding the inflationary Hubble rate $H_{infl}$, up to $(a~few) \times ξH_{infl}$, even if they are conformally coupled to gravity. We discuss two scenarios involving these gravitationally produced particles $χ$. In the first scenario, the inflaton has only gravitational interactions with the matter sector and the particles $χ$ reheat the Universe. In this picture, the inflaton decays only due to the cosmic expansion, and effectively contributes to dark radiation, which can be of the observable size. The existing limits on dark radiation lead to an upper bound on the reheating temperature. In the second scenario, the particles $χ$ constitute Dark Matter, if substantially stable. In this case, their typical masses should be in the ballpark of the Grand Unification scale.
description: 26 pages, 3 figures; minor changes; matches journal version
The causal effects of religious service attendance on prosocial behaviours in New Zealand: A national longitudinal study
Creators: name: Bulbulia, Joseph
name: Davis, DE
name: Rice, KG
name: Sibley, CG
name: Troughton, Geoffrey
Publisher: name: Open Access Te Herenga Waka-Victoria University of Wellington
Year: 2025
Subjects: classificationCode: 5205
subject: Social and personality psychology
classificationCode: 52
subject: Psychology
subject: FOS: Psychology

description: We investigate the causal effects of religious service attendance on prosocial behaviours using longitudinal data from a nationally representative sample of 33,198 New Zealanders collected between 2018 and 2021. Our study innovates in three ways: (1) we use longitudinal rather than cross-sectional data; (2) we incorporate measures of help received alongside self-reported giving; and (3) our statistical models are designed to address causal questions, rather than simply to describe change over time. We model causal contrasts for three hypothetical interventions – increasing, decreasing, or maintaining religious service attendance – and assess their effects on eight distinct prosocial domains. Study 1 focuses on self-reported charitable donations and volunteering. Studies 2 and 3 examine receiving help – both personal and financial – from family, friends, and the wider community. Across all analyses, we find that the causal effects of religious service attendance are notably smaller than cross-sectional correlations suggest. However, even modest increases in regular attendance would result in charitable donations equivalent to approximately 4% of the New Zealand Government’s annual spending – a considerable public benefit. By applying robust methods for causal inference to national-scale panel data, our study provides insights that can inform public policy about the social functions of religious participation and advances a methodological framework for investigating the social consequences of cultural practices.
High Precision Calibration Pairs for Southern Lucky Imaging
Creators: name: James, Matthew B.
name: White, Graeme L.
name: Letchford, Roderick R.
name: Bosi, Stephen
Publisher: name: arXiv
Year: 2020
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Accurate measures of double stars require accurate calibration of the instrument. Here we present a list of 50 pairs, that are quasi-evenly spaced over the southern sky, and that have Separations and Position Angles accurate at the milli-arcsec, and milli-degree level. These wide angle pairs are suggested as calibration pairs for lucky imaging observations.
description: 2 Figure, 3 Tables, 10 Pages
Stochastic averaging level control and its application to broke management in paper machines
Creators: name: Ogawa, Shiro
Publisher: name: University of British Columbia
Year: 2009

description: Averaging level control refers to liquid level control of storage tanks, where the objective is to keep the outlet flow u(t) as smooth as possible against the fluctuating inlet flow, while at the same time keeping the tank level y(t) within high and low limits. The thesis treats the stochastic averaging level control problem, where the input disturbance is a stochastic process. The problem is formulated to minimize a weighted sum of Var[u(t)] and Var[u(t)] subject to the target Var[y(t)]. The state-space linear quadratic optimal control method is used, resulting in a linear state feedback controller. When the input disturbance is modelled as the output of a first-order low-pass filter driven by white noise, the optimal controller is a phase-lag network. Broke storage tank level control is important in stabilizing the paper machine wet end. It is treated as a special type of averaging level control, where the input disturbance F[sub b](t) is a two-state continuous-time Markov process. The spectrum of F[sub b](t) is obtained and the linear optimal controller is designed with the same methodology as for the general averaging level control problem. Taking this very specific nature of F[sub b](t), a new nonlinear control scheme called the minimum overflow probability controller (MOPC) is designed, and tested against data collected from a paper machine. The MOPC performs better than the optimal linear controller and manual control. A new theorem on the state probability distribution of a continuous-time Markov jump system is presented, which leads to new methods for evaluating the mean and the variance of the state of a linear jump system, and a new reliable numerical method to calculate the state distributions of jump systems. These results are utilized to evaluate the overflow probabilities of controllers.
Methods in causal inference. Part 3: measurement error and external validity threats
Creators: name: Bulbulia, Joseph
Publisher: name: Open Access Te Herenga Waka-Victoria University of Wellington
Year: 2025
Subjects: classificationCode: 44
subject: Human society
classificationCode: 4301
subject: Archaeology
classificationCode: 4401
subject: Anthropology
subject: FOS: Sociology

description: The human sciences should seek generalisations wherever possible. For ethical and scientific reasons, it is desirable to sample more broadly than ‘Western, educated, industrialised, rich, and democratic’ (WEIRD) societies. However, restricting the target population is sometimes necessary; for example, young children should not be recruited for studies on elderly care. Under which conditions is unrestricted sampling desirable or undesirable? Here, we use causal diagrams to clarify the structural features of measurement error bias and target population restriction bias (or ‘selection restriction’), focusing on threats to valid causal inference that arise in comparative cultural research. We define any study exhibiting such biases, or confounding biases, as weird (wrongly estimated inferences owing to inappropriate restriction and distortion). We explain why statistical tests such as configural, metric and scalar invariance cannot address the structural biases of weird studies. Overall, we examine how the workflows for causal inference provide the necessary preflight checklists for ambitious, effective and safe comparative cultural research.
Producer price and price transmission in a deregulated Ethiopian coffee market
Creators: name: Worako, Tadesse Kumma
name: Van Schalkwyk, Herman D.
name: Alemu, Zerihun Gudeta
name: Ayele, Gezahegn
name: Worako, Tadesse Kumma
name: Van Schalkwyk, Herman D.
name: Alemu, Zerihun Gudeta
name: Ayele, Gezahegn
Publisher: name: Unknown
Year: 2008
Subjects: subject: market deregulation
subject: producer price
subject: price transmission
subject: price asymmetry

description: Coffee producers in Ethiopia have historically received a very small share of the export price of green coffee. Reasons that are often mentioned are heavy government intervention and high marketing and processing costs. Prior to 1992, government regulation of the domestic coffee market in the form of fixed producer prices and the monopoly power of the Ethiopian Coffee Marketing Corporation put a substantial wedge between the producer price and the world price of coffee by imposing an implicit tax on producers. The domestic coffee marketing system in Ethiopia was liberalised after 1992, which was envisaged to have a positive effect on producer prices and price transmission signals from world markets to producers. This paper, with the help of Cointegration and Error-Correction Model (ECM), attempts to analyse its impact. As findings indicate, the reforms induced stronger long-run relationships among grower, wholesaler and exporter prices. The estimation of the ECM shows that the short-run transmission of price signals from world to domestic markets has improved, but has remained weak in both auction-to-world and producer-to-auction markets. This might be explained by the weak institutional arrangement coordinating the domestic coffee system and contract enforcement. In general, the domestic price adjusts more rapidly to world price changes today than it did prior to the reforms. However, there is an indication that negative price changes transmit much faster than positive ones.
Photon avalanche up-conversion in NdAl$_3$(BO$_3$)$_4$ nanoparticles excited at 1064 nm
Creators: name: da Silva, Jefferson F.
name: da Silva, Rodrigo F.
name: Santos, Emanuel P.
name: Maia, Lauro J. Q.
name: Moura, André L.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We report efficient non-resonant ground state excitation at 1064 nm of trivalent neodymium (Nd$^{3+}$) ions in stoichiometric neodymium aluminum borate NdAl$_3$(BO$_3$)$_4$ nanoparticles, which are crystalline and, besides the large content of Nd$^{3+}$ ions, present excellent photoluminescence properties. Up-conversions (UCs) were observed and the energy pathways identified, as starting by multi-phonon assisted ground state absorption ($^4$I$_{9/2}$-$^4$F$_{3/2}$) and excited state absorption ($^4$I$_{11/2}$-$^4$F$_{3/2}$) with the population of the $^4$I$_{11/2}$ level by thermal coupling with the ground state. The excited state $^4$I$_{11/2}$ is also populated by relaxations of the Nd$^{3+}$ ions increasing the population of the $^4$F$_{3/2}$ level. Cross-relaxation among two Nd$^{3+}$ ions ($^4$F$_{3/2}$,$^4$I$_{9/2}$)-($^4$I$_{15/2}$,$^4$I$_{15/2}$) with subsequent phonon emission leads to two ions at the $^4$I$_{11/2}$ level every iteration triggering a photon avalanche mechanism which greatly enhances the efficiency of the UCs. Ladder thermal excitation $^4$F$_{3/2}$-[$^4$F$_{5/2}$,$^2$H$_{9/2}$]-[$^4$F$_{7/2}$,$^4$S$_{3/2}$]-$^4$F$_{9/2}$ was achieved, and the ground state relaxation from these levels provided emission at 880 nm, 810 nm, 750 nm, and 690 nm, respectively. Energy transfer UCs (Auger) between Nd$^{3+}$ ions at the $^4$F$_{3/2}$ level allowed the population of the [$^2$G$_{3/2}$,$^4$G$_{7/2}$] from which relaxations to the $^4$I$_{9/2}$, $^4$I$_{11/2}$, and $^4$I$_{13/2}$ states provided emissions around 536 nm, 600 nm, and 660 nm, respectively. Associated with the nonradiative relaxations, we observed the heating of the nanoparticles (22 °C to 240 °C) with subsequent thermal enhancement of the frequency UCs due to the redistribution of population among coupled energy levels of the Nd$^{3+}$ ions.
Analysis of Marketing Margins under Food Recalls and BSE Outbreaks in the U.S. Beef Industry
Creators: name: Dhoubhadel, Sunil P.
name: Castillo, Sergio C.
name: Capps, Oral
name: Dhoubhadel, Sunil P.
name: Castillo, Sergio C.
name: Capps, Oral
Publisher: name: Unknown
Year: 2009
Subjects: subject: Agribusiness
subject: Demand and Price Analysis
subject: Marketing
subject: FOS: Economics and business
subject: marketing margins
subject: elasticities of price transmission
subject: BSE
subject: food recalls
subject: U.S. beef industry

description: It is generally observed that whenever there are cases of disease outbreaks or food recalls, there is a concomitant decline in commodity prices. However, it is still not clear what happens to price spreads among affected agents in the marketing chain. To shed light on this issue, we estimate the collective impact of Bovine Spongiform Encephalopathy (BSE) and food recalls on marketing margins associated with the U.S. beef industry over time. In previous research, the effects of these variables on the market demand of meat were estimated separately. By including these variables together in the same model specification we avoid the possibility of confounding their effects, and we are in position to obtain more precise estimates of elasticities of price transmission along the marketing chain.
Methods in causal inference. Part 4: confounding in experiments
Creators: name: Bulbulia, Joseph
Publisher: name: Open Access Te Herenga Waka-Victoria University of Wellington
Year: 2025
Subjects: classificationCode: 44
subject: Human society
classificationCode: 43
subject: History, heritage and archaeology
classificationCode: 4301
subject: Archaeology
classificationCode: 4401
subject: Anthropology
subject: FOS: Sociology

description: Confounding bias arises when a treatment and outcome share a common cause. In randomised controlled experiments (trials), treatment assignment is random, ostensibly eliminating confounding bias. Here, we use causal directed acyclic graphs to unveil eight structural sources of bias that nevertheless persist in these trials. This analysis highlights the crucial role of causal inference methods in the design and analysis of experiments, ensuring the validity of conclusions drawn from experimental data.