Demonstrating Universal Scaling in Quench Dynamics of a Yukawa One-Component Plasma

The Yukawa one-component plasma (OCP) is a paradigm model for describing plasmas that contain one component of interest and one or more other components that can be treated as a neutralizing, screening background. In appropriately scaled units, interactions are characterized entirely by a screening parameter, $\kappa$. As a result, systems of similar $\kappa$ show the same dynamics, regardless of the underlying parameters (e.g., density and temperature). We demonstrate this behavior using ultracold neutral plasmas (UNP) created by photoionizing a cold ($T\le10$ mK) gas. The ions in UNP systems are well described by the Yukawa model, with the electrons providing the screening. Creation of the plasma through photoionization can be thought of as a rapid quench from $\kappa_{0}=\infty$ to a final $\kappa$ value set by the electron density and temperature. We demonstrate experimentally that the post-quench dynamics are universal in $\kappa$ over a factor of 30 in density and an order of magnitude in temperature. Results are compared with molecular dynamics simulations. We also demonstrate that features of the post-quench kinetic energy evolution, such as disorder-induced heating and kinetic-energy oscillations, can be used to determine the plasma density and the electron temperature.Comment: 10 pages, 12 figures, to be submitted to Physical Review

SOME NEW IDENTITIES FOR THE SECOND COVARIANT DERIVATIVE OF THE CURVATURE TENSOR

In this paper we study the second covariant derivative of Riemannian curvature tensor. Some new identities for the second covariant derivative are given. Namely, identities obtained by cyclic sum with respect to three indices are given. In the first case, two curvature tensor indices and one covariant derivative index participate in the cyclic sum, while in the second case one curvature tensor index and two covariant derivative indices participate in the cyclic sum

Towards logic-based verification of javascript programs

In this position paper, we argue for what we believe is a correct pathway to achieving scalable symbolic verification of JavaScript based on separation logic. We highlight the difficulties imposed by the language, the current state-of-the-art in the literature, and the sequence of steps that needs to be taken. We briefly describe JaVerT, our semiautomatic toolchain for JavaScript verification

Exchange biased anomalous Hall effect driven by frustration in a magnetic kagome lattice.

Co[Formula: see text]Sn[Formula: see text]S[Formula: see text] is a ferromagnetic Weyl semimetal that has been the subject of intense scientific interest due to its large anomalous Hall effect. We show that the coupling of this material's topological properties to its magnetic texture leads to a strongly exchange biased anomalous Hall effect. We argue that this is likely caused by the coexistence of ferromagnetism and geometric frustration intrinsic to the kagome network of magnetic ions, giving rise to spin-glass behavior and an exchange bias

Dispersion of Waves in Relativistic Plasmas with Isotropic Particle Distributions

The dispersion laws of Langmuir and transverse waves are calculated in the relativistic non-magnetized formalism for several isotropic particle distributions: thermal, power-law, relativistic Lorentzian $\kappa,$ and hybrid $\beta$. For Langmuir waves the parameters of superluminal undamped, subluminal damped principal and higher modes are determined for a range of distribution parameters. The undamped and principal damped modes are found to match smoothly. Principal damped and second damped modes are found not to match smoothly. The presence of maximum wavenumber is discovered above that no longitudinal modes formally exist. The higher damped modes are discovered to be qualitatively different for thermal and certain non-thermal distributions. Consistently with the known results, the Landau damping is calculated to be stronger for non-thermal power-law-like distributions. The dispersion law is obtained for the single undamped transverse mode. The analytic results for the simplest distributions are provided.Comment: 8 pages, 12 figures, accepted by Physics of Plasma

The Role of Aspirin in Preeclampsia Prevention: State of the Art

Introdução: O papel do ácido acetilsalicílico (AAS ou aspirina) na prevenção das complicações associadas à pré-eclâmpsia tem sido objeto de estudos e de controvérsias ao longo de 30 anos. Os primeiros trabalhos de investigação acerca do papel da placenta na génese da pré-eclâmpsia surgiram em finais dos anos 70 e assinalavam um aumento da atividade plaquetária e alteração da síntese das prostaglandinas, como consequência da deficiente adaptação da placenta. Ao longo dos últimos 20 anos do século XX, sucederam-se estudos de investigação acerca do papel profilático da aspirina na redução do risco de pré-eclâmpsia. Material e Métodos: Para analisar os trabalhos publicados sobre o uso da aspirina na prevenção da pré-eclâmpsia, bem como sobre a dose mais adequada e momento de administração, foram consultados apenas estudos prospetivos, revisões sistemáticas e meta-análises através das seguintes fontes pesquisa (PubMed, Cochrane, Embase). Os artigos citados foram considerados os mais relevantes. Os trabalhos foram divididos em dois grupos: no primeiro foram incluídos os trabalhos em que a aspirina era administrada até às 16 semanas e o segundo, com início de administração por um período mais alargado. Resultados e Discussão: No primeiro grupo, com menor número de casos, mas com início mais precoce de administração do fármaco, até às 16 semanas, concluiu-se que a aspirina poderia ter um papel positivo na redução de risco de gravidade da pré-eclâmpsia; o segundo grupo, com maior número de casos nos estudos, mas com condições menos restritas de entrada e de tempo de início do fármaco, teve resultados mais controversos. As meta-análises destes estudos concluíram que os resultados favoráveis estavam associados às condições de e momento da administração. Conclusão: Não existindo ainda alternativas ou fármacos que lhe possam ser associados, a aspirina em baixas doses (80 a 150 mg/dia) ao deitar, iniciada no 1º trimestre e até às 16 semanas mantém-se um fármaco seguro, que tem contribuído para redução do risco de pré-eclâmpsia precoce, com as consequências que lhe estão associadas

A zone of preferential ion heating extends tens of solar radii from Sun

The extreme temperatures and non-thermal nature of the solar corona and solar wind arise from an unidentified physical mechanism that preferentially heats certain ion species relative to others. Spectroscopic indicators of unequal temperatures commence within a fraction of a solar radius above the surface of the Sun, but the outer reach of this mechanism has yet to be determined. Here we present an empirical procedure for combining interplanetary solar wind measurements and a modeled energy equation including Coulomb relaxation to solve for the typical outer boundary of this zone of preferential heating. Applied to two decades of observations by the Wind spacecraft, our results are consistent with preferential heating being active in a zone extending from the transition region in the lower corona to an outer boundary 20-40 solar radii from the Sun, producing a steady state super-mass-proportional $\alpha$-to-proton temperature ratio of $5.2-5.3$. Preferential ion heating continues far beyond the transition region and is important for the evolution of both the outer corona and the solar wind. The outer boundary of this zone is well below the orbits of spacecraft at 1 AU and even closer missions such as Helios and MESSENGER, meaning it is likely that no existing mission has directly observed intense preferential heating, just residual signatures. We predict that {Parker Solar Probe} will be the first spacecraft with a perihelia sufficiently close to the Sun to pass through the outer boundary, enter the zone of preferential heating, and directly observe the physical mechanism in action.Comment: 11 pages, 7 figures, accepted for publication in the Astrophysical Journal on 1 August 201

A new technique for the reconstruction, validation, and simulation of hits in the CMS Pixel Detector

This note describes new techniques for the reconstruction/validation and the simulation of pixel hits. The techniques are based upon the use of pre-computed projected cluster shapes or ``templates''. A detailed simulation called Pixelav that has successfully described the profiles of clusters measured in beam tests of radiation-damaged sensors is used to generate the templates. Although the reconstruction technique was originally developed to optimally estimate the coordinates of hits after the detector became radiation damaged, it also has superior performance before irradiation. The technique requires a priori knowledge of the track angle which makes it suitable for the second in a two-pass reconstruction algorithm. However, the same modest angle sensitivity allows the algorithm to determine if the sizes and shapes of the cluster projections are consistent with the input angles. This information may be useful in suppressing spurious hits caused by secondary particles and in validating seeds used in track finding. The seed validation is currently under study but has the potential to significantly increase the speed of track finding in the offline reconstruction. Finally, a new procedure that uses the templates to re-weight clusters generated by the CMSSW simulation is described. The first tests of this technique are encouraging and when fully implemented, the technique will enable the fast simulation of pixel hits that have the characteristics of the much more CPU-intensive Pixelav hits. In particular, it may be the only practical technique available to simulate hits from a radiation damaged detector in CMSSW

Quantifying the impact of small scale unmeasured rainfall variability on urban runoff through multifractal downscaling: A case study

International audienceThis paper aims at quantifying the uncertainty on urban runoff associated with the unmeasured small scale rainfall variability, i.e. at a resolution finer than 1. km. ×. 1. km. ×. 5. min which is usually available with C-band radar networks. A case study is done on the 900. ha urban catchment of Cranbrook (London). A frontal and a convective rainfall event are analysed. An ensemble prediction approach is implemented, that is to say an ensemble of realistic downscaled rainfall fields is generated with the help of universal multifractals, and the corresponding ensemble of hydrographs is simulated. It appears that the uncertainty on the simulated peak flow is significant, reaching for some conduits 25% and 40% respectively for the frontal and the convective events. The flow corresponding the 90% quantile, the one simulated with radar distributed rainfall, and the spatial resolution are power law related. © 2012 Elsevier B.V