Spontaneous soliton formation and modulational instability in Bose-Einstein condensates

The dynamics of an elongated attractive Bose-Einstein condensate in an axisymmetric harmonic trap is studied. It is shown that density fringes caused by self-interference of the condensate order parameter seed modulational instability. The latter has novel features in contradistinction to the usual homogeneous case known from nonlinear fiber optics. Several open questions in the interpretation of the recent creation of the first matter-wave bright soliton train [Strecker {\it et al.} Nature {\bf 417} 150 (2002)] are addressed. It is shown that primary transverse collapse, followed by secondary collapse induced by soliton--soliton interactions, produce bursts of hot atoms at different time scales.Comment: 4 pages, 3 figures. Phys. Rev. Lett. in pres

Constant Size Molecular Descriptors For Use With Machine Learning

A set of molecular descriptors whose length is independent of molecular size is developed for machine learning models that target thermodynamic and electronic properties of molecules. These features are evaluated by monitoring performance of kernel ridge regression models on well-studied data sets of small organic molecules. The features include connectivity counts, which require only the bonding pattern of the molecule, and encoded distances, which summarize distances between both bonded and non-bonded atoms and so require the full molecular geometry. In addition to having constant size, these features summarize information regarding the local environment of atoms and bonds, such that models can take advantage of similarities resulting from the presence of similar chemical fragments across molecules. Combining these two types of features leads to models whose performance is comparable to or better than the current state of the art. The features introduced here have the advantage of leading to models that may be trained on smaller molecules and then used successfully on larger molecules.Comment: 18 pages, 5 figure

Workshop on Mars Sample Return Science

Martian magnetic history; quarantine issues; surface modifying processes; climate and atmosphere; sampling sites and strategies; and life sciences were among the topics discussed

Important issues for feminist nutrition research – a case study from the savanna of West Africa

SUMMARY Nutrition education usually aims to change the practices of individual mothers. It may divert attention from real problems, increase anxiety or be dangerously inappropriate. This article argues that nutritionists should work at the community, policy and planning levels to create an environment where good nutrition becomes possible. The author describes her experiences with nutrition education, intersectoral cooperation, and nutritional monitoring. She summarises crucial issues for nutritional research and stresses the importance of learning from the mothers and taking their expressed needs as the major research orientation. RESUMEN Problemas importantes para la investigación de la nutrición feminista. Un estudio de caso en la sabana de Africa Occidental En general, la educación en nutrición intenta cambiar las prácticas de las madres a nivel individual. No obstante, puede distraeer la atencion de los problemas reales, incrementar la ansiedad en incluso resultar peligrosamente inadecuada. Este articulo argumenta que los nutricionistas deberian trabajar en los niveles de comunidad, planificación y politica para crear un ambiente en que la buena nutrición sea factible. La autora describe sus experiencias en educación nutricional, cooperación intersectorial y control de nutrición, resumen problemas cruciales para la investigación en esta área y enfatiza la importancia que tiene el aprender de las madres y adoptar sus necesidades explicitas como la orientación principal en la investigación. RESUMES L'importance de la recherche sur la nutrítion fémìnine: une étude de cas particulier dans la Savane d'Afrique de l'Quest L'enseignement de la nutrition a généralernent pour but de changer les habitudes de chaque mére. Il peut détourner l'attention des vrais problèmes augmenter l'anxiété ou être dangereusement inadéquat. Cet article soutient le fait que les hygiénistes alimentaires devraient tiavailler au niveau de la communauté, de la politique et de la planification afin de créer un environnement favorable a la bonne nutrition. L'auteur décrit ses experiences en ce qui concerne l'enseignement de la nutrition. la coopération íntersectorielle et la contrôle nutritionnel. Elle rèsume les points cruciaux pour les chercheurs en nutrition et souligne l'importance d'apprendre a partir des mères et de prendre leurs besoins comme ligne de conduite principale de la recherche

GRB011211: An alternative interpretation of the optical and X-ray spectra in terms of blueshifts

The redshifts of the gamma ray burst (GRB) GRB 011211 has been determined as 2.14 from several absorption lines seen in the spectrum of its optical afterglow. The spectrum of its X-ray afterglow exhibited several emission lines,and their identification led to a mean redshift 1.862. A supernova model has been proposed based on the redshift of the GRB as 2.141. It is shown here that the redshift interpretation cannot explain the observed spectra, as some serious inconsistencies exist in the process of redshift determinations in spectra of both optical and X-ray afterglows. In view of that, an alternative interpretation of the spectra is presented in terms of blueshifts. Ejection mechanism is proposed as a possible scenario to explain the blueshifted spectrum.Comment: 26 pages, one table; in Canadian Journal of Physics, June 200

The Beginning of the End of the Anthropic Principle

We argue that if string theory as an approach to the fundamental laws of physics is correct, then there is almost no room for anthropic arguments in cosmology. The quark and lepton masses and interaction strengths are determined.Comment: 12 page

Fabrication of low-cost, large-area prototype Si(Li) detectors for the GAPS experiment

A Si(Li) detector fabrication procedure has been developed with the aim of satisfying the unique requirements of the GAPS (General Antiparticle Spectrometer) experiment. Si(Li) detectors are particularly well-suited to the GAPS detection scheme, in which several planes of detectors act as the target to slow and capture an incoming antiparticle into an exotic atom, as well as the spectrometer and tracker to measure the resulting decay X-rays and annihilation products. These detectors must provide the absorption depth, energy resolution, tracking efficiency, and active area necessary for this technique, all within the significant temperature, power, and cost constraints of an Antarctic long-duration balloon flight. We report here on the fabrication and performance of prototype 2"-diameter, 1-1.25 mm-thick, single-strip Si(Li) detectors that provide the necessary X-ray energy resolution of $\sim$4 keV for a cost per unit area that is far below that of previously-acquired commercial detectors. This fabrication procedure is currently being optimized for the 4"-diameter, 2.5 mm-thick, multi-strip geometry that will be used for the GAPS flight detectors.Comment: Accepted for publication at Nuclear Instrumentation and Methods A, 12 pages, 11 figure

Disparities in outcomes of COVID-19 hospitalizations in native American individuals

ObjectivesThis study aimed to investigate COVID-19-related disparities in clinical presentation and patient outcomes in hospitalized Native American individuals.MethodsThe study was performed within 30 hospitals of the Banner Health system in the Southwest United States and included 8,083 adult patients who tested positive for SARS-CoV-2 infection and were hospitalized between 1 March 2020 and 4 September 2020. Bivariate and multivariate analyses were used to assess racial and ethnic differences in clinical presentation and patient outcomes.ResultsCOVID-19-related hospitalizations in Native American individuals were over-represented compared with non-Hispanic white individuals. Native American individuals had fewer symptoms at admission; greater prevalence of chronic lung disease in the older adult; two times greater risk for ICU admission despite being younger; and 20 times more rapid clinical deterioration warranting ICU admission. Compared with non-Hispanic white individuals, Native American individuals had a greater prevalence of sepsis, were more likely to require invasive mechanical ventilation, had a longer length of stay, and had higher in-hospital mortality.ConclusionNative American individuals manifested greater case-fatality rates following hospitalization than other races/ethnicities. Atypical symptom presentation of COVID-19 included a greater prevalence of chronic lung disease and a more rapid clinical deterioration, which may be responsible for the observed higher hospital mortality, thereby underscoring the role of pulmonologists in addressing such disparities