Non-invasive vibrational mode spectroscopy of ion Coulomb crystals through resonant collective coupling to an optical cavity field

We report on a novel non-invasive method to determine the normal mode frequencies of ion Coulomb crystals in traps based on the resonance enhanced collective coupling between the electronic states of the ions and an optical cavity field at the single photon level. Excitations of the normal modes are observed through a Doppler broadening of the resonance. An excellent agreement with the predictions of a zero-temperature uniformly charged liquid plasma model is found. The technique opens up for investigations of the heating and damping of cold plasma modes, as well as the coupling between them.Comment: 4 pages, 4 figure

Collective strong coupling between ion Coulomb crystals and an optical cavity field: Theory and experiment

A detailed description and theoretical analysis of experiments achieving coherent coupling between an ion Coulomb crystal and an optical cavity field are presented. The various methods used to measure the coherent coupling rate between large ion Coulomb crystals in a linear quadrupole radiofrequency ion trap and a single field mode of a moderately high-finesse cavity are described in detail. Theoretical models based on a semiclassical approach are applied in assessment of the experimental results of [P. F. Herskind et al., Nature Phys. 5, 494 (2009)] and of complementary new measurements. Generally, a very good agreement between theory and experiments is obtained.Comment: 15 pages, 15 figure

Anxious to see you: Neuroendocrine mechanisms of social vigilance and anxiety during adolescence.

Social vigilance is a behavioral strategy commonly used in adverse or changing social environments. In animals, a combination of avoidance and vigilance allows an individual to evade potentially dangerous confrontations while monitoring the social environment to identify favorable changes. However, prolonged use of this behavioral strategy in humans is associated with increased risk of anxiety disorders, a major burden for human health. Elucidating the mechanisms of social vigilance in animals could provide important clues for new treatment strategies for social anxiety. Importantly, during adolescence the prevalence of social anxiety increases significantly. We hypothesize that many of the actions typically characterized as anxiety behaviors begin to emerge during this time as strategies for navigating more complex social structures. Here, we consider how the social environment and the pubertal transition shape neural circuits that modulate social vigilance, focusing on the bed nucleus of the stria terminalis and prefrontal cortex. The emergence of gonadal hormone secretion during adolescence has important effects on the function and structure of these circuits, and may play a role in the emergence of a notable sex difference in anxiety rates across adolescence. However, the significance of these changes in the context of anxiety is still uncertain, as not enough studies are sufficiently powered to evaluate sex as a biological variable. We conclude that greater integration between human and animal models will aid the development of more effective strategies for treating social anxiety

Stroke outcome in clinical trial patients deriving from different countries

<p><b>Background and Purpose:</b> Stroke incidence and outcome vary widely within and across geographical locations. We examined whether differences in index stroke severity, stroke risk factors, mortality, and stroke outcome across geographical locations remain after adjusting for case mix.</p> <p><b>Methods:</b> We analyzed 3284 patients from the Virtual International Stroke Trials Archive (VISTA). We used logistic regression to examine the incidence of mild index stroke, functional, and neurological outcomes after accounting for age, medical history, year of trial recruitment, and initial stroke severity in the functional and neurological outcome analyses. We examined mortality between geographical regions using a Cox proportional hazards model, accounting for age, initial stroke severity, medical history, and year of trial recruitment.</p> <p><b>Results</b> Patients enrolled in the USA and Canada had the most severe index strokes. Those recruited in Austria and Switzerland had the best functional and neurological outcomes at 90 days (P<0.05), whereas those enrolled in Germany had the worst functional outcome at 90 days (P=0.013). Patients enrolled in Austria, Switzerland, Belgium, Netherlands, Finland, Germany, Greece, Israel, Spain, and Portugal had a significantly better survival rate when compared with those enrolled in USA and Canada. Patients enrolled in trials after 1998 had more severe index strokes, with no significant difference in outcome compared with those enrolled before 1998.</p> <p><b>Conclusion:</b> We identified regional variations in index stroke severity, outcome, and mortality for patients enrolled in ischemic stroke clinical trials over the past 13 years that were not fully explained by case mix. Index stroke severity was greater in patients enrolled after 1998, with no significant improvement in outcomes compared to those enrolled before 1998.</p&gt

Mycorrhizae Indirectly Enhance Competitive Effects of an Invasive Forb on a Native Bunchgrass

Mycorrhizae are important mediators of plant competition, but little is known about the role of mycorrhizae in the intense competitive effects that exotic plants can have on native species. In the greenhouse, we tested the effect of arbuscular mycorrhizal (AM) fungi on interspecific competition between Centaurea maculosa and Festuca idahoensis, on intraspecific competition between individuals of both species, and the growth of C. maculosa with either inorganic or organic phosphorus. Mycorrhizae had no direct effect on either species, but mycorrhizae increased C. maculosa\u27s negative effect on F. idahoensis. When competing with C. maculosa, nonmycorrhizal F. idahoensis were 171% larger than they were when mycorrhizae were present. In a second experiment, C. maculosa grown with larger F. idahoensis were 66% larger, in the presence of AM fungi, than when AM fungi were absent. Centaurea maculosa biomass was not affected by AM fungi, in either phosphorus treatment, in the absence of F. idahoensis. Root:shoot ratios differed between phosphorus treatments, but this difference seemed to be a result of slower growth in the organic phosphorus treatment. Our results were unusual in that the direct effects of mycorrhizae on both species were weak, but the indirect effect of AM fungi on the interactions between C. maculosa and F. idahoensis was strong. Our results suggest that AM fungi strongly enhance the ability of C. maculosa to invade native grasslands of western North America

Germanium Detector with Internal Amplification for Investigation of Rare Processes

Device of new type is suggested - germanium detector with internal amplification. Such detector having effective threshold about 10 eV opens up fresh opportunity for investigation of dark matter, measurement of neutrino magnetic moment, of neutrino coherent scattering at nuclei and for study of solar neutrino problem. Construction of germanium detector with internal amplification and perspectives of its use are described.Comment: 13 pages, latex, 3 figures, report at NANP-99, International Conference on Non-Accelerator Physics, Dubna, Russia, June 29- July 3, 1999. To be published in the Proceeding