Observation of a Nuclear Recoil Peak at the 100 eV Scale Induced by Neutron Capture.

Coherent elastic neutrino-nucleus scattering and low-mass dark matter detectors rely crucially on the understanding of their response to nuclear recoils. We report the first observation of a nuclear recoil peak at around 112 eV induced by neutron capture. The measurement was performed with a CaWO_{4} cryogenic detector from the NUCLEUS experiment exposed to a ^{252}Cf source placed in a compact moderator. We identify the expected peak structure from the single-γ de-excitation of ^{183}W with 3σ and its origin by neutron capture with 6σ significance. This result demonstrates a new method for precise, in situ, and nonintrusive calibration of low-threshold experiments.

Density gradient stabilization of electron temperature gradient driven turbulence in a spherical tokamak.

In this Letter we report the first clear experimental observation of density gradient stabilization of electron temperature gradient driven turbulence in a fusion plasma. It is observed that longer wavelength modes, k(⊥)ρ(s) ≲ 10, are most stabilized by density gradient, and the stabilization is accompanied by about a factor of 2 decrease in the plasma effective thermal diffusivity.

Suppression of electron temperature gradient turbulence via negative magnetic shear in NSTX.

Negative magnetic shear is found to suppress electron turbulence and improve electron thermal transport for plasmas in the National Spherical Torus Experiment (NSTX). Sufficiently negative magnetic shear results in a transition out of a stiff profile regime. Density fluctuation measurements from high-k microwave scattering are verified to be the electron temperature gradient (ETG) mode by matching measured rest frequency and linear growth rate to gyrokinetic calculations. Fluctuation suppression under negligible E×B shear conditions confirm that negative magnetic shear alone is sufficient for ETG suppression. Measured electron temperature gradients can significantly exceed ETG critical gradients with ETG mode activity reduced to intermittent bursts, while electron thermal diffusivity improves to below 0.1 electron gyro-Bohms.

Observations of reduced electron Gyroscale fluctuations in national spherical torus experiment H-mode plasmas with large ExB flow shear.

Electron gyroscale fluctuation measurements in National Spherical Torus Experiment H-mode plasmas with large toroidal rotation reveal fluctuations consistent with electron temperature gradient (ETG) turbulence. Large toroidal rotation in National Spherical Torus Experiment plasmas with neutral beam injection generates ExB flow shear rates comparable to ETG linear growth rates. Enhanced fluctuations occur when the electron temperature gradient is marginally stable with respect to the ETG linear critical gradient. Fluctuation amplitudes decrease when the ExB flow shear rate exceeds ETG linear growth rates. The observations indicate that ExB flow shear can be an effective suppression mechanism for ETG turbulence.

Correlation between electron transport and shear Alfvén activity in the National Spherical Torus Experiment.

We report the observation of a correlation between shear Alfvén eigenmode activity and electron transport in plasma regimes where the electron temperature gradient is flat, and thus the drive for temperature gradient microinstabilities is absent. Plasmas having rapid central electron transport show intense, broadband global Alfvén eigenmode (GAE) activity in the 0.5-1.1 MHz range, while plasmas with low transport are essentially GAE-free. The first theoretical assessment of a GAE-electron transport connection indicates that overlapping modes can resonantly couple to the bulk thermal electrons and induce their stochastic diffusion.

Retrospective analysis of leg ulcers casesat the university hospital, Faculty ofMedicine of Ribeirão Preto, Universityof São Paulo (1991-2001)

Introduction: Leg ulcers are a syndrome characterized by loss of tegument that affect the lower extremities usually caused by vascular systemdysfunction, representing a high morbidity chronic disease especially among the aged. This study determined the epidemiological characteristics ofleg ulcer patients seen at Clinical Hospital Ribeirão Preto from 1991 to 2001, and their main etiologies and the resolving nature of the treatmentsapplied were investigated.Method: This was a descriptive retrospective study (case series) analyzing 199 medical records of leg ulcer patients, coded by the Medical Recordsfrom 1991 to 2001.Results: 51% of the patients were women and 49% men, with respective median ages of 65 and 66 years, and 81% were white. Etiologically, 49%were classified as venous ulcers, 15% arterial, 9% neuropathic, 2% anemic, and 20% were not classified. Approximately 40% of the patients hadbeen wounded for more than 1 year, 13% died, 40% discharged, and 45% evolved with chronic disease. Among the discharged patients, 64% ofthose with arterial ulcers and 80% of those with neurotrophic ulcers underwent amputation of the segment involved. Regarding venous ulcers, only37% of the patients were discharged, after local dressing in 56% of cases and after skin graft in only one.Comment: Leg ulcer disease was found to be an important chronic disease among the patients seen at the Clinical Hospital Ribeirão Preto from 1991to 2001, with severe consequences regarding the arterial and neurotrophic ulcers, although the etiologic diagnosis was unknown or neglected in20.1% of the cases (AU)

Introdução: Úlcera de perna é uma síndrome caracterizada por perda circunscrita ou irregular do tegumento, que acomete extremidades dos membrosinferiores cuja causa geralmente está na disfunção do sistema vascular. Doença crônica de alta morbidade principalmente na população idosa. Oestudo busca características epidemiológicas dos pacientes com úlceras de perna atendidos no Hospital das Clínicas de Ribeirão Preto, de 1991 a2001, conhecer suas principais etiologias e a resolubilidade dos tratamentos realizados.Metodologia: Estudo descritivo e retrospectivo (série de casos), da análise de 199 prontuários médicos dos pacientes com úlceras de perna, codificadospelo Arquivo Médico, de 1991 a 2001.Leg ulcers are a syndrome characterized by the circumscribedor irregular loss of tegument (dermis or epidermis)that may reach subcutaneous tissue and underlying tissues.The disease involves the lower extremities and thecause usually is related to some dysfunction of the arterialor venous vascular system.[1] The classification may bebased on etiology and therefore leg ulcers are divided intothose due to venous insufficiency (venous ulcers), to arterialinsufficiency (arterial ulcers), to neuropathy (neuropathiculcer/diabetic foot), to red blood cell abnormalities(anemic ulcers), to obliterating thromboangiitis, as well asthose due to causes such as trauma, neoplasia, infections,panniculitis, and pyoderma gangrenosum.[1-4] Among themain predisposing factors are age (elderly individuals), sex(females), obesity, profession (prolonged standing up), vulnerabilityof the legs to traumas and infections, (..) (AU)

Short-scale turbulent fluctuations driven by the electron-temperature gradient in the national spherical torus experiment.

Measurements with coherent scattering of electromagnetic waves in plasmas of the National Spherical Torus Experiment indicate the existence of turbulent fluctuations in the range of wave numbers k perpendicular rho(e)=0.1-0.4, corresponding to a turbulence scale length nearly equal to the collisionless skin depth. Experimental observations and agreement with numerical results from a linear gyrokinetic stability code support the conjecture that the observed turbulence is driven by the electron-temperature gradient.

A collective scattering system for measuring electron gyroscale fluctuations on the National Spherical Torus Experiment.

A collective scattering system has been installed on the National Spherical Torus Experiment (NSTX) to measure electron gyroscale fluctuations in NSTX plasmas. The system measures fluctuations with k( perpendicular)rho(e) less, similar0.6 and k( perpendicular) less, similar20 cm(-1). Up to five distinct wavenumbers are measured simultaneously, and the large toroidal curvature of NSTX plasmas provides enhanced spatial localization. Steerable optics can position the scattering volume throughout the plasma from the magnetic axis to the outboard edge. Initial measurements indicate rich turbulent dynamics on the electron gyroscale. The system will be a valuable tool for investigating the connection between electron temperature gradient turbulence and electron thermal transport in NSTX plasmas.

Observation of high-field-side crash and heat transfer during sawtooth oscillation in magnetically confined plasmas.

High resolution (temporal and spatial), two-dimensional images of electron temperature fluctuations during sawtooth oscillations were employed to study the crash process and heat transfer in magnetically confined toroidal plasmas. The combination of kink and local pressure driven instabilities leads to a small poloidally localized puncture in the magnetic surface at both the low and the high field sides of the poloidal plane. This observation closely resembles the "fingering event" of the ballooning mode model with the high- mode only predicted at the low field side.

Comparison study of 2D images of temperature fluctuations during sawtooth oscillation with theoretical models.

High temporal and spatial resolution two-dimensional (2D) images of electron temperature fluctuations were employed to study the sawtooth oscillation in the Toroidal Experiment for Technically Oriented Research tokamak plasmas. The 2D images are directly compared with the expected 2D patterns of the plasma pressure (or electron temperature) from various theoretical models. The observed experimental 2D images are only partially in agreement with the expected patterns from each model: The image of the initial reconnection process is similar to that of the ballooning mode model. The intermediate and final stages of the reconnection process resemble those of the full reconnection model. The time evolution of the images of the hot spot or island is partially consistent to those from the full reconnection model but is not consistent with those from the quasi-interchange model.

Nature of monster sawteeth and their relationship to Alfven instabilities in tokamaks

A correlation is explored between the presence of energetic particle modes (EPM) and long-period sawtooth oscillations in tokamak plasmas heated by rf waves. The eventual crash of these sawteeth is explained in terms of the loss of the stabilizing fast particles due to the EPM. The absence of long-period sawteeth in high q(a) discharges is explained in terms of ion loss due to toroidal Alfven eigenmodes.