Ion-implantation-caused special damage profiles determined by spectroscopic ellipsometry in crystalline and in relaxed (annealed) amorphous silicon

We previously developed a fitting method of several parameters to evaluate ion-implantation-caused damage profiles from spectroscopic ellipsometry (SE) (M. Fried et al., J. Appl. Phys., 71 (1992) 2835). Our optical model consists of a stack of layers with fixed and equal thicknesses and damage levels described by a depth profile function (coupled half Gaussians). The complex refractive index of each layer is calculated from the actual damage level by Bruggeman effective medium approximation (EMA) using crystalline (c-Si) and amorphous (a-Si) silicon as end-points. Two examples are presented of the use of this method with modified optical models. First, we investigated the surface damage formed by room temperature B+ and N+ implantation into silicon. For the analysis of the SE data we added a near surface amorphous layer to the model with variable thickness. Second, we determined 20 keV B+ implantation-caused damage profiles in relaxed (annealed) amorphous silicon. In this special case, the complex refractive index of each layer was calculated from the actual damage level by the EMA using relaxed a-Si and implanted a-Si as end-points. The calculated profiles are compared with Monte Carlo simulations (TRIM code); good agreement is obtained

Avaliação da formação de compostos fenólicos em resíduos contendo benzeno após aplicação de processo fenton.

Projeto/Plano de Ação: 16.300.30004-00

Harvest and habitats of Atlantic sturgeon Acipenser oxyrinchus Mitchill, 1815 in the Hudson River estuary: Lessons for sturgeon conservation

Conservation of the Hudson River population of the sturgeon Acipenser oxyrinchus Mitchill, 1815 has benefitted from the most intensive research programme on any population of the species. We review the history of the fishery for A. oxyrinchus in the Hudson River, and concisely summarise diverse research findings on its life history and habitat use. The fishery for A. oxyrinchus from the Hudson River had one period of very high harvest (pre-1900s), a long period (1900-1979) of minimal harvest and slow population recovery, a period (1980-1992) of restored abundance and high harvest, and finally another decline and suspension of fishing (1996). Sturgeon spawning and early juvenile development occurs in the freshwater portion of the Hudson River, whereas adult and large juvenile sturgeon occupy marine waters, and some of these fish will annually occupy low salinity sites in the Hudson River and other coastal rivers in summer. A. oxyrinchus of the Hudson River are genetically distinct from other populations associated with rivers along the Atlantic coast. Eight different habitats are used during the life cycle of Hudson River A. oxyrinchus, and these are described in physical and temporal terms. The history and biology of the Hudson River A. oxyrinchus suggest three lessons for sturgeon restoration: basic life history knowledge is essential, fishery management is difficult, and regular population monitoring will be needed from the start.La conservación de la población del río Hudson de esturión Acipenser oxyrinchus Mitchill, 1815 se ha beneficiado del programa de investigación más intensivo de los proyectados en la preservación de cualquier otra población de la especie. Se revisa aquí la historia de la pesca de A. oxyrinchus en el río Hudson y se resumen concisamente diversos hallazgos de investigación sobre su historia natural y uso del hábitat. La pesca de A. oxyrinchus en el río Hudson tuvo un periodo de muy alta explotación (antes de 1900), un largo periodo de mínima explotación y lenta recuperación poblacional (1900-1979), un periodo de restauración de abundancia y alta explotación (1980-1992) y, finalmente, otro declive y suspensión de la pesca (1996). La puesta del esturión y el desarrollo temprano de los juveniles tienen lugar en el tramo de agua dulce del río Hudson, mientras los adultos y los juveniles grandes ocupan aguas marinas; algunos de estos peces ocuparán anualmente, en verano, lugares de baja salinidad en el Hudson y en otros ríos costeros. La población de A. oxyrinchus del río Hudson es distinta genéticamente de otras poblaciones asociadas con ríos a lo largo de la costa atlántica. Durante su ciclo vital, el A. oxyrinchus del río Hudson utiliza ocho diferentes hábitats, que son descritos en términos físicos y temporales. La historia y la biología de esta especie del río Hudson sugieren tres lecciones para la restauración de los esturiones: es imprescindible el conocimiento básico de la historia natural, la gestión de la pesca es difícil y el seguimiento regular de la población será necesario desde el principio.Instituto Español de Oceanografí

Gyrification in relation to cortical thickness in the congenitally blind

Greater cortical gyrification (GY) is linked with enhanced cognitive abilities and is also negatively related to cortical thickness (CT). Individuals who are congenitally blind (CB) exhibits remarkable functional brain plasticity which enables them to perform certain non-visual and cognitive tasks with supranormal abilities. For instance, extensive training using touch and audition enables CB people to develop impressive skills and there is evidence linking these skills to cross-modal activations of primary visual areas. There is a cascade of anatomical, morphometric and functional-connectivity changes in non-visual structures, volumetric reductions in several components of the visual system, and CT is also increased in CB. No study to date has explored GY changes in this population, and no study has explored how variations in CT are related to GY changes in CB. T1-weighted 3D structural magnetic resonance imaging scans were acquired to examine the effects of congenital visual deprivation in cortical structures in a healthy sample of 11 CB individuals (6 male) and 16 age-matched sighted controls (SC) (10 male). In this report, we show for the first time an increase in GY in several brain areas of CB individuals compared to SC, and a negative relationship between GY and CT in the CB brain in several different cortical areas. We discuss the implications of our findings and the contributions of developmental factors and synaptogenesis to the relationship between CT and GY in CB individuals compared to SC. F

Influence of Combined Tension and Torsion on the Performance of REBCO Superconducting Tapes

Rare-earth-barium-copper-oxide (REBCO) coated conductor tapes are promising materials for superconducting cables and wires. Simulation studies of the impact of the mechanical loading on the degradation of superconducting tapes give a better understanding on the role of different geometrical parameters like tape width and thicknesses of constituent layers. In this article, a detailed analysis of combined tensile and torsional loading on REBCO tape is carried out. The results show that the thickness of each constituting layer of the tape influences the ability of the tape to withstand tensile and torsional loads. Although increasing the width of the tape increases the maximum allowable tensile load, it decreases its ability to withstand the torsional load. The angle of twist is increased from 0.18 to 0.72 °/mm, and the maximum applied tensile strain that can be applied is decreased from 0.65% to 0.3%. The maximum allowable angle of twist is decreased from 4 to 0.93 °/mm with the increase in the tape width from 3 to 12 mm under pure torsion. The critical current retention capacity of the tape changes with different geometric parameters of the tape. The findings are useful in determining appropriate values for the thicknesses of each layer and width of the tape corresponding to the magnitude of pure tensile, pure torsional and combined tensile and torsional loads experienced.</p