Study of pinholes and nanotubes in AlInGaN films by cathodoluminescence and atomic force microscopy

Cathodoluminescence (CL) in the scanning electron microscope and atomic force microscopy (AFM) have been used to study the formation of pinholes in tensile and compressively strained AlInGaN films grown on Al2O3 substrates by plasma-induced molecular beam epitaxy. Nanotubes, pits, and V-shaped pinholes are observed in a tensile strained sample. CL images show an enhanced emission around the pits and a lower intensity at the V-shaped pinholes. Rounded pinholes appear in compressively strained samples in island-like regions with higher In concentration. The grain structure near the pinholes is resolved by AFM. (C) 2004 American Institute of Physics

One-loop Yukawas on Intersecting Branes

We calculate Yukawa interactions at one-loop on intersecting D6 branes. We demonstrate the non-renormalization theorem in supersymmetric configurations, and show how Yukawa beta functions may be extracted. In addition to the usual logarithmic running, we find the power-law dependence on the infra-red cut-off associated with Kaluza-Klein modes. Our results may also be used to evaluate coupling renormalization in non-supersymmetric cases.Comment: 48 pages, 9 figures; minor corrections, JHEP styl

Differences in Closed-Loop Control of Cutting Movements Between Collegiate Athletes and Non-Athletes

Background: The ability of athletes to make quick adaptations or adjustments in their movement is based on the closed-loop control system. One area of interest in athletic performance is the ability for athletes to perform cutting movements in unpredictable environments. Objective: To determine the interactions of two groups of participants and cutting angles in vertical ground reaction forces (GRFs) and time of foot contact in a closed-loop environment. The study also compared the two given time-frames to process feedback between athletes and non-athletes. Design and Setting: Measurements of the time of foot contact and the active vertical GRF were recorded to compare the movement efficiency. Collegiate athletes and healthy young adults were used for base samples. Subjects: Ten participants (5 collegiate soccer players and 5 healthy young adults) volunteered. Measurements: The time of foot contact and the active vertical GRF were measured in a total of 8 trials in 4 different angles and two different time-frame conditions. Data were analyzed using two 2*4 mixed-design ANOVA, p< 0.05. Results: The athletes performed higher active vertical GRF in the shorter time of foot contact, compared to the non-athletes. The results did not show significant interaction

COMPARISON IN FORCE GENERATION AND TIME OF FOOT CONTACT IN FOUR DIFFERENT CUTTING ANGLES BETWEEN ATHLETES AND NON-ATHLETES

The purpose of this study was to determine the differences in peak active vertical ground reaction force (vGRF) and time of foot contact in four different cutting angles of a closed-loop situation between two groups. A total of 10 participants (n=5, athletes, n=5, non-athletes) ran across a force plate to measure peak active vGRF and time of foot contact in four different angles. Data were analyzed using two 2x4 mixed-design ANOVA (

Faustino Miranda (1905-1964). Nuevos datos relacionados con su formación botánica en España y con su contribución a la Ficología marina.

DOSIL MANCILLA, F. J.; CREMADES UGARTE, J. & FRAGA VÁZQUEZ, X. A. 2001. Faustino Miranda (1905-1964). Nuevos datos relacionados con su formación botánica en España y con su contribución a la Ficología marina. Bot. Complutensis 25: 191-205. Se presentan aspectos relevantes poco conocidos de la actividad ficológica de Faustino Miranda, en particular de su período de formación en Francia, en donde pudo trabajar con destacados ficólogos, y de la actividad que desarrolló en la Estación de Biología marina de Marín (Pontevedra), impartiendo los primeros cursos de Ficología marina en España e investigando en la flora marina de las Rías Baixas gallegas. Estos datos subrayan la excelente preparación del ficólogo y su papel en la institucionalización de esta disciplina en España. La Guerra Civil frustró estas halagüeñas expectativas, obligando al botánico a trasladarse a México.DOSIL MANCILLA, F. J., CREMADES UGARTE, J. & FRAGA VÁZQUEZ, X. A. 2001. Faustino Miranda (1905-1964). New data about his botanical formation in Spain and his marine Phycology contribution. Bot. Complutensis 25: 191-205. Aspects bad-known of Faustino Miranda's phycological activity are developed in this paper. We analyse his formation period in France, where he could work with prominent phycologist, and the activity that Miranda developed in the Station of marine biology of Marin (Pontevedra), where he teached first phycologist course in Spain, and where he could investigate about the Galician marine flore. These dates remark his excelent preparation as phycology and his key paper in the spanish phycologist institucionalitation. The Civil War (1936-39) frustrated these hopes and Miranda must exile at Mexico. 191 F. J. Dosil Mancilla et al. Faustino Miranda (1905-1964)..

An Asymmetric Cone Model for Halo Coronal Mass Ejections

Due to projection effects, coronagraphic observations cannot uniquely determine parameters relevant to the geoeffectiveness of CMEs, such as the true propagation speed, width, or source location. The Cone Model for Coronal Mass Ejections (CMEs) has been studied in this respect and it could be used to obtain these parameters. There are evidences that some CMEs initiate from a flux-rope topology. It seems that these CMEs should be elongated along the flux-rope axis and the cross section of the cone base should be rather elliptical than circular. In the present paper we applied an asymmetric cone model to get the real space parameters of frontsided halo CMEs (HCMEs) recorded by SOHO/LASCO coronagraphs in 2002. The cone model parameters are generated through a fitting procedure to the projected speeds measured at different position angles on the plane of the sky. We consider models with the apex of the cone located at the center and surface of the Sun. The results are compared to the standard symmetric cone model

Floristic study of a maërl and gravel subtidal bed in the ‘Ría de Arousa´ (Galicia, Spain)

Se presenta un catalogo de 68 especies de las algas marinas existentes en un banco de maerl y cascajo de la ria de Arousa (Galicia,Espana). Colacodictyon reticulatum y Gelidiella calcicola son novedad para la Peninsula Iberica. Otras especies de interes sBárbara, I.; Cremades, J. & Veiga, A. J. 2004. Floristic study of a maërl and gravel subtidal bed in the `Ría de Arousa' (Galicia, Spain). Bot. Complut. 28: 27-37. A catalogue of 68 species of seaweeds associated with a subtidal maërl and gravel bed in the «Arousa Ría» (Galicia, Spain) is presented. Colacodictyon reticulatum and Gelidiella calcicola are new for the Iberian Peninsula. Other interesting species are Stylonema cornu-cervi, Cruoria rosea-stage, C. cruoriaeformis, Trailliella intricata-stage, Hymenoclonium serpens-stage, Dasya punicea, Heterosiphonia japonica, Symphyocarpus strangulans and Desmarestia dudresnayi. In Dasya punicea spermatangial stichidia are described for the first time. Seasonal floristic variations in the subtidal maërl and gravel bed are described. Species adapted to this biogenic, unstable substratum with crustose or prostrate forms, like Cruoria cruoriaeformis, C. rosea-stage, Peyssonnelia dubyi, Symphyocarpus strangulans, Aglaozonia parvula-stage and Gelidiella calcicola, are abundant. The vegetation exhibits prominent seasonal variations: in winter the vegetation remains dormant (as crustose growth forms) but in summer produces erect foliose thalli. The alternation of these biological stages has heteromorphic cycles in which the crustose stages provide constant populations during the unfavourable season and the later development of the erect phase of species

Coisotropic D8-branes and Model-building

Up to now chiral type IIA vacua have been mostly based on intersecting D6-branes wrapping special Lagrangian 3-cycles on a CY three-fold. We argue that there are additional BPS D-branes which have so far been neglected, and which seem to have interesting model-building features. They are coisotropic D8-branes, in the sense of Kapustin and Orlov. The D8-branes wrap 5-dimensional submanifolds of the CY which are trivial in homology, but contain a worldvolume flux that induces D6-brane charge on them. This induced D6-brane charge not only renders the D8-brane BPS, but also creates D=4 chirality when two D8-branes intersect. We discuss in detail the case of a type IIA Z2 x Z2 orientifold, where we provide explicit examples of coisotropic D8-branes. We study the chiral spectrum, SUSY conditions, and effective field theory of different systems of D8-branes in this orientifold, and show how the magnetic fluxes generate a superpotential for untwisted Kahler moduli. Finally, using both D6-branes and coisotropic D8-branes we construct new examples of MSSM-like type IIA vacua.Comment: 63 pages, 11 figures. Typos corrected and comments adde

Integrated electromyogram and eye-gaze tracking cursor control system for computer users with motor disabilities

This research pursued the conceptualization, implementation, and testing of a system that allows for computer cursor control without requiring hand movement. The target user group for this system are individuals who are unable to use their hands because of spinal dysfunction or other afflictions. The system inputs consisted of electromyogram (EMG) signals from muscles in the face and point-of-gaze coordinates produced by an eye-gaze tracking (EGT) system. Each input was processed by an algorithm that produced its own cursor update information. These algorithm outputs were fused to produce an effective and efficient cursor control. Experiments were conducted to compare the performance of EMG/EGT, EGT-only, and mouse cursor controls. The experiments revealed that, although EMG/ EGT control was slower than EGT-only and mouse control, it effectively controlled the cursor without a spatial accuracy limitation and also facilitated a reliable click operation

TeV-Scale Z' Bosons from D-branes

Generic D-brane string models of particle physics predict the existence of extra U(1) gauge symmetries beyond hypercharge. These symmetries are not of the E_6 class but rather include the gauging of Baryon and Lepton numbers as well as certain Peccei-Quinn-like symmetries. Some of the U(1)'s have triangle anomalies, but they are cancelled by a Green-Schwarz mechanism. The corresponding gauge bosons typically acquire a mass of order the string scale M_S by combining with two-index antisymmetric fields coming from the closed string sector of the theory. We argue that in string models with a low string scale M_S proportional to 1-10 TeV, the presence of these generic U(1)'s may be amenable to experimental test. Present constraints from electroweak precision data already set important bounds on the mass of these extra gauge bosons. In particular, for large classes of models, rho-parameter constraints imply M_S >= 1.5 TeV. In the present scheme some fraction of the experimentally measured Z^0 mass would be due not to the Higgs mechanism, but rather to the mixing with these closed string fields. We give explicit formulae for recently constructed classes of intersecting D6- and D5-brane models yielding the Standard Model (SM) fermion spectrum.Comment: 46 pages, LaTeX, JHEP.cls, 21 Figures. minor correction