Análise da viabilidade de simulações com feixes de prótons de 100, 150, 200 e 250 MeV em alvos heterogêneos

In the recent years, the use of proton beams in radiotherapy has been an outstanding progress (SMITH, 2006). Up to now, computed tomography (CT) is a prerequisite for treatment planning in this kind of therapy because it provides the electron density distribution required for calculation of dose and the interval of doses. However, the use of CT images for proton treatment planning ignores fundamental differences in physical interaction processes between photons and protons and is, therefore, potentially inaccurate (SADROZINSKI, 2004). Proton CT (pCT) can in principle directly measure the density distribution needed in a patient for the dose distribution (SCHULTE, et al, 2004). One important problem that should be solved is the implementation of image reconstruction algorithms. In this sense, it is necessary to know how the presence of materials with different density and composition interfere in the energy deposition by ionization and coulomb excitation, during its trajectory. The study was conducted in two stages, was used in both the program SRIM (The Stopping and Range of Ions in Matter) to perform simulations of the interaction of proton beams with pencil beam type. In the first step we used the energies in the range of 100-250 MeV (ZIEGLER, 1999). The targets were set to 50 mm in length for the beam of 100 MeV, due to its interaction with the target, and short-range, and 70 mm for 150, 200 and 250 MeV The target was composed of liquid water and a layer of 6 mm cortical bone (ICRP). It were made 9 simulations varying the position of the heterogeneity of 5 mm. In the second step the energy of 250 MeV was taken out from the simulations, due to its greater energy and less interaction. The targets were diminished to 50 mm thick to standardize the simulations. The layer of bone was divided into two equal parts and both were put in the ends of the target... (Complete abstract click electronic access below)

Digital storytelling at QUT

Digital Storytelling is a powerful means for enabling communication and social participation. Ordinary people work with expert creative practitioners to create first person narratives for a wide and growing range of purposes, including community building, cultural engagement, brand identification and public communication. A digital story usually combines 15-30 still images and a recorded script of 100-250 words to create an original personal digital story in the form of a 2-3 minute digital video. This form of co-creative media takes advantage of newly accessible technologies but is based in the ancient and universal tradition of storytelling. Digital storytelling is being adopted internationally in a variety of institutional contexts. It was introduced at QUT by Distinguished Professor John Hartley in 2004 when he brought well known UK based digital storytelling expert Daniel Meadows to the Creative Industries Faculty to trainer researchers and Faculty in the technique. Since 2005 Creative Industries Faculty researchers have adapted digital storytelling for use in a variety of research contexts including heritage, youth welfare, health, and international development, in collaboration with a range of external partner organisations. More than 300 digital stories have been produced by QUT researchers, staff and students. These have been presented on the World Wide Web, broadcast on community media, released on DVD and exhibited in various forms. In addition CIF researchers have produced numerous journal articles, conference papers and books reporting the outcomes of research projects utilising digital storytelling in research. As a result of research activity the Creative Industries Faculty is now well positioned as a leading site for teaching and learning in digital storytelling. Faculty research activity in digital storytelling has generated interest in adapting the form for use in undergraduate and postgraduate Creative Industries curriculum and in service teaching, including short courses for external clients.

Magnetization process of a single chain of nanomagnets

We have investigated the magnetization reversal process of a single chain of identical nanomagnetic dots fabricated from 30 nm thick Ni 80Fe20. The structures consist of two 5 μm wide support wires bridged with a single chain of identical dots of diameter δ in the range 100-250 nm. For fields applied perpendicular to the single chain, we observed an unusual size dependent hysteretic behavior in the magnetoresistance curve at high field. This is due to the magnetostatic interaction arising from the proximity of the magnetic charges. We are able to deduce from a simple micromagnetic simulation that the reversal process in the chain of dots with δ=100nm is mediated by a collective process of nearly coherent spin rotation. The magnetotransport measurements along the chain reveal a complex magnetization reversal process in the chain of nanomagnets. © 2002 American Institute of Physics.

Response Specificity to Advertisement Vocalization in the Chinese Alligator (Alligator sinensis)

Stringency in the identification of conspecific call properties is essential among sympatric species to ensure conspecific mating, as the risk of improper recognition and heterospecific mating is high. In this study we investigated the basic signal structure required for intraspecies communication in the Chinese alligator (Alligator sinensis), a species that has no relatives living in sympatry, by playback of signals modified in the temporal (truncating original bellows with first 1/4, 1/2, 3/4 or last 1/4, 1/2, 3/4 portion) or frequency domain (with low- or high-pass filters at frequencies 100, 250, 500 and 1000 Hz), or by reversal of natural bellows. The playback experiments revealed that relatively large modifications in bellow temporal or frequency structure failed to impair Chinese alligators' bellowing behavior; even reversed bellows effectively evoked a positive response. In general, the first half of the bellow in temporal domain and frequencies below 500 Hz were critical for behavioral induction, while the last half of the bellow in temporal domain and frequencies above 500 Hz failed to produce a single positive response, implying a potential functional signal redundancy. The observed high tolerance to bellow variations in Chinese alligators may be an evolutionary adaptation to (1) the acoustic constraints of propagation imposed by dense vegetative habitats; or (2) a lack of selection pressure due to the low risk of incorrect conspecific recognition and heterospecific mating.

The fabrication of GaN-based nanopillar light-emitting diodes

InGaN/GaN multiple quantum well-based light-emitting diode (LED) nanopillar arrays were fabricated using Ni self-assembled nanodots as etching mask. The Ni nanodots were fabricated with a density of 6 x 10(8)-1.5 x 10(9) cm(-2) and a dimension of 100-250 nm with varying Ni thickness and annealing duration time. Then LED nanopillar arrays with diameter of approximately 250 nm and height of 700 nm were fabricated by inductively coupled plasma etching. In comparison to the as-grown LED sample an enhancement by a factor of four of photoluminescence (PL) intensity is achieved for the nanopillars and a blueshift as well as a decrease in full width at half maximum of the PL peak are also observed. The method of additional chemical etching was used to remove the etching-induced damage. Then nano-LED devices were further completed using a planarization approach to deposit p-type electrode on the tips of nanopillars. The current-voltage curves of both nanopillars and planar LED devices are measured for comparison.

云南会泽铅锌矿床成矿流体性质和来源—来自流体包裹体和水岩反应实验的证据

位于扬子地块西南缘川、黔、滇铅锌多金属成矿区的中南部的云南会泽铅锌矿床是我国著名的Pb、Zn、Ge生产基地之一，近年来受到很多地质学家和地学工作者的关注。本文在自己研究成果和前人资料的基础上，以云南省会泽铅锌矿床为研究对象，从脉石矿物方解石和脉石矿物热液白云石中的流体包裹体入手，详细研究矿床成矿流体的物理化学条件变化；并结合高温高压实验和前人研究成果（成矿元素分析、同位素等），详细分析该矿床的成矿流体来源、迁移机制与成矿机制，解决矿床成矿流体与围岩、基底、峨眉山玄武岩三者之间的关系，并提出合理的矿床的成因模式；并通过该课题研究，揭示成矿流体随温度、压力变化而变化的规律，了解矿床成矿元素迁移、富集和沉淀的热力学、动力学作用机制，为区域内其他铅锌矿床的找矿和研究提供理论依据。通过系统的研究，获得以下结论和成果： ⑴矿物流体包裹体均一温度主要变化于150~250℃之间，部分包裹体大于300℃；矿床矿物包裹体的形成存在两个高峰期：第一个高峰期包裹体均一温度主要集中于150~220℃，第二个高峰期包裹体均一温度主要集中于300~350℃；包裹体的捕获温度位于150℃~401℃之间，其中大部分高于200℃；盐度变化范围5~21wt% NaCl，平均值为13.24wt% NaCl；密度0.546~1.129 g/cm3；均一瞬间压力145×105Pa ~754×105Pa；成矿过程中流体曾存在沸腾作用和不混溶现象；沸腾包裹体的证据表明，成矿的深度为当时地表以下2200~2450米。因此，矿床成矿流体总体属中温-中压-中等盐度性质。 ⑵H、O同位素计算、流体包裹体、Sr同位素和水-岩反应实验结果表明，矿床成矿流体为不同来源流体混合的产物，具有多源性。而地层成矿元素含量、Pb同位素和水-岩反应实验结果证明成矿物质同样也具有多源性。因此，会泽铅锌矿床的成矿流体、成矿物质都具有多种来源。 ⑶矿床成矿条件：成矿温度为131℃~491℃，平均值为260℃；矿化时间与峨眉山玄武岩岩浆活动的时代较为相近；成矿时流体pH值为4.2~7.5，呈中性~弱碱性；金属矿物的氧逸度主要变化范围为10-55—10-20，硫逸度主要变化范围为10-30—10-10。矿石的品位主要跟流体混合、沸腾作用和断裂带宽度受到限制有关。 ⑷在该矿床，中低温（100~250℃）环境下的铅锌迁移形式有所不同，锌主要以硫氢化物络合物形式进行迁移，兼有少量氯化物络合物；而铅主要以氯化物络合物形式进行迁移，但有部分硫氢化物络合物。而在中高温条件下铅、锌基本都以氯化物络合物的形式进行迁移。影响矿物沉淀的因素很多，但流体混合作用和沸腾作用是引起会泽铅锌矿床金属矿物沉淀的主要原因。 ⑸肉红色白云岩形成的原因可能跟较为封闭的潮坪—泻湖的原始蒸发环境有关；而灰色白云岩则可能来自肉红色白云岩的淋滤交代；白色白云岩的形成则与灰岩、白云质灰岩的热液交代有关。

Modulation of surface charge, particle size and morphological properties of chitosan-TPP nanoparticles intended for gene delivery

This work investigates the polyanion initiated gelation process in fabricating chitosan-TPP (tripolyphosphate) nanoparticles in the size range of 100-250 nm intended to be used as carriers for the delivery of gene or protein macromolecules. It demonstrates that ionic gelation of cationic chitosan molecules offers a flexible and easily controllable process for systematically and predictably manipulating particle size and surface charge which are important properties in determining gene transfection efficacy if the nanoparticles are used as non-viral vectors for gene delivery, or as delivery carriers for protein molecules. Variations in chitosan molecular weight, chitosan concentration, chitosan to TPP weight ratio and solution pH value were examined systematically for their effects on nanoparticle size, intensity of surface charge, and tendency of particle aggregation so as to enable speedy fabrication of chitosan nanoparticles with predetermined properties. The chitosan-TPP nanoparticles exhibited a high positive surface charge across a wide pH range, and the isoelectric point (IEP) of the nanoparticles was found to be at pH 9.0. Detailed imaging analysis of the particle morphology revealed that the nanoparticles possess typical shapes of polyhedrons (e.g., pentagon and hexagon), indicating a similar crystallisation mechanism during the particle formation and growth process. This study demonstrates that systematic design and modulation of the surface charge and particle size of chitosan-TPP nanoparticles can be readily achieved with the right control of critical processing parameters, especially the chitosan to TPP weight ratio. (c) 2005 Elsevier B.V. All rights reserved.

Studies On Mixed Layer Depth In The Arabian Sea

This thesis is the result of an elaborate study on the mixed layer depth (MLD) and the various oceanic environmental factors controlling it in the Arabian Sea examining its predictability on annual and short term basis. To accomplish this, the study area between 100 — 250 N latitudes and 600 — 750 E longitudes in the Arabian Sea is divided into 8 subareas of 50 quadrangles. The distribution of monthly means of the surface wind field, net heat exchange mKi868€%WTmN¥tWMWF3UH9 (SST) over each subarea in the annual cycle is examined. The corresponding wind (mechanical) and convective mixing values are computed and presented along with the observed mean MLD for the subareas in the annual cycle. Effects of advection due to surface currents and surface divergence (convergence and divergence) for these subareas are examined for correlating the MLD variations. A representative time series data from typical deep water station under southwest monsoonal forcing is analysed for the spectral components to estimate the amplitude perturbations on the mean MLD variation

Evaluación educativa mediante pruebas objetivas : desarrollo de nuevos procedimientos de corrección de pruebas y calibración de ítems.

Hacer un estudio comparativo de las distintas pruebas objetivas. Desarrollar procedimientos de estimación del nivel de conocimientos de los examinados y el grado de dificultad de cada ítem, adaptados a las características de cada tipo de prueba. Analizar, comparativamente, las características de las estimaciones procedentes de cada tipo de prueba. Contrastar empíricamente la teoría de estados finitos. 20 simulaciones, correspondientes a la combinación de todos los tipos de prueba y número de ítems: 30, 60, 90, 135, 150 y 225 ítems en pruebas de verdadero-falso. 32 simulaciones, correspondientes a la combinación de todos los tipos de prueba y número de examinados: 50, 100, 250 y 500 examinados contestando a ítems de verdadero-falso. 1090 estudiantes de un curso introductorio de Economía para contrastar empíricamente un modelo de estados finitos. El estudio adopta una teoría psicométrica de estados finitos. Compara pruebas de verdadero-falso con distintos números de ítems con pruebas de elección múltiple con distintos números de ítems y varias alternativas por ítem y administradas bajo diferentes formatos (convencional, Coombs, contestar hasta acertar), incluyendo pruebas con ítems NA (ninguna de las anteriores). Para cada tipo de prueba se elabora un modelo de comportamiento a partir del cual se obtienen estimadores máximo-verosímiles del nivel de conocimientos de los examinados y del grado de dificultad de los ítems. También se llevan a cabo simulaciones con objeto de analizar las características de las estimaciones obtenidas para cada tipo de prueba. Finalmente se contrasta empíricamente un modelo de estados finitos utilizando datos de la administración de una prueba de elección múltiple con ítems NA. Pruebas de verdadero-falso, pruebas de elección múltiple. Parámetros de los examinados, parámetros de los ítems, PC, análisis de residuos, percentiles, fórmulas. Los resultados del análisis comparativo indican claramente la superioridad de las pruebas de verdadero-falso para la estimación de los niveles de conocimiento de los examinados: las estimaciones obtenidas a partir de ellas son más adecuadas que las obtenidas cuando se usan pruebas de elección múltiple con cualquier número de alternativas por ítem y administradas bajo cualquier formato. Por otra parte, con respecto a la calidad de las estimaciones de los grados de dificultad de los ítems, los resultados obtenidos para ítems de verdadero-falso son comparables a los obtenidos para ítems de elección múltiple administrados bajo el formato convencional, en tanto que la administración de las mismas pruebas de elección múltiple bajo formatos alternativos no conduce a mejores estimaciones de los grados de dificultad de los ítems. Los resultados de la contrastación del modelo son positivos, proporcionando evidencia empírica a su favor.

Interações competitivas de triticale (Triticum turgidosecale) e nabiça (Raphanus raphanistrum) em função da população e proporção de plantas

Este trabalho foi realizado com o objetivo de quantificar as interações competitivas e os índices de competitividade entre plantas de triticale e nabiça. A metodologia utilizada foi a de um experimento em monocultura, que variou de 25 a 500 plantas m-2 para determinar o valor a partir do qual a produção se torna independente do aumento da densidade para cada espécie, e um experimento substitutivo, com população total de 300 plantas m-2 e sete proporções de nabiça: triticale (0:300, 50:250, 100:200, 150:150, 200:100, 250:50 e 300:0), sendo conduzidos em delineamento experimental de blocos casualizados, com cinco repetições. Os resultados foram analisados pelo método convencional de análise de experimentos substitutivos e pelo método da produção recíproca total e por planta. Os índices calculados, a partir da massa seca das plantas, indicaram o triticale como competidor superior à nabiça.

Evaluation of the analgesic and antiedematogenic activities of Quassia amara bark extract

We evaluated the possible antiedematogenic, antinociceptive and/or sedative effects of four different extracts obtained from the bark of Quassia amara namely, 70% ethanol (70EtOH), 100% ethanol (100EtOH), dichloromethane (DCM) and hexane extracts (HEX). The oral administration (100, 250 and 500 mg/kg) of these extracts did not show significant effects in any experiment. However, when administered intraperitoneally, the HEX extract decreased the paw edema induced by carrageenan, showed antinociceptive effects on the hot-plate test and on acetic acid-induced writhing, and showed sedative effects on pentobarbital-induced sleep. Naloxone did not reverse the antinociceptive effect of this extract. In conclusion, although the mechanisms are uncertain, the results demonstrated that these effects are apparently related to sedative and muscle relaxant or psychomimetic activities of the HEX extract of the plant. (C) 2002 Elsevier B.V. Ireland Ltd. All rights reserved.

Brine shrimp (Artemia salina Leach) bioassay of extracts from Lychnophoriopsis candelabrum and different Lychnophora species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of malathion and cadmium on acetylcholinesterase activity and metallothionein levels in the fish Seriola dumerilli

The potential use of acetylcholinesterase (AChE) and metallothionein (MT) responses as biomarker of organophosphorous (OPs) and trace metal were assessed in fish Seriola dumerilli exposed to 0, 4, 6 mg/kg of malathion for 2, 7 and 13 days, and to 0, 50, 100, 250 mu g/kg of Cd for 2 days. Brain AChE was significantly inhibited after 2 and 7 days of malathion exposure, in a dose-response manner, but no inhibition was observed after 13 days of exposure. When exposed to Cd for 2 days, S. dumerelli presented an increase in AChE activity at a concentration of 50 mu g/kg, but a strong and dose-dependent AChE inhibition at 100 and 250 mu g/kg. Cd treatment also caused a rapid increase in MTs concentration in liver, even at the lower concentration. Our experiments indicate that the measurement of hepatic MT concentration and brain AChE activity in S. dumerilli would be useful biomarkers of OP and Cd exposure and/or effects.

Effects of turmeric and its active principle, curcumin, on bleomycin-induced chromosome aberrations in Chinese hamster ovary cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)