New Methods for Triangulation-based Shape Acquisition using Laser Scanners

Tradicionalment, la reproducció del mon real se'ns ha mostrat a traves d'imatges planes. Aquestes imatges se solien materialitzar mitjançant pintures sobre tela o be amb dibuixos. Avui, per sort, encara podem veure pintures fetes a ma, tot i que la majoria d'imatges s'adquireixen mitjançant càmeres, i es mostren directament a una audiència, com en el cinema, la televisió o exposicions de fotografies, o be son processades per un sistema computeritzat per tal d'obtenir un resultat en particular. Aquests processaments s'apliquen en camps com en el control de qualitat industrial o be en la recerca mes puntera en intel·ligència artificial. Aplicant algorismes de processament de nivell mitja es poden obtenir imatges 3D a partir d'imatges 2D, utilitzant tècniques ben conegudes anomenades Shape From X, on X es el mètode per obtenir la tercera dimensió, i varia en funció de la tècnica que s'utilitza a tal nalitat. Tot i que l'evolució cap a la càmera 3D va començar en els 90, cal que les tècniques per obtenir les formes tridimensionals siguin mes i mes acurades. Les aplicacions dels escàners 3D han augmentat considerablement en els darrers anys, especialment en camps com el lleure, diagnosi/cirurgia assistida, robòtica, etc. Una de les tècniques mes utilitzades per obtenir informació 3D d'una escena, es la triangulació, i mes concretament, la utilització d'escàners laser tridimensionals. Des de la seva aparició formal en publicacions científiques al 1971 [SS71], hi ha hagut contribucions per solucionar problemes inherents com ara la disminució d'oclusions, millora de la precisió, velocitat d'adquisició, descripció de la forma, etc. Tots i cadascun dels mètodes per obtenir punts 3D d'una escena te associat un procés de calibració, i aquest procés juga un paper decisiu en el rendiment d'un dispositiu d'adquisició tridimensional. La nalitat d'aquesta tesi es la d'abordar el problema de l'adquisició de forma 3D, des d'un punt de vista total, reportant un estat de l'art sobre escàners laser basats en triangulació, provant el funcionament i rendiment de diferents sistemes, i fent aportacions per millorar la precisió en la detecció del feix laser, especialment en condicions adverses, i solucionant el problema de la calibració a partir de mètodes geomètrics projectius.

A influência das atitudes e da ansiedade face à morte na imortalidade simbólica em estudantes

O presente estudo propõe-se verificar a influência das Atitudes e da Ansiedade Face à Morte na Imortalidade Simbólica em estudantes universitários. Procura igualmente perceber quais as relações entre as diferentes variáveis. Com este propósito, foram aplicadas as versões portuguesas do Death Attitude Profile Revised (DAP-R; Wong, Reker, & Gesser, 1994), da Death Anxiety Scale (DAS; Templer, 1970) e da The Sense of Symbolic Immortality Scale (SSIS; Drolet, 1990), juntamente com um Questionário de dados sociodemográficos. Participaram no estudo 310 estudantes universitários de 1º e 2º ciclo, com idades compreendidas entre os 18 e os 56 anos. Os resultados mostram que os estudantes obtêm valores superiores de aceitação neutra e inferiores de aceitação de escape. Relativamente à idade os indivíduos mais velhos apresentam valores superiores de medo e de evitamento da morte, assim como valores inferiores de desejo de imortalidade simbólica. Os homens apresentam resultados mais elevados de aceitação neutra, de escape, de ansiedade face à morte e de desejo de imortalidade simbólica. Constata-se que as atitudes negativas perante a morte e a imortalidade simbólica se correlacionam negativamente com a ansiedade. Os resultados encontrados corroboram a tese de que existe influência das atitudes e da ansiedade no desejo de imortalidade simbólica.

A percepção do clima motivacional em Educação Física em alunos do 3º ciclo e Ensino Secundário : influência do estilo de vida, da atitude face à Educação Física e da orientação de objectivos

Este trabalho teve como objetivo principal analisar os estilos de vida de alunos de Educação Física, e relaciona-los com a perceção de competência, orientação de objetivos para a mestria, performance aproach, performance avoidance, perceção de clima motivacional para a mestria, performance aproach, performance avoidance, atitude gosto e importância face a disciplina de Educação Física. Neste sentido foi aplicado um Questionário (Papaioannou et al. 2007, versão adaptada por Martins, 2010), em quatro escolas da rede de estágio pedagógico em Educação Física de 3º ciclo e Secundário, de modo a avaliar as perceções de 199 alunos com idades compreendidas entre os 14-20 anos. Os resultados revelaram diferenças significativas entre alunos ativos e sedentários ao nível da perceção de competência (p=0,000), orientação de objetivos para a mestria (p=0,000), orientação de objetivos performance avoidance (p=0,028), perceção de clima motivacional para a mestria (p=0,010), atitude gosto pela educação física e suas matérias (p=0,001), e a atitude e importância atribuída à EF (p=0,002). A análise das correlações demonstrou a existência de relação entre o estilo de vida sedentário relativamente à perceção de competência (p=0,004), e orientação de objetivos performance avoidance esta ultima no sentido inverso (p=0,010). Em relação aos alunos ativos apenas se verificou a existência de correlação para a orientação de objetivos performance aproach (p=0,048).

Ateliê caderneta de cromos : estudo sobre a relação de uma prática artística visual não formal e inclusão

Esta investigação teve como objeto de estudo o Ateliê Caderneta de Cromos, do projeto Geração Cool, fruto de uma parceria entre várias instituições do concelho de Almada. Trata--se de um projeto de desenvolvimento social comunitário, multicultural, associado a uma escola. Através de um estudo de caso, pretendeu analisar-se, criticamente, um modelo não formal de práticas ligadas às artes visuais, vocacionado para jovens em risco e mostrar como as aprendizagens desenvolvidas num ateliê de artes visuais contribuem para o processo de inclusão desses jovens. Desenvolveu-se um quadro teórico abrangente, no sentido de sustentar as perguntas iniciais, referenciando questões consideradas pertinentes tais como: visões contemporâneas das realidades multiculturais das periferias urbanas; perspetivas pós-modernistas de ensino artístico, defensoras de uma construção cognitiva; ação dos projetos artísticos de desenvolvimento social e ainda, a importância ética e social dos currículos artísticos atuais. Tendo como referência a hipótese de antagonismo e/ou complementaridade entre o ato pedagógico não formal e o institucional, o estudo procurou estabelecer uma relação entre essa prática e a inclusão, ao identificar e desmontar um roteiro estratégico de aprendizagens. O ato pedagógico no Ateliê mostrou potenciar uma aprendizagem construtiva nas respostas produzidas, sendo também significativa pelo caráter experiencial vivido e cognitiva no sentido em que determina a construção de um significado, assumido como a própria assunção identitária.

La radio se hizo joven una mirada a los jóvenes, la radio y la ciudad

Esta investigación se mueve en tres áreas temáticas: los jóvenes, la radio y la ciudad. Busca, además de explorar las interrelaciones que se dan entre estos tres componentes, comprender cómo se concibe —desde la producción— a los jóvenes (qué idea se tiene de ellos) a la hora de diseñar un programa radial juvenil. Indaga desde qué parámetros —con respecto a la juventud— se han diseñado dos programas juveniles de una emisora universitaria, y sondea cómo los productores radiales asumen la interacción de sus espacios con los jóvenes y con la ciudad. Esta investigación parte desde la producción y no desde el consumo radial, y el marco referencial sobre el que se mueve, es la reflexión sobre la ciudad. Puede decirse que disciplinariamente esta investigación —cualitativa— está inserta en el campo de los estudios de la comunicación y los estudios urbanos; por ello, el sustento teórico en el que se basa se refiere a autores — fundamentalmente latinoamericanos— que trabajan estas perspectivas. El trabajo puede dividirse en dos partes. La primera, es una aproximación teórica y conceptual a las áreas temáticas. La segunda, se refiere a las interrelaciones que pueden darse entre los jóvenes, la radio y la ciudad, y se hace referencia a dos programas juveniles de Radio Universidad del Cauca, en Popayán, Colombia. Más que un análisis o estudio de caso, es una contextualización de la teoría en unas experiencias radiofónicas concretas. El tono de escritura de este trabajo apela a tres “estéticas”, que no son sucesivas sino más bien transversales en toda la tesis. Por un lado está la escritura más académica o teórica, por llamarla de alguna manera. Por otra parte hay un acercamiento a lo vivencial o experiencial que suscitan los temas. Finalmente hay una suerte de aproximación periodística al objeto de estudio.

Artificial Cavities and Nest Site Selection by Puerto Rican Parrots: a Multiscale Assessment

We examined nest site selection by Puerto Rican Parrots, a secondary cavity nester, at several spatial scales using the nest entrance as the central focal point relative to 20 habitat and spatial variables. The Puerto Rican Parrot is unique in that, since 2001, all known nesting in the wild has occurred in artificial cavities, which also provided us with an opportunity to evaluate nest site selection without confounding effects of the actual nest cavity characteristics. Because of the data limitations imposed by the small population size of this critically endangered endemic species, we employed a distribution-free statistical simulation approach to assess site selection relative to characteristics of used and unused nesting sites. Nest sites selected by Puerto Rican Parrots were characterized by greater horizontal and vertical visibility from the nest entrance, greater density of mature sierra palms, and a more westerly and leeward orientation of nest entrances than unused sites. Our results suggest that nest site selection in this species is an adaptive response to predation pressure, to which the parrots respond by selecting nest sites offering advantages in predator detection and avoidance at all stages of the nesting cycle. We conclude that identifying and replicating the “nest gestalt” of successful nesting sites may facilitate conservation efforts for this and other endangered avian species.

The influence of mineral solubility and soil solution concentration on the toxicity of copper to Eisenia fetida Savigny

The OECD 14 d earthworm acute toxicity test was used to determine the toxicity of copper added as copper nitrate (Cu(NO3)(2)), copper sulphate (CuSO4) and malachite (Cu-2(OH)(2)(CO3)) to Eisenia fetida Savigny. Cu(NO3)(2), and CuSO4 were applied in both an aqueous (aq) and solid (s) form, Cu-2(OH)(2)(CO3) was added as a solid. Soil solution was extracted by centrifugation, and analysed for copper. Two extractants [0.01 M CaCl2 and 0.005 M diethylenetriminpentaacetic acid (DTPA)] were used as a proxy of the bioavailable copper fraction in the soil. For bulk soil copper content the calculated copper toxicity decreased in the order nitrate > sulphide > carbonate, the same order as decreasing solubility of the metal compounds. For Cu(NO3)(2) and CuSO4, the LC50s obtained were not significantly different when the compound was added in solution or solid form. There was a significant correlation between the soil solution copper concentration and the percentage earthworm mortality for all 3 copper compounds (P less than or equal to 0.05) indicating that the soil pore water copper concentration is important for determining copper availability and toxicity to E. fetida. In soil avoidance tests the earthworms avoided the soils treated with Cu(NO3)(2) (aq and s) and CuSO4 (aq and s), at all concentrations used (110-8750 mug Cu g(-1), and 600-8750 mug Cu g(-1) respectively). In soils treated with Cu-2(OH2)CO3, avoidance behaviour was exhibited at all concentrations greater than or equal to3500 mug Cu g(-1). There was no significant correlation between the copper extracted by either CaCl2 or DTPA and percentage mortality. These two extractants are therefore not useful indicators of copper availability and toxicity to E. fetida.

The soil-dwelling earthworm Allolobophora chlorotica modifies its burrowing behaviour in response to carbendazim applications

Carbendazim-amended soil was placed above or below unamended soil. Control tests comprised two layers of unamended soil. Allolobophora chlorotica earthworms were added to either the upper or the unamended soil. After 72 h vertical distributions of earthworms were compared between control and carbendazim-amended experiments. Earthworm distributions in the carbendazim-amended test containers differed significantly from the ‘normal’ distribution observed in the control tests. In the majority of the experiments, earthworms significantly altered their burrowing behaviour to avoid carbendazim. However, when earthworms were added to an upper layer of carbendazim-amended soil they remained in this layer. This non-avoidance is attributed to (1) the earthworms’ inability to sense the lower layer of unamended soil and (2) the toxic effect of carbendazim inhibiting burrowing. Earthworms modified their burrowing behaviour in response to carbendazim in the soil. This may explain anomalous results observed in pesticide field trials when carbendazim is used as a control substance.

Determining the influence of rainfall patterns and carbendazim on the surface activity of the earthworm Lumbricus terrestris

Carbendazim is highly toxic to earthworms and is used as a standard control substance when running field-based trials of pesticides, but results using carbendazim are highly variable. In the present study, impacts of timing of rainfall events following carbendazim application on earthworms were investigated. Lumbricus terrestris were maintained in soil columns to which carbendazim and then deionized water (a rainfall substitute) were applied. Carbendazim was applied at 4 kg/ha, the rate recommended in pesticide field trials. Three rainfall regimes were investigated: initial and delayed heavy rainfall 24 h and 6 d after carbendazim application, and frequent rainfall every 48 h. Earthworm mortality and movement of carbendazim through the soil was assessed 14 d after carbendazim application. No detectable movement of carbendazim occurred through the soil in any of the treatments or controls. Mortality in the initial heavy and frequent rainfall was significantly higher (approximately 55%) than in the delayed rainfall treatment (approximately 25%). This was due to reduced bioavailability of carbendazim in the latter treatment due to a prolonged period of sorption of carbendazim to soil particles before rainfall events. The impact of carbendazim application on earthworm surface activity was assessed using video cameras. Carbendazim applications significantly reduced surface activity due to avoidance behavior of the earthworms. Surface activity reductions were least in the delayed rainfall treatment due to the reduced bioavailability of the carbendazim. The nature of rainfall events' impacts on the response of earthworms to carbendazim applications, and details of rainfall events preceding and following applications during field trials should be made at a higher level of resolution than is currently practiced according to standard International Organization for Standardization protocols.

The use of agricultural, open and forest habitats by juvenile Mauritius Kestrels Falco punctatus

Knowledge of tropical raptor habitat use is limited and yet a thorough understanding is vital when trying to conserve endangered species. We used a well studied, reintroduced population of the vulnerable Mauritius Kestrel Falco punctatus to investigate habitat preferences in a modified landscape. We constructed a high resolution digital habitat map and radiotracked 13 juvenile Kestrels to quantify habitat preferences. We distinguished seven habitat types in our study area and tracked Kestrels from 71 to 130 days old during which they dispersed from their natal territory and settled within a home-range after reaching independence. Mean home-range size was 0.95 km(2) characterized by a bimodal pattern of intensity around the natal site and post-independence home-range. Compositional analysis showed that home-ranges were located non-randomly with respect to habitat but there was no evidence to suggest differential use of habitats within home-ranges. Native and semi-invaded forest and grassland were consistently preferred, whereas agriculture was used significantly less than other habitats. No difference was found between the available length of edge dividing native forest and grassland within a home-range when compared to that available within a 2.35-km buffer around their nest-site, based on the maximum distance a juvenile was found to disperse. Repeating the analysis in three dimensions gave very similar results. Our results suggest that Mauritius Kestrels are not obligate forest dwellers as was once thought but can also exploit open habitats such as grassland. Kestrels may be using isolated mature trees within grassland as vantage points for hunting in the same way as they use the natural stratified forest structure. We suggest that the avoidance of agriculture is partly due to a lack of such vantage points. The conservation importance of forest degradation and agricultural encroachment is highlighted and comparisons with the habitat preferences of other tropical falcons are discussed.

Phenotyping parents of mapping populations of rice for heat tolerance during anthesis

Seed set of rice (Oryza sativa L.) is highly sensitive to short episodes of high temperature at anthesis events that are likely to be more frequent in future climates. Breeding for tolerance is therefore an essential component of adaptation to climate variability and change. Experiments were conducted in 2003 and 2004 at optimum (30 degrees C daytime) and high (35 and 38 degrees C) air temperature using parents of some prominent mapping populations (i) to determine whether there were differences in the daily flowering pattern and hence a potential heat avoidance mechanism, and (ii) to identify rice genotypes having true heat tolerance during anthesis, that is, high seed set in spikelets exposed to high temperature. Rice cultivar CG14 (O. glaberrima) reached peak anthesis earlier in the morning (1.5 h after dawn) under both control (30 degrees C) and high (38 degrees C) temperature conditions than O. sativa genotypes (>= 3 h after dawn). Exposure to high temperature (centered on the time of peak anthesis) for 6 h reduced spikelet fertility more than exposure for 2 h, and fertility was lower at 38 degrees C than at 35 degrees C. Genotypic ranking for spikelet fertility at 35 and 38 degrees C was highly correlated in both 2003 and 2004. Fertility was also highly correlated across years, suggesting a consistent and reproducible response of spikelet fertility to temperature. The check cultivar N22 was the most heat tolerant genotype (64-86% fertility at 38 degrees C) and cultivars Azucena and Moroberekan the most susceptible (<8%).

Feeding responses of carabid beetles to dimethoate-contaminated prey

1 The feeding responses of Pterostichus madidus Fab., P. melanarius Illiger and Nebria brevicollis Fab. (Coleoptera: Carabidae) to dimethoate-contaminated prey were investigated in 'no-choice' and 'choice' feeding tests. 2 In the no-choice tests, starved beetles were presented with aphid prey treated with four concentrations of dimethoate. In the choice tests, treated and untreated prey were presented together and the feeding preferences of the starved beetles observed. 3 No avoidance or rejection behaviour was seen in any of the carabids in either of the tests, i.e. no discrimination of the treated and untreated prey was observed. 4 Sufficient dimethoate was consumed with the aphid prey to cause significant mortality levels in the carabids. 5 The concentrations of dimethoate used in these experiments are comparable to field exposure, so carabids feeding in treated fields and field margins could potentially suffer lethal effects via the indirect exposure route of consuming contaminated prey.

A critical assessment of a desk study comparing crop production systems: The example of the 'system of rice intensification' versus 'best management practice'

When assessing hypotheses, the possibility and consequences of false-positive conclusions should be considered along with the avoidance of false-negative ones. A recent assessment of the system of rice intensification (SRI) by McDonald et al. [McDonald, A.J., Hobbs, P.R., Riha, S.J., 2006. Does the system of rice intensification outperform conventional best management? A synopsis of the empirical record. Field Crops Res. 96, 31-36] provides a good example where this was not done as it was preoccupied with avoiding false-positives only. It concluded, based on a desk study using secondary data assembled selectively from diverse sources and with a 95% level of confidence, that 'best management practices' (BMPs) on average produce 11% higher rice yields than SRI methods, and that, therefore, SRI has little to offer beyond what is already known by scientists.

Carbon-decorated FePt nanoparticles

FePt magnetic nanoparticles are an important candidate material for many future magnetic applications. FePt exists as two main phases, that is, a disordered face-centered cubic (fcc) structure, which is generally prepared by chemical methods at low temperatures, and the high-temperature chemically ordered face-centered tetragonal (fct) structure. The fee FePt, with low coercivity but associated with superparamagnetic properties, may find applications as a magnetic fluid or as a nanoscale carrier for chemical or biochemical species in biomedical areas, while fct FePt is proposed for use in ultrahigh-density magnetic recording applications. However, for both of these applications an enhancement of the intrinsically weak magnetic properties, the avoidance of magnetic interferences from neighbor particles, and the improved stability of the small magnetic body remain key practical issues. We report a simple synthetic method for producing FePt nanoparticles that involves hydrothermal treatment of Fe and Pt precursors in glucose followed by calcination at 900 degrees C. This new method produces thermally stable spheroidal graphite nanoparticles (large and fullerene-like) that encapsulate or decorate FePt particles of ca. 5 nm with no severe macroscopic particle coalescence. Also, a low coercivity of the material is recorded; indicative of small magnetic interference from neighboring carbon-coated particles. Thus, this simple synthetic method involves the use of a more environmentally acceptable glucose/aqueous phase to offer a protective coating for FePt nanoparticles. It is also believed that such a synthetic protocol can be readily extended to the preparation of other graphite-coated magnetic iron alloys of controlled size, stoichiometry, and physical properties.

Monodisperse binary nanocomposite in silica with enhanced magnetization for magnetic separation

The majority of research on magnetic nanoparticles has focused on optical, electrical, and magnetic storage areas. Recently, the application of magnetic nanoparticles as magnetically separable nanovehicles for chemical or biological species has become an area of intensive research but with rather different challenging criteria that are yet to be addressed. For example, the enhancement of intrinsically weak magnetic properties, avoidance of magnetic interactions among particles, and improvement of the stability of the nanoparticles remain key issues. Here, it is demonstrated using sequential nanochemistry preparation techniques that exchange-coupled nanomagnets, such as FePt-Fe3Pt or FePt-Fe3O4 with dramatically enhanced magnetization, can be placed inside a silica nanosphere. The advantages of enhanced magnetization and the provision of protective coating and anchored sites on the silica shell surface render these new coated particles suitable for use in magnetic separation.