Temporal Surface Reconstruction

This thesis investigates the problem of estimating the three-dimensional structure of a scene from a sequence of images. Structure information is recovered from images continuously using shading, motion or other visual mechanisms. A Kalman filter represents structure in a dense depth map. With each new image, the filter first updates the current depth map by a minimum variance estimate that best fits the new image data and the previous estimate. Then the structure estimate is predicted for the next time step by a transformation that accounts for relative camera motion. Experimental evaluation shows the significant improvement in quality and computation time that can be achieved using this technique.

Estudo da periodicidade temporal de chuvas em uma bacia hidrográfica dos rios Turvo / Grande: uma proposta.

O presente trabalho desenvolve os seguintes temas: Estudo da distribuição temporal das chuvas, determinando a frequencia com que ocorrem veranicos e chuvas maiores que um limite especificado e suas durações médias; Avaliação do ciclo de ocorrência das chuvas dentro do ano, ou seja, o ciclo segue alguma tendência ou ocorre ao acaso; Avaliação de possíveis associações entre a distribuição temporal e espacial das chuvas e os fenômenos La niña, El niño e Dipolo do Atlântico. Assim, o presente trabalho objetiva a determinação da periodicidade da ocorrência de chuvas e veranicos em uma pequena área, sobre a influência de fenômenos climáticos ou não.

Desenvolvimento de ferramenta computacional para estudo de variabilidade espacial e temporal por meio de geoestatística: uma proposta.

Este trabalho visa o desenvolvimento de um sistema computacional que implemente os conceitos geoestatísticos para estudo de viabilidade temporal e espacial, de maneira amigável, rápida e consistente, em ambiente Windows e integrado à Web.

Monitoramento espaço-temporal da cana-de-açúcar a partir de índices espectrais de vegetação.

Para culturas agrícolas que abrangem grandes áreas, como é o caso da cana-de-açúcar no Brasil, técnicas de geoprocessamento aplicadas a imagens orbitais de alta resolução temporal apresentam grande potencial de mapear e monitorar os ciclos fenológicos/agronômicos das lavouras. Para essa finalidade, destaca-se o uso de séries temporais de índices espectrais de vegetação (IV) como NDVI (Normalized Difference Vegetation Index) e EVI (Enhanced Vegetation Index) calculados a partir das imagens orbitais de reflectância. Este documento apresenta resultados de uma pesquisa que avaliou a utilização de um método de suavização de perfis temporais de IV e a posterior derivação de parâmetros do ciclo fenológico/agrícola de talhões de cana-de-açúcar, com o objetivo de monitorar e mapear áreas ocupadas por cana-de-açúcar e de distinguir áreas de cana-planta e cana-soca. Foram utilizadas séries temporais de NDVI e EVI do sensor MODIS (Moderate Resolution Imaging Spectroradiometer) a bordo do satélite Terra referentes a uma região do Nordeste do Estado de São Paulo, densamente ocupada por cana-de-açúcar. Os resultados obtidos mostraram grande utilidade das séries temporais de IV do MODIS para monitorar o ciclo agronômico/fenológico de talhões de cana-de-açúcar. Foi possível acompanhar o desenvolvimento da cana-de-açúcar e identificar a ocorrência de cana-planta ou cana-soca para um determinado talhão. O cultivo de uma cultura de ciclo mais curto, ao fazer a reforma do talhão de cana-de-açúcar, também foi identificado nos perfis temporais. A metodologia desenvolvida para classificação de áreas de cana-de-açúcar obteve erro de comissão relativamente pequeno (<10%), mas ao custo de erro de emissão mais elevado (>40%). A classificação realizada para distinção entre áreas de cana-planta e cana-soca também apresentou resultados interessantes, com erro de emissão em torno de 4% e erro de comissão >30%.

Monitoramento espaço-temporal da cana-de-açúcar a partir de índices espectrais de vegetação.

Para culturas agrícolas que abrangem grandes áreas, como é o caso da cana-de-açúcar no Brasil, técnicas de geoprocessamento aplicadas a imagens orbitais de alta resolução temporal apresentam grande potencial de mapear e monitorar os ciclos fenológicos/agronômicos das lavouras. Para essa finalidade, destaca-se o uso de séries temporais de índices espectrais de vegetação (IV) como NDVI (Normalized Difference Vegetation Index) e EVI (Enhanced Vegetation Index) calculados a partir das imagens orbitais de reflectância. Este documento apresenta resultados de uma pesquisa que avaliou a utilização de um método de suavização de perfis temporais de IV e a posterior derivação de parâmetros do ciclo fenológico/agrícola de talhões de cana-de-açúcar, com o objetivo de monitorar e mapear áreas ocupadas por cana-de-açúcar e de distinguir áreas de cana-planta e cana-soca. Foram utilizadas séries temporais de NDVI e EVI do sensor MODIS (Moderate Resolution Imaging Spectroradiometer) a bordo do satélite Terra referentes a uma região do Nordeste do Estado de São Paulo, densamente ocupada por cana-de-açúcar. Os resultados obtidos mostraram grande utilidade das séries temporais de IV do MODIS para monitorar o ciclo agronômico/fenológico de talhões de cana-de-açúcar. Foi possível acompanhar o desenvolvimento da cana-de-açúcar e identificar a ocorrência de cana-planta ou cana-soca para um determinado talhão. O cultivo de uma cultura de ciclo mais curto, ao fazer a reforma do talhão de cana-de-açúcar, também foi identificado nos perfis temporais. A metodologia desenvolvida para classificação de áreas de cana-de-açúcar obteve erro de comissão relativamente pequeno (<10%), mas ao custo de erro de omissão mais elevado (>40%). A classificação realizada para distinção entre áreas de cana-planta e cana-soca também apresentou resultados interessantes, com erro de omissão em torno de 4% e erro de comissão >30%.

Variação temporal e espacial de parâmetros de qualidade de água no reservatório de Barra Bonita/SP, como subsídio ao manejo da bacia de contribuição.

2013

C-Kit(+) Cells Isolated from Developing Kidneys Are a Novel Population of Stem Cells with Regenerative Potential

The presence of tissue specific precursor cells is an emerging concept in organ formation and tissue homeostasis. Several progenitors are described in the kidneys. However, their identity as a true stem cell remains elusive. Here, we identify a neonatal kidney-derived c-kit(+) cell population that fulfills all of the criteria as a stem cell. These cells were found in the thick ascending limb of Henle's loop and exhibited clonogenicity, self-renewal, and multipotentiality with differentiation capacity into mesoderm and ectoderm progeny. Additionally, c-kit(+) cells formed spheres in nonadherent conditions when plated at clonal density and expressed markers of stem cells, progenitors, and differentiated cells. Ex vivo expanded c-kit(+) cells integrated into several compartments of the kidney, including tubules, vessels, and glomeruli, and contributed to functional and morphological improvement of the kidney following acute ischemia-reperfusion injury in rats. Together, these findings document a novel neonatal rat kidney c-kit(+) stem cell population that can be isolated, expanded, cloned, differentiated, and used for kidney repair following acute kidney injury. These cells have important biological and therapeutic implications. STEM Cells 2013;31:1644-1656

Comportamento temporal de genótipos de girassol no Cerrado do Distrito Federal em safrinha de 2014 e 2015.

RESUMO:Com o objetivo de avaliar o comportamento agronômico de genótipos de girassol no Cerrado do Distrito Federal, foram conduzidos ensaios na safrinha dos anos de 2014 e 2015, na estação experimental da Embrapa Cerrados, Planaltina, DF. O delineamento experimental foi de blocos ao acaso com quatro repetições, e foram avaliados 12 genótipos de girassol: HLA 2015, NTC 90, SYN 065, M734, BRS G44, HLA 2014, BRS G45, BRS G43, HLA 2013, HLA 2017, BRS G46, HLA 2016. As características avaliadas foram rendimento de grãos, tamanho do capitulo, peso de mil aquênios, altura de plantas e dias de floração inicial. Diferenças significativas foram encontradas para as características avaliadas. Os genótipos que se destacaram em relação ao rendimento de grãos foram HLA 2014 (3.161 kg ha-1) e a testemunha M743 (3.212 kg ha-1). Além disso, o ensaio do ano 2014 apresentou uma média de rendimento maior (2.829 kg ha-1) e mais precoces (63,10 dias) em relação a 2015. O trabalho permitiu a identificação de materiais promissores para exploração em programas de melhoramento genético. ABSTRACT: Aiming the evaluation on agronomic behavior of sunflower genotypes in the Brazilian savannah, experiments were carried on in the second crop of 2014 and 2015 at Centro de Pesquisa Agropecuária dos Cerrados (Embrapa), Planaltina, DF. A complete randomized block design was used with four replications and 12 genotypes of sunflower were analyzed: HLA 2015, NTC 90, SYN 065, M734, BRS G44, HLA 2014, BRS G45, BRS G43, HLA 2013, HLA 2017, BRS G46, HLA 2016.The evaluated characteristics were grain yield, head, weight thousand achenes, plant height, and flowering time. Significant differences were found in all evaluated characteristics. The genotypes that stood out in seed yield were HLA 2014 (3161 kg ha-1) and M743 (3212 kg ha-1). Besides, the 2014 experiment presented a seed yield average higher (2829 kg ha-1), and earlier flowering (63,10 days) when compared to 2015 experiment. This study allowed the identification of promising materials to explore in breeding programs.

¿Es aspectual o temporal el carácter de la oposición imperfectivo /perfectivo?

In this article, we present a short historical summary of the following terms: the aspect and the imperfective /perfective opposition to answer the question if the imperfective /perfective opposition has an aspectual or temporal character. We distinguish two types of the aforementioned opposition: the temporal imperfective /perfective opposition expressed by the Spanish tenses Pretérito Indefinido / Pretérito Imperfecto that is characterized by the property of [± temporal delimitation]; and the aspectual imperfective /perfective opposition recognizable in the aspectual system of the Slavonic languages that is characterized by the property of [± conclusion of the process].

Temporal Locality in Web Request Streams: Sources, Characteristics, and Caching Implications

Temporal locality of reference in Web request streams emerges from two distinct phenomena: the popularity of Web objects and the {\em temporal correlation} of requests. Capturing these two elements of temporal locality is important because it enables cache replacement policies to adjust how they capitalize on temporal locality based on the relative prevalence of these phenomena. In this paper, we show that temporal locality metrics proposed in the literature are unable to delineate between these two sources of temporal locality. In particular, we show that the commonly-used distribution of reference interarrival times is predominantly determined by the power law governing the popularity of documents in a request stream. To capture (and more importantly quantify) both sources of temporal locality in a request stream, we propose a new and robust metric that enables accurate delineation between locality due to popularity and that due to temporal correlation. Using this metric, we characterize the locality of reference in a number of representative proxy cache traces. Our findings show that there are measurable differences between the degrees (and sources) of temporal locality across these traces, and that these differences are effectively captured using our proposed metric. We illustrate the significance of our findings by summarizing the performance of a novel Web cache replacement policy---called GreedyDual*---which exploits both long-term popularity and short-term temporal correlation in an adaptive fashion. Our trace-driven simulation experiments (which are detailed in an accompanying Technical Report) show the superior performance of GreedyDual* when compared to other Web cache replacement policies.

GreedyDual* Web Caching Algorithm: Exploiting the Two Sources of Temporal Locality in Web Request Streams

The relative importance of long-term popularity and short-term temporal correlation of references for Web cache replacement policies has not been studied thoroughly. This is partially due to the lack of accurate characterization of temporal locality that enables the identification of the relative strengths of these two sources of temporal locality in a reference stream. In [21], we have proposed such a metric and have shown that Web reference streams differ significantly in the prevalence of these two sources of temporal locality. These finding underscore the importance of a Web caching strategy that can adapt in a dynamic fashion to the prevalence of these two sources of temporal locality. In this paper, we propose a novel cache replacement algorithm, GreedyDual*, which is a generalization of GreedyDual-Size. GreedyDual* uses the metrics proposed in [21] to adjust the relative worth of long-term popularity versus short-term temporal correlation of references. Our trace-driven simulation experiments show the superior performance of GreedyDual* when compared to other Web cache replacement policies proposed in the literature.

Real-Time Spatio-Temporal Query Processing in Mobile Ad-Hoc Sensor Networks

Personal communication devices are increasingly equipped with sensors that are able to collect and locally store information from their environs. The mobility of users carrying such devices, and hence the mobility of sensor readings in space and time, opens new horizons for interesting applications. In particular, we envision a system in which the collective sensing, storage and communication resources, and mobility of these devices could be leveraged to query the state of (possibly remote) neighborhoods. Such queries would have spatio-temporal constraints which must be met for the query answers to be useful. Using a simplified mobility model, we analytically quantify the benefits from cooperation (in terms of the system's ability to satisfy spatio-temporal constraints), which we show to go beyond simple space-time tradeoffs. In managing the limited storage resources of such cooperative systems, the goal should be to minimize the number of unsatisfiable spatio-temporal constraints. We show that Data Centric Storage (DCS), or "directed placement", is a viable approach for achieving this goal, but only when the underlying network is well connected. Alternatively, we propose, "amorphous placement", in which sensory samples are cached locally, and shuffling of cached samples is used to diffuse the sensory data throughout the whole network. We evaluate conditions under which directed versus amorphous placement strategies would be more efficient. These results lead us to propose a hybrid placement strategy, in which the spatio-temporal constraints associated with a sensory data type determine the most appropriate placement strategy for that data type. We perform an extensive simulation study to evaluate the performance of directed, amorphous, and hybrid placement protocols when applied to queries that are subject to timing constraints. Our results show that, directed placement is better for queries with moderately tight deadlines, whereas amorphous placement is better for queries with looser deadlines, and that under most operational conditions, the hybrid technique gives the best compromise.

Constraint-based Mining of Frequent Arrangements of Temporal Intervals

The problem of discovering frequent arrangements of temporal intervals is studied. It is assumed that the database consists of sequences of events, where an event occurs during a time-interval. The goal is to mine temporal arrangements of event intervals that appear frequently in the database. The motivation of this work is the observation that in practice most events are not instantaneous but occur over a period of time and different events may occur concurrently. Thus, there are many practical applications that require mining such temporal correlations between intervals including the linguistic analysis of annotated data from American Sign Language as well as network and biological data. Two efficient methods to find frequent arrangements of temporal intervals are described; the first one is tree-based and uses depth first search to mine the set of frequent arrangements, whereas the second one is prefix-based. The above methods apply efficient pruning techniques that include a set of constraints consisting of regular expressions and gap constraints that add user-controlled focus into the mining process. Moreover, based on the extracted patterns a standard method for mining association rules is employed that applies different interestingness measures to evaluate the significance of the discovered patterns and rules. The performance of the proposed algorithms is evaluated and compared with other approaches on real (American Sign Language annotations and network data) and large synthetic datasets.

Temporal Dynamics of Decision-Making during Motion Perception in the Visual Cortex

How does the brain make decisions? Speed and accuracy of perceptual decisions covary with certainty in the input, and correlate with the rate of evidence accumulation in parietal and frontal cortical "decision neurons." A biophysically realistic model of interactions within and between Retina/LGN and cortical areas V1, MT, MST, and LIP, gated by basal ganglia, simulates dynamic properties of decision-making in response to ambiguous visual motion stimuli used by Newsome, Shadlen, and colleagues in their neurophysiological experiments. The model clarifies how brain circuits that solve the aperture problem interact with a recurrent competitive network with self-normalizing choice properties to carry out probablistic decisions in real time. Some scientists claim that perception and decision-making can be described using Bayesian inference or related general statistical ideas, that estimate the optimal interpretation of the stimulus given priors and likelihoods. However, such concepts do not propose the neocortical mechanisms that enable perception, and make decisions. The present model explains behavioral and neurophysiological decision-making data without an appeal to Bayesian concepts and, unlike other existing models of these data, generates perceptual representations and choice dynamics in response to the experimental visual stimuli. Quantitative model simulations include the time course of LIP neuronal dynamics, as well as behavioral accuracy and reaction time properties, during both correct and error trials at different levels of input ambiguity in both fixed duration and reaction time tasks. Model MT/MST interactions compute the global direction of random dot motion stimuli, while model LIP computes the stochastic perceptual decision that leads to a saccadic eye movement.

Learning Temporal Contexts and Priming-Preparation Modes for Pattern Recognition

The system presented here is based on neurophysiological and electrophysiological data. It computes three types of increasingly integrated temporal and probability contexts, in a bottom-up mode. To each of these contexts corresponds an increasingly specific top-down priming effect on lower processing stages, mostly pattern recognition and discrimination. Contextual learning of time intervals, events' temporal order or sequential dependencies and events' prior probability results from the delivery of large stimuli sequences. This learning gives rise to emergent properties which closely match the experimental data.