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Distribuição espacial e relações alometricas de especies de Vochysiaceae em fragmentos de cerrado no municipio de Itirapina, São Paulo; Spatial pattern and allometry of Vochysiaceae species on fragments of cerrado vegetation, Itirapina, São Paulo, Brazil

Rafael Carvalho da Costa
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/12/2006 PT
Relevância na Pesquisa
46.08%
O domínio dos cerrados compreende uma grande variação de tipos vegetacionais, com fisionomias indo de campestres a florestais. Estas diferenças estão relacionadas a vários fatores ecológicos que podem ter influência em aspectos de populações vegetais como relações alométricas e padrão espacial. Comparações desses aspectos entre espécies são importantes na distinção entre diferentes estratégias de espécies do cerrado que as permitam ocupar tipos diferentes de habitats. Nesse sentido, este estudo analisou variações em 1) relações alométricas entre altura e diâmetro e 2) padrão espacial de espécies de Vochysiaceae, em fragmentos de cerrado de diferentes fisionomias. As espécies comparadas entre fragmentos, Qualea grandiflora Mart. e Vochysia tucanorum Mart, diferiram em plasticidade da relação entre altura e diâmetro entre fragmentos: Q. grandiflora apresentou diferenças de forma e V. tucanorum diferenças de tamanho. A variação de Q. grandiflora parece não ser resposta ao estresse causado pelo vento, pois as diferenças encontradas não corresponderam às ocorrências dos indivíduos em fisionomias abertas ou fechadas. As variações de V. tucanorum sugerem um efeito do estresse causado pelo vento...

Aspectos da historia de vida da especie de dossel Savia dictyocarpa Mull. Arg. (Phyllanthaceae) em um fragmento da floresta estacional semidecidua no Municipio de Campinas, SP; Life story aspects of the canopy species Savia dictyocarpa Mull. Arg. (Phyllanthaceae) in a seasonal semideciduous forest in Campinas municipallity, SP

Ligia Paulillo Sims
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/08/2009 PT
Relevância na Pesquisa
35.91%
O presente estudo investigou a estrutura de estádios ontogenéticos e espacial da espécie Savia dictyocarpa (Phyllanthaceae) na Mata Ribeirão Cachoeira, Campinas, SP. Essa espécie dióica é comum ocupante do dossel de florestas estacionais da região sudeste do Brasil e dada sua importância resolveu-se levantar informações sobre sua história de vida. Para tanto foram feitas duas questões centrais: 1) é possível definir os estádios ontogenéticos de S. dictyocarpa a partir da variação morfométrica e arquitetural que ocorre longo da vida da espécie? 2) qual distribuição espacial dos indivíduos ao longo da ontogenia dessa espécie e quais os fatores ambientais que influem na distribuição? Nos 0,5 hectares amostrados encontramos 194 indivíduos distribuídos em 5 estádios ontogenéticos: infantil, jovem, imaturo, adulto e senil. Não encontramos plântulas ou adultos reprodutivos nas parcelas, mas encontramos algumas plântulas. Portanto a definição do estádio plântula foi feita sem considerações sobre caracteres morfométricos. Os frutos encontrados não possuíam sementes, o que pode ser indicativo de ausência de polinização de flores, seja pela baixa freqüência de indivíduos masculinos ou pela ausência de polinizador. O padrão de ramificação apresentado é próprio do modelo arquitetural de Massart...

Heuristic pattern search for bound constrained minimax problems

Espírito Santo, I. A. C. P.; Fernandes, Edite Manuela da G. P.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Parte de Livro
Publicado em //2011 ENG
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This paper presents a pattern search algorithm and its hybridization with a random descent search for solving bound constrained minimax problems. The herein proposed heuristic pattern search method combines the Hooke and Jeeves (HJ) pattern and exploratory moves with a randomly generated approxi- mate descent direction. Two versions of the heuristic algorithm have been applied to several benchmark minimax problems and compared with the original HJ pat- tern search algorithm.

Viability of a random pattern dorsal skin flap, in diabetic rats

Carvalho,Eliziane Nitz de; Ferreira,Lydia Masako; Carvalho,Nestor Antônio Schmidt de; Abla,Luiz Eduardo Felipe; Liebano,Richard Eloin
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
Relevância na Pesquisa
46.01%
PURPOSE: Evaluation of the viability of a random pattern dorsal skin flap, in rats with experimentally induced diabetes mellitus. METHODS: Thirty adult, male, Wistar EPM rats were distributed, at random, in two groups: I - Control (flap elevation) and II - Experimental (flap elevation ten days after alloxan induced diabetes ). RESULTS: The mean areas of necrosis in the different groups were 36.4% (Control) and 52.1% (Experimental). CONCLUSION: The random pattern dorsal skin flap was less viable in the diabetic rats.

Capsaicin on the viability of random-pattern skin flaps in rats

Godoy,Gustavo Roberto de; Liebano,Richard Eloin; Corrêa,Juliana Barbosa; Hochman,Bernardo; Ferreira,Lydia Masako
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2010 EN
Relevância na Pesquisa
46.05%
PURPOSE: To evaluate the effects of capsaicin on the viability of ischemic random-pattern skin flaps in rats. METHODS:Forty EPM1-Wistar rats were randomized into two groups of 20 animals each, the capsaicin group and the control group. A random-pattern skin flap measuring 10 x 4cm was raised and a plastic barrier was placed between the flap and the donor site. After the surgical procedure, the control group was treated with an inert vehicle in the form of a cream applied uniformly to a rayon bandage which, in turn, was applied to the surface of the skin flap. The capsaicin group was treated in the same way, but in this case capsaicin was added to the cream. This procedure was repeated for two consecutive days. RESULTS: There was a significantly smaller amount of flap necrosis in the capsaicin group (35.07%) than in the control group (44.75%) (p=0.035). CONCLUSION:Topical administration of capsaicin improved the viability of ischemic random-pattern skin flaps in rats.

Adipose-derived stem cells (ADSC) in the viability of a random pattern dorsal skin flap in rats

Suartz,Caio Vinicius; Gaiba,Silvana; França,Jerônimo Pereira de; Aloise,Antonio Carlos; Ferreira,Lydia Masako
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
46.04%
PURPOSE: To evaluate the viability of random pattern dorsal skin flaps in rats after injection of adipose-derived stem cells (ADSC). METHODS: Thirty five adult male Wistar EPM rats (weight 250-300 g) were distributed, at random, in two groups. I- Control (flap elevation with injection of saline solution) with fifteen animals and II- Experimental (flap elevation with injection of ADSC ) with fifteen animal. The ADSC were isolated from others five adult male rats. A dorsal skin flap measuring 10x4 cm was raised and a plastic barrier was placed between the flap and its bed in both groups and the injection (cells or saline solution) were perfomed immediately after the surgery. The percentage of flap necrosis was measured on the seventh postoperative day. RESULTS: The ADSC were able to replicate in our culture conditions. We also induced their adipogenic, osteogenic and chondrogenic differentiation to verify their mesenchymal stem cells potentiality in vitro. The results were statistically significant showing that the ADSC decreased the area of necrosis (p<0.05). CONCLUSIONS: The cells demonstrated adipogenic, osteogenic and chondrogenic differentiation potential in vitro. The administration of adipose-derived stem cells was effective to increase the viability of the random random pattern dorsal skin flaps in rats.

Functional sensory function recovery of random-pattern abdominal skin flap in the repair of fingertip skin defects

YU, YA-DONG; ZHANG, YING-ZE; BI, WEI-DONG; WU, TAO
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.05%
The fingertip skin defect is a common hand injury often accompanied by tendon or bone exposure, and is normally treated with flaps. The aim of this study was to evaluate the functional sensory recovery of random-pattern abdominal skin flap in the repair of fingertip cutaneous deficiency. A total of 23 patients, aged between 18 and 50 years (mean age, 31 years) with fingertip cutaneous deficiency (30 digits) were treated with random-pattern abdominal skin flaps. The post-debridement defect area measured from 0.7×1.2 to 2.5×3 cm. The flap pedicle was divided three weeks after surgery, which marked the onset of the second stage. A second surgery was performed on 2 patients after 3 months and on another set of 2 patients after 6 months to create a thinner flap. Tissue was dissected during surgery for a histological examination. All the flaps survived and the post-operative follow-up ranged from 2 weeks to 6 months. Patients were satisfied with the appearance of their fingers and the flaps. All flaps demonstrated satisfactory flexibility and texture and sensory recovery was achieved. Only 4 patients were subjected to a second surgery to make the flap thinner. The flaps for the 3-month tissue section had several low-density, free nerve endings...

Can environmental constraints determine random patterns of plant species co-occurrence?

García-Baquero, Gonzalo; Crujeiras, Rosa M
Fonte: BlackWell Publishing Ltd Publicador: BlackWell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.08%
Plant community ecologists use the null model approach to infer assembly processes from observed patterns of species co-occurrence. In about a third of published studies, the null hypothesis of random assembly cannot be rejected. When this occurs, plant ecologists interpret that the observed random pattern is not environmentally constrained – but probably generated by stochastic processes. The null model approach (using the C-score and the discrepancy index) was used to test for random assembly under two simulation algorithms. Logistic regression, distance-based redundancy analysis, and constrained ordination were used to test for environmental determinism (species segregation along environmental gradients or turnover and species aggregation). This article introduces an environmentally determined community of alpine hydrophytes that presents itself as randomly assembled. The pathway through which the random pattern arises in this community is suggested to be as follows: Two simultaneous environmental processes, one leading to species aggregation and the other leading to species segregation, concurrently generate the observed pattern, which results to be neither aggregated nor segregated – but random. A simulation study supports this suggestion. Although apparently simple...

Formation of white-eye pattern with microdischarge in an air dielectric barrier discharge system

He, Yafeng; Dong, Lifang; Liu, Weili; Wang, Hongfang; Zhao, Zengchao; Fan, Weili
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 26/02/2011
Relevância na Pesquisa
35.9%
We report on the first observation of white-eye pattern in an air dielectric barrier discharge. The patterned discharges undergo a development as following: random spots - quasihexagonal pattern - hexagonal pattern (type I) - hexagonal pattern (type II) - white-eye pattern - chaos as the voltage is increased. The spatiotemporal characteristics of patterned discharges are investigated by using an optical method. Results show that the two discharge modes, uniform mode and filamentary mode, are actually two different spatial presentations of the same origin: the microdischarge. From the viewpoint of pattern dynamics, the white-eye pattern results from a 3-wave resonance interaction.; Comment: 8 pages, 4 figures

Forming A Random Field via Stochastic Cliques: From Random Graphs to Fully Connected Random Fields

Shafiee, Mohammad Javad; Wong, Alexander; Fieguth, Paul
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/06/2015
Relevância na Pesquisa
35.93%
Random fields have remained a topic of great interest over past decades for the purpose of structured inference, especially for problems such as image segmentation. The local nodal interactions commonly used in such models often suffer the short-boundary bias problem, which are tackled primarily through the incorporation of long-range nodal interactions. However, the issue of computational tractability becomes a significant issue when incorporating such long-range nodal interactions, particularly when a large number of long-range nodal interactions (e.g., fully-connected random fields) are modeled. In this work, we introduce a generalized random field framework based around the concept of stochastic cliques, which addresses the issue of computational tractability when using fully-connected random fields by stochastically forming a sparse representation of the random field. The proposed framework allows for efficient structured inference using fully-connected random fields without any restrictions on the potential functions that can be utilized. Several realizations of the proposed framework using graph cuts are presented and evaluated, and experimental results demonstrate that the proposed framework can provide competitive performance for the purpose of image segmentation when compared to existing fully-connected and principled deep random field frameworks.; Comment: 8 pages

Bilinear Random Projections for Locality-Sensitive Binary Codes

Kim, Saehoon; Choi, Seungjin
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 02/06/2015
Relevância na Pesquisa
35.93%
Locality-sensitive hashing (LSH) is a popular data-independent indexing method for approximate similarity search, where random projections followed by quantization hash the points from the database so as to ensure that the probability of collision is much higher for objects that are close to each other than for those that are far apart. Most of high-dimensional visual descriptors for images exhibit a natural matrix structure. When visual descriptors are represented by high-dimensional feature vectors and long binary codes are assigned, a random projection matrix requires expensive complexities in both space and time. In this paper we analyze a bilinear random projection method where feature matrices are transformed to binary codes by two smaller random projection matrices. We base our theoretical analysis on extending Raginsky and Lazebnik's result where random Fourier features are composed with random binary quantizers to form locality sensitive binary codes. To this end, we answer the following two questions: (1) whether a bilinear random projection also yields similarity-preserving binary codes; (2) whether a bilinear random projection yields performance gain or loss, compared to a large linear projection. Regarding the first question...

Banzhaf Random Forests

Sun, Jianyuan; Zhong, Guoqiang; Dong, Junyu; Cai, Yajuan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/07/2015
Relevância na Pesquisa
35.91%
Random forests are a type of ensemble method which makes predictions by combining the results of several independent trees. However, the theory of random forests has long been outpaced by their application. In this paper, we propose a novel random forests algorithm based on cooperative game theory. Banzhaf power index is employed to evaluate the power of each feature by traversing possible feature coalitions. Unlike the previously used information gain rate of information theory, which simply chooses the most informative feature, the Banzhaf power index can be considered as a metric of the importance of each feature on the dependency among a group of features. More importantly, we have proved the consistency of the proposed algorithm, named Banzhaf random forests (BRF). This theoretical analysis takes a step towards narrowing the gap between the theory and practice of random forests for classification problems. Experiments on several UCI benchmark data sets show that BRF is competitive with state-of-the-art classifiers and dramatically outperforms previous consistent random forests. Particularly, it is much more efficient than previous consistent random forests.; Comment: arXiv admin note: text overlap with arXiv:1302.4853 by other authors

Formation of a New Class of Random Fractals in Fragmentation with Mass Loss

Hassan, M. K.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.91%
We consider the fragmentation process with mass loss and discuss self-similar properties of the arising structure both in time and space focusing on dimensional analysis. This exhibits a spectrum of mass exponents $\theta$, whose exact numerical values are given for which $x^{-\theta}$ or $t^{\theta z}$ has the dimension of particle size distribution function c(x,t) where z is the kinetic exponent. We also give explicit scaling solution for special case. Finally, we identify a new class of fractals ranging from random to non-random and show that the fractal dimension increases with increasing order and a transition to strictly self-similar pattern occurs when randomness is completely seized.; Comment: 5 pages, Latex, no Figures, bibliography updated and minor corrections to text in this version

Generation and Analysis of Constrained Random Sampling Patterns

Pierzchlewski, Jacek; Arildsen, Thomas
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.15%
Random sampling is a technique for signal acquisition which is gaining popularity in practical signal processing systems. Nowadays, event-driven analog-to-digital converters make random sampling feasible in practical applications. A process of random sampling is defined by a sampling pattern, which indicates signal sampling points in time. Practical random sampling patterns are constrained by ADC characteristics and application requirements. In this paper authors introduce statistical methods which evaluate random sampling pattern generators with emphasis on practical applications. Furthermore, the authors propose a new random pattern generator which copes with strict practical limitations imposed on patterns, with possibly minimal loss in randomness of sampling. The proposed generator is compared with existing sampling pattern generators using the introduced statistical methods. It is shown that the proposed algorithm generates random sampling patterns dedicated for event-driven-ADCs better than existed sampling pattern generators. Finally, implementation issues of random sampling patterns are discussed.; Comment: 29 pages, 12 figures, submitted to Circuits, Systems and Signal Processing journal

Spatial patterns of competing random walkers

Hernandez-Garcia, Emilio; Heinsalu, Els; Lopez, Cristobal
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.98%
We review recent results obtained from simple individual-based models of biological competition in which birth and death rates of an organism depend on the presence of other competing organisms close to it. In addition the individuals perform random walks of different types (Gaussian diffusion and L\'{e}vy flights). We focus on how competition and random motions affect each other, from which spatial instabilities and extinctions arise. Under suitable conditions, competitive interactions lead to clustering of individuals and periodic pattern formation. Random motion has a homogenizing effect and then delays this clustering instability. When individuals from species differing in their random walk characteristics are allowed to compete together, the ones with a tendency to form narrower clusters get a competitive advantage over the others. Mean-field deterministic equations are analyzed and compared with the outcome of the individual-based simulations.; Comment: 38 pages, including 6 figures

Pattern Formation on Networks with Reactions: A Continuous Time Random Walk Approach

Angstmann, Christopher N.; Donnelly, Isaac C.; Henry, Bruce I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.99%
We derive the generalized master equation for reaction-diffusion on networks from an underlying stochastic process, the continuous time random walk (CTRW). The non-trivial incorporation of the reaction process into the CTRW is achieved by splitting the derivation into two stages. The reactions are treated as birth-death processes and the first stage of the derivation is at the single particle level, taking into account the death process, whilst the second stage considers an ensemble of these particles including the birth process. Using this model we have investigated different types of pattern formation across the vertices on a range of networks. Importantly, the CTRW defines the Laplacian operator on the network in a non \emph{ad-hoc} manner and the pattern formation depends on the structure of this Laplacian. Here we focus attention on CTRWs with exponential waiting times for two cases; one in which the rate parameter is constant for all vertices and the other where the rate parameter is proportional to the vertex degree. This results in nonsymmetric and symmetric CTRW Laplacians respectively. In the case of symmetric Laplacians, pattern formation follows from the Turing instability. However in nonsymmetric Laplacians, pattern formation may be possible with or without a Turing instability.; Comment: 27 pages...

Multiple scale landscape pattern index interpretation for the persistent monitoring of land-cover and land-use

Spivey, Alvin
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Dissertação
EN_US
Relevância na Pesquisa
35.9%
Mapping land-cover land-use change (LCLUC) over regional and continental scales, and long time scales (years and decades), can be accomplished using thematically identified classification maps of a landscape--a LCLU class map. Observations of a landscape's LCLU class map pattern can indicate the most relevant process, like hydrologic or ecologic function, causing landscape scale environmental change. Quantified as Landscape Pattern Metrics (LPM), emergent landscape pat- terns act as Landscape Indicators (LI) when physically interpreted. The common mathematical approach to quantifying observed landscape scale pattern is to have LPM measure how connected a class exists within the landscape, through nonlinear local kernel operations of edges and gradi- ents in class maps. Commonly applied kernel-based LPM that consistently reveal causal processes are Dominance, Contagion, and Fractal Dimension. These kernel-based LPM can be difficult to interpret. The emphasis on an image pixel's edge by gradient operations and dependence on an image pixel's existence according to classification accuracy limit the interpretation of LPM. For example, the Dominance and Contagion kernel-based LPM very similarly measure how connected a landscape is. Because of this...

Impacts of Genetic Algorithm Parameters on the Solution Performance for the Uniform Circular Antenna Array Pattern Synthesis Problem

Yaman,F.; Yilmaz,A. E.
Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
35.91%
In this paper, the uniform circular antenna array pattern synthesis problem is solved by means of the real coded genetic algorithm (GA). At the same time, the impacts of the mutation rate and the crossover position on the GA performance are also investigated. For this purpose, a circular antenna array with uniformly spaced isotropic elements having identical excitation amplitudes is used as a model. Unlike the conventional GA (with fixed mutation rate and random crossover positions), typical GA implementations with variable mutation rate and restricted crossover position are considered for performance improvement. In conclusion, for the specific problem, decreasing mutation rate with negative derivative is observed to be outperforming the implementations with different mutation rate behaviors. Moreover, regarding the crossover technique, it is observed that imposing some restrictions on the crossover positions (rather than fully random position selection) yields better solutions.

Image encryption based on phase encoding by means of a fringe pattern and computational algorithms

Muñoz Rodriguez,J. A.; Rodríguez-Vera,R.
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2006 EN
Relevância na Pesquisa
36%
A computational technique for image encryption and decryption is presented. The technique is based on light reflection, intensity superposition and computational algorithms. The image to be encrypted is a reflectance map obtained by means of the light reflected by a scene. To perform the encryption procedure, the image is encoded in a computer-generated fringe pattern. The model of the fringe pattern is a cosine function, which adds to its argument the image to be encrypted as a phase. It generates a fringe pattern deformed according to the image. To complete the encryption, a random mask is superimposed on the fringe pattern. The decryption procedure is performed by subtracting the random mask from the encrypted image and applying a phase recovery method. To retrieve the phase from the fringe pattern, the heterodyne demodulation method is used. To describe the accuracy of results of the decrypted images and the robustness of the encryption, a root mean square of error is calculated. All steps of the encryption and decryption are performed in computational form. The results of encryption and decryption are thus improved. It represents a contribution to the field of encryption and decryption. This technique is tested with simulated images and real images...

The random neural network model on the color pattern recognition problem

Aguilar,José
Fonte: Facultad de Ingeniería, Universidad del Zulia Publicador: Facultad de Ingeniería, Universidad del Zulia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2005 EN
Relevância na Pesquisa
35.95%
The purpose of this paper is to describe the use of the multiple classes random neural network model to recognize patterns having different colors. We propose a learning algorithm for the recognition of color patterns based upon the non-linear equations of the multiple classes random neural network model using gradient descent of a quadratic error function. In addition, we propose a progressive retrieval process with adaptive threshold value. The experimental evaluation shows that our approach provides good results.