Beyond the average: Detecting global singular nodes from local features in complex networks

Deviations from the average can provide valuable insights about the organization of natural systems. The present article extends this important principle to the systematic identification and analysis of singular motifs in complex networks. Six measurements quantifying different and complementary features of the connectivity around each node of a network were calculated, and multivariate statistical methods applied to identify singular nodes. The potential of the presented concepts and methodology was illustrated with respect to different types of complex real-world networks, namely the US air transportation network, the protein-protein interactions of the yeast Saccharomyces cerevisiae and the Roget thesaurus networks. The obtained singular motifs possessed unique functional roles in the networks. Three classic theoretical network models were also investigated, with the Barabasi-Albert model resulting in singular motifs corresponding to hubs, confirming the potential of the approach. Interestingly, the number of different types of singular node motifs as well as the number of their instances were found to be considerably higher in the real-world networks than in any of the benchmark networks. Copyright (C) EPLA, 2009

The effects of 2 levels of the inspired oxygen fraction on blood gas variables in propofol-anesthetized dogs with high intracranial pressure

The influence of 2 different levels of the inspired oxygen fraction (FiO(2)) on blood gas variables was evaluated in dogs with high intracranial pressure (ICP) during propofol anesthesia (induction followed by a continuous rate infusion [CRI] of 0.6 mg/kg/min) and intermittent positive pressure ventilation (IPPV). Eight adult mongrel dogs were anesthetized on 2 occasions, 21 d apart, and received oxygen at an FiO(2) of 1.0 (G100) or 0.6 (G60) in a randomized crossover fashion. A fiberoptic catheter was implanted on the surface of the right cerebral cortex for assessment of the ICP. An increase in the ICP was induced by temporary ligation of the jugular vein 50 min after induction of anesthesia and immediately after baseline measurement of the ICP. Blood gas measurements were taken 20 min later and then at 15-min intervals for 1 h. Numerical data were submitted to Morrison's multivariate statistical methods. The ICP, the cerebral perfusion pressure and the mean arterial pressure did not differ significantly between FiO(2) levels or measurement times after jugular ligation. The only blood gas values that differed significantly (P < 0.05) were the arterial oxygen partial pressure, which was greater with G100 than with G60 throughout the procedure, and the venous haemoglobin saturation, that was greater with G100 than with G60 at M0. There were no significant differences between FiO(2) levels or measurement times in the following blood gas variables: arterial carbon dioxide partial pressure, arterial hemoglobin saturation, base deficit, bicarbonate concentration, pH, venous oxygen partial pressure, venous carbon dioxide partial pressure and the arterial-to-end-tidal carbon dioxide difference.

Utilização de métodos estatísticos multivariados na caracterização do mosaico sucessional em floresta semidecídual

O presente trabalho objetivou verificar a possibilidade da utilização de métodos estatísticos multivariados na caracterização das fases do desenvolvimento do mosaico sucessional de um trecho de floresta estacional semidecidual, através de variáveis estruturais. Foram alocadas parcelas de 10 m x 10 m, em que se procedeu à análise estrutural, ou seja, levantamento fitossociológico acrescido das variáveis Porcentagem de Cobertura (PC), Altura do Dossel (AD) e Cobertura por Lianas (CL). Os métodos estatísticos empregados foram Análise de Componentes Principais e Análise de Agrupamento, mais especificamente Classificação Hierárquica Ascendente. O primeiro componente principal explicou 43,96% da variância total, enquanto o segundo, 25,66%. As variáveis Área Basal (AB), Diâmetro Médio (DM) e Dominância Média (DOM) apresentaram correlações positivas entre si superiores a 0,75, podendo ser DM e DOM consideradas como um grupo de variáveis. As variáveis Número de Indivíduos (NI) e Número de Espécies (NE) apresentaram correlação 0,60, enquanto AD, CL e PC baixas correlações com as demais, indicando a importância da inclusão destas na análise. A classificação hierárquica e a partição dos grupos em quatro foram feitas considerando os dois primeiros eixos fatoriais. Os resultados indicaram dois comportamentos diferenciados: 1) valores baixos para AD e AB: Grupo 1, com valores baixos também para NI, NE e PC (fase de clareira); e Grupo 2, com valores elevados para NI e CL e baixos para DOM e DM (fase de construção); e 2) valores altos para AD e AB: Grupo 3, com valores altos também para NI, NE e PC e valor baixo para CL (fase madura); e Grupo 4, com valores elevados para DOM e DM e mais baixos para CL (fase de degradação). Os métodos estatísticos multivariados permitiram caracterizar as fases do desenvolvimento do mosaico sucessional, através das variáveis estruturais. A forma como foram estimadas as variáveis AD, CL e PC, porém, deve ser aprimorada, assim como é preciso incluir variáveis que discriminem melhor cada fase.

Parametria da associação do midazolam ou diazepam em cães pré-tratados pela atropina e tratados pela dexmedetomidina e quetamina

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

Agrupamento de países segundo indicadores de padrão de vida

Foram estudados 125 países avaliados por um conjunto de 26 indicadores básicos, de saúde, econômicos e educacionais, usando-se três métodos estatísticos multivariados: Análise de Agrupamento, Análise de Componentes Principais e Análise de Variância Multivariada. As variáveis mais discriminatórias foram a expectativa de vida, as taxas de mortalidade infantil e de menores de cinco anos, as taxas de natalidade e de fertilidade e a taxa de matrícula no segundo grau para o sexo feminino. Os países foram ordenados de acordo com um índice de padrão de vida e separados em cinco grupos.

Knowledge-based risk management: Survey on Brazilian software development enterprises

A risks management, carried on in an effective way, leads the software development to success and may influence on the organization. The knowledge takes part of such a process as a way to help taking decisions. This research aimed to analyze the use of Knowledge Management techniques to the Risk Management in software projects development and the possible influence on the enterprise revenue. It had, as its main studying subject, Brazilian incubated and graduated software developing enterprises. The chosen research method was the Survey type. Multivariate statistical methods were used for the treatment and analysis of the obtained results, this way identifying the most significant factors, that is, enterprise's achievement constraining factors and those outcome achievement ones. Among the latter we highlight the knowledge methodology, the time of existence of the enterprise, the amount of employees and the knowledge externalization. The results encourage contributing actions to the increasing of financial revenue. © 2013 Springer-Verlag.

Revisão sistemática e filogeografia de Deconychura longicauda (Aves - Dendrocolaptidae)

Os limites interespecíficos da espécie politípica Deconychura longicauda (Dendrocolaptidae) foram investigados por uma análise conjunta, incluindo caracteres moleculares, morfológicos e vocais. Um total de 1.108 pares de bases de genes mitocondriais Cit b e ND2 foram usados para construir hipóteses filogenéticas, ao passo que os caracteres morfológicos e vocais foram analisados com métodos estatísticos univariado e multivariado. Todas as árvores filogenéticas recuperadas indicam altos níveis de diferenciação genética e estrutura filogeográfica em Deconychura longicauda, com o reconhecimento de quatro grupos principais bem apoiados, geograficamente constituídos por aves (1) do centro de endemismo Guiana no nordeste da América do Sul (2), da bacia amazônica excluindo o escudo das Guianas (3), do sopé oriental dos Andes, e (4), trans-Andinas da América do Sul e América Central. O nível de divergência genética entre estes clados varia de 6-8% (entre as aves Guianenses, não-Guianenses, do sopé dos Andes e trans-Andinas). Embora os caracteres morfológicos contribuam pouco para a diagnose em Deconychura, o canto, por outro lado, consistetemente os distinguem. Nós recomendamos com base, principalmente, em sua diagnose molecular e vocal o desdobramento de D. longicauda nas seguintes espécies filogenéticas e biológicas: Deconychura longicauda, D. pallida, D. zimmeri, D. connectens, D. typica e um táxon ainda não nomeado, endêmico do sopé oriental dos Andes.

Estrutura das comunidades de peixes na bacia do rio Iguatemi-MS

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Variabilidade da frequência cardíaca e a dinâmica miocárdica em cães com degeneração mixomatosa da valva mitral submetidos a um programa de condicionamento físico

Pós-graduação em Medicina Veterinária - FCAV

Grouping of countries according to indicators of standard of living

The position of 125 countries is studied on the basis of a collection of 26 basic, health, economic and educational indicators. Multivariate statistical methods were used, including Cluster Analysis, Principal Component Analysis and Multivariate Analysis of Variance. The most discriminating variables were life expectancy the child mortality rate, the mortality rate of children of less than five years of age, the birth and fertility rates and the high-school female matriculation rate. The first principal component was interpreted as a measure of the living standard which made it possible to place the countries in order. Five clusters of countries are suggested.

Indicadores morfométricos: uma ferramenta no diagnóstico da vulnerabilidade ambiental

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Identifizierung und Charakterisierung von Protein-Biomarkern beim Glaukom

Das Glaukom ist, nach dem Katarakt, die zweithäufigste Ursache für Erblindungen weltweit mit Milionen von Betroffenen, die von dieser zunächst weitgehend symptomfreien neurodegenerativen Erkrankung heimgesucht werden. Die Möglichkeiten auf dem Feld der Diagnose beschränken sich bislang weitestgehend auf die Messung des Augeninnendrucks und der Beurteilung des Augenhintergrundes durch einen erfahrenen Augenarzt. Eine labordiagnostische Prophylaxe ist bis heute nicht verfügbar, die Zahl unerkannter Erkrankungen dementsprechend hoch. Hierdurch geht wertvolle Zeit verloren, die man für eine effektive Therapie nutzen könnte.rnBezüglich der Pathogenese des Glaukoms geht man heute von mehreren, miteinander wechselwirkenden Pathomechanismen aus, zu denen neben mechanischen Einflüssen durch einen erhöhten IOD auch Hypoxie, verminderte Neutrophinversorgung, Exzitotoxizität, oxidativer Stress und eine Beteiligung autoimmuner Prozesse gezählt werden. Unabhängig vom Pathomechanismus folgt stets die Etablierung umfangreicher degenerativer Prozesse im Sehnervenkopf, den retinalen Ganglienzellen und den Axonen des Sehnerven, die letztlich im irreversiblen Untergang dieser Neuronen münden. Diese pathologischen Prozesse im ZNS hinterlassen auf Proteomebene Spuren, die mithilfe moderner massenspektrometrischer Methoden in Kombination mit multivariaten statistischen Methoden detektierbar und als sogenannte Biomarker-Kandidaten mit definiertem Molekulargewicht darstellbar sind. In dieser Arbeit wurde ein „Workflow“ entwickelt, der es ermöglicht, diese Biomarker-Kandidaten im Blutserum und in der Tränenflüssigkeit in einfachen, reproduzierbaren Schritten zu identifizieren und zu charakterisieren. Abweichend von der etablierten Methotik der Bottom-Up-Proteomics musste hierfür eine Methode entsprechend einer Top-Down-Philosophie entwickelt werden, die es erlaubt, die Spuren des Glaukoms im Proteom zu detektieren und zu charakterisieren.rnDies erfolgte in dieser Arbeit durch sowohl massenspektroskopischen Methoden wie SELDI-TOF® und MALDI-Tof-Tof als auch durch Bead-, Gel- und Flüssigkeits-chromatographisch-basierte Separations und Fraktionierungstechniken.rnDie erfolgreiche Kombination dieser Methoden führte zu Identifikationen einer ganzen Reihe von Biomarker-Kandidaten. Unter den identifizierten Proteinen, die bezüglich ihres korrespondierenden SELDI-Peaks im Massenbereich von Biomarker-Kandidaten liegen, finden sich Zytokine und Effektormoleküle der angeborernen Immunität, stressinduzierbare Kinasen, Faktoren, die zum Schutz der Telomeren dienen, Proliferationsmarker, neuronale Antigene und Transportproteine. Darüber hinaus wurden Komponenten identifiziert, die an der neuronalen Neutrophinversorgung beteiligt sind, neuronale Rezeptoren und Antigene, Komponenten des Komplementsystems und des MHC-I-Komplexes. All diese identifizierten Proteine sind bezüglich ihrer Funktion und möglichen Rolle innerhalb der Pathogenese des Glaukoms detailliert beschrieben und charakterisiert. Dies erlaubt einen umfassenden Einblick in alle Pathomechanismen, denen nach heutigem Kenntnisstand, eine Rolle an der Pathogenese des Glaukoms unterstellt wird.rn

Intra-population variation and geographic correlation in Canthon humectus hidalgoensis using FTIR-ATR spectroscopy

In some cases external morphology is not sufficient to discern between populations of a species, as occurs in the dung beetle Canthon humectus hidalgoensis Bates; and much less to determine phenotypic distances between them. FTIR-ATR spectroscopy show several advantages over other identification techniques (e.g. morphological, genetic, and cuticular hydrocarbons analysis) due to the non-invasive manner of the sample preparation, the relative speed of sample analysis and the low-cost of this technology. The infrared spectrum obtained is recognized to give a unique ‘fingerprint’ because vibrational spectra are specific and unique to the molecular nature of the sample. In our study, results showed that proteins, amino acids and aromatic ethers of insect exocuticle have promising discriminative power to discern between different populations of C. h. hidalgoensis. Furthermore, the correlation between geographic distances between populations and the chemical distances obtained by proteins + amino acids + aromatic ethers was statistically significant, showing that the spectral and spatial information available of the taxa together with appropriated chemometric methods may help to a better understanding of the identity, structure, dynamics and diversity of insect populations.

Core derived downhole logs for holes CRP-2 and CRP-2A

In the northern McMurdo Sound (Ross Sea, Antarctica), the CRP-2/2A drillhole targeted the western margin of the Victoria Land Basin to investigate Neogene to Palaeogene climatic and tectonic history by obtaining continuous core and downhole logs. Well logging of CRP-2/2A has provided a complete and comprehensive dataset of in situ geophysical measurements. This paper describes the evaluation and interpretation of the downhole logging data using multivariate statistical methods. Two major types of multivariate statistical methods were each yielding a different perspective: (1) Factor analysis was used as an objective tool for classification of the drilled sequence based on physical and chemical properties. The factor logs are mirroring the basic geological controls (i.e., grain size, porosity, clay mineralogy) behind the measured geophysical properties, thereby making them easier to interpret geologically. (2) Cluster analysis of the logs groups similar downhole geophysical properties into one cluster, delineating individual logging or sedimentological units. These objectively and independently defined units, or statistical electrofacies, are helpful in differentiating lithological and sedimentological characterisations (e.g. grain size, provenance). The multivariate statistical methods of factor and cluster analysis proved to be powerful tools for fast, reliable, and objective characterisation of downhole geophysical properties at CRP-2/2A, resulting in interpretations which are consistent with sedimentological findings.

The identification of pathological subtypes of Alzheimer's disease using cluster analysis

A culster analysis was performed on 78 cases of Alzheimer's disease (AD) to identify possible pathological subtypes of the disease. Data on 47 neuropathological variables, inculding features of the gross brain and the density and distribution of senile plaques (SP) and neurofibrillary tangles (NFT) were used to describe each case. Cluster analysis is a multivariate statistical method which combines together in groups, AD cases with the most similar neuropathological characteristics. The majority of cases (83%) were clustered into five such groups. The analysis suggested that an initial division of the 78 cases could be made into two major groups: (1) a large group (68%) in which the distribution of SP and NFT was restricted to a relatively small number of brain regions, and (2) a smaller group (15%) in which the lesions were more widely disseminated throughout the neocortex. Each of these groups could be subdivided on the degree of capillary amyloid angiopathy (CAA) present. In addition, those cases with a restricted development of SP/NFT and CAA could be divided further into an early and a late onset form. Familial AD cases did not cluster as a separate group but were either distributed between four of the five groups or were cases with unique combinations of pathological features not closely related to any of the groups. It was concluded that multivariate statistical methods may be of value in the classification of AD into subtypes. © 1994 Springer-Verlag.