Growing neural gas as a memory mechanism of a heuristic to solve a community detection problem in networks

Iterative heuristics are commonly used to address combinatorial optimization problems. However, to meet both robustness and efficiency with these methods when their iterations are independent, it is necessary to consider a high number of iterations or to include local search-based strategies in them. Both approaches are very time-consuming and, consequently, not efficient for medium and large-scale instances of combinatorial optimization problems. In particular, the community detection problem in networks is well-known due to the instances with hundreds to thousands of vertices. In the literature, the heuristics to detect communities in networks that use a local search are those that achieve the partitions with the best solution values. Nevertheless, they are not suitable to tackle medium to large scale networks. This paper presents an adaptive heuristic, named GNGClus, that uses the neural network Growing Neural Gas to play the role of memory mechanism. The computational experiment with LFR networks indicates that the proposed strategy significantly outperformed the same solution method with no memory mechanism. In addition, GNGClus was very competitive with a version of the heuristic that employs an elite set of solutions to guide the solution search. (C) 2016 The Authors. Published by Elsevier B.V.Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo (UNIFESP) Av. Cesare M. G. Lattes, 1201, Eugênio de Mello, São José dos Campos-SP, CEP: 12247-014, BrasilInstituto de Ciência e Tecnologia, Universidade Federal de São Paulo (UNIFESP) Av. Cesare M. G. Lattes, 1201, Eugênio de Mello, São José dos Campos-SP, CEP: 12247-014, BrasilWeb of Scienc

Improving the connectivity of community detection-based hierarchical routing protocols in large-scale wsns

The recent growth in the use of wireless sensor networks (WSNs) in many applications leads to the raise of a core infrastructure for communication and data gathering in Cyber-Physical Systems (CPS). The communication strategy in most of the WSNs relies on hierarchical clustering routing protocols due to their ad hoc nature. In the bulk of the existing approaches some special nodes, named Cluster-Heads (CHs), have the task of assembling clusters and intermediate the communication between the cluster members and a central entity in the network, the Sink. Therefore, the overall efficiency of such protocols is highly dependent on the even distribution of CHs in the network. Recently, a community detection-based approach, named RLP, have shown interesting results with respect to the CH distribution and availability that potentially increases the overall WSN efficiency. Despite the better results of RLP regarding the literature, the adopted CH election algorithm may lead to a CH shortage throughout the network operation. In line with that, in this paper, we introduce an improved version of RLP, named HRLP. Our proposal includes a hybrid CH election algorithm which relies on a computationally cheap and distributed probabilistic-based CH recovery procedure to improve the network connectivity. Additionally, we provide a performance analysis of HRLP and its comparison to other protocols by considering a large-scale WSN scenario. The results evince the improvements achieved by the proposed strategy by means of the network connectivity and lifetime metrics. (C) 2016 The Authors. Published by Elsevier B.V.Federal University of São Paulo, Avenida Cesare Mansueto Giulio Lattes, 1201, Parque Tecnológico, 12247014, São José dos Campos-SP-BrazilFederal University of São Paulo, Avenida Cesare Mansueto Giulio Lattes, 1201, Parque Tecnológico, 12247014, São José dos Campos-SP-BrazilWeb of Scienc

A Hybrid Heuristic for the k-medoids Clustering Problem

Clustering is an important tool for data analysis, since it allows the exploration of datasets with no or very little prior information. Its main goal is to group a set of data based on their similarity (dissimilarity). A well known mathematical formulation for clustering is the k-medoids problem. Current versions of k-medoids rely on heuristics, with good results reported in the literature. However, few methods that analyze the quality of the partitions found by the heuristics have been proposed. in this paper, we propose a hybrid Lagrangian heuristic for the k-medoids. We compare the performance of the proposed Lagrangian heuristic with other heuristics for the k-medoids problem found in literature. Experimental results presented that the proposed Lagrangian heuristic outperformed the other algorithms.UNIFESP, Inst Ciencia & Tecnol, BR-12230280 Sao Jose Dos Campos, SP, BrazilUNIFESP, Inst Ciencia & Tecnol, BR-12230280 Sao Jose Dos Campos, SP, BrazilWeb of Scienc

Community detection by consensus genetic-based algorithm for directed networks

Finding communities in networks is a commonly used form of network analysis. There is a myriad of community detection algorithms in the literature to perform this task. In spite of that, the number of community detection algorithms in directed networks is much lower than in undirected networks. However, evaluation measures to estimate the quality of communities in undirected networks nowadays have its adaptation to directed networks as, for example, the well-known modularity measure. This paper introduces a genetic-based consensus clustering to detect communities in directed networks with the directed modularity as the fitness function. Consensus strategies involve combining computational models to improve the quality of solutions generated by a single model. The reason behind the development of a consensus strategy relies on the fact that recent studies indicate that the modularity may fail in detecting expected clusterings. Computational experiments with artificial LFR networks show that the proposed method was very competitive in comparison to existing strategies in the literature. (C) 2016 The Authors. Published by Elsevier B.V.Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo (UNIFESP) Av. Cesare M. G. Lattes, 1201, Eugênio de Mello, São José dos Campos-SP, CEP: 12247-014, BrasilInstituto de Ciência e Tecnologia, Universidade Federal de São Paulo (UNIFESP) Av. Cesare M. G. Lattes, 1201, Eugênio de Mello, São José dos Campos-SP, CEP: 12247-014, BrasilWeb of Scienc

Produção simultânea de -fructofuranosidase e fructo-oligossacarídeos por Penicillium citreonigrum URM 4459

O objetivo deste trabalho foi a produção simultânea de -Frutofuranosidase (FFase) e frutooligossacarídeos (FOS) por P. citreonigrum utilizando um planejamento fatorial completo. Para isso, o fungo foi cultivado em meio rico em sacarose (20% p/v) a 150 rpm. As condições de tempo de fermentação, temperatura, pH e concentração de extrato de levedura foram definidas utilizando um planejamento fatorial. Ao fim da fermentação, o sobrenadante obtido por filtração foi utilizado para quantificação de FFase e FOS. Todas as variáveis independentes estudadas exerceram efeito estatisticamente significativo sob a produção de FFase. Por outro lado, apenas as variáveis tempo de fermentação e temperatura exerceram efeito significativo sob a produção do FOS. As condições ideais para produção simultânea de FFase e FOS foram obtidas na região dos pontos centrais, onde obteve-se uma produção média de 93,49 g/L de FOS e uma atividade de 260,40 U/mL de FFase

Wheezing in infants: frequency, clinical characteristics and treatment

OBJECTIVE: To estimate the frequency and describe the clinical characteristics and respective treatments of previous history of wheezing. METHODS: Infants aged 6-23 months with upper respiratory tract complaints and reporting previous wheezing were followed-up retrospectively. Data were registered on a validated standardized form. RESULTS: Out of 451 infants, 164 (36.4%; 95%CI: 31.9-41.0) had a report of prior history of wheezing, 148 (32.8%; 95%CI: 28.5-37.4) during the first year of life. The mean age at the first episode of wheezing was 5.3±3.9 months. Among those who had had their first episode before 12 months of age, 38.5% reported 3 to 6 episodes and 14.2% > 6 episodes. Mean age at first episode was lower for those with > 3 episodes in comparison with those with seis episódios. A média da idade no primeiro episódio foi menor para os que apresentaram > três episódios em comparação aos que apresentaram até dois episódios (3,2±2,7 versus 5,7±2,5 meses, p < 0,001). CONCLUSÃO: Um terço dos lactentes apresentou chiado no primeiro ano de vida. Quanto mais cedo ocorre o primeiro episódio, mais frequente é a recorrência do chiado.Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal da Bahia Faculdade de Medicina da Bahia Programa de Pós-Graduação em Ciências da SaúdeUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de PediatriaUniversidade de São Paulo Faculdade de Saúde Pública Departamento de EpidemiologiaEscola Bahiana de Medicina e Saúde PúblicaUFBAUFBA Faculdade de Medicina da Bahia Departamento de Anatomia Patológica e Medicina LegalUFBA Faculdade de Medicina da Bahia Departamento de PediatriaUNIFESP, EPM, Depto. de PediatriaSciEL

Protocolo para congelamento e descongelamento do sêmen de tambaqui em macropalhetas.

O tambaqui tem sido alvo de diversos estudos relacionados à criopreservação seminal, tanto para dar suporte ao programa de melhoramento genético atualmente em andamento, quanto para o uso em escala comercial. Apesar da existência de alguns protocolos de criopreservação de sêmen do tambaqui em palhetas, ainda há a necessidade de estudos com outros recipientes com maior capacidade de armazenamento visando à consolidação da técnica para a aplicação em escala comercial. O objetivo do presente estudo foi estabelecer um protocolo de criopreservação seminal do tambaqui em macropalhetas de 4,0 mL, a partir da definição de um meio diluidor, tempo de equilíbrio e a melhor relação temperatura/tempo no descongelamento do sêmen. No experimento 1, amostras de sêmen foram diluídas em seis meios diluidores preparados a partir da combinação do crioprotetor metilglicol (5, 10 ou 15%) e gema de ovo (0 ou 5). Após a diluição, o sêmen permaneceu em contato com cada meio diluidor durante 4, 20 ou 40 minutos (tempo de equilíbrio) antes do início do congelamento. No experimento 2, foi avaliada a influência da temperatura e tempo de descongelamento na qualidade seminal do tambaqui. Para isso, amostras de sêmen congeladas foram descongeladas em banho-maria nos seguintes tratamentos: 30ºC por 50s (T1) e 80s (T2) e 60ºC por 25s (T3) e 40s (T4). Melhores resultados de cinética espermática foram obtidos com o sêmen diluído no meio composto por 5% de metilglicol acrescido de 5% de gema de ovo, o qual deve ser congelado 4 min após a diluição (motilidade total - 60%). O descongelamento a 60°/25s apresentou melhores resultados de motilidade total (55%) que os protocolos 30°C/50s, 30°/80s e 60°/50s (temperatura/tempo). Ao final do estudo concluiu-se que o protocolo ideal para criopreservação do sêmen do tambaqui em macropalhetas de 4,0 mL consiste na diluição do sêmen na proporção de 1:9 (v:v) em um meio diluidor composto por 5% de metilglicol e 5% de gema de ovo, os quais devem permanecer em contato por 4 minutos até que sejam submetidos ao processo de congelamento em botijão dry-shipper. O descongelamento das amostras deve ser realizado em banho-maria a 60°C por 25s

Infection by Streptococcus pneumoniae in children with or without radiologically confirmed pneumonia

ObjectiveCommunity-acquired pneumonia is an important cause of morbidity in childhood, but the detection of its causative agent remains a diagnostic challenge. The authors aimed to evaluate the role of the chest radiograph to identify cases of community-aquired pneumonia caused by typical bacteria.MethodsThe frequency of infection by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis was compared in non-hospitalized children with clinical diagnosis of community acquired pneumonia aged 2–59 months with or without radiological confirmation (n = 249 and 366, respectively). Infection by S. pneumoniae was diagnosed by the detection of a serological response against at least one of eight pneumococcal proteins (defined as an increase ≥2-fold in the IgG levels against Ply, CbpA, PspA1 and PspA2, PhtD, StkP-C, and PcsB-N, or an increase ≥1.5-fold against PcpA). Infection by H. influenzae and M. catarrhalis was defined as an increase ≥2-fold on the levels of microbe-specific IgG.ResultsChildren with radiologically confirmed pneumonia had higher rates of infection by S. pneumoniae. The presence of pneumococcal infection increased the odds of having radiologically confirmed pneumonia by 2.8 times (95% CI: 1.8–4.3). The negative predictive value of the normal chest radiograph for infection by S. pneumoniae was 86.3% (95% CI: 82.4–89.7%). There was no difference on the rates of infection by H. influenzae and M. catarrhalis between children with community-acquired pneumonia with and without radiological confirmation.ConclusionsAmong children with clinical diagnosis of community-acquired pneumonia submitted to chest radiograph, those with radiologically confirmed pneumonia present a higher rate of infection by S. pneumoniae when compared with those with a normal chest radiograph.</p