Analysis and Assembling of Network Structure in Mutualistic Systems

It has been observed that mutualistic bipartite networks have a nested structure of interactions. In addition, the degree distributions associated with the two guilds involved in such networks (e.g. plants & pollinators or plants & seed dispersers) approximately follow a truncated power law. We show that nestedness and truncated power law distributions are intimately linked, and that any biological reasons for such truncation are superimposed to finite size effects . We further explore the internal organization of bipartite networks by developing a self-organizing network model (SNM) that reproduces empirical observations of pollination systems of widely different sizes. Since the only inputs to the SNM are numbers of plant and animal species, and their interactions (i.e., no data on local abundance of the interacting species are needed), we suggest that the well-known association between species frequency of interaction and species degree is a consequence rather than a cause, of the observed network structure.Comment: J. of. Theor. Biology, in pres

Shock Tube Study of the Thermal Conductivity of Argon

Analysis of end-wall thermal boundary layer behind reflected shock to determine thermal conductivity of argon over temperatures 3150 to 9225

Colorectal cancer surgery in the very elderly patient: a systematic review of laparoscopic versus open colorectal resection.

INTRODUCTION: Colorectal cancer is the second most common cause of death from neoplastic disease in men and third in women of all ages. Globally, life expectancy is increasing, and consequently, an increasing number of operations are being performed on more elderly patients with the trend set to continue. Elderly patients are more likely to have cardiovascular and pulmonary comorbidities that are associated with increased peri-operative risk. They further tend to present with more locally advanced disease, more likely to obstruct or have disseminated disease. The aim of this review was to investigate the feasibility of laparoscopic colorectal resection in very elderly patients, and whether there are benefits over open surgery for colorectal cancer. METHODS: A systematic literature search was performed on Medline, Pubmed, Embase and Google Scholar. All comparative studies evaluating patients undergoing laparoscopic versus open surgery for colorectal cancer in the patients population over 85 were included. The primary outcomes were 30-day mortality and 30-day overall morbidity. Secondary outcomes were operating time, time to oral diet, number of retrieved lymph nodes, blood loss and 5-year survival. RESULTS: The search provided 1507 citations. Sixty-nine articles were retrieved for full text analysis, and only six retrospective studies met the inclusion criteria. Overall mortality for elective laparoscopic resection was 2.92% and morbidity 23%. No single study showed a significant difference between laparoscopic and open surgery for morbidity or mortality, but pooled data analysis demonstrated reduced morbidity in the laparoscopic group (p = 0.032). Patients undergoing laparoscopic surgery are more likely to have a shorter hospital stay and a shorter time to oral diet. CONCLUSION: Elective laparoscopic resection for colorectal cancer in the over 85 age group is feasible and safe and offers similar advantages over open surgery to those demonstrated in patients of younger ages

A história e as ciências sociais na profissionalização da historiografia argentina

In this article the author reconstructs the relations between academic historians in Argentina and the new contributions made by the social sciences during a period spanning from the mid 19th century, with the publication of Historia de Belgrano (1857) by Bartolomé Mitre, to the end of the First World War, when the so-called New Historical School began to control the discipline in the university following the 1918 University Reform. To this end, the text pays special attention to the ways in which the local debate in Argentina appropriated the proposals of positivist European historiography, such as the work of H. Taine, concentrating on the following authors: Bartolomé Mitre, Vicente Fidel López, José María Ramos Mejía, Ernesto Quesada, Augustín García, Juan Álvarez and Paul Groussac.Neste artigo, o autor reconstrói as relações travadas entre os praticantes da disciplina histórica na Argentina e os novos aportes trazidos pelas ciências sociais, num período que vai desde meados do século XIX, com a Historia de Belgrano (1857), de Bartolomé Mitre, até o término da Primeira Guerra Mundial, quando a chamada Nueva Escuela Histórica passa a controlar a disciplina na universidade (após a Reforma Universitária de 1918). Para tal, detém-se especialmente nas apropriações feitas pelo debate local argentino das proposições da historiografia positivista europeia, como a obra de H. Taine, por exemplo, concentrando-se nos seguintes autores: Bartolomé Mitre, Vicente Fidel López, José María Ramos Mejía, Ernesto Quesada, Augustín García, Juan Álvarez e Paul Groussac

High energy photon-neutrino elastic scattering

The one-loop helicity amplitudes for the elastic scattering process $\gamma\nu\to\gamma\nu$ in the Standard Model are computed at high center of mass energies. A general decomposition of the amplitudes is utilized to investigate the validity of some of the key features of our results. In the center of mass, where $\sqrt{s} = 2\omega$, the cross section grows roughly as $\omega^6$ to near the threshold for $W$-boson production, $\sqrt{s} = m_W$. Although suppressed at low energies, we find that the elastic cross section exceeds the cross section for $\gamma\nu\to\gamma\gamma\nu$ when $\sqrt{s}>13$ GeV. We demonstrate that the scattered photons are circularly polarized and the net value of the polarization is non-zero. Astrophysical implications of high energy photon-neutrino scattering are discussed.Comment: 9 pages, 7 figures, RevTeX

Phenotype-specific association of the TGFBR3 locus with nonsyndromic cryptorchidism

PURPOSE: Based on a genome-wide association study of testicular dysgenesis syndrome showing a possible association with TGFBR3, we analyzed data from a larger, phenotypically restricted cryptorchidism population for potential replication of this signal. MATERIALS AND METHODS: We excluded samples based on strict quality control criteria, leaving 844 cases and 2,718 controls of European ancestry that were analyzed in 2 separate groups based on genotyping platform (ie Illumina® HumanHap550, version 1 or 3, or Human610-Quad, version 1 BeadChip in group 1 and Human OmniExpress 12, version 1 BeadChip platform in group 2). Analyses included genotype imputation at the TGFBR3 locus, association analysis of imputed data with correction for population substructure, subsequent meta-analysis of data for groups 1 and 2, and selective genotyping of independent cases (330) and controls (324) for replication. We also measured Tgfbr3 mRNA levels and performed TGFBR3/betaglycan immunostaining in rat fetal gubernaculum. RESULTS: We identified suggestive (p ≤ 1× 10(-4)) association of markers in/near TGFBR3, including rs9661103 (OR 1.40; 95% CI 1.20, 1.64; p = 2.71 × 10(-5)) and rs10782968 (OR 1.58; 95% CI 1.26, 1.98; p = 9.36 × 10(-5)) in groups 1 and 2, respectively. In subgroup analyses we observed strongest association of rs17576372 (OR 1.42; 95% CI 1.24, 1.60; p = 1.67 × 10(-4)) with proximal and rs11165059 (OR 1.32; 95% CI 1.15, 1.38; p = 9.42 × 10(-4)) with distal testis position, signals in strong linkage disequilibrium with rs9661103 and rs10782968, respectively. Association of the prior genome-wide association study signal (rs12082710) was marginal (OR 1.13; 95% CI 0.99, 1.28; p = 0.09 for group 1), and we were unable to replicate signals in our independent cohort. Tgfbr3/betaglycan was differentially expressed in wild-type and cryptorchid rat fetal gubernaculum. CONCLUSIONS: These data suggest complex or phenotype specific association of cryptorchidism with TGFBR3 and the gubernaculum as a potential target of TGFβ signaling

Two classes of bipartite networks: nested biological and social systems

Bipartite graphs have received some attention in the study of social networks and of biological mutualistic systems. A generalization of a previous model is presented, that evolves the topology of the graph in order to optimally account for a given Contact Preference Rule between the two guilds of the network. As a result, social and biological graphs are classified as belonging to two clearly different classes. Projected graphs, linking the agents of only one guild, are obtained from the original bipartite graph. The corresponding evolution of its statistical properties is also studied. An example of a biological mutualistic network is analyzed in great detail, and it is found that the model provides a very good quantitative fitting of its properties. The model also provides a proper qualitative description of the statistical features observed in social webs, suggesting the possible reasons underlying the difference in the organization of these two kinds of bipartite networks.Comment: 11 pages, 5 figure