Cycle-centrality in complex networks

Networks are versatile representations of the interactions between entities in complex systems. Cycles on such networks represent feedback processes which play a central role in system dynamics. In this work, we introduce a measure of the importance of any individual cycle, as the fraction of the total information flow of the network passing through the cycle. This measure is computationally cheap, numerically well-conditioned, induces a centrality measure on arbitrary subgraphs and reduces to the eigenvector centrality on vertices. We demonstrate that this measure accurately reflects the impact of events on strategic ensembles of economic sectors, notably in the US economy. As a second example, we show that in the protein-interaction network of the plant Arabidopsis thaliana, a model based on cycle-centrality better accounts for pathogen activity than the state-of-art one. This translates into pathogen-targeted-proteins being concentrated in a small number of triads with high cycle-centrality. Algorithms for computing the centrality of cycles and subgraphs are available for download

The TASS-Q: The Team-referent Availability of Social Support Questionnaire

Objectives To provide initial evidence for the construct validity of the Team-referent Availability of Social Support Questionnaire (the TASS-Q). Design Cross-sectional in Study 1, and two time points in Study 2. Method The preliminary study required participants (N = 47) to assess the content validity—dimensional belonging, understanding, and relevance—of the TASS-Q items. In Study 1, participants (n = 336) completed the TASS-Q and measures of social desirability and negative affectivity. In Study 2, approximately one week before a competition (Day 1, Time 1) participants (n = 413) completed the TASS-Q; approximately 1 h before the same competition (Day 7–9, Time 2) participants completed measures of collective efficacy in relation to the impending competition and team cohesion. Results Following evidence for the scale content validity of the TASS-Q in the preliminary study, Study 1 provided support for the factor structure of the TASS-Q comprising emotional, esteem, informational, and tangible dimensions. Study 2 provided partial evidence for the factor structure of the TASS-Q and evidence of the criterion-related validity of the measure, demonstrating that (a) team-referent esteem support was a positive predictor of collective efficacy, (b) support dimensions, collectively, explained significant variance in task cohesion dimensions, and (c) emotional support was a positive predictor of social cohesion (group integration—social). Conclusions The article provides initial evidence for the construct validity of the TASS-Q and demonstrates, for team-referent social support, the theoretical advantages of examining a multidimensional conceptualisation of perceived availability of social support

Weatherability and Leach Resistance of Wood Impregnated with Nano-Zinc Oxide

Southern pine specimens vacuum-treated with nano-zinc oxide (nano-ZnO) dispersions were evaluated for leach resistance and UV protection. Virtually, no leaching occurred in any of the nano-ZnO–treated specimens in a laboratory leach test, even at the highest retention of 13 kg/m3. However, specimens treated with high concentrations of nano-ZnO showed 58–65% chemical depletion after 12 months of outdoor exposure. Protection from UV damage after 12 months exposure is visibly obvious on both exposed and unexposed surfaces compared to untreated controls. Graying was markedly diminished, although checking occurred in all specimens. Nano-zinc oxide treatment at a concentration of 2.5% or greater provided substantial resistance to water absorption following 12 months of outdoor exposure compared to untreated and unweathered southern pine. We conclude that nano-zinc oxide can be utilized in new wood preservative formulations to impart resistance to leaching, water absorption and UV damage of wood

Scintigraphic assessment of bone status at one year following hip resurfacing : comparison of two surgical approaches using SPECT-CT scan

Objectives: To study the vascularity and bone metabolism of the femoral head/neck following hip resurfacing arthroplasty, and to use these results to compare the posterior and the trochanteric-flip approaches. Methods: In our previous work, we reported changes to intra-operative blood flow during hip resurfacing arthroplasty comparing two surgical approaches. In this study, we report the vascularity and the metabolic bone function in the proximal femur in these same patients at one year after the surgery. Vascularity and bone function was assessed using scintigraphic techniques. Of the 13 patients who agreed to take part, eight had their arthroplasty through a posterior approach and five through a trochanteric-flip approach. Results: One year after surgery, we found no difference in the vascularity (vascular phase) and metabolic bone function (delayed phase) at the junction of the femoral head/neck between the two groups of patients. Higher radiopharmaceutical uptake was found in the region of the greater trochanter in the trochanteric-flip group, related to the healing osteotomy. Conclusions: Our findings using scintigraphic techniques suggest that the greater intra-operative reduction in blood flow to the junction of the femoral head/neck, which is seen with the posterior approach compared with trochanteric flip, does not result in any difference in vascularity or metabolic bone function one year after surgery

Segregation discovery in a social network of companies

We introduce a framework for a data-driven analysis of segregation of minority groups in social networks, and challenge it on a complex scenario. The framework builds on quantitative measures of segregation, called segregation indexes, proposed in the social science literature. The segregation discovery problem consists of searching sub-graphs and sub-groups for which a reference segregation index is above a minimum threshold. A search algorithm is devised that solves the segregation problem. The framework is challenged on the analysis of segregation of social groups in the boards of directors of the real and large network of Italian companies connected through shared directors

Electronic structure and volume effect on thermoelectric transport in p-type Bi and Sb tellurides

Thermoelectric transport properties (Seebeck coefficient, S, and electrical conductivity, sigma) of p-type Bi and Sb tellurides are investigated using a first-principles all-electron density-functional approach. We demonstrate that the carrier concentration, band gap, and lattice constants have an important influence on the temperature behavior of S and that the volume expansion by 5.5% in Sb(2)Te(3) results in an increase in S by 33 mu V/K at 300 K. We argue that in addition to the electronic structure characteristics, the volume also affects the value of S and hence should be considered as an origin of the experimental observations that S can be enhanced by doping Sb(2)Te(3) with Bi (which has a larger ionic size) in Sb sites or by the deposition of thick Bi(2)Te(3) layers alternating with thinner Sb(2)Te(3) layers in a superlattice, Bi(2)Te(3)/Sb(2)Te(3). We show that the optimal carrier concentration for the best power factor of Bi(2)Te(3) and Sb(2)Te(3) is approximately 10(19) cm(-3).open114343sciescopu

The interplay of microscopic and mesoscopic structure in complex networks

Not all nodes in a network are created equal. Differences and similarities exist at both individual node and group levels. Disentangling single node from group properties is crucial for network modeling and structural inference. Based on unbiased generative probabilistic exponential random graph models and employing distributive message passing techniques, we present an efficient algorithm that allows one to separate the contributions of individual nodes and groups of nodes to the network structure. This leads to improved detection accuracy of latent class structure in real world data sets compared to models that focus on group structure alone. Furthermore, the inclusion of hitherto neglected group specific effects in models used to assess the statistical significance of small subgraph (motif) distributions in networks may be sufficient to explain most of the observed statistics. We show the predictive power of such generative models in forecasting putative gene-disease associations in the Online Mendelian Inheritance in Man (OMIM) database. The approach is suitable for both directed and undirected uni-partite as well as for bipartite networks

Infant feeding bottle design, growth and behaviour: results from a randomised trial

BACKGROUND: Whether the design of an anti-vacuum infant feeding bottle influences infant milk intake, growth or behavior is unknown, and was the subject of this randomized trial. METHODS: SUBJECTS: 63 (36 male) healthy, exclusively formula-fed term infants. INTERVENTION: Randomisation to use Bottle A (n = 31), one-way air valve: Philips Avent) versus Bottle B (n = 32), internal venting system: Dr Browns). 74 breast-fed reference infants were recruited, with randomisation (n = 24) to bottle A (n = 11) or B (n = 13) if bottle-feeding was subsequently introduced. Randomisation: stratified by gender and parity; computer-based telephone randomisation by independent clinical trials unit. SETTING: Infant home. PRIMARY OUTCOME MEASURE: infant weight gain to 4 weeks. SECONDARY OUTCOMES: (i) milk intake (ii) infant behaviour measured at 2 weeks (validated 3-day diary); (iii) risk of infection; (iv) continuation of breastfeeding following introduction of mixed feeding. RESULTS: Number analysed for primary outcome: Bottle A n = 29, Bottle B n = 25. PRIMARY OUTCOME: There was no significant difference in weight gain between randomised groups (0-4 weeks Bottle A 0.74 (SD 1.2) SDS versus bottle B 0.51 (0.39), mean difference 0.23 (95% CI -0.31 to 0.77). SECONDARY OUTCOMES: Infants using bottle A had significantly less reported fussing (mean 46 versus 74 minutes/day, p < 0.05) than those using bottle B. There was no significant difference in any other outcome measure. Breast-fed reference group: There were no significant differences in primary or secondary outcomes between breast-fed and formula fed infants. The likelyhood of breastfeeding at 3 months was not significantly different in infants subsequently randomised to bottle A or B. CONCLUSION: Bottle design may have short-term effects on infant behaviour which merit further investigation. No significant effects were seen on milk intake or growth; confidence in these findings is limited by the small sample size and this needs confirmation in a larger study. TRIAL REGISTRATION: Clinical Trials.gov NCT00325208

Management of patients with biliary sphincter of Oddi disorder without sphincter of Oddi manometry

<p>Abstract</p> <p>Background</p> <p>The paucity of controlled data for the treatment of most biliary sphincter of Oddi disorder (SOD) types and the incomplete response to therapy seen in clinical practice and several trials has generated controversy as to the best course of management of these patients. In this observational study we aimed to assess the outcome of patients with biliary SOD managed without sphincter of Oddi manometry.</p> <p>Methods</p> <p>Fifty-nine patients with biliary SOD (14% type I, 51% type II, 35% type III) were prospectively enrolled. All patients with a dilated common bile duct were offered endoscopic retrograde cholangiopancreatography (ERCP) and sphincterotomy whereas all others were offered medical treatment alone. Patients were followed up for a median of 15 months and were assessed clinically for response to treatment.</p> <p>Results</p> <p>At follow-up 15.3% of patients reported complete symptom resolution, 59.3% improvement, 22% unchanged symptoms, and 3.4% deterioration. Fifty-one percent experienced symptom resolution/improvement on medical treatment only, 12% after sphincterotomy, and 10% after both medical treatment/sphincterotomy. Twenty percent experienced at least one recurrence of symptoms after initial response to medical and/or endoscopic treatment. Fifty ERCP procedures were performed in 24 patients with an 18% complication rate (16% post-ERCP pancreatitis). The majority of complications occurred in the first ERCP these patients had. Most complications were mild and treated conservatively. Age, gender, comorbidity, SOD type, dilated common bile duct, presence of intact gallbladder, or opiate use were not related to the effect of treatment at the end of follow-up (p > 0.05 for all).</p> <p>Conclusions</p> <p>Patients with biliary SOD may be managed with a combination of endoscopic sphincterotomy (performed in those with dilated common bile duct) and medical therapy without manometry. The results of this approach with regards to symptomatic relief and ERCP complication rate are comparable to those previously published in the literature in cohorts of patients assessed by manometry.</p