Structural efficiency of percolation landscapes in flow networks

Complex networks characterized by global transport processes rely on the presence of directed paths from input to output nodes and edges, which organize in characteristic linked components. The analysis of such network-spanning structures in the framework of percolation theory, and in particular the key role of edge interfaces bridging the communication between core and periphery, allow us to shed light on the structural properties of real and theoretical flow networks, and to define criteria and quantities to characterize their efficiency at the interplay between structure and functionality. In particular, it is possible to assess that an optimal flow network should look like a "hairy ball", so to minimize bottleneck effects and the sensitivity to failures. Moreover, the thorough analysis of two real networks, the Internet customer-provider set of relationships at the autonomous system level and the nervous system of the worm Caenorhabditis elegans --that have been shaped by very different dynamics and in very different time-scales--, reveals that whereas biological evolution has selected a structure close to the optimal layout, market competition does not necessarily tend toward the most customer efficient architecture.Comment: 8 pages, 5 figure

Emergence of scale-free close-knit friendship structure in online social networks

Despite the structural properties of online social networks have attracted much attention, the properties of the close-knit friendship structures remain an important question. Here, we mainly focus on how these mesoscale structures are affected by the local and global structural properties. Analyzing the data of four large-scale online social networks reveals several common structural properties. It is found that not only the local structures given by the indegree, outdegree, and reciprocal degree distributions follow a similar scaling behavior, the mesoscale structures represented by the distributions of close-knit friendship structures also exhibit a similar scaling law. The degree correlation is very weak over a wide range of the degrees. We propose a simple directed network model that captures the observed properties. The model incorporates two mechanisms: reciprocation and preferential attachment. Through rate equation analysis of our model, the local-scale and mesoscale structural properties are derived. In the local-scale, the same scaling behavior of indegree and outdegree distributions stems from indegree and outdegree of nodes both growing as the same function of the introduction time, and the reciprocal degree distribution also shows the same power-law due to the linear relationship between the reciprocal degree and in/outdegree of nodes. In the mesoscale, the distributions of four closed triples representing close-knit friendship structures are found to exhibit identical power-laws, a behavior attributed to the negligible degree correlations. Intriguingly, all the power-law exponents of the distributions in the local-scale and mesoscale depend only on one global parameter -- the mean in/outdegree, while both the mean in/outdegree and the reciprocity together determine the ratio of the reciprocal degree of a node to its in/outdegree.Comment: 48 pages, 34 figure

In vitro susceptibility to pyrimethamine of DHFR I164L single mutant Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>Recently, <it>Plasmodium falciparum </it>parasites bearing <it>Pfdhfr </it>I164L single mutation were found in Madagascar. These new mutants may challenge the use of antifolates for the intermittent preventive treatment of malaria during pregnancy (IPTp). Assays with transgenic bacteria suggested that I164L parasites have a wild-type phenotype for pyrimethamine but it had to be confirmed by testing the parasites themselves.</p> <p>Methods</p> <p>Thirty <it>Plasmodium falciparum </it>clinical isolates were collected in 2008 in the south-east of Madagascar. A part of <it>Pfdhfr </it>gene encompassing codons 6 to 206 was amplified by PCR and the determination of the presence of single nucleotide polymorphisms was performed by DNA sequencing. The multiplicity of infection was estimated by using an allelic family-specific nested PCR. Isolates that appeared monoclonal were submitted to culture adaptation. Determination of IC_50sto pyrimethamine was performed on adapted isolates.</p> <p>Results</p> <p>Four different <it>Pfdhfr </it>alleles were found: the 164L single mutant-type (N = 13), the wild-type (N = 7), the triple mutant-type 51I/59R/108N (N = 9) and the double mutant-type 108N/164L (N = 1). Eleven out 30 (36.7%) of <it>P. falciparum </it>isolates were considered as monoclonal infection. Among them, five isolates were successfully adapted in culture and tested for pyrimethamine <it>in vitro </it>susceptibility. The wild-type allele was the most susceptible with a 50% inhibitory concentration (IC₅₀) < 10 nM. The geometric mean of IC₅₀of the three I164L mutant isolates was 6-fold higher than the wild-type with 61.3 nM (SD = 3.2 nM, CI95%: 53.9-69.7 nM). These values remained largely below the IC₅₀of the triple mutant parasite (13,804 nM).</p> <p>Conclusion</p> <p>The IC₅₀s of the I164L mutant isolates were significantly higher than those of the wild-type (6-fold higher) and close from those usually reported for simple mutants S108N (roughly10-fold higher than wild type). Given the observed values, the determination of IC₅₀s directly on parasites did not confirm what has been found on transgenic bacteria. The prevalence increase of the <it>Pfdhfr </it>I164L single mutant parasite since 2006 could be explained by the selective advantage of this allele under sulphadoxine-pyrimethamine pressure. The emergence of highly resistant alleles should be considered in the future, in particular because an unexpected double mutant-type allele S108N/I164L has been already detected.</p

Brief Report: Question-Asking and Collateral Language Acquisition in Children with Autism

The literature suggests children with autism use communication primarily for requests and protests, and almost never for information-seeking. This study investigated whether teaching “Where” questions using intrinsic reinforcement procedures would produce the generalized use of the question, and whether concomitant improvements in related language structures, provided as answers to the children’s questions, would occur. In the context of a multiple baseline across participants design, data showed that the children could rapidly acquire and generalize the query, and that there were collateral improvements in the children’s use of language structures corresponding to the answers to the questions the children asked. The results are discussed in the context of teaching child initiations to improve linguistic competence in children with autism

Cross validation of bi-modal health-related stress assessment

This study explores the feasibility of objective and ubiquitous stress assessment. 25 post-traumatic stress disorder patients participated in a controlled storytelling (ST) study and an ecologically valid reliving (RL) study. The two studies were meant to represent an early and a late therapy session, and each consisted of a "happy" and a "stress triggering" part. Two instruments were chosen to assess the stress level of the patients at various point in time during therapy: (i) speech, used as an objective and ubiquitous stress indicator and (ii) the subjective unit of distress (SUD), a clinically validated Likert scale. In total, 13 statistical parameters were derived from each of five speech features: amplitude, zero-crossings, power, high-frequency power, and pitch. To model the emotional state of the patients, 28 parameters were selected from this set by means of a linear regression model and, subsequently, compressed into 11 principal components. The SUD and speech model were cross-validated, using 3 machine learning algorithms. Between 90% (2 SUD levels) and 39% (10 SUD levels) correct classification was achieved. The two sessions could be discriminated in 89% (for ST) and 77% (for RL) of the cases. This report fills a gap between laboratory and clinical studies, and its results emphasize the usefulness of Computer Aided Diagnostics (CAD) for mental health care

Negative parental responses to coming out and family functioning in a sample of lesbian and gay young adults

Parental responses to youths' coming out (CO) are crucial to the subsequent adjustment of children and family. The present study investigated the negative parental reaction to the disclosure of same-sex attraction and the differences between maternal and paternal responses, as reported by their homosexual daughters and sons. Participants' perceptions of their parents' reactions (evaluated through the Perceived Parental Reactions Scale, PPRS), age at coming out, gender, parental political orientation, and religiosity involvement, the family functioning (assessed through the Family Adaptability and Cohesion Evaluation Scales, FACES IV), were assessed in 164 Italian gay and lesbian young adults. Pearson correlation coefficients were calculated to assess the relation between family functioning and parental reaction to CO. The paired sample t-test was used to compare mothers and fathers' scores on the PPRS. Hierarchical multiple regression was conducted to analyze the relevance of each variable. No differences were found between mothers and fathers in their reaction to the disclosure. The analysis showed that a negative reaction to coming out was predicted by parents' right-wing political conservatism, strong religious beliefs, and higher scores in the scales Rigid and Enmeshed. Findings confirm that a negative parental reaction is the result of poor family resources to face a stressful situation and a strong belief in traditional values. These results have important implications in both clinical and social fields

Published and not fully published double-blind, randomised, controlled trials with oral naratriptan in the treatment of migraine: a review based on the GSK Trial Register

Naratriptan 2.5 mg is now an over-the-counter drug in Germany. This should increase the interest in drug. The GSK Trial Register was searched for published and unpublished double-blind, randomised, controlled trials (RCTs) concerning the use of naratriptan in migraine. Only 7 of 17 RCTs are published in full. Naratriptan 2.5 mg is superior to placebo for acute migraine treatment in 6 RCTs, but inferior to sumatriptan 100 mg and rizatriptan 10 mg in one RCT each. This dose of naratriptan has no more adverse events than placebo. Naratriptan 1 mg b.i.d. has some effect in the short-term prophylactic treatment of menstruation-associated migraine in 3 RCTs. In 2 RCTs, naratriptan 2.5 mg was equivalent to naproxen sodium 375 mg for migraine-related quality of life. Naratriptan 2.5 mg (34% preference) was superior to naproxen sodium 500 mg (25% preference). Naratriptan 2.5 mg is better than placebo in the acute treatment of migraine. The adverse effect profile of naratriptan 2.5 mg is similar to that of placebo. The efficacy of naratriptan 2.5 mg versus NSAIDs is not sufficiently investigated. Naratriptan, when available OTC is a reasonable second or third choice on the step care ladder in the acute treatment of migraine

Experiences of parenting and clinical intervention for mothers affected by personality disorder: a pilot qualitative study combining parent and clinician perspectives

Background: Evidence-based parenting programmes are recommended for the treatment of child mental health difficulties. Families with complex psychosocial needs show poorer retention and outcomes when participating in standard parenting programmes. The Helping Families Programme (HFP) is a 16-week community-based parenting intervention designed to meet the needs of these families, including families with parental personality disorder. This study aimed to explore the help seeking and participatory experiences of parents with a diagnosis of personality disorder. It further aimed to examine the acceptability of referral and intervention processes for the HFP from the perspectives of (i) clinicians referring into the programme; and (ii) referred parents. Method: Semi-structured interviews were conducted with parents recruited to receive HFP (n = 5) as part of a research case series and the referring NHS child and adolescent mental health service (CAMHS) clinicians (n = 5). Transcripts were analysed using Interpretive Phenomenological Analysis. Results: Four themes were identified for parents: (i) the experience of parenthood, (ii) being a parent affected by personality disorder, (iii) experience of the intervention, and (iv) qualities of helping. Three themes emerged for clinicians: (i) challenges of addressing parental need, (ii) experience of engaging parents with personality disorders and (iii) limited involvement during HFP. Comparison of parent and clinician themes led to the identification of two key interlinked themes: (i) concerns prior to receiving the intervention, and (ii) the challenges of working together without a mutual understanding. Conclusions: This pilot study identifies potentially significant challenges of working with parents affected by personality disorder and engaging them in HFP and other similar interventions. Results have important wider clinical implications by highlighting potential barriers to engagement and participation and providing insights on how these barriers might be overcome. Findings have been used to inform the referral and intervention processes of a pilot RCT and further intervention development