Resilience or robustness : identifying topological vulnerabilities in rail networks

Many critical infrastructure systems have network structure and are under stress. Despite their national importance, the complexity of large-scale transport networks means we do not fully understand their vulnerabilities to cascade failures. The research in this paper examines the interdependent rail networks in Greater London and surrounding commuter area. We focus on the morning commuter hours, where the system is under the most demand stress. There is increasing evidence that the topological shape of the network plays an important role in dynamic cascades. Here, we examine whether the different topological measures of resilience (stability) or robustness (failure) are more appropriate for understanding poor railway performance. The results show that resilience and not robustness has a strong correlation to the consumer experience statistics. Our results are a way of describing the complexity of cascade dynamics on networks without the involvement of detailed agent-based-models, showing that cascade effects are more responsible for poor performance than failures. The network science analysis hints at pathways towards making the network structure more resilient by reducing feedback loops

Measuring implicit bi-dimensional attitudes and predicting speeding behaviour

Attitudes are bi-dimensional predictors of behaviour, meaning that attitudes comprise separate positive and negative dimensions, which both predict behaviour independently (Elliott et al., 2015). Furthermore, the positive dimension of attitude is the stronger predictor for risky behaviours (e.g., speeding). This implies that evaluative beliefs about positive behavioural consequences strongly influence subsequent behavioural performance. Beliefs about negative behavioural consequences do not. In previous research, bi-dimensional attitudes have been measured using questionnaires, which tap explicit cognitive judgements. However, implicit cognitive processes are likely to dictate the performance of habitual behaviours such as speeding. We therefore measured bi-dimensional attitudes using an implicit association test (IAT). The presentation will cover the development of the IAT and the results from regression modelling, in which test performance was used to predict speeding behaviour. The implications for better understanding the cognitive processes that dictate behavioural performance and how to change behaviour will be discussed

Global diversity in the TAS2R38 bitter taste receptor: Revisiting a classic evolutionary PROPosal

The ability to taste phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) is a polymorphic trait mediated by the TAS2R38 bitter taste receptor gene. It has long been hypothesized that global genetic diversity at this locus evolved under pervasive pressures from balancing natural selection. However, recent high-resolution population genetic studies of TAS2Rs suggest that demographic events have played a critical role in the evolution of these genes. We here utilized the largest TAS2R38 database yet analyzed, consisting of 5,589 individuals from 105 populations, to examine natural selection, haplotype frequencies and linkage disequilibrium to estimate the effects of both selection and demography on contemporary patterns of variation at this locus. We found signs of an ancient balancing selection acting on this gene but no post Out-Of-Africa departures from neutrality, implying that the current observed patterns of variation can be predominantly explained by demographic, rather than selective events. In addition, we found signatures of ancient selective forces acting on different African TAS2R38 haplotypes. Collectively our results provide evidence for a relaxation of recent selective forces acting on this gene and a revised hypothesis for the origins of the present-day worldwide distribution of TAS2R38 haplotypes

Swift Observations of GRB 050603: An afterglow with a steep late time decay slope

We report the results of Swift observations of the Gamma Ray Burst GRB 050603. With a V magnitude V=18.2 about 10 hours after the burst the optical afterglow was the brightest so far detected by Swift and one of the brightest optical afterglows ever seen. The Burst Alert Telescope (BAT) light curves show three fast-rise-exponential-decay spikes with $T_{90}$=12s and a fluence of 7.6$\times 10^{-6}$ ergs cm$^{-2}$ in the 15-150 keV band. With an $E_{\rm \gamma, iso} = 1.26 \times 10^{54}$ ergs it was also one of the most energetic bursts of all times. The Swift spacecraft began observing of the afterglow with the narrow-field instruments about 10 hours after the detection of the burst. The burst was bright enough to be detected by the Swift UV/Optical telescope (UVOT) for almost 3 days and by the X-ray Telescope (XRT) for a week after the burst. The X-ray light curve shows a rapidly fading afterglow with a decay index $\alpha$=1.76$^{+0.15}_{-0.07}$. The X-ray energy spectral index was $\beta_{\rm X}$=0.71\plm0.10 with the column density in agreement with the Galactic value. The spectral analysis does not show an obvious change in the X-ray spectral slope over time. The optical UVOT light curve decays with a slope of $\alpha$=1.8\plm0.2. The steepness and the similarity of the optical and X-ray decay rates suggest that the afterglow was observed after the jet break. We estimate a jet opening angle of about 1-2$^{\circ}$Comment: 14 pages, accepted for publication in Ap

GRB 060313: A New Paradigm for Short-Hard Bursts?

We report the simultaneous observations of the prompt emission in the gamma-ray and hard X-ray bands by the Swift-BAT and the KONUS-Wind instruments of the short-hard burst, GRB 060313. The observations reveal multiple peaks in both the gamma-ray and hard X-ray bands suggesting a highly variable outflow from the central explosion. We also describe the early-time observations of the X-ray and UV/Optical afterglows by the Swift XRT and UVOT instruments. The combination of the X-ray and UV/Optical observations provide the most comprehensive lightcurves to date of a short-hard burst at such an early epoch. The afterglows exhibit complex structure with different decay indices and flaring. This behavior can be explained by the combination of a structured jet, radiative loss of energy, and decreasing microphysics parameters occurring in a circum-burst medium with densities varying by a factor of approximately two on a length scale of 10^17 cm. These density variations are normally associated with the environment of a massive star and inhomogeneities in its windy medium. However, the mean density of the observed medium (n approximately 10^−4 cm^3) is much less than that expected for a massive star. Although the collapse of a massive star as the origin of GRB 060313 is unlikely, the merger of a compact binary also poses problems for explaining the behavior of this burst. Two possible suggestions for explaining this scenario are: some short bursts may arise from a mechanism that does not invoke the conventional compact binary model, or soft late-time central engine activity is producing UV/optical but no X-ray flaring.Comment: 28 pages, 6 figures. Accepted for publication in ApJ. Clarifications made and typos correcte

Measuring explicit and implicit bi-dimensional attitudes to predict studying behaviour and outcome

Attitudes have traditionally been measured as unitary constructs i.e. a person has a positive or a negative evaluation of a concept. However, Elliott et al., (2015) suggests that attitudes are better measured as having concurrent positive and negative dimensions which act as independent predictors of behaviour. In addition to these explicit measures of attitude, implicit measures also have been shown to be predictive of behaviour (see Greenwald & Banaji, 1995) but the relationship between bi-dimensional explicit and implicit measures has never been examined. This study measures bi-dimensional explicit attitudes via questionnaire and implicit bi-directional attitudes via a specially constructed Implicit Association Test and regression modelling examines the relationship between these, studying behaviour and exam performance in Higher Education students. Theoretical conclusions from these results and implications for real world behaviour change will be discussed

NGF-TrkA signaling dictates neural ingrowth and aberrant osteochondral differentiation after soft tissue trauma

: Pain is a central feature of soft tissue trauma, which under certain contexts, results in aberrant osteochondral differentiation of tissue-specific stem cells. Here, the role of sensory nerve fibers in this abnormal cell fate decision is investigated using a severe extremity injury model in mice. Soft tissue trauma results in NGF (Nerve growth factor) expression, particularly within perivascular cell types. Consequently, NGF-responsive axonal invasion occurs which precedes osteocartilaginous differentiation. Surgical denervation impedes axonal ingrowth, with significant delays in cartilage and bone formation. Likewise, either deletion of Ngf or two complementary methods to inhibit its receptor TrkA (Tropomyosin receptor kinase A) lead to similar delays in axonal invasion and osteochondral differentiation. Mechanistically, single-cell sequencing suggests a shift from TGFβ to FGF signaling activation among pre-chondrogenic cells after denervation. Finally, analysis of human pathologic specimens and databases confirms the relevance of NGF-TrkA signaling in human disease. In sum, NGF-mediated TrkA-expressing axonal ingrowth drives abnormal osteochondral differentiation after soft tissue trauma. NGF-TrkA signaling inhibition may have dual therapeutic use in soft tissue trauma, both as an analgesic and negative regulator of aberrant stem cell differentiation

Modelagem do crescimento da aprendizagem nos anos iniciais com dados longitudinais da pesquisa GERES

Este artigo compara duas abordagens de valor agregado para dados oriundos do survey educacional de recorte longitudinal, chamado GERES - Estudo Longitudinal da Geração Escolar 2005, que acompanhou uma coorte de alunos de mais de 300 escolas públicas e privadas ao longo dos primeiros quatro anos do Ensino Fundamental. Ambas as abordagens utilizam modelos lineares hierárquicos, permitindo o agrupamento natural dos dados educacionais provenientes dos três níveis: aluno, turma e escola. Na primeira abordagem de valor agregado, constroem-se modelos cuja variável dependente é a proficiência do aluno em cada ano avaliado. Com um modelo distinto para cada ano é possível detectar fatores do aluno, da turma e da escola associados ao desempenho dos alunos. A segunda abordagem cria modelos para mostrar o efeito das covariáveis de aluno, turma e escola nas curvas de evolução da proficiência ao longo do período do estudo. Quando comparados os dois tipos de modelos de valor agregado, o primeiro foi o mais eficiente em diagnosticar os efeitos do ambiente e da prática pedagógica do professor, mas somente em determinados anos. Já o segundo tipo de modelo foi capaz de identificar curvas de evolução de proficiência de formatos distintos de acordo com determinadas características das escolas e dos alunos, mas foi menos sensível na identificação de variáveis associadas ao processo de formação de grupos e à prática pedagógica do professor. Os dois tipos de modelos de valor agregado oferecem indicações de processos de aprendizagem diferenciados para as disciplinas Língua Portuguesa e Matemática que mereceriam estudos adicionais

The African Genome Variation Project shapes medical genetics in Africa.

Given the importance of Africa to studies of human origins and disease susceptibility, detailed characterization of African genetic diversity is needed. The African Genome Variation Project provides a resource with which to design, implement and interpret genomic studies in sub-Saharan Africa and worldwide. The African Genome Variation Project represents dense genotypes from 1,481 individuals and whole-genome sequences from 320 individuals across sub-Saharan Africa. Using this resource, we find novel evidence of complex, regionally distinct hunter-gatherer and Eurasian admixture across sub-Saharan Africa. We identify new loci under selection, including loci related to malaria susceptibility and hypertension. We show that modern imputation panels (sets of reference genotypes from which unobserved or missing genotypes in study sets can be inferred) can identify association signals at highly differentiated loci across populations in sub-Saharan Africa. Using whole-genome sequencing, we demonstrate further improvements in imputation accuracy, strengthening the case for large-scale sequencing efforts of diverse African haplotypes. Finally, we present an efficient genotype array design capturing common genetic variation in Africa