Runaway massive stars as variable gamma-ray sources

Runaway stars are ejected from their formation sites well within molecular cores in giant dark clouds. Eventually, these stars can travel through the molecular clouds, which are highly inhomogeneous. The powerful winds of massive runaway stars interact with the medium forming bowshocks. Recent observations and theoretical modelling suggest that these bowshocks emit non-thermal radiation. As the massive stars move through the inhomogeneous ambient gas the physical properties of the bowshocks are modified, producing changes in the non-thermal emission. We aim to compute the non-thermal radiation produced in the bowshocks of runaway massive stars when travelling through a molecular cloud. We calculate the non-thermal emission and absorption for two types of massive runaway stars, an O9I and an O4I, as they move through a density gradient. We present the spectral energy distributions for the runaway stars modelled. Additionally, we obtain light curves at different energy ranges. We find significant variations in the emission over timescales of $\sim$ 1 yr. We conclude that bowshocks of massive runaway stars, under some assumptions, might be variable gamma-ray sources, with variability timescales that depend on the medium density profile. These objects might constitute a population of galactic gamma-ray sources turning on and off within years.Comment: 10 pages, 13 figures, accepted for publication in Astronomy & Astrophysic

A mechanism for fast radio bursts

Fast radio bursts are mysterious transient sources likely located at cosmological distances. The derived brightness temperatures exceed by many orders of magnitude the self-absorption limit of incoherent synchrotron radiation, implying the operation of a coherent emission process. We propose a radiation mechanism for fast radio bursts where the emission arises from collisionless Bremsstrahlung in strong plasma turbulence excited by relativistic electron beams. We discuss possible astrophysical scenarios in which this process might operate. The emitting region is a turbulent plasma hit by a relativistic jet, where Langmuir plasma waves produce a concentration of intense electrostatic soliton-like regions (cavitons). The resulting radiation is coherent and, under some physical conditions, can be polarised and have a power-law distribution in energy. We obtain radio luminosities in agreement with the inferred values for fast radio bursts. The timescale of the radio flare in some cases can be extremely fast, of the order of $10^{-3}$ s. The mechanism we present here can explain the main features of fast radio bursts and is plausible in different astrophysical sources, such as gamma-ray bursts and some Active Galactic Nuclei.Comment: 6 pages, 1 figure. Accepted for publication in Phys. Rev.

Towards Evidence Based M-Health Application Design in Cancer Patient Healthy Lifestyle Interventions

Cancer is one of the most prevalent diseases in Europe and the world. Significant correlations between dietary habits and cancer incidence and mortality have been confirmed by the literature. Physical activity habits are also directly implicated in the incidence of cancer. Lifestyle behaviour change may be benefited by using mobile technology to deliver health behaviour interventions. M-Health offers a promising cost-efficient approach to deliver en-masse interventions. Smartphone apps with constructs such as gamification and personalized have shown potential for helping individuals lose weight and maintain healthy lifestyle habits. However, evidence-based content and theory-based strategies have not been incorporated by those apps systematically yet. The aim of the current work is to put the foundations for a methodologically rigorous exploration of wellness/health intervention literature/app landscape towards detailed design specifications for connected health m-apps. In this context, both the overall work plan is described as well as the details for the significant steps of application space and literature space review. Both strategies for research and initial outcomes of it are presented. The expected evidence based design process for patient centered health and wellness interventions is going to be the primary input in the implementation process of upcoming patient centered health/wellness m-health interventions.ENJECT COST-STSM-ECOST-STSM-TD1405-220216-07045

Modelling the gas kinematics of an atypical Lyman-alpha emitting compact dwarf galaxy

Star-forming Compact Dwarf Galaxies (CDGs) resemble the expected pristine conditions of the first galaxies in the Universe and are the best systems to test models on primordial galaxy formation and evolution. Here we report on one of such CDGs, Tololo 1214-277, which presents a broad, single peaked, highly symmetric Ly$\alpha$ emission line that had evaded theoretical interpretation so far. In this paper we reproduce for the first time these line features with two different physically motivated kinematic models: an interstellar medium composed by outflowing clumps with random motions and an homogeneous gaseous sphere undergoing solid body rotation. The multiphase model requires a clump velocity dispersion of $54.3\pm 0.6$ km s$^{-1}$ with outflows of $54.3\pm 5.1$ km s$^{-1}$, while the bulk rotation velocity is constrained to be $348^{+75}_{-48}$ km s$^{-1}$. We argue that the results from the multiphase model provide a correct interpretation of the data. In that case the clump velocity dispersion implies a dynamical mass of $2\times 10^{9}$ M$_{\odot}$, ten times its baryonic mass. If future kinematic maps of Tololo 1214-277 confirm the velocities suggested by the multiphase model, it would provide additional support to expect such kinematic state in primordial galaxies, opening the opportunity to use the models and methods presented in this paper to constrain the physics of star formation and feedback in the early generation of Ly-$\alpha$ emitting galaxies.Comment: 10 pages, 5 figures, 2 tables. Accepted for publication in MNRA

Runaway stars as cosmic ray injectors inside molecular clouds

Giant molecular clouds (GMCs) are a new population of gamma-ray sources, being the target of cosmic rays (CRs) -- locally accelerated or not --. These clouds host very young stellar clusters where massive star formation takes place. Eventually, some of the stars are ejected from the clusters, becoming runaway stars. These stars move supersonically through the cloud and develop bowshocks where particles can be accelerated up to relativistic energies. As a result, the bowshocks present non-thermal emission, and inject relativistic protons in the cloud. These protons diffuse in the GMC interacting with the matter. We present a model for the non-thermal radiation generated by protons and secondary pairs accelerated in the bowshocks of massive runaways stars within young GMCs. We solve the transport equation for primary protons and secondary pairs as the stars move through the cloud. We present non-thermal emissivity maps in radio and in gamma rays as a function of time. We obtain X-ray luminosities of the order $\sim$ ${ 10^{32}}$ erg~s$^{-1}$ and gamma-ray luminosities $\sim$ $10^{34}$ erg~s$^{-1}$. We conclude that, under some assumptions, relativistic protons from massive runaway stars interacting with matter in GMCs give rise to extended non-thermal sources.Comment: 16 pages, 10 figures, accepted for publication in MNRA

The perceived role of bullying bystanders in Mexican secondary school settings

Bystanders play an important role in school bullying dynamics, having the power to provide or withhold the social rewards bullies seek. Bystander support is also beneficial for bullying victims, who experience less social and mental health problems if they have defenders. Even though bystanders generally disapprove of bullying, they rarely intervene in bullying incidents. Research suggests that two factors closely related to bystander intervention in bullying are moral disengagement and self-efficacy. Cultural influences and gender may also play a part in bullying and bystander dynamics. The main aim of this study was to explore Mexican secondary school students’ perceptions of their role in bullying situations. The study focused on gender differences in these perceptions, students' levels of self-efficacy, students’ use of moral disengagement dynamics, and student receptivity to material that encourages prosocial bystander behaviour. A questionnaire was developed to gauge students’ views on these topics, and administered to a sample of 186 secondary school students. Focus groups were also conducted to gain insight on group understandings and norms. A six-session workshop was designed and implemented to expose students to material on prosocial bystander behaviour. Results suggested that most students feel empathy towards bullying victims and acknowledge that they have the power to make a difference. However, participants are reluctant to put ideas into action for fear of bully retaliation and the belief that they cannot rely on support from other peers and school staff. This sense of powerlessness seems to have a cultural component to it, and is more common in male students. Other gender differences were observed: females displayed higher self-efficacy to help and lower moral disengagement levels. Research on cultural influences on bullying and bystander behaviour worldwide is needed, as well as further research on the implications, obstacles and opportunities of gender differences in this regard. Studies on what bystanders need to feel safe when helping bullying victims would also be a valuable resource for anti-bullying intervention efforts

Rare mutations and potentially damaging missense variants in genes encoding fibrillar collagens and proteins involved in their production are candidates for risk for preterm premature rupture of membranes

Preterm premature rupture of membranes (PPROM) is the leading identifiable cause of preterm birth with ~ 40% of preterm births being associated with PPROM and occurs in 1% - 2% of all pregnancies. We hypothesized that multiple rare variants in fetal genes involved in extracellular matrix synthesis would associate with PPROM, based on the assumption that impaired elaboration of matrix proteins would reduce fetal membrane tensile strength, predisposing to unscheduled rupture. We performed whole exome sequencing (WES) on neonatal DNA derived from pregnancies complicated by PPROM (49 cases) and healthy term deliveries (20 controls) to identify candidate mutations/variants. Genotyping for selected variants from the WES study was carried out on an additional 188 PPROM cases and 175 controls. All mothers were self-reported African Americans, and a panel of ancestry informative markers was used to control for genetic ancestry in all genetic association tests. In support of the primary hypothesis, a statistically significant genetic burden (all samples combined, SKAT-O p-value = 0.0225) of damaging/potentially damaging rare variants was identified in the genes of interest—fibrillar collagen genes, which contribute to fetal membrane strength and integrity. These findings suggest that the fetal contribution to PPROM is polygenic, and driven by an increased burden of rare variants that may also contribute to the disparities in rates of preterm birth among African Americans

Evolution of trees and mycorrhizal fungi intensifies silicate mineral weathering.

Forested ecosystems diversified more than 350 Ma to become major engines of continental silicate weathering, regulating the Earth's atmospheric carbon dioxide concentration by driving calcium export into ocean carbonates. Our field experiments with mature trees demonstrate intensification of this weathering engine as tree lineages diversified in concert with their symbiotic mycorrhizal fungi. Preferential hyphal colonization of the calcium silicate-bearing rock, basalt, progressively increased with advancement from arbuscular mycorrhizal (AM) to later, independently evolved ectomycorrhizal (EM) fungi, and from gymnosperm to angiosperm hosts with both fungal groups. This led to 'trenching' of silicate mineral surfaces by AM and EM fungi, with EM gymnosperms and angiosperms releasing calcium from basalt at twice the rate of AM gymnosperms. Our findings indicate mycorrhiza-driven weathering may have originated hundreds of millions of years earlier than previously recognized and subsequently intensified with the evolution of trees and mycorrhizas to affect the Earth's long-term CO(2) and climate history

Discovery of a new radio galaxy within the error box of the unidentified gamma-ray source 3EG J1735-1500

We report the discovery of a new radio galaxy within the location error box of the gamma-ray source 3EG J1735-1500. The galaxy is a double-sided jet source forming a large angle with the line of sight. Optical observations reveal a V ~ 18 magnitude galaxy at the position of the radio core. Although the association with the EGRET source is not confirmed at the present stage, because there is a competing, alternative gamma-ray candidate within the location error contours which is also studied here, the case deserves further attention. The new radio galaxy can be used to test the recently proposed possibility of gamma-ray emitting radio galaxies beyond the already known case of Centaurus A

Interviewing Peter Gow — Dundee, June 24, 2017

This interview presents an initial dialogue about Peter Gow’s trajectory as an anthropologist, trying to bring to light particularly the fieldwork experiences and events that it had not been possible to commenton and explore in the published material. Its aim is to understand more closely the particular ways in which Peter Gow had come to arrive at the insights and the analyses presented in his brilliant ethnographies with the Yine/Piro people of Amazonia