6,191 research outputs found

    Two superluminous supernovae from the early universe discovered by the Supernova Legacy Survey

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    We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and gives a rare glimpse into the restframe ultraviolet where these supernovae put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both supernovae have similar observer-frame griz lightcurves, which map to restframe lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and declining over a similar timescale. The lightcurves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra to theoretical models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of SNLS 06D4eu and SCP 06F6, and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10^52 ergs, is also favored. Normal mechanisms of powering core- collapse or thermonuclear supernovae do not seem to work for these supernovae. We consider models powered by 56Ni decay and interaction with circumstellar material, but find that the creation and spin-down of a magnetar with a period of 2ms, magnetic field of 2 x 10^14 Gauss, and a 3 solar mass progenitor provides the best fit to the data.Comment: ApJ, accepted, 43 pages, 15 figure

    Efficiency of hair snares and camera traps to survey mesocarnivore populations

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    Mammalian carnivore communities affect entire ecosystem functioning and structure. However, their large spatial requirements, preferred habitats, low densities, and elusive behavior deem them difficult to study. In recent years, noninvasive techniques have become much more common as they can be used to monitor multiple carnivore species across large areas at a relatively modest cost. Hair snares have the potential to fulfill such requirements, but have rarely been tested in Europe. Our objective was to quantitatively assess the effectiveness of hair snares for surveying mesocarnivores in the Iberian Peninsula (Southwestern Europe), by comparison with camera-trapping. We used an occupancy modeling framework to assess method-specific detectability and occupancy estimates and hypothesized that detection probabilities would be influenced by season, sampling method, and habitat-related variables. A total of 163 hair samples were collected, of which 136 potentially belonged to mesocarnivores. Genetic identification success varied with diagnostic method: 25.2 % using mitochondrial CR, and 9.9 % using the IRBP nuclear gene. Naïve occupancy estimates were, in average, 5.3 ± 1.2 times higher with camera-trapping than with hair-snaring, and method-specific detection probabilities revealed that camera traps were, in average, 6.7 ± 1.1 times more effective in detecting target species. Overall, few site-specific covariates revealed significant effects on mesocarnivore detectability. Camera traps were a more efficient method for detecting mesocarnivores and estimating their occurrence when compared to hair snares. To improve hair snares' low detection probabilities, we suggest increasing the number of sampling occasions and the frequency at which hair snares are checked. With some refinements to increase detection rates and the success of genetic identification, hair-snaring methods may be valuable for providing deeper insights into population parameters, attained through adequate analysis of genetic information, that is not possible with camera traps.This work was partially supported by a PhD grant from the Fundação para a Ciência e a Tecnologia (FCT) to PM (SFRH/BD/37795/2007) and two research projects, one from the Spanish National Plan (project ref: CGL2009-10741) funded by the Spanish Ministry of Science and Innovation and EU-FEDER funds, and one from the Spanish Organismo Autónomo Parques Nacionales (project ref: OAPN 352/2011). PCA was supported by the Luso-American Development Foundation (FLAD) and FCT sabbatical grant SFRH/BSAB/1278/2012.Peer Reviewe

    Interpreting social determinants: Emergent properties and adolescent risk behaviour

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    A link between adversity, including low socio-economic status, and behaviours which carry health risks, such as alcohol consumption, has often been observed. The causes of this link are, however, poorly understood, making it difficult to explain why the association is often not linear and why there is so much variability between groups and individuals facing similar adversity. We investigate the use of the concept of emergent properties in explaining the link and its non-linear nature. `Emergent properties’ arise from the interaction of factors or items in a high-level system which, as a result, has qualities possessed by none of the individual factors. We apply a mixed methods approach to examine the association of an example emergent property, hope, and alcohol consumption among adolescents in a rural South African site. We found that among adolescents living in similar contexts, there was enough variance in reported levels of hope, that an association with alcohol use could be identified. This result is cause for optimism regarding the potential use of emergent properties in explaining variations in risk behaviour. Improving our measurement of emergent properties is perhaps the biggest challenge facing this approach. More work is needed to take further the task of identifying emergent properties capable of distilling the influence of lower level variables into single measures useful for analysis and policy purposes

    The scatter about the "Universal" dwarf spheroidal mass profile: A kinematic study of the M31 satellites, And V and And VI

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    While the satellites of the Milky Way (MW) have been shown to be largely consistent in terms of their mass contained within one half--light radius (M_{half}) with a "Universal" mass profile, a number of M31 satellites are found to be inconsistent with such relations, and seem kinematically colder in their central regions than their MW cousins. In this work, we present new kinematic and updated structural properties for two M31 dSphs, And V and And VI using data from the Keck Low Resolution Imaging Spectrograph (LRIS) and the DEep Imaging Multi-Object Spectrograph (DEIMOS) instruments and the Subaru Suprime-Cam imager. We measure systemic velocities of v_r=-393.1+/-4.2km/s and -344.8+/-2.5km/s, and dispersions of sigma_v=11.5{+5.3}{-4.4}km/s and sigma_v=9.4{+3.2}{-2.4}km/s for And V and And VI respectively, meaning these two objects are consistent with the trends in sigma_v and r_{half} set by their MW counterparts. We also investigate the nature of this scatter about the MW dSph mass profiles for the "Classical" (i.e. M_V<-8) MW and M31 dSphs. When comparing both the "classical" MW and M31 dSphs to the best--fit mass profiles in the size--velocity dispersion plane, we find general scatter in both the positive (i.e. hotter) and negative (i.e. colder) directions from these profiles. However, barring one exception (CVnI) only the M31 dSphs are found to scatter towards a colder regime, and, excepting the And I dSph, only MW objects scatter to hotter dispersions. We also note that the scatter for the combined population is greater than expected from measurement errors alone. We assess this divide in the context of the differing disc-to-halo mass (i.e. stars and baryons to total virial mass) ratios of the two hosts and argue that the underlying mass profiles for dSphs differ from galaxy to galaxy, and are modified by the baryonic component of the host.Comment: 15 pages, 8 figures. Small modifications made for referee report. Accepted for publication in MNRAS (29/06/2011

    Real Oscillations of Virtual Neutrinos

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    We study the conditions for neutrino oscillations in a field theoretical approach by taking into account that only the neutrino production and detection processes, which are localized in space around the coordinates x⃗P\vec{x}_P and x⃗D\vec{x}_D, respectively, can be manipulated. In this sense the neutrinos whose oscillations are investigated appear as virtual lines connecting production with detection in the total Feynman graph and all neutrino fields or states to be found in the discussion are mass eigenfields or eigenstates. We perform a thorough examination of the integral over the spatial components of the inner neutrino momentum and show that in the asymptotic limit L=∣x⃗D−x⃗P∣→∞L=|\vec{x}_D - \vec{x}_P| \rightarrow \infty the virtual neutrinos become ``real'' and under certain conditions the usual picture of neutrino oscillations emerges without ambiguities.Comment: 12 pages, pure LaTeX file, no figure

    Survival in patients with pulmonary arterial hypertension treated with first-line bosentan

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    Background  Pulmonary arterial hypertension (PAH) is a devastating disease of the small pulmonary arteries and arterioles, characterized by intimal fibrosis, medial hypertrophy and plexiform lesions. When untreated both the idiopathic form (IPAH, formerly termed primary pulmonary hypertension, PPH) and PAH related to various other conditions such as scleroderma (SSc) often take a progressive course with high mortality. There is ongoing search for disease-specific treatments that are able to improve survival in these patients. The oral dual endothelin (ET A /ET B ) antagonist bosentan has been shown to improve exercise capacity, time to clinical worsening, haemodynamics and quality of life in short-term studies. Materials and methods  To determine the long-term effects of bosentan on survival, patients from the two double-blind, randomized trials and their open-label extensions, treated with first-line bosentan, were followed for up to 3 years. Data on survival were collected between September 1999 (first patient included in the placebo-controlled trials) and December 2002. Vital status was verified in each patient. The survival cohorts of these patients were compared with either the predicted survival for each patient based on an equation from the National Institutes of Health (NIH) PPH registry or with historical controls. Results  Observed survival up to 36 months was reported as a Kaplan-Meier estimate in three cohorts: (1) In 169 PPH patients treated with first-line bosentan, 1- and 2-year survival was 96% and 89%, respectively, vs. predicted untreated survival at 1 and 2 years of 69% and 57%, respectively; (2) in 50 patients with PAH associated with SSc (PAH-SSc), 1-, 2- and 3-year survival was 82%, 67% and 64%, respectively, vs. ∼45%, ∼35% and ∼28%, respectively, from registry data of untreated PAH-SSc patients; and (3) in 139 PPH patients in WHO functional class III, 1- and 2-year survival was 97% and 91%, respectively, vs. 91% and 84% in a historical cohort of 346 patients treated with epoprostenol in five major referral centres. Conclusions  The present analyses suggest that first-line bosentan therapy, followed by the addition of other disease-specific therapies as required, improves survival in patients with advanced PAH. Eur J Clin Invest 2006; 36 (Suppl. 3): 10 –15Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71978/1/j.1365-2362.2006.01688.x.pd

    Mental health research projects: a practical integration of mental health into a medical curriculum

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    Abstract of a paper presented at the 65th Annual National Conference of Indian Psychiatric Society, Bangalor, 10-13 Jan, 2013. Aims aJld Objectives: The University of Wollongong (UoW) graduate-entry medical course embeds research and critical analysis within the curriculum, concluding with students undertaking a regional/ nlrsl conmlUnity-based ro earch project. Students are encouraged to design a research project of interest to them and the local community. T.his Indy analyzed whether conducting research projects enhanced learning/understanding about rural/regional mental health issues amongst UoW medical students

    Parents, children and the porous boundaries of the sexual family in law and popular culture

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    This article focuses on a perceived ideological overlap between popular cultural and judicial treatments of sex and conjugality that contributes to a discursive construction of parenthood and parenting. The author perceives that in both legal and popular cultural texts, there is a sense in which notions of ‘natural’ childhood are discursively constituted as being put at risk by those who reproduce outside of dominant sexual norms, and that signs of normative sexuality (typically in the form of heterosexual coupling) may be treated as a sign of safety. These ideas are rooted in ancient associations between fertility, sexuality and femininity that can also be traced in the historical development of the English language. With the help of commentators such as Martha Fineman, the article situates parents and children within a discourse of family which prioritises conjugality, with consequences for the ways in which the internal and external boundaries of families are delineated

    Effects of neutrino oscillations and neutrino magnetic moments on elastic neutrino-electron scattering

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    We consider elastic antineutrino-electron scattering taking into account possible effects of neutrino masses and mixing and of neutrino magnetic moments and electric dipole moments. Having in mind antineutrinos produced in a nuclear reactor we compute, in particular, the weak-electromagnetic interference terms which are linear in the magnetic (electric dipole) moments and also in the neutrino masses. We show that these terms are, however, suppressed compared to the pure weak and electromagnetic cross section. We also comment upon the possibility of using the electromagnetic cross section to investigate neutrino oscillations.Comment: 12 pages, REVTEX file, no figures, submitted to Phys.Rev.
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