13,073 research outputs found

    Two micron quadrupole line emission of H2 from the Jovian auroral zone

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    Energetic electron bombardment of the H2 atmosphere in the Jovian auroral zone was studied using a theoretical model for the vibrational-ratational excitation processes. A non-relativistic electron energy deposition program originally developed by Peterson et al. was used. Assuming an incident energy electron spectrum from IUE observations, the calculated intensities of the two micron quadrupole lines from the Jovian auroral zone are shown to be comparable to the intensities of infrared objects in the Orion nebula. Jupiter is fairly dark in the 2 to 2.5 micron spectral range because of strong absorption of cH4 and NH3 vibrational-rotational bands. Consequently, assuming no significant decrease in Jovian auroral activity since the Voyager encounter with Jupiter in 1979, the two micron quadrupole emission of H2 may be observable by ground-based telescope through the two micron atmospheric window

    'I just want a job' : what do we really know about young people in jobs without training?

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    Over recent years, a central concern of policy has been to drive up post-16 participation rates in full-time education and address the needs of young people not in education, employment or training (NEET). As a result, young people who enter work which is classified as 'without training' at 16/17 have largely been ignored. However, the decision to Raise the Participation Age (RPA) for continuing in learning for all 17-year olds from 2013 and for all 18-year olds from 2015 in England, together with a growing unease about the impact of the current recession on youth unemployment rates, have revived interest in the 'jobs without training' (JWT) group. This paper draws on the findings from two studies: first, a qualitative study in two contrasting local labour markets, of young people in JWT, together with their employers and parents; and second, an evaluation of the Learning Agreement Pilots (LAP), which was the first policy initiative in England targeted at the JWT group. Both studies reveal a dearth of understanding about early labour market entrants and a lack of policy intervention and infrastructure to support the needs of the JWT group throughout the UK. From this, it is concluded that questionable assumptions have been made about the composition and the aspirations of young people in JWT, and their employers, on the basis of little or no evidence. As a consequence, a policy 'quick fix' to satisfy the RPA agenda will not easily be achieved. If the decision to raise the participation age is adopted also by the Welsh and Scottish parliaments, similar challenges may have to be faced

    Do Small-mass Neutrinos participate in Gauge Transformations?

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    Neutrino oscillation experiments presently suggest that neutrinos have a small but finite mass. If neutrinos are to have mass, there should be a Lorentz frame in which they can be brought to rest. This paper discusses how Wigner's little groups can be used to distinguish between massive and massless particles. We derive a representation of the SL(2,c) group which separates out the two sets of spinors contained therein. One set is gauge dependent. The other set is gauge-invariant and represents polarized neutrinos. We show that a similar calculation can be done for the Dirac equation. In the large-momentum/zero-mass limit, the Dirac spinors can be separated into large and small components. The large components are gauge invariant, while the small components are not. These small components represent spin-12\frac{1}{2} non-zero mass particles. If we renormalize the large components, these gauge invariant spinors again represent the polarization of neutrinos. Massive neutrinos cannot be invariant under gauge transformations.Comment: 15 page

    Limits on stable iron in Type\,Ia supernovae from NIR spectroscopy

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    We obtained optical and near-infrared spectra of Type\,Ia supernovae (SNe\,Ia) at epochs ranging from 224 to 496 days after the explosion. The spectra show emission lines from forbidden transitions of singly ionised iron and cobalt atoms. We used non-local thermodynamic equilibrium (NLTE) modelling of the first and second ionisation stages of iron, nickel, and cobalt to fit the spectra using a sampling algorithm allowing us to probe a broad parameter space. We derive velocity shifts, line widths, and abundance ratios for iron and cobalt. The measured line widths and velocity shifts of the singly ionised ions suggest a shared emitting region. Our data are fully compatible with radioactive 56^{56}Ni decay as the origin for cobalt and iron. We compare the measured abundance ratios of iron and cobalt to theoretical predictions of various SN\,Ia explosion models. These models include, in addition to 56^{56}Ni, different amounts of 57^{57}Ni and stable 54,56^{54,56}Fe. We can exclude models that produced only 54,56^{54,56}Fe or only 57^{57}Ni in addition to 56^{56}Ni. If we consider a model that has 56^{56}Ni, 57^{57}Ni, and 54,56^{54,56}Fe then our data imply that these ratios are 54,56^{54,56}Fe / 56^{56}Ni =0.272±0.086=0.272\pm0.086 and 57^{57}Ni / 56^{56}Ni =0.032±0.011=0.032\pm0.011.Comment: 10 pages, 7 figures, Accepted for publication in A&

    Detecting the signatures of helium in type Iax supernovae

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    Recent studies have argued that the progenitor system of type Iax supernovae must consist of a carbon-oxygen white dwarf accreting from a helium star companion. Based on existing explosion models invoking the pure deflagration of carbon-oxygen white dwarfs, we investigate the likelihood of producing spectral features due to helium in type Iax supernovae. From this scenario, we select those explosion models producing ejecta and 56^{56}Ni masses that are broadly consistent with those estimated for type Iax supernovae (0.014 - 0.478~MM_{\odot} and 0.003\sim0.003 - 0.183~MM_{\odot}, respectively). To this end, we present a series of models of varying luminosities (18.4MV14.5-18.4 \lesssim M_{\rm{V}} \lesssim -14.5~mag) with helium abundances accounting for up to \sim36\% of the ejecta mass, and covering a range of epochs beginning a few days before B-band maximum to approximately two weeks after maximum. We find that the best opportunity for detecting \ion{He}{i} features is at near-infrared wavelengths, and in the post-maximum spectra of the fainter members of this class. We show that the optical spectrum of SN~2007J is potentially consistent with a large helium content (a few 102 M^{-2}~M_{\odot}), but argue that current models of accretion and material stripping from a companion struggle to produce compatible scenarios. We also investigate the presence of helium in all objects with near-infrared spectra. We show that SNe~2005hk, 2012Z, and 2015H contain either no helium or their helium abundances are constrained to much lower values (\lesssim103 M^{-3}~M_{\odot}). Our results demonstrate the differences in helium content among type Iax supernovae, perhaps pointing to different progenitor channels. Either SN~2007J is an outlier in terms of its progenitor system, or it is not a true member of the type Iax supernova class.Comment: 15 pages, 12 figures, 2 tables. Accepted for publication in Astronomy and Astrophysic

    Keep Calm and Carry On: Children’s Self-Regulation in Early Years Settings

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    Early childhood education and care (ECEC) in Ireland promotes the development and education of children aged from birth to six years. Over a third of nine-month-olds and over half of three-year-olds experience some form of non-parental care in Ireland (Williams, Murray, McCrory and McNally, 2013), with type and duration of ECEC experiences varying considerably. However, almost all children aged between three and four years avail of the free pre-school year which was introduced in January 2010, administered by the Department of Children and Youth Affairs. Irish ECEC policy is developing rapidly. Responsibility for policy developments in the ECEC sector is shared by the Department of Education and Skills (DES) and the Department of Children and Youth Affairs (DCYA). Two key frameworks underpinning ECEC provision are Síolta, the national quality framework for Early Childhood Education (Centre for Early Childhood Development and Education, 2006) and Aistear, the early childhood curriculum framework (National Council for Curriculum and Assessment, 2009). Implementation of the early childhood curriculum is not mandatory, however, in ECEC settings (French, 2013)..

    Nebular spectroscopy of SN 2014J: Detection of stable nickel in near infrared spectra

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    We present near infrared (NIR) spectroscopy of the nearby supernova 2014J obtained \sim450 d after explosion. We detect the [Ni II] 1.939 μ\mum line in the spectra indicating the presence of stable 58^{58}Ni in the ejecta. The stable nickel is not centrally concentrated but rather distributed as the iron. The spectra are dominated by forbidden [Fe II] and [Co II] lines. We use lines, in the NIR spectra, arising from the same upper energy levels to place constraints on the extinction from host galaxy dust. We find that that our data are in agreement with the high AVA_V and low RVR_V found in earlier studies from data near maximum light. Using a 56^{56}Ni mass prior from near maximum light γ\gamma-ray observations, we find \sim0.05 M_\odot of stable nickel to be present in the ejecta. We find that the iron group features are redshifted from the host galaxy rest frame by \sim600 km s1^{-1}.Comment: 6 pages, 4 figures, submitted to A&

    Condition Rating Prediction Using an Interactive Deterioration Model Development Package

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    This paper presents an advanced method to determine explanatory variables required for developing deterioration models without the interference of human bias. Although a stationary set of explanatory variables is ideal for long-term monitoring and asset management, the penalty regression results vary annually due to the innate bias in the inspection data. In this study, weighting factors were introduced to consider the inspection data collected for several years, and the most stationary set was identified. To manage the substantial amount of inspection data effectively, we proposed a software package referred to as the Deterioration Model Development Package (DMDP). The objective of the DMDP is to provide a convenient platform for users to process and investigate bridge inspection data. Using the standardized data interpretation, the user can update an initial dataset for the deterioration model development when new inspection data are archived. The deterministic method and several stochastic approaches were included for the development of the deterioration models. The performances of the investigated methods were evaluated by estimating the error between the predicted and inspected condition ratings; further, this error was used for estimating the most effective number of explanatory variables for a given number of bridges
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