791 research outputs found
Simulations for position-sensitive tracking of rays in scintillators Approach for source reconstruction
The H.E.S.S. II GRB Program
Gamma-ray bursts (GRBs) are some of the most energetic and exotic events in
the Universe, however their behaviour at the highest energies (>10 GeV) is
largely unknown. Although the Fermi-LAT space telescope has detected several
GRBs in this energy range, it is limited by the relatively small collection
area of the instrument. The H.E.S.S. experiment has now entered its second
phase by adding a fifth telescope of 600 m mirror area to the centre of
the array. This new telescope increases the energy range of the array, allowing
it to probe the sub-100 GeV range while maintaining the large collection area
of ground based gamma-ray observatories, essential to probing short-term
variability at these energies. We will present a description of the GRB
observation scheme used by the H.E.S.S. experiment, summarising the behaviour
and performance of the rapid GRB repointing system, the conditions under which
potential GRB repointings are made and the data analysis scheme used for these
observations.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherland
Exome sequencing of an isolated Chilean population affected by Specific Language Impairment (SLI)
Speech and language impairments that are a primary deficit and have no obvious cause (e.g. a comorbid neurological disorder like autism) are diagnosed as Specific Language Impairment (SLI). SLI affects 5–8 % of preschool children and represents a lifelong disability associated with an increased risk of behavioural disorders, social problems and literacy deficits. SLI is highly heritable and twin studies indicate a strong genetic basis. Nonetheless, the underlying genetic mechanisms are expected to be multifactorial and, to date, only three risk variants have been identified. One way to increase the power to detect contributory genetic factors is to study isolated populations derived from relatively recent shared ancestors (founder populations). In 2008, Villanueva described a founder population with a particularly high incidence of SLI (10 times that expected). They inhabit the Robinson Crusoe Island, which lies 677 km to the west of Chile and was colonised in the late 19th century by 8 European and Amerindian families. 77 % of the current island population have a colonising surname and 14 % of marriages involve consanguineous unions. More than 80 % of language impaired individuals can be traced to a pair of founder brothers. This population thus has a short (5-generations) and well documented history and represents a unique resource which could make valuable contributions to the elucidation of genetic mechanisms underpinning SLI. We applied exome sequencing technologies to five language impaired individuals from this population and identified nine nonsynonymous coding changes or splice site mutations that were present in at least three of the five affected individuals sequenced. Sequencing of the entire cohort identified a single non-synonymous coding change that was significantly more frequent in cases than controls (genotype frequencies of 46 and 11 % respectively, p = 4.48 9 10-5). We suggest that this rare coding variant may contribute to the elevated frequency of SLI in this population
We’ve Been Down this Road Before: Evidence on the Health Consequences of Precarious Employment in Industrial Societies, 1840-1920
A large body of international scientific research now indicates that the growth of job insecurity, flexible/temporary work and precarious forms of self-employment have had significant negative consequences for occupational health and safety. What is often overlooked in debates over the ‘changing world of work’ is that today’s widespread use insecure and short term work is not new but represents a return to something more resembling labour markets in Australia, Europe and North America in the 19th and early 20th century. As this paper will seek to show, not only were precarious and exploitive working arrangements common during this period but the adverse effects of these on the health, safety and wellbeing was well documented in government inquiries, medical research, press reports and a variety of other sources. Drawing primarily on Australian and British sources, attention here will focus on casual labourers, sweated garment workers, the self-employed and merchant seamen. The paper highlights the valuable role historical research can play in shedding light on contemporary problems and policy debates.The symposium is organised on behalf of AAHANZBS by the Business and Labour History Group, The University of Sydney, with the financial support of the University’s Faculty of Economics and Business
Core-coupled states and split proton-neutron quasi-particle multiplets in 122-126Ag
Neutron-rich silver isotopes were populated in the fragmentation of a 136Xe
beam and the relativistic fission of 238U. The fragments were mass analyzed
with the GSI Fragment separator and subsequently implanted into a passive
stopper. Isomeric transitions were detected by 105 HPGe detectors. Eight
isomeric states were observed in 122-126Ag nuclei. The level schemes of
122,123,125Ag were revised and extended with isomeric transitions being
observed for the first time. The excited states in the odd-mass silver isotopes
are interpreted as core-coupled states. The isomeric states in the even-mass
silver isotopes are discussed in the framework of the proton-neutron split
multiplets. The results of shell-model calculations, performed for the most
neutron-rich silver nuclei are compared to the experimental data
Solving patients with rare diseases through programmatic reanalysis of genome-phenome data
Reanalysis of inconclusive exome/genome sequencing data increases the diagnosis yield of patients with rare diseases. However, the cost and efforts required for reanalysis prevent its routine implementation in research and clinical environments. The Solve-RD project aims to reveal the molecular causes underlying undiagnosed rare diseases. One of the goals is to implement innovative approaches to reanalyse the exomes and genomes from thousands of well-studied undiagnosed cases. The raw genomic data is submitted to Solve-RD through the RD-Connect Genome-Phenome Analysis Platform (GPAP) together with standardised phenotypic and pedigree data. We have developed a programmatic workflow to reanalyse genome-phenome data. It uses the RD-Connect GPAP’s Application Programming Interface (API) and relies on the big-data technologies upon which the system is built. We have applied the workflow to prioritise rare known pathogenic variants from 4411 undiagnosed cases. The queries returned an average of 1.45 variants per case, which first were evaluated in bulk by a panel of disease experts and afterwards specifically by the submitter of each case. A total of 120 index cases (21.2% of prioritised cases, 2.7% of all exome/genome-negative samples) have already been solved, with others being under investigation. The implementation of solutions as the one described here provide the technical framework to enable periodic case-level data re-evaluation in clinical settings, as recommended by the American College of Medical Genetics
Detailed spectral and morphological analysis of the shell type SNR RCW 86
Aims: We aim for an understanding of the morphological and spectral
properties of the supernova remnant RCW~86 and for insights into the production
mechanism leading to the RCW~86 very high-energy gamma-ray emission. Methods:
We analyzed High Energy Spectroscopic System data that had increased
sensitivity compared to the observations presented in the RCW~86 H.E.S.S.
discovery publication. Studies of the morphological correlation between the
0.5-1~keV X-ray band, the 2-5~keV X-ray band, radio, and gamma-ray emissions
have been performed as well as broadband modeling of the spectral energy
distribution with two different emission models. Results:We present the first
conclusive evidence that the TeV gamma-ray emission region is shell-like based
on our morphological studies. The comparison with 2-5~keV X-ray data reveals a
correlation with the 0.4-50~TeV gamma-ray emission.The spectrum of RCW~86 is
best described by a power law with an exponential cutoff at TeV and a spectral index of ~. A static
leptonic one-zone model adequately describes the measured spectral energy
distribution of RCW~86, with the resultant total kinetic energy of the
electrons above 1 GeV being equivalent to 0.1\% of the initial kinetic
energy of a Type I a supernova explosion. When using a hadronic model, a
magnetic field of ~100G is needed to represent the measured data.
Although this is comparable to formerly published estimates, a standard
E spectrum for the proton distribution cannot describe the gamma-ray
data. Instead, a spectral index of ~1.7 would be required, which
implies that ~erg has been transferred into
high-energy protons with the effective density cm^-3. This
is about 10\% of the kinetic energy of a typical Type Ia supernova under the
assumption of a density of 1~cm^-3.Comment: accepted for publication by A&
Characterizing the gamma-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT
Studying the temporal variability of BL Lac objects at the highest energies
provides unique insights into the extreme physical processes occurring in
relativistic jets and in the vicinity of super-massive black holes. To this
end, the long-term variability of the BL Lac object PKS 2155-304 is analyzed in
the high (HE, 100 MeV 200 GeV)
gamma-ray domain. Over the course of ~9 yr of H.E.S.S observations the VHE
light curve in the quiescent state is consistent with a log-normal behavior.
The VHE variability in this state is well described by flicker noise
(power-spectral-density index {\ss}_VHE = 1.10 +0.10 -0.13) on time scales
larger than one day. An analysis of 5.5 yr of HE Fermi LAT data gives
consistent results ({\ss}_HE = 1.20 +0.21 -0.23, on time scales larger than 10
days) compatible with the VHE findings. The HE and VHE power spectral densities
show a scale invariance across the probed time ranges. A direct linear
correlation between the VHE and HE fluxes could neither be excluded nor firmly
established. These long-term-variability properties are discussed and compared
to the red noise behavior ({\ss} ~ 2) seen on shorter time scales during
VHE-flaring states. The difference in power spectral noise behavior at VHE
energies during quiescent and flaring states provides evidence that these
states are influenced by different physical processes, while the compatibility
of the HE and VHE long-term results is suggestive of a common physical link as
it might be introduced by an underlying jet-disk connection.Comment: 11 pages, 16 figure
Detection of variable VHE gamma-ray emission from the extra-galactic gamma-ray binary LMC P3
Context. Recently, the high-energy (HE, 0.1-100 GeV) -ray emission
from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered
to be modulated with a 10.3-day period, making it the first extra-galactic
-ray binary.
Aims. This work aims at the detection of very-high-energy (VHE, >100 GeV)
-ray emission and the search for modulation of the VHE signal with the
orbital period of the binary system.
Methods. LMC P3 has been observed with the High Energy Stereoscopic System
(H.E.S.S.); the acceptance-corrected exposure time is 100 h. The data set has
been folded with the known orbital period of the system in order to test for
variability of the emission. Energy spectra are obtained for the orbit-averaged
data set, and for the orbital phase bin around the VHE maximum.
Results. VHE -ray emission is detected with a statistical
significance of 6.4 . The data clearly show variability which is
phase-locked to the orbital period of the system. Periodicity cannot be deduced
from the H.E.S.S. data set alone. The orbit-averaged luminosity in the
TeV energy range is erg/s. A luminosity of erg/s is reached during 20% of the orbit. HE and VHE
-ray emissions are anti-correlated. LMC P3 is the most luminous
-ray binary known so far.Comment: 5 pages, 3 figures, 1 table, accepted for publication in A&
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