2,357 research outputs found
Ukupni i specifični mortalitet u radnika izloženih azbestu od 1907. do 1985. godine
Total and cause-specific mortality data for the 1907 -1985 period were compared between cohorts of male asbestos-cement workers (N = 1908) and referents (N = 726), using Poisson regression modelling. The rate ratio (RR) for total mortality was significantly increased (1.3) among the exposed workers, as was mortality from non-malignant respiratory disease (RR= 2.2). Numerically, but not statistically significantly, raised ratios were found for respiratory (RR= 1.6) and gastrointestinal (RR= 1.3) cancers. The trend in the rate ratio for total mortality with time was better fitted with a curved line, than with a monotonic one, because of a period of increased risk up to the 1950s, and another one starting after 1970.Ukupni i specifični mortalitet za razdoblje od 1907. do 1985. godine uspoređen je u kohortama muških radnika koji su bili izloženi azbestu (N = 1908) s kontrolama (N = 726) pomoću Poissonove regresijske analize. Koeficijent regresije (RR) za ukupni mortalitet, kao i mortalitet od nemalignih respiratornih bolesti bio je statistički značajno viši i iznosio je 1,3, odnosno 2,2. Povećanje ovog koeficijenta nađeno je i za plućni (1,6) i gastrointestinalni karcinom (1,3), ali vrijednosti nisu statistički značajne
Exploring the feasibility and acceptability of a sleep wearable headband among a community sample of chronic pain individuals: An at-home observational study
Background
Chronic pain conditions affect up to one third of the adult population in the United Kingdom. Sleep problems are prevalent and negatively impact quality of life. Lack of standardised tools for routine screening and assessment of sleep changes have been a barrier for sleep management. Novel sleep wearables offer an exciting and accessible way to measure sleep but have not been tested outside of the consumer-led landscape and are not commonly used in research and clinical settings.
Aims
The study aimed to explore the feasibility and acceptability of a sleep monitoring headband (Dreem 2) utilising EEG technology and accompanying smartphone application among a cohort of adults with chronic pain.
Results
Twenty-one adults (81% women) completed a one-week home sleep study using a sleep headband and accompanying app. Ninety per cent of participants met the pre-defined requirement of two-night's sleep recording. All participants recorded one night of sleep data via the sleep headband. The majority (76%) of participants were satisfied with the sleep study, and 86% of participants were willing to wear the headband longer than the 2-night minimum requirement. Finally, 76% reported the headband as ‘somewhat’ or ‘extremely’ comfortable whist awake; 57% rated the headband as comfortable during sleep.
Conclusion
The Dreem 2 headband appears to be a feasible and acceptable means of collecting sleep measurements among individuals with chronic pain, despite common sleep disturbances. These devices may have utility for screening, assessment and monitoring in research and practice. Further research is needed to provide guidelines and training for integration
Robust photometric redshift determinations of gamma-ray burst afterglows at z > 2
Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will
originate at redshifts greater than 5 yet a number of high redshift candidates
may be left unconfirmed due to the lack of measured redshifts. Here we
introduce our code, GRBz, a method of simultaneous multi-parameter fitting of
GRB afterglow optical and near infrared, spectral energy distributions. It
allows for early determinations of the photometric redshift, spectral index and
host extinction to be made. We assume that GRB afterglow spectra are well
represented by a power-law decay and model the effects of absorption due to the
Lyman forest and host extinction. We use a genetic algorithm-based routine to
simultaneously fit the parameters of interest, and a Monte Carlo error
analysis. We use GRBs of previously determined spectroscopic redshifts to prove
our method, while also introducing new near infrared data of GRB 990510 which
further constrains the value of the host extinction. Our method is effective in
estimating the photometric redshift of GRBs, relatively unbiased by assumptions
of the afterglow spectral index or the host galaxy extinction. Monte Carlo
error analysis is required as the method of error estimate based on the optimum
population of the genetic algorithm underestimates errors significantly.Comment: Accepted to A&A: 8 pages, 5 figure
The optical afterglow of the short gamma-ray burst GRB 050709
It has long been known that there are two classes of gamma-ray bursts (GRBs),
mainly distinguished by their durations. The breakthrough in our understanding
of long-duration GRBs (those lasting more than ~2 s), which ultimately linked
them with energetic Type Ic supernovae, came from the discovery of their
long-lived X-ray and optical afterglows, when precise and rapid localizations
of the sources could finally be obtained. X-ray localizations have recently
become available for short (duration <2 s) GRBs, which have evaded optical
detection for more than 30 years. Here we report the first discovery of
transient optical emission (R-band magnitude ~23) associated with a short
burst; GRB 050709. The optical afterglow was localized with subarcsecond
accuracy, and lies in the outskirts of a blue dwarf galaxy. The optical and
X-ray afterglow properties 34 h after the GRB are reminiscent of the afterglows
of long GRBs, which are attributable to synchrotron emission from
ultrarelativistic ejecta. We did not, however, detect a supernova, as found in
most nearby long GRB afterglows, which suggests a different origin for the
short GRBs.Comment: 11 pages, 3 figures, press material at http://www.astro.ku.dk/dark
The distribution of equivalent widths in long GRB afterglow spectra
The extreme brightness of gamma-ray burst (GRB) afterglows and their simple
spectral shape make them ideal beacons to study the interstellar medium of
their host galaxies through absorption line spectroscopy. Using 69
low-resolution GRB afterglow spectra, we conduct a study of the rest-frame
equivalent width (EW) distribution of features with an average rest-frame EW
larger than 0.5 A. To compare an individual GRB with the sample, we develop EW
diagrams as a graphical tool, and we give a catalogue with diagrams for the 69
spectra. We introduce a line strength parameter (LSP) that allows us to
quantify the strength of the absorption features as compared to the sample by a
single number. Using the distributions of EWs of single-species features, we
derive the distribution of column densities by a curve of growth (CoG) fit. We
find correlations between the LSP and the extinction of the GRB, the UV
brightness of the host galaxies and the neutral hydrogen column density.
However, we see no significant evolution of the LSP with the redshift. There is
a weak correlation between the ionisation of the absorbers and the energy of
the GRB, indicating that, either the GRB event is responsible for part of the
ionisation, or that galaxies with high-ionisation media produce more energetic
GRBs. Spectral features in GRB spectra are, on average, 2.5 times stronger than
those seen in QSO intervening damped Lyman-alpha (DLA) systems and slightly
more ionised. In particular we find larger excess in the EW of CIV1549 relative
to QSO DLAs, which could be related to an excess of Wolf-Rayet stars in the
environments of GRBs. From the CoG fitting we obtain an average number of
components in the absorption features of GRBs of 6.00(-1.25,+1.00). The most
extreme ionisation ratios in our sample are found for GRBs with low neutral
hydrogen column density, which could be related to ionisation by the GRB
emission.Comment: 37 pages, 31 figures, 15 tables. Accepted for publication in Astonomy
and Astrophysic
A monument to the player: Preserving a landscape of socio-cultural capital in the transitional MMORPG
This is the pre-print version of the Article. The official published version can be accessed from the links below - Copyright @ 2012 Taylor & Francis LtdMassively multiplayer online role-playing games (MMORPGs) produce dynamic socio-ludic worlds that nurture both culture and gameplay to shape experiences. Despite the persistent nature of these games, however, the virtual spaces that anchor these worlds may not always be able to exist in perpetuity. Encouraging a community to migrate from one space to another is a challenge now facing some game developers. This paper examines the case of Guild Wars® and its “Hall of Monuments”, a feature that bridges the accomplishments of players from the current game to the forthcoming sequel. Two factor analyses describe the perspectives of 105 and 187 self-selected participants. The results reveal four factors affecting attitudes towards the feature, but they do not strongly correlate with existing motivational frameworks, and significant differences were found between different cultures within the game. This informs a discussion about the implications and facilitation of such transitions, investigating themes of capital, value perception and assumptive worlds. It is concluded that the way subcultures produce meaning needs to be considered when attempting to preserve the socio-cultural landscape
A comparison of Northeast Atlantic killer whale (Orcinus orca) stereotyped call repertoires
Funding for data collection was provided by the BBC Natural History Unit, Fundação para a Ciência e a Tecnologia (grant number SFRH/BD/30303/2006), the Icelandic Research Fund (i. Rannsóknasjóður) through a START Postdoctoral Fellowship (grant number 120248042) and a Project Grant (grant number 163060‐051), the National Geographic Global Exploration Fund (grant number GEFNE65‐12), a Marie Curie International Incoming Fellowship (project number 297116), the Office of Naval Research (grant number N00014‐08‐1‐0984), and a Russell Trust Award from the University of St. Andrews.Killer whale call repertoires can provide information on social connections among groups and populations. Killer whales in Iceland and Norway exhibit similar ecology and behavior, are genetically related, and are presumed to have been in contact before the collapse of the Atlanto-Scandian herring stock in the 1960s. However, photo-identification suggests no recent movements between Iceland and Norway but regular movement between Iceland and Shetland. Acoustic recordings collected between 2005 and 2016 in Iceland, Norway, and Shetland were used to undertake a comprehensive comparison of call repertoires of Northeast Atlantic killer whales. Measurements of time and frequency parameters of calls from Iceland (n = 4,037) and Norway (n = 1,715) largely overlapped in distribution, and a discriminant function analysis had low correct classification rate. No call type matches were confirmed between Iceland and Norway or Shetland and Norway. Three call types matched between Iceland and Shetland. Therefore, this study suggests overall similarities in time and frequency parameters but some divergence in call type repertoires. This argues against presumed past contact between Icelandic and Norwegian killer whales and suggests that they may not have been one completely mixed population.PostprintPeer reviewe
Spectrophotometric analysis of GRB afterglow extinction curves with X-shooter
In this work we use gamma-ray burst (GRB) afterglow spectra observed with the
VLT/X-shooter spectrograph to measure rest-frame extinction in GRB
lines-of-sight by modeling the broadband near-infrared (NIR) to X-ray afterglow
spectral energy distributions (SEDs). Our sample consists of nine Swift GRBs,
eight of them belonging to the long-duration and one to the short-duration
class. Dust is modeled using the average extinction curves of the Milky Way and
the two Magellanic Clouds. We derive the rest-frame extinction of the entire
sample, which fall in the range .
Moreover, the SMC extinction curve is the preferred extinction curve template
for the majority of our sample, a result which is in agreement with those
commonly observed in GRB lines-of-sights. In one analysed case (GRB 120119A),
the common extinction curve templates fail to reproduce the observed
extinction. To illustrate the advantage of using the high-quality X-shooter
afterglow SEDs over the photometric SEDs, we repeat the modeling using the
broadband SEDs with the NIR-to-UV photometric measurements instead of the
spectra. The main result is that the spectroscopic data, thanks to a
combination of excellent resolution and coverage of the blue part of the SED,
are more successful in constraining the extinction curves and therefore the
dust properties in GRB hosts with respect to photometric measurements. In all
cases but one the extinction curve of one template is preferred over the
others. We show that the modeled values of the extinction and the spectral
slope, obtained through spectroscopic and photometric SED analysis, can differ
significantly for individual events. Finally we stress that, regardless of the
resolution of the optical-to-NIR data, the SED modeling gives reliable results
only when the fit is performed on a SED covering a broader spectral region.Comment: 17 pages, 7 figures, 4 tables, accepted for publication in Astronomy
& Astrophysic
The optically unbiased GRB host (TOUGH) survey. III. Redshift distribution
We present 10 new gamma-ray burst (GRB) redshifts and another five redshift
limits based on host galaxy spectroscopy obtained as part of a large program
conducted at the Very Large Telescope (VLT). The redshifts span the range 0.345
< z < 2.54. Three of our measurements revise incorrect values from the
literature. The homogeneous host sample researched here consists of 69 hosts
that originally had a redshift completeness of 55% (with 38 out of 69 hosts
having redshifts considered secure). Our project, including VLT/X-shooter
observations reported elsewhere, increases this fraction to 77% (53/69), making
the survey the most comprehensive in terms of redshift completeness of any
sample to the full Swift depth, analyzed to date. We present the cumulative
redshift distribution and derive a conservative, yet small, associated
uncertainty. We constrain the fraction of Swift GRBs at high redshift to a
maximum of 14% (5%) for z > 6 (z > 7). The mean redshift of the host sample is
assessed to be > 2.2, with the 10 new redshifts reducing it significantly.
Using this more complete sample, we confirm previous findings that the GRB rate
at high redshift (z > 3) appears to be in excess of predictions based on
assumptions that it should follow conventional determinations of the star
formation history of the universe, combined with an estimate of its likely
metallicity dependence. This suggests that either star formation at high
redshifts has been significantly underestimated, for example due to a dominant
contribution from faint, undetected galaxies, or that GRB production is
enhanced in the conditions of early star formation, beyond that usually
ascribed to lower metallicity.Comment: 12 pages, 19 figures. ApJ, in pres
First observation of excited states in 173Hg
The neutron-deficient nucleus 173Hg has been studied following
fusion-evaporation reactions. The observation of gamma rays decaying from
excited states are reported for the first time and a tentative level scheme is
proposed. The proposed level scheme is discussed within the context of the
systematics of neighbouring neutron-deficient Hg nuclei. In addition to the
gamma-ray spectroscopy, the alpha decay of this nucleus has been measured
yielding superior precision to earlier measurements.Comment: 5 pages, 4 figure
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