426 research outputs found
Predisposing and precipitating risk factors for delirium in gastroenterology and hepatology: Subgroup analysis of 718 patients from a hospital-wide prospective cohort study
BACKGROUND AND AIMS
Delirium is the most common acute neuropsychiatric syndrome in hospitalized patients. Higher age and cognitive impairment are known predisposing risk factors in general hospital populations. However, the interrelation with precipitating gastrointestinal (GI) and hepato-pancreato-biliary (HPB) diseases remains to be determined.
PATIENTS AND METHODS
Prospective 1-year hospital-wide cohort study in 29'278 adults, subgroup analysis in 718 patients hospitalized with GI/HPB disease. Delirium based on routine admission screening and a DSM-5 based construct. Regression analyses used to evaluate clinical characteristics of delirious patients.
RESULTS
Delirium was detected in 24.8% (178/718). Age in delirious patients (median 62 years [IQR 21]) was not different to non-delirious (median 60 years [IQR 22]), p = 0.45). Dementia was the strongest predisposing factor for delirium (OR 66.16 [6.31-693.83], p < 0.001). Functional impairment, and at most, immobility increased odds for delirium (OR 7.78 [3.84-15.77], p < 0.001). Patients with delirium had higher in-hospital mortality rates (18%; OR 39.23 [11.85-129.93], p < 0.001). From GI and HPB conditions, cirrhosis predisposed to delirium (OR 2.11 [1.11-4.03], p = 0.023), while acute renal failure (OR 4.45 [1.61-12.26], p = 0.004) and liver disease (OR 2.22 [1.12-4.42], p = 0.023) were precipitators. Total costs were higher in patients with delirium (USD 30003 vs. 10977; p < 0.001).
CONCLUSION
Delirium in GI- and HPB-disease was not associated with higher age per se, but with cognitive and functional impairment. Delirium needs to be considered in younger adults with acute renal failure and/or liver disease. Clinicians should be aware about individual risk profiles, apply preventive and supportive strategies early, which may improve outcomes and lower costs
Physics of the Galactic Center Cloud G2, on its Way towards the Super-Massive Black Hole
The origin, structure and evolution of the small gas cloud, G2, is
investigated, that is on an orbit almost straight into the Galactic central
supermassive black hole (SMBH). G2 is a sensitive probe of the hot accretion
zone of Sgr A*, requiring gas temperatures and densities that agree well with
models of captured shock-heated stellar winds. Its mass is equal to the
critical mass below which cold clumps would be destroyed quickly by
evaporation. Its mass is also constrained by the fact that at apocenter its
sound crossing timescale was equal to its orbital timescale. Our numerical
simulations show that the observed structure and evolution of G2 can be well
reproduced if it formed in pressure equilibrium with the surrounding in 1995 at
a distance from the SMBH of 7.6e16 cm. If the cloud would have formed at
apocenter in the 'clockwise' stellar disk as expected from its orbit, it would
be torn into a very elongated spaghetti-like filament by 2011 which is not
observed. This problem can be solved if G2 is the head of a larger, shell-like
structure that formed at apocenter. Our numerical simulations show that this
scenario explains not only G2's observed kinematical and geometrical properties
but also the Br_gamma observations of a low surface brightness gas tail that
trails the cloud. In 2013, while passing the SMBH G2 will break up into a
string of droplets that within the next 30 years mix with the surrounding hot
gas and trigger cycles of AGN activity.Comment: 22 pages, 13 figures, submitted to Ap
Simulations of the Origin and Fate of the Galactic Center Cloud G2
We investigate the origin and fate of the recently discovered gas cloud G2
close to the Galactic Center. Our hydrodynamical simulations focussing on the
dynamical evolution of the cloud in combination with currently available
observations favor two scenarios: a Compact Cloud which started around the year
1995 and a Spherical Shell of gas, with an apocenter distance within the
disk(s) of young stars and a radius of a few times the size of the Compact
Cloud. The former is able to explain the detected signal of G2 in the
position-velocity diagram of the Br gamma emission of the year 2008.5 and
2011.5 data. The latter can account for both, G2's signal as well as the
fainter extended tail-like structure G2t seen at larger distances from the
black hole and smaller velocities. In contrast, gas stripped from a compact
cloud by hydrodynamical interactions is not able to explain the location of the
detected G2t emission in the observed position-velocity diagrams. This favors
the Spherical Shell Scenario and might be a severe problem for the Compact
Cloud as well as the so-called Compact Source Scenario. From these first
idealized simulations we expect a roughly constant feeding of the supermassive
black hole through a nozzle-like structure over a long period, starting shortly
after the closest approach in 2013.51 for the Compact Cloud. If the matter
accretes in the hot accretion mode, we do not expect a significant boost of the
current activity of Sgr A* for the Compact Cloud model, but a boost of the
average infrared and X-ray luminosity by roughly a factor of 80 for the
Spherical Shell scenario with order of magnitude variations on a timescale of a
few months. The near-future evolution of the cloud will be a sensitive probe of
the conditions of the gas distribution in the milli-parsec environment of the
massive black hole in the Galactic Center.Comment: 16 pages, 16 figures, accepted by Ap
The Herschel Virgo Cluster Survey: X.The relationship between cold dust and molecular gas content in Virgo spirals
Using the far-infrared emission, as observed by the Herschel Virgo Cluster
Survey (HeViCS), and the integrated HI and CO brightness, we infer the dust and
total gas mass for a magnitude limited sample of 35 metal rich spiral galaxies
in Virgo. The CO flux correlates tightly and linearly with far-infrared fluxes
observed by Herschel. Molecules in these galaxies are more closely related to
cold dust rather than to dust heated by star formation or to optical/NIR
brightness. We show that dust mass establishes a stronger correlation with the
total gas mass than with the atomic or molecular component alone. The
dust-to-gas ratio increases as the HI deficiency increases, but in highly HI
deficient galaxies it stays constant. Dust is in fact less affected than atomic
gas by weak cluster interactions, which remove most of the HI gas from outer
and high latitudes regions. Highly disturbed galaxies, in a dense cluster
environment, can instead loose a considerable fraction of gas and dust from the
inner regions of the disk keeping constant the dust-to-gas ratio. There is
evidence that the molecular phase is also quenched. This quencing becomes
evident by considering the molecular gas mass per unit stellar mass. Its
amplitude, if confirmed by future studies, highlights that molecules are
missing in Virgo HI deficient spirals, but to a somewhat lesser extent than
dust.Comment: 11 pages, 8 figures. Accepted for publication in A&
Near-infrared proper motions and spectroscopy of infrared excess sources at the Galactic Center
There are a number of faint compact infrared excess sources in the central
stellar cluster of the Milky Way. Their nature and origin is unclear. In
addition to several isolated objects of this kind we find a small but dense
cluster of co-moving sources (IRS13N) about 3" west of SgrA* just 0.5" north of
the bright IRS13E cluster of WR and O-type stars. Based on their color and
brightness, there are two main possibilities: (1) they may be dust embedded
stars older than few Myr, or (2) extremely young, dusty stars with ages less
than 1Myr. We present fist H- and Ks-band identifications or proper motions of
the IRS13N members, the high velocity dusty S-cluster object (DSO), and other
infrared excess sources in the central field. We also present results of NIR H-
and Ks-band ESO-SINFONI integral field spectroscopy of ISR13N. We show that
within the uncertainties, the proper motions of the IRS13N sources in Ks- and
L'-band are identical. This indicates that the bright L'-band IRS13N sources
are indeed dust enshrouded stars rather than core-less dust clouds. The proper
motions show that the IRS13N sources are not strongly gravitationally bound to
each other implying that they have been formed recently. We also present a
first H- and Ks-band identification as well as proper motions and HKsL'-colors
of a fast moving DSO which was recently found in the cluster of high speed
S-stars that surround the super-massive black hole Sagittarius A* (SgrA*). Most
of the compact L'-band excess emission sources have a compact H- or Ks-band
counterpart and therefore are likely stars with dust shells or disks. Our new
results and orbital analysis from our previous work favor the hypothesis that
the infrared excess IRS13N members and other dusty sources close to SgrA* are
very young dusty stars and that star formation at the GC is a continuously
ongoing process.Comment: 20 pages, 18 figures, 4 tables plus appendix with 16 figures and 3
tables accepted by A&
Correlates of extinction risk in squamate reptiles: the relative importance of biology, geography, threat and range size
Aim: Evaluating the relative roles of biological traits and environmental factors that predispose species to an elevated risk of extinction is of fundamental importance to macroecology. Identifying species that possess extinction-promoting traits allows targeted conservation action before precipitous declines occur. Such analyses have been carried out for several vertebrate groups, with the notable exception of reptiles. We identify traits correlating with high extinction risk in squamate reptiles, assess whether these differ with geography, taxonomy and threats, and make recommendations for future Red List assessments. Location: Global. Methods: We collected data on biological traits and environmental factors for a representative sample of 1139 species of squamate reptiles. We used phylogenetically controlled regression models to identify general correlates of extinction risk, threat-specific correlates of risk and realm-specific correlates of risk. We also assessed the relative importance of range size versus other factors through multiplicative bivariate models, partial regressions and variance partitioning. Results: Range size was the most important predictor of extinction risk, reflecting the high frequency of reptiles assessed under range-based IUCN criteria. Habitat specialists occupying accessible ranges were at a greater risk of extinction: although these factors never contributed more than 10% to the variance in extinction risk, they showed significant interactions with range size. The predictive power of our global models ranged from 23% to 29%. The general overall pattern remained the same among geographical, taxonomic and threat-specific data subsets. Main conclusions: Proactive conservation requires shortcuts to identify species at high risk of extinction. Regardless of location, squamate reptiles that are range-restricted habitat specialists living in areas highly accessible to humans are likely to become extinct first. Prioritizing species that exhibit such traits could forestall extinction. Integration of data sources on human pressures, such as accessibility of species ranges, may aid robust and time-efficient assessments of species extinction risk
A gas cloud on its way towards the super-massive black hole in the Galactic Centre
Measurements of stellar orbits provide compelling evidence that the compact
radio source Sagittarius A* at the Galactic Centre is a black hole four million
times the mass of the Sun. With the exception of modest X-ray and infrared
flares, Sgr A* is surprisingly faint, suggesting that the accretion rate and
radiation efficiency near the event horizon are currently very low. Here we
report the presence of a dense gas cloud approximately three times the mass of
Earth that is falling into the accretion zone of Sgr A*. Our observations
tightly constrain the cloud's orbit to be highly eccentric, with an innermost
radius of approach of only ~3,100 times the event horizon that will be reached
in 2013. Over the past three years the cloud has begun to disrupt, probably
mainly through tidal shearing arising from the black hole's gravitational
force. The cloud's dynamic evolution and radiation in the next few years will
probe the properties of the accretion flow and the feeding processes of the
super-massive black hole. The kilo-electronvolt X-ray emission of Sgr A* may
brighten significantly when the cloud reaches pericentre. There may also be a
giant radiation flare several years from now if the cloud breaks up and its
fragments feed gas into the central accretion zone.Comment: in press at Natur
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Larger brain size indirectly increases vulnerability to extinction in mammals
Although previous studies have addressed the question of why large brains evolved, we have limited understanding of potential beneficial or detrimental effects of enlarged brain size in the face of current threats. Using novel phylogenetic path analysis, we evaluated how brain size directly and indirectly, via its effects on life-history and ecology, influences vulnerability to extinction across 474 mammalian species. We found that larger brains, controlling for body size, indirectly increase vulnerability to extinction by extending the gestation period, increasing weaning age, and limiting litter sizes. However, we found no evidence of direct, beneficial or detrimental, effects of brain size on vulnerability to extinction, even when we explicitly considered the different types of threats that lead to vulnerability. Order-specific analyses revealed qualitatively similar patterns for Carnivora and Artiodactyla. Interestingly, for Primates, we found that larger brain size was directly (and indirectly) associated with increased vulnerability to extinction. Our results indicate that under current conditions the constraints on life-history imposed by large brains outweigh the potential benefits, undermining the resilience of the studied mammals. Contrary to the selective forces that have favoured increased brain size throughout evolutionary history, at present, larger brains have become a burden for mammals
Selective Attention Increases Both Gain and Feature Selectivity of the Human Auditory Cortex
Background. An experienced car mechanic can often deduce what’s wrong with a car by carefully listening to the sound of the ailing engine, despite the presence of multiple sources of noise. Indeed, the ability to select task-relevant sounds for awareness, whilst ignoring irrelevant ones, constitutes one of the most fundamental of human faculties, but the underlying neural mechanisms have remained elusive. While most of the literature explains the neural basis of selective attention by means of an increase in neural gain, a number of papers propose enhancement in neural selectivity as an alternative or a complementary mechanism. Methodology/Principal Findings. Here, to address the question whether pure gain increase alone can explain auditory selective attention in humans, we quantified the auditory cortex frequency selectivity in 20 healthy subjects by masking 1000-Hz tones by continuous noise masker with parametrically varying frequency notches around the tone frequency (i.e., a notched-noise masker). The task of the subjects was, in different conditions, to selectively attend to either occasionally occurring slight increments in tone frequency (1020 Hz), tones of slightly longer duration, or ignore the sounds. In line with previous studies, in the ignore condition, the global field power (GFP) of event-related brain responses at 100 ms from the stimulus onset to the 1000-Hz tones was suppressed as a function of the narrowing of the notch width. During the selective attention conditions, the suppressant effect of the noise notch width on GFP was decreased, but as a function significantly different from a multiplicative one expected on the basis of simple gain model of selective attention. Conclusions/Significance. Our results suggest that auditory selective attention in humans cannot be explained by a gai
Development of a video-based education and process change intervention to improve advance cardiopulmonary resuscitation decision-making
Background: Advance cardiopulmonary resuscitation (CPR) decision-making and escalation of care discussions are variable in routine clinical practice. We aimed to explore physician barriers to advance CPR decision-making in an inpatient hospital setting and develop a pragmatic intervention to support clinicians to undertake and document routine advance care planning discussions.
Methods: Two focus groups, which involved eight consultants and ten junior doctors, were conducted following a review of the current literature. A subsequent iterative consensus process developed two intervention elements: (i) an updated ‘Goals of Patient Care’ (GOPC) form and process; (ii) an education video and resources for teaching advance CPR decision-making and communication. A multidisciplinary group of health professionals and policymakers with experience in systems development, education and research provided critical feedback.
Results: Three key themes emerged from the focus groups and the literature, which identified a structure for the intervention: (i) knowing what to say; (ii) knowing how to say it; (iii) wanting to say it. The themes informed the development of a video to provide education about advance CPR decision-making framework, improving communication and contextualising relevant clinical issues. Critical feedback assisted in refining the video and further guided development and evolution of a medical GOPC approach to discussing and recording medical treatment and advance care plans.
Conclusion: Through an iterative process of consultation and review, video-based education and an expanded GOPC form and approach were developed to address physician and systemic barriers to advance CPR decisionmaking and documentation. Implementation and evaluation across hospital settings is required to examine utility and determine effect on quality of care
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