9,038 research outputs found
Conditional survival with increasing duration of ICU admission: an observational study of three intensive care databases.
OBJECTIVES: Prolonged admissions to an ICU are associated with high resource utilization and personal cost to the patient. Previous reports suggest increasing length of stay may be associated with poor outcomes. Conditional survival represents the probability of future survival after a defined period of treatment on an ICU providing a description of how prognosis evolves over time. Our objective was to describe conditional survival as length of ICU stay increased. DESIGN: Retrospective observational cohort study of three large intensive care databases. SETTING: Three intensive care databases, two in the United States (Medical Information Mart for Intensive Care III and electronic ICU) and one in United Kingdom (Post Intensive Care Risk-Adjusted Alerting and Monitoring). PATIENTS: Index admissions to intensive care for patients 18 years or older. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 11,648, 38,532, and 165,125 index admissions were analyzed from Post Intensive Care Risk-Adjusted Alerting and Monitoring, Medical Information Mart for Intensive Care III and electronic ICU databases respectively. In all three cohorts, conditional survival declined over the first 5-10 days after ICU admission and changed little thereafter. In patients greater than or equal to 75 years old conditional survival continued to decline with increasing length of stay. CONCLUSIONS: After an initial period of 5-10 days, probability of future survival does not appear to decrease with increasing length of stay in unselected patients admitted to ICUs in United Kingdom and United States [corrected]. These findings were consistent between the three populations and suggest that a prolonged admission to an ICU is not a reason for a pessimism in younger patients but may indicate a poor prognosis in the older population
Plasma electrons above Saturn's main rings: CAPS observations
We present observations of thermal ( similar to 0.6 - 100eV) electrons observed near Saturn's main rings during Cassini's Saturn Orbit Insertion (SOI) on 1 July 2004. We find that the intensity of electrons is broadly anticorrelated with the ring optical depth at the magnetic footprint of the field line joining the spacecraft to the rings. We see enhancements corresponding to the Cassini division and Encke gap. We suggest that some of the electrons are generated by photoemission from ring particle surfaces on the illuminated side of the rings, the far side from the spacecraft. Structure in the energy spectrum over the Cassini division and A-ring may be related to photoelectron emission followed by acceleration, or, more likely, due to photoelectron production in the ring atmosphere or ionosphere
A massive reservoir of low-excitation molecular gas at high redshift
Molecular hydrogen is an important component of galaxies because it fuels
star formation and accretion onto AGN, the two processes that generate the
large infrared luminosities of gas-rich galaxies. Observations of spectral-line
emission from the tracer molecule CO are used to probe the properties of this
gas. But the lines that have been studied in the local Universe, mostly the
lower rotational transitions of J = 1-0 and J = 2-1, have hitherto been
unobservable in high-redshift galaxies. Instead, higher transitions have been
used, although the densities and temperatures required to excite these higher
transitions may not be reached by much of the gas. As a result, past
observations may have underestimated the total amount of molecular gas by a
substantial amount. Here we report the discovery of large amounts of
low-excitation molecular gas around the infrared-luminous quasar, APM
08279+5255 at z = 3.91, using the two lowest excitation lines of 12CO (J = 1-0
and J = 2-1). The maps confirm the presence of hot and dense gas near the
nucleus, and reveal an extended reservoir of molecular gas with low excitation
that is 10 to 100 times more massive than the gas traced by higher-excitation
observations. This raises the possibility that significant amounts of
low-excitation molecular gas may lurk in the environments of high-redshift (z >
3) galaxies.Comment: To appear as a Letter to Nature, 4th January 200
The glyoxal budget and its contribution to organic aerosol for Los Angeles, California, during CalNex 2010
Recent laboratory and field studies have indicated that glyoxal is a potentially large contributor to secondary organic aerosol mass. We present in situ glyoxal measurements acquired with a recently developed, high sensitivity spectroscopic instrument during the CalNex 2010 field campaign in Pasadena, California. We use three methods to quantify the production and loss of glyoxal in Los Angeles and its contribution to organic aerosol. First, we calculate the difference between steady state sources and sinks of glyoxal at the Pasadena site, assuming that the remainder is available for aerosol uptake. Second, we use the Master Chemical Mechanism to construct a two-dimensional model for gas-phase glyoxal chemistry in Los Angeles, assuming that the difference between the modeled and measured glyoxal concentration is available for aerosol uptake. Third, we examine the nighttime loss of glyoxal in the absence of its photochemical sources and sinks. Using these methods we constrain the glyoxal loss to aerosol to be 0-5 × 10-5 s-1 during clear days and (1 ± 0.3) × 10-5 s-1 at night. Between 07:00-15:00 local time, the diurnally averaged secondary organic aerosol mass increases from 3.2 μg m-3 to a maximum of 8.8 μg m -3. The constraints on the glyoxal budget from this analysis indicate that it contributes 0-0.2 μg m-3 or 0-4% of the secondary organic aerosol mass. Copyright 2011 by the American Geophysical Union
First anatomical network analysis of fore- and hindlimb musculoskeletal modularity in bonobos, common chimpanzees, and humans
Studies of morphological integration and modularity, and of anatomical complexity in human evolution typically focus on skeletal tissues. Here we provide the first network analysis of the musculoskeletal anatomy of both the fore- and hindlimbs of the two species of chimpanzee and humans. Contra long-accepted ideas, network analysis reveals that the hindlimb displays a pattern opposite to that of the forelimb: Pan big toe is typically seen as more independently mobile, but humans are actually the ones that have a separate module exclusively related to its movements. Different fore- vs hindlimb patterns are also seen for anatomical network complexity (i.e., complexity in the arrangement of bones and muscles). For instance, the human hindlimb is as complex as that of chimpanzees but the human forelimb is less complex than in Pan. Importantly, in contrast to the analysis of morphological integration using morphometric approaches, network analyses do not support the prediction that forelimb and hindlimb are more dissimilar in species with functionally divergent limbs such as bipedal humans
The inevitable youthfulness of known high-redshift radio galaxies
Radio galaxies can be seen out to very high redshifts, where in principle
they can serve as probes of the early evolution of the Universe. Here we show
that for any model of radio-galaxy evolution in which the luminosity decreases
with time after an initial rapid increase (that is, essentially all reasonable
models), all observable high-redshift radio-galaxies must be seen when the
lobes are less than 10^7 years old. This means that high-redshift radio
galaxies can be used as a high-time-resolution probe of evolution in the early
Universe. Moreover, this result helps to explain many observed trends of
radio-galaxy properties with redshift [(i) the `alignment effect' of optical
emission along radio-jet axes, (ii) the increased distortion in radio
structure, (iii) the decrease in physical sizes, (iv) the increase in radio
depolarisation, and (v) the increase in dust emission] without needing to
invoke explanations based on cosmology or strong evolution of the surrounding
intergalactic medium with cosmic time, thereby avoiding conflict with current
theories of structure formation.Comment: To appear in Nature. 4 pages, 2 colour figures available on request.
Also available at http://www-astro.physics.ox.ac.uk/~km
Prevalence of adult ADHD in an all-female prison unit.
There is increasing evidence suggesting a link between ADHD and criminality, including a strong association between ADHD symptoms and the likelihood of being on probation or in prison. Most studies investigating the prevalence of ADHD in prison populations have focused on adult male offenders. In the current study, 69 female prisoners were screened for both childhood and adult ADHD symptoms using the Barkley Adult ADHD Rating Scale-IV. The results indicate that 41 % of the prisoners met the diagnostic criteria for ADHD in childhood and continued to meet criteria for ADHD as adults. More importantly, young female prisoners (aged 18-25) were significantly more likely to report symptoms of ADHD than older prisoners. Prisoners who reported symptoms of ADHD also reported high levels of impairment associated with these symptoms. A better understanding of the prevalence of ADHD in female prison units can highlight specific areas for intervention during rehabilitation, as well as the management of serious incidents within prison
Generalized quark-antiquark potential at weak and strong coupling
We study a two-parameter family of Wilson loop operators in N=4
supersymmetric Yang-Mills theory which interpolates smoothly between the 1/2
BPS line or circle and a pair of antiparallel lines. These observables capture
a natural generalization of the quark-antiquark potential. We calculate these
loops on the gauge theory side to second order in perturbation theory and in a
semiclassical expansion in string theory to one-loop order. The resulting
determinants are given in integral form and can be evaluated numerically for
general values of the parameters or analytically in a systematic expansion
around the 1/2 BPS configuration. We comment about the feasibility of deriving
all-loop results for these Wilson loops.Comment: 43 pages: 15 comprising the main text and 25 for detailed appendice
Holographic three-point functions of giant gravitons
Working within the AdS/CFT correspondence we calculate the three-point
function of two giant gravitons and one pointlike graviton using methods of
semiclassical string theory and considering both the case where the giant
gravitons wrap an S^3 in S^5 and the case where the giant gravitons wrap an S^3
in AdS_5. We likewise calculate the correlation function in N=4 SYM using two
Schur polynomials and a single trace chiral primary. We find that the gauge and
string theory results have structural similarities but do not match perfectly,
and interpret this in terms of the Schur polynomials' inability to interpolate
between dual giant and pointlike gravitons.Comment: 21 page
On the Schoenberg Transformations in Data Analysis: Theory and Illustrations
The class of Schoenberg transformations, embedding Euclidean distances into
higher dimensional Euclidean spaces, is presented, and derived from theorems on
positive definite and conditionally negative definite matrices. Original
results on the arc lengths, angles and curvature of the transformations are
proposed, and visualized on artificial data sets by classical multidimensional
scaling. A simple distance-based discriminant algorithm illustrates the theory,
intimately connected to the Gaussian kernels of Machine Learning
- …