27,005 research outputs found
Pioneer 10 Jupiter atmospheric definition results: A summary
The various entry probes for measuring outer planetary atmospheric compositions are discussed. Considered are chemical components and physical accumulation processes observable by spectroscopic studies, as well as pressure gauges, temperature gauges, accelerometers, nephelometers, and visible and infrared sensors for determining abundances
Understanding Physical Conditions in High Redshift Galaxies through C I Fine Structure Lines: Data and Methodology
We probe the physical conditions in high redshift galaxies, specifically, the
Damped Lyman-alpha Systems (DLAs) using neutral carbon (CI) fine structure
lines and molecular hydrogen (H2). We report five new detections of CI and
analyze the CI in an additional 2 DLAs with previously published data. We also
present one new detection of H2 in a DLA. We present a new method of analysis
that simultaneously constrains \emph{both} the volume density and the
temperature of the gas, as opposed to previous studies that a priori assumed a
gas temperature. We use only the column density of CI measured in the fine
structure states and the assumption of ionization equilibrium in order to
constrain the physical conditions in the gas. We present a sample of 11 CI
velocity components in 6 DLAs and compare their properties to those derived by
the global CII* technique. The resulting median values for this sample are:
= 69 cm^{-3}, = 50 K, and = 3.86 cm^{-3} K, with
standard deviations, sigma_{n(HI)} = 134 cm^{-3}, sigma_T = 52 K, and
sigma_{log(P/k)} = 3.68 cm^{-3} K. This can be compared with the integrated
median values for the same DLAs : = 2.8 cm^{-3}, = 139 K, and
= 2.57 cm^{-3} K, with standard deviations sigma_{n(HI)} = 3.0
cm^{-3}, sigma_T = 43 K, and sigma_{log(P/k)} = 0.22 cm^{-3} K. Interestingly,
the pressures measured in these high redshift CI clouds are similar to those
found in the Milky Way. We conclude that the CI gas is tracing a
higher-density, higher-pressure region, possibly indicative of post-shock gas
or a photodissociation region on the edge of a molecular cloud. We speculate
that these clouds may be direct probes of the precursor sites of star formation
in normal galaxies at high redshift.Comment: Accepted for publication in Ap
Target absent trials in configural contextual cuing
In contextual cueing (CC), reaction times to find targets in repeated displays are faster than in displays that have never been seen before. This has been demonstrated using target-distractor configurations, global background colors, naturalistic scenes and the co-variation of target with distractors. The majority of CC studies have used displays where the target is always present. This paper investigates what happens when the target is sometimes absent. Experiment 1 shows that, although configural CC occurs in displays when the target is always present, there is no CC when the target is always absent. Experiment 2 shows that there is no CC when the same spatial layout can be both target present and target absent on different trials. The presence of distractors in locations that contain targets on other trials appears to interfere with CC and even disrupts the expression of previously learned contexts (Experiments 3-5). The results show that it is the target-distractor associations that are important in producing CC and, consistent with a response selection account, changing the response type from an orientation task to a detection task removes the CC effect
Inequality and Health: Is Housing Crowding the Link?
In this study we extend the literature (e.g. Deaton, 2002a; Kennedy and Kawachi, 1996; Wilkinson, 1996) by proposing a new mechanism through which income inequality can influence health. We argue that increased income inequality induces household crowding, which in turn leads to increased rates of infectious diseases. We use data from New Zealand that links hospital discharge rates with community-level characteristics to explore this hypothesis. Our results provide support for a differential effect of income inequality and housing crowding on rates of hospital admissions for infectious diseases among children. Importantly, we find that genetic and non-communicable diseases do not show these joint crowding and inequality effects. The effect of housing on communicable diseases provides a biological foundation for an income inequality gradient.Housing crowding, child health outcomes, income inequality
The relationship between EQ-5D, HAQ and pain in patients with rheumatoid arthritis: further validation and development of the limited dependent variable, mixture model approach
Objective
To provide robust estimates of EQ-5D as a function of the Health Assessment Questionnaire
(HAQ) and pain in patients with rheumatoid arthritis.
Method
Repeated observations of patients diagnosed with RA in a US observational cohort (n=100,398 observations) who provided data on HAQ, pain on a visual analogue scale and the EQ-5D questionnaire. We use a bespoke mixture modelling approach to appropriately reflect the characteristics of the EQ-5D instrument and compare this to results from linear regression.
Results
The addition of pain alongside HAQ as an explanatory variable substantially improves explanatory power. The preferred model is a four component mixture. Unlike the linear regression it exhibits very good fit to the data, does not suffer from problems of bias or predict values outside the feasible range.
Conclusions
It is appropriate to model the relationship between HAQ and EQ-5D but only if suitable statistical methods are applied. Linear models underestimate the QALY benefits, and therefore the cost effectiveness, of therapies. The bespoke mixture model approach outlined here overcomes this problem. The addition of pain as an explanatory variable greatly improves the estimates
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