420 research outputs found
On the Emergent Spectra of Hot Protoplanet Collision Afterglows
We explore the appearance of terrestrial planets in formation by studying the
emergent spectra of hot molten protoplanets during their collisional formation.
While such collisions are rare, the surfaces of these bodies may remain hot at
temperatures of 1000-3000 K for up to millions of years during the epoch of
their formation. These object are luminous enough in the thermal infrared to be
observable with current and next generation optical/IR telescopes, provided
that the atmosphere of the forming planet permits astronomers to observe
brightness temperatures approaching that of the molten surface. Detectability
of a collisional afterglow depends on properties of the planet's atmosphere --
primarily on the mass of the atmosphere. A planet with a thin atmosphere is
more readily detected, because there is little atmosphere to obscure the hot
surface. Paradoxically, a more massive atmosphere prevents one from easily
seeing the hot surface, but also keeps the planet hot for a longer time. In
terms of planetary mass, more massive planets are also easier to detect than
smaller ones because of their larger emitting surface areas. We present
preliminary calculations assuming a range of protoplanet masses (1-10
M_\earth), surface pressures (1-1000 bar), and atmospheric compositions, for
molten planets with surface temperatures ranging from 1000 to 1800 K, in order
to explore the diversity of emergent spectra that are detectable. While current
8- to 10-m class ground-based telescopes may detect hot protoplanets at wide
orbital separations beyond 30 AU (if they exist), we will likely have to wait
for next-generation extremely large telescopes or improved diffraction
suppression techniques to find terrestrial planets in formation within several
AU of their host stars.Comment: 28 pages, 6 figures, ApJ manuscript format, accepted into the Ap
Estimating Small Area Income Deprivation: An Iterative Proportional Fitting Approach
Small area estimation and in particular the estimation of small area income deprivation has
potential value in the development of new or alternative components of multiple deprivation
indices. These new approaches enable the development of income distribution threshold based
as opposed to benefit count based measures of income deprivation and so enable the
alignment of regional and national measures such as the Households Below Average Income
with small area measures. This paper briefly reviews a number of approaches to small area
estimation before describing in some detail an iterative proportional fitting based spatial
microsimulation approach. This approach is then applied to the estimation of small area HBAI
rates at the small area level in Wales in 2003-5. The paper discusses the results of this
approach, contrasts them with contemporary ‘official’ income deprivation measures for the
same areas and describes a range of ways to assess the robustness of the results
smokeSALUD: exploring the effect of demographic change on the smoking prevalence at municipality level in Austria
Background: Reducing the smoking population is still high on the policy agenda, as smoking leads to many preventable diseases, such as lung cancer, heart disease, diabetes, and more. In Austria, data on smoking prevalence only exists at the federal state level. This provides an interesting overview about the current health situation, but for regional planning authorities these data are often insufficient as they can hide pockets of high and low smoking prevalence in certain municipalities. Methods: This paper presents a spatial-temporal change of estimated smokers for municipalities from 2001 and 2011. A synthetic dataset of smokers is built by combining individual large-scale survey data and small area census data using a deterministic spatial microsimulation approach. Statistical analysis, including chi-square test and binary logistic regression, are applied to find the best variables 24 for the simulation model and to validate its results. Results: As no easy-to-use spatial microsimulation software for non-programmers is available yet, a flexible web-based spatial microsimulation application for health decision support (called simSALUD) has been developed and used for these analyses. The results of the simulation show in general a decrease of smoking prevalence within municipalities between 2001 and 2011 and 29 differences within areas are identified. These results are especially valuable to policy decision makers for future planning strategies. Conclusions: This case study shows the application of smokeSALUD to model the spatial-temporal changes in the smoking population in Austria between 2001 and 2011. This is important as no data on smoking exists at this geographical scale (municipality). However, spatial microsimulation models are useful tools to estimate small area health data and to overcome these problems. The simulations and analysis should support health decision makers to identify hot spots of smokers and this should 36 help to show where to spend health resources best in order to reduce health inequalities
Forming new sex partnerships while overseas: findings from the third British national survey of sexual attitudes & lifestyles (Natsal-3)
Objectives: Travelling away from home presents opportunities for new sexual partnerships, which may be associated with sexually transmitted infection (STI) risk. We examined the prevalence of, and factors associated with, reporting new sexual partner(s) while overseas, and whether this differed by partners’ region of residence.
Methods: We analysed data from 12 530 men and women aged 16–74 years reporting ≥1 sexual partner(s) in the past 5 years in Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), a probability survey undertaken 2010–2012.
Results: 9.2% (95% CI 8.3% to 10.1%) of men and 5.3% (4.8% to 5.8%) of women reported new sexual partner(s) while overseas in the past 5 years. This was strongly associated with higher partner numbers and other sexual and health risk behaviours. Among those with new partners while overseas, 72% of men and 58% of women reported partner(s) who were not UK residents. Compared with those having only UK partners while abroad, these people were more likely to identify as ‘White Other’ or ‘Non-White’ (vs White British ethnicity), report higher partner numbers, new partners from outside the UK while in the UK and paying for sex (men only) all in the past 5 years. There was no difference in reporting STI diagnosis/es during this time period.
Conclusions: Reporting new partners while overseas was associated with a range of sexual risk behaviours. Advice on sexual health should be included as part of holistic health advice for all travellers, regardless of age, destination or reason for travel
A primordial atmospheric origin of hydrospheric deuterium enrichment on Mars
The deuterium-to-hydrogen (D/H or 2H/1H) ratio of Martian atmospheric water
(~6x standard mean ocean water, SMOW) is higher than that of known sources,
requiring planetary enrichment. A recent measurement by NASA's Mars Science
Laboratory rover Curiosity of >3 Gyr clays yields a D/H ratio ~3x SMOW,
demonstrating that most enrichment occurs early in Mars's history. As on Venus,
Mars's D/H enrichment is thought to reflect preferential loss to space of 1H
(protium) relative to 2H (deuterium), but the global environmental context of
large and early hydrogen losses remain to be determined. Here, we apply a
recent model of primordial atmosphere evolution to Mars, link the magma ocean
of the accretion epoch with a subsequent water-ocean epoch, and calculate the
behavior of deuterium for comparison with the observed record. We find that a
~2-3x hydrospheric deuterium-enrichment is produced if the Martian magma ocean
is chemically reducing at last equilibration with the primordial atmosphere,
making H2-CO the initially dominant species, with minor abundances of H2O-CO2.
Reducing gases - in particular H2 - can cause greenhouse warming and prevent a
water ocean from freezing immediately after the magma ocean epoch. Moreover,
the pressure-temperature conditions are high enough to produce ocean-atmosphere
H2O-H2 isotopic equilibrium such that surface H2O strongly concentrates
deuterium relative to H2, which preferentially takes up protium and escapes
from the primordial atmosphere. The proposed scenario of primordial H2-rich
outgassing and escape suggests significant durations (>Myr) of chemical
conditions on the Martian surface conducive to prebiotic chemistry immediately
following Martian accretion.Comment: 5 figure
Kids in Communities Study (KiCS) study protocol: a cross-sectional mixed-methods approach to measuring community-level factors influencing early child development in Australia
Introduction: Healthy childhood development in the early years is critical for later adult health and well-being. Early childhood development (ECD) research has focused primarily on individual, family and school factors, but largely ignored community factors. The Kids in Communities Study (KiCS) will test and investigate community-level influences on child development across Australia. Methods and analysis: Cross-sectional mixed-methods study exploring community-level effects in 25 Australian local communities; selection based on community socioeconomic status (SES) and ECD using the Australian Early Development Census (AEDC), a population measure of child development, to create a local community 'diagonality type', that is, those performing better or worse (off-diagonal), or as expected (on-diagonal) on the AEDC relative to their SES. Data collection includes stakeholder interviews, parent and service provider focus groups, and surveys with general community residents and service providers, mapping of neighbourhood design and local amenities and services, analysis of policy documents, and the use of existing sociodemographic and early childhood education and care data. Quantitative data will be used to test associations between local community diagonality type, and ECD based on AEDC scores. Qualitative data will provide complementary and deeper exploration of these same associations. Ethics and dissemination: The Royal Children's Hospital Human Research Ethics Committee approved the study protocol (#30016). Further ethics approvals were obtained from State Education and Health departments and Catholic archdioceses where required. ECD community-level indicators will eventually be derived and made publically available. Findings will be published in peer-reviewed journals, community reports, websites and policy briefs to disseminate results to researchers, and key stakeholders including policymakers, practitioners and (most importantly) the communities involved.Sharon Goldfeld, Karen Villanueva, Robert Tanton, Ilan Katz, Sally Brinkman, Geoffrey Woolcock, Billie Giles-Cort
Why Do Men Report More Opposite-Sex Sexual Partners Than Women? Analysis of the Gender Discrepancy in a British National Probability Survey.
In a closed population and defined time period, the mean number of opposite-sex partners reported by men and women should be equal. However, in all surveys, men report more partners. This inconsistency is pivotal to debate about the reliability of self-reported sexual behavior. We used data from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3), a probability sample survey of the British population, to investigate the extent to which survey sampling, accounting strategies (e.g., estimating versus counting), and (mis)reporting due to social norms might explain the inconsistency. Men reported a mean of 14.14 lifetime partners; women reported 7.12. The gender gap of 7.02 reduced to 5.47 after capping the lifetime partner number at the 99th percentile. In addition, adjusting for counting versus estimation reduced the gender gap to 3.24, and further adjusting for sexual attitudes narrowed it to 2.63. Together, these may account for almost two-thirds of the gender disparity. Sampling explanations (e.g., non-U.K.-resident partners included in counts; sex workers underrepresented) had modest effects. The findings underscore the need for survey methods that facilitate candid reporting and suggest that approaches to encourage counting rather than estimating may be helpful. This study is novel in interrogating a range of potential explanations within the same nationally representative data set
Heterosexual Practices Among Young People in Britain: Evidence From Three National Surveys of Sexual Attitudes and Lifestyles.
PURPOSE: To describe time trends and current patterns in sexual practices with opposite-sex partners among men and women aged 16-24 years in Britain. METHODS: Complex survey analyses of cross-sectional probability survey data from three British National Surveys of Sexual Attitudes and Lifestyles (Natsal), conducted approximately decennially 1990-2012, involving interviews with 45,199 people in total. RESULTS: Birth cohort analysis showed a decline in the median age at first sexual experience and first intercourse since the midtwentieth century and a narrowing of the interval between these events. Comparison of data from Natsals 1, 2, and 3 showed increases in the prevalence of ever experience of oral and anal sex among 16- to 24-year-olds, which were more marked among older respondents in this age group between Natsals 1 and 2, and among younger respondents between Natsals 2 and 3. Among the sexually active, vaginal and oral sex remained the most common combination of practices reported in the past year. The proportion reporting a past-year repertoire of vaginal, oral, and anal sex rose from approximately one in 10 in 1990-1991 to approximately one in four men and one in five women in 2010-2012. In the latest survey, heterosexual experience of practices was positively associated with bisexual attraction among women. CONCLUSIONS: Recent decades have seen an earlier age at initiation of partnered sexual experiences and increased diversity in heterosexual practices among young people. Keeping pace with trends in sexual practices is necessary to safeguard young people's health and to support them in increasing their sexual well-being
A global optimisation approach to range-restricted survey calibration
Survey calibration methods modify minimally unit-level sample weights to fit domain-level benchmark constraints (BC). This allows exploitation of auxiliary information, e.g. census totals, to improve the representativeness of sample data (addressing coverage limitations, non-response) and the quality of estimates of population parameters. Calibration methods may fail with samples presenting small/zero counts for some benchmark groups or when range restrictions (RR), such as positivity, are imposed to avoid unrealistic or extreme weights. User-defined modifications of BC/RR performed after encountering non-convergence allow little control on the solution, and penalization approaches modelling infeasibility may not guarantee convergence. Paradoxically, this has led to underuse in calibration of highly disaggregated information, when available. We present an always-convergent flexible two-step Global Optimisation (GO) survey calibration approach. The feasibility of the calibration problem is assessed, and automatically controlled minimum errors in BC or changes in RR are allowed to guarantee convergence in advance, while preserving the good properties of calibration estimators. Modelling alternatives under different scenarios, using various error/change and distance measures are formulated and discussed. The GO approach is validated by calibrating the weights of the 2012 Health Survey for England to a fine age-gender-region cross-tabulation (378 counts) from the 2011 Census in England and Wales
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