13,003 research outputs found
On "Sexual contacts and epidemic thresholds," models and inference for Sexual partnership distributions
Recent work has focused attention on statistical inference for the population
distribution of the number of sexual partners based on survey data.
The characteristics of these distributions are of interest as components of
mathematical models for the transmission dynamics of sexually-transmitted
diseases (STDs). Such information can be used both to calibrate theoretical
models, to make predictions for real populations, and as a tool for guiding
public health policy.
Our previous work on this subject has developed likelihood-based statistical
methods for inference that allow for low-dimensional, semi-parametric models.
Inference has been based on several proposed stochastic process models for the
formation of sexual partnership networks. We have also developed model
selection criteria to choose between competing models, and assessed the fit of
different models to three populations: Uganda, Sweden, and the USA. Throughout
this work, we have emphasized the correct assessment of the uncertainty of the
estimates based on the data analyzed. We have also widened the question of
interest to the limitations of inferences from such data, and the utility of
degree-based epidemiological models more generally.
In this paper we address further statistical issues that are important in
this area, and a number of confusions that have arisen in interpreting our
work. In particular, we consider the use of cumulative lifetime partner
distributions, heaping and other issues raised by Liljeros et al. in a recent
working paper.Comment: 22 pages, 5 figures in linked working pape
Clinical alcohol guidelines are welcome—but upstream action is paramount
Letter to the edito
The English are healthier than the Americans: really?
Background: When comparing the health of two populations, it is not enough to compare the prevalence of chronic diseases. The objective of this study is therefore to propose a metric of health based on domains of functioning to determine whether the English are healthier than the Americans. Methods: We analysed representative samples aged 50 to 80 years from the 2008 wave of the Health and Retirement Study (N?=?10?349) for the US data, and wave 4 of the English Longitudinal Study of Ageing (N?=?9405) for English counterpart data. We first calculated the age-standardized disease prevalence of diabetes, hypertension, all heart diseases, stroke, lung disease, cancer and obesity. Second, we developed a metric of health using Rasch analyses and the questions and measured tests common to both surveys addressing domains of human functioning. Finally, we used a linear additive model to test whether the differences in health were due to being English or American. Results: The English have better health than the Americans when population health is assessed only by prevalence of selected chronic health conditions. The English health advantage disappears almost completely, however, when health is assessed with a metric that integrates information about functioning domains. Conclusions: It is possible to construct a metric of health, based on data directly collected from individuals, in which health is operationalized as domains of functioning. Its application has the potential to tackle one of the most intractable problems in international research on health, namely the comparability of health across countries
Neisseria meningitidis serogroup C sepsis and septic arthritis in an HIV-positive man
A patient with well-controlled HIV-1 infection presented with fever and rigors, a widespread maculopapular rash, and severe generalised arthralgia. Sepsis of unknown aetiology was diagnosed, and treatment with broad-spectrum antimicrobials commenced. Following initial clinical improvement, a right knee septic arthritis developed. Microscopy and culture of the joint aspirate were negative for organisms but 16S rDNA PCR identified Neisseria meningitidis DNA, subsequently verified as capsular genogroup C, thus confirming a diagnosis of disseminated meningococcal sepsis with secondary septic arthritis
Problems with Fitting to the Power-Law Distribution
This short communication uses a simple experiment to show that fitting to a
power law distribution by using graphical methods based on linear fit on the
log-log scale is biased and inaccurate. It shows that using maximum likelihood
estimation (MLE) is far more robust. Finally, it presents a new table for
performing the Kolmogorov-Smirnof test for goodness-of-fit tailored to
power-law distributions in which the power-law exponent is estimated using MLE.
The techniques presented here will advance the application of complex network
theory by allowing reliable estimation of power-law models from data and
further allowing quantitative assessment of goodness-of-fit of proposed
power-law models to empirical data.Comment: 4 pages, 1 figure, 2 table
Polarisation Observations of HO 620.701 GHz Maser Emission with Herschel/HIFI in Orion KL
Context. The high intensities and narrow bandwidths exhibited by some
astronomical masers make them ideal tools for studying star-forming giant
molecular clouds. The water maser transition at
620.701 GHz can only be observed from above Earth's strongly absorbing
atmosphere; its emission has recently been detected from space. Aims. We sought
to further characterize the star-forming environment of Orion KL by
investigating the linear polarisation of a source emitting a narrow 620.701 GHz
maser feature with the heterodyne spectrometer HIFI on board the Herschel Space
Observatory. Methods. High-resolution spectral datasets were collected over a
thirteen month period beginning in 2011 March, to establish not only the linear
polarisation but also the temporal variability of the source. Results. Within a
uncertainty, no polarisation was detected to an upper limit of
approximately 2%. These results are compared with coeval linear polarisation
measurements of the 22.235 GHz maser line from
the Effelsberg 100-m radio telescope, typically a much stronger maser
transition. Although strongly polarised emission is observed for one component
of the 22.235 GHz maser at 7.2 km s, a weaker component at the same
velocity as the 620.701 GHz maser at 11.7 km s is much less polarised.Comment: Accepted for publication in A&
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