1,622 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
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Fully Depleted, Monolithic Pinned Photodiode CMOS Image Sensor Using Reverse Substrate Bias
A new pixel design using pinned photodiode (PPD) in a 180 nm CMOS image sensor (CIS) process has been developed as a proof of principle. The sensor can be fully depleted by means of reverse bias applied to the substrate, and the principle of operation is applicable to very thick sensitive volumes. Additional n-type implants under the in-pixel p-wells have been added to the manufacturing process in order to eliminate the large parasitic substrate current that would otherwise be present in a normal device. The new design exhibits nearly identical electro-optical performance under reverse bias as the reference PPD pixel it is based on, and the leakage current is effectively suppressed. The characterisation results from both front- and back-side illuminated sensor variants show that the epitaxial layer is fully depleted
AN INTRODUCTION TO SPATIAL MODELING IN FISHERIES ECONOMICS
Resource /Energy Economics and Policy,
29 years of vegetation community change across environmental gradients in a Mojave Desert mountain range
There is a great deal of uncertainty as to how biological communities respond to changes in land use and climate change, a situation particularly relevant in protected areas such as national parks that were designated to conserve specific biological features. Utilizing extant vegetation data sets with repeatable methodology can provide opportunities for insight into previous vegetation change and provide base line data for long-term monitoring projects useful for modeling vegetation community trajectories. We have relocated and resurveyed 106 sites from a vegetation community study initiated in 1979 in the Newberry Mountains, southern Nevada, within Lake Mead National Recreation Area managed by the National Park Service. The original methods were repeated and used to establish permanent long-term monitoring plots. All perennial plant species were measured for density, frequency and cover within each plot. In comparing 1979 and 2008 data sets we wanted to know if changes have occurred in the vegetation community and if the degree of change differs along environmental gradients and among individual species
A hemispheric study of weather types
http://hdl.handle.net/10945/14243http://www.archive.org/details/hemisphericstudy00hollU.S. Navy (U.S.N.) author.U.S. Marine Corps (U.S.M.C.) author
Impact of Neutron Energy on Asteroid Deflection Performance
In the future, a hazardous asteroid will find itself on a collision course with Earth. For asteroids of moderate size or larger, a nuclear device is one of humanity\u27s only technologies capable of mitigating this threat via deflection on a timescale of less than a decade. This work examined how the output neutron energy from a nuclear device standoff detonation affects the deflection of a notional asteroid that is 300 meters in diameter and composed of silicon dioxide at a bulk density of 1.855 g/cm3. 14.1 MeV and 1 MeV neutron energy sources were modeled in MCNP to quantify the energy deposition in the asteroid target. The asteroid\u27s irradiated region was discretized in angle by tracing the rays emanating from the point of detonation and in depth by considering the neutron mean-free-paths. This high-fidelity approach was shown to deviate from previous analytic approximations commonly used for asteroid energy deposition. 50 kt and 1 Mt neutron yields of the energy deposition mappings were imported into a hydrodynamic asteroid model in ALE3D to simulate the deflective response due to blow-off ejecta. Underexplored in literature, changing the neutron energy was found to have up to a 70% impact on deflection performance due to induced differences in the energy deposition profile and in the energy coupling efficiency. The magnitude of energy deposition accounted for most of the observed variation in the asteroid velocity change, making the coupling efficiency more significant than the spatial profile characteristics. These findings are vital for determining the optimal source neutron energy spectrum for asteroid deflection applications
Dust emissivity in the Submm/Mm: SCUBA and SIMBA observations of Barnard 68
We have observed the dark cloud Barnard 68 with SCUBA at 850 um and with
SIMBA at 1.2 mm. The submillimetre and millimetre dust emission correlate well
with the extinction map of Alves, Lada and Lada (2001).The A_V/850um
correlation is clearly not linear and suggests lower temperatures for the dust
in the inner core of the cloud. Assuming a model for the temperature gradient,
we derive the cloud-averaged dust emissivities (normalised to the V-Band
extinction efficiency) at 850 um and 1.2 mm. We find k_850um/k_V = 4.0 +/- 1.0
x 10^-5 and k_1.2mm/k_V = 9.0 +/- 3.0 x 10^-6. These values are compared with
other determinations in this wavelength regime and with expectations for models
of diffuse dust and grain growth in dense clouds.Comment: 8 pages, 4 figures, A&A accepted (Letter), referee forma
The Ursinus Weekly, March 20, 1969
Board appoints Gold new Weekly editor • Campus Chest to support Melmark Home and Biafra • College names Alumni Director • USGA discusses drinking; Punishment system needed • College counselors Admissions Center offer students aid • Editors\u27 farewell • Letters to the editor • Conscription not the answer; Voluntary service best solution • Miss Cope enthusiastic about Ursinus challenge • From the Hofstra Chronicle • USGA notes • Womens Club plans annual card party • Emig, Novak lead USGA in new council plan • UC student recalls trials, joys of European travel • YM-YWCA officers emphasize civic aid • $500,000 grant for science building awarded to Ursinus • New building to house administrative offices • Williamson and Davis head travel courses • Batsmen begin practice, JV tennis inaugurated • Athletes named for track awards • Dennis recalls his 1930 southern trip • Schwenkler leads UC in swimming finals • Gillespie makes all area squad • Arts Festival \u2769: A reviewhttps://digitalcommons.ursinus.edu/weekly/1172/thumbnail.jp
Mojave Applied Ecology Notes Spring 2011
Red brome distribution in the eastern Mojave Desert, A look at the UNLV xeric gardens and Marjorie Barrick museum, Summary of recent science synthesis effort
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