1,623 research outputs found
Investigating pathogen burden in relation to a cumulative deficits index in a representative sample of US adults
Pathogen burden is a construct developed to assess the cumulative effects of multiple, persistent pathogens on morbidity and mortality. Despite the likely biological wear and tear on multiple body systems caused by persistent infections, few studies have examined the impact of total pathogen burden on such outcomes and specifically on preclinical markers of dysfunction. Using data from two waves of the National Health and Nutrition Examination Survey, we compared three alternative methods for measuring pathogen burden, composed of mainly persistent viral infections, using a cumulative deficits index (CDI) as an outcome: single pathogen associations, a pathogen burden summary score and latent class analyses. We found significant heterogeneity in the distribution of the CDI by age, sex, race/ethnicity and education. There was an association between pathogen burden and the CDI by all three metrics. The latent class classification of pathogen burden showed particularly strong associations with the CDI; these associations remained after controlling for age, sex, body mass index, smoking, race/ethnicity and education. Our results suggest that pathogen burden may influence early clinical indicators of poor health as measured by the CDI. Our results are salient since we were able to detect these associations in a relatively young population. These findings suggest that reducing pathogen burden and the specific pathogens that drive the CDI may provide a target for preventing the early development of age-related physiological changes. © 2018 Cambridge University Press
Avoiding Chaos in Wonderland
Wonderland, a compact, integrated economic, demographic and environmental
model is investigated using methods developed for studying critical phenomena.
Simulation results show the parameter space separates into two phases, one of
which contains the property of long term, sustainable development. By employing
information contain in the phase diagram, an optimal strategy involving
pollution taxes is developed as a means of moving a system initially in a
unsustainable region of the phase diagram into a region of sustainability while
ensuring minimal regret with respect to long term economic growth.Comment: 22 pages, 9 figures. Submitted to Physica
Coercive redistribution and public agreement: re-evaluating the libertarian challenge of charity
In this article, we evaluate the capacity of liberal egalitarianism to rebut what we call
the libertarian challenge of charity. This challenge states that coercive redistributive
taxation is neither needed nor justified, since those who endorse redistribution can
give charitably, and those who do not endorse redistribution cannot justifiably be
coerced. We argue that contemporary developments in liberal political thought render
liberalism more vulnerable to this libertarian challenge. Many liberals have, in recent
years, sought to recast liberalism such that it is more hospitable to cultural, religious,
and ethnic diversity. This move has resulted in increased support for the claim that
liberalism should be understood as a political rather than comprehensive doctrine, and
that liberal institutions should draw their legitimacy from agreements made among
members of an appropriately conceived deliberative community, rather than from
controversial liberal principles like individual autonomy. We argue that, while this
move may indeed make liberalism more compatible with cultural diversity, it also
makes it more vulnerable to the libertarian challenge of charity. Not all versions of
liberalism are troubled by the challenge, but those that are troubled by it are
increasingly dominant. We also discuss G. A. Cohen’s claim that liberal equality
requires an ‘egalitarian ethos’ and argue that, if Cohen is right, it is difficult to see
how there can be an adequate response to the libertarian challenge of charity. In
general, our argument can be summarised as follows: the more that liberalism is
concerned accurately to model the actual democratic wishes and motivations of the
people it governs, the less it is able to justify coercively imposing redistributive
principles of justice
ON THE INTRINSIC CHARM COMPONENT OF THE NUCLEON
Using a meson cloud model we calculate the squared charm radius
of the nucleon . The ratio between this squared radius and the ordinary baryon
squared radius is identified with the probability of ``seeing'' the intrinsic
charm component of the nucleon. Our estimate is compatible with those used to
successfully describe the charm production phenomenology.Comment: 9 pages, 2 figures not included, avaiable from the author
Complete next-to-leading order calculation for pion production in nucleon-nucleon collisions at threshold
Based on a counting scheme that explicitly takes into account the large
momentum sqrt(M m_pi) characteristic for pion production in nucleon-nucleon
collisions we calculate all diagrams for the reaction NN --> NN pi at threshold
up to next-to-leading order. At this order there are no free parameters and the
size of the next-to-leading order contributions is in line with the expectation
from power counting. The sum of loop corrections at that order vanishes for the
process pp --> pp pi^0 at threshold. The total contribution at next-to-leading
order from loop diagrams that include the delta degree of freedom vanishes at
threshold in both reaction channels pp --> pp pi^0, pn pi^+.Comment: 9 pages, 4 figure
Nonmonotonic inelastic tunneling spectra due to surface spin excitations in ferromagnetic junctions
The paper addresses inelastic spin-flip tunneling accompanied by surface spin
excitations (magnons) in ferromagnetic junctions. The inelastic tunneling
current is proportional to the magnon density of states which is
energy-independent for the surface waves and, for this reason, cannot account
for the bias-voltage dependence of the observed inelastic tunneling spectra.
This paper shows that the bias-voltage dependence of the tunneling spectra can
arise from the tunneling matrix elements of the electron-magnon interaction.
These matrix elements are derived from the Coulomb exchange interaction using
the itinerant-electron model of magnon-assisted tunneling. The results for the
inelastic tunneling spectra, based on the nonequilibrium Green's function
calculations, are presented for both parallel and antiparallel magnetizations
in the ferromagnetic leads.Comment: 9 pages, 4 figures, version as publishe
Multibeam Maser Survey of methanol and excited OH in the Magellanic clouds: new detections and maser abundance estimates
‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.12888.xPeer reviewe
Higher-order mutual coherence of optical and matter waves
We use an operational approach to discuss ways to measure the higher-order
cross-correlations between optical and matter-wave fields. We pay particular
attention to the fact that atomic fields actually consist of composite
particles that can easily be separated into their basic constituents by a
detection process such as photoionization. In the case of bosonic fields, that
we specifically consider here, this leads to the appearance in the detection
signal of exchange contributions due to both the composite bosonic field and
its individual fermionic constituents. We also show how time-gated counting
schemes allow to isolate specific contributions to the signal, in particular
involving different orderings of the Schr\"odinger and Maxwell fields.Comment: 11 pages, 2 figure
Giant magnetothermopower of magnon-assisted transport in ferromagnetic tunnel junctions
We present a theoretical description of the thermopower due to
magnon-assisted tunneling in a mesoscopic tunnel junction between two
ferromagnetic metals. The thermopower is generated in the course of thermal
equilibration between two baths of magnons, mediated by electrons. For a
junction between two ferromagnets with antiparallel polarizations, the ability
of magnon-assisted tunneling to create thermopower depends on the
difference between the size of the majority and
minority band Fermi surfaces and it is proportional to a temperature dependent
factor where is the magnon Debye
energy. The latter factor reflects the fractional change in the net
magnetization of the reservoirs due to thermal magnons at temperature
(Bloch's law). In contrast, the contribution of magnon-assisted
tunneling to the thermopower of a junction with parallel polarizations is
negligible. As the relative polarizations of ferromagnetic layers can be
manipulated by an external magnetic field, a large difference results in a magnetothermopower effect. This
magnetothermopower effect becomes giant in the extreme case of a junction
between two half-metallic ferromagnets, .Comment: 9 pages, 4 eps figure
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