352 research outputs found
SARS-CoV-2/COVID-19 vaccines: The promises and the challenges ahead
: The development of a new vaccine usually consists of a linear sequence of several steps and lasts many years [...]
Disability, Work and Cash Benefits
This book examines the economic consequences of work disabilities, and public and private interventions that might enable disabled individuals to enter the work force for the first time, remain at work, or return to work. Three groups of papers are presented. The first group examines ways that labor market changes, policy interventions and individual choices shape the work force. The next analyzes both public and private return to work policies for the work disabled and for those with a severely disabling condition. The final group focuses on the specific needs of the disabled that affect their work force participation, including access to health care, personal assistance and assistive technologies.https://research.upjohn.org/up_press/1195/thumbnail.jp
Top-down cascading effects driven by the odontocetes in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)
An investigation of the marine food web in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) was carried out to explore the top-down cascading effects driven by the Odontocetes. The food web was analysed by a mass-balance model using 51 functional groups and detailing the trophic impacts of the striped and common bottlenose dolphins, the Risso's dolphin and the sperm whale during the period 2010-2014. Odontocetes resulted top-predators with the highest TL estimated for the Risso's dolphin (TL=5.40) and the lowest for the common bottlenose dolphin (TL=4.47). The striped dolphin played the highest top-down control, showing cascading effects up to the 3rd TL. The Risso's dolphin and the sperm whale played similar cascading effects, but weaker than the striped dolphin. Understanding pattern and strengthen of trophic controls played by the Odontocetes within the food web could contribute to identify the basal mechanisms involved in the ecosystem functioning
Prompt neutrino fluxes from atmospheric charm
We calculate the prompt neutrino flux from atmospheric charm production by
cosmic rays, using the dipole picture in a perturbative QCD framework, which
incorporates the parton saturation effects present at high energies. We compare
our results with the next-to-leading order perturbative QCD result and find
that saturation effects are large for neutrino energies above 10^6 GeV, leading
to a substantial suppression of the prompt neutrino flux. We comment on the
range of prompt neutrino fluxes due to theoretical uncertainties.Comment: 13 pages with 11 figures; expanded discussion, added references,
version to be published in Phys. Rev.
Radio Detection of High Energy Particles: Coherence Versus Multiple Scales
Radio Cherenkov emission underlines detection of high energy particles via a
signal growing like the particle-energy-squared. Cosmic ray-induced
electromagnetic showers are a primary application. While many studies have
treated the phenomenon approximately, none have attempted to incorporate all
the physical scales involved in problems with time- or spatially- evolving
charges. We find it is possible to decompose the calculated fields into the
product of a form factor, characterizing a moving charge distribution,
multiplying a general integral which depends on the charge evolution. In
circumstances of interest for cosmic ray physics, the resulting expressions can
be evaluated explicitely in terms of a few parameters obtainable from shower
codes. The classic issues of Frauhofer and Fresnel zones play a crucial role in
the coherence.Comment: 25 pages, 10 figure
Lepton Fluxes from Atmospheric Charm
We reexamine the charm contribution to atmospheric lepton fluxes in the
context of perturbative QCD. We include next-to-leading order corrections and
discuss theoretical uncertainties due to the extrapolations of the gluon
distributions at small-x. We show that the charm contribution to the
atmospheric muon flux becomes dominant over the conventional contribution from
pion and kaon decays at energies of about 10^5 GeV. We compare our fluxes with
previous calculations.Comment: 19 pages, latex, revtex, psfi
Hadron collider limits on anomalous couplings
A next-to-leading log calculation of the reactions and
is presented including a tri-boson
gauge coupling from non-Standard Model contributions. Two approaches are made
for comparison. The first approach considers the tri-boson coupling
as being uniquely fixed by tree level unitarity at high energies to its
Standard Model form and, consequently, suppresses the non-Standard Model
contributions with form factors. The second approach is to ignore such
considerations and calculate the contributions to non-Standard Model tri-boson
gauge couplings without such suppressions. It is found that at Tevatron
energies, the two approaches do not differ much in quantitative results, while
at Large Hadron Collider (LHC) energies the two approaches give significantly
different predictions for production rates. At the Tevatron and LHC, however,
the sensitivity limits on the anomalous coupling of are too weak to
usefully constrain parameters in effective Lagrangian models.Comment: Revtex 23 pages + 8 figures, UIOWA-94-1
Neutrino Interactions at Ultrahigh Energies
We report new calculations of the cross sections for deeply inelastic
neutrino-nucleon scattering at neutrino energies between 10^{9}\ev and
10^{21}\ev. We compare with results in the literature and assess the
reliability of our predictions. For completeness, we briefly review the cross
sections for neutrino interactions with atomic electrons, emphasizing the role
of the -boson resonance in interactions for neutrino
energies in the neighborhood of 6.3\pev. Adopting model predictions for
extraterrestrial neutrino fluxes from active galactic nuclei, gamma-ray
bursters, and the collapse of topological defects, we estimate event rates in
large-volume water \v{C}erenkov detectors and large-area ground arrays.Comment: 32 pages, 11 figures, uses RevTeX and boxedep
Electromagnetic Cascades and Cascade Nucleosynthesis in the Early Universe
We describe a calculation of electromagnetic cascading in radiation and
matter in the early universe initiated by the decay of massive particles or by
some other process. We have used a combination of Monte Carlo and numerical
techniques which enables us to use exact cross sections, where known, for all
the relevant processes. In cascades initiated after the epoch of big bang
nucleosynthesis -rays in the cascades will photodisintegrate He,
producing He and deuterium. Using the observed He and deuterium
abundances we are able to place constraints on the cascade energy deposition as
a function of cosmic time. In the case of the decay of massive primordial
particles, we place limits on the density of massive primordial particles as a
function of their mean decay time, and on the expected intensity of decay
neutrinos.Comment: compressed and uuencoded postscript. We now include a comparison with
previous work of the photon spectrum in the cascade and the limits we
calculate for the density of massive particles. The method of calculation of
photon spectra at low energies has been improved. Most figures are revised.
Our conclusions are substantially unchange
High Energy Neutrino Signals of Four Neutrino Mixing
We evaluate the upward shower and muon event rates for two characteristic
four neutrino mixing models for extragalactic neutrinos, as well as for the
atmospheric neutrinos, with energy thresholds of 1 TeV, 10 TeV and 100 TeV. We
show that by comparing the shower to muon event rates, one can distinguish
between oscillation and no-oscillation models. By measuring shower and muon
event rates for energy thresholds of 10 TeV and 100 TeV, and by considering
their ratio, it is possible to use extragalactic neutrino sources to determine
the type of four-flavor mixing pattern. We find that one to ten years of data
taking with kilometer-size detector has a very good chance of providing
valuable information about the physics beyond the Standard Model.Comment: version accepted for publication in Phys. Rev.
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