783 research outputs found
The Beam Conditions Monitor of the LHCb Experiment
The LHCb experiment at the European Organization for Nuclear Research (CERN)
is dedicated to precision measurements of CP violation and rare decays of B
hadrons. Its most sensitive components are protected by means of a Beam
Conditions Monitor (BCM), based on polycrystalline CVD diamond sensors. Its
configuration, operation and decision logics to issue or remove the beam permit
signal for the Large Hadron Collider (LHC) are described in this paper.Comment: Index Terms: Accelerator measurement systems, CVD, Diamond, Radiation
detector
Onchocerciasis in the Americas: from arrival to (near) elimination
Onchocerciasis (river blindness) is a blinding parasitic disease that threatens the health of approximately 120 million people worldwide. While 99% of the population at-risk for infection from onchocerciasis live in Africa, some 500,000 people in the Americas are also threatened by infection. A relatively recent arrival to the western hemisphere, onchocerciasis was brought to the New World through the slave trade and spread through migration. The centuries since its arrival have seen advances in diagnosing, mapping and treating the disease. Once endemic to six countries in the Americas (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela), onchocerciasis is on track for interruption of transmission in the Americas by 2012, in line with Pan American Health Organization resolution CD48.R12. The success of this public health program is due to a robust public-private partnership involving national governments, local communities, donor organizations, intergovernmental bodies, academic institutions, non-profit organizations and the pharmaceutical industry. The lessons learned through the efforts in the Americas are in turn informing the program to control and eliminate onchocerciasis in Africa. However, continued support and investment are needed for program implementation and post-treatment surveillance to protect the gains to-date and ensure complete elimination is achieved and treatment can be safely stopped within all 13 regional foci
Dynamics of viscous amphiphilic films supported by elastic solid substrates
The dynamics of amphiphilic films deposited on a solid surface is analyzed
for the case when shear oscillations of the solid surface are excited. The two
cases of surface- and bulk shear waves are studied with film exposed to gas or
to a liquid. By solving the corresponding dispersion equation and the wave
equation while maintaining the energy balance we are able to connect the
surface density and the shear viscocity of a fluid amphiphilic overlayer with
experimentally accessible damping coefficients, phase velocity, dissipation
factor and resonant frequency shifts of shear waves.Comment: 19 pages, latex, 3 figures in eps-forma
Multijoule scaling of laser-induced condensation in air
Using 100 TW laser pulses, we demonstrate that laser-induced nanometric
particle generation in air increases much faster than the beam-averaged
incident intensity. This increase is due to a contribution from the photon
bath, which adds up with the previously identified one from the filaments and
becomes dominant above 550 GW/cm2. It appears related to ozone formation via
multiphotondissociation of the oxygen molecules and demonstrates the critical
need for further increasing the laser energy in view of macroscopic effects in
laser-induced condensation
Spectral shaping of laser generated proton beams
The rapid progress in the field of laser particle acceleration has stimulated a debate about the promising perspectives of laser based ion beam sources. For a long time, the beams produced exhibited quasi-thermal spectra. Recent proof-of-principle experiments demonstrated that ion beams with narrow energy distribution can be generated from special target geometries. However, the achieved spectra were strongly limited in terms of monochromacity and reproducibility. We show that microstructured targets can be used to reliably produce protons with monoenergetic spectra above 2 MeV with less than 10% energy spread. Detailed investigations of the effects of laser ablation on the target resulted in a significant improvement of the reproducibility. Based on statistical analysis, we derive a scaling law between proton peak position and laser energy, underlining the suitability of this method for future applications. Both the quality of the spectra and the scaling law are well reproduced by numerical simulations
Prevalence of antibodies against influenza A and B viruses in children in Germany, 2008 to 2010
The prevalence of influenza A and B virus-specific IgG was determined in sera taken between 2008 and 2010 from 1,665 children aged 0-17 years and 400 blood donors in Germany. ELISA on the basis of whole virus antigens was applied. Nearly all children aged nine years and older had antibodies against influenza A. In contrast, 40% of children aged 0-4 years did not have any influenza A virus-specific IgG antibodies. Eighty-six percent of 0-6 year-olds, 47% of 7-12 year-olds and 20% of 13-17 year-olds were serologically naive to influenza B viruses. By the age of 18 years, influenza B seroprevalence reached approximately 90%. There were obvious regional differences in the seroprevalence of influenza B in Germany. In conclusion, seroprevalences of influenza A and influenza B increase gradually during childhood. The majority of children older than eight years have basal immunity to influenza A, while comparable immunity against influenza B is only acquired at the age of 18 years. Children aged 0-6 years, showing an overall seroprevalence of 67% for influenza A and of 14% for influenza B, are especially at risk for primary infections during influenza B seasons
Saturation of the filament density of ultrashort intense laser pulses in air
We experimentally and numerically characterize multiple filamentation of laser pulses with incident intensities of a few TW/cm2. Propagating 100TW laser pulses over 42m in air, we observe a new propagation regime where the filament density saturates. As also evidenced by numerical simulations in the same intensity range, the total number of filaments is governed by geometric constraints and mutual interactions among filaments rather than by the available power in the bea
Factors Associated with the Rapid and Durable Decline in Malaria Incidence in El Salvador, 1980-2017
A decade after the Global Malaria Eradication Program, El
Salvador had the highest burden of malaria in Mesoamerica, with
approximately 20% due to Plasmodium falciparum. A resurgence of
malaria in the 1970s led El Salvador to alter its national
malaria control strategy. By 1995, El Salvador recorded its last
autochthonous P. falciparum case with fewer than 20 Plasmodium
vivax cases annually since 2011. By contrast, its immediate
neighbors continue to have the highest incidences of malaria in
the region. We reviewed and evaluated the policies and
interventions implemented by the Salvadoran National Malaria
Program that likely contributed to this progress toward malaria
elimination. Decentralization of the malaria program, early
regional stratification by risk, and data-driven
stratum-specific actions resulted in the timely and targeted
allocation of resources for vector control, surveillance, case
detection, and treatment. Weekly reporting by health workers and
volunteer collaborators-distributed throughout the country by
strata and informed via the national surveillance system-enabled
local malaria teams to provide rapid, adaptive, and focalized
program actions. Sustained investments in surveillance and
response have led to a dramatic reduction in local transmission,
with most current malaria cases in El Salvador due to
importation from neighboring countries. Additional support for
systematic elimination efforts in neighboring countries would
benefit the region and may be needed for El Salvador to achieve
and maintain malaria elimination. El Salvador's experience
provides a relevant case study that can guide the application of
similar strategies in other countries committed to malaria
elimination
Quantum Theory in Accelerated Frames of Reference
The observational basis of quantum theory in accelerated systems is studied.
The extension of Lorentz invariance to accelerated systems via the hypothesis
of locality is discussed and the limitations of this hypothesis are pointed
out. The nonlocal theory of accelerated observers is briefly described.
Moreover, the main observational aspects of Dirac's equation in noninertial
frames of reference are presented. The Galilean invariance of nonrelativistic
quantum mechanics and the mass superselection rule are examined in the light of
the invariance of physical laws under inhomogeneous Lorentz transformations.Comment: 25 pages, no figures, contribution to Springer Lecture Notes in
Physics (Proc. SR 2005, Potsdam, Germany, February 13 - 18, 2005
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