316 research outputs found
Adaptation Advantage to Climate Change Impacts on Road Infrastructure in Africa through 2100
The African continent is facing the potential of a US22 million annually, if they adopt a proactive adaptation policy and a US$54 million annual average, if a reactive approach is adopted. Additionally, countries face an average loss of opportunity to expand road networks from a low of 22 per cent to a high of 235 per cent in the central region.infrastructure, climate change, roads, cost estimates
Strong Electric Fields From Positive Lightning Strokes in the Stratosphere
A balloon payload launched in Brazil has measured vector electric fields from lightning at least an order of magnitude larger than previously reported above 30 km in the stratosphere. During the flight hundreds of lightning events were recorded, including several positive cloud to ground lightning strokes. A two stroke flash, with small (15 kA peak current) and moderate (53 kA) positive strokes at a horizontal range of 34 km, produced field changes over 140 V/m at 34 km altitude. On-board optical lightning detection, recorded with GPS timing, coupled with ground based lightning location gives high time resolution for study of the electric field transient propagation. These measurements imply that lightning electric fields in the mesosphere over large thunderstorms may be much larger than previously measured
Gyrotropic impact upon negatively refracting surfaces
Surface wave propagation at the interface between different types of gyrotropic materials and an isotropic negatively refracting medium, in which the relative permittivity and relative permeability are, simultaneously, negative is investigated. A general approach is taken that embraces both gyroelectric and gyromagnetic materials, permitting the possibility of operating in either the low GHz, THz or the optical frequency regimes. The classical transverse Voigt configuration is adopted and a complete analysis of non-reciprocal surface wave dispersion is presented. The impact of the surface polariton modes upon the reflection of both plane waves and beams is discussed in terms of resonances and an example of the influence upon the GoosâHĂ€nchen shift is given
Higgs-Boson Decay to Four Fermions Including a Single Top Quark Below Threshold
The rare decay modes Higgs four light fermions, and Higgs
single top-quark + three light fermions for , are
presented, and phenomenologically interpreted. The angular correlation between
fermion planes is presented as a test of the spin and intrinsic parity of the
Higgs particle. In Higgs decay to single top, two tree-level graphs contribute
in the standard model (SM); one couples the Higgs to , and
one to t\bar t(\sim g_{top\;yukawa}=m_t/246\GeV). The large Yukawa coupling
for m_t>100\GeV makes the second amplitude competitive or dominant for most
values. Thus the Higgs decay rate to single top directly probes the
SM universal mechanism generating both gauge boson and fermion masses, and
offers a means to infer the Higgs- Yukawa coupling when is kinematically disallowed. We find that the modes at the SSC, and at future high energy,
high luminosity colliders, may be measureable if is not too far above
. We classify non-standard Higgses as gaugeo-phobic, fermio-phobic or
fermio-philic, and discuss the Higgs single top rates for these
classes.Comment: 30 pages, 6 figures (figures available upon request); VAND-TH-93/
Deep Underground Science and Engineering Laboratory - Preliminary Design Report
The DUSEL Project has produced the Preliminary Design of the Deep Underground
Science and Engineering Laboratory (DUSEL) at the rehabilitated former
Homestake mine in South Dakota. The Facility design calls for, on the surface,
two new buildings - one a visitor and education center, the other an experiment
assembly hall - and multiple repurposed existing buildings. To support
underground research activities, the design includes two laboratory modules and
additional spaces at a level 4,850 feet underground for physics, biology,
engineering, and Earth science experiments. On the same level, the design
includes a Department of Energy-shepherded Large Cavity supporting the Long
Baseline Neutrino Experiment. At the 7,400-feet level, the design incorporates
one laboratory module and additional spaces for physics and Earth science
efforts. With input from some 25 science and engineering collaborations, the
Project has designed critical experimental space and infrastructure needs,
including space for a suite of multidisciplinary experiments in a laboratory
whose projected life span is at least 30 years. From these experiments, a
critical suite of experiments is outlined, whose construction will be funded
along with the facility. The Facility design permits expansion and evolution,
as may be driven by future science requirements, and enables participation by
other agencies. The design leverages South Dakota's substantial investment in
facility infrastructure, risk retirement, and operation of its Sanford
Laboratory at Homestake. The Project is planning education and outreach
programs, and has initiated efforts to establish regional partnerships with
underserved populations - regional American Indian and rural populations
The AMANDA Neutrino Telescope
With an effective telescope area of order m for TeV neutrinos, a
threshold near 50 GeV and a pointing accuracy of 2.5 degrees per muon
track, the AMANDA detector represents the first of a new generation of high
energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We
describe early results on the calibration of natural deep ice as a particle
detector as well as on AMANDA's performance as a neutrino telescope.Comment: 12 pages, Latex2.09, uses espcrc2.sty and epsf.sty, 13 postscript
files included. Talk presented at the 18th International Conference on
Neutrino Physics and Astrophysics (Neutrino 98), Takayama, Japan, June 199
Sensitivity of the IceCube Detector to Astrophysical Sources of High Energy Muon Neutrinos
We present the results of a Monte-Carlo study of the sensitivity of the
planned IceCube detector to predicted fluxes of muon neutrinos at TeV to PeV
energies. A complete simulation of the detector and data analysis is used to
study the detector's capability to search for muon neutrinos from sources such
as active galaxies and gamma-ray bursts. We study the effective area and the
angular resolution of the detector as a function of muon energy and angle of
incidence. We present detailed calculations of the sensitivity of the detector
to both diffuse and pointlike neutrino emissions, including an assessment of
the sensitivity to neutrinos detected in coincidence with gamma-ray burst
observations. After three years of datataking, IceCube will have been able to
detect a point source flux of E^2*dN/dE = 7*10^-9 cm^-2s^-1GeV at a 5-sigma
significance, or, in the absence of a signal, place a 90% c.l. limit at a level
E^2*dN/dE = 2*10^-9 cm^-2s^-1GeV. A diffuse E-2 flux would be detectable at a
minimum strength of E^2*dN/dE = 1*10^-8 cm^-2s^-1sr^-1GeV. A gamma-ray burst
model following the formulation of Waxman and Bahcall would result in a 5-sigma
effect after the observation of 200 bursts in coincidence with satellite
observations of the gamma-rays.Comment: 33 pages, 13 figures, 6 table
AAV-mediated rescue of Eps8 expression in vivo restores hair-cell function in a mouse model of recessive deafness
The transduction of acoustic information by hair cells depends upon mechanosensitive stereociliary bundles that project from their apical surface. Mutations or absence of the stereociliary protein EPS8 cause deafness in humans and mice, respectively. Eps8 knockout mice (Eps8â/â) have hair cells with immature stereocilia and fail to become sensory receptors. Here, we show that exogenous delivery of Eps8 using Anc80L65 in P1âP2 Eps8â/â mice in vivo rescued the hair bundle structure of apical-coil hair cells. Rescued hair bundles correctly localize EPS8, WHIRLIN, MYO15, and BAIAP2L2, and generate normal mechanoelectrical transducer currents. Inner hair cells with normal-looking stereocilia re-expressed adult-like basolateral ion channels (BK and KCNQ4) and have normal exocytosis. The number of hair cells undergoing full recovery was not sufficient to rescue hearing in Eps8â/â mice. Adeno-associated virus (AAV)-transduction of P3 apical-coil and P1âP2 basal-coil hair cells does not rescue hair cells, nor does Anc80L65-Eps8 delivery in adult Eps8â/â mice. We propose that AAV-induced gene-base therapy is an efficient strategy to recover the complex hair-cell defects in Eps8â/â mice. However, this therapeutic approach may need to be performed in utero since, at postnatal ages, Eps8â/â hair cells appear to have matured or accumulated damage beyond the point of repair
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