1,834 research outputs found
Vibrational effects in laser driven molecular wires
The influence of an electron-vibrational coupling on the laser control of
electron transport through a molecular wire that is attached to several
electronic leads is investigated. These molecular vibrational modes induce an
effective electron-electron interaction. In the regime where the wire electrons
couple weakly to both the external leads and the vibrational modes, we derive
within a Hartree-Fock approximation a nonlinear set of quantum kinetic
equations. The quantum kinetic theory is then used to evaluate the laser
driven, time-averaged electron current through the wire-leads contacts. This
novel formalism is applied to two archetypical situations in the presence of
electron-vibrational effects, namely, (i) the generation of a ratchet or pump
current in a symmetrical molecule by a harmonic mixing field and (ii) the laser
switching of the current through the molecule.Comment: 12 pages, 7 figures, RevTeX4 require
Energy based method for numerical fatigue analysis of multidirectional carbon fibre reinforced plastics
This paper describes experiments on multiaxial fibre reinforced plastic laminates, which were performed to obtain calibration data for numerical fatigue analyses. For this purpose, fatigue tests of laminates with multidirectional layers subjected to constant amplitude and block loading (0 <= R<1 or R<1) were analysed. The presented simulation results display the fatigue behaviour of carbon fibre reinforced plastics for unidirectional loading conditions and a selected laminate
Offenders, Judges, and Officers Rate the Relative Severity of Alternative Sanctions Compared to Prison
Recent work suggests that offenders rate several alternatives as more severe than imprisonment. We build on this literature by comparing punishment exchange rates generated by criminal court judges with rates generated by offenders and their supervising officers. Findings reveal that none of the three groups rates prison as the most severe sanction and judges and officers rate alternatives as significantly less severe than offenders. Offenders are generally willing to serve less of each alternative to avoid imprisonment than judges or officers. Serving correctional sanctions thus appears to reduce the perceived severity of imprisonment and increase the perceived severity of alternatives
Do institutional arrangements make a difference to transport policy and implementation? Lessons for Britain
This paper describes local government decision-making in transport in three areas of the UK, London, West Yorkshire and Edinburgh, in which major changes in local government decision-making structures have taken place over the last decade, and between which arrangements are now very different. The research discusses whether institutional change has had a beneficial or adverse effect, and whether any of the current structures provides a more effective framework for policy development and implementation. The results show that although the sites share a broadly common set of objectives there are differences in devolved responsibilities and in the extent to which various policy options are within the control of the bodies charged with transport policy delivery. The existence of several tiers of government, coupled with the many interactions required between these public sector bodies and the predominantly private sector public transport operators appears to create extra transactional barriers and impedes the implementation of the most effective measures for cutting congestion. There is, however, a compelling argument for the presence of an overarching tier of government to organise travel over a spatial scale compatible with that of major commuter patterns. The extent to which such arrangements currently appear to work is a function of the range of powers and the funding levels afforded to the co-ordinating organisation
Global and Regional Estimates of Prevalent and Incident Herpes Simplex Virus Type 1 Infections in 2012
Herpes simplex virus type 1 (HSV-1) commonly causes orolabial ulcers, while HSV-2 commonly causes genital ulcers. However, HSV-1 is an increasing cause of genital infection. Previously, the World Health Organization estimated the global burden of HSV-2 for 2003 and for 2012. The global burden of HSV-1 has not been estimated.We fitted a constant-incidence model to pooled HSV-1 prevalence data from literature searches for 6 World Health Organization regions and used 2012 population data to derive global numbers of 0-49-year-olds with prevalent and incident HSV-1 infection. To estimate genital HSV-1, we applied values for the proportion of incident infections that are genital.We estimated that 3709 million people (range: 3440-3878 million) aged 0-49 years had prevalent HSV-1 infection in 2012 (67%), with highest prevalence in Africa, South-East Asia and Western Pacific. Assuming 50% of incident infections among 15-49-year-olds are genital, an estimated 140 million (range: 67-212 million) people had prevalent genital HSV-1 infection, most of which occurred in the Americas, Europe and Western Pacific.The global burden of HSV-1 infection is huge. Genital HSV-1 burden can be substantial but varies widely by region. Future control efforts, including development of HSV vaccines, should consider the epidemiology of HSV-1 in addition to HSV-2, and especially the relative contribution of HSV-1 to genital infection
First estimates of the global and regional incidence of neonatal herpes infection
Background Neonatal herpes is a rare but potentially devastating condition with an estimated 60% fatality rate without
treatment. Transmission usually occurs during delivery from mothers with herpes simplex virus type 1 (HSV-1) or
type 2 (HSV-2) genital infection. However, the global burden has never been quantifi ed to our knowledge. We
developed a novel methodology for burden estimation and present fi rst WHO global and regional estimates of the
annual number of neonatal herpes cases during 2010–15.
Methods We applied previous estimates of HSV-1 and HSV-2 prevalence and incidence in women aged 15–49 years to
2010–15 birth rates to estimate infections during pregnancy. We then applied published risks of neonatal HSV
transmission according to whether maternal infection was incident or prevalent with HSV-1 or HSV-2 to generate
annual numbers of incident neonatal infections. We estimated the number of incident neonatal infections by
maternal age, and we generated separate estimates for each WHO region, which were then summed to obtain global
estimates of the number of neonatal herpes infections.
Findings Globally the overall rate of neonatal herpes was estimated to be about ten cases per 100 000 livebirths,
equivalent to a best-estimate of 14 000 cases annually roughly (4000 for HSV-1; 10 000 for HSV-2). We estimated that
the most neonatal herpes cases occurred in Africa, due to high maternal HSV-2 infection and high birth rates. HSV-1
contributed more cases than HSV-2 in the Americas, Europe, and Western Pacifi c. High rates of genital HSV-1
infection and moderate HSV-2 prevalence meant the Americas had the highest overall rate. However, our estimates
are highly sensitive to the core assumptions, and considerable uncertainty exists for many settings given sparse
underlying data.
Interpretation These neonatal herpes estimates mark the fi rst attempt to quantify the global burden of this rare but
serious condition. Better collection of primary data for neonatal herpes is crucially needed to reduce uncertainty and
refi ne future estimates. These data are particularly important in resource-poor settings where we may have
underestimated cases. Nevertheless, these fi rst estimates suggest development of new HSV prevention measures
such as vaccines could have additional benefi ts beyond reducing genital ulcer disease and HSV-associated HIV
transmission, through prevention of neonatal herpes
Radar-derived statistics of convective storms in southeast Queensland
The aim of this study is to examine the statistics of convective storms and their concomitant changes with thermodynamic variability. The thermodynamic variability is analyzed by performing a cluster analysis on variables derived from radiosonde releases at Brisbane Airport in Australia. Three objectively defined regimes are found: a dry, stable regime with mainly westerly surface winds, a moist northerly regime, and a moist trade wind regime. S-band radar data are analyzed and storms are identified using objective tracking software [Thunderstorm Identification, Tracking, Analysis, and Nowcasting (TITAN)]. Storm statistics are then investigated, stratified by the regime subperiods. Convective storms are found to form and maintain along elevated topography. Probability distributions of convective storm size and rain rate are found to follow lognormal distributions with differing mean and variance among the regimes. There was some evidence of trimodal storm-top heights, located at the trade inversion (1.5–2 km), freezing level (3.6–4 km), and near 6 km, but it was dependent on the presence of the trade inversion. On average, storm volume and height are smallest in the trade regime and rain rate is largest in the westerly regime. However, westerly regime storms occur less frequently and have shorter lifetimes, which were attributed to the enhanced stability and decreased humidity profiles. Furthermore, time series of diurnal rain rate exhibited early morning and midafternoon maxima for the northerly and trade regimes but were absent for the westerly regime. The observations indicate that westerly regime storms are primarily driven by large-scale forcing, whereas northerly and trade wind regime storms are more responsive to surface characteristics
Stopping of Charged Particles in a Magnetized Classical Plasma
The analytical and numerical investigations of the energy loss rate of the
test particle in a magnetized electron plasma are developed on the basis of the
Vlasov-Poisson equations, and the main results are presented. The Larmor
rotation of a test particle in a magnetic field is taken into account. The
analysis is based on the assumption that the energy variation of the test
particle is much less than its kinetic energy. The obtained general expression
for stopping power is analyzed for three cases: (i) the particle moves through
a collisionless plasma in a strong homogeneous magnetic field; (ii) the fast
particle moves through a magnetized collisionless plasma along the magnetic
field; and (iii) the particle moves through a magnetized collisional plasma
across a magnetic field. Calculations are carried out for the arbitrary test
particle velocities in the first case, and for fast particles in the second and
third cases. It is shown that the rate at which a fast test particle loses
energy while moving across a magnetic field may be much higher than the loss in
the case of motion through plasma without magnetic field.Comment: 14 pages, 3 figures, LaTe
The SCOUT-O3 Darwin Aircraft Campaign: rationale and mateorology
An aircraft measurement campaign involving the Russian high-altitude aircraft M55 Geophysica and the German DLR Falcon was conducted in Darwin, Australia in November and December 2005 as part of the European integrated
project SCOUT-O3. The overall objectives of the campaign were to study the transport of trace gases through the tropical tropopause layer (TTL), mechanisms of dehydration close to the tropopause, and the role of deep convection in these processes. In this paper a detailed roadmap of the
campaign is presented, including rationales for each flight, and an analysis of the local and large-scale meteorological context in which they were embedded. The campaign took place during the pre-monsoon season which is characterized by a pronounced diurnal evolution of deep convection including a mesoscale system over the Tiwi Islands north of Darwin known as �\x83¢Â�Â�HectorâÂ�Â�. This allowed studying in detail the role of deep convection in structuring the tropical tropopause region, in situ sampling convective overshoots above storm anvils, and probing the structure of anvils and cirrus clouds by Lidar and a suite of in situ instruments onboard the two aircraft. The large-scale flow during the first half of the campaign was such that local flights, away from convection, sampled air masses downstream of the âÂ�Â�cold trapâÂ�Â� region over Indonesia.
Abundant cirrus clouds enabled the study of active dehydration, in particular during two TTL survey flights. The campaign period also encompassed a Rossby wave breaking event transporting stratospheric air to the tropical middle
troposphere and an equatorial Kelvin wave modulating tropopause temperatures and hence the conditions for dehydration
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