444 research outputs found
On the nature of Bose-Einstein condensation enhanced by localization
In a previous paper we established that for the perfect Bose gas and the
mean-field Bose gas with an external random or weak potential, whenever there
is generalized Bose-Einstein condensation in the eigenstates of the single
particle Hamiltonian, there is also generalized condensation in the kinetic
energy states. In these cases Bose-Einstein condensation is produced or
enhanced by the external potential. In the present paper we establish a
criterion for the absence of condensation in single kinetic energy states and
prove that this criterion is satisfied for a class of random potentials and
weak potentials. This means that the condensate is spread over an infinite
number of states with low kinetic energy without any of them being
macroscopically occupied
Exactness of the Bogoliubov approximation in random external potentials
We investigate the validity of the Bogoliubov c-number approximation in the
case of interacting Bose-gas in a \textit{homogeneous random} media. To take
into account the possible occurence of type III generalized Bose-Einstein
condensation (i.e. the occurrence of condensation in an infinitesimal band of
low kinetic energy modes without macroscopic occupation of any of them) we
generalize the c-number substitution procedure to this band of modes with low
momentum. We show that, as in the case of the one-mode condensation for
translation-invariant interacting systems, this procedure has no effect on the
exact value of the pressure in the thermodynamic limit, assuming that the
c-numbers are chosen according to a suitable variational principle. We then
discuss the relation between these c-numbers and the (total) density of the
condensate
Comparative measurements of total ozone amount and aerosol optical depth during a campaign at El Arenosillo, Huelva, Spain
A one week field campaign took place in September 2002 at El Arenosillo, Spain. The objective was to compare total ozone column (<I>TOC</I>) and aerosol optical depth (<I>AOD</I>) from near ultraviolet to near infrared, measured by several Spanish and French instruments. Three spectroradiometers, Brewer, SPUV02, and LICOR, and a CIMEL photometer, have been used simultaneously and the results are presented for four clear days. <I>TOC</I> values are given by the Brewer instrument, and by SPUV02, using two different methods. The ground instruments compare satisfactorily (within 5&nbsp;DU) and the values are consistent with TOMS data (within 10&nbsp;DU). <P style="line-height: 20px;"> <I>AOD</I> from the various instruments are compared at seven different wavelengths between 320 nm and 1020 nm: the agreement is very good at 350, 380, and 870 nm; at the four other wavelengths the difference is smaller than 0.03, which can be explained by a relative difference of 4% only between the calibrations of the various instruments. Larger <I>AOD</I> diurnal variations were observed at short wavelengths than in the visible and near infrared; this is most likely due to changes in aerosol size along the day, during the campaign
TiO2- and ZnO-Based Materials for Photocatalysis: Material Properties, Device Architecture and Emerging Concepts
Numerous kinds of photocatalysts such as oxide-, nitride- or sulfide-based semiconductors, conducting polymers or graphene oxide–based materials have emerged since the discovery of water splitting on TiO2 electrodes in 1972. Yet, metal-oxides are still largely the main family of materials promoted into photocatalytic applications
Social Science Considerations for Integrating Aviation Technology, Emergency Services, and Human Resilience
Unmanned aerial systems (UAS) have a range of innovative applications within the field of disaster management, underscoring the potential to enhance human security by integrating UAS across phases of disasters. This paper highlights important social science challenges that must be addressed to ensure the effective integration of UAS, the complex team of teams that respond to disasters, and the populations affected by disasters. Expanding upon points of intersection between UAS capabilities and disaster management identified in recent research, UAS uses in disaster management and corresponding psychosocial considerations are discussed. Broadly, these considerations focus on the training and development of the disaster management multiteam system (MTS) as well as the well-being of disaster responders and the populations they serve. Considerations for mitigation (resilient team infrastructure), preparation (education and training), response (an integrated MTS; responder health), and recovery (population resilience) phases of disaster management are discussed to pave the way for future research and application in this area
Progress report and first operation of the GANIL injector
http://accelconf.web.cern.ch/AccelConf/c81/papers/abp-07.pdfInternational audienc
Integrating Aviation Technology, Emergency Services, and Human Resilience: Considerations from Social Scientists
Unmanned aerial systems (UAS) have a range of applications within the field of disaster response. This presentation offers a novel framework of psychosocial considerations designed to advance UAS and disaster management integration. Social scientists highlight important challenges to the effective integration of three primary entities: UAS, the team of teams that responds to disasters, and populations affected by disasters.
The presentation adopts an emerging theoretical perspective on the intersection between UAS capabilities and disaster phases and extends it by bringing necessary attention to social science issues. Specifically, the framework outlines psychosocial considerations and areas of improvement for preparation (training), response (incident command), and recovery (occupational health; population resilience) phases of disaster management.
First, training curricula must involve the full disaster response multiteam system (MTS; i.e., team of teams) in cross-training that builds a shared identity by operationalizing UAS as a component team. Second, disaster response MTSs must establish incident command structures that incorporate UAS into team communication and coordination networks. Third, the implications of stressors unique to UAS operation need to be better understood in the context of existing cyclical effects of work stress on disaster responder performance and well-being. Finally, as crisis communication affects disaster-impacted communities, populations must be able to leverage UAS as a mechanism for, and not a barrier against, recovery from disaster.
Across the globe, disasters threaten human security. This presentation provides a necessary interdisciplinary perspective on implementing UAS in disaster management to help the world better prepare for, respond to, recover from, and mitigate disasters
Passive remote sensing of tropospheric aerosol and atmospheric correction for the aerosol effect
The launch of ADEOS in August 1996 with POLDER, TOMS, and OCTS instruments on board and the future launch of EOS-AM 1 in mid-1998 with MODIS and MISR instruments on board start a new era in remote sensing of aerosol as part of a new remote sensing of the whole Earth system (see a list of the acronyms in the Notation section of the paper). These platforms will be followed by other international platforms with unique aerosol sensing capability, some still in this century (e.g., ENVISAT in 1999). These international spaceborne multispectral, multiangular, and polarization measurements, combined for the first time with international automatic, routine monitoring of aerosol from the ground, are expected to form a quantum leap in our ability to observe the highly variable global aerosol. This new capability is contrasted with present single-channel techniques for AVHRR, Meteosat, and GOES that although poorly calibrated and poorly characterized already generated important aerosol global maps and regional transport assessments. The new data will improve significantly atmospheric corrections for the aerosol effect on remote sensing of the oceans and be used to generate first real-time atmospheric corrections over the land. This special issue summarizes the science behind this change in remote sensing, and the sensitivity studies and applications of the new algorithms to data from present satellite and aircraft instruments. Background information and a summary of a critical discussion that took place in a workshop devoted to this topic is given in this introductory paper. In the discussion it was concluded that the anticipated remote sensing of aerosol simultaneously from several space platforms with different observation strategies, together with continuous validations around the world, is expected to be of significant importance to test remote sensing approaches to characterize the complex and highly variable aerosol field. So far, we have only partial understanding of the information content and accuracy of the radiative transfer inversion of aerosol information from the satellite data, due to lack of sufficient theoretical analysis and applications to proper field data. This limitation will make the anticipated new data even more interesting and challenging. A main concern is the present inadequate ability to sense aerosol absorption, from space or from the ground. Absorption is a critical parameter for climate studies and atmospheric corrections. Over oceans, main concerns are the effects of white caps and dust on the correction scheme. Future improvement in aerosol retrieval and atmospheric corrections will require better climatology of the aerosol properties and understanding of the effects of mixed composition and shape of the particles. The main ingredient missing in the planned remote sensing of aerosol are spaceborne and ground-based lidar observations of the aerosol profiles
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