2,133 research outputs found
Multiplexed Dispersive Spectrometers Using Reduced Background Infrared Detectors
The application of multiplex spectrometry to cryogenically cooled LWIR extrinsic photodetectors is limited by system noise. This noise limitation results in a detector NEP that is directly proportional to bandwidth. Therefore, multiplex schemes that require increased bandwidth are not productive of real advantage. However, doubly encoded systems that are based on 2n - 1 or n + N - 1 measurements have the potential to provide a real throughput gain proportional to the number of elements used on the throughput matrix
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Explaining Adherence Success in Sub-Saharan Africa: An Ethnographic Study
Background: Individuals living with HIV/AIDS in sub-Saharan Africa generally take more than 90% of prescribed doses of antiretroviral therapy (ART). This number exceeds the levels of adherence observed in North America and dispels early scale-up concerns that adherence would be inadequate in settings of extreme poverty. This paper offers an explanation and theoretical model of ART adherence success based on the results of an ethnographic study in three sub-Saharan African countries. Methods and Findings: Determinants of ART adherence for HIV-infected persons in sub-Saharan Africa were examined with ethnographic research methods. 414 in-person interviews were carried out with 252 persons taking ART, their treatment partners, and health care professionals at HIV treatment sites in Jos, Nigeria; Dar es Salaam, Tanzania; and Mbarara, Uganda. 136 field observations of clinic activities were also conducted. Data were examined using category construction and interpretive approaches to analysis. Findings indicate that individuals taking ART routinely overcome economic obstacles to ART adherence through a number of deliberate strategies aimed at prioritizing adherence: borrowing and âbeggingâ transport funds, making âimpossible choicesâ to allocate resources in favor of treatment, and âdoing without.â Prioritization of adherence is accomplished through resources and help made available by treatment partners, other family members and friends, and health care providers. Helpers expect adherence and make their expectations known, creating a responsibility on the part of patients to adhere. Patients adhere to promote good will on the part of helpers, thereby ensuring help will be available when future needs arise. Conclusion: Adherence success in sub-Saharan Africa can be explained as a means of fulfilling social responsibilities and thus preserving social capital in essential relationships
Systematic calculation of molecular vibrational spectra through a complete Morse expansion
We propose an accurate and efficient method to compute vibrational spectra of
molecules, based on exact diagonalization of an algebraically calculated matrix
based on powers of Morse coordinate. The present work focuses on the 1D
potential of diatomic molecules: as typical examples, we apply this method to
the standard Lennard-Jones oscillator, and to the ab initio potential of the H2
molecule. Global cm-1 accuracy is exhibited through the H2 spectrum, obtained
through the diagonalization of a 30 x 30 matrix. This theory is at the root of
a new method to obtain globally accurate vibrational spectral data in the
context of the multi-dimensional potential of polyatomic molecules, at an
affordable computational cost.Comment: 30 pages including 6 figure
Quantum trajectory perspective of atom-field interaction in attosecond time scale
Here the ionization and high harmonic generation in Hydrogen and Helium by
using quantum (hydrodynamic) trajectories is analyzed theoretically. The
quantum trajectories allow a self-contained treatment of the electron exchange
and correlation effects without introducing ad hoc potentials into the
Schrodinger equation. Our approach predicts the correct high harmonic spectra
and the attosecond pulses generated by the Helium atom beyond the single active
electron approximation. It can be used to study complex multi-electron systems
and their interaction with laser field of both high and low intensity.Comment: 8 pages, 4 figure
Circumstellar discs: What will be next?
This prospective chapter gives our view on the evolution of the study of
circumstellar discs within the next 20 years from both observational and
theoretical sides. We first present the expected improvements in our knowledge
of protoplanetary discs as for their masses, sizes, chemistry, the presence of
planets as well as the evolutionary processes shaping these discs. We then
explore the older debris disc stage and explain what will be learnt concerning
their birth, the intrinsic links between these discs and planets, the hot dust
and the gas detected around main sequence stars as well as discs around white
dwarfs.Comment: invited review; comments welcome (32 pages
Modelling groundwater rebound in recently abandoned coalfields using DInSAR
Advances in differential interferometric synthetic aperture radar (DInSAR) processing algorithms, such as the Intermittent Small Baseline Subset (ISBAS), and increased data availability from SAR systems, such as Sentinel-1, provide the opportunity to increase the spatial and temporal density of ground deformation measurements. Such measurements, when combined with modelling, have the potential to make a significant cost-effective contribution to the progressive abandonment strategy of recently closed coalfields. Applications of DInSAR over coalfields have observed heave in coal measures rocks and temporal correlations between the rise of mine water and deformation time-series. The cessation of systematic dewatering can have a variety of detrimental impacts and knowledge of the time-scales (i.e. the rate of rebound) and structure of the mine system are crucial to the remediation strategy. Although mine plans and borehole measurements provide vital information in this regard, mine plans are often incomplete or inaccurate, whereas monitoring boreholes are spatially sparse. Consequently, groundwater can flow in unanticipated directions via goaf, mine shafts and roadways, making it difficult to determine where the impacts of rebound are likely to occur. In this study, ground deformation data obtained using ISBAS DInSAR on ENVISAT (2002â2009) and Sentinel-1 (2015â2019) data are used to develop a simple method to model groundwater rebound in abandoned coalfields. A forward analytical model based upon the principle of effective stress and mine water ponds is first implemented to estimate surface heave in response to changes in groundwater levels measured in monitoring boreholes. The forward model is then calibrated and validated using the ground deformation data. The DInSAR data were subsequently inverted to map the change in groundwater levels in greater detail across the coalfield and forecast surface discharges in order to support mitigation strategies
THE TOOLS AND MONTE CARLO WORKING GROUP Summary Report from the Les Houches 2009 Workshop on TeV Colliders
This is the summary and introduction to the proceedings contributions for the
Les Houches 2009 "Tools and Monte Carlo" working group.Comment: 144 Pages. Workshop site
http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were
Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skand
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