137 research outputs found
A phase-space approach for propagating fieldâfield correlation functions
We show that radiation from complex and inherently random but correlated wave sources can be modelled efficiently by using an approach based on the Wigner distribution function. Our method exploits the connection between correlation functions and the Wigner function and admits in its simplest approximation a direct representation in terms of the evolution of ray densities in phase space. We show that next leading order corrections to the ray-tracing approximation lead to Airy-function type phase space propagators. By exploiting the exact Wigner function propagator, inherently wave-like effects such as evanescent decay or radiation from more heterogeneous sources as well as diffraction and reflection can be included and analysed. We discuss in particular the role of evanescent waves in the near-field of non-paraxial sources and give explicit expressions for the growth rate of the correlation length as a function of the distance from the source. The approximations are validated using full-wave simulations of model sources. In particular, results for the reflection of partially coherent sources from flat mirrors are given where the influence of Airy function corrections can be demonstrated. We focus here on electromagnetic sources at microwave frequencies and modelling efforts in the context of electromagnetic compatibility
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Sources and characteristics of summertime organic aerosol in the Colorado Front Range: perspective from measurements and WRF-Chem modeling
Abstract. The evolution of organic aerosols (OAs) and their precursors in the boundary layer (BL) of the Colorado Front Range during the Front Range Air Pollution and Photochemistry Ăxperiment (FRAPPĂ, JulyâAugust 2014) was analyzed by in situ measurements and chemical transport modeling. Measurements indicated significant production of secondary OA (SOA), with enhancement ratio of OA with respect to carbon monoxide (CO) reaching 0.085±0.003âŻÂ”gâŻmâ3 ppbvâ1. At background mixing ratios of CO, up to ââŒââŻ1.8âŻÂ”gâŻmâ3 background OA was observed, suggesting significant non-combustion contribution to OA in the Front Range. The mean concentration of OA in plumes with a high influence of oil and natural gas (O&G) emissions was ââŒââŻ40âŻ% higher than in urban-influenced plumes. Positive matrix factorization (PMF) confirmed a dominant contribution of secondary, oxygenated OA (OOA) in the boundary layer instead of fresh, hydrocarbon-like OA (HOA). Combinations of primary OA (POA) volatility assumptions, aging of semi-volatile species, and different emission estimates from the O&G sector were used in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulation scenarios. The assumption of semi-volatile POA resulted in greater than a factor of 10 lower POA concentrations compared to PMF-resolved HOA. Including top-down modified O&G emissions resulted in substantially better agreements in modeled ethane, toluene, hydroxyl radical, and ozone compared to measurements in the high-O&G-influenced plumes. By including emissions from the O&G sector using the top-down approach, it was estimated that the O&G sector contributed to â<ââŻ5âŻ% of total OA, but up to 38âŻ% of anthropogenic SOA (aSOA) in the region. The best agreement between the measured and simulated median OA was achieved by limiting the extent of biogenic hydrocarbon aging and consequently biogenic SOA (bSOA) production. Despite a lower production of bSOA in this scenario, contribution of bSOA to total SOA remained high at 40â54âŻ%. Future studies aiming at a better emissions characterization of POA and intermediate-volatility organic compounds (IVOCs) from the O&G sector are valuable
Analysis of nonstationary emissions for efficient characterization of stochastic EM fields
A statistical approach using field-field correlation functions which is obtained from two-probe time domain measurement is used to characterize the radiation from complex devices. The time-frequency analysis provided by the measurement data has shown that significant emissions may only occur for a few percent of the time and a piecewise stationary model of emissions may be most appropriate. In this paper, a sorting technique is applied to short time segments of the nonstationary time-domain data provided by the measurements. These short time segments are sorted into groups according to the characteristics of the emissions, i.e. different emission processes, with the assumption that the stochastic emissions is stationary within each group (process). The ensemble of time segments associated with each group may then be used to obtain the fieldfield correlations for each process. Results of the analysis give promising insights into how to characterize complex and time dependent systems
Analysis of nonstationary emissions for efficient characterization of stochastic EM fields
A statistical approach using field-field correlation functions which is obtained from two-probe time domain measurement is used to characterize the radiation from complex devices. The time-frequency analysis provided by the measurement data has shown that significant emissions may only occur for a few percent of the time and a piecewise stationary model of emissions may be most appropriate. In this paper, a sorting technique is applied to short time segments of the nonstationary time-domain data provided by the measurements. These short time segments are sorted into groups according to the characteristics of the emissions, i.e. different emission processes, with the assumption that the stochastic emissions is stationary within each group (process). The ensemble of time segments associated with each group may then be used to obtain the fieldfield correlations for each process. Results of the analysis give promising insights into how to characterize complex and time dependent systems
Defining the next generation of Plasmodium vivax diagnostic tests for control and elimination: Target product profiles.
The global prevalence of malaria has decreased over the past fifteen years, but similar gains have not been realized against Plasmodium vivax because this species is less responsive to conventional malaria control interventions aimed principally at P. falciparum. Approximately half of all malaria cases outside of Africa are caused by P. vivax. This species places dormant forms in human liver that cause repeated clinical attacks without involving another mosquito bite. The diagnosis of acute patent P. vivax malaria relies primarily on light microscopy. Specific rapid diagnostic tests exist but typically perform relatively poorly compared to those for P. falciparum. Better diagnostic tests are needed for P. vivax. To guide their development, FIND, in collaboration with P. vivax experts, identified the specific diagnostic needs associated with this species and defined a series of three distinct target product profiles, each aimed at a particular diagnostic application: (i) point-of-care of acutely ill patients for clinical care purposes; (ii) point-of-care asymptomatic and otherwise sub-patent residents for public health purposes, e.g., mass screen and treat campaigns; and (iii) ultra-sensitive not point-of-care diagnosis for epidemiological research/surveillance purposes. This report presents and discusses the rationale for these P. vivax-specific diagnostic target product profiles. These contribute to the rational development of fit-for-purpose diagnostic tests suitable for the clinical management, control and elimination of P. vivax malaria
Interprofessional communication with hospitalist and consultant physicians in general internal medicine : a qualitative study
This study helps to improve our understanding of the collaborative environment in GIM, comparing the communication styles and strategies of hospitalist and consultant physicians, as well as the experiences of providers working with them. The implications of this research are globally important for understanding how to create opportunities for physicians and their colleagues to meaningfully and consistently participate in interprofessional communication which has been shown to improve patient, provider, and organizational outcomes
malERA: An updated research agenda for malaria elimination and eradication
Achieving a malaria-free world presents exciting scientific challenges as well as overwhelming health, equity, and economic benefits. WHO and countries are setting ambitious goals for reducing the burden and eliminating malaria through the âGlobal Technical Strategyâ and 21 countries are aiming to eliminate malaria by 2020. The commitment to achieve these targets should be celebrated. However, the need for innovation to achieve these goals, sustain elimination, and free the world of malaria is greater than ever. Over 180 experts across multiple disciplines are engaged in the Malaria Eradication Research Agenda (malERA) Refresh process to address problems that need to be solved. The result is a research and development agenda to accelerate malaria elimination and, in the longer term, transform the malaria communityâs ability to eradicate it globally
Genetic dissection of early endosomal recycling highlights a TORC1-independent role for Rag GTPases
Endocytosed cell surface membrane proteins rely on recycling pathways for their return to the plasma membrane. Although endosome-to-plasma membrane recycling is critical for many cellular processes, much of the required machinery is unknown. We discovered that yeast has a recycling route from endosomes to the cell surface that functions efficiently after inactivation of the sec7-1 allele of Sec7, which controls transit through the Golgi. A genetic screen based on an engineered synthetic reporter that exclusively follows this pathway revealed that recycling was subject to metabolic control through the Rag GTPases Gtr1 and Gtr2, which work downstream of the exchange factor Vam6. Gtr1 and Gtr2 control the recycling pathway independently of TORC1 regulation through the Gtr1 interactor Ltv1. We further show that the early-endosome recycling route and its control though the Vam6 > Gtr1/Gtr2 > Ltv1 pathway plays a physiological role in regulating the abundance of amino acid transporters at the cell surface
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
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