83 research outputs found

    Kinetic Theory for the Interpretation of Measurements on Fluctuations in Radiation Distributions in Finite, Inhomogeneous Systems

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    A kinetic (transport) theory is presented for the first- and second-order (and, if necessary, higher) statistical moments of the number densities of the various particles and/or photons that describe the observable fluctuations in the radiation distribution from an emitting system. This treatment is particularly suitable for the analysis of finite, inhomogeneous systems that may be composed of detectors located outside of a radiating source. Because we are largely concerned with the utility of kinetic theory as a physical theory, considerable emphasis is placed upon an appropriate theoretical description of the actual observables of given experimental situations. The quantum Liouville equation is used to generate the coupled set of transport equations, and basic criteria for the applicability of transport and wave theories are discussed. Quantum-statistical effects are also quite naturally accounted for in cases where they are relevant. It is seen that fluctuation measurements are useful for inferring information relevant to the dynamic interactions within a given system. Such measurements often enjoy the feature of being passive with respect to the interacting system of interest. To illustrate the use of this spatially dependent form of kinetic theory on a system emitting optical radiation, we consider an example that interprets a fluctuation measurement on the radiation emergent from a finite nondispersive blackbody. We conclude by discussing the problems of statistical coupling between the radiation field and detector atom distributionsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86139/1/PhysRev.163.162-RKO.pd

    Business Process Modeling for Successful Implementation of Interorganizational Systems

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    Studies show that the physical implementation of an interorganizational business process or system can be a major source of operational problems and reduced business benefits. Better process modeling has been advocated as a solution. Although powerful modeling tools exist, current practice often gives short-shrift to documenting the physical implementation details that can create or exacerbate such problems. In this paper we describe the modeling approach we devised for the interorganizational business processes and systems we observe in our ongoing fieldwork. Our approach involves using allowable extensions to a popular modeling notation (BPMN), although other modeling tools would work equally well. We illustrate the benefit of our approach in the case of the Internet Payment Platform, a pilot project of the United States Department of the Treasury

    Identification of a triplet pair intermediate in singlet exciton fission in solution.

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    Singlet exciton fission is the spin-conserving transformation of one spin-singlet exciton into two spin-triplet excitons. This exciton multiplication mechanism offers an attractive route to solar cells that circumvent the single-junction Shockley-Queisser limit. Most theoretical descriptions of singlet fission invoke an intermediate state of a pair of spin-triplet excitons coupled into an overall spin-singlet configuration, but such a state has never been optically observed. In solution, we show that the dynamics of fission are diffusion limited and enable the isolation of an intermediate species. In concentrated solutions of bis(triisopropylsilylethynyl)[TIPS]--tetracene we find rapid (<100 ps) formation of excimers and a slower (∼ 10 ns) break up of the excimer to two triplet exciton-bearing free molecules. These excimers are spectroscopically distinct from singlet and triplet excitons, yet possess both singlet and triplet characteristics, enabling identification as a triplet pair state. We find that this triplet pair state is significantly stabilized relative to free triplet excitons, and that it plays a critical role in the efficient endothermic singlet fission process.H.L.S was supported by the Winton Programme for the Physics of Sustainability and A.J.M received funding from the Engineering and Physical Sciences Research Council.This is the accepted manuscript. The final version is available at http://www.pnas.org/content/112/25/7656.abstract

    Development of Level 1b Calibration and Validation Readiness, Implementation and Management Plans for GOES-R

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    A complement of Readiness, Implementation and Management Plans (RIMPs) to facilitate management of post-launch product test activities for the official Geostationary Operational Environmental Satellite (GOES-R) Level 1b (L1b) products have been developed and documented. Separate plans have been created for each of the GOES-R sensors including: the Advanced Baseline Imager (ABI), the Extreme ultraviolet and X-ray Irradiance Sensors (EXIS), Geostationary Lightning Mapper (GLM), GOES-R Magnetometer (MAG), the Space Environment In-Situ Suite (SEISS), and the Solar Ultraviolet Imager (SUVI). The GOES-R program has implemented these RIMPs in order to address the full scope of CalVal activities required for a successful demonstration of GOES-R L1b data product quality throughout the three validation stages: Beta, Provisional and Full Validation. For each product maturity level, the RIMPs include specific performance criteria and required artifacts that provide evidence a given validation stage has been reached, the timing when each stage will be complete, a description of every applicable Post-Launch Product Test (PLPT), roles and responsibilities of personnel, upstream dependencies, and analysis methods and tools to be employed during validation. Instrument level Post-Launch Tests (PLTs) are also referenced and apply primarily to functional check-out of the instruments

    Taking a positive spin: preserved initiative and performance of everyday activities across mild Alzheimer’s, vascular, and mixed dementia

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    Objectives: The literature commonly evaluates those daily activities which are impaired in dementia. However, in the mild stages, people with dementia (PwD) are still able to initiate and perform many of those tasks. With a lack of research exploring variations between different dementia diagnoses, this study sought to investigate those daily activities with modest impairments in the mild stages and how these compare between Alzheimer's disease (AD), vascular dementia (VaD) and mixed dementia. Methods: Staff from memory assessment services from nine National Health Service trusts across England identified and approached informal carers of people with mild dementia. Carers completed the newly revised Interview for Deteriorations in Daily Living Activities in Dementia 2 assessing the PwD's initiative and performance of instrumental activities of daily living (IADLs). Data were analysed using analysis of variance and Chi-square tests to compare the maintenance of IADL functioning across AD, VaD, and mixed dementia. Results: A total of 160 carers returned the Interview for Deteriorations in Daily Living Activities in Dementia 2, of which 109, 21, and 30 cared for someone with AD, VaD, and mixed dementia, respectively. There were significant variations across subtypes, with AD showing better preserved initiative and performance than VaD for several IADLs. Overall, PwD showed greater preservation of performance than initiative, with tasks such as preparing a hot drink and dressing being best maintained. Conclusion: Findings can help classify dementia better into subtypes in order to receive bespoke support. It suggests that interventions should primarily address initiative to improve overall functioning

    Validation of Reference Genes for the Relative Quantification of Gene Expression in Human Epicardial Adipose Tissue

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    BACKGROUND: Relative quantification is a commonly used method for assessing gene expression, however its accuracy and reliability is dependent upon the choice of an optimal endogenous control gene, and such choice cannot be made a priori. There is limited information available on suitable reference genes to be used for studies involving human epicardial adipose tissue. The objective of the current study was to evaluate and identify optimal reference genes for use in the relative quantification of gene expression in human epicardial fat depots of lean, overweight and obese subjects. METHODOLOGY/PRINCIPAL FINDINGS: Some of the commonly used reference genes including 18S, ACTB, RPL27, HPRT, CYCA, GAPDH, RPLPO, POLR2A and B2M were quantified using real-time PCR analysis. The expression stability of these genes was evaluated using Genorm, Normfinder and Bestkeeper algorithms. In addition, the effect of sample size on the validation process was studied by randomly categorizing subjects in two cohorts of n = 2 and n = 33. CONCLUSIONS/SIGNIFICANCE: CYCA, GAPDH and RPL27 were identified as the most stable genes common to all three algorithms and both sample sizes. Their use as reference gene pairs might contribute to the enhanced robustness of relative quantification in the studies involving the human epicardial adipose tissue

    Interleukin-6 Contributes to Inflammation and Remodeling in a Model of Adenosine Mediated Lung Injury

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    Chronic lung diseases are the third leading cause of death in the United States due in part to an incomplete understanding of pathways that govern the progressive tissue remodeling that occurs in these disorders. Adenosine is elevated in the lungs of animal models and humans with chronic lung disease where it promotes air-space destruction and fibrosis. Adenosine signaling increases the production of the pro-fibrotic cytokine interleukin-6 (IL-6). Based on these observations, we hypothesized that IL-6 signaling contributes to tissue destruction and remodeling in a model of chronic lung disease where adenosine levels are elevated.We tested this hypothesis by neutralizing or genetically removing IL-6 in adenosine deaminase (ADA)-deficient mice that develop adenosine dependent pulmonary inflammation and remodeling. Results demonstrated that both pharmacologic blockade and genetic removal of IL-6 attenuated pulmonary inflammation, remodeling and fibrosis in this model. The pursuit of mechanisms involved revealed adenosine and IL-6 dependent activation of STAT-3 in airway epithelial cells.These findings demonstrate that adenosine enhances IL-6 signaling pathways to promote aspects of chronic lung disease. This suggests that blocking IL-6 signaling during chronic stages of disease may provide benefit in halting remodeling processes such as fibrosis and air-space destruction
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