7,536 research outputs found
Sterilizable photomultiplier tubes Final report
Environment, static acceleration, vibration, shock, gas contamination, and life tests in development of sterilizable photomultipliers for space program
Improved sterilizable multiplier phototubes Final report
Development of sterilizable multiplier phototube for scintillation counte
Declarative process modeling in BPMN
Traditional business process modeling notations, including the standard Business Process Model and Notation (BPMN), rely on an imperative paradigm wherein the process model captures all allowed activity flows. In other words, every flow that is not specified is implicitly disallowed. In the past decade, several researchers have exposed the limitations of this paradigm in the context of business processes with high variability. As an alternative, declarative process modeling notations have been proposed (e.g., Declare). These notations allow modelers to capture constraints on the allowed activity flows, meaning that all flows are allowed provided that they do not violate the specified constraints. Recently, it has been recognized that the boundary between imperative and declarative process modeling is not crisp. Instead, mixtures of declarative and imperative process modeling styles are sometimes preferable, leading to proposals for hybrid process modeling notations. These developments raise the question of whether completely new notations are needed to support hybrid process modeling. This paper answers this question negatively. The paper presents a conservative extension of BPMN for declarative process modeling, namely BPMN-D, and shows that Declare models can be transformed into readable BPMN-D models. © Springer International Publishing Switzerland 2015
Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final Report. Volume III: Silicon sheet: wafers and ribbons
The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development.
The primary objective of the Silicon Sheet Task of the FSA Project was the development of one or more low-cost technologies for producing silicon sheet suitable for processing into cost-eompetitive solar cells. Silicon sheet refers to high-purity crystalline silicon of size and thickness for fabrication into solar cells.
The Task effort began with state-of-the-art sheet technologies and then solicited and supported any new silicon sheet alternatives that had the potential to achieve the Project goals.
A total of 48 contracts were awarded that covered work in the areas of ingot growth and casting, wafering, ribbon growth, other sheet technologies, and programs of supportive research. Periodic reviews of each sheet technology were held, assessing the technical progress and the long-range potential. Technologies that failed to achieve their promise, or seemed to have lower probabilities for success in comparison with others, were dropped. A series of workshops was initiated to assess the state of the art, to provide insights into problems remaining to be addressed, and to support technology transfer.
The Task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high-quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the Task cost goals were not achieved.
This FSA Final Report (JPL Publication 86-31, 5101-289, DOE/JPL 1012-125, October 1986) is composed of eight volumes, consisting of an Executive Summary and seven technology reports:
Volume I: Executive Summary.
Volume II: Silicon Material.
Volume III: Silicon Sheet: Wafers and Ribbons
Volume IV: High-Efficiency Solar Celis.
Volume V: Process Development.
Volume VI: Engineering Sciences and Reliability.
Volume VII: Module Encapsulation.
Volume VIII: Project Analysis and Integration.
Two supplemental reports included in the final report package are:
FSA Project: 10 Years of Progress, JPL Document 400-279. 5101-279, October 1985.
Summary of FSA Project Documentation: Abstracts of Published Documents, 1975 to 1986, JPL Publication 82-79 (Revision 1),5101-221, DOE/JPL-1 012-76, September 1986
Infrared light emission from atomic point contacts
Gold atomic point contacts are prototype systems to evidence ballistic
electron transport. The typical dimension of the nanojunction being smaller
than the electron-phonon interaction length, even at room temperature,
electrons transfer their excess energy to the lattice only far from the
contact. At the contact however, favored by huge current densities,
electron-electron interactions result in a nano hot electron gas acting as a
source of photons. Using a home built Mechanically Controlled Break Junction,
it is reported here, for the first time, that this hot electron gas also
radiates in the infrared range (0.2eV to 1.2eV). Moreover, in agreement with
the pioneering work of Tomchuk, we show that this radiation is compatible with
a blackbody like spectrum emitted from an electron gas at temperatures of
several thousands of Kelvin given by where ,
and are respectively a fitting parameter, the current flowing and the
applied bias.Comment: 13 pages, 5 figure
Impact of knee marker misplacement on gait kinematics of children with cerebral palsy using the Conventional Gait Model — a sensitivity study
Clinical gait analysis is widely used in clinical routine to assess the function of patients with motor disorders. The proper assessment of the patient’s function relies greatly on the repeatability between the measurements. Marker misplacement has been reported as the largest source of variability between measurements and its impact on kinematics is not fully understood. Thus, the purpose of this study was: 1) to evaluate the impact of the misplacement of the lateral femoral epicondyle marker on lower limb kinematics, and 2) evaluate if such impact can be predicted. The kinematic data of 10 children with cerebral palsy and 10 aged-match typical developing children were included. The lateral femoral epicondyle marker was virtually misplaced around its measured position at different magnitudes and directions. The outcome to represent the impact of each marker misplacement on the lower limb was the root mean square deviations between the resultant kinematics from each simulated misplacement and the originally calculated kinematics. Correlation and regression equations were estimated between the root mean square deviation and the magnitude of the misplacement expressed in percentage of leg length. Results indicated that the lower-limb kinematics is highly sensitive to the lateral femoral epicondyle marker misplacement in the anterior-posterior direction. The joint angles most impacted by the anterior-posterior misplacement were the hip internal-external rotation (5.3° per 10 mm), the ankle internal-external rotation (4.4° per 10 mm) and the knee flexion-extension (4.2° per 10 mm). Finally, it was observed that the lower the leg length, the higher the impact of misplacement on kinematics. This impact was predicted by regression equations using the magnitude of misplacement expressed in percentage of leg length. An error below 5° on all joints requires a marker placement repeatability under 1.2% of the leg length. In conclusion, the placement of the lateral femoral epicondyle marker in the antero-posterior direction plays a crucial role on the reliability of gait measurements with the Conventional Gait Model
Cross-Border Valuation: The International Cost of Equity Capital
How does a firm in one country evaluate an investment in a firm in another country, or how does it evaluate a foreign project that the firm itself is undertaking? The firm must estimate future free cash flows just as in a domestic project, but choosing an appropriate discount rate is a particular challenge. This study examines the determinants of the discount rate for an international acquisition or project by examining the sources of risk in an international setting. These risks include stock-market price risk measured with various versions of the capital asset pricing model, as well as exchange rate risk and political risk. To measure stock market risk, both segmented and integrated models of the world equity markets are considered. The emphasis of the study is on some of the practical aspects of estimation, particular for markets where no comparable investments exist on which to base estimates of risk premiums. To show how each of these risks might be measured, the study reports estimates for a representative French firm, Thals. The estimates range widely depending on whether or not the equity market is globally integrated.
Is the way we're dieting wrong?
Progress in personalized medicine is now being translated to personalized nutrition. A recent proof-of-concept study shows that the increase in blood glucose levels after a meal is highly variable between individuals, but can be predicted by using a computational model that combines information from gut microbiome profiles and dietary questionnaires. This study raises questions about the usefulness of universal diet recommendations, and suggests we might need to move on to personalized diets
Gaining from loss: Meaning making and resolution in emerging adults\u27 low point narratives as predicted by identity development and perceptions of parenting in adolescence
Past research suggests that difficult life events can disrupt the expected flow of life, often necessitating increased cognitive effort and reflection to assimilate into the greater life story. In the present longitudinal study, 104 emerging adults (M=26 years) narrated stories about their most difficult life experience. The relationship was examined between certain characteristics of the participants’ low point narratives (depth of learning and coherent positive resolution) at age 26 with their identity development, feelings of support, and parent-child relationships from late adolescence (M=17) to emerging adulthood. Depth of learning refers to the extent to which participants extract more sophisticated forms of meaning, such as gaining insight, from their life narratives as opposed to more simplistic forms of meaning, such as lesson learning, while coherent positive resolution refers to the ability to come to a clear and positive resolution to low point narratives. Narratives of more serious content and those with themes of mortality contained greater depth of learning than other narratives. Participants who were more diffused in their identity development (i.e., lacking identity exploration and commitment) demonstrated less depth of learning in their narratives while participants who had more advanced identity statuses or who showed an increase in identity development from age 17 to 26 demonstrated greater resolution in their narratives. Coherent positive resolution was a partial mediator in the relationship between perceptions of good parenting at age 17 and self-reporting well-being at age 26. Narrative resolution was a partial mediator in the relationship between concurrent perceptions of family support and well-being at age 26. These results suggest the importance of identity development, healthy parenting and family support as unique contributors to personally meaningful and resolved low point narratives in emerging adulthood
An Observational Assessment of Peer Group Contributions to Adolescent Identity Development
The purpose of this study was to demonstrate that interaction-based peer groups play an important role in adolescents’ identity development. Peer group members’ current identity development and peer group interaction processes were examined as predictors of teens’ later identity exploration and commitment. Participants (n = 1070; 522 girls; Mage = 15.45 years) reported on their identity development and a subset of participants took part in an interactive group decision task within peer triads (n = 258; 86 triads). Task-related interactions were coded for support (openness to opinions) or discouragement (teasing of opinions and controlling behaviours) of group members\u27 individuality. Nineteen to 22 months later, 103 participants from 59 triads completed a second measure of identity development. As expected, hierarchical linear modelling revealed that the most conducive peer groups for teens’ later identity development had members who had yet to secure personal identity commitments and who supported each others’ individuality (high in openness to others’ opinions and low in controlling behaviours). Unexpectedly, opinion-related teasing in groups also related positively to later identity exploration. For adolescents who had yet to engage in identity processes, membership in committed and controlling groups led to greater identity commitment without exploration (i.e., identification with others’ identity choices). These findings provide evidence that interaction-based peer groups may contribute importantly to identity development in mid-adolescence
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