390 research outputs found
A Runtime Verification and Validation Framework for Self-Adaptive Software
The concepts that make self-adaptive software attractive also make it more difficult for users to gain confidence that these systems will consistently meet their goals under uncertain context. To improve user confidence in self-adaptive behavior, machine-readable conceptual models have been developed to instrument the adaption behavior of the target software system and primary feedback loop. By comparing these machine-readable models to the self-adaptive system, runtime verification and validation may be introduced as another method to increase confidence in self-adaptive systems; however, the existing conceptual models do not provide the semantics needed to institute this runtime verification or validation. This research confirms that the introduction of runtime verification and validation for self-adaptive systems requires the expansion of existing conceptual models with quality of service metrics, a hierarchy of goals, and states with temporal transitions. Based on this expanded semantics, runtime verification and validation was introduced as a second-level feedback loop to improve the performance of the primary feedback loop and quantitatively measure the quality of service achieved in a state-based, self-adaptive system. A web-based purchasing application running in a cloud-based environment was the focus of experimentation. In order to meet changing customer purchasing demand, the self-adaptive system monitored external context changes and increased or decreased available application servers. The runtime verification and validation system operated as a second-level feedback loop to monitor quality of service goals based on internal context, and corrected self-adaptive behavior when goals are violated. Two competing quality of service goals were introduced to maintain customer satisfaction while minimizing cost. The research demonstrated that the addition of a second-level runtime verification and validation feedback loop did quantitatively improve self-adaptive system performance even with simple, static monitoring rules
Bilevel Inverse Problems in Neuromorphic Imaging
Event or Neuromorphic cameras are novel biologically inspired sensors that
record data based on the change in light intensity at each pixel
asynchronously. They have a temporal resolution of microseconds. This is useful
for scenes with fast moving objects that can cause motion blur in traditional
cameras, which record the average light intensity over an exposure time for
each pixel synchronously. This paper presents a bilevel inverse problem
framework for neuromorphic imaging. Existence of solution to the inverse
problem is established. Second order sufficient conditions are derived under
special situations for this nonconvex problem. A second order Newton type
solver is derived to solve the problem. The efficacy of the approach is shown
on several examples
Investigating students seriousness during selected conceptual inventory surveys
Conceptual inventory surveys are routinely used in education research to
identify student learning needs and assess instructional practices. Students
might not fully engage with these instruments because of the low stakes
attached to them. This paper explores tests that can be used to estimate the
percentage of students in a population who might not have taken such surveys
seriously. These three seriousness tests are the pattern recognition test, the
easy questions test, and the uncommon answers test. These three tests are
applied to sets of students who were assessed either by the Force Concept
Inventory, the Conceptual Survey of Electricity and Magnetism, or the Brief
Electricity and Magnetism Assessment. The results of our investigation are
compared to computer simulated populations of random answers.Comment: 8 pages; submitted to Phys Rev PE
Application of radioactive tracers in the study of sediment movement
CER63DWH-WWS5.For presentation at Federal Inter-Agency Sedimentation Conference, Jackson, Mississippi, January 28-February 1, 1963.Radioactive tracer techniques were employed in order to investigate the dispersion and transport of bed material in a test reach of the North Loup River near Purdum, Nebraska. Sand particles, labelled with Iridium-192, were used as tracers to enable observation of the natural dispersion and transport processes. The amount of radioactivity and the number of tracer particles required for the experiment was determined by considering the sensitivity of the radiation-detection system, the characteristics of the test reach, and radiological safety considerations. In the experiment, the tracer particles were released from a line source which extended across the bed of the stream. As the tracer particles were transported and dispersed downstream, their longitudinal and lateral distributions in the bed were observed by periodic surveys with a sled-mounted scintillation detector, and their vertical distribution in the bed was observed by monitoring core samples. Information obtained from a laboratory calibration of the radiation-detection system under simulated field conditions was used to reduce the field data to a set of tracer-particle concentration-distribution curves. The results of the field study indicate a potential for the wide application of radioactive tracer in sediment studies
The 340B Program, Contract Pharmacies and Hospitals: An Examination of the First 25 Years of their Increasingly Complex Relationship
The 340B Drug Pricing Program, created by Congress in 1992 through the Veterans Health Care Act, has provided discounted drug prices to hospitals and other health care organizations serving a wide population of low-income patients. Some 340B programs use contract pharmacies, an arrangement whereby the hospital or health care organization signs a contract directly with a pharmacy to provide covered pharmacy services at discounted prices.
The federal 340B Drug Pricing Program has provided access to reduced price prescription drugs to over 35,000 individual healthcare facilities and sites certified by the U.S. Department of Health and Human Services (HHS), and clinics have served more than 10 million people in all 50 states, plus commonwealths and U.S. territories. The 340B program has increased profits for hospitals through contract pharmacies because they have still received the same reimbursement but acquired drugs at a lower rate
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Lifestyle and patterns of physical activity in Hadza foragers.
OBJECTIVES: Physically active lifestyles are associated with several health benefits. Physical activity (PA) levels are low in post-industrial populations, but generally high throughout life in subsistence populations. The Hadza are a subsistence-oriented foraging population in Tanzania known for being physically active, but it is unknown how recent increases in market integration may have altered their PA patterns. In this study, we examine PA patterns for Hadza women and men who engage in different amounts of traditional foraging. MATERIALS AND METHODS: One hundred and seventy seven Hadza participants (51% female, 19-87 years) wore an Axivity accelerometer (dominant wrist) for ~6 days during dry season months. We evaluated the effects of age, sex, and lifestyle measures on four PA measures that capture different aspects of the PA profile. RESULTS: Participants engaged in high levels of both moderate-intensity PA and inactivity. Although PA levels were negatively associated with age, older participants were still highly active. We found no differences in PA between participants living in more traditional bush camps and those living in more settled village camps. Mobility was positively associated with step counts for female participants, and schooling was positively associated with inactive time for male participants. CONCLUSIONS: The similarity in PA patterns between Hadza participants in different camp types suggests that high PA levels characterize subsistence lifestyles generally. The sex-based difference in the effects of mobility and schooling on PA could be a reflection of the Hadzas gender-based division of labor, or indicate that changes to subsistence-oriented lifestyles impact women and men in different ways
Cryogenic carbon capture
Cryogenic Carbon Captureâ„¢ (CCC) removes CO2 from flue gas in a bolt on retrofittable, cost-effective, and energy-efficient process. The process also provides grid-level energy storage capable of storing and releasing energy at hundreds of megawatt rates at high efficiency and minimal cost beyond the costs of the carbon capture technology. The energy storage can level daily load fluctuations and responds to intermittent power sources on time scales comparable to solar and wind farms. The technology cools flue gases to their condensation (desublimation) point forming solid CO2, separates the solids from the residual gases, pressurizes the solids, and reheats both streams to room temperature. The process produces two nominally ambient-temperature streams: liquid CO2 at about 150 bar and the light gases at ambient pressure. Essentially all of the sensible heating occurs through energy integration. The technology primary advantages include
(a) consumes minimal energy for CO2 capture (appx. 0.7 GJe/tonne CO2 for typical coal flue gas)
(b) costs relatively little (2.5 cents/kWh or less increase in COE)
(c) retrofits existing plants with virtually no upstream modification
(d) removes essentially all other pollutants except CO, including SOx, NOx, Hg, PMxx, and HC;
(e) requires no additional cooling water;
(f) requires no steam or other resources from the process other than electrical power
Fully integrated versions of the technology at up to 1 tonne of CO2/day have operated on fuels including subbituminous coal, bituminous coal, natural gas, biomass, municipal waste and tires and at sites that include utility power plants, cement kilns, heat plants, and pilot-scale research combustors. This presentation summarizes the technology, field test results, and development plans for this technology. Further information is available at www.sesinnovation.com
Restoration of the Nisqually River Delta and increased rearing opportunities for salmonids
Estuarine wetlands in the Salish Sea provide important rearing habitat for migrating juvenile Pacific salmon, contributing to their overall productivity and ocean survival. Substantial loss of historical estuarine habitat in the Salish Sea due to diking, draining and development has contributed to the decline of Pacific salmon populations (Oncorhynchus spp.). The return of tidal inundation through a series of dike removals to 364 hectares of the Nisqually River Delta (Olympia, Washington, USA) represents one of the most significant advances to date towards the recovery of the threatened Nisqually Fall Chinook stock. Our objective was to assess the collective Nisqually Delta restorations in terms of increased rearing opportunity for juvenile salmon. Metrics consisted of physical conditions that allow juvenile salmon to access the estuarine restorations such as delta connectivity, full tidal inundation and channel development. Unlike most studies, we put these physical metrics in terms of juvenile Chinook by constraining our inundation model to outmigration season (Mar – Aug) and those tidal depths supporting juvenile Chinook (\u3e 0.4 m). We used these criteria, verified by presence of juvenile salmonids in three restored and two reference tidal channels, to measure the change in opportunity potential from pre-restoration to post-restoration condition for juvenile Chinook to access and rear in the Nisqually estuary. We found landscape connectivity to be strongly tied to tidal height and increased throughout the estuary with dike removal. Tidal channel development was most rapid in the first and second year post-restoration; with channel outlets widening and deepening to accommodate restored tidal prisms. Chum salmon, natural origin Chinook and hatchery origin Chinook salmon accessed all three restored marshes within two years post-restoration, although responses varied among years, marshes and salmon species. These results suggest that the Nisqually Delta restorations are providing increased rearing opportunity for juvenile salmon
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