1,574 research outputs found
Decoupling Extreme Programming From Byzantine Fault Tolerance in Multicast Algorithms
Unified embedded archetypes have led to many practical advances, including fiber-optic cables and Internet QoS. In fact, few biologists would disagree with the simulation of agents, demonstrates the significant importance of machine learning. Kapia, our new heuristic for the con- struction of extreme programming, is the solution to all of these problems
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Numerical Simulations in Support of a Long-Term Test of Gas Production From Hydrate Accumulations on the Alaska North Slope: Water Production and Associated Design and Management Issues
We investigated numerical simulation strategies for a long-term test of depressurization-induced gas production from the B1 Sand of Unit B at the Hydrate-01 Stratigraphic Test Well. The main objective of this study was to estimate fluid production rates (with emphasis on water production) under a variety of conditions and production scenarios and contribute new insights to the design and management of the field test. In the first part of the study, we investigated the system response to a three-step depressurization process using two limiting sets of flow properties─the expected maximum and minimum intrinsic and effective permeabilities─for the very heterogeneous reservoir. In the second part, we investigated the effect of the production interval length and placement within the formation relative to the boundaries of the hydrate-bearing unit. The best performing well configuration was used in the third part of the study, which used the most representative subsurface flow properties to investigate the effect of the depressurization strategy on the production performance. The best overall performance (largest gas production with modest water production and a strong response at the observation wells) was obtained with a 10 m-long well situated 3 m below the top of the formation and a three-step depressurization scheme at 15-day intervals to a terminal bottomhole pressure of 2.8 MPa. The overall production performance was enhanced by a faster rate of depressurization. Estimated water production rates in all cases were limited and easily manageable. None of the tested well configurations or depressurization strategies significantly reduced water production without also severely reducing gas production. In all the investigated cases, 95% of the long-term fraction of produced water was replenished by inflows from the boundaries and could not be reduced. These substantial water inflows are an unavoidable feature of HU-B and cannot be easily mitigated by a hydraulic control
Racial Bias And Its Relationship With Moral Blame
The proposed studies incorporate a reaction time paradigm and a moral updating paradigm in order to test the effects of both explicit and implicit racial biases on the process of moral blame. This will also help distinguish between two theories on moral blame. The first being that when biases are presented, that only the outcome of the blame judgment is affected, and the second being that people with high bias versus people with low bias process information differently, leading to different blame judgments
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Modeling of Oceanic Gas Hydrate Instability and Methane Release in Response to Climate Change
Paleooceanographic evidence has been used to postulate that methane from oceanic hydrates may have had a significant role in regulating global climate, implicating global oceanic deposits of methane gas hydrate as the main culprit in instances of rapid climate change that have occurred in the past. However, the behavior of contemporary oceanic methane hydrate deposits subjected to rapid temperature changes, like those predicted under future climate change scenarios, is poorly understood. To determine the fate of the carbon stored in these hydrates, we performed simulations of oceanic gas hydrate accumulations subjected to temperature changes at the seafloor and assessed the potential for methane release into the ocean. Our modeling analysis considered the properties of benthic sediments, the saturation and distribution of the hydrates, the ocean depth, the initial seafloor temperature, and for the first time, estimated the effect of benthic biogeochemical activity. The results show that shallow deposits--such as those found in arctic regions or in the Gulf of Mexico--can undergo rapid dissociation and produce significant methane fluxes of 2 to 13 mol/yr/m{sup 2} over a period of decades, and release up to 1,100 mol of methane per m{sup 2} of seafloor in a century. These fluxes may exceed the ability of the seafloor environment (via anaerobic oxidation of methane) to consume the released methane or sequester the carbon. These results will provide a source term to regional or global climate models in order to assess the coupling of gas hydrate deposits to changes in the global climate
Auditory In-Vehicle Technologies to Support Older Drivers
OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationship OBJECTIVES Population aging, in combination with improved health care and more active lifestyles well into advanced age, have resulted in an increased number of older adults driving more miles than ever before. Unfortunately, these older drivers are over-represented in motor vehicle crashes and crash-related fatalities. Rather than the risk-tasking behaviors observed in young drivers, the collisions of older drivers frequently involve perceptual-cognitive errors. Advanced in-vehicle technologies have the potential to function as sensory-cognitive aids and may offset the negative impact of age-related changes in sensory and cognitive abilities. Collision Avoidance Systems (CASs) function as sensory aids to augment hazard detection capabilities, and therefore may be of particular benefit to older drivers. Navigation aids can offset the working memory requirements of wayfinding, and auditory guidance directions may reduce the visual demands of searching for street signs and reading maps. However, these advanced systems also have the potential to increase the information processing demands of the driving task or distract drivers, particularly if they are not designed in accordance with the sensory and perceptual capabilities of older adults. A series of experiments aimed at examining the impact of sensory-cognitive characteristics of auditory navigational aids on driver wayfinding, performance on a visual peripheral detection task, and neurophysiological, behavioral and subjective indices of driver mental workload and performance were conducted. METHODS Results of two investigations will be discussed. The first investigation examined the impact of amplitude level on working memory. Older adults frequently exhibit reduced complex working memory span. However, recent evidence indicates that increasing a sound’s amplitude increases its duration in echoic memory (Baldwin, in press). Based on these findings, we hypothesized that increasing the amplitude of verbal material would improve working memory efficiency. RESULTS In support of this hypothesis, a strong positive correlation between the amplitude level at which the verbal material was presented and complex working memory span as measured by a version of Daneman and Carpenter’s (1980) Listening span task was observed. This positive relationshi
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The Use of Horizontal Wells in Gas Production from Hydrate Accumulations
The amounts of hydrocarbon gases trapped in natural hydrate accumulations are enormous, leading to a recent interest in the evaluation of their potential as an energy source. Earlier studies have demonstrated that large volumes of gas can be readily produced at high rates for long times from gas hydrate accumulations by means of depressurization-induced dissociation, using conventional technology and vertical wells. The results of this numerical study indicate that the use of horizontal wells does not confer any practical advantages to gas production from Class 1 deposits. This is because of the large disparity in permeabilities between the hydrate layer (HL) and the underlying free gas zone, leading to a hydrate dissociation that proceeds in a horizontally dominant direction and is uniform along the length of the reservoir. When horizontal wells are placed near the base of the HL in Class 2 deposits, the delay in the evolution of a significant gas production rate outweighs their advantages, which include higher rates and the prevention of flow obstruction problems that often hamper the performance of vertical wells. Conversely, placement of a horizontal well near to top of the HL can lead to dramatic increases in gas production from Class 2 and Class 3 deposits over the corresponding production from vertical wells
Government review of the Mod-2 wind turbine (as-built)
The findings and recommendations of the Government committee formed to conduct an as-built review of the three Mod-2 wind turbine units at Goldendale, Washington are given. The purpose of the review was to identify any critical deficiencies in machine components that could result in failure, and to recommend any necessary corrective action before resuming safe machine operation. The review concluded that one of the deficiencies identified would preclude planned attended or unattended operation, provided that certain corrective actions were implemented
The Impact of State Mandated Healthcare-Associated Infection Reporting on Infection Prevention and Control Departments in Acute Care Hospitals: Results from a National Survey
Background: In addition to federally mandated reporting, most US states have adopted legislation requiring hospitals to submit healthcare-associated infection (HAI) data. Evidence that state HAI laws have increased patient safety and reduced HAI rates is inconsistent, however, and resources needed to comply are considerable. We evaluated the impact of state HAI laws on infection prevention and control departments (IPCD).
Methods: Web-based survey of a national sample of hospital IPCD was conducted in Fall 2011; all non-VA hospitals enrolled in the National Healthcare Safety Network were eligible to participate. States with HAI laws effective prior to Fall 2011 were identified using systematic legal review. Variations in IPCD resources and characteristics in states with and without laws were compared using χ2or Wilcoxon-Mann-Whitney tests. Multinomial logistic regression was used to identify increases or decreases, vs no change, in resources and characteristics.
Results: 1,038 IPCD provided complete data (30% response rate); 756 (73%) were located in states with laws. When asked how mandatory reporting affected their IPCD, more respondents in states with laws reported differences in resources (42% vs 33%, p \u3c 0.01), time for routine activities other than for mandatory reporting (79% vs 71%, p \u3c 0.01), influence in hospital decision making (55% vs 48%, p \u3c 0.05), and visibility of their department (75% vs 65%, p \u3c 0.001); they also spent more hours per week fulfilling mandatory reporting requirements (17 vs 13, p \u3c 0.0001). Based on regression analysis, respondents in states with laws were more likely to report increased resources (p = 0.02) and influence (p = 0.04) and decreased time for routine activities (p \u3c 0.01). Perception of visibility in the hospital was mixed with reports of both increased (p \u3c 0.001) and decreased (p = 0.01) visibility vs the same.
Conclusion: Respondents in states with laws reported a significantly higher burden to their IPCD, beyond what was required by federally mandated HAI reporting alone. However, they also reported receiving increased resources to offset demands on time for routine activities and fulfilling reporting requirements. Further research is needed to investigate resources necessary to comply with state HAI laws, and to evaluate their unintended consequences
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