2,669 research outputs found

    Altruism among relatives and non-relatives

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    The amount of their own monetary reward that undergraduate participants claimed they were willing to forgo, in order to give $75 to another person, decreased hyperbolically as social distance increased between the participant and the other person. Relatives tended to be ranked at closer social distances than were non-relatives. However, even at the same social distance, participants were willing to forgo significantly more money for the benefit of relatives than for the benefit of non-relatives. These results imply that altruism is determined by factors in addition to social distance

    Spontaneous Breaking of Gauge Groups to Discrete Symmetries

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    Many models of beyond Standard Model physics connect flavor symmetry with a discrete group. Having this symmetry arise spontaneously from a gauge theory maintains compatibility with quantum gravity and can be used to systematically prevent anomalies. We minimize a number of Higgs potentials that break gauge groups to discrete symmetries of interest, and examine their scalar mass spectra.Comment: 45 page

    The Sensing Capacity of Sensor Networks

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    This paper demonstrates fundamental limits of sensor networks for detection problems where the number of hypotheses is exponentially large. Such problems characterize many important applications including detection and classification of targets in a geographical area using a network of sensors, and detecting complex substances with a chemical sensor array. We refer to such applications as largescale detection problems. Using the insight that these problems share fundamental similarities with the problem of communicating over a noisy channel, we define a quantity called the sensing capacity and lower bound it for a number of sensor network models. The sensing capacity expression differs significantly from the channel capacity due to the fact that a fixed sensor configuration encodes all states of the environment. As a result, codewords are dependent and non-identically distributed. The sensing capacity provides a bound on the minimal number of sensors required to detect the state of an environment to within a desired accuracy. The results differ significantly from classical detection theory, and provide an ntriguing connection between sensor networks and communications. In addition, we discuss the insight that sensing capacity provides for the problem of sensor selection.Comment: Submitted to IEEE Transactions on Information Theory, November 200

    Title VII: Limitations and Qualifications

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    Sensing Capacity for Markov Random Fields

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    This paper computes the sensing capacity of a sensor network, with sensors of limited range, sensing a two-dimensional Markov random field, by modeling the sensing operation as an encoder. Sensor observations are dependent across sensors, and the sensor network output across different states of the environment is neither identically nor independently distributed. Using a random coding argument, based on the theory of types, we prove a lower bound on the sensing capacity of the network, which characterizes the ability of the sensor network to distinguish among environments with Markov structure, to within a desired accuracy.Comment: To appear in the proceedings of the 2005 IEEE International Symposium on Information Theory, Adelaide, Australia, September 4-9, 200

    TIGHT SHOE NIGHT

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    Tests of Ocean-Tide Models by Analysis of Satellite-To-Satellite Range Measurements: An Update

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    Seven years of GRACE intersatellite range-rate measurements are used to test the new ocean tide model FES2014 and to compare against similar results obtained with earlier models. These qualitative assessments show that FES2014 represents a marked improvement in accuracy over its earlier incarnation, FES2012, with especially notable improvements in the Arctic Ocean for constituents K(sub 1) and S(sub 2). Degradation appears to have occurred in two anomalous regions: the Ross Sea for the O(sub 1) constituent and the Weddell Sea for M(sub 2)

    What can the take-up of other programs teach us about how to improve take-up of health insurance programs?

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    Many uninsured Americans are already eligible for free or low-cost public coverage through Medicaid or CHIP but do not take up that coverage. Several other programs, such as food stamps and unemployment insurance, also have less than complete take-up rates and take-up rates vary considerably among programs. This paper examines the take-up literature across a variety of programs to learn what effects non-financial features, such as administrative complexity, have on take-up. We find that making benefit receipt automatic is the most effective means of ensuring high take-up, while there is little evidence that stigma is important. Overall, surprisingly little is known about the quantitative impact, of non-financial characteristics of programs on take-up. New research that could be used to draw measurable causal inferences about how features as administrative complexity, renewal rules, and organizational structure affect participation, would be extremely valuable.

    Psychiatric nurses’ views on criteria for psychiatric intensive care: acute and intensive care staff compared

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    Aim: To explore and investigate differences between the views of qualified nurses working in psychiatric intensive care units (PICUs) and acute care wards on which patients are appropriate for PICU care. Background: Previous research on the area of psychiatric intensive care highlights the great differences that exist in all aspects of service provision, from unit size and staffing levels to treatment approaches and physical environment. One of the most common areas of controversy is the type of client behaviour that warrants admission to the PICU. Method: Structured interviews of 100 qualified nursing staff (in the London area, England) working on either acute or PICU wards were used to gather data on appropriate and inappropriate referral to PICUs. Comments made during the course of the interviews were also collected and subjected to content analysis. Findings: There was evidence to support the hypothesis that acute ward staff considered patients suitable for PICU care at a lower level of risk than PICU staff thought appropriate. In comparison to acute ward nurses, those working in PICUs attended to a broader range of factors when considering suitability for admission to PICU. Appropriate reasons for transfer fell into five groups: risk to others; risk of intentional harm to self; risk of unintentional harm to self; therapeutic benefit from the PICU environment; and legitimate acute ward care problem. Inappropriate reasons for transfer fell into four groups: low risk to others and/or self; illegitimate acute admission care problems; patient belongs elsewhere; policy issues. Conclusion: The study opens up a range of issues not previously studied in relation to the use of PICUs and the intricate relationship of this use with the available acute care wards and other services. These findings and their implications for the care of acute and disturbed psychiatric patients are discussed

    Shift-encoded optically multiplexed imaging

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    In a multiplexed image, multiple fields-of-view (FoVs) are superimposed onto a common focal plane. The attendant gain in sensor FoV provides a new degree of freedom in the design of an imaging system, allowing for performance tradeoffs not available in traditional optical designs. We explore design choices relating to a shift-encoded optically multiplexed imaging system and discuss their performance implications. Unlike in a traditional imaging system, a single multiplexed image has a fundamental ambiguity regarding the location of objects in the image. We present a system that can shift each FoV independently to break this ambiguity and compare it to other potential disambiguation techniques. We then discuss the optical, mechanical, and encoding design choices of a shift-encoding midwave infrared imaging system that multiplexes six 15×15  deg FoVs onto a single one megapixel focal plane. Using this sensor, we demonstrate a computationally demultiplexed wide FoV video.United States. Air Force Office of Scientific Research (FA8721-05-C-0002
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