8,609 research outputs found
FARM-LEVEL RESPONSE TO AGRICULTURAL EFFLUENT CONTROL STRATEGIES: THE CASE OF THE WILLAMETTE VALLEY
This article examines economic incentives and other mechanisms to offset non-point source pollution from agriculture. A biophysical simulator to estimate technical relationships is linked to linear programming models for representative farms in the Willamette Valley of Oregon. The models are then optimized for profit maximization under alternative non-point pollution control policies. The results indicate that site-specific resource conditions and production possibilities greatly influence policy effectiveness and the cost of achieving pollution abatement. Nevertheless, some abatement is possible on all farms for relatively little cost.Environmental Economics and Policy,
Obituary: Arthur Cruickshank 1932 - 2011. A native Gondwanan, who studied the former continent's fossil tetrapods
Dr Arthur Richard Ivor Cruickshank died
on 4th December 2011, aged 79, in the
Borders General Hospital, Melrose, Scotland.
Arthur Cruickshank was part of the post-war
generation of palaeontologists who laid the
foundations on which today’s researchers
build. Appropriately for someone from
an expatriate Scots family living in Kenya,
much of his work was on the extinct reptiles
of the great southern palaeocontinent of
Gondwana
An assessment of acoustic contrast between long and short vowels using convex hulls
An alternative to the spectral overlap assessment metric (SOAM), first introduced by Wassink [(2006). J. Acoust. Soc. Am. 119(4), 2334–2350], is introduced. The SOAM quantifies the intra- and inter-language differences between long–short vowel pairs through a comparison of spectral (F1, F2) and temporal properties modeled with best fit ellipses (F1 × F2 space) and ellipsoids (F1 × F2 × duration). However, the SOAM ellipses and ellipsoids rely on a Gaussian distribution of vowel data and a dense dataset, neither of which can be assumed in endangered languages or languages with limited available data. The method presented in this paper, called the Vowel Overlap Assessment with Convex Hulls (VOACH) method, improves upon the earlier metric through the use of best-fit convex shapes. The VOACH method reduces the incorporation of “empty” data into calculations of vowel space. Both methods are applied to Numu (Oregon Northern Paiute), an endangered language of the western United States. Calculations from the VOACH method suggest that Numu is a primary quantity language, a result that is well aligned with impressionistic analyses of spectral and durational data from the language and with observations by field researchers
A Two-dimensional Spectral Analysis of Short Period Gravity Waves Imaged in the OI (557.7 nm) and Near Infrared OH Nightglow Emissions Over Arecibo, Puerto Rico
In January 1993 an extensive set of radar and optical data was gathered from various key sites around the world during a coordinated “10 Day Run” designed to investigate the coupled dynamic behavior of the upper atmosphere on a large, medium and small scale. As part of this campaign an all‐sky CCD imaging system was operated at Arecibo Observatory, Puerto Rico, to help quantify the response of the low latitude mesosphere‐thermosphere system to short period (\u3c1 hour) gravity waves. Measurements of the OI(557.7 nm) and near infrared OH nightglow emissions were made in conjunction with photometric and ISR radar soundings and revealed an abundance of small‐scale structure in the 80–100 km range. In this letter we apply two‐dimensional spectral analysis techniques to aid in the interpretation of a complex set of image data that consisted of two intersecting quasi‐monochromatic gravity wave patterns progressing on approximately orthogonal headings. An investigation of the spectral content and temporal evolution of these wave motions at each emission altitude is presented
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A wavelet based mammographic system
Mammography's role in the detection of breast cancer at early stages is well known. Although more accurate than other existing techniques, mammography still only finds 80 to 90 percent of breast cancers. It has been suggested that mammograms, as normally viewed, display only about 3% of the total information detected. The general inability to detect small tumors and other salient features within mammograms motivates our investigation of a system we call the Mammogram Display System (MDS). The core technology used for MDS image enhancement is the wavelet transform
Alexithymia, rash impulsiveness, and reward sensitivity in relation to symptoms of exercise dependence in physically active young adults
Objective Exercise dependence refers to excessive exercise accompanied by addiction-like symptoms such as craving, tolerance, withdrawal, impaired control, and disruption of life domains. The present study investigated whether personality traits linked to substance and behavioural addictions show similar associations with symptoms of exercise dependence. Method Alexithymia and two forms of impulsivity, rash impulsiveness and reward sensitivity, were assessed in relation to exercise dependence symptoms in a sample of 99 physically active young adult men and women. Results All three traits showed significant positive correlations with exercise dependence symptoms and were significant predictors of such symptoms in a hierarchical regression model. Alexithymia was the strongest predictor and fully mediated the contribution of rash impulsiveness according to bootstrapped mediation analysis. Conclusions Findings suggest similar associations of addiction-linked traits with symptoms of exercise dependence and are discussed in terms of potential mechanisms. KEY POINTS What is already known about this topic: (1) Exercise can become compulsive for some, with exercise dependence defined by addiction-like symptoms. (2) Alexithymia has been implicated as a risk factor for substance and behavioural addictions. (3) Two forms of impulsivity, rash impulsiveness and reward sensitivity, have been implicated as risk factors for substance and behavioural addictions. What this topic adds: (1) In physically active young adults, alexithymia was positively associated with symptoms of exercise dependence. (2) In physically active young adults, rash impulsiveness and reward sensitivity were positively associated with symptoms of exercise dependence. (3) Alexithymia fully explained the association of rash impulsiveness with exercise dependence symptoms
Sticklebacks show consistent prey-share hierarchies within but not between patchy and sequential prey distributions
This work was supported by the School of Biology’s Experimental Research Project (BL4201) program, (module BL4201: Experimental Research Project) at the University of St Andrews, UK.When animals compete, hierarchies can emerge. If the outcome of competition under different conditions is dependent upon different sets of attributes, then we may expect to see hierarchies that are domain-specific, rather than domain general. We tested this idea by comparing prey share hierarchies within shoals of sticklebacks Gasterosteus aculeatus as they foraged for patchily-distributed or for drifting prey. We found that prey share was correlated across pairs of patch- and pairs of drift-foraging trials, but not between the two conditions, suggesting that separate repeatable but independent prey share hierarchies arise for each for each type of prey distribution. We discuss possible underlying mechanisms and ecological implications of this finding.PostprintPeer reviewe
Interactive wavelet processing and techniques applied to digital mammography
We present an interactive scheme for processing of digital mammograms relying upon a steerable dyadic wavelet transform. Coefficients of the translation and rotation-invariant transform are interactively processed before an inverse transform is applied. Analysis is carried out at dyadic scales and along arbitrary orientations. Local orientation is computed at each level of scale and spatial position and formulated into criteria for including or excluding specific orientations for contrast enhancement and enhancing locally radiating structures. Transform coefficients that were selected for contrast enhancement are modified by a piecewise linear enhancement function. The presented scheme is flexible enough to enable efficient position, scale, and orientation based interactive processing and analysis
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