INVESTIGATING PREFERENCE HETEROGENEITY IN A REPEATED DISCRETE-CHOICE RECREATION DEMAND MODEL OF ATLANTIC SALMON FISHING

Estimating a demand system under the assumption that preferences are homogeneous may lead to biased estimates of parameters for any specific individual and significantly different expected consumer surplus estimates. This paper investigates several different parametric methods to incorporate heterogeneity in the context of a repeated discrete-choice model. The first is the classic method of assuming utility to be a function of individual characteristics. Second, a random parameters method is proposed, where preference parameters have some known distribution. Random parameters logit causes the random components to be correlated across choice occasions and, in a sense, eliminates IIA. Simulation noise is discussed. Finally, methods are proposed to relax the assumption that the unobserved stochastic component of utility is identically distributed across individuals. For example, randomization of the logit scale, which is a new method, allows noise levels to vary across individuals without the added burden of explaining the source using covariates. The application is to Atlantic salmon fishing, and expected compensating variations and changes in trip patterns are compared across the models for three policy-relevant changes in fishing conditions at the Penobscot River, the best salmon fishing site in Maine.Resource /Energy Economics and Policy,

Noncooperative Equilibria in Regional Environmental Policies When Plant Locations are Endogenous

A two-region model is presented in which an imperfectly competitive firm produces a good with increasing returns at the plant level, and in which shipping costs exist between the two markets. Production of the good causes local pollution, and regional governments can levy pollution taxes or impose environmental regulations. The firm decides. partly on the basis of these environmental policy variables, whether to maintain plants in both regions, serve both regions from a single plant or shut down. A non-cooperative equilibrium in regional environmental policies occurs when each region is choosing the environmental policy that maximizes its welfare given the environmental policy in the other region. Two types of harmful tax (regulatory) competitions are documented. If the disutility of pollution is high enough, each region will only want the polluting good produced in the other region and the two regions will likely compete by increasing their environmental taxes (standards) until the polluting firm is driven from the market. This is the case of "Not in my backyard". Alternatively, if the disutility from pollution is not as great, each region will realize that their welfare could decrease if their environmental policy causes the firm to not operate in their region. In this case, the regions will usually compete by undercutting each others pollution tax rates (environmental standards).

Environmental Policy When Market Structure and Plant Locations are Endo-genous

A two-region, two-firm model is developed in which firms choose the number and the regional locations of their plants. Both firms pollute and, in this context, market structure is endogenous to environmental policy. There are increasing returns at the plant level, imperfect competition between the "home" and the "foreign" firm, and transport costs between the two markets. These features imply that at critical levels of environmental policy variables, small policy changes cause large discrete jumps in a region's pollution and welfare as a firm closes or opens a plant, or shifts production for the foreign region from/to the home-region plant to/from a foreign branch plant. The implications for optimal environmental policy differ significantly from those suggested by traditional Pigouvian marginal analysis.

Construct validation of a non-exercise measure of cardiorespiratory fitness in older adults

<p>Abstract</p> <p>Background</p> <p>Cardiorespiratory fitness (CRF) is associated with a decreased risk of all-cause mortality but is rarely assessed in medical settings due to burdens of time, cost, risk, and resources. The purpose of this study was to test the construct validity of a regression equation developed by Jurca and colleagues (2005) to estimate CRF without exercise testing in community dwelling older adults.</p> <p>Methods</p> <p>Participants (n = 172) aged 60 to 80 years with no contraindications to submaximal or maximal exercise testing completed a maximal graded exercise test (GXT) and the submaximal Rockport 1-mile walk test on separate occasions. Data included in the regression equation (age, sex, body mass index, resting heart rate, and physical activity) were obtained via measurement or self-report. Participants also reported presence of cardiovascular conditions.</p> <p>Results</p> <p>The multiple R for the regression equation was .72, <it>p < .001 </it>and CRF estimated from this equation was significantly correlated with the MET value from the GXT (<it>r </it>= 0.66) and with CRF estimated from submaximal field testing (<it>r </it>= 0.67). All three CRF indices were significantly and inversely associated with reporting more cardiovascular conditions.</p> <p>Conclusions</p> <p>This research provides preliminary evidence that a non-exercise estimate of CRF is at least as valid as field test estimates of CRF and represents a low-risk, low-cost, and expedient method for estimating fitness in older adults.</p

A Unique Human-Fox Burial from a Pre-Natufian Cemetery in the Levant (Jordan)

New human burials from northern Jordan provide important insights into the appearance of cemeteries and the nature of human-animal relationships within mortuary contexts during the Epipalaeolithic period (c. 23,000–11,600 cal BP) in the Levant, reinforcing a socio-ideological relationship that goes beyond predator-prey. Previous work suggests that archaeological features indicative of social complexity occur suddenly during the latest Epipalaeolithic phase, the Natufian (c. 14,500–11,600 cal BP). These features include sedentism, cemeteries, architecture, food production, including animal domestication, and burials with elaborate mortuary treatments. Our findings from the pre-Natufian (Middle Epipalaeolithic) cemetery of ‘Uyun al-Hammam demonstrate that joint human-animal mortuary practices appear earlier in the Epipalaeolithic. We describe the earliest human-fox burial in the Near East, where the remains of dogs have been found associated with human burials at a number of Natufian sites. This is the first time that a fox has been documented in association with human interments pre-dating the Natufian and with a particular suite of grave goods. Analysis of the human and animal bones and their associated artefacts provides critical data on the nature and timing of these newly-developing relationships between people and animals prior to the appearance of domesticated dogs in the Natufian

Genome-Wide Patterns of Gene Expression during Aging in the African Malaria Vector Anopheles gambiae

The primary means of reducing malaria transmission is through reduction in longevity in days of the adult female stage of the Anopheles vector. However, assessing chronological age is limited to crude physiologic methods which categorize the females binomially as either very young (nulliparous) or not very young (parous). Yet the epidemiologically relevant reduction in life span falls within the latter category. Age-grading methods that delineate chronological age, using accurate molecular surrogates based upon gene expression profiles, will allow quantification of the longevity-reducing effects of vector control tools aimed at the adult, female mosquito. In this study, microarray analyses of gene expression profiles in the African malaria vector Anopheles gambiae were conducted during natural senescence of females in laboratory conditions. Results showed that detoxification-related and stress-responsive genes were up-regulated as mosquitoes aged. A total of 276 transcripts had age-dependent expression, independently of blood feeding and egg laying events. Expression of 112 (40.6%) of these transcripts increased or decreased monotonically with increasing chronologic age. Seven candidate genes for practical age assessment were tested by quantitative gene amplification in the An. gambiae G3 strain in a laboratory experiment and the Mbita strain in field enclosures set up in western Kenya under conditions closely resembling natural ones. Results were similar between experiments, indicating that senescence is marked by changes in gene expression and that chronological age can be gauged accurately and repeatedly with this method. These results indicate that the method may be suitable for accurate gauging of the age in days of field-caught, female An. gambiae

Diversity and Strain Specificity of Plant Cell Wall Degrading Enzymes Revealed by the Draft Genome of Ruminococcus flavefaciens FD-1

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