Feeding and the Equilibrium Feeder Animal Price-Weight Schedule, June 2005

The feeder animal price is a derivative in the sense that its value depends upon the price of animals for the consumption market. It also depends upon the biological growth technology and feed costs. Daily maintenance costs are of particular interest to the husbander because they can be avoided through accelerated feeding. In this paper, the optimal feeding path under equilibrium feeder animal prices is established. This analysis is used to gain a better understanding of feeding decisions, regulation in feedstuff markets, and the consequences of genetic innovations. It is shown that days on feed can increase or decrease with a genetic innovation or other improvement in feed conversion efficiency. The structure of comparative prices for feeder animals at different weights, the early slaughter decision, and equilibrium in feeder animal markets are also developed. Feeder animal prices can increase over a weight interval if biological feed efficiency parameters are low over the interval.

Stages of change, barriers, benefits, and preferences for exercise in RA patients: a cross-sectional study

OBJECTIVES: To determine the distribution of exercise stages of change in a rheumatoid arthritis (RA) cohort, and to examine patients' perceptions of exercise benefits, barriers, and their preferences for exercise. METHODS: One hundred and twenty RA patients who attended the Rheumatology Unit of a University Hospital were asked to participate in the study. Those who agreed were administered a questionnaire to determine their exercise stage of change, their perceived benefits and barriers to exercise, and their preferences for various features of exercise. RESULTS: Eighty-nine (74%) patients were finally included in the analyses. Their mean age was 58.4 years, mean RA duration 10.1 years, and mean disease activity score 2.8. The distribution of exercise stages of change was as follows: precontemplation (n = 30, 34%), contemplation (n = 11, 13%), preparation (n = 5, 6%), action (n = 2, 2%), and maintenance (n = 39, 45%). Compared to patients in the maintenance stage of change, precontemplators exhibited different demographic and functional characteristics and reported less exercise benefits and more barriers to exercise. Most participants preferred exercising alone (40%), at home (29%), at a moderate intensity (64%), with advice provided by a rheumatologist (34%) or a specialist in exercise and RA (34%). Walking was by far the preferred type of exercise, in both the summer (86%) and the winter (51%). CONCLUSIONS: Our cohort of patients with RA was essentially distributed across the precontemplation and maintenance exercise stages of change. These subgroups of patients exhibit psychological and functional differences that make their needs different in terms of exercise counselling.

Study of common database feeding with results coming from different analytical methods in the framework of illicit drugs chemical profiling

Analytical results harmonisation is investigated in this study to provide an alternative to the restrictive approach of analytical methods harmonisation which is recommended nowadays for making possible the exchange of information and then for supporting the fight against illicit drugs trafficking. Indeed, the main goal of this study is to demonstrate that a common database can be fed by a range of different analytical methods, whatever the differences in levels of analytical parameters between these latter ones. For this purpose, a methodology making possible the estimation and even the optimisation of results similarity coming from different analytical methods was then developed. In particular, the possibility to introduce chemical profiles obtained with Fast GC-FID in a GC-MS database is studied in this paper. By the use of the methodology, the similarity of results coming from different analytical methods can be objectively assessed and the utility in practice of database sharing by these methods can be evaluated, depending on profiling purposes (evidential vs. operational perspective tool). This methodology can be regarded as a relevant approach for database feeding by different analytical methods and puts in doubt the necessity to analyse all illicit drugs seizures in one single laboratory or to implement analytical methods harmonisation in each participating laboratory.

Productivities, preferences, and parental child care

We study the interplay of preferences and market productivities on parenting, and show the preferences, when identified, provide a better explanation of caring decisions than has, so far, been demonstrated in the literature. We qualify the standard finding the parental education in a key determinant of care by showing important interaction effects with marital homogamy. We find that homogamy has opposite effects on child care and couple specialization for high and low educated parents. Identification has been made possible by a unique couple-based time diary study for Denmark

Optimal Contracts, Adverse Selection, and Social Preferences: An Experiment

It has long been standard in agency theory to search for incentive-compatible mechanisms on the assumption that people care only about their own material wealth. However, this assumption is clearly refuted by numerous experiments, and we feel that it may be useful to consider nonpecuniary utility in mechanism design and contract theory. Accordingly, we devise an experiment to explore optimal contracts in an adverse-selection context. A principal proposes one of three contract menus, each of which offers a choice of two incentive-compatible contracts, to two agents whose types are unknown to the principal. The agents know the set of possible menus, and choose to either accept one of the two contracts offered in the proposed menu or to reject the menu altogether; a rejection by either agent leads to lower (and equal) reservation payoffs for all parties. While all three possible menus favor the principal, they do so to varying degrees. We observe numerous rejections of the more lopsided menus, and approach an equilibrium where one of the more equitable contract menus (which one depends on the reservation payoffs) is proposed and agents accept a contract, selecting actions according to their types. Behavior is largely consistent with all recent models of social preferences, strongly suggesting there is value in considering nonpecuniary utility in agency theory.

How accurate are surveyed preferences for public policies? Evidence from a unique institutional setup

Opinion polls are widely used to capture public sentiments on a varietyof issues. If citizens are unwilling to reveal certain policy preferences toothers, opinion polls may fail to characterize population preferences accurately.The innovation of this paper is to use unique data to measurebiases in opinion polls for a broad range of policies. I combine data on184 referenda held in Switzerland between 1987 and 2007, with postballotsurveys that ask for each proposal how the citizens voted. Thedifference between stated preferences in the survey and revealed preferences at the ballot box provides a direct measure of bias in opinion polls.I find that these biases vary by policy areas, with the largest ones occurring in policies on immigration, international integration, and votesinvolving liberal/conservative attitudes. Also, citizens show a tendencyto respond in accordance to the majority.

Turnout, political preferences and information: Experimental evidence from Perú

Electoral institutions that encourage citizens to vote are widely used around the world. Yet littleis known about the effects of such institutions on voter participation and the composition of the electorate.In this paper, I combine a field experiment with a change in Peruvian voting laws to identify theeffect of monetary (dis-)incentives on voting. Using the random variation in the fine for abstention andan objective measure of turnout at the individual level, I estimate the elasticity of voting with respectto cost to be -0.21. Consistent with the theoretical model presented, the reduction in turnout inducedby the reduction in the fine is driven by voters who (i) are in the center of the political spectrum, (ii)are less interested in politics, and (iii) hold less political information. However, voters who respondto changes in the cost of abstention do not have different preferences for policies than those who voteregardless of the cost. Further, involvement in politics, as measured by the decision to acquire politicalinformation, seems to be independent of the level of the fine. Additional results indicate that thereduction in the fine does not affect the incidence of vote buying, but increases the price paid for avote.

Study of the combined radial post-feeding dispersion of the blowflies Chrysomya megacephala (Fabricius) and C. albiceps (Wiedemann) (Diptera, Calliphoridae)

Blowflies use discrete and ephemeral substrates to feed their larvae. After they run out of food, the larvae begin to disperse in order to find adequate places for pupation or additional food sources, a process named post-feeding larval dispersion. Some important aspects of this process were studied in a circular arena allowing the combined radial post-feeding dispersion from the center of the arena of C. albiceps and C. megacephala larvae. To determine the location of each pupa, the arena was divided in 72 identical sections starting from the center. The distance from the center, the depth and weight of each pupa were evaluated. Statistical tests were done to verify the relation between weight, depth and distance for pupation. From the total an average of 976 larvae released (488 for each species) were collected considering both experiments 456 C. megacephala pupae and 488 of C. albiceps. This demonstrates that C. albiceps probably preyed on 32 C. megacephala larvae during post-feeding dispersion. The study of this dispersion process can be used to estimate the postmortem interval (PMI) of human cadavers in legal medicine.

Biased representation of homothetic preferences on homogeneous sets

In the homogeneous case of one-dimensional objects, we show that any preference relation that is positive and homothetic can be represented by a quantitative utility function and unique bias. This bias may favor or disfavor the preference for an object. In the first case, preferences are complete but not transitive and an object may be preferred even when its utility is lower. In the second case, preferences are asymmetric and transitive but not negatively transitive and it may not be sufficient for an object to have a greater utility for be preferred. In this manner, the bias reflects the extent to which preferences depart from the maximization of a utility function.

Do market conditions affect preferences? Evidence from experimental markets with excess supply and excess demand

We study whether people's preferences in an unbalanced market are affected by whether they are on the excess supply side or the excess demand side of the market. Our analysis is based on the comparison of behavior between two types of experimental gift exchange markets, which vary only with respect to whether first or second movers are on the long side of the market. The direction of market imbalance could influence subjects' motivation, as second movers, workers, might react differently to favorable actions by first movers, firms, in the two cases. Our data show strong deviations from the standard game-theoretic prediction. However, we only find secondary treatment effects. First movers are not more generous when they are in excess supply and second movers do not respond less favorably when they are in excess demand. Competition has only minor psychological effects in our data.

General preferences for consumption goods in the random matching model of commodity money

This paper generalizes the original random matching model of money byKiyotaki and Wright (1989) (KW) in two aspects: first, the economy ischaracterized by an arbitrary distribution of agents who specialize in producing aparticular consumption good; and second, these agents have preferences suchthat they want to consume any good with some probability. The resultsdepend crucially on the size of the fraction of producers of each goodand the probability with which different agents want to consume eachgood. KW and other related models are shown to be parameterizations ofthis more general one.

Are Americans' musical preferences more omnivores today?

Although we found a general trend favouring the omnivorousness thesis, as soon as we adjusted it to a set of structural factors and consumers tastes it was clear that this was caused by elitist inclusive omnivores who had increased the scope of their tastes. In general, younger cohorts were becoming less omnivorous, nevertheless, they were also becoming more educated and had greater to higher levels of inc ome, making the youth moreomnivorous. As expected, upscale consumers set limits on their popular taste: musicalgenres, whose audiences had educational levels below the mean profile were less preferredby upscale respondents. In spite of this, as time passed, some popular brows gained socialstatus.

Nymph developmental time and survivorship, adult longevity, reproduction and body weight of Dichelops melacanthus (Dallas) feeding on natural and artificial diets

The biology of nymphs and adults of the neotropical pentatomid, Dichelops melacanthus (Dallas), feeding on the natural foods, soybean, Glycine max (L.) Merrill immature pods, and corn, Zea mays L. immature seeds, and on an artificial dry diet, was studied in the laboratory. Nymph developmental time was shorter on the natural foods (ca. 21-22 days) than on the artificial diet (28 days), and most nymphs reached adulthood on the food plants (55% on soybean and 73% on corn) than on the artificial diet (40%). Fresh body weight at adult emergence was similar and higher for females raised as nymphs on the natural foods, compared to females from nymphs raised on the artificial diet; for males, weights were similar on all foods. Mean (female and male) survivorship up to day 20, decreased from 55% on soybean to 40% on corn, down to 0% on the artificial diet. Total longevity for females was higher on soybean, while for males was similar on all foods. About three times more females oviposited on soybean than on corn, but fecundity/female was similar on both foods. On the artificial diet, only one out of 30 females oviposited. Fresh body weight of adults increased significantly during the first week of adult life, and at the end of the 3rd week, weight gain was similar on all foods.

Voting with preferences over margins of victory

This paper analyzes a two-alternative voting model with the distinctive feature that voters have preferences over margins of victory. We study voting contests with a finite as well as an infinite number of voters, and with and without mandatory voting. The main result of the paper is the existence and characterization of a unique equilibrium outcome in all those situations. At equilibrium, voters who prefer a larger support for one of the alternatives vote for such alternative.The model also provides a formal argument for the conditional sincerity voting condition in Alesina and Rosenthal (1995) and the benefit of voting function in Llavador (2006). Finally, we offer new insights on explaining why some citizens may vote strategically for an alternative different from the one declared as the most preferred.

Social preferences and skill segregation

This paper shows that models where preferences of individuals dependnot only on their allocations, but also on the well-being of otherpersons, can produce both large and testable effects. We study theallocation of workers with heterogeneous productivities to firms. Weshow that even small deviations from purely selfish preferences leadsto widespread workplace skill segregation. That is, workers ofdifferent abilities tend to work in di¤erent firms, as long as theycare somewhat more about the utilities of workers who are close .