The Structure and Freezing of fluids interacting via the Gay-Berne (n-6) potentials

We have calculated the pair correlation functions of a fluid interacting via the Gay-Berne(n-6) pair potentials using the \PY integral equation theory and have shown how these correlations depend on the value of n which measures the sharpness of the repulsive core of the pair potential. These results have been used in the density-functional theory to locate the freezing transitions of these fluids. We have used two different versions of the theory known as the second-order and the modified weighted density-functional theory and examined the freezing of these fluids for $8 \leq n \leq 30$ and in the reduced temperature range lying between 0.65 and 1.25 into the nematic and the smectic A phases. For none of these cases smectic A phase was found to be stabilized though in some range of temperature for a given $n$ it appeared as a metastable state. We have examined the variation of freezing parameters for the isotropic-nematic transition with temperature and $n$. We have also compared our results with simulation results wherever they are available. While we find that the density-functional theory is good to study the freezing transitions in such fluids the structural parameters found from the \PY theory need to be improved particularly at high temperatures and lower values of $n$.Comment: 21 Pages (in RevTex4), 6 GIF and 4 Postscript format Fig

Male remating in Drosophila ananassae: evidence for interstrain variation for remating time and shorter duration of copulation in second mating

ABSTRACT—In Drosophila ananassae, male remating was studied using ten mass culture stocks which were initiated from flies collected from different geographic localities. Male remating occurs at a high fre-quency and varies within narrow limits (84–96 percent) in different strains. Interestingly, male remating time (in min) varies from 7.41 (Bhutan) to 21.59 (PAT) in different strains and the variation is highly significant. Further, the results also show that males copulate for shorter duration during second mating. This is the first report in the genus Drosophila which provides evidence for interstrain variations for male remating time as well as for shorter duration of copulation during second mating as compared to first mating in D. ananassae

Female remating in Drosophila ananassae: bidirectional selection for remating speed

In Drosophila ananassae, artificial selection was carried out for fast and slow remating speed for 10 generations. Response to selection resulted in rapid divergence in remating time in each of two replicates of both fast and slow lines. There were significant differences in mean remat-ing time in females among fast, slow, and control lines. Regression coefficients for both fast and slow lines are significantly different from zero. The realized heritability over 10 genera-tions of selection is from 0.26 to 0.33 for two replicates of fast line and from 0.23 to 0.27 for two replicates of slow line. These findings suggest that female remating time in D. ananassae is under polygenic control. Remating frequency of females showed a correlated response in both fast and slow lines. At generation 10, correlated response to selection was also investigated. Mating propensity of D. ananassae of fast and slow lines was observed in an Elens-Wattiaux mating chamber. Fifteen pairs per test showed that on the average, the fast lines (11.20, 11.60) were more successful in mating than those of slow (6.40, 5.60) and control (8.00) lines. Pro-ductivity of once-mated females was measured in terms of number of progeny produced per fe-male and the results of productivity analysis indicate that females of fast lines (157.83, 130.83) produced more progeny compared with slow (72.70, 85.83) and control (109.23) lines

Female remating in Drosophila ananassae: effect of density on female remating frequency

Drosophila ananassae, a cosmopolitan and domestic species, is largely cir-cumtropicalin distribution and belongs to the ananassae species complex of the ananassae subgroup of the melanogaster species group. In the present study, experiments were conducted to investigate the effect of density on fe-male remating frequency by employing different wild-type and mutant strains of D. ananassae. Two experimental designs, i.e., 2-h daily observation and continuous confinement, were used. The results show that there is significant dependence of remating frequency on density in all strains tested under both experimental designs except in a wild-type strain (Bhutan), which shows no dependence of remating frequency on density under 2-h daily observation de-sign. This finding provides evidence that density may increase the frequency of female remating in D. ananassae

Delays and Cost Overruns in Infrastructure Projects -- An Enquiry into Extents, Causes and Remedies

Media reports abound on instances of prolonged delays and excessive cost overruns in infrastructure projects. Only a small number of projects get delivered in time and within the budget. Examples of successful project implementation, like construction of the Delhi Metro Rail, are few and appear only far in between. Indeed, the problem of time and cost overruns in India is widespread and severe. Yet, very few empirical studies exist on the subject. Even rarer are the studies based on completed projects. As a result, the extents as well as the causes behind delays and cost overruns have remained under-researched. This study investigates the various issues related to delays and cost overruns in publically funded infrastructure projects. The following questions are posed and answered -- How common and how large are the time and the cost overruns? What are the essential causes behind these delays and cost overruns? Are the underlying causes statistically significant? Are Contractual and Institutional failures among the significant causes? What are the policy implications for planning, development and implementation of infrastructure projects? The study is based on, by far, the largest dataset of 894 projects from seventeen infrastructure sectors. Among other results, it shows that the contractual and the institutional failures are economically and statistically significant causes behind cost and time overruns.Delays, Cost Overruns, Time Overruns, Infrastructure, Projects, Causes, Contractual Failures, Organizational Failures, Institutional Failures

On the Existence and Efficiency of Equilibria Under Liability Rules

While the focus of mainstream economic analysis of liability rules remains on negligence liability, recently some legal scholars have argued for the sharing of liability. In this paper, our first objective is contribute to the debate regarding the desirability of the sharing of liability for the accident loss. To this end, we study the implications of various approaches toward liability assignment for the existence and efficiency of equilibria. In particular, we analyze the proposal of Calabresi and Cooper (1996). Contrary to what is suggested in the literature, we show that the sharing of liability when parties are either both negligent or both non-negligent does not threaten the existence of equilibria. Moreover, it does not dilute the incentives for the parties to take the due care. Our second objective is to extend the efficiency analysis beyond Shavell (1980, 1987) and Miceli (1997), to search for the second-best liability rules. We show that each of the standard liability rules fails to be efficient even from a second-best perspective. Furthermore, we show that second-best efficiency requires loss sharing between non-negligent parties. As corollaries to our main results, we reexamine some of the existing claims regarding the existence and efficiency of equilibria under liability rules.

On the Existence and Efficiency of Equilibria under Liability Rules

While focus of the mainstream analysis of liability rules has been on negligence based liability, some recent works have recommended sharing of liability between the parties involved in an accident. In this paper, we study the implications of various approaches to liability assignment for the existence and efficiency of equilibria under liability rules. Contrary to what is suggested in the literature, we show that the sharing of liability when parties are either both negligent or both non-negligent does not threaten the existence of equilibria. Moreover, it does not dilute the incentive for the parties to take the due care. Also, we extend the analysis to search for the second-best liability rules; since in view of Shavell (1987) no liability rule can achieve the first best outcome. We show that each of the standard liability rules fails to be efficient even from from a second best perspective. We show that second best efficiency requires loss sharing between non-negligent parties. As implications of our main results, we reexamine some of the existing claims regarding the existence and efficiency of equilibria under liability rules.

Characterization of Efficient Product Liability Rules: When Consumers are Imperfectly Informed

Product liability has acquired immense importance in the last 50 years. Various studies show that when consumers are imperfectly informed about the product related risk, the market mechanism will not lead to an efficient outcome and tort liability is required for economic efficiency. Many product-caused injuries are governed by liability rules. In this paper efficiency properties of the entire class of product liability rules when consumers are imperfectly informed about the product related risk are studied in a unified framework. A necessary and sufficient condition for efficiency of a product liability rule is derived. The analysis is carried out in a somewhat more general framework.Product Risk, total accident costs, efficient product liability rules, social benefits, negligent consumer's liability, imperfect information, Nash equilibrium.

Risk, Informational Asymmetry and Product Liability; An enquiry into conflicting objectives

Risky products cause two types of costs for society; the accident costs and the insurance costs. Liability rules allocate these costs between the parties involved. The expansion in the scope of product liability over the past thirty years has increased the cost of third-party liability insurance. However, the economic analysis of product liability rules has, generally, focused on only the accident costs. Some recent works have suggested that there is a strict trade-off involved when it comes to minimizing the accident costs and the insurance costs. In this paper, we have extended the economic analysis by considering both types of costs. An efficiency characterization of product liability rules has been provided by assuming that consumers lack in the knowledge about the risk. We have shown that even when consumers misperceive the product risk, it possible to achieve efficiency with respect to the insurance costs as well as the care levels.Product liability, informational asymmetry, accident costs, insurance costs, Nash equilibrium, economic efficiency