Bulk elastic properties of chicken embryos during somitogenesis

We present measurements of the bulk Young's moduli of early chick embryos at Hamburger-Hamilton stage 10. Using a micropipette probe with a force constant k ~0.025 N/m, we applied a known force in the plane of the embryo in the anterior-posterior direction and imaged the resulting tissue displacements. We used a two-dimensional finite-element simulation method to model the embryo as four concentric elliptical elastic regions with dimensions matching the embryo's morphology. By correlating the measured tissue displacements to the displacements calculated from the in-plane force and the model, we obtained the approximate short time linear-elastic Young's moduli: 2.4 ± 0.1 kPa for the midline structures (notocord, neural tube, and somites), 1.3 ± 0.1 kPa for the intermediate nearly acellular region between the somites and area pellucida, 2.1 ± 0.1 kPa for the area pellucida, and 11.9 ± 0.8 kPa for the area opaca

EXPANDING GIS ANALYSES TO MONITOR AND ASSESS NORTH AMERICAN MOOSE DISTRIBUTION AND DENSITY

Development of long-term geographic information system (GIS) databases of species densities and distributions, combined with biological, ecological, and management-related metrics, can help guide research and management strategies. Here we summarize 3 decades of North American moose (Alces alces) population and harvest densities collected at the management unit scale for the years 1980, 1990, 2000, and 2010. A summary analysis of these data indicates that moose have both expanded and contracted along their southern range boundary in recent decades - including the Prairie Provinces and states, and a portion of the northeastern United States. A narrow band of relatively stable and high-density moose populations extends from central Alaska across the Prairie Provinces and east to the Maritime Provinces and upper northeastern states. Distributions in 2010 indicate that moose now occupy an area > 9,492,000 km2 in North America. We also identified that a core range of boreal habitat, only 30% of the occupied range across the continent, supports 89% of the estimated 1 million moose in North America. Time-series analyses can offer a simple and cost-effective approach to monitor the status of moose populations in North America, and might be particularly insightful given the current and predicted future influences of climate change on moose. Other analyses might address population dynamics, habitat, environmental constraints, and harvest management, among other issues. We encourage jurisdictions to cooperate strategically in implementing and coordinating GIS analyses to monitor, assess, and manage the North American moose population

Military Retention Incentives: Evidence from the Air Force Selective Reenlistment Bonus

The limited lateral entry and rigid pay structure for U.S. military personnel present challenges in retaining skilled individuals who have attractive options in the civilian labor market. One tool the services use to address this challenge is the Selective Reenlistment Bonus (SRB), which offers eligible personnel with particular skills a substantial cash bonus upon reenlistment. However, the sequential nature of the bonus offer and reenlistment process limits the ability to adjust manpower quickly, raising interest in research that estimates the effect of the SRB on retention. While this literature has acknowledged challenges including potential endogeneity of bonus levels, attrition, and reenlistment eligibility, many studies do not address these concerns adequately. This paper uses a comprehensive panel data set on Air Force enlisted personnel to estimate the effect of the SRB on retention rates. We exploit variation in bonus levels within skill groups, control for civilian labor market conditions, and model reenlistment eligibility to avoid common assumptions that lead to biased impact estimates. We find substantial heterogeneity in the effect of the bonus, with the largest effects on first-term service members and those whose skills have not historically received a substantial bonus. We also find evidence that the bonus affects the timing of reenlistment decisions in addition to their frequency

Track D Social Science, Human Rights and Political Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

Cheating as a function of expectancy, internal-external control, and type of task

Includes bibliographical references.Cheating in the classroom is the cause of much concern for both teachers and students. Therefore, the purpose of the present study was to investigate the relationship between several personality variables and cheating behavior in order to discover some possible reasons for its occurrence. The hypotheses for the study were derived from Rotter's Social Learning Theory. According to Social Learning Theory, the potentiality for a behavior to occur in a particular situation is a function of expectancy and reinforcement value. Expectancy refers to the probability held by a person that the behavior will lead to a reinforcement in the situation, and reinforcement value refers to a person's preference for one reinforcement relative to another reinforcement which is also available to him in the situation. Social Learning Theory conceptualizes maladaptive behavior as occurring under conditions of low expectancy and high reinforcement value; that is, when a person has a low expectation of obtaining a reinforcement that he desires. On the basis of this conceptualization of maladaptive behavior, two hypotheses were proposed concerning the occurrence of cheating which was the maladaptive behavior of interest in the present study. The first hypothesis proposed that cheating will occur more frequently when expectancy for success is low than when expectancy for success is high. The second hypothesis proposed that cheating will occur more frequently on a test with high reinforcement value than on a test with low reinforcement value. The other two hypotheses investigated in the present study involved the internal-External control construct which was developed within the framework of Social Learning Theory. On the basis of previous research which suggested a relationship between the Internal-External control construct and cheating, it was hypothesized that cheating will occur more frequently among externally oriented people than among internally oriented people and that externally oriented people will be more likely than internally oriented people to deny having cheated. The methodology employed in the present study was as follows. The subjects were administered the first required test in a course, and the grade each subject received on this test was used as an index of his expectancy for success on a subsequent test in the course. Six weeks later, the subjects took the second required course test which was considered to have high reinforcement value since it was directly related to the goal of passing the course. After taking the second required course test, the subjects were administered a general information "intelligence" test which was considered to have low reinforcement value since it had no perceptible relation to future success in the course. A week after taking the second course test and the intelligence test, the subjects were asked to score both of these tests themselves. However, unknown to the subjects, both tests had been scored by the experimenter. If the score recorded by a subject was two or more points greater than the score recorded by the experimenter, the subject was said to have cheated. If the score recorded by a subject was the same as the score recorded by the experimenter, the subject was said to have not cheated. The results were as follows. First, subjects with a low expectancy for success resulting from a low grade on the first course test cheated in significantly greater numbers on the second course test than subjects with a high expectancy for success resulting from a high grade on the first course test. In addition, subjects whose grade and expectancy were between the above two extreme expectancy groups fell between these two extreme groups with respect to the number who cheated. Second, more subjects cheated on the test with high reinforcement value than on the test with low reinforcement value. Third, the number of externally oriented subjects who cheated was, in general, greater than the number of internally oriented subjects who cheated. However, there was no difference between the number of externally oriented subjects and the number of internally oriented subjects who denied having cheated. Finally, some sex differences were found with respect to cheating, but these differences depended on the type of test. Possible implications of the above results were discussed and further research in the area was suggested.M.A. (Master of Arts

How Deployments

This PDF document was made available from www.rand.org as a public service of the RAND Corporation. Jump down to document6 The RAND Corporation is a nonprofit research organization providing objective analysis and effective solutions that address the challenges facing the public and private sectors around the world. Support RAND Purchase this documen

The effect of deployment on first- and second-term re-enlistment in the US active duty force

Why should deployment affect re-enlistment? In our model, members enter the military with naive beliefs about deployment and use actual deployment experience to update their beliefs and revise their expected utility of re-enlisting. Empirically, re-enlistment is related to the type and number of deployments, consistent with the learning model. Non-hostile deployment increases first-term re-enlistment but hostile deployment has little effect except for the Army, where the effect is positive. Both types increase second-term re-enlistment. Interestingly, first-term members with dependants tend to respond to deployment like second-term members. In addition, deployment acts directly to affect re-enlistment, not indirectly through time to promotion.Deployment, Re-enlistment, Bayesian learning, Expected utility, JEL codes: J22, J24, J28,

Perspectives on U.S. Competitiveness in Science and Technology

For people interested in the continued dominance of the United States in the worlds of science and technology there is one crucial question: "Is the United States in danger of losing its competitive edge of science and technology?" This was the primary question on the minds of those convened by the RAND Corporation to a meeting in November of 2006. At the request of the Under Secretary of Defense for Personnel and Readiness, RAND brought together experts in academia, government and the private sector to this meeting. The papers presented at this conference addressed issues such as science policy, globalization, the rise of Asia, and technology diffusion. Edited by Titus Galama and James Hosek, this 162-page document presents these various papers, and for persons interested in the potential policy implications of these matters, this report will be most timely and helpful