8,874 research outputs found
Is the yield curve a useful Information variable for the Eurosystem?
The focus of this paper is on the use of the yield curve in monetary policy making. Theoretical arguments and a multi-country empirical analysis with an explicit focus on the euro area suggest the need for caution in case the Eurosystem uses the yield curve as an information variable for monetary policy, because multiple theoretical explanations exist for an observed movement in the yield curve, suggesting that policy reactions cannot be prescribed unambiguously. In addition, the empirical analysis shows that, in contrast with earlier findings of, for example, Hardouvelis (1994) and Bernard and Gerlach (1996), the information content of the yield curve is fairly limited. For the individual European countries participating in the Eurosystem as well as for the euro area as a whole, the yield spread possesses only very limited information relating to future movements in the inflation rate and output growth, over-and-above the information contained in the history of the latter variables. JEL Classification: E43, E52
What are Firms? Evolution from Birth to Public Companies
We study how firm characteristics evolve from early business plan to initial public offering to public company for 49 venture capital financed companies. The average time elapsed is almost 6 years. We describe the financial performance, business idea, point(s) of differentiation, non-human capital assets, growth strategy, customers, competitors, alliances, top management, ownership structure, and the board of directors. Our analysis focuses on the nature and stability of those flrIn attributes. Firm business lines remain remarkably stable from business plan through public company. Within those business lines, non-human capital aspects of the businesses appear more stable than human capital aspects. In the cross-section, firms with more alienable assets have substantially more human capital turnover.Theory of the firm; Entrepreneurship; Venture capital; Firm life cycle
8. Limitations of Using Student-Achievement Data for Career-Ladder Promotions and Merit-Pay Decisions
A study of U.S. school districts conducted 70 years ago reported that 48% of the districts sampled used merit pay (Evendon, 1918). Since then, the quantity as well as quality of teacher-compensation systems has fluctuated markedly (for details, see Cohen & Murnane, 1985; Murnane & Cohen, 1986; Porwoll, 1979). At present, 29 states are implementing large-scale teacher-incentive programs (a.k.a. career ladder, merit pay, pay for performance), funding local plans, piloting testing models, or using state board of education or legislative mandates to develop programs for teachers and administrators (Southern Regional Education Board, 1986) The status of these programs is summarized in Table 8.1.
Teacher performance is at the core of all of the programs in operation or those being considered. Determining who will receive the pay bonuses, which typically range from 3,000 per year, or be promoted up the career-ladder hinges on the methods used to evaluate teacher performance. The current trend in measurement procedures is to deemphasize supervisory ratings by the building principal and instead to emphasize peer evaluation, classroom observation, student-achievement outcomes, and questionnaire data from principals, teachers, and students (for details, see Southern Regional Education Board, 1986).
Use of Student·Achievement Data
One particular procedure that seems to be gaining acceptance increasingly by legislators and the professionals who are designing the programs is the use of student-achievement data (d. Robinson, 1983; 1984). These data provide information different from the other measurement tools previously noted. Where classroom observation and ratings by principals, teachers, and students measure a teacher\u27s behavior on the job, student achievement relates to the outcomes of that behavior. That is, the former methods are direct measures of teacher performance; the latter is an indirect measure. Student outcomes are perceived as evidence of a teacher\u27s effectiveness. Because superior teacher performance is the criterion in teacher-incentive programs, the psychometric issue becomes how best to measure that performance-use direct measures, indirect measures, or a combination of both.
Teacher-incentive programs that rely on student-achievement gains have been referred to as new style merit pay (Bacharach, Lipsky, & Shedd, 1984), as opposed to old style merit pay, which bases teacher pay bonuses on principals\u27 evaluations. In 1983, a national survey of merit-pay programs reported that nine school districts in seven states (Arizona, New Hampshire, North Carolina, Oklahoma, South Dakota, Texas, Utah) used student-test scores as evaluative criteria in determining merit pay for classroom teachers (Calhoun & Protheroe, 1983). In all but two of the districts (Dallas and Houston) student achievement served as the only evidence of teacher performance. Today student achievement is a criterion of teacher performance in one third of all statewide teacher incentive/school incentive/career ladder programs. Those programs have been fully implemented in four states (Florida, South Carolina, Tennessee, Utah), are at the pilot stage in four states (Arizona, Kentucky, Maine, South Carolina), and are under development in three states (Alabama, Florida, Georgia). A school incentive program based on student achievement is also under consideration in Alaska, and several career-ladder or merit-pay programs based on student performance have been implemented by local districts (e.g ., Campbell County and Danville, Virginia)
ENVIRONMENTAL VARIATION AND SEXUAL SELECTION IN THE MOUNTAIN BLUEBIRD (SIALIA CURRUCOIDES)
Sexual selection acts on traits that increase mating success, either through mating preferences or intrasexual competition for access to mates. For traits to be honest, we expect sexually selected traits to reflect individual condition at the time of trait development. Furthermore, when sexual selection operates through mating preferences, we also expect traits to indicate benefits (direct or indirect) that females receive for exercising their preference. If sexual selection acts through differential success in intrasexual contests over mates, we expect traits to indicate resource holding potential, or fighting ability. These links between individual condition, trait quality, and performance maintain honesty, because high condition individuals have high quality traits, and conspecifics can therefore use information from sexually selected traits when entering contests or choosing between prospective mates.
Based on the above logic, we expect sexually selected traits to be consistently and positively related to performance. However, individuals may differ in their sensitivity to environmental variation such that sexually selected traits are not always honest indicators of individual condition, benefits to females or offspring, or competitive ability. Environmental variation could affect trait honesty if individuals vary in their ability to respond to environmental variation. For example, trait honesty may disappear in poor environments, if individuals with highly developed sexually selected traits only perform well in high quality environments. Alternatively, individuals with more elaborate traits may be more adept at responding to environmental challenge, and trait honesty could increase when environmental conditions are poor.
For my dissertation I examined variation in trait development and honesty under varying conditions in the mountain bluebird, Sialia currucoides. Mountain bluebirds display sexually dimorphic UV-blue coloration, and males with more intense coloration sire more offspring at their own nest and at other nests through extra-pair fertilizations. However, it is unclear what benefits and costs receivers experience when using this trait to asses mates or rivals, and what processes regulate the development of this sexually selected trait. Therefore, in chapter one I explored the function of this signal during agonistic contests for territories. I performed simulated territorial intrusions to understand whether male aggressive behavior was related to his coloration. I also measured food availability to determine if males with more intense coloration obtained higher quality territories. Overall, my results provide evidence for the function of this signal during agonistic contests. Furthermore, while a single aggressive behavior (number of attacks) was repeatable across the egg laying period, my integrated metric of aggression, which accounted for many aggressive behaviors and was related to male coloration, was not. Lastly, I found that males with more saturated coloration obtained territories with greater insect abundance.
In chapter two, I performed an experiment to understand the mechanisms of condition dependence of blue coloration. Individuals may vary in their sensitivity to environmental variation during trait development; such high condition individuals preserve trait quality during environmental challenge while poor condition individuals do not. Martin et al. (2011) suggest that endocrine systems are an important mediator of phenotypic variation because hormones both respond to environmental conditions and regulate internal response and resulting phenotype. The hormone corticosterone (CORT) is released by the adrenal glands in response to challenge to divert resources towards self-preservation. A rapid, transient increase in CORT can help individuals to survive challenging situations. However, prolonged or frequent CORT secretion can cause damage to other physiological systems and potentially decrease fitness. For example, CORT-implanted white crowned sparrows abandon their high-elevation breeding territories and retreat to low elevations during storms. This increases survival but decreases reproductive success. Also, CORT-implanted male song sparrows increase fat stores, but are less likely to respond aggressively to a simulated territorial intrusion. These links between environmental conditions and potential fitness consequences make CORT an ideal regulator of sexually selected traits.
To this end, I brought 14 hatch year mountain bluebirds into captivity to study how individual variation in CORT physiology during resource limitation predicted coloration. I wanted to understand whether CORT predicted blue coloration when resources were abundant, limiting, or both. I found that when birds were food limited, variation in CORT levels increased. Furthermore, CORT and coloration were negatively associated in my food limitation treatment, as predicted if poor condition males mount larger stress responses, but this association disappeared when birds were given ad lib food. I also measured feather structure variables to determine how coloration was related to feather quality and feather performance (measured as resistance to airflow) across my resource availability treatments. I found that the component of feather structure that was related to coloration (barbule density) was sensitive to CORT only when resources were limiting. Conversely, the feather structure variable that determined feather performance (interbarb distance) was not sensitive to CORT in either treatment and did not predict feather coloration. These results indicate that feather coloration in bluebirds is only sensitive to variation in physiology when resources were limiting, and that this was mirrored by concurrent changes in condition-sensitive feather structure. However, feather performance was not sensitive to individual variation in physiology or variation in environmental conditions.
While chapters one and two demonstrated that blue coloration is condition dependent and related to aggressive behavior, male bluebirds still provide a significant amount of parental care. This means that females may be using coloration to select mates and obtain benefits for themselves and their offspring. In chapter three, I examined the effect of environmental variation on the relationship between bluebird coloration and direct benefits to females, expressed as offspring quality (nestling mass). Three years of data on free-living bluebirds suggests that the relationship between male coloration and nestling mass varied across years and between broods. In some contexts, more elaborate males had heavier nestlings, while in other contexts they raised the lightest nestlings. I found that this variation was not driven by resource abundance, but instead appeared due to changes in optimal reproductive effort. When average nestling mass at my study site was higher, bluer males raised heavier nestlings than they did when average nestling mass was lower. This variation in nestling mass occurred independently of resource availability.
Overall, these results demonstrate that the honesty of blue coloration varies across environmental contexts. While coloration is positively related to aggressive behavior, males vary in their sensitivity to resource limitation, and blue coloration does not consistently predict direct benefits in the wild. My data indicate that the process of sexual selection is context-dependent, and sexually selected traits vary in the extent to which they predict individual performance and quality
Re-interpreting sub-group inequality decompositions
The authors propose a modification to the conventional approach of decomposing income inequality by population sub-groups. Specifically, they propose a measure that evaluates observed between-group inequality against a benchmark of maximum between-group inequality that can be attained when the number and relative sizes of groups under examination are fixed. The authors argue that such a modification can provide a complementary perspective on the question of whether a particular population breakdown is salient to an assessment of inequality in a country. As their measure normalizes between-group inequality by the number and relative sizes of groups, it is also less subject to problems of comparability across different settings. The authors show that for a large set of countries their assessment of the importance of group differences typically increases substantially on the basis of this approach. The ranking of countries (or different population groups) can also differ from that obtained using traditional decomposition methods. Finally, they observe an interesting pattern of higher levels of overall inequality in countries where their measure finds higher between-group contributions.Inequality,Poverty Impact Evaluation,Governance Indicators,Rural Poverty Reduction,Services&Transfers to Poor
Is Proprioceptive Training Effective in Reducing the Recurrence of Ankle Sprains among Athletes?
OBJECTIVE: The objective of this systematic review is to determine whether or not proprioceptive training is effective in reducing the recurrence of ankle sprains among athletes
Past trauma and future choices: Differences in discounting in low-income, urban African Americans
AbstractBackgroundExposure to traumatic events is surprisingly common, yet little is known about its effect on decision making beyond the fact that those with post-traumatic stress disorder are more likely to have substance-abuse problems. We examined the effects of exposure to severe trauma on decision making in low-income, urban African Americans, a group especially likely to have had such traumatic experiences.MethodParticipants completed three decision-making tasks that assessed the subjective value of delayed monetary rewards and payments and of probabilistic rewards. Trauma-exposed cases and controls were propensity-matched on demographic measures, treatment for psychological problems, and substance dependence.ResultsTrauma-exposed cases discounted the value of delayed rewards and delayed payments, but not probabilistic rewards, more steeply than controls. Surprisingly, given previous findings that suggested women are more affected by trauma when female and male participants’ data were analyzed separately, only the male cases showed steeper delay discounting. Compared with nonalcoholic males who were not exposed to trauma, both severe trauma and alcohol-dependence produced significantly steeper discounting of delayed rewards.ConclusionsThe current study shows that exposure to severe trauma selectively affects fundamental decision-making processes. Only males were affected, and effects were observed only on discounting delayed outcomes (i.e. intertemporal choice) and not on discounting probabilistic outcomes (i.e. risky choice). These findings are the first to show significant differences in the effects of trauma on men's and women's decision making, and the selectivity of these effects has potentially important implications for treatment and also provides clues as to underlying mechanisms.</jats:sec
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Adenovirus E1A Activation Domain Regulates H3 Acetylation Affecting Varied Steps in Transcription at Different Viral Promoters.
How histone acetylation promotes transcription is not clearly understood. Here, we confirm an interaction between p300 and the adenovirus 2 large E1A activation domain (AD) and map the interacting regions in E1A by observing colocalization at an integrated lacO array of fusions of LacI-mCherry to E1A fragments with YFP-p300. Viruses with mutations in E1A subdomains were constructed and analyzed for kinetics of early viral RNA expression and association of acetylated H3K9, K18, K27, TBP, and RNA polymerase II (Pol II) across the viral genome. The results indicate that this E1A interaction with p300 is required for H3K18 and H3K27 acetylation at the E2early, E3, and E4 promoters and is required for TBP and Pol II association with the E2early promoter. In contrast, H3K18/27 acetylation was not required for TBP and Pol II association with the E3 and E4 promoters but was required for E4 transcription at a step subsequent to Pol II preinitiation complex assembly.IMPORTANCE Despite a wealth of data associating promoter and enhancer region histone N-terminal tail lysine acetylation with transcriptional activity, there are relatively few examples of studies that establish causation between these histone posttranslational modifications and transcription. While hypoacetylation of histone H3 lysines 18 and 27 is associated with repression, the step(s) in the overall process of transcription that is blocked at a hypoacetylated promoter is not clearly established in most instances. Studies presented here confirm that the adenovirus 2 large E1A protein activation domain interacts with p300, as reported previously (P. Pelka, J. N. G. Ablack, J. Torchia, A. S. Turnell, R. J. A. Grand, J. S. Mymryk, Nucleic Acids Res 37:1095-1106, 2009, https://doi.org/10.1093/nar/gkn1057), and that the resulting acetylation of H3K18/27 affects varied steps in transcription at different viral promoters
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