7,177 research outputs found
Water temperature during winter may control striped bass recruitment during spring by affecting the development time of copepod nauplii
Get PDFStriped bass (Morone saxatilis) are anadromous fish that support an important fishery along the east coast of North America. In Chesapeake Bay, strong juvenile recruitment of striped bass can occur when larvae overlap with high concentrations of their zooplankton prey, but the mechanisms fostering the temporal overlap are unknown. Here, the influence of winter temperature on the peak abundances of a key prey, Eurytemora carolleeae, was estimated with a temperature-dependent developmental model. The role of these peaks in regulating striped bass recruitment was explored in three nursery areas: upper Chesapeake Bay, Choptank River, and Patuxent River. Model results indicated that cold winters delay the timing and increase the size of peak E. carolleeae spring abundance. When the model output was used in regression relationships with striped bass juvenile recruitment and freshwater discharge, the regression models explained up to 78% of annual recruitment variability. Results suggests that cold, wet winters could increase the chance of a match between striped bass larvae and high concentrations of their prey. This mechanistic link between winter temperatures and striped bass production, acting through prey dynamics, could further understanding of fish recruitment variability and indicates that warmer winters could negatively affect some striped bass populations
Individual difference correlates of continuing versus ceasing musical participation
Get PDFWhile researchers have begun to examine how social and emotional investment in music is related to psychological well‐being, very little research has considered how best to promote life-long participation in music across the lifespan. One particular gap in the existing literature concerns how and why individuals continue to participate or, instead, cease their participation in musical activities. The current research adopted a social psychological approach to quantitatively examine the differences between 383 Australian residents who have ceased (44.40%) or currently participate in musical activity (55.60%). Responses to an online questionnaire indicated that current participation in music was associated positively with a preference for reflective and complex music and the WHO‐Bref’s psychological quality of life dimension; and that current participation in music was associated negatively with peer musical engagement when growing up. Moreover, gender, age, and measures of musical background and experience were not significantly associated with continuing to participate in musical activities. These findings have clear implications for educators’ attempts foster continued musical participation
An illustrative analysis of technological alternatives for satellite communications
Get PDFThe demand for satellite communications services in the domestic market is discussed. Two approaches to increasing system capacity are the expansion of service into frequencies presently allocated but not used for satellite communications, and the development of technologies that provide a greater level of service within the currently used frequency bands. The development of economic models and analytic techniques for evaluating capacity expansion alternatives such as these are presented. The satellite orbit spectrum problem, and also outlines of some suitable analytic approaches are examined. Illustrative analysis of domestic communications satellite technology options for providing increased levels of service are also examined. The analysis illustrates the use of probabilities and decision trees in analyzing alternatives, and provides insight into the important aspects of the orbit spectrum problem that would warrant inclusion in a larger scale analysis
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