Discerning the Form of the Dense Core Mass Function

We investigate the ability to discern between lognormal and powerlaw forms for the observed mass function of dense cores in star forming regions. After testing our fitting, goodness-of-fit, and model selection procedures on simulated data, we apply our analysis to 14 datasets from the literature. Whether the core mass function has a powerlaw tail or whether it follows a pure lognormal form cannot be distinguished from current data. From our simulations it is estimated that datasets from uniform surveys containing more than approximately 500 cores with a completeness limit below the peak of the mass distribution are needed to definitively discern between these two functional forms. We also conclude that the width of the core mass function may be more reliably estimated than the powerlaw index of the high mass tail and that the width may also be a more useful parameter in comparing with the stellar initial mass function to deduce the statistical evolution of dense cores into stars.Comment: 6 pages, 2 figures, accepted for publication in PAS

Motion processing deficits in migraine are related to contrast sensitivity

Background: There are conflicting reports concerning the ability of people with migraine to detect and discriminate visual motion. Previous studies used different displays and none adequately assessed other parameters that could affect performance, such as those that could indicate precortical dysfunction. Methods: Motion-direction detection, discrimination and relative motion thresholds were compared from participants with and without migraine. Potentially relevant visual covariates were included (contrast sensitivity; acuity; stereopsis; visual discomfort, stress, triggers; dyslexia). Results: For each task, migraine participants were less accurate than a control group and had impaired contrast sensitivity, greater visual discomfort, visual stress and visual triggers. Only contrast sensitivity correlated with performance on each motion task; it also mediated performance. Conclusions: Impaired performance on certain motion tasks can be attributed to impaired contrast sensitivity early in the visual system rather than a deficit in cortical motion processing per se. There were, however, additional differences for global and relative motion thresholds embedded in noise, suggesting changes in extrastriate cortex in migraine. Tasks to study the effects of noise on performance at different levels of the visual system and across modalities are recommended. A battery of standard visual tests should be included in any future work on the visual system and migraine

Market orientation and service quality of public sector sport and recreation providers: a case study approach.

This study examines market orientation and service quality constructs within the public sector sport and recreation providers in the U.K. A preliminary review of the literature regarding marketing as a concept, its implementation and the constructs of service quality concludes that two models measure the constructs of market orientation and service quality adequately. These are the Kohli and Jaworski (1990) market orientation model and the Cronin and Taylor (1992; 1994) service quality measure. The market orientation model has been effectively linked to performance in other studies. Related studies concerning marketing in this sector have either concentrated upon generic issues, or attempts to measure service quality, but not the implementation of the marketing concept i.e. market orientation, simultaneously combined with the measurement of service quality. This research thus attempts to ful a void in knowledge by examining the market orientation and service quality constructs, and the link to organisational performance measured directly by income, expenditure and attendance for this service sector. This is in order to make a contribution to the more effective marketing and service quality management practice for this service industry. Employing a combined research design this study investigates the dimensional structures of the two constructs and the link to performance vía quantitative means. This approach also determines the existence of other related dimensions via the qualitative research methods adopted. Finally, evaluating the results against performance criteria to determine, where appropriate statistical significance. The nature of this service provisión enabled staff to be used for the quantitative study to measure the market orientation and service quality constructs to gain a surrogate "customer perspective". The two construct models proved to be reasonably robust, with many of the elements being retaíned in both after the iterative removal of elements via Cronbach alpha reliability tests. After principal component analysis, the dimensional constructs of both models were confirmed with the retained elements, although some dimensions subdivided due to questionnaire content (negatively worded items) and contextually specific items discovered in the service quality constructs (staff and physical facilities being considered as tangibles, but in two dimensional constructs). Múltiple analysis of variance identifíed some significant differences between the four cases, identifying a statistically significant link with performance for market orientation and service quality against the more extreme measurements of income, and attendance. This was only for two of the dimensional constructs of "Reliability" and "Tangibles" for the service quality dimensions however but still providing a useful method to determine a "non management" perspective for these two elements. The qualitative phase identifíed the possibility of other important dimensions whích included elements of the Narver and Slater (1990) market orientation dimensional construct, "competitor orientation" and "interfunctional coordination", and a further dimensión of "resources", which is probably unique to this service sector. lt was concluded that use could be made of the statistically significant elements that were found from this study of the dimensions of market orientation and service quality as a single measurement instrument. They could provide an indicative means of identifying important measures linked to functional issues underlying the marketing processes i.e. intelligence gathering, intelligence dissemination and responsiveness, as well as effective perceptual measurements of the "reliability" and "tangibles" which make up this service provisión

Community participation in the establishment and management of marine protected areas: A review of selected international experience

Conflicts between conservationists and people seeking access to land and natural resources have caused widespread criticism of conservation organizations and their activities throughout the world. Over the pastdecade, however, there has been recognition that the resources within protected areas often form part of the economic, social and political system of rural societies in the vicinity of the protected area. This has led tothe emergence of approaches that aim to involve those that are directly affected in the process of establishing and managing such areas. Key aspects of participatory approaches are: (i) the type of relationship betweenthe conservation agency and the role-players concerned; and (ii) the type of benefits that accrue to local people. A typology of participatory approaches is outlined and, through a literature review, case studies are drawn from a number of countries that have consulted users and adjacent communities on the establishment or management of protected areas

Survey of the administration of high school athletics in Massachusetts

Thesis (M.A.)--Boston University, 1948. This item was digitized by the Internet Archive

Forecasting Compositional Time Series with Exponential Smoothing Methods

Compositional time series are formed from measurements of proportions that sum to one in each period of time. We might be interested in forecasting the proportion of home loans that have adjustable rates, the proportion of nonagricultural jobs in manufacturing, the proportion of a rock's geochemical composition that is a specific oxide, or the proportion of an election betting market choosing a particular candidate. A problem may involve many related time series of proportions. There could be several categories of nonagricultural jobs or several oxides in the geochemical composition of a rock that are of interest. In this paper we provide a statistical framework for forecasting these special kinds of time series. We build on the innovations state space framework underpinning the widely used methods of exponential smoothing. We couple this with a generalized logistic transformation to convert the measurements from the unit interval to the entire real line. The approach is illustrated with two applications: the proportion of new home loans in the U.S. that have adjustable rates; and four probabilities for specified candidates winning the 2008 democratic presidential nomination.compositional time series, innovations state space models, exponential smoothing, forecasting proportions

Vortex Erosion in a Shallow Water Model of the Polar Vortex

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The erosion of a model stratospheric polar vortex in response to bottom boundary forcing is investigated numerically. Stripping of filaments of air from the polar vortex has been implicated in the occurrence of stratospheric sudden warmings (SSWs) but it is not understood in detail what factors determine the rate and amount of stripping. Here a shallow water vortex forced by topography is used to investigate the factors initiating stripping and whether this leads the vortex to undergo an SSW. It is found that the amplitude of topographic forcing must exceed some threshold (of order 200–450 m) in order for significant stripping to occur. For larger forcing amplitudes significant stripping occurs, but not as an instantaneous response to the forcing; rather, the forcing appears to initiate a process that ultimately results in stripping several tens of days later. There appears to be no simple quantitative relationship between the amount of mass stripped and the topography amplitude. However, at least over the early stages of the experiments, there is a good correlation between the amount of mass stripped and the global integral of wave activity, which may be interpreted as a measure of the accumulated topographic forcing. Finally there does not appear to be a simple correspondence between amount of mass stripped and the occurrence of an SSW.Robin Beaumont was supported during this research with a PhD studentship funded by an EPSRC Doctoral Training Grant

Lonely heart columns: A novel and entertaining way of teaching students abstract writing skills

Abstract writing is a key skill for science graduates; they are a common feature in many of the standard forms of scientific dissemination such as scientific research articles. In this paper we present a novel and entertaining approach for teaching abstract writing using adverts from lonely heart columns (LHC). Student constructed full profiles of the authors of LHC and constructed LHC profiles of celebrities to illustrate the key sills in abstract construction. There was no significant difference between the grades achieved by student taught using LHC and a more traditional approach, suggesting there were no negative impacts from this delivery method. Student in LHC tutorial overwhelmingly enjoy the tutorial, 95% responded the question ‘how would you rate the enjoyment of this tutorial’ as ‘much’ or ‘very much’. In addition to abstract writing two thirds of students in LHC tutorial believed they improved their ability to speak in front of others and their creative thinking skills. The LHC tutorial is a novel approach to teaching and learning that is both enjoyable and effective

A survey of parallel algorithms for fractal image compression

This paper presents a short survey of the key research work that has been undertaken in the application of parallel algorithms for Fractal image compression. The interest in fractal image compression techniques stems from their ability to achieve high compression ratios whilst maintaining a very high quality in the reconstructed image. The main drawback of this compression method is the very high computational cost that is associated with the encoding phase. Consequently, there has been significant interest in exploiting parallel computing architectures in order to speed up this phase, whilst still maintaining the advantageous features of the approach. This paper presents a brief introduction to fractal image compression, including the iterated function system theory upon which it is based, and then reviews the different techniques that have been, and can be, applied in order to parallelize the compression algorithm