827 research outputs found
Heavy Sneutrinos as Dark Matter
We calculate the relic density of very heavy, stable scalar neutrinos in the
minimal supersymmetric standard model. We include all two-body final states, as
well as the effects of co-annihilation with scalar electrons. We find that the
sneutrino relic density is in the cosmologically interesting region
0.1\ltwid\Omega_{\sn}h^2\ltwid 1.0 for 550\gev\ltwid\msn\ltwid 2300\gev.
For nominal values of the parameters of our galactic halo, recent results from
the Heidelberg--Moscow direct detection experiment set an upper limit on
\Omega_{\sn} which is lower by a factor ranging from two to ten, depending on
\msn.Comment: 7 pages in LaTeX, plus 1 uuencoded figure (uses epsf),
UCSBTH--94--29, UMN--TH--1306/9
What is success? Reflections on assisting BTEC students’ transitions into higher education
Presently, one in four students entering higher education (HE) hold a Business and Technology Education Council (BTEC) qualification. These vocational qualifications have played an important role in developing an additional educational pathway into universities for students often associated with under-represented groups and low participation regions, while widening participation initiatives have contributed to the increased number of BTEC students entering HE institutions (HEIs). Following on, potential approaches to support BTEC students during their first year at university were devised. One intervention has involved the development of an online module aimed to assist BTEC students’ transition from college to higher education. This article reflects upon the development of an online module implemented at a ‘selective’ university and examines what we actually define as 'success' within this context. The case study draws upon a variety of sources and provides not just an understanding of the project outcomes, but also an in-depth understanding about the more complex issues surrounding working with students to produce a successful project. Recommendations are provided for further work within this important field
Where did the votes go? Reassessing American party realignments via vote transfers between major parties from 1860 to 2008
Political scientists have long debated theories of electoral party realignments. In this paper, we apply ecological inference methods to statistically analyze the transfer of votes within counties in US presidential elections since 1860. Through this analysis we are able to identify the major periods of party realignment in US history and the counties where these shifts took place. As a result, we are able to provide new insights into American electoral history, and provide strong evidence that the 2008 presidential election did not represent a realigning election as the phrase is generally understood
Maternal Influenza Immunization and Reduced Likelihood of Prematurity and Small for Gestational Age Births: A Retrospective Cohort Study
In an analysis of surveillance data from the state of Georgia (US), Saad Omer and colleagues show an association between receipt of influenza vaccination among pregnant women and reduced risk of premature births
The "ram effect": new insights into neural modulation of the gonadotropic axis by male odors and socio-sexual interactions
Reproduction in mammals is controlled by the hypothalamo-pituitary-gonadal (HPG) axis under the influence of external and internal factors such as photoperiod, stress, nutrition, and social interactions. Sheep are seasonal breeders and stop mating when day length is increasing (anestrus). However, interactions with a sexually active ram during this period can override the steroid negative feedback responsible for the anoestrus state, stimulate LH secretion and eventually reinstate cyclicity. This is known as the ram effect and research into the mechanisms underlying it is shedding new light on HPG axis regulation. The first step in the ram effect is increased LH pulsatile secretion in anestrus ewes exposed to a sexually active male or only to its fleece, the latter finding indicating a pheromone-like effect. Estradiol secretion increases in all ewes and this eventually induces a LH surge and ovulation, just as during the breeding season. An exception is a minority of ewes that exhibit a precocious LH surge (within 4h) with no prior increase in estradiol. The main olfactory system and the cortical nucleus of the amygdala are critical brain structures in mediating the ram effect since it is blocked by their inactivation. Sexual experience is also important since activation (increased c-fos expression) in these and other regions is greatly reduced in sexually naïve ewes. In adult ewes kisspeptin neurons in both arcuate and preoptic regions and some preoptic GnRH neurons are activated 2h after exposure to a ram. Exposure to rams also activates noradrenergic neurons in the locus coeruleus and A1 nucleus and increased noradrenalin release occurs in the posterior preoptic area. Pharmacological modulation of this system modifies LH secretion in response to the male or his odor. Together these results show that the ram effect can be a fruitful model to promote both a better understanding of the neural and hormonal regulation of the HPG axis in general and also the spe
A cross-cultural study of music in history
Music lives in every culture, yet most investigations into music are based on Western music and Western listeners. This has not only ignored the cultural richness in music itself, but has also limited the impact of research on large varieties of societies. In reality, music is multi-cultural, multi-lingual and multi-facet. Evident in communication, education and healthcare systems, multi-cultural challenges have also merged into many aspects of our historical and contemporary societies. Moreover, rapid changes of the society and fast evolutionary development of media and technology have enriched world wealth of music. In this paper, we demonstrate that music has a rich but cross-cultural foundation in history with significance in linguistics, health and art. Consequently, we present a multi-disciplinary or multi-cultural study of music in history, revealing its significance in linguistics, health and wellbeing
Mechanism of age-dependent susceptibility and novel treatment strategy in glutaric acidemia type I
Glutaric acidemia type I (GA-I) is an inherited disorder of lysine and tryptophan metabolism presenting with striatal lesions anatomically and symptomatically similar to Huntington disease. Affected children commonly suffer acute brain injury in the context of a catabolic state associated with nonspecific illness. The mechanisms underlying injury and age-dependent susceptibility have been unknown, and lack of a diagnostic marker heralding brain injury has impeded intervention efforts. Using a mouse model of GA-I, we show that pathologic events began in the neuronal compartment while enhanced lysine accumulation in the immature brain allowed increased glutaric acid production resulting in age-dependent injury. Glutamate and GABA depletion correlated with brain glutaric acid accumulation and could be monitored in vivo by proton nuclear magnetic resonance (1H NMR) spectroscopy as a diagnostic marker. Blocking brain lysine uptake reduced glutaric acid levels and brain injury. These findings provide what we believe are new monitoring and treatment strategies that may translate for use in human GA-I
Hyperlexia in a 4-year-old boy with Autistic Spectrum Disorder
This paper presents a case study of a 4-year-old boy with Autistic Spectrum Disorder and a mental
age of approximately 1:5 who demonstrates precocious oral-reading behaviour in the absence of
spontaneous speech. Tests of reading regular and irregular words, pseudowords, homographic
heterophones, single sentences and texts were carried out. Performance on a variety of reading tasks
suggests the ability to use grapheme–phoneme correspondences and whole word reading for
decoding single words. In addition, successful reading of some homographic heterophones and
semantic paraphrasing of texts suggests a level of lexical, syntactic, semantic and pragmatic
development far beyond his mental or chronological age. The realisation of highly developed reading
ability is paradoxical in the context of profound impairment in cognitive development and an
absence of spoken language
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