11,984 research outputs found
Recommended from our members
The Role of the Brain in the Pathogenesis and Physiology of Polycystic Ovary Syndrome (PCOS).
Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder, affecting at least 10% of women of reproductive age. PCOS is typically characterized by the presence of at least two of the three cardinal features of hyperandrogenemia (high circulating androgen levels), oligo- or anovulation, and cystic ovaries. Hyperandrogenemia increases the severity of the condition and is driven by increased luteinizing hormone (LH) pulse secretion from the pituitary. Indeed, PCOS women display both elevated mean LH levels, as well as an elevated frequency of LH pulsatile secretion. The abnormally high LH pulse frequency, reflective of a hyperactive gonadotropin-releasing hormone (GnRH) neural circuit, suggests a neuroendocrine basis to either the etiology or phenotype of PCOS. Several studies in preclinical animal models of PCOS have demonstrated alterations in GnRH neurons and their upstream afferent neuronal circuits. Some rodent PCOS models have demonstrated an increase in GnRH neuron activity that correlates with an increase in stimulatory GABAergic innervation and postsynaptic currents onto GnRH neurons. Additional studies have identified robust increases in hypothalamic levels of kisspeptin, another potent stimulator of GnRH neurons. This review outlines the different brain and neuroendocrine changes in the reproductive axis observed in PCOS animal models, discusses how they might contribute to either the etiology or adult phenotype of PCOS, and considers parallel findings in PCOS women
Assessing the Prosody of Non-Native Speakers of English: Measures and Feature Sets
In this paper, we describe a new database with audio recordings of non-native (L2) speakers of English, and the perceptual evaluation experiment conducted with native English speakers for assessing the prosody of each recording. These annotations are then used to compute the gold standard using different methods, and a series of regression experiments is conducted to evaluate their impact on the performance of a regression model predicting the degree of Abstract naturalness of L2 speech. Further, we compare the relevance of different feature groups modelling prosody in general (without speech tempo), speech rate and pauses modelling speech tempo (fluency), voice quality, and a variety of spectral features. We also discuss the impact of various fusion strategies on performance.Overall, our results demonstrate that the prosody of non-native speakers of English as L2 can be reliably assessed using supra- segmental audio features; prosodic features seem to be the most important ones
Many-body system with a four-parameter family of point interactions in one dimension
We consider a four-parameter family of point interactions in one dimension.
This family is a generalization of the usual -function potential. We
examine a system consisting of many particles of equal masses that are
interacting pairwise through such a generalized point interaction. We follow
McGuire who obtained exact solutions for the system when the interaction is the
-function potential. We find exact bound states with the four-parameter
family. For the scattering problem, however, we have not been so successful.
This is because, as we point out, the condition of no diffraction that is
crucial in McGuire's method is not satisfied except when the four-parameter
family is essentially reduced to the -function potential.Comment: 8 pages, 4 figure
Dirac and Majorana heavy neutrinos at LEP II
The possibility of detecting single heavy Dirac and Majorana neutrinos at LEP
II is investigated for heavy neutrino masses in the range . We study the process as a clear signature for heavy neutrinos. Numerical estimates for
cross sections and distributions for the signal and the background are
calculated and a Monte Carlo reconstruction of final state particles after
hadronization is presented.Comment: 4 pages, 8 figure
Sistema de gestão territorial da faixa de fronteira para a defesa agropecuária.
Os problemas sanitários agropecuários desconhecem fronteiras, principalmente quando há continuidade terrestre, como é o caso de faixa fronteiriça entre e o Paraguai, a BolÃvia e o Peru. A Embrapa Monitoramento por Satélite e a Secretaria de Defesa Agropecuária do Ministério da Agricultura, Pecuária e Abastecimento desenvolveram um sistema de gestão territorial da faixa de fronteira para a defesa agropecuária com o objetivo principal de contribuir para a erradicação da febre aftosa. O sistema agrupa, organiza e disponibiliza informações espaciais detalhadas de toda faixa de fronteira internacional, compreendida entre os estados brasileiros do Acre, Rondônia, Mato Grosso e Mato Grosso do Sul e Peru, a BolÃvia e o Paraguai. Para seu desenvolvimento, foi utilizada um base iconográfica composta por imagens dos satélites Landsat, CBERS, Eros e Spot. É fato que, ora a aplicação de todas as ferramentas fornecidas pelo sistema, é necessário que os agentes envolvidos percebam sua potencialidade. O sistema sozinho não é capaz de fornecer soluções para a erradicação da febre aftosa, assim como para o controle de outras zoonoses
- …