3,627 research outputs found
Sterile neutrino dark matter, CDMS-II and a light Higgs boson
We add a singlet right handed neutrino plus a charged and a neutral singlet
scalars to the standard model. This extension includes a discrete symmetry such
that we obtain a heavy sterile neutrino which couples only to the electron and
the new scalars. In this sense the singlet neutrino does not mix with ordinary
ones and thus has no effect on Big Bang Nucleosynthesis. However, such sterile
neutrino can be in equilibrium with electroweak particles in the early Universe
due to its couplings to electrons and also because the Higgs boson mixes with
the singlet scalars. We obtain that the sterile neutrino constitutes a dark
matter candidate and analyze its direct detection in the light of current
experiments. Our results show that if such a sterile neutrino is realized in
nature, and CDMS-II experiment confirms its positive signal, dark matter
demands a rather light Higgs boson with new Physics at some 500 GeV scale.Comment: 16 pages, 13 figures, uses axodraw.st
Pond bottom dryout, liming. Part I. Disinfection in semi-intensive shrimp ponds.
Abstract: The main pond bottom soil management practices used in semi-intensive culture are pond dryout and liming between crops. These practices accelerate organic matter decomposition, neutralize soil acidity and destroy unwanted organisms. Since most soils become too dry for microbial decomposition of organic matter within three weeks, there is little need to dry pond bottoms more than that period. Where bottom sediment is deep, remove it to facilitate dryout. Ponds with soil pHs below 7.5 should be limed to enhance decomposition
Completeness of birth registration in Brazil: an overview of methods and data sources
We provide an analysis of the main sources of data used to estimate fertility schedules in
developing countries, giving special attention to Brazil. In addition to the brief history of
various data sources, we present several indirect demographic methods, commonly used
to estimate fertility and assess the quality of data. From the methods used, the Synthetic
Relational Gompertz model gives the most robust estimates of fertility, independent of
the data source considered. We conclude that different demographic data sources and
methods generate differing estimates of fertility and that the country should invest in
quality of birth statistics
Managing sport fish ponds to lessen nutrient discharge to streams.
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Antigenic expression in human choroid plexus carcinoma : report of two cases
Neoplasias provenientes do epitélio de revestimento do plexo coróide são inco-muns, tendo sido descritos 6 padrões morfológicos. O padrão anaplásico, também denominado carcinoma do plexo coróide, é o de menor freqüência e pode dar metastases fora do SNC. A distinção histológica desses tumores, particularmente da variedade anaplásica, com outras neoplasias primárias e metastáticas no SNC pode ser difícil. O uso de técnicas imunocitoquimicas em parafina tem-se mostrado útil no esclarecimento das linhagens tumorais. Os papilomas do plexo coróide têm, no entanto, sido objeto de controvérsia, por sua complexa expressão antigênica. Usando a técnica de imunoperoxidase (sistema avidina-biotina-peroxidase) pesquisaram-se, em dois casos da variedade anaplásica, os seguintes marcadores: proteína glial fibrilar ácida (GFAP) com anticorpo monoclonal e policlonal; ceratinas de 40-50kDa, ceratinas de 60-70kDa (callus ceratina), enolase neuronal específica (NSE) e proteína S-100, com anticorpos monoclonais. Os dois tumores mostraram positividade para NSE, proteína S-100 e ceratina de 40-50kDa; uma das duas neoplasias mostrou diferenciação glial, revelando positividade para GFAP tanto com anticorpo monoclonal quanto policlonal.Primary neoplasms of choroid plexus are rare. Six morphological variants have been described: papillary, cystic, acinar, mucus-secreting, oncocytic, and anaplastic. The anaplastic variant, the so-called choroid plexus carcinoma, is the rarest of all and can metastasize. The differential diagnosis of the anaplastic variant of choroid plexus neoplasms with adenocarcinomas, melanomas and indifferentiated neoplasms can be troublesome chiefly in adults. The now large use of immunocytochemical techniques in tissue section has become a powerful tool in the analysis of cell lineages, tumoral and non-tumoral. Nevertheless, the choroid plexus neoplasms have shown a complex and a somewhat confusing pattern of antigenic expression. In two choroid plexus carcinomas (one localized in the right lateral ventricle from a boy of 1 year and 9 months old, and the other localized in the left lateral ventricle from a girl of 3 years old) the following antigens were searched (using the avidin-biotin-peroxydase complex): glial fibrillary acidic protein (GFAP) with monoclonal and polyclonal antibodies; cytokeratins of 40-50kDa, cytokeratins of 60-70kDA (callus cytokeratin), neuronal specific enolase (NSE) and S-100 protein with monoclonal antibodies. The two neoplasms showed immunoreactivity against NSE, S-100 protein and cytokeratin of 40-50kDA The neoplasm of the boy exhibited glial differentiation having immunoreactivity against GFAP with monoclonal and polyclonal antibodies
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