9,206 research outputs found
Synaptonemal complex analysis of the sex bivalent in goats
Synaptonemal complex (SC) analysis of XY pairing in the goat (Capra hircus; 2n = 60) was investigated by electron microscopy for the first time in this species. Synapsis of the X and Y chromosomes begins during the mid-late zygotene stage as the autosomes complete their pairing. Only a small portion of the total length of the Y is paired with the X chromosome at this time. By the early pachytene, almost 90% of the Y is paired with the X. All the observed stages of the sex bivalent pairing showed the structural difference between the differential and pairing regions. In the pairing region, a synaptonemal complex is formed, while in the differential region the chromosome axes remain free
Synaptonemal complex analysis in goats carrying the 5/15 Robertsonian translocation
Synaptonemal complexes were analysed by electron microscopy in 2 bucks heterozygous for the 5/15 Robertsonian translocation. The cis configuration (free homologous 5 and 15 chromosomes on the same side of the 5/15 translocated chromosome) was found in all 50 cells examined. This feature is considered a prerequisite for the development of balanced gametes. No association between the sex bivalent and trivalent was observed
Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem
Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists
Pareto's Law of Income Distribution: Evidence for Germany, the United Kingdom, and the United States
We analyze three sets of income data: the US Panel Study of Income Dynamics
PSID), the British Household Panel Survey (BHPS), and the German Socio-Economic
Panel (GSOEP). It is shown that the empirical income distribution is consistent
with a two-parameter lognormal function for the low-middle income group
(97%-99% of the population), and with a Pareto or power law function for the
high income group (1%-3% of the population). This mixture of two qualitatively
different analytical distributions seems stable over the years covered by our
data sets, although their parameters significantly change in time. It is also
found that the probability density of income growth rates almost has the form
of an exponential function.Comment: Latex2e v1.6; 16 pages with 5 figure
Glassy magnetic phase driven by short range charge and magnetic ordering in nanocrystalline LaSrFeO: Magnetization, Mossbauer, and polarised neutron studies
The charge ordered LaSrFeO (LSFO) in bulk and
nanocrystalline forms are investigated using ac and dc magnetization,
M\"{o}ssbauer, and polarised neutron studies. A complex scenario of short range
charge and magnetic ordering is realized from the polarised neutron studies in
nanocrystalline specimen. This short range ordering does not involve any change
in spin state and modification in the charge disproportion between Fe
and Fe compared to bulk counterpart as evident in the M\"{o}ssbauer
results. The refinement of magnetic diffraction peaks provides magnetic moments
of Fe and Fe are about 3.15 and 1.57 for bulk, and
2.7 and 0.53 for nanocrystalline specimen, respectively. The
destabilization of charge ordering leads to magnetic phase separation, giving
rise to the robust exchange bias (EB) effect. Strikingly, EB field at 5 K
attains a value as high as 4.4 kOe for average size 70 nm, which is zero
for the bulk counterpart. A strong frequency dependence of ac susceptibility
reveals cluster-glass like transition around 65 K, below which EB
appears. Overall results propose that finite size effect directs the complex
glassy magnetic behavior driven by unconventional short range charge and
magnetic ordering, and magnetic phase separation appears in nanocrystalline
LSFO.Comment: 10 pages, 9 figures. Fig. 1 available upon request or in
http://www.ffn.ub.es/oscar/Articles.html. Accepted in Phys. Rev.
Airborne Geophysical And Tectonics Of The Ceará Central Domain, Eastern Region Of The Santa Quitéria Magmatic Arc, Borborema Province, Ne Brazil
The airborne geophysical data gamma-spectrometric and magnetic from Itatira Project (1977) was carried out, in the central region of the State of the Ceará, Brazil. Their processing produced products useful to indirectly identity regional geologic features. The verification and applicability of this approach was tested in a pilot-area whose limits are within the Umirim and Canindé topographic sheets, at 1:100,000 scale. The integration between the airborne geophysical and the geologic field data supported to the geologic mapping at the same cited scale. Two main units were recognized: the Santa Quitéria magmatic arc and the supracrustal sequences that surround the arc. The rocks from Santa Quitéria magmatic arc are characterized by high counting on the K-channel in its almost entire region and intermediate and low counting of eTh and eU. Generally, the supracrustal sequences are characterized by high values on the eU-and-eTh-channels and low on K-channel. The subunit metaultramafics and, mafics granulites, are remarkable by the occurrence retrograde eclogites bands and mafic granulites as lenses within gneisses and migmatites. These subunits present strong negative anomalies, with low counting on the three K, eTh and eU channels. That area also has positive magnetic anomalies, and may reflect high values of magnetic susceptibility.264527542ALMEIDA FFM, HASUIY, BRITO NEVES BB & FUCK RA. 1981. Brazilian structural provinces: An Introduction. Earth-Science Reviews, 17:1-29AMARAL WS. 2007. Integração de Dados Aerogeofísicos e Geológicos e sua Contribuição a Evolução Geodinâmica do Domínio Ceará Central, Província Borborema. Instituto de Geociências, Universidade Estadual de Campinas (UNICAMP), Dissertação de Mestrado, 165 pATTOH, K., High-pressure granulite facies metamorphism In the Pan-African Dahomeyide orogen, West Africa (1998) Journal of Geology, 106, pp. 236-246ARTHAUD MH. 2007. Evolução neoproterozóica do Grupo Ceará (Domínio Ceará Central, NE Brasil): da sedimentação à colisão continen- tal brasiliana. Instituto de Geociências, Universidade de Brasilia, Brasilia, Tese de Doutoramento. 132 pARTHAUD MH, CABY R, FUCK RA, DANTAS EL & PARENTE CV. 2008. Geology of the northern Borborema Province, NE Brazil and its correla- tion with Nigeria, NW Africa. In: PANKHURST RJ, TROUW RAJ, BRITO NEVES BB & DEWIT MJ (Org.). West Gondwana: Pre-Cenozoic Corre- lations Across the South Atlantic Region. London, Geological Society of London, Special Publications, 294: 49-67BLUM, M.L.B., JOST, H., MORAES, R.A.V., PIRES, A.C.B., Caracteriza- ção dos complexos ortognáissicos arqueanos de Goiás por gamaespec- trometria aérea. (2003) Revista Brasileira de Geociências, 33 (2). , suplemento 147-152BRITO NEVES, B.B., CORDANI, U.G., Tectonic evolution of South America during the Late Proterozoic (1991) Crustal Evolution In the Late Proterozoic, 53, pp. 23-40. , STERN RJ & VAN SCHMUS WR Ed, Precambrian ResearchBRITO NEVES, B.B., PASSARELLI, C.R., BASEI, M.A.S., SANTOS, E.J., U-Pb Zircon ages of some classic granites of the Borborema Province (2003) IV South American Symposium on Isotope Geology, , Salvador, Brazil, Short Papers, 158-159CABY, R., Precambrian terranes of Benin-Nigeria and northeast Brazil and the Late Proterozoic south Atlantic fit (1989) Geological Society of America Special Paper, 230, pp. 145-158CABY, R., Terrane assembly and geodynamic evolution of central- western Hoggar: A synthesis (2003) Journal of African Earth Sciences, 37, pp. 133-159CABY, R., ARTHAUD, M.H., Major Precambrian nappes of the Brazilian Belt, Ceará, Northeast Brazil (1986) Geology, 14, pp. 871-874CASTRO, N.A., (2004) Evolução Geológica Proterozóica da Região en- tre Madalena e Taperuaba, Domínio Tectônico Ceará Central (Província Borborema), , Instituto de Geociências, Universidade de São Paulo, Tese de Doutoramento, 221 pCAVALCANTE, J.C., VASCONCELOS, A.M., MEDEIROS, M.F., PAIVA, I.P., GOMES, F.E.M., CAVALCANTE, S.N., CAVALCANTE, J.E., BENEVIDES, H.C., (2003) Mapa Geológico do Estado do Ceará, , Escala 1:500.000. Fortaleza, Ministério das Minas e Energia/Companhia de Pesquisa de Recursos Minerais. CD-ROMCPRM (Serviço Geológico do Brasil). 1977. Levantamento Aerogeo- físico. Série 2000, Projeto Itatira. CPRM- NUCLEBRÁSDEBEGLIA, N., CORPEL, J., Automatic 3-D interpretation of poten- tial field data using analytic signal derivatives (1997) Geophysics, 62, pp. 87-96FERREIRA, V.P., SIAL, A.N., JARDIM, D.S.E., Geochemical and isotopic signatures of Proterozoic granitoids in terranes of the Borbo- rema structural province, northeastern Brazil (1995) Journal of South American Earth Science, 11 (5), pp. 419-455FETTER, A.H., (1999) U-Pb and Sm-Nd geochronological constraints on the crustal framework and geologic history of Ceará State, NW Borbo- rema Province, NE Brazil: Implications for the assembly of Gondwana, , Ph.D. thesis, Department of Geology, Kansas University, Lawrence, KS- USA,164pFETTER, A.H., SANTOS, T.J.S., VAN SCHMUS, W.R., HACKSPACHER, P.C., BRITO NEVES, B.B., ARTHAUD, M.H., NOGUEIRA, J.A., WERNICK, E., Evidence for Neoproterozoic Continental Arc Magmatism in the Santa Quitéria Batholith of Ceará State, NW Borborema Province, NE Brazil: Implications for the Assembly of West Gondwana (2003) Gondwana Research, 6 (2), pp. 265-273GARCIA, M.G.M., ARTHAUD, M.H., Caracterização de trajetória P-T em nappes brasilianas: Região de Boa Viagem/Madalena - Ceará Cen- tral (NE Brasil) (2004) Revista de Geologia, 17, pp. 173-191. , Universidade Federal do CearáMENDONÇA, J.C.G.S., CAMPOS, M., BRAGA, A.P.G., SOUZA, E.M., FAVALI, J.C., LEAL, J.R.L.V., Jazida de Urânio de Itataia-CE (1984) Principais Depósitos Minerais do Brasil, 1, pp. 121-131. , DNPMMILLIGAN, P.R., GUNN, P.J., (1997) Enhancement and presentation of airborne geophysical data. AGSO Journal of Australian Geology & Geo- physics, 17 (2), pp. 63-75MINTY, B.R.S., Simple Micro-Levelling for Aeromagnetic Data (1991) Expl. Geophys, 22, pp. 591-592PARENTE CV, SILVA FILHO WF & ALMEIDA AR. 2004. Bacias do Estágio da Transição do Domínio Setentrional da Província Borborema. In: MANTESSO NETO V, BARTORELLI A, CARNEIRO CDR & BRITO NE- VES BB (Ed.). Geologia do Continente Sul-Americano: Evolução da obra de Fernando Flávio Marques de Almeida. Editora Beca, São Paulo, 525-536ROEST, W.R., VERHOEF, J., PILKINGTON, M., Magnetic interpreta- tion using the 3-D analytic signal (1992) Geophysics, 57 (1), pp. 116-125SANTOS, T.J.S., FETTER, A.H., NOGUEIRA, N.J., Compari- sons between the northwestern Borborema Province, NE Brazil, and the southwestern Pharusian Dahomey Belt, SW Central Africa (2008) West Gondwana: Pre-Cenozoic Correlations Across the South Atlantic Region, 294, pp. 101-119. , PANKHURST RJ, TROUW RAJ, BRITO NEVES BB & DE WIT MJ Ed, Geological Society, London, Special PublicationsSILVA, A.M., McCAFFERTY, A.E., PIRES, A.C.B., An Integrated Ex- ploration Approach to Map BIF-Hosted Gold Deposits In the Rio das Velhas Greenstone Belt, Quadrilátero Ferrífero, Brazil (2003) Revista Brasileira de Geociências, 33 (2). , Supl. 29-36SILVA, L.C., ARMSTRONG, R., PIMENTEL, M.M., SCANDOLARA, J., RAM-, G.G., WILDNER, W., ANGELIM, L.A.A., ROSA, A.L.Z., Reavaliação da evolução geológica em terrenos pré-cambrianos brasileiros com base em novos dados U-Pb SHRIMP, Parte III: Províncias Borborema, Man- tiqueira Meridional e Rio Negro-Juruena (2002) Revista Brasileira de Geo- ciências, 32, pp. 529-544TEIXEIRA MLA. 2005. Integração de Dados aerogeofí sicos, Geológicos e Isotópicos do Limite Norte do Complexo Tamboril-Santa Quitéria-CE, Província Borborema. Inst. de Geociências, Universidade de Brasilia, Brasilia, Dissertação de Mestrado, 86 pTROMPETTE, R., (1994) Geology of western Gondwana, Pan-African/Brasi- liano Aggregation of South America and Africa, , A.A. Balkema, Rotterdam, Brookfield, 350
Prevalence of Trichomonas Vaginalis in Women with Precancerous and Indeterminate Lesions at Cytology
Trichomonas vaginalis was investigated by cervicovaginal cytology in pregnant and non-pregnant women receiving care at two public referral hospitals in Goiacircnia, Goias, Brazil. The frequency of Trichomonas vaginalis infection, the correlation between its presence and a diagnosis of precancerous and indeterminate lesions, and potential inflammatory changes in the vaginal epithelial cells in the presence of the parasite were evaluated.Overall, 359 Papanicolaou smears from 157 pregnant women and 202 non-pregnant women were evaluated.nbsp The principal inflammatory changes associated with the presence of T. vaginalis were registered.A second examiner reevaluated the slides. T. vaginalis infection was found in 46% of the slides, withprecancerous lesionsbeing found in 4.2% of the infected women.nbsp Perinuclear halos were the most common inflammatory change associated with the presence of the parasite.nbsp Adherence of the parasite to the vaginal epithelial cellsand ill-defined cytoplasmic borders were more commonly found in the group of pregnant patients.nbsp The prevalence of T. vaginalis was high in the present study, both in the pregnant and non-pregnant women.nbsp The socioeconomic level of the study population and the examinersrsquo experience played a particularly relevant role in the results obtained
Ice Age Epochs and the Sun's Path Through the Galaxy
We present a calculation of the Sun's motion through the Milky Way Galaxy
over the last 500 million years. The integration is based upon estimates of the
Sun's current position and speed from measurements with Hipparcos and upon a
realistic model for the Galactic gravitational potential. We estimate the times
of the Sun's past spiral arm crossings for a range in assumed values of the
spiral pattern angular speed. We find that for a difference between the mean
solar and pattern speed of Omega_Sun - Omega_p = 11.9 +/- 0.7 km/s/kpc the Sun
has traversed four spiral arms at times that appear to correspond well with
long duration cold periods on Earth. This supports the idea that extended
exposure to the higher cosmic ray flux associated with spiral arms can lead to
increased cloud cover and long ice age epochs on Earth.Comment: 14 pages, 3 figures, accepted for publication in Ap
Levantamento de reconhecimento de baixa intensidade dos solos da Reserva Extrativista do Alto Juruá, Marechal Thaumaturgo, Acre.
Este trabalho foi executado pela Universidade Federal do Acre (Ufac) em cooperação com a Fundação de Tecnologia do Estado do Acre (Funtac), Embrapa Acre e Universidade Estadual de Campinas (Unicamp). O levantamento de solos, em nível de reconhecimento de baixa intensidade, compreende a Reserva Extrativista do Alio Juruá, localizada entre as coordenadas geográficas de 08 0 45' e 09 0 45' 8, de latitude sul e 72 0 00' e 730 00' W, longitude a oeste. A metodologia utilizada é a mesma que a Embrapa Solos vem utilizando em estudos similares. Realizaram-se análises físicas e químicas no Laboratório de Solos da Embrapa Acre e as análises de ataque sulfúrico no laboratório da Embrapa Solos. No desenvolvimento da prospecção pedológica foram utilizadas imagens TM 345/Landsat - 5, 1992, tratadas no Laboratório de Processamento de Informações Georreferenciadas da Unicamp, na escala de 1:100.000 e 1:200.000. Os mapas finais de solos foram elaborados na escala de 1:250.000, com unidades de mapeamento em associações, dada a limitação da escala. Os principais solos encontrados na área são: Alissolos, Luvissolos, Cambissolos, Chemossolos, Gleissolos e Neossolos. Exduindo a alta fertilidade, os solos da Reserva Extrativista do Alto Juruá apresentam sérias restrições de uso quando se consideram as condições de relevo em que estão inseridos. A área apresenta relevo ondulado a forte ondulado e solos com alto gradiente textural, implicando em alta susceptibilidade à erosão. Observou-se, em algumas áreas de relevo forte ondulado e sobre a ocorrência de Cambissolo e floresta tropical aberta, erosão laminar ligeira. No caso de retirada da floresta natural, este processo erosivo irá se intensificar, causando danos irreversíveis ao solo e, conseqüentemente, ao ambiente.bitstream/item/116590/1/6765.pd
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