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Alterações da substância branca cerebral relacionadas com o envelhecimento

Baptista, Miguel José de Carvalho Viana
Fonte: Faculdade de Ciências Médicas. Universidade Nova de Lisboa Publicador: Faculdade de Ciências Médicas. Universidade Nova de Lisboa
Tipo: Tese de Doutorado
Publicado em //2009 POR
Relevância na Pesquisa
25.98%
INTRODUÇÃO: Estudos prévios, com técnicas de imagem, documentam de forma consistente a existência de alterações da substância branca cerebral relacionadas com o envelhecimento (ASBRE). Tais alterações poderão ter um papel importante no declínio funcional do idoso, reflectindo‐se sobretudo no desempenho motor e cognitivo, com repercussão evidente na prática clínica. Apesar disso, a caracterização em definitivo dos fenótipos clínicos e da evolução das ASBRE continua por esclarecer, possivelmente pelas dificuldades metodológicas de que se reveste o seu estudo, incluindo: a adequação das baterias neuropsicológicas, a utilização de amostras de doentes com diferentes graus de severidade e de envolvimento regional, as limitações das diferentes escalas e a sensibilidade dos diferentes métodos de imagem. A Ressonância Magnética (RM) de difusão tem revelado grande sensibilidade para as alterações isquémicas, admitindo‐se que poderá permitir uma melhor caracterização das ASBRE e deste modo possibilitar uma correlação mais precisa com as variáveis cognitivas e motoras, permitindo avaliar ainda a substância branca aparentemente normal (SBAN). OBJECTIVOS: Descrever a evolução imagiológica das ASBRE no intervalo de um ano e analisar a sua expressão clínica e impacto funcional; identificar factores preditivos de progressão das ASBRE e de declínio funcional associado. Descrever a expressão clínica e perfil evolutivo dos doentes com ASBRE com envolvimento preferencial da região parieto‐occipital; comparar este grupo de doentes com os doentes com ASBRE...

Plasmablastic multiple myeloma is associated with increased vascular endothelial growth factor immunoexpression

Ribas,C.; Colleoni,G.W.B.; Almeida,M.S.S.; Aguiar,K.C.C.; Silva,M.R.R.; Bordin,J.O.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2005 EN
Relevância na Pesquisa
55.67%
The biologic basis of the negative prognosis of plasmablastic myeloma is not fully understood. To determine whether histologically aggressive multiple myeloma (MM) is associated with a more angiogenic marrow environment, bone marrow samples from 50 recently diagnosed MM patients were evaluated. Twelve percent (6/50) of patients presented plasmablastic MM, and this feature correlated with moderate/strong intensity of vascular endothelial growth factor staining of plasma cells (P = 0.036). Although plasmablastic MM was not associated with increasing of microvessel density, this new evidence of increased expression of vascular endothelial growth factor on plasmablasts suggests that the adverse prognosis conferred by plasmablastic disease may be due, at least in part, to secretion of this angiogenic cytokine, also suggesting that the subset of MM patients with plasmablastic features may derive particular benefit from antiangiogenic therapies.

Competitive Ability and Efficiency in Nodule Formation of Strains of Bradyrhizobium japonicum†

McDermoti, Timothy R.; Graham, Peter H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1990 EN
Relevância na Pesquisa
35.7%
In the American Midwest, superior N2-fixing inoculant strains of Bradyrhizobium japonicum consistently fail to produce the majority of nodules on the roots of field-grown soybean. Poor nodulation by inoculant strains is partly due to their inability to stay abreast of the expanding soybean root system in numbers sufficient for them to be competitive with indigenous bradyrhizobia. However, certain strains are noncompetitive even when numerical dominance is not a factor. In this study, we tested the hypothesis that the nodule occupancy achieved by strains is related to their nodule-forming efficiency. The nodulation characteristics and competitiveness of nine strains of B. japonicum were compared at both 20 and 30°C. The root tip marking technique was used, with the nodule-forming efficiency of each strain estimated from the average position of the uppermost nodule and the number of nodules formed above the root tip mark. The competitiveness of the nine strains relative to B. japonicum USDA 110 was determined by using immunofluorescence to identify nodule occupants. The strains differed significantly in competitiveness with USDA 110 and in nodulation characteristics, strains that were poor competitors usually proving to be inferior in both the average position of the uppermost root nodule and the number of nodules formed above the root tip mark. Thus...

Differences between female and male patients with familial rheumatoid arthritis

Laivoranta-Nyman, S; Luukkainen, R; Hakala, M; Hannonen, P; Mottonen, T; Yli-Kerttula, U; Ilonen, J; Toivanen, A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2001 EN
Relevância na Pesquisa
35.61%
OBJECTIVE—To determine whether there are genetic differences between female and male patients with familial rheumatoid arthritis (RA).
METHODS—45 men and 119 women from 78 families with RA who all had at least one first degree relative with RA were compared. HLA-DRB1 alleles were analysed, including DRB1*04 subtypes and associations of DRB1*04 haplotypes with DQB1*0301 or DQB1*0302 alleles, the age of the patients at disease onset, the presence of rheumatoid factor (RF), joint erosions, and rheumatoid nodules.
RESULTS—HLA-DRB1*13 allele (the subtype allele of DR6, reported to be protective against the development of RA) was found in 14/119 (12%) of female but in none of the male patients (p=0.036). The HLA-DR4 allele was found slightly more often in men than women patients with familial RA (31/45 (69%) v 75/119 (63%), NS). Men were also more often RF positive than women (44/45 (98%) v 98/117 (84%); p=0.031). On the other hand, the mean age at onset of RA was significantly lower in the female group (40.4 years) than in men (46.6 years, p=0.0044).
CONCLUSION—The results indicate that there is stronger genetic background in familial male than female patients with RA in the genetic susceptibility defined by the studied HLA antigens. However...

Nuclear BAG-1 expression reflects malignant potential in colorectal carcinomas

Kikuchi, R; Noguchi, T; Takeno, S; Funada, Y; Moriyama, H; Uchida, Y
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.61%
BAG-1 is a recently identified Bcl-2-interacting anti-apoptotic protein. The aim of our study was to investigate the immunohistochemical staining pattern of BAG-1 protein in patients with colorectal cancer and examine associations of BAG-1 expression with various clinicopathological factors and patient survival. Tumour samples were collected from 86 patients diagnosed with colorectal cancer. There was significant variation in the immunohistochemical staining patterns for BAG-1, including absent staining and staining of either the cytoplasm, nucleus or both. Twenty-one colorectal carcinomas (24.4%) exhibited a nuclear staining pattern whilst 56 (65.1%) exhibited cytoplasmic staining. The percentage of cases exhibiting nuclear BAG-1 positivity was significantly higher in distant metastasis-positive cases (55.6%) than in distant metastasis-negative cases (20.8%; P=0.036). Overall survival was significantly shorter for patients with tumours exhibiting BAG-1 positive nuclei than those with absent nuclear BAG-1-staining (P=0.011). In addition, the multivariate cox proportional hazard models indicated that nuclear BAG-1 expression was the only independent prognostic variable for mortality (P=0.013). These studies demonstrate that nuclear BAG-1 expression is a useful predictive factor for distant metastasis and a poor prognosis in patients with colorectal cancer.

Lymphoma cell VEGFR2 expression detected by immunohistochemistry predicts poor overall survival in diffuse large B cell lymphoma treated with immunochemotherapy (R-CHOP)

Gratzinger, Dita; Advani, Ranjana; Zhao, Shuchun; Talreja, Neha; Tibshirani, Robert J.; Shyam, Ragini; Horning, Sandra; Sehn, Laurie H.; Farinha, Pedro; Briones, Javier; Lossos, Izidore S.; Gascoyne, Randy D.; Natkunam, Yasodha
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.66%
Diffuse large B cell lymphoma (DLBCL) is clinically and biologically heterogeneous. In most cases of DLBCL, lymphoma cells coexpress vascular endothelial growth factor (VEGF) and its receptors VEGFR1 and VEGFR2, suggesting autocrine in addition to angiogenic effects. We enumerated microvessel density and scored lymphoma cell expression of VEGF, VEGFR1, VEGFR2 and phosphorylated VEGFR2 in 162 de novo DLBCL patients treated with R-CHOP (rituximab, cyclophosphamide, vincristine, doxorubicin and prednisone)-like regimens. VEGFR2 expression correlated with shorter overall survival (OS) independent of International Prognostic Index (IPI) (p=0.0028). Phosphorylated VEGFR2 (detected in 13% of cases) correlated with shorter progression-free survival (PFS, p=0.044) and trended toward shorter OS on univariate analysis. VEGFR1 was not predictive of survival on univariate analysis, but it did correlate with better OS on multivariate analysis with VEGF, VEGFR2, and IPI (p=0.036); in patients with weak VEGFR2, lack of VEGFR1 coexpression was significantly correlated with poor OS independent of IPI (p=0.01). These results are concordant with our prior finding of an association of VEGFR1 with longer OS in DLBCL treated with chemotherapy alone. We postulate that VEGFR1 may oppose autocrine VEGFR2 signaling in DLBCL by competing for VEGF binding. In contrast to our prior results with chemotherapy alone...

Influence of genetic variants in the apolipoprotein A5 and C3 gene on lipids, lipoproteins, and its association with coronary artery disease in Indians

Bhanushali, Aparna A.; Das, Bibhu R.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.7%
Indians worldwide demonstrate a triad of elevated triglyceride (TG) with high low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol levels. In the present study, we aim to investigate the effect of −1131T > C, −3A > G, c.56 C > G, and c.553 G > T SNPs in the apolipoprotein A5 (APOA5) gene and 1100C > T and 3238C > G in the apolipoprotein C3 (APOC3) on plasma lipid and lipoprotein levels and risk of coronary artery disease (CAD) in Indians. Genotyping and lipid assays were carried out using standard protocols in a study population that included 150 controls and 90 cases with CAD. Significant associations between minor alleles and higher TG levels were seen for −1131T > C (P < 0.001), −3A > G (P < 0.001), c.56C > G (P = 0.026), and c.553G > T (P = 0.003) SNPs in the APOA5 gene and 1100C > T (P = 0.001) and 3238C > G (P = 0.009) in the APOC3 gene. The haplotypes 11211, 22111, 11112, and 22112 were significantly associated with TG levels (P = 0.025, P = 0.017, P = 0.027, and P < 0.001, respectively) and very-low-density lipoprotein cholesterol levels (P = 0.025, P = 0.017, P < 0.001, and P = 0.002) in males. The 22111...

Current Practice of Heart Donor Evaluation in Germany: Multivariable Risk Factor Analysis Confirms Practicability of Guidelines

Zeissig, Sylke Ruth; Fischer-Froehlich, Carl-Ludwig; Polster, Frank; Fruehauf, Nils R.; Kirste, Guenter; Schmidtmann, Irene
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
45.65%
Background. Organ shortage has liberalised the acceptance criteria of grafts for heart transplantation, but which donor characteristics ultimately influence the decision to perform transplantation? For the first time this was evaluated using real-time donor data from the German organ procurement organization (DSO). Observed associations are discussed with regard to international recommendations and guidelines. Methods. 5291 German donors (2006–2010) were formally eligible for heart donation. In logistic regression models 160 donor parameters were evaluated to assess their influence on using grafts for transplantation (random split of cases: 2/3 study sample, 1/3 validation sample). Results. Successful procurement was determined by low donor age (OR 0.87 per year; 95% CI [0.85–0.89], P < 0.0001), large donor height (OR 1.04 per cm; 95% CI [1.02–1.06], P < 0.0001), exclusion of impaired left ventricular function or wall motion (OR 0.01; 95% CI [0.002–0.036], P < 0.0001), arrhythmia (OR 0.05; 95% CI [0.009–0.260], P = 0.0004), and of severe coronary artery disease (OR 0.003; 95% CI [<0.001–0.01], P < 0.0001). Donor characteristics differed between cases where the procedure was aborted without and with allocation initiated via Eurotransplant.

HLA-G Expression Is an Independent Predictor for Improved Survival in High Grade Ovarian Carcinomas

Rutten, M. J.; Dijk, F.; Savci-Heijink, C. D.; Buist, M. R.; Kenter, G. G.; van de Vijver, M. J.; Jordanova, E. S.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.63%
Aberrant expression of human leukocyte antigens (HLA) class I has prognostic importance in various cancers. Here, we evaluated the prognostic value of classical (A/B/C) and nonclassical (G/E) HLA expression in 169 high grade epithelial ovarian cancer samples and linked that to clinicopathological characteristics and survival. Expression of HLA-A, -B/C, or -E was not correlated with survival. Survival was prolonged when tumours expressed HLA-G (P = 0.008) and HLA-G was an independent predictor for better survival (P = 0.011). In addition, HLA-G expression was associated with longer progression-free survival (P = 0.036) and response to chemotherapy (P = 0.014). Accordingly, high expression of HLA-G mRNA was associated with prolonged disease-free survival (P = 0.037) in 65 corresponding samples. Elevated serum-soluble HLA-G levels as measured by enzyme-linked immunosorbent assay in 50 matched patients were not correlated to HLA-G protein expression or gene expression nor with survival. During treatment, sHLA-G levels declined (P = 0.038). In conclusion, expression of HLA-G is an independent prognostic factor for improved survival in high grade epithelial ovarian cancer and a predictor for platinum sensitivity.

A retrospective analysis of the effect of intraoperative opioid dose on cancer recurrence after non-small cell lung cancer resection

Cata, Juan P; Keerty, Visesh; Keerty, Dinesh; Feng, Lei; Norman, Peter H; Gottumukkala, Vijaya; Mehran, John R; Engle, Mitchel
Fonte: BlackWell Publishing Ltd Publicador: BlackWell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
35.64%
Preclinical studies have demonstrated that opioid receptor agonists increase the rate of non-small cell lung cancer (NSCLC) growth and metastasis. Following institutional review board approval, we retrieved data on 901 patients who underwent surgery for NSCLC at MD Anderson Cancer Center. Comprehensive demographics, intraoperative data, and recurrence-free survival (RFS) and overall survival (OS) at 3 and 5 years were obtained. Cox proportional analyses were conducted to assess the association between intraoperative opioid exposure and RFS and OS. The median intraoperative fentanyl equivalents dosage was 10.15 μg/kg. The multivariate analysis by stage indicated that a trend toward significance for opioid consumption as a risk factor in stage I patients (P = 0.053). No effect was found on RFS for stage II or III patients. Alternatively, opioid consumption was a risk factor for OS for stage I patients (P = 0.036), whereas no effect was noted for stage II or III patients. Intraoperative opioid use is associated with decreased OS in stage I but not stage II–III NSCLC patients. Until randomized controlled studies explore this association further, opioids should continue to be a key component of balanced anesthesia.

Perfil de saúde de mães e gestantes residentes na região semi-árida do estado de Alagoas.; Pregnant Anemia; Anthropometrics; Low birth weight; Maternal infantile health; Nutritional state

Moura, Fabiana Andrea
Fonte: Universidade Federal de Alagoas; BR; Nutrição; Programa de Pós-Graduação em Nutrição; UFAL Publicador: Universidade Federal de Alagoas; BR; Nutrição; Programa de Pós-Graduação em Nutrição; UFAL
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
35.77%
The mothers and pregnant health have narrows relationship with their children s health, and the socioeconomic condition interferes in an important way in the profile of those varied. Alagoas is the state more poor of Union and, in the internal context, its population of the semi-arid area still meets in conditions of social and economical vulnerability in level larger than the other population contingents of the State. Before that, it had aimed at to elaborate a diagnosis of the conditions of mothers and pregnant health resident in that area, identifying the main risk factors associated. Starting from a probabilistic sample were collected, demographic, socioeconomic, anthropometrics and health data of 1180 mothers, 1511 smaller children 10 years old and of 150 pregnant. The data had typed in double independent entrance using the program Epi-info 3.2.2 and statistically analyzed by SPSS version 13.0. The lineal regression analysis was accomplished with all the variables that presented correlation of Pearson lesser than 0.7. They were considered significant the associations that presented after regression lineal multiple analysis p<0.05. The first article called: Women of short stature present a greater prevalence of obesity and hypertension and undernourished sons: probabilistic study in the semi-arid region of Alagoas...

Measurement of soil carbon oxidation state and oxidative ratio by ¹³C nuclear magnetic resonance; Measurement of soil carbon oxidation state and oxidative ratio by (13)C nuclear magnetic resonance

Hockaday, W.; Masiello, C.; Randerson, J.; Smernik, R.; Baldock, J.; Chadwick, O.; Harden, J.
Fonte: Amer Geophysical Union Publicador: Amer Geophysical Union
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
35.67%
The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O₂and CO₂ fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO₂sink using atmospheric measurements of changing O₂ and CO₂levels. To estimate the OR of the terrestrial biosphere, measurements are needed of changes in the OR of aboveground and belowground carbon pools associated with decadal timescale disturbances (e.g., land use change and fire). The OR of aboveground pools can be measured using conventional approaches including elemental analysis. However, measuring the OR of soil carbon pools is technically challenging, and few soil OR data are available. In this paper we test three solid-state nuclear magnetic resonance (NMR) techniques for measuring soil OR, all based on measurements of the closely related parameter, organic carbon oxidation state (Cox). Two of the three techniques make use of a molecular mixing model which converts NMR spectra into concentrations of a standard suite of biological molecules of known Cox. The third technique assigns Cox values to each peak in the NMR spectrum. We assess error associated with each technique using pure chemical compounds and plant biomass standards whose Cox and OR values can be directly measured by elemental analyses. The most accurate technique...

The intestinal epithelial cell differentiation marker intestinal alkaline phosphatase (ALPi) is selectively induced by histone deacetylase inhibitors (HDACi) in colon cancer cells in a Kruppel-like Factor 5 (KLF5)-defendent manner

Shin, J.; Carr, A.; Corner, G.A.; Tögel, L.; Dávaos-Salas, M.; Tran, H.; Chueh, A.C.; Al-Obaidi, S.; Chionh, F.; Ahmed, N.; Buchanan, D.D.; Young, J.P.; Malo, M.S.; Hodin, R.A.; Arango, D.; Sieber, O.M.; Augenlicht, L.H.; Dhillon, A.S.; Weber, T.K.; Mar
Fonte: American Society for Biochemistry and Molecular Biology Publicador: American Society for Biochemistry and Molecular Biology
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
55.61%
The histone deacetylase inhibitor (HDACi) sodium butyrate promotes differentiation of colon cancer cells as evidenced by induced expression and enzyme activity of the differentiation marker intestinal alkaline phosphatase (ALPi). Screening of a panel of 33 colon cancer cell lines identified cell lines sensitive (42%) and resistant (58%) to butyrate induction of ALP activity. This differential sensitivity was similarly evident following treatment with the structurally distinct HDACi, MS-275. Resistant cell lines were significantly enriched for those harboring the CpG island methylator phenotype (p = 0.036, Chi square test), and resistant cell lines harbored methylation of the ALPi promoter, particularly of a CpG site within a critical KLF/Sp regulatory element required for butyrate induction of ALPi promoter activity. However, butyrate induction of an exogenous ALPi promoter-reporter paralleled up-regulation of endogenous ALPi expression across the cell lines, suggesting the presence or absence of a key transcriptional regulator is the major determinant of ALPi induction. Through microarray profiling of sensitive and resistant cell lines, we identified KLF5 to be both basally more highly expressed as well as preferentially induced by butyrate in sensitive cell lines. KLF5 overexpression induced ALPi promoter-reporter activity in resistant cell lines...

The autoreactivity of B cells in hereditary angioedema due to C1 inhibitor deficiency

Kessel, A; Peri, R; Perricone, R; Guarino, M D; Vadasz, Z; Novak, R; Haj, T; Kivity, S; Toubi, E
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Publicado em /03/2012 EN
Relevância na Pesquisa
35.69%
Patients with hereditary angioedema (HAE) tend to produce autoantibodies and have a propensity to develop immunoregulatory disorders. We characterize the profile of autoantibodies in a group of HAE patients and investigate their memory B cells' phenotype and activation status. We studied the activity status phenotype, Toll-like receptor (TLR)-9 expression and total phosphotyrosine in B cells isolated from HAE patients. Additionally, the following autoantibodies were assessed in the serum of 61 HAE patients: anti-nuclear, rheumatoid factor, anti-cardiolipin, anti-tissue transglutaminase, anti-endomysial, anti-Saccharomyces cerevisiae, anti-thyroid and anti-neutrophil cytoplasmic antibodies. In 47·5% of HAE patients we detected at least one of the tested autoantibodies. Expression of CD69, CD5 and CD21 was found to be significantly higher on memory B cells from HAE patients compared to healthy controls (4·59 ± 4·41 versus 2·06 ± 1·81, P = 0·04, 8·22 ± 7·17 versus 3·65 ± 3·78, P = 0·05, 2·43 ± 0·54 versus 1·92 ± 0·41, P = 0·01, respectively). Total phosphotyrosine in B cells from HAE patients was significantly higher compared to healthy controls (4·8 ± 1·1 versus 2·7 ± 1·3, P = 0·0003). Memory B cells isolated from the HAE group contained higher amounts of TLR-9 compared to healthy controls (8·17 ± 4·1 versus 4·56 ± 1·6...

Lung function prediction equations derived from healthy South African gold miners

Hnizdo, E.; Churchyard, G.; Dowdeswel, R.
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /10/2000 EN
Relevância na Pesquisa
35.68%
OBJECTIVES—To estimate lung function prediction equations and to identify appropriate normal reference values for the population of about 250 000 of South African gold miners.
METHODS—Data from a lung function screening programme conducted at a large South African gold mine from 1994 to 1998 were used to estimate the lung function prediction equations. The most reliable period of lung function testing was identified in a previous study of a temporal pattern in reliability, and lung function tests from this period were used. Miners with a history of pulmonary tuberculosis or with radiological abnormalities were excluded from the study. The prediction equations were estimated cross sectionally on 15 772 black and 2752 white miners, and published reference equations that fitted most closely the observed data were identified.
RESULTS—The estimated prediction equations for forced vital capacity (FVC) are as follows: for black men, FVC (l)=− 2.901−0.025×age+4.655×height; and for white men, FVC(l)=−4.407−0.036×age+ 5.940×height. For forced expiratory volume in one second (FEV1) these equations are: for black men, FEV1(l)=−1.654− 0.30×age+3.665×height; and for white men, FEV1(l)= −2.341− 0.038×age+4.314×height. Units are years for age and metres for height. Knudson's and the European Community of Coal and Steel (ECCS) reference values provided the closest fit to the data on lung function of white miners...

N' -[3-(Hydroxyimino)butan-2-ylidene]- 4-methylbenzene-1-sulfonohydrazide

Siqueira, Maria Carolina Bulhosa; Gervini, Vanessa Carratu; Oliveira, Leandro; Locatelli, Aline; Oliveira, Adriano Bof de
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
35.67%
In the title compound, C11H15N3O3S, the C-S-N(H)-N linkage is nonplanar, the torsion angle being 75.70 (12)°. The compound has two almost planar fragments linked to the S atom: the hydrazone-derivative fragment [(HONC4H6)N-N(H)-] and the tolyl fragment (C7H7-) have maximum deviations from the mean plane through the non-H atoms of 0.0260 (10) and 0.0148 (14) Å, respectively. The two planar fragments make an interplanar angle of 79.47 (5)°. In the crystal, molecules are connected through inversion centers via pairs of N-H...O and O-H...N hydrogen bonds

Measurement of the form factors of the decay B^+\to\bar D^{*0}\ell^+\nu_\ell and determination of the CKM matrix element |V_{cb}|

The Belle Collaboration
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/10/2009
Relevância na Pesquisa
35.78%
We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ times the form factor normalization $\mathcal{F}(1)$ using the decay $B^+\to\bar D^{*0}\ell^+\nu_\ell$. This measurement is performed together with a determination of the form factor parameters $\rho^2$, $R_1(1)$ and $R_2(1)$ which fully characterize this decay in the framework of Heavy Quark Effective Theory. This analysis is based on a data sample equivalent to 140 fb$^{-1}$ of Belle data collected near the $\Upsilon(4S)$ resonance. The preliminary results, based on about 27,000 reconstructed $B^+\to\bar D^{*0}\ell^+\nu_\ell$ decays, are $\rho^2=1.376\pm 0.074\pm 0.056$, $R_1(1)=1.620\pm 0.091\pm 0.092$, $R_2(1)=0.805\pm 0.064\pm 0.036$ and $\mathcal{F}(1)|V_{cb}|=35.0\pm 0.4\pm 2.2$. We find the $B^+\to\bar D^{*0}\ell^+\nu_\ell$ branching fraction to be $(4.84\pm 0.04\pm 0.56)%$. For all numbers quoted here, the first error is the statistical and the second is the systematic uncertainty. A direct, model-independent determination of the form factor shapes has also been carried out and shows good agreement with the HQET based form factor parametrization by Caprini {\it et al.}.; Comment: 22 pages, 8 figures

The environmental dependence of galaxy colors in intermediate redshift X-ray-selected clusters

Wake, David A.; Collins, Chris A.; Nichol, Robert C.; Jones, Laurence R.; Burke, Douglas. J.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 22/03/2005
Relevância na Pesquisa
35.7%
We present a wide-field imaging study of the colors of bright galaxies in 12 X-ray selected clusters and groups of galaxies at z ~ 0.3. The systems cover one of the largest ranges in X-ray luminosity (Lx ~ 10^43 - 10^45 erg/s), and hence mass, of any sample studied at this redshift. We find that the `red' galaxies form a tight color-magnitude relation (CMR) and that neither the slope nor zero-point of this relation changes significantly over the factor of 100 in X-ray luminosity of our sample. Using stellar population synthesis models we find our data allow a maximum possible change of 2 Gyrs in the typical age of the galaxies on the CMR over the range of Lx of our sample. We also measure the fraction of blue galaxies (fb) relative to the CMR in our clusters and find a low value of fb ~ 0.1 and find that there is no correlation between fb and Lx over our large Lx range. However, both the CMR and fb do depend on cluster radius, with the zero-point of the CMR shifting blueward in B-R by 0.10 +/- 0.036 magnitudes out to 0.75 times the virial radius, equivalent to a luminosity weighted age gradient of ~ 2.5 Gyrs per log(radius). It thus appears that the global cluster environment, in the form of cluster mass (Lx), has little influence on the properties of bright cluster galaxies...

Study of Broad Scale Anisotropy of Cosmic Ray Arrival Directions from $2\times 10^{17} eV$ to $10^{20} eV$ from Fly's Eye Data

Dai, H. Y.; Dawson, B. R.; Elbert, J. W.; Huang, M. A.; Kieda, D. B.; Ko, S.; Loh, E. C.; Luo, M.; Smith, J. D.; Sokolsky, P.; Sommers, P.; Thomas, S. B.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/06/1998
Relevância na Pesquisa
35.63%
We report results on the broad scale anisotropy of cosmic ray arrival directions in the energy rage from $2 \times 10^{17} eV$ to $10^{20} eV$. The data was taken by the Fly's Eye detector in both monocular and stereo modes of operation. We look for dependence on galactic latitude or supergalactic latitude by fitting the data to a Wdowczyk and Wolfendale plane enhancement function and a N-S gradient functional form. We report a small but statistically significant galactic plane enhancement in the energy range between $2\times 10^{17}eV$ and $3.2 \times 10^{18} eV$. The probability that this anisotropy is due to fluctuations of an isotropic distribution is less than 0.06%. The most significant galactic plane enhancement factor $f_{E} = 0.104 \pm 0.036$ is in the energy range $0.4-1.0 \times 10^{18} eV$. No statistically significant evidence for a N-S gradient is found. There is no sign of significant deviation from isotropic background when the data is analyzed in terms of supergalactic latitude distributions; Comment: 26 pages in Latex plus 11 figures in PS files

Fine-structure Constant, Anomalous Magnetic Moment, Relativity Factor and the Golden Ratio that Divides the Bohr Radius

Heyrovska, R.; Narayan, S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/09/2005
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Sommerfeld introduced the fine-structure constant into physics, while he was taking into account the relativistic effects in the theory of the hydrogen atom. Ever since, it has puzzled many scientists like Eddington, Dirac, Feynman and others. Here the mysterious fine-structure constant, alpha = (Compton wavelength/de Broglie wavelength) = 1/137.036 = 2.627/360 is interpreted based on the finding that it is close to 2.618/360 = 1/137.508, where the Compton wavelength for hydrogen is a distance equivalent to an arc length on the circumference (given by the de Broglie wavelength) of a circle with the Bohr radius and 2.618 is the square of the Golden ratio, which was recently shown to divide the Bohr radius into two Golden sections at the point of electrical neutrality. From the data for the electron (e) and proton (p) g-factors, it is found that (137.508 - 137.036)= 0.472 = [g(p) - g(e)]/[g(p) + g(e)] (= 2/cube of the Golden ratio), and that (2.627 - 2.618)/360 = (small part of the Compton wavelength corresponding to the intrinsic radii of e and p/de Broglie wavelength) = 0.009/360 = (1- gamma)/gamma, the factor for the advance of perihilion in Sommerfeld's theory of the hydrogen atom, where gamma is the relativity factor.; Comment: 8 pages including 1 figure