Página 2 dos resultados de 178 itens digitais encontrados em 0.001 segundos

Influência da contaminação por saliva durante a realização de procedimentos adesivos; Influence of saliva contamination during adhesive procediments

Kawaguchi, Fernando Aparecido
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/07/2009 Português
Relevância na Pesquisa
17.1%
O objetivo deste estudo foi avaliar a influência da contaminação com saliva em diferentes momentos do procedimento operatório, bem como diferentes tratamentos desta contaminação. Este estudo foi conduzido utilizando estudo de resistência adesiva (RA), através de ensaio de microtração, com avaliação do padrão de fratura. Foram utilizados 120 molares humanos (n=10). Os dois substratos do teste foram obtidos a partir da mesma unidade amostral. Os grupos experimentais para ambos os substratos foram: sem contaminação (controle G1 e G13); contaminação antes do condicionamento ácido (CAC), com lavagem e secagem (G2 e G14); secagem apenas (G3 e G15); contaminação após o condicionamento ácido (CAC), com lavagem e secagem (G4 e G16); secagem apenas (G5 e G17); CDC e recondicionamento para repetição da técnica adesiva (G6 e G18); contaminação entre as duas camadas de adesivo (CEA), com lavagem e secagem (G7 e G19); secagem apenas (G8 e G20); CEA e recondicionamento (G9 e G21); contaminação após a aplicação final do sistema adesivo (CFA), com lavagem e secagem (G10 e G22); secagem apenas (G11 e G23); CFA e recondicionamento (G12 e G24). O adesivo utilizado foi o Adper Single Bond 2 (SB2) e a resina composta Z-250 (3M) para a realização do teste de microtração. Os resultados foram submetidos ao teste de ANOVA demonstrando que existe influencia da contaminação com saliva na RA de esmalte (p=0...

Avaliação histoquímica, imuno-histoquímica e morfométrica do plexo mioentérico do jejuno e do colo de ratos Wistar durante o desenvolvimento pós-natal; Histochemical, immunohistochemical and morphometric evaluation of the myenteric plexus of jejunum and colon in Wistar rats during postnatal development

Arango, Lynda Jhailú Tamayo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/03/2010 Português
Relevância na Pesquisa
18.13%
O objetivo desta pesquisa foi quantificar os neurônios mioentéricos do jejuno e do colo durante o desenvolvimento pós-natal de ratos Wistar utilizando morfometria com enfoque estereológico e analisar as mudanças na área ocupada por neurônios e axônios mediante Sistemas de Informação Geográfica (SIG). Foram usadas 20 fêmeas de ratos da linhagem Wistar, divididas em grupos de acordo com a idade pós-natal em dias (G0, G7, G21 e G60). A análise morfométrica foi realizada em preparados totais de membrana usando azul cuprolínico, histoquímica para acetilcolinesterase (AChE) e NADPH-diaforase (NADPH-d), e imuno-histoquímicas para VIP e substância P. Foram estimadas a densidade numérica neuronal/área de superfície serosa, o número total de neurônios por segmento e a área neuronal média. A análise da área ocupada por neurônios e axônios foi realizada a partir de imagens de NADPH-d e AChE. Ocorreu uma diminuição significativa na densidade neuronal/área, nos neurônios totais e nos neurônios nitrérgicos a partir de G7 no jejuno e de G0 no colo, e nos neurônios colinérgicos entre G0 e G7 no jejuno e G0 e G21 no colo. O número total de neurônios corados com azul cuprolínico aumentou significativamente no colo a partir de G7; houve aumento dos neurônios nitrérgicos entre G7 e G21 e nos neurônios colinérgicos entre G21 e G60. No jejuno somente houve aumento do número total de neurônios nitrérgicos entre G0 e G7. Também foi percebido um aumento significativo na área dos neurônios nitrérgicos a partir de G7 no jejuno e de G0 no colo...

Diferentes frações inspiradas de oxigênio em coelhos hipovolêmicos anestesiados com propofol e submetidos à ventilação mecânica

Borges, Paula Araceli; Nunes, Newton; Camacho, Aparecido Antonio; Batista, Priscila Andrea Costa dos Santos; Gava, Fábio Nelson; Bürger, Camila Paes; Moro, Juliana Vitti; Lopes, Patrícia Cristina Ferro
Fonte: Universidade Federal de Santa Maria (UFSM) Publicador: Universidade Federal de Santa Maria (UFSM)
Tipo: Artigo de Revista Científica Formato: 1960-1966
Português
Relevância na Pesquisa
17.1%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Avaliaram-se os efeitos do fornecimento de diferentes frações inspiradas de oxigênio (FiO²) em coelhos hipovolêmicos, anestesiados com infusão contínua de propofol e mantidos em ventilação controlada sobre os parâmetros respiratórios, hemogasométricos e hemodinâmicos. Foram utilizados 50 coelhos (Nova Zelândia), pesando 3,5±0,3kg, distribuídos em 5 grupos: G100 (FiO²=1), G80 (FiO²=0,8), G60 (FiO²=0,6), G40 (FiO²=0,4) e G21 (FiO²=0,21), os quais receberam xilazina (1mg kg-1) e cetamina (15mg kg-1) pela via intramuscular. Transcorridos 20 minutos, foi administrado propofol (8mg kg-1 bolus e 0,5mg kg-1 min-1) e rocurônio (0,6mg kg-1 bolus e 0,6mg kg-1 h-1). Iniciou-se então, a ventilação mecânica no modo pressão controlada. Após 30 minutos, os animais foram submetidos à hipovolemia aguda, retirando-se sangue arterial (12mL kg-1). Os parâmetros foram mensurados 30 minutos após a indução anestésica (M0) e a cada dez minutos depois da exsanguinação (M1- M7). As variáveis foram submetidas à análise de variância seguida pelo teste de Tukey (P<0,05). Os valores de PaO², SaO², P A O², AaDO² diminuíram quanto mais baixas foram as FiO². Após a indução da hipovolemia...

Estudo de diferentes frações inspiradas de oxigênio em coelhos induzidos à hipovolemia aguda, anestesiados com propofol e submetidos à ventilação controlada a pressão

Borges, Paula Araceli
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: xxxiv, 105 f.
Português
Relevância na Pesquisa
17.1%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Pós-graduação em Cirurgia Veterinária - FCAV; Avaliaram-se os efeitos do fornecimento de diferentes frações inspiradas de oxigênio (FiO2) em coelhos hipovolêmicos anestesiados com infusão contínua de propofol e mantidos em ventilação controlada sobre os parâmetros respiratórios, hemogasométricos e hemodinâmicos. Foram utilizados 50 coelhos (Nova Zelândia), pesando 3,5±0,8kg, distribuídos em 5 grupos: G100 (FiO2=1), G80 (FiO2=0,8), G60 (FiO2=0,6), G40 (FiO2=0,4) e G21 (FiO2=0,21), os quais receberam xilazina (1mg/Kg) e cetamina (15mg/Kg) pela via intramuscular. Transcorridos 20 minutos, foi administrado propofol (8mg/kg bolus e 0,5mg/kg/min) e rocurônio (0,6mg/kg bolus e 0,6mg/kg/h). Iniciou-se então, a ventilação mecânica no modo pressão controlada. Após 40 minutos, os animais foram submetidos à hipovolemia aguda, retirando-se sangue arterial (12mL/kg). Os parâmetros foram mensurados 40 minutos após a indução anestésica (M0), dez minutos após a indução da hipovolemia (M1), seguindo-se de novas mensurações a cada dez minutos (M2 a M5). As variáveis foram submetidas à análise de variância seguida pelo teste de Tukey (p<0,05). Os valores de PaO2...

Turnover do carbono (δ13c) em linhagens de frangos de corte tipo colonial

Araujo, Priscila Cavalca de
Fonte: Universidade Estadual Paulista (UNESP) Publicador: Universidade Estadual Paulista (UNESP)
Tipo: Tese de Doutorado Formato: xii, 106 f. : il.,grafs, tabs.
Português
Relevância na Pesquisa
17.1%
Pós-graduação em Zootecnia - FMVZ; Este trabalho teve como objetivo avaliar o turnover do carbono-13 no músculo peitoral e quilha de três linhagens de frango tipo colonial Máster Griss, Vermelhão Pesado e Label Rouge, em diferentes fases de crescimento. Foram alojados 768 pintos de um dia de idade, divididos em 6 grupos (G). Para avaliar o turnover nos tecidos, o grupo G0-21 recebeu dieta composta predominantemente por plantas do ciclo C3, os demais grupos tiveram a dieta C4 substituída pela dieta C3 aos 7 (G7-35), 14(G14-49); 21(G21-63), 28 (G28-84) e 35(G35-119) dias de idade. Foram coletadas amostras de músculo peitoral e quilha de 4 aves/grupo nos dias de coleta das aves tiveram suas dietas previamente substituídas para a determinação das razões isotópicas de carbono em espectrômetro de massa. Para mensurar a velocidade de substituição do carbono depois de determinado intervalo de tempo (turnover), foi empregada função exponencial de tempo obtida através do método de equações exponenciais de primeira ordem do softwareOriginPro®8 Professional. A Linhagem Label Rouge, apresenta maior turnover do carbono nos tecidos analisados comparado com as demais linhagens. A idade e os tecidos analisados influenciaram o turnover de carbono-13...

Determinants of outstanding mortgage loan to value ratios: evidence from the netherlands

Cunha, M. Ricardo; Lambrecht, Bart M.; Pawlina, Grzegorz
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
16.53%
This paper studies the determinants and behavior of outstanding mortgage loan to value (LTV) ratios for a panel data set of 5,179 households over the period 1992-2005. We find that outstanding LTVs are driven by household characteristics, life-cycle effects and mortgage type characteristics. LTV declines with the time elapsed since mortgage commencement, but its level is consistently higher (by around 10%) for non-repayment mortgages (such as interest-only or endowment mortgages) than for repayment mortgages (such as linear or annuity mortgages). The difference results from higher debt capacity associated with the possibility of deferring the principal repayment for non-repayment mortgages. Our results indicate that the recent proliferation of non-repayment mortgages is driven by tightening financing constraints due to declining affordability in the housing market and that the overall quality of outstanding mortgages has substantially deteriorated over the last decade.

Primary Production and Nutrient Content in Two Salt Marsh

Neves, JP; Ferreira, LF; Simões, MP; Gazarini, LC
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica Formato: 12662 bytes; application/pdf
Português
Relevância na Pesquisa
17.59%
Seasonal variation patterns of aboveground and belowground biomass, net primary production, and nutrient accumulation were assessed in Atriplex portulacoides L. and Limoniastrum monopetalum (L.) Boiss. in Castro Marim salt marsh, Portugal. Sampling was conducted for five periods during 2001–2002 (autumn, winter, spring, summer, and autumn). This study indicates that both species have a clear seasonal variation pattern for both aboveground and belowground biomass. Mean live biomass was 2516 g m22 yr21 for L. monopetalum and 598 g m22 yr21 for A. portulacoides. Peak living biomass, in spring for both species, was three times greater in the former, 3502 g m22 yr21, than in the latter, 1077 g m22 yr21. For both the Smalley (Groenendijk 1984) and Weigert and Evans (1964) methods, productivity of L. monopetalum (2917 and 3635 g m22 yr21, respectively) was greater than that of A. portulacoides (1002 and 1615 g m22 yr21, respectively). Belowground biomass of L. monopetalum was 1.7 times greater than that of A. portulacoides. In spite of this, the root:shoot ratio for A. portulacoides was greater throughout the year. This shows that A. portulacoides allocates more biomass to roots and L. monopetalum to aerial components. Leaf area index was similar for both species...

Chromosomal localization of human genes governing the interferon-induced antiviral state.

Chany, C; Vignal, M; Couillin, P; Van Cong, N; Boué, J; Boué, A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1975 Português
Relevância na Pesquisa
17.1%
Interferon sensitivity of different normal and aneusomic human cells and of different mouse-human hybrids cells has been compared. G21 trisomic cells are more sensitive than diploid cells; whereas, on the contrary, triploid cells are normal in their human interferon sensitivity. Among other aneusomic cell lines tested, E16 trisomic cells are significantly less sensitive. These data are in favor of the hypotheses that the G21 chromosome carries genetic information for structural proteins involved in the receptor system for interferon, that there is a regulatory mechanism governing the antiviral state, and that the E16 chromosome is a possible candidate for carrying information for such a depressive regulatory mechanism. None of the chromosome abnormalities studies are involved with interferon synthesis.

Premeiotic and Meiotic Instability Generates Numerous b2 Mutation Derivatives in Ascobolus

Nicolas, A.; Hamza, H.; Mekki-Berrada, A.; Kalogeropoulos, A.; Rossignol, J. L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/1987 Português
Relevância na Pesquisa
17.4%
We have studied the genetic characteristics of an unstable mutation located in the central region of the b2 gene of the fungus Ascobolus. In crosses to wild type, this spontaneous white ascospore mutation (G0 ) gives rise to a stable white spored derivative (G1) at a frequency of 5 x 10-3. G1 is a frameshift mutation and differs from G0 by its gene conversion pattern. In self crosses, G0 gives asci with colored spore derivatives at a frequency of 1 x 10-3. We isolated and analyzed genetically 97 independent colored derivatives ("G2" series). All but one are pseudorevertants. By the criteria of phenotype and gene conversion pattern with wild type and with G1, the pseudorevertants represent at least 13 distinct classes. Two of them are large silent deletion mutations. In crosses with wild type, some G2 derivatives, represented by G21, continue to exhibit instability, G21 yields white spored b2 mutant derivatives at a frequency of 2.6 x 10-3. In turn, some of these "G3" mutants are themselves unstable. All the derivatives lie at the same site within the b2 locus as the parental mutation G0 . Different mutations in the G series manifest their instability at different times in the Ascobolus life cycle. Derivatives of G0 arise premeiotically (leading to two derivative meiotic products among the four)...

VULNERABILITY OF MACAQUE CRANIAL NERVE NEURONS TO ETHANOL IS TIME AND SITE-DEPENDENT

Mooney, Sandra M.; Miller, Michael W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.1%
The present study tested the hypotheses that vulnerability to ethanol depends upon (1) population-based characteristics of the neuronal progenitors and (2) the maturation of that population by examining the effects of prenatal exposure to ethanol on brainstem nuclei derived from different rhombomeres and from the alar and basal plates. Macaca nemestrina received an ethanol-containing solution one day per week during the first six (Et6) or 24 (Et24) weeks of gestation. Control animals received an equivalent volume of saline. The treatment regime for some animals included early gastrulation (gestational day (G) 19 or G20), whereas others were treated later (on G21 or G24). Brainstems were cryosectioned and stained with cresyl violet. Stereological methods were used to determine the numbers of neurons in six different nuclei: the abducens (VI), vagal (X), and hypoglossal (XII) motor nuclei and sensory components of the trigeminal brainstem nuclear complex (the principal (PSN), oral (SpVo), and interpolar (SpVi) subnuclei). There were no differences in the numbers of neurons in any of the nuclei between controls or Et6- and Et24-treated monkeys. In contrast, the number of trigeminal sensory neurons was significantly (p<0.05) lower in animals treated on G19/G20 than in control. No differences between controls and monkeys treated on G21/G24 were detected. No motor nuclei exhibited an ethanol-induced change. These data together with data on the trigeminal motor nucleus show that vulnerability to ethanol (1) is greater in sensory nuclei than in motor nuclei and (2) is temporally restricted to the time of gastrulation.

Effect of ageing on left ventricular compliance and distensibility in healthy sedentary humans

Fujimoto, Naoki; Hastings, Jeffrey L; Bhella, Paul S; Shibata, Shigeki; Gandhi, Nainesh K; Carrick-Ranson, Graeme; Palmer, Dean; Levine, Benjamin D
Fonte: Blackwell Science Inc Publicador: Blackwell Science Inc
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.1%
Healthy, but sedentary ageing leads to marked atrophy and stiffening of the heart, with substantially reduced cardiac compliance; but the time course of when this process occurs during normal ageing is unknown. Seventy healthy sedentary subjects (39 female; 21–77 years) were recruited from the Dallas Heart Study, a population-based, random community sample and enriched by a second random sample from employees of Texas Health Resources. Subjects were highly screened for co-morbidities and stratified into four groups according to age: G21−34: 21–34 years, G35−49: 35–49 years, G50−64: 50–64 years, G≥65: ≥65 years. All subjects underwent invasive haemodynamic measurements with right heart catheterization to define Starling and left ventricular (LV) pressure–volume curves. LV end-diastolic volumes (EDV) were measured by echocardiography at baseline, −15 and −30 mmHg lower-body negative pressure, and 15 and 30 ml kg−1 saline infusion with simultaneous measurements of pulmonary capillary wedge pressure. There were no differences in heart rate or blood pressures among the four groups at baseline. Baseline EDV index was smaller in G≥65 than other groups. LV diastolic pressure–volume curves confirmed a substantially greater LV compliance in G21−34 compared with G50−64 and G≥65...

La finance islamique: fondements, theorie et realite.

MARTENS, André
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica Formato: 212633 bytes; application/pdf
Português
Relevância na Pesquisa
17.1%
L’Islam interdit le riba , mot arabe signifiant à la fois usure et intérêt. L’interdiction du rib figure dans la loi islamique, née dans l’Arabie du Moyen Âge. Elle est à la base de la finance islamique qui connut une expansion remarquable durant la deuxième moitié du XX e siècle. Nous nous interrogeons sur les origines de cette interdiction, sur les problèmes que connaît actuellement la finance islamique et sur ses perspectives d’avenir.; The practice of riba (« usury » or « interest » in Arabic) is forbidden by Islam. This prohibition is inscribed in Islamic Law originating during the Middle Ages in The Arab Peninsula. It is at the core of what is called « Islamic finance », having had a remarkable expansion in the second part of the twentieth century. This article focuses on the origin of riba prohibition, the problems facing Islamic finance at the eve of the third millennium and the development prospects of Islamic financial institutions. Key words : riba , usury, Islamic finance, economic development

Environmental Risks : Should Banks Be Liable?

GOBERT, Karine; POITEVIN, Michel
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica Formato: 864510 bytes; application/pdf
Português
Relevância na Pesquisa
17.1%
This paper studies the impact of banks' liability for environmental damages caused by their borrowers. Laws or court decisions that declare banks liable for environmental damages have two objectives : (1) finding someone to pay for the damages and (2) exerting a pressure on a firm's stakeholders to incite them to invest in environmental risk prevention. We study the effect that such legal decisions can have on financing relationships and especially on the incentives to reduce environmental risk in an environment where banks cannot commit to refinance the firm in all circumstances. Following an environmental accident, liable banks more readily agree to refinance the firm. We then show that bank liability effectively makes refinancing more attractive to banks, therefore improving the firm's risk-sharing possibilities. Consequently, the firm's incentives to invest in environmental risk reduction are weakened compared to the (bank) no-liability case. We also show that, when banks are liable, the firm invests at the full-commitment optimal level of risk reduction investment. If there are some externalities such that some damages cannot be accounted for, the socially efficient level of investment is greater than the privately optimal one. in that case...

Environmental Risk: Should Banks Be Liable?

GOBERT, Karine; POITEVIN, Michel
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica Formato: 864510 bytes; application/pdf
Português
Relevância na Pesquisa
17.1%
This paper studies the impact of banks' liability for environmental damages caused by their borrowers. Laws or court decisions that declare banks liable for environmental damages have two objectives : (1) finding someone to pay for the damages and (2) exerting a pressure on a firm's stakeholders to incite them to invest in environmental risk prevention. We study the effect that such legal decisions can have on financing relationships and especially on the incentives to reduce environmental risk in an environment where banks cannot commit to refinance the firm in all circumstances. Following an environmental accident, liable banks more readily agree to refinance the firm. We then show that bank liability effectively makes refinancing more attractive to banks, therefore improving the firm's risk-sharing possibilities. Consequently, the firm's incentives to invest in environmental risk reduction are weakened compared to the (bank) no-liability case. We also show that, when banks are liable, the firm invests at the full-commitment optimal level of risk reduction investment. If there are some externalities such that some damages cannot be accounted for, the socially efficient level of investment is greater than the privately optimal one. in that case...

Tissue Tropism of Enteropathogenic Escherichia coli Strains Belonging to the O55 Serogroup

Fitzhenry, R. J.; Reece, S.; Trabulsi, L. R.; Heuschkel, R.; Murch, S.; Thomson, M.; Frankel, G.; Phillips, A. D.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /08/2002 Português
Relevância na Pesquisa
17.4%
Four enteropathogenic Escherichia coli (EPEC) strains belonging to the O55 serogroup (G21 and G30 [both O55:H6], G35 [O55:H−], and G58 [O55:H7]) were tested for their tissue tropism by using human intestinal in vitro organ culture. Strains showed restricted adhesion with attaching-and-effacing activity to follicle-associated epithelium of Peyer's patches, with no apparent adhesion to duodenum or colon. G35 and G58 express intimin γ and show a similar tropism to intimin γ-expressing enterohemorrhagic E. coli (EHEC) O157:H7. However, strains G21 and G30 were unusual because they expressed intimin α and had a restricted tissue tropism of intimin γ phenotype. The amino acid sequence of the carboxy-terminal 280 amino acids of intimin from G21 was determined. Comparison with the prototype intimin α from strain E2348/69 (O127:H6) showed a single amino acid difference (corresponding to Val907 and Ala907 in the whole intimins). This mutation was reproduced by site-directed mutagenesis in an intimin α plasmid template, pCVD438, with the hypothesis that it may induce a change in tropism. However, when the mutated plasmid was placed in both EPEC and EHEC backgrounds, duodenal adhesion in a manner similar to strain E2348/69 was evident upon in vitro organ culture. Thus...

Les déterminants des faillites bancaires dans les pays en développement: le cas des pays de l'Union économique et monétaire Ouest-africaine (UEMOA)

POWO FOSSO, Bruno
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica Formato: 175606 bytes; application/pdf
Português
Relevância na Pesquisa
17.1%
L’objectif de ce papier est de déterminer les facteurs susceptibles d’expliquer les faillites bancaires au sein de l’Union économique et monétaire ouest-africaine (UEMOA) entre 1980 et 1995. Utilisant le modèle logit conditionnel sur des données en panel, nos résultats montrent que les variables qui affectent positivement la probabilité de faire faillite des banques sont : i) le niveau d’endettement auprès de la banque centrale; ii) un faible niveau de comptes disponibles et à vue; iii) les portefeuilles d’effets commerciaux par rapport au total des crédits; iv) le faible montant des dépôts à terme de plus de 2 ans à 10 ans par rapport aux actifs totaux; et v) le ratio actifs liquides sur actifs totaux. En revanche, les variables qui contribuent positivement sur la vraisemblance de survie des banques sont les suivantes : i) le ratio capital sur actifs totaux; ii) les bénéfices nets par rapport aux actifs totaux; iii) le ratio crédit total sur actifs totaux; iv) les dépôts à terme à 2 ans par rapport aux actifs totaux; et v) le niveau des engagements sous forme de cautions et avals par rapport aux actifs totaux. Les ratios portefeuilles d’effets commerciaux et actifs liquides par rapport aux actifs totaux sont les variables qui expliquent la faillite des banques commerciales...

Discovery of an absorbed cluster of galaxies (XMMU J183225.4-103645) close to the Galactic plane with XMM-Newton

Nevalainen, J.; Lumb, D.; Santos, S. dos; Siddiqui, H.; Stewart, G.; Parmar, A. N.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.1%
During an XMM-Newton observation of the galactic supernova remnant G21.5-09 a bright, previously uncatalogued, source (XMMU J183225.4-103645) was detected 18 arcmin from G21.5-09. The European Photon Imaging Camera data inside 1 arcmin (180/h_50 kpc) radius are consistent with a source at a redshift of 0.1242 [+0.0003, -0.0022] with an optically thin thermal spectrum of temperature 5.8 +- 0.6 keV and a metal abundance of 0.60 +- 0.10 solar. This model gives a 2 - 10 keV luminosity of 3.5[+0.8, -0.4]/h_50^2 10^44 erg/s. These characteristics, as well as the source extent of 2.0 arcmin (350/h_50 kpc), and the surface brightness profile are consistent with emission from the central region of a moderately rich cluster containing a cooling flow with mass flow rate of 400-600 M_Sun/yr. The absorption is 7.9 +- 0.5 10^22 atom/cm^2, 5 times that inferred from low-resolution HI data but consistent with higher spatial resolution infrared dust extinction estimates. XMMU J183225.4-103645 is not visible in earlier ROSAT observations due to high amount of absorption. This discovery demonstrates the capability of XMM-Newton to map the cluster distribution close to the Galactic plane, where few such systems are known. The ability of XMM-Newton to determine cluster redshifts to 1% precision at z = 0.1 is especially important in optically crowded and absorbed fields such as close to the Galactic plane...

Particle Transport in Young Pulsar Wind Nebulae

Tang, Xiaping; Chevalier, Roger A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
17.1%
The model for pulsar wind nebulae (PWNe) as the result of the magnetohydrodynamic (MHD) downstream flow from a shocked, relativistic pulsar wind has been successful in reproducing many features of the nebulae observed close to the central pulsars. However, observations of well-studied young nebulae like the Crab Nebula, 3C 58, and G21.5--0.9 do not show the toroidal magnetic field on a larger scale that might be expected in the MHD flow model; in addition, the radial variation of spectral index due to synchrotron losses is smoother than expected in the MHD flow model. We find that pure diffusion models can reproduce the basic data on nebular size and spectral index variation for the Crab, 3C 58, and G21.5--0.9. Most of our models use an energy independent diffusion coefficient; power law variations of the coefficient with energy are degenerate with variation in the input particle energy distribution index in the steady state, transmitting boundary case. Energy dependent diffusion is a possible reason for the smaller diffusion coefficient inferred for the Crab. Monte Carlo simulations of the particle transport allowing for advection and diffusion of particles suggest that diffusion dominates over much of the total nebular volume of the Crab. Advection dominates close to the pulsar and is likely to play a role in the X-ray half-light radius. The source of diffusion and mixing of particles is uncertain...

NuSTAR study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5-0.9

Nynka, Melania; Hailey, Charles J.; Reynolds, Stephen P.; An, Hongjun; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Grefenstette, Brian W.; Harrison, Fiona A.; Krivonos, Roman; Madsen, Kristin K.; M
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 13/05/2014 Português
Relevância na Pesquisa
27.1%
We present NuSTAR high energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5-0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies NuSTAR clearly detects non-thermal emission up to ~20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at ~9 keV that cannot be reproduced by current SED models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, $L(E) \propto E^{m}$ with $m = -0.21 \pm 0.01$. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel & Coroniti (1984). This value, along with the observed steepening in power-law index between radio and X-ray...

NuSTAR Study of Hard X-Ray Morphology and Spectroscopy of PWN G21.5–0.9

Nynka, Melania; Hailey, Charles J.; Reynolds, Stephen P.; An, Hongjun; Baganoff, Frederick K.; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.; Gotthelf, Eric V.; Grefenstette, Brian W.; Harrison, Fiona A.; Krivonos, Roman; Madsen, Kristin K.; M
Fonte: American Astronomical Society Publicador: American Astronomical Society
Tipo: Article; PeerReviewed Formato: application/pdf; application/pdf
Publicado em 01/07/2014 Português
Relevância na Pesquisa
27.1%
We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5−0.9. We detect integrated emission from the nebula up to ~40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to ~20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes. We detect a break in the spatially integrated X-ray spectrum at ~9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, L(E)∝E^(m) with m = −0.21 ± 0.01. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel & Coroniti. This value, along with the observed steepening in power-law index between radio and X-ray...