309 research outputs found
Dark-Matter Content of Early-Type Galaxies with Planetary Nebulae
No full textAbstract. We examine the dark matter properties of nearby early-type galaxies using plane-
tary nebulae (PNe) as mass probes. We have designed a specialised instrument, the Planetary
Nebula Spectrograph (PN.S) operating at the William Herschel telescope, with the purpose of
measuring PN velocities with best efficiency. The primary scientific objective of this custom-
built instrument is the study of the PN kinematics in 12 ordinary round galaxies. Preliminary
results showing a dearth of dark matter in ordinary galaxies (Romanowsky et al. 2003) are
now confirmed by the first complete PN.S datasets. On the other hand early-type galaxies with
a “regular” dark matter content are starting to be observed among the brighter PN.S target
sample, thus confirming a correlation between the global dark-to-luminous mass virial ratio
(fDM = MDM/M⋆) and the galaxy luminosity and mass.
DS_10.1177_1558944718812129 – Supplemental material for A Prospective, Randomized Trial Comparing Open and Endoscopic Carpal Tunnel Release Within the Same Patient
No full textSupplemental material, DS_10.1177_1558944718812129 for A Prospective, Randomized Trial Comparing Open and Endoscopic Carpal Tunnel Release Within the Same Patient by Brett M. Michelotti, Kavita T. Vakharia, Diane Romanowsky and Randy M. Hauck in HAND</p
Central mass-to-light ratios and dark matter fractions in early-type galaxies
No full textDynamical studies of local elliptical galaxies and the Fundamental Plane point to a strong dependence of the total mass-to-light ratio (M/L) on luminosity with a relation of the form M/L alpha L-gamma. The 'tilt' gamma may be caused by various factors, including stellar population properties (metallicity, age and star formation history), initial mass function, rotational support, luminosity profile non-homology and dark matter (DM)
fraction. We evaluate the impact of all these factors using a large
uniform data set of local early-type galaxies from Prugniel & Simien. We take particular care in estimating the stellar masses, using a general star formation history, and comparing different population synthesis models. We find that the stellar M/L contributes little to the tilt. We estimate the total M/L using simple Jeans dynamical models, and find that adopting accurate luminosity profiles is important but does not remove the
need for an additional tilt component, which we ascribe to DM. We survey trends of the DM fraction within one effective radius, finding it to be roughly constant for galaxies fainter than M-B similar to -20.5, and increasing with luminosity for the brighter galaxies; we detect no significant differences between S0s and fast- and slow-rotating ellipticals. We construct simplified cosmological mass models and find general consistency, where the DM transition point is caused by a change in the relation between luminosity and effective radius. A more refined
model with varying galaxy star formation efficiency suggests a transition from total mass profiles (including DM) of faint galaxies distributed similarly to the light to near-isothermal profiles for the bright galaxies. These conclusions are sensitive to various systematic uncertainties which we investigate in detail, but are consistent with the results of dynamical studies at larger radii
Stellar mass-to-light ratio gradients in galaxies: correlations with mass
No full textWe analyse the stellar mass-to-light ratio (M/L) gradients in a large sample of local galaxies taken from the Sloan Digital Sky Survey, spanning a wide range of stellar masses and morphological types. As suggested by the well-known relationship between M/L values and colours, we show that M/L gradients are strongly correlated with colour gradients, which we trace to the effects of age variations. Stellar M/L gradients generally follow patterns of variation with stellar mass and galaxy type that were previously found for colour and metallicity gradients. In late-type galaxies M/L gradients are negative, steepening with increasing mass. In early-type galaxies M/L gradients are shallower, while presenting a twofold trend: they decrease with mass up to a characteristic mass of ? and increase at larger masses. We compare our findings with other analyses and discuss some implications for galaxy formation and for dark matter estimates
VIMOS mosaic integral-field spectroscopy of the bulge and disc of the early-type galaxy NGC 4697
No full textThe use of the Penalized Pixel Fitting developed by Cappellari and Emsellem is gratefully acknowledged. Data were reduced using EsoRex and XSH pipeline by ESO Data Flow System Group. CS thanks S. C. Trager for the use of the code SPINDEX2 and C. Conroy for the precious help in understanding and using his stellar population models. CT has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 267251. We thank the referee for very constructive comments.We present an integral field study of the internal structure, kinematics and
stellar population of the almost edge-on, intermediate luminosity ()
elliptical galaxy NGC 4697. We build extended 2-dimensional (2D) maps of the
stellar kinematics and line-strengths of the galaxy up to effective
radii (R) using a mosaic of 8 VIMOS (VIsible Multi-Objects Spectrograph
on the VLT) integral-field unit pointings. We find clear evidence for a
rotation-supported structure along the major axis from the 2D kinematical maps,
confirming the previous classification of this system as a `fast-rotator'. We
study the correlations between the third and fourth Gauss-Hermite moments of
the line-of-sight velocity distribution (LOSVD) and with the
rotation parameter (), and compare our findings to hydrodynamical
simulations. We find remarkable similarities to predictions from gas-rich
mergers. Based on photometry, we perform a bulge/disk decomposition and study
the stellar population properties of the two components. The bulge and the disk
show different stellar populations, with the stars in the bulge being older
(age Gyr, ageGyr) and more metal-poor (, ). The
evidence of a later-formed, more metal-rich disk embedded in an older, more
metal-poor bulge, together with the LOSVD structure, supports a mass assembly
scenario dominated by gas-rich minor mergers and possibly with a late gas-rich
major merger that left a previously rapidly rotating system unchanged. The
bulge and the disk do not show signs of different stellar Initial Mass Function
slopes, and both match well with a Milky Way-like IMF
Confiabilidade da coloração hematológica rápida para citologia de escarro induzido
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Ciências Médicas, Florianópolis, 2013.Introdução: A análise do escarro induzido é importante na avaliação de condições inflamatórias das vias aéreas nas duas principais doenças respiratórias obstrutivas: asma e doença pulmonar obstrutiva crônica (DPOC). Devido à heterogeneidade das características clínicas e funcionais destas doenças, existe a necessidade de determinar o fenótipo clínico do paciente, para otimizar o seu manejo, especialmente nos casos mais graves. Contudo, o uso do escarro induzido na prática clínica ainda é restrito em virtude da metodologia envolvida na indução e processamento do escarro. Objetivos: determinar a confiabilidade da coloração hematológica rápida para a análise do escarro induzido, visando a diminuição do tempo e custo do processamento das amostras. Métodos: estudo transversal que compara a técnica de coloração May-Grünwald-Giemsa (considerada padrão) com a coloração hematológica rápida (corante Panótico Rápido). Participaram do estudo 50 indivíduos, sendo 21 portadores de asma, 19 portadores de DPOC e 10 indivíduos hígidos sem sintomas respiratórios. Após indução do escarro, foram geradas quatro citospinas, sendo duas coradas pela coloração padrão e duas pela coloração de estudo. As citospinas foram lidas independentemente por duas bioquímicas treinadas para leitura de escarro, estando as lâminas codificadas, impedindo a identificação dos respectivos pares de citospinas ou acesso a resultados anteriores. A confiabilidade do método foi avaliada pela concordância entre observadores e intra-observador para as contagens celulares resultantes dos dois métodos de coloração através do Coeficiente de Correlação Intraclasse (CCI) e a concordância da identificação de escarro neutrofílico e eosinofílico entre observadores e entre as duas colorações foi calculada através do Kappa estatístico. Resultados: O CCI apontou concordância quase perfeita entre os observadores para as contagens celulares de neutrófilos, eosinófilos e macrófagos para a coloração May-Grüwald-Giemsa e para a coloração hematológica rápida (CCI = 0,81-1,0). A concordância para as contagens de linfócitos entre observadores foi substancial para o corante May-Grüwald-Giemsa (CCI=0,76) e quase perfeita para a coloração hematológica rápida (CCI=0,83). O CCI mostrou uma concordância intra-observador quase perfeita para neutrófilos, eosinófilos e macrófagos. Para as contagens de linfócitos, o CCI apontou concordância substancial para um os dois observadores (CCI= 0,65 e 0,75). A concordância entre observadores na identificação de escarro eosinofílico e neutrofílico em citospinas coradas pelos doismétodos do estudo foi de substancial a quase perfeita (kappa = 0,75 ? 1,0). A concordância intra-observador, embora considerada substancial, foi inferior do que aquela entre observadores. Conclusão: A coloração hematológica rápida pode ser considerada alternativa confiável para o processamento das amostras de escarro induzido. Abstract : Introduction: Induced sputum analysis is an important tool to access inflammatory conditions of the airways in the main obstructive respiratory diseases: asthma and chronic obstructive pulmonary disease (COPD). The heterogeneity of functional and clinical characteristics in these diseases shows the need to determine the clinical phenotype for better clinical management, particularly in the more severe cases. However, the use of induced sputum in clinical practice is restricted, due to the complex methods involved in sputum induction and processing. Objectives: to determine the reliability of the use of a rapid hematologic stain in the analysis of induced sputum, in attempt to reduce the time and costs of sample processing. Methods: cross-sectional study to compare May-Grünwald-Giemsa staining (considered standard) to rapid hematologic staining (Diff-Quick). Fifty subjects were included in the study, 21 asthmatics, 19 patients with COPD and 10 healthy individuals without respiratory symptoms. After sputum induction, four slides were generated, two of them stained with May-Grüwald-Giemsa and the other two stained with rapid hematologic stain. The cytospins were independently counted by two biochemists qualified to sputum examination. The slides were coded preventing the identification of the respective pairs of slides or previous results. The reliability of the method was evaluated through intra-observer and inter-observer agreement between the cell counts obtained from the two staining methods, using the Intraclass Correlation Coefficient (ICC), and the agreement identifying neutrophilic or eosinophilic sputum was evaluated through kappa statistic. Results: ICCs indicated an almost perfect agreement between observers for the cell counts of neutrophils, eosinophils and macrophages for both staining techniques (ICC = 0,81 ? 1,0). The agreement between lymphocytes counts was substantial for May-Grünwald-Giemsa stain (ICC = 0,76) and almost perfect for the rapid hematologic stain (ICC = 0,83). Intra-observer agreement was almost perfect for neutrophils, eosinophils and macrophages counts. For lymphocyte counts the coefficient showed substantial agreement for both observers (ICC = 0,65 - 0,75). The agreement in identification of eosinophilic or neutrophilic sputum was from substantial to almost perfect (kappa = 0,75 ? 1,0). Although the intra-observer agreement was substantial, inter-observer agreement was higher. Conclusion: the rapid hematologic stain is reliable and can be considered suitable for sputum examination
Planetary Nebulae as Dynamical Tracers: Mass-to-Light-Ratio Gradients in Early-Type Galaxies
No full textPlanetary Nebulae (PNe) have enabled mass-to-light ratios (M/L) in early-type galaxies to be constrained to unprecedented distance from the center, showing in some cases clear evidence of increasing M/L, in other cases fairly constant M/L. We combine the information obtained from PN kinematics with radially extended long-slit spectroscopy data in order to constrain the M/L trends in a heterogeneous sample of early-type galaxies. We discuss whether these trends are expected in the Lambda CDM framework of galaxy formation.</p
Vertical distribution of caged estuarine fish in thermal effluent subject to gas supersaturation
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Bibliography: leaves 56-59.Not availabl
SPIDER - VI. The central dark matter content of luminous early-type galaxies: Benchmark correlations with mass, structural parameters and environment
No full textWe analyse the central dark-matter (DM) content of ∼4500 massive (M{black star} ≳ 1010M⊙), low-redshift (z < 0.1), early-type galaxies (ETGs), with high-quality ugrizY JHK photometry and optical spectroscopy from the Sloan Digital Sky Survey and the UKIRT Infrared Deep Sky Survey (UKIDSS). We estimate the 'central' fraction of DM within the K-band effective radius, Reff, using spherically symmetric isotropic galaxy models. We discuss the role of systematics in stellar mass estimates, dynamical modelling, and velocity dispersion anisotropy. The main results of the present work are the following: (1) DM fractions increase systematically with both structural parameters (i.e. Reff and Sérsic index, n) and mass proxies (central velocity dispersion, stellar and dynamical mass), as in previous studies, and decrease with central stellar density. (2) All correlations involving DM fractions are caused by two fundamental ones with galaxy effective radius and central velocity dispersion. These correlations are independent of each other, so that ETGs populate a central-DM plane (DMP), i.e. a correlation among fraction of total-to-stellar mass, effective radius, and velocity dispersion, whose scatter along the total-to-stellar mass axis amounts to ∼0.15 dex. (3) In general, under the assumption of an isothermal or a constant M/L profile for the total mass distribution, a Chabrier initial mass function (IMF) is favoured with respect to a bottom-heavier Salpeter IMF, as the latter produces negative (i.e. unphysical) DM fractions for more than 50 per cent of the galaxies in our sample. For a Chabrier IMF, the DM estimates agree with Λ cold dark matter toy-galaxy models based on contracted DM-halo density profiles. We also find agreement with predictions from hydrodynamical simulations. (4) The central DM content of ETGs does not depend significantly on the environment where galaxies reside, with group and field ETGs having similar DM trends. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS
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