1,003 research outputs found
Implications for the origin of dwarf early-type galaxies: a detailed look at the isolated rotating dwarf early-type galaxy CG 611, with ramifications for the Fundamental Plane's (S_K)^2 kinematic scaling and the spin-ellipticity diagram
Selected from a sample of nine, isolated, dwarf early-type galaxies (ETGs)
having the same range of kinematic properties as dwarf ETGs in clusters, we use
CG 611 (LEDA 2108986) to address the Nature versus Nurture debate regarding the
formation of dwarf ETGs. The presence of faint disk structures and rotation
within some cluster dwarf ETGs has often been heralded as evidence that they
were once late-type spiral or dwarf irregular galaxies prior to experiencing a
cluster-induced transformation into an ETG. However, CG 611 also contains
significant stellar rotation (~20 km/s) over its inner half light radius,
R_(e,maj)=0.71 kpc, and its stellar structure and kinematics resemble those of
cluster ETGs. In addition to hosting a faint young nuclear spiral within a
possible intermediate-scale stellar disk, CG 611 has accreted an
intermediate-scale, counter-rotating gas disk. It is therefore apparent that
dwarf ETGs can be built by accretion events, as opposed to disk-stripping
scenarios. We go on to discuss how both dwarf and ordinary ETGs with
intermediate-scale disks, whether under (de)construction or not, are not fully
represented by the kinematic scaling S_0.5=sqrt{ 0.5(V_rot)^2 + sigma^2 }, and
we also introduce a modified spin-ellipticity diagram, lambda(R)-epsilon(R),
with the potential to track galaxies with such disks.Comment: 15 pages (includes 9 figures and an extensive 2+ page reference list
Analytical approximations of K-corrections in optical and near-infrared bands
To compare photometric properties of galaxies at different redshifts, the
fluxes need to be corrected for the changes of effective rest-frame wavelengths
of filter bandpasses, called K-corrections. Usual approaches to compute them
are based on the template fitting of observed spectral energy distributions
(SED) and, thus, require multi-colour photometry. Here, we demonstrate that, in
cases of widely used optical and near-infrared filters, K-corrections can be
precisely approximated as two-dimensional low-order polynomials of only two
parameters: redshift and one observed colour. With this minimalist approach, we
present the polynomial fitting functions for K-corrections in SDSS ugriz, UKIRT
WFCAM YJHK, Johnson-Cousins UBVR_cI_c, and 2MASS JHK_s bands for galaxies at
redshifts Z<0.5 based on empirically-computed values obtained by fitting
combined optical-NIR SEDs of a set of 10^5 galaxies constructed from SDSS DR7
and UKIDSS DR5 photometry using the Virtual Observatory. For luminous red
galaxies we provide K-corrections as functions of their redshifts only. In two
filters, g and r, we validate our solutions by computing K-corrections directly
from SDSS DR7 spectra. We also present a K-corrections calculator, a web-based
service for computing K-corrections on-line.Comment: 13 pages, 7 figures, 25 tables. Accepted for publication in MNRAS.
This version contains low-resolution figures. The "K-corrections calculator"
service is available at http://kcor.sai.msu.ru
Canonical NF-ÎșB signaling is uniquely required for the long-term persistence of functional mature B cells
Although canonical NF-ÎșB signaling is crucial to generate a normal mature B-cell compartment, its role in the persistence of resting mature B cells is controversial. To resolve this conflict, we ablated NF-ÎșB essential modulator (NEMO) and I{kappa}B kinase 2 (IKK2), two essential mediators of the canonical pathway, either early on in B-cell development or specifically in mature B cells. Early ablation severely inhibited the generation of all mature B-cell subsets, but follicular B-cell numbers could be largely rescued by ectopic expression of B-cell lymphoma 2 (Bcl2), despite a persisting block at the transitional stage. Marginal zone (MZ) B and B1 cells were not rescued, indicating a possible role of canonical NF-ÎșB signals beyond the control of cell survival in these subsets. When canonical NF-ÎșB signaling was ablated specifically in mature B cells, the differentiation and/or persistence of MZ B cells was still abrogated, but follicular B-cell numbers were only mildly affected. However, the mutant cells exhibited increased turnover as well as functional deficiencies upon activation, suggesting that canonical NF-ÎșB signals contribute to their long-term persistence and functional fitness
Previous Experiences with Epilepsy and Effectiveness of Information to Change Public Perception of Epilepsy
Differences with regard to the effectiveness of health information and attitude change are suggested between people with direct, behavioral experiences with a health topic and people with indirect, nonbehavioral experiences. The effects of three different methods of health education about epilepsy, frequently used in health education practice, are assessed in a pretest posttest design with control groups, controlling for experiences with epilepsy. Subjects were 132 students from teacher-training colleges. After all treatments, attitudes, and knowledge about epilepsy were changed in a positive way. Treatments were found to be equally effective. Before treatment, direct behavioral experiences were related to knowledge and a more positive attitude towards epilepsy. After treatment, subjects with direct behavioral experiences with epilepsy showed less change of attitude and knowledge as compared with subjects with indirect experiences. Direct experiences appear to restrain the processing of new information and attitude change
Evolution of dwarf early-type galaxies I. Spatially resolved stellar populations and internal kinematics of Virgo cluster dE/dS0 galaxies
Understanding the origin and evolution of dwarf early-type galaxies remains
an important open issue in modern astrophysics. Internal kinematics of a galaxy
contains signatures of violent phenomena which may have occurred, e.g. mergers
or tidal interactions, while stellar population keeps a fossil record of the
star formation history, therefore studying connection between them becomes
crucial for understanding galaxy evolution. Here, in the first paper of the
series, we present the data on spatially resolved stellar populations and
internal kinematics for a large sample of dwarf elliptical (dE) and lenticular
(dS0) galaxies in the Virgo cluster. We obtained radial velocities, velocity
dispersions, stellar ages and metallicities out to 1--2 half-light radii by
re-analysing already published long-slit and integral-field spectroscopic
datasets using the {\sc NBursts} full spectral fitting technique. Surprisingly,
bright representatives of the dE/dS0 class ( mag) look
very similar to intermediate-mass and giant lenticulars and ellipticals: (1)
their nuclear regions often harbour young metal-rich stellar populations always
associated with the drops in the velocity dispersion profiles; (2) metallicity
gradients in the main discs/spheroids vary significantly from nearly flat
profiles to -0.9 dex , i.e. somewhat 3 times steeper than for typical
bulges; (3) kinematically decoupled cores were discovered in 4 galaxies,
including two with very little, if any, large scale rotation. These results
suggest similarities in the evolutionary paths of dwarf and giant early-type
galaxies and call for reconsidering the role of major mergers in the dE/dS0
evolution.Comment: 22 pages, 3 tables, 29 figures, accepted to MNRA
Motor system hyperconnectivity in juvenile myoclonic epilepsy: a cognitive functional magnetic resonance imaging study
Juvenile myoclonic epilepsy is the most frequent idiopathic generalized epilepsy syndrome. It is characterized by predominant myoclonic jerks of upper limbs, often provoked by cognitive activities, and typically responsive to treatment with sodium valproate. Neurophysiological, neuropsychological and imaging studies in juvenile myoclonic epilepsy have consistently pointed towards subtle abnormalities in the medial frontal lobes. Using functional magnetic resonance imaging with an executive frontal lobe paradigm, we investigated cortical activation patterns and interaction between cortical regions in 30 patients with juvenile myoclonic epilepsy and 26 healthy controls. With increasing cognitive demand, patients showed increasing coactivation of the primary motor cortex and supplementary motor area. This effect was stronger in patients still suffering from seizures, and was not seen in healthy controls. Patients with juvenile myoclonic epilepsy showed increased functional connectivity between the motor system and frontoparietal cognitive networks. Furthermore, we found impaired deactivation of the default mode network during cognitive tasks with persistent activation in medial frontal and central regions in patients. Coactivation in the motor cortex and supplementary motor area with increasing cognitive load and increased functional coupling between the motor system and cognitive networks provide an explanation how cognitive effort can cause myoclonic jerks in juvenile myoclonic epilepsy. The supplementary motor area represents the anatomical link between these two functional systems, and our findings may be the functional correlate of previously described structural abnormalities in the medial frontal lobe in juvenile myoclonic epilepsy
Symptom Experience and Quality of Life of Women Following Breast Cancer Treatment
Background: Few studies have examined the correlates of breast cancer-related symptoms that persist posttreatment and determined the relationship between symptoms and quality of life (QOL). Methods: A population-based sample of women in the United States with stage 0âII breast cancer (n = 1372) completed a survey including the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire and the Breast Cancer-Specific Quality of Life Questionnaire. Described are the presence and frequency of 13 symptom scales and their associations with 10 QOL dimensions. Results: All study participants had completed primary treatment (surgery and radiation and/or chemotherapy, if applicable). Mean time from initial surgical treatment to completion of the questionnaire was 7.2 months (range 0.5â14.9 months). Mean number of symptoms reported was 6.8, with the 5 most common symptom scales being systemic therapy side effects (87.7%), fatigue (81.7%), breast symptoms (72.1%), sleep disturbance (57.1%), and arm symptoms (55.6%). Younger age and poorer health status at diagnosis were associated with worse symptoms. Fatigue had the greatest impact on QOL, with significant differences between those with high and low fatigue across 7 QOL dimensions. Sociodemographic, prior health status, clinical, and treatment/diagnostic factors explained only 9%â27% of the variance in QOL outcomes. Adding symptom experience increased the variance explained to 18%â60%. Conclusions: More attention to the reduction and management of disease and treatment-related symptoms could improve QOL among women with breast cancer.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63179/1/jwh.2006.0255.pd
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