1,367 research outputs found
Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
We present empirical color transformations between the Sloan Digital Sky
Survey (SDSS) ugriz photometry and Johnson-Cousins UBVRI system and Becker's
RGU system, respectively. Owing to the magnitude of data that is becoming
available in the SDSS photometric system it is particularly important to be
able to convert between this new system and traditional photometric systems.
Unlike earlier published transformations we based our calculations on stars
actually measured by the SDSS with the SDSS 2.5-m telescope. The photometric
database of the SDSS provides in a sense a single-epoch set of 'tertiary
standards' covering more than one quarter of the sky. Our transformations
should facilitate their use to easily and reliably derive the corresponding
approximate Johnson-Cousins or RGU magnitudes. The SDSS survey covers a number
of areas that were previously established as standard fields in the
Johnson-Cousins system, in particular, fields established by Landolt and by
Stetson. We used these overlapping fields to create well-photometered star
samples on which our calculated transformations are based. For the RGU
photometry we used fields observed in the framework of the new Basel
high-latitude field star survey. We calculated empirical color transformations
between SDSS photometry and Johnson-Cousins UBVRI and Becker's RGU system. For
all transformations we found linear relations to be sufficient. Furthermore we
showed that the transformations between the Johnson-Cousins and the SDSS system
have a slight dependence on metallicity.Comment: 11 pages, 7 figures, Accepted for publication in A&
Influence of Mindfulness Practice on Counseling Skills Development
This study assessed the impact of mindfulness practice, incorporated alongside a five-week counselor skills training model, on the counseling skills development of masterâs-level trainees (N = 59). Three groups of counseling students were studied: those who engaged in no mindfulness practice; those who engaged in a brief amount of mindfulness practice (five mindfulness practice sessions); and those who engaged in an extended amount of mindfulness practice (11 mindfulness practice sessions). The results showed improvements in counseling skills associated with mindfulness practice, although the brief and extended intervention groups did not significantly differ from one another
Evidence-based management options for women at increased breast/ovarian cancer risk
Recent developments in our ability to predict breast cancer risk necessitates primary care physicians learn to evaluate breast cancer risk and its importance in shaping decisions concerning surveillance and risk reduction measures. This article reviews the current opinion on risk assessment and management of women with an increased risk of breast/ovarian cancer. Management options are given for women at slightly, moderately and highly elevated breast cancer risk, as well as for BRCA1/2 carriers, based on currently available evidenc
Understanding Womenâs Experiences of Defending Against Eating Disorder Symptoms: An Interpretive Phenomenological Analysis
Initial Mass Function Effects on the Colour Evolution of Disk Galaxies
Aims. In this work, we want to find out if the IMF can be determined from colour images, integrated colours, or mass-to-light ratios, especially at high redshift, where galaxies cannot be resolved into individual stars, which would enable us to investigate dependencies of the IMF on cosmological epoch.
Methods. We use chemo-dynamical models to investigate the influence of the Initial Mass Function (IMF) on the evolution of a Milky Way-type disk galaxy, in particular of its colours.
Results. We find that the effect of the IMF on the internal gas absorption is larger than its effect on the light from the stellar content. However, the two effects work in the opposite sense: An IMF with more high mass stars leads to brighter and bluer star-light, but also to more interstellar dust and thus to more absorption, causing a kind of âIMF degeneracyâ. The most likely wavelength region in which to detect IMF effects is the infrared (i.e., JHK). We also provide photometric absorption and inclination corrections in the SDSS ugriz and the HST WFPC2 and NICMOS systems
Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations
We have assembled a spectroscopic sample of low-mass dwarfs observed as part
of the Sloan Digital Sky Survey along one Galactic sightline, designed to
investigate the observable properties of the thin and thick disks. This sample
of ~7400 K and M stars also has measured ugriz photometry, proper motions, and
radial velocities. We have computed UVW space motion distributions, and
investigate their structure with respect to vertical distance from the Galactic
Plane. We place constraints on the velocity dispersions of the thin and thick
disks, using two-component Gaussian fits. We also compare these kinematic
distributions to a leading Galactic model. Finally, we investigate other
possible observable differences between the thin and thick disks, such as
color, active fraction and metallicity.Comment: 11 pages, 12 figures, Accepted by A
Breast cancer: Pretreatment drug resistance parameters (GSH-system, ATase, P-glycoprotein) in tumor tissue and their correlation with clinical and prognostic characteristics
Background: The identification of new factors predicting relapse, outcome and response to systemic therapy in breast cancer is warranted. The measurement of biological markers such as drug resistance parameters (DRPs), which are part of the phenotype of malignant cells and contribute to resistance to anti-cancer drugs may be a possibility, which may ultimately lead to improvement of therapeutic results. Patients and methods: The level of glutathione (GSH), activities of glutathione-S-transferase (GST), glutathione-peroxidase (GPx), 06-alkylguanine-DNA-alkyltransferase (ATase), and P-glycoprotein (PGP) were measured in tumor and adjacent tumor free tissue samples from 89 consecutive, untreated females with breast cancer and correlated with clinical and prognostic factors. Early breast cancer (EBC) was diagnosed in 56 patients, 22 patients had locally advanced (LABC) and 11 patients metastatic breast cancer. Results: All DRPs showed significantly higher expression in tumor than in tumor free tissues. GPx was positively correlated with GST (r = 0.3, P = 0.0048) and with GSH (r = 0.5, P = 0.0001) in tumor as well as in normal tissue. GST activity was significantly higher in EBC than in LABC or metastatic breast cancer (P = 0.02). GSH level was significantly higher in grade I than in grade 2 or grade 3 tumors (P = 0.01). When clinical characteristics were related to the level of DRP, âhigh' GSH was associated with age >60 years (P = 0.01) in EBC, and with grade 1-2 tumors (P = 0.05) in LABC. No differences in OS were apparent between groups of âhigh' and âlow' DRP-expression. However, the four-year estimated disease-free survival of EBC tended to be higher in patients with âhigh' GST (P = 0.10) and of LABC in patients with âhigh' GPx levels (P = 0.06). Conclusion: We conclude that âhigh' levels of DRP in tumor tissue of breast cancer patients are part of the initial phenotype of the malignant cells. Due to its high prevalence (83% in EBC, 100% in primarily metastatic breast cancer), PGP did not add to prognostic information. High levels of GSH, GST and and GPx were associated with favorable clinical characteristics and good prognosis, whereas low levels of GSH and GST activity were associated with more aggressive or more advanced diseas
Uncertainty-principle noise in vacuum-tunneling transducers
The fundamental sources of noise in a vacuum-tunneling probe used as an
electromechanical transducer to monitor the location of a test mass are
examined using a first-quantization formalism. We show that a tunneling
transducer enforces the Heisenberg uncertainty principle for the position and
momentum of a test mass monitored by the transducer through the presence of two
sources of noise: the shot noise of the tunneling current and the momentum
fluctuations transferred by the tunneling electrons to the test mass. We
analyze a number of cases including symmetric and asymmetric rectangular
potential barriers and a barrier in which there is a constant electric field.
Practical configurations for reaching the quantum limit in measurements of the
position of macroscopic bodies with such a class of transducers are studied
XMM-Newton Optical Monitor observations of LMC X-3
We study the optical counterpart of the black-hole X-ray binary LMC X-3, by
using XMM-Newton/OM observations carried out during a low-hard X-ray state. We
derive a better constraint for the temperature, mass and radius of the
companion star, and we show that the star is likely to be a ~ B5 subgiant
filling its Roche lobe. Taking into account the effect of X-ray irradiation, we
suggest a value f_M = (1.5 +/- 0.3) M_sun for the mass function in this system,
lower than previously thought; we provide a more accurate lower limit to the
mass of the compact object.Comment: accepted for publication in the special XMM-Newton issue of A&A
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