590 research outputs found
Attitudes Toward Breast Cancer Genetic Testing in Five Special Population Groups
Purpose: This study examined interest in and attitudes toward genetic testing in 5 different population groups.
Methods: The survey included African American, Asian American, Latina, Native American, and Appalachian women with varying familial histories of breast cancer. A total of 49 women were interviewed in person. Descriptive and nonparametric statistical techniques were used to assess ethnic group differences.
Results: Overall, interest in testing was high. All groups endorsed more benefits than risks. There were group differences regarding endorsement of specific benefits and risks: testing to “follow doctor recommendations” (p=0.017), “concern for effects on family” (p=0.044), “distrust of modern medicine” (p=0.036), “cost” (p=0.025), and “concerns about communication of results to others” (p=0.032). There was a significant inverse relationship between interest and genetic testing cost (p
Conclusion: Cost may be an important barrier to obtaining genetic testing services, and participants would benefit by genetic counseling that incorporates the unique cultural values and beliefs of each group to create an individualized, culturally competent program. Further research about attitudes toward genetic testing is needed among Asian Americans, Native Americans, and Appalachians for whom data are severely lacking. Future study of the different Latina perceptions toward genetic testing are encouraged
Radial distribution of stars, gas and dust in SINGS galaxies. I. Surface photometry and morphology
We present ultraviolet through far-infrared surface brightness profiles for
the 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). The
imagery used to measure the profiles includes GALEX UV data, optical images
from KPNO, CTIO and SDSS, near-IR data from 2MASS, and mid- and far-infrared
images from Spitzer. Along with the radial profiles, we also provide
multi-wavelength asymptotic magnitudes and several non-parametric indicators of
galaxy morphology: the concentration index (C_42), the asymmetry (A), the Gini
coefficient (G) and the normalized second-order moment of the brightest 20% of
the galaxy's flux (M_20). Our radial profiles show a wide range of morphologies
and multiple components (bulges, exponential disks, inner and outer disk
truncations, etc.) that vary not only from galaxy to galaxy but also with
wavelength for a given object. In the optical and near-IR, the SINGS galaxies
occupy the same regions in the C_42-A-G-M_20 parameter space as other normal
galaxies in previous studies. However, they appear much less centrally
concentrated, more asymmetric and with larger values of G when viewed in the UV
(due to star-forming clumps scattered across the disk) and in the mid-IR (due
to the emission of Polycyclic Aromatic Hydrocarbons at 8.0 microns and very hot
dust at 24 microns).Comment: 66 pages in preprint format, 14 figures, published in ApJ. The
definitive publisher authenticated version is available online at
http://dx.doi.org/10.1088/0004-637X/703/2/156
A unified approach for the solution of the Fokker-Planck equation
This paper explores the use of a discrete singular convolution algorithm as a
unified approach for numerical integration of the Fokker-Planck equation. The
unified features of the discrete singular convolution algorithm are discussed.
It is demonstrated that different implementations of the present algorithm,
such as global, local, Galerkin, collocation, and finite difference, can be
deduced from a single starting point. Three benchmark stochastic systems, the
repulsive Wong process, the Black-Scholes equation and a genuine nonlinear
model, are employed to illustrate the robustness and to test accuracy of the
present approach for the solution of the Fokker-Planck equation via a
time-dependent method. An additional example, the incompressible Euler
equation, is used to further validate the present approach for more difficult
problems. Numerical results indicate that the present unified approach is
robust and accurate for solving the Fokker-Planck equation.Comment: 19 page
Chemical abundance patterns in the inner Galaxy: the Scutum Red Supergiant Clusters
The location of the Scutum Red-Supergiant (RSG) clusters at the end of the
Galactic Bar makes them an excellent probe of the Galaxy's secular evolution;
while the clusters themselves are ideal testbeds in which to study the
predictions of stellar evolutionary theory. To this end, we present a study of
the RSGs' surface abundances using a combination of high-resolution H-band
spectroscopy and spectral synthesis analysis. We provide abundance measurements
for elements C, O, Si, Mg, Ti, and Fe. We find that the surface abundances of
the stars studied are consistent with CNO burning and deep, rotationally
enhanced mixing. The average a/Fe ratios of the clusters are solar, consistent
with a thin-disk population. However, we find significantly sub-solar Fe/H
ratios for each cluster, a result which strongly contradicts a simple
extrapolation of the Galactic metallicity gradient to lower Galacto-centric
distances. We suggest that a simple one-dimensional parameterization of the
Galaxy's abundance patterns is insufficient at low Galactocentric distances, as
large azimuthal variations may be present. Indeed, we show that the abundances
of O, Si and Mg are consistent with independent measurements of objects in
similar locations in the Galaxy. In combining our results with other data in
the literature, we present evidence for large-scale (~kpc) azimuthal variations
in abundances at Galacto-centric distances of 3-5kpc. While we cannot rule-out
that this observed behaviour is due to systematic offsets between different
measurement techniques, we do find evidence for similar behaviour in a study of
the barred-spiral galaxy NGC4736 which uses homogeneous methodology. We suggest
that these azimuthal abundance variations could result from the intense but
patchy star formation driven by the potential of the central bar.Comment: 13 pages, 9 figures, accepted to Ap
MAXI J1659-152: The shortest orbital period black-hole transient in outburst
MAXI J1659-152 is a bright X-ray transient black-hole candidate binary system
discovered in September 2010. We report here on MAXI, RXTE, Swift, and
XMM-Newton observations during its 2010/2011 outburst. We find that during the
first one and a half week of the outburst the X-ray light curves display drops
in intensity at regular intervals, which we interpret as absorption dips. About
three weeks into the outbursts, again drops in intensity are seen. These dips
have, however, a spectral behaviour opposite to that of the absorption dips,
and are related to fast spectral state changes (hence referred to as transition
dips). The absorption dips recur with a period of 2.414+/-0.005 hrs, which we
interpret as the orbital period of the system. This implies that MAXI J1659-152
is the shortest period black-hole candidate binary known to date. The
inclination of the accretion disk with respect to the line of sight is
estimated to be 65-80 degrees. We propose the companion to the black-hole
candidate to be close to an M5 dwarf star, with a mass and radius of about
0.15-0.25 M_sun and 0.2-0.25 R_sun, respectively. We derive that the companion
had an initial mass of about 1.5 M_sun, which evolved to its current mass in
about 5-6 billion years. The system is rather compact (orbital separation of
larger than ~1.33 R_sun), and is located at a distance of 8.6+/-3.7 kpc, with a
height above the Galactic plane of 2.4+/-1.0 kpc. The characteristics of short
orbital period and high Galactic scale height are shared with two other
transient black-hole candidate X-ray binaries, i.e., XTE J1118+480 and Swift
J1735.5-0127. We suggest that all three are kicked out of the Galactic plane
into the halo, rather than being formed in a globular cluster.Comment: 20 pages, 14 figures, accepted for publication in A&
Patterning graphene nanostripes in substrate-supported functionalized graphene: A promising route to integrated, robust, and superior transistors
It is promising to apply quantum-mechanically confined graphene systems in
field-effect transistors. High stability, superior performance, and large-scale
integration are the main challenges facing the practical application of
graphene transistors. Our understandings of the adatom-graphene interaction
combined with recent progress in the nanofabrication technology indicate that
very stable and high-quality graphene nanostripes could be integrated in
substrate-supported functionalized (hydrogenated or fluorinated) graphene using
electron-beam lithography. We also propose that parallelizing a couple of
graphene nanostripes in a transistor should be preferred for practical
application, which is also very useful for transistors based on graphene
nanoribbon.Comment: Frontiers of Physics (2012) to be publishe
Star formation in the extended gaseous disk of the isolated galaxy CIG 96
We study the Kennicutt-Schmidt star formation law and efficiency in the
gaseous disk of the isolated galaxy CIG 96 (NGC 864), with special emphasis on
its unusually large atomic gas (HI) disk (r_HI/r_25 = 3.5, r_25 = 1.'85). We
present deep GALEX near and far ultraviolet observations, used as a recent star
formation tracer, and we compare them with new, high resolution (16", or 1.6
kpc) VLA HI observations. The UV and HI maps show good spatial correlation
outside the inner 1', where the HI phase dominates over H_2. Star-forming
regions in the extended gaseous disk are mainly located along the enhanced HI
emission within two (relatively) symmetric giant gaseous spiral arm-like
features, which emulate a HI pseudo-ring at a r \simeq 3' . Inside such
structure, two smaller gaseous spiral arms extend from the NE and SW of the
optical disk and connect to the previously mentioned HI pseudo-ring.
Interestingly, we find that the (atomic) Kennicutt-Schmidt power law index
systematically decreases with radius, from N \simeq 3.0 +- 0.3 in the inner
disk (0.'8 - 1.'7) to N = 1.6 +- 0.5 in the outskirts of the gaseous disk (3.'3
- 4.'2). Although the star formation efficiency (SFE), the star formation rate
per unit of gas, decreases with radius where the HI component dominates as is
common in galaxies, we find that there is a break of the correlation at r = 1.5
r_25. At radii 1.5 r_25 < r < 3.5 r_25, mostly within the HI pseudo-ring
structure, there exist regions whose SFE remains nearly constant, SFE \simeq
10^-11 yr^-1. We discuss about possible mechanisms that might be triggering the
star formation in the outskirts of this galaxy, and we suggest that the
constant SFE for such large radii r > 2 r_25 and at such low surface densities
might be a common characteristic in extended UV disk galaxies.Comment: 12 pages, 7 figures, 1 table. Accepted for publication in Ap
The Star Formation History and Dust Content in the Far Outer Disc of M31
We present a detailed analysis of two fields located 26 kpc (~5 scalelengths)
from the centre of M31. One field samples the major axis populations--the Outer
Disc field--while the other is offset by ~18' and samples the Warp in the
stellar disc. The CMDs based on HST/ACS imaging reach old main-sequence
turn-offs (~12.5 Gyr). We apply the CMD-fitting technique to the Warp field to
reconstruct the star formation history (SFH). We find that after undergoing
roughly constant SF until about 4.5 Gyr ago, there was a rapid decline in
activity and then a ~1.5 Gyr lull, followed by a strong burst lasting 1.5 Gyr
and responsible for 25% of the total stellar mass in this field. This burst
appears to be accompanied by a decline in metallicity which could be a
signature of the inflow of metal-poor gas. The onset of the burst (~3 Gyr ago)
corresponds to the last close passage of M31 and M33 as predicted by detailed
N-body modelling, and may have been triggered by this event. We reprocess the
deep M33 outer disc field data of Barker et al. (2011) in order to compare
consistently-derived SFHs. This reveals a similar duration burst that is
exactly coeval with that seen in the M31 Warp field, lending further support to
the interaction hypothesis. The complex SFHs and the smoothly-varying
age-metallicity relations suggest that the stellar populations observed in the
far outer discs of both galaxies have largely formed in situ rather than
migrated from smaller galactocentric radii. The strong differential reddening
affecting the CMD of the Outer Disc field prevents derivation of the SFH.
Instead, we quantify this reddening and find that the fine-scale distribution
of dust precisely follows that of the HI gas. This indicates that the outer HI
disc of M31 contains a substantial amount of dust and therefore suggests
significant metal enrichment in these parts, consistent with inferences from
our CMD analysis.Comment: Abstract shortened. 17 pages, 12 figures (+ 6 pages & 5 figures in
Appendix). MNRAS, in pres
Enhanced Efficacy of the CDNF/MANF Family by Combined Intranigral Overexpression in the 6-OHDA Rat Model of Parkinson's Disease
Cerebral Dopamine Neurotrophic Factor (CDNF) and Mesencephalic Astrocyte-derived Neurotrophic factor (MANF) are members of a recently discovered family of neurotrophic factors (NTFs). Here, we used intranigral or intrastriatal lentiviral vector-mediated expression to evaluate their efficacy at protecting dopaminergic function in the 6-OHDA model of Parkinson's disease (PD). In contrast to the well-studied Glial-Derived Neurotrophic Factor (GDNF), no beneficial effects were demonstrated by striatal overexpression of either protein. Interestingly, nigral overexpression of CDNF decreased amphetamine-induced rotations and increased tyroxine hydroxylase (TH) striatal fiber density but had no effect on numbers of TH(+) cells in the SN. Nigral MANF overexpression had no effect on amphetamine-induced rotations or TH striatal fiber density but resulted in a significant preservation of TH(+) cells. Combined nigral overexpression of both factors led to a robust reduction in amphetamine-induced rotations, greater increase in striatal TH-fiber density and significant protection of TH(+) cells in the SN. We conclude that nigral CDNF and MANF delivery is more efficacious than striatal delivery. This is also the first study to demonstrate that combined NTF can have synergistic effects that result in enhanced neuroprotection, suggesting that multiple NTF delivery may be more efficacious for the treatment of PD than the single NTF approaches attempted so far.Molecular Therapy (2014); doi:10.1038/mt.2014.206
- …