5,480 research outputs found
Extension of the C star rotation curve of the Milky Way to 24 kpc
Demers and Battinelli published, in 2007 the rotation curve of the Milky Way
based on the radial velocity of carbon stars outside the Solar circle. Since
then we have established a new list of candidates for spectroscopy. The goal of
this paper is to determine the rotation curve of the galaxy, as far as possible
from the galactic center, using N type carbon stars. The stars were selected
from their dereddened 2MASS colours, then the spectra were obtained with the
Dominion Astrophysical Observatory and Asiago 1.8 meter telescopes. This
publication adds radial velocities and Galactrocentric distances of 36 carbon
stars, from which 20 are new confirmed. The new results for stars up to 25 kpc
from the galactic center, suggest that the rotation curve shows a slight
decline beyond the Solar circle.Comment: 13 pages, 3 figures, 1 table; accepted for publication in
Astrophysic
The extent of NGC 6822 revealed by its C stars population
Using the CFH12K camera, we apply the four band photometric technique to
identify 904 carbon stars in an area 28' x 42' centered on NGC 6822. A few C
stars, outside of this area were also discovered with the Las Campanas Swope
Telescope. The NGC 6822 C star population has an average I of 19.26 mag leading
to an average absolute I magnitude of
-4.70 mag, a value essentially identical to the mean magnitude obtained for
the C stars in IC 1613. Contrary to stars highlighting the optical image of NGC
6822, C stars are seen at large radial distances and trace a huge slightly
elliptical halo which do not coincide with the huge HI cloud surrounding
NGC6822. The previously unknown stellar component of NGC 6822 has a exponential
scale length of 3.0' +/- 0.1' and can be traced to five scale lengths. The C/M
ratio of NGC 6822 is evaluated to br 1.0 +/- 0.2.Comment: accepted, to be published in A
Molecular Realization of a Quantum NAND Tree
The negative-AND (NAND) gate is universal for classical computation making it
an important target for development. A seminal quantum computing algorithm by
Farhi, Goldstone and Gutmann has demonstrated its realization by means of
quantum scattering yielding a quantum algorithm that evaluates the output
faster than any classical algorithm. Here, we derive the NAND outputs
analytically from scattering theory using a tight-binding (TB) model and show
the restrictions on the TB parameters in order to still maintain the NAND gate
function. We map the quantum NAND tree onto a conjugated molecular system, and
compare the NAND output with non-equilibrium Green's function (NEGF) transport
calculations using density functional theory (DFT) and TB Hamiltonians for the
electronic structure. Further, we extend our molecular platform to show other
classical gates that can be realized for quantum computing by scattering on
graphs.Comment: 17 pages, 6 figures, 1 tabl
Project Inclusive Genetics: Protecting Reproductive Autonomy From Bias via Prenatal Patient-Centered Counseling
Clinician bias negatively impacts the healthcare received by marginalized communities. In this study, we explored factors that influence clinician and trainee bias against individuals with intellectual disabilities and its impact on clinical judgment in prenatal genetic testing settings. Specifically, we examined bias toward a fetus with a higher chance of developing a disability. We compared genetics specialists with their non-expert counterparts. This web-based study included clinical vignettes, implicit association tests (IATs), and an educational module. 595 participants were recruited via their institution or professional society. We conducted statistical analyses, including regression models controlling for key demographic characteristics, to analyze recommendation patterns and degree of change after the module. Genetics expertise strongly correlated with appropriate testing recommendation when the patient would not consider pregnancy termination (r = 1.784 pre-module, r = 1.502 post-module, p \u3c 0.01). Factors that influenced pre-module recommendation to test include increased age (r = -0.029, p \u3c 0.05), high religiosity (r = 0.525, p \u3c 0.05), and participant personal preference against testing (r = 1.112, p \u3c 0.01). Responses among participants without genetics expertise improved after the educational module
Au-Ag template stripped pattern for scanning probe investigations of DNA arrays produced by Dip Pen Nanolithography
We report on DNA arrays produced by Dip Pen Nanolithography (DPN) on a novel
Au-Ag micro patterned template stripped surface. DNA arrays have been
investigated by atomic force microscopy (AFM) and scanning tunnelling
microscopy (STM) showing that the patterned template stripped substrate enables
easy retrieval of the DPN-functionalized zone with a standard optical
microscope permitting a multi-instrument and multi-technique local detection
and analysis. Moreover the smooth surface of the Au squares (abput 5-10
angstrom roughness) allows to be sensitive to the hybridization of the
oligonucleotide array with label-free target DNA. Our Au-Ag substrates,
combining the retrieving capabilities of the patterned surface with the
smoothness of the template stripped technique, are candidates for the
investigation of DPN nanostructures and for the development of label free
detection methods for DNA nanoarrays based on the use of scanning probes.Comment: Langmuir (accepted
A straightforward method for stereospecific assignment of val and leu prochiral methyl groups by solid-state NMR: Scrambling in the [2-13C]Glucose labeling scheme.
The unambiguous stereospecific assignment of the prochiral methyl groups in Val and Leu plays an important role in the structural investigation of proteins by NMR. Here, we present a straightforward method for their stereospecific solid-state NMR assignment based on [2-13C]Glucose ([2-13C]Glc) as the sole carbon source during protein expression. The approach is fundamentally based on the stereo-selective biosynthetic pathway of Val and Leu, and the co-presence of [2-13C]pyruvate produced mainly by glycolysis and [3-13C]/[1,3-13C]pyruvate most probably formed through scrambling in the pentose phosphate pathway. As a consequence, the isotope spin pairs 13Cβ-13Cγ2 and 13Cα-13Cγ1 in Val, and 13Cγ-13Cδ2 and 13Cβ-13Cδ1 in Leu are obtained. The approach is successfully demonstrated with the stereospecific assignment of the methyl groups of Val and Leu of type 3 secretion system PrgI needles and microcrystalline ubiquitin
Smartphone scene generator for efficient characterization of visible imaging detectors
Full characterization of imaging detectors involves subjecting them to
spatially and temporally varying illumination patterns over a large dynamic
range. Here we present a scene generator that fulfills many of these functions.
Based on a modern smartphone, it has a number of good features, including the
ability to generate nearly arbitrary optical scenes, high spatial resolution
(13 um), high dynamic range (~10^4), near-Poisson limited illumination
stability over time periods from 100 ms to many days, and no background noise.
The system does not require any moving parts and may be constructed at modest
cost. We present the optical, mechanical, and software design, test data
validating the performance, and application examples.Comment: 14 pages. This version includes code, available here:
https://github.com/Leo-Nea
- …