Radial Velocity Confirmation of a Binary Detected from Pulse Timings

A periodic variation in the pulse timings of the pulsating hot subdwarf B star CS 1246 was recently discovered via the O-C diagram and suggests the presence of a binary companion with an orbital period of two weeks. Fits to this phase variation, when interpreted as orbital reflex motion, imply CS 1246 orbits a barycenter 11 light-seconds away with a velocity of 16.6 km/s. Using the Goodman spectrograph on the SOAR telescope, we decided to confirm this hypothesis by obtaining radial velocity measurements of the system over several months. Our spectra reveal a velocity variation with amplitude, period, and phase in accordance with the O-C diagram predictions. This corroboration demonstrates that the rapid pulsations of hot subdwarf B stars can be adequate clocks for the discovery of binary companions via the pulse timing method.Comment: Accepted for publication in ApJ Letters; 5 pages, 2 figures, 3 tables; uses emulateap

Molecular Feshbach dissociation as a source for motionally entangled atoms

We describe the dissociation of a diatomic Feshbach molecule due to a time-varying external magnetic field in a realistic trap and guide setting. An analytic expression for the asymptotic state of the two ultracold atoms is derived, which can serve as a basis for the analysis of dissociation protocols to generate motionally entangled states. For instance, the gradual dissociation by sequences of magnetic field pulses may delocalize the atoms into macroscopically distinct wave packets, whose motional entanglement can be addressed interferometrically. The established relation between the applied magnetic field pulse and the generated dissociation state reveals that square-shaped magnetic field pulses minimize the momentum spread of the atoms. This is required to control the detrimental influence of dispersion in a recently proposed experiment to perform a Bell test in the motion of the two atoms [C. Gneiting and K. Hornberger, Phys. Rev. Lett. 101, 260503 (2008)].Comment: 12 pages, 3 figures; corresponds to published versio

Making a House a Home: A Community Plan for Regional Engagement on Housing

This plan was developed for Virginia Organizing, a statewide non-partisan grassroots organization dedicated to challenging injustice by empowering local communities. The plan was designed to produce a replicable model for organizers embarking on housing campaigns. Research on the Virginia Organizing chapters in Fredericksburg and Charlottesville was completed as well as on the broader affordable housing ecosystems in these regions. This research was gathered through interviews with regional and local planners, organizers, non-profit representatives, and individuals working in the intersection of planning and organizing. Chapter member research, which guided this plan, was conducted through surveying, focus groups, and qualitative mapping. Findings focused on regionalism, internal and external capacity, time and expectations, and power and roles. The plan utilized best practices in Richmond, Virginia and Washington, D.C. combined with chapter research to produce the replicable model and recommendations. The replicable model suggests increasingly difficult campaign goals based on the level of capacity in the region. Plan implementation addresses the chapter, non-profit ecosystem, and broader community involved in housing. This plan was produced in the belief that everyone must be included in moving from policy to action

Olefin polymerisation using titanium phosphinimide catalysts.

Homopolymers of 1-hexene, random copolymers of 1-hexene and 1,5-hexadiene, and block copolymers of ethylene and 1-hexene have been prepared at sub-ambient temperatures using Cp(tBu3PN)TiMe2 ( 34) and studied. In addition, the polymerisation of 1-hexene by ( 34) has been investigated for its potential as a living polymerisation system. Analysis of the poly(1-hexene) produced by (34) via 13C NMR spectroscopy reveals that the polymer contains an unusually high degree of 2,1 enchainments, with approximately one in five insertions being reversed relative to the previous one. This suggests that the coordination sphere in (34) is more open than in metallocene catalysts. However, despite the increased openness and ability to insert alpha-olefins in a 2,1 fashion, the internal olefins cyclopentene and cis -2-pentene could not be polymerised to an appreciable extent using (34). A series of copolymers of 1-hexene and 1,5-hexadiene were prepared using (34), with varying amounts of 1,5-hexadiene in the monomer feedstock. (Abstract shortened by UMI.)Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2003 .C57. Source: Masters Abstracts International, Volume: 44-01, page: 0362. Thesis (M.Sc.)--University of Windsor (Canada), 2003

Planar laser-induced fluorescence imaging of OH in the exhaust of a bi-propellant thruster

Planar laser-induced fluorescence imaging of the hydroxyl radical has been performed on the flow produced by the exhaust of a subscale H2/O2 fueled bi-propellant rocket engine. Measurements were made to test the feasibility of OH (0,0) and (3,0) excitation strategies by using injection seeded XeCl and KrF excimer lasers, respectively. The flow is produced with hydrogen and oxygen reacting at a combustor chamber pressure of 5 atm which then exhausts to the ambient. The hydroxyl concentration in the exhaust flow is approximately 8 percent. Fluorescence images obtained by pumping the Q1(3) transition in the (0,0) band exhibited very high signals but also showed the effect of laser beam absorption. To obtain images when pumping the P1(8) transition in the (3,0) band it was necessary to use exceptionally fast imaging optics and unacceptably high intensifier gains. The result was single-shot images which displayed a signal-to-noise ratio of order unity or less when measured on a per pixel basis

Maternal cell-free DNA-based screening for fetal microdeletion and the importance of careful diagnostic follow-up.

BackgroundNoninvasive prenatal screening (NIPS) by next-generation sequencing of cell-free DNA (cfDNA) in maternal plasma is used to screen for common aneuploidies such as trisomy 21 in high risk pregnancies. NIPS can identify fetal genomic microdeletions; however, sensitivity and specificity have not been systematically evaluated. Commercial companies have begun to offer expanded panels including screening for common microdeletion syndromes such as 22q11.2 deletion (DiGeorge syndrome) without reporting the genomic coordinates or whether the deletion is maternal or fetal. Here we describe a phenotypically normal mother and fetus who tested positive for atypical 22q deletion via maternal plasma cfDNA testing.MethodsWe performed cfDNA sequencing on saved maternal plasma obtained at 11 weeks of gestation from a phenotypically normal woman with a singleton pregnancy whose earlier screening at a commercial laboratory was reported to be positive for a 22q11.2 microdeletion. Fluorescence in situ hybridization and chromosomal microarray diagnostic genetic tests were done postnatally.ConclusionNIPS detected a 22q microdeletion that, upon diagnostic workup, did not include the DiGeorge critical region. Diagnostic prenatal or postnatal testing with chromosomal microarray and appropriate parental studies to determine precise genomic coordinates and inheritance should follow a positive microdeletion NIPS result

Influence of Noise on Force Measurements

We demonstrate how the ineluctable presence of thermal noise alters the measurement of forces acting on microscopic and nanoscopic objects. We quantify this effect exemplarily for a Brownian particle near a wall subjected to gravitational and electrostatic forces. Our results demonstrate that the force measurement process is prone to artifacts if the noise is not correctly taken into account.Comment: 4 Pages, 4 Figures, Accepte