115,176 research outputs found
Targeted deep surveys of high Galactic latitude HI with the GBT
Over 800 sq. deg. of high Galactic latitude sky have been mapped at 21 cm
with the Robert C. Byrd Green Bank Telescope (GBT). An improved knowledge of
the telescope's beam characteristics has allowed us to reliably map not only
regions of high column density, but also such regions as ELAIS N1, a targeted
Spitzer field, which have very low HI column density. The additional fields we
have observed cover a cross-section of dynamically and chemically interesting
regions as indicated by the presence of intermediate/high velocity gas and/or
anomalous far-IR (dust) colour.Comment: 7 pages, 5 figures. To appear in "The Dynamic ISM: A celebration of
the Canadian Galactic Plane Survey" ASP Conference Serie
Aerodynamic design and analysis of the AST-204, AST-205, and AST-206 blended wing-fuse large supersonic transport configuration concepts
The aerodynamic design and analysis of three blended wing-fuselage supersonic cruise configurations providing four, five, and six abreast seating was conducted using a previously designed supersonic cruise configuration as the baseline. The five abreast configuration was optimized for wave drag at a Mach number of 2.7. The four and six abreast configurations were also optimized at Mach 2.7, but with the added constraint that the majority of their structure be common with the five abreast configuration. Analysis of the three configurations indicated an improvement of 6.0, 7.5, and 7.7 percent in cruise lift-to-drag ratio over the baseline configuration for the four, five, and six abreast configurations, respectively
Aerodynamic design and analysis of the AST-200 supersonic transport configuration concept
The design and analysis of a supersonic transport configuration was conducted using linear theory methods in conjunction with appropriate constraints. Wing optimization centered on the determination of the required twist and camber and proper integration of the wing and fuselage. Also included in the design are aerodynamic refinements to the baseline wing thickness distribution and nacelle shape. Analysis to the baseline and revised configurations indicated an improvement in lift-to-drag ratio of 0.36 at the Mach 2.7 cruise condition. Validation of the design is planned through supersonic wing tunnel tests
Tunneling Spectroscopy of Two-level Systems Inside Josephson Junction
We consider a two-level (TL) system with energy level separation Omega_0
inside a Josephson junction. The junction is shunted by a resistor R and is
current I (or voltage V = RI) biased. If the TL system modulates the Josephson
energy and/or is optically active, it is Rabi driven by the Josephson
oscillations in the running phase regime near the resonance 2eV = Omega_0. The
Rabi oscillations, in turn, translate into oscillations of current and voltage
which can be detected in noise measurements. This effect provides an option to
fully characterize the TL systems and to find the TL's contribution to the
decoherence when the junction is used as a qubit.Comment: 4 page
Modelling heat transfer through a novel design of rotary kiln
A novel form of rotary kiln has been developed which confers advantages over conventional designs. Details are given of the main features of the kiln, along with an approach used to study its heat transfer characteristics when hot processing waste products into a lightweight synthetic aggregate for recycling in building materials. Computer aided finite element modelling was used to predict temperature profiles and heat fluxes involving non-linear properties of the exterior insulation materials and internal radiation effects. Observations are given comparing predicted temperatures for two different cross sectional shapes and with those measured in practice on a prototype novel kiln. Observations are also given on the methods of approach to the modelling
Cryogenic seal remains leaktight during thermal displacement
Cryogenic seals protect the surfaces of a plastic member in a low-pressure system subjected to extreme temperature changes. The outer seal is an aluminum expansion ring bonded to the lens outer surface and the inner seal consists of a resin-filled aluminum U-ring bonded to the inner surface
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DNA Methylation Analysis Validates Organoids as a Viable Model for Studying Human Intestinal Aging.
Background & aimsThe epithelia of the intestine and colon turn over rapidly and are maintained by adult stem cells at the base of crypts. Although the small intestine and colon have distinct, well-characterized physiological functions, it remains unclear if there are fundamental regional differences in stem cell behavior or region-dependent degenerative changes during aging. Mesenchyme-free organoids provide useful tools for investigating intestinal stem cell biology in vitro and have started to be used for investigating age-related changes in stem cell function. However, it is unknown whether organoids maintain hallmarks of age in the absence of an aging niche. We tested whether stem cell-enriched organoids preserved the DNA methylation-based aging profiles associated with the tissues and crypts from which they were derived.MethodsTo address this, we used standard human methylation arrays and the human epigenetic clock as a biomarker of age to analyze in vitro-derived, 3-dimensional, stem cell-enriched intestinal organoids.ResultsWe found that human stem cell-enriched organoids maintained segmental differences in methylation patterns and that age, as measured by the epigenetic clock, also was maintained in vitro. Surprisingly, we found that stem cell-enriched organoids derived from the small intestine showed striking epigenetic age reduction relative to organoids derived from colon.ConclusionsOur data validate the use of organoids as a model for studying human intestinal aging and introduce methods that can be used when modeling aging or age-onset diseases in vitro
Entanglement of localized states
We derive exact expressions for the mean value of Meyer-Wallach entanglement
Q for localized random vectors drawn from various ensembles corresponding to
different physical situations. For vectors localized on a randomly chosen
subset of the basis, tends for large system sizes to a constant which
depends on the participation ratio, whereas for vectors localized on adjacent
basis states it goes to zero as a constant over the number of qubits.
Applications to many-body systems and Anderson localization are discussed.Comment: 6 pages, 4 figure
Three-Loop Mixing of Dipole Operators
We calculate the complete three-loop O(alpha_s^3) anomalous dimension matrix
for the dimension-five dipole operators that arise in the Standard Model after
integrating out the top quark and the heavy electroweak bosons. Our computation
completes the three-loop anomalous dimension matrix of operators that govern
low-energy |Delta F| = 1 flavor-changing processes, and represents an important
ingredient of the next-to-next-to-leading order QCD analysis of the Bbar -> X_s
gamma decay.Comment: 4 pages, 1 figure; journal version, text below Eq. (7) correcte
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