3,562 research outputs found
Investigation of parabolic computational techniques for internal high-speed viscous flows
A feasibility study was conducted to assess the applicability of an existing parabolic analysis (ADD-Axisymmetric Diffuser Duct), developed previously for subsonic viscous internal flows, to mixed supersonic/subsonic flows with heat addition simulating a SCRAMJET combustor. A study was conducted with the ADD code modified to include additional convection effects in the normal momentum equation when supersonic expansion and compression waves were present. It is concluded from the present study that for the class of problems where strong viscous/inviscid interactions are present a global iteration procedure is required
Self-consistent massive disks in triaxial dark matter halos
Galactic disks in triaxial dark matter halos become deformed by the
elliptical potential in the plane of the disk in such a way as to counteract
the halo ellipticity. We develop a technique to calculate the equilibrium
configuration of such a disk in the combined disk-halo potential, which is
based on the method of Jog (2000) but accounts for the radial variation in both
the halo potential and the disk ellipticity. This crucial ingredient results in
qualitatively different behavior of the disk: the disk circularizes the
potential at small radii, even for a reasonably low disk mass. This effect has
important implications for proposals to reconcile cuspy halo density profiles
with low surface brightness galaxy rotation curves using halo triaxiality. The
disk ellipticities in our models are consistent with observational estimates
based on two-dimensional velocity fields and isophotal axis ratios.Comment: ApJ, in pres
Mass of Clusters in Simulations
We show that dark matter haloes, in n--body simulations, have a boundary
layer (BL) with precise features. In particular, it encloses all dynamically
stable mass while, outside it, dynamical stability is lost soon. Particles can
pass through such BL, which however acts as a confinement barrier for dynamical
properties. BL is set by evaluating kinetic and potential energies (T(r) and
W(r)) and calculating R=-2T/W. Then, on BL, R has a minimum which closely
approaches a maximum of w= -dlog W/dlog r. Such ``requirement'' is
consistent with virial equilibrium, but implies further regularities. We test
the presence of a BL around haloes in spatially flat CDM simulations, with or
without cosmological constant. We find that the mass M_c, enclosed within the
radius r_c, where the requirement is fulfilled, closely approaches the
mass M_{dyn}, evaluated from the velocities of all particles within r_c,
according to the virial theorem. Using r_c we can then determine an individual
density contrast Delta_c for each virialized halo, which can be compared with
the "virial" density contrast (Omega_m: matter
density parameter) obtained assuming a spherically symmetric and unperturbed
fluctuation growth. The spread in Delta_c is wide, and cannot be neglected when
global physical quantities related to the clusters are calculated, while the
average Delta_c is ~25 % smaller than the corresponding Delta_v; moreover if
is defined from the radius linked to Delta_v, we have a much worse
fit with particle mass then starting from {\it Rw} requirement.Comment: 4 pages, 5 figures, contribution to the XXXVIIth Rencontres de
Moriond, The Cosmological Model, Les Arc March 16-23 2002, to appear in the
proceeding
Walking Through the Rising : from Bolton Street Tech to the Four Courts and Back
THE MILITARY ACTION OF THE I ST BATTALION OF THE IRISH VOLUNTEERS IN NORTH INNER CITY DUBLIN IN 1916.
Introduction by Theo Dorgan.
52.p. ill. col. 21 cm
Evaluation of denoising strategies to address motion-correlated artifacts in resting-state functional magnetic resonance imaging data from the human connectome roject
Like all resting-state functional connectivity data, the data from the Human Connectome Project (HCP) are adversely affected by structured noise artifacts arising from head motion and physiological processes. Functional connectivity estimates (Pearson's correlation coefficients) were inflated for high-motion time points and for high-motion participants. This inflation occurred across the brain, suggesting the presence of globally distributed artifacts. The degree of inflation was further increased for connections between nearby regions compared with distant regions, suggesting the presence of distance-dependent spatially specific artifacts. We evaluated several denoising methods: censoring high-motion time points, motion regression, the FMRIB independent component analysis-based X-noiseifier (FIX), and mean grayordinate time series regression (MGTR; as a proxy for global signal regression). The results suggest that FIX denoising reduced both types of artifacts, but left substantial global artifacts behind. MGTR significantly reduced global artifacts, but left substantial spatially specific artifacts behind. Censoring high-motion time points resulted in a small reduction of distance-dependent and global artifacts, eliminating neither type. All denoising strategies left differences between high- and low-motion participants, but only MGTR substantially reduced those differences. Ultimately, functional connectivity estimates from HCP data showed spatially specific and globally distributed artifacts, and the most effective approach to address both types of motion-correlated artifacts was a combination of FIX and MGTR
Detection of Yersinia enterocolitica serotype O:9 in the faeces of cattle with false positive reactions in serological tests for brucellosis in Ireland
Intestinal infection by Yersinia enterocolitica serotype O:9 (YeO9) in cattle has been linked to false positive serological reactivity (FPSR) in diagnostic tests for brucellosis. Although eradicated in Ireland, brucellosis monitoring still identifies seropositive animals, usually one or two (termed singletons) per herd, which are classed as FPSR. To investigate a link between FPSR and YeO9, faeces and blood were collected from singleton FPSR cattle, and from companion animals, in eight selected herds with more than one FPSR animal, for YeO9 culture and Brucella serology. YeO9 was isolated from 76/474 (16%) FPSR singletons in 309 herds, but not from any of 621 animals in 122 control non-FPSR herds. In the FPSR herds 52/187 (27.8%) animals were culture positive, and 17% of the isolates were from seronegative animals. Seropositive animals were more likely to have a rising antibody titre when culture positive
Resilience of African migrants: An integrative review
© 2016 Taylor & Francis Group, LLC. African migrant women represent a rapidly growing cohort of new arrivals in many countries. Many of these women demonstrate strength and resilience throughout the stressful migration process. In this integrative review, we explore the literature on African migrants' resilience using an ecological framework. Nine peer-reviewed journal articles and six grey literature documents were reviewed. Key internal and external factors in achieving resilience were identified, discussed, and diagrammatically represented using Bronfenbrenner's Ecological Framework under micro-, meso-, exo-, and macro-levels. Our findings show that the capacity for resilience demonstrated during migration could have implications for policy and practice
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