Numerical study of large-eddy breakup and its effect on the drag characteristics of boundary layers

The break-up of a field of eddies by a flat-plate obstacle embedded in a boundary layer is studied using numerical solutions to the two-dimensional Navier-Stokes equations. The flow is taken to be incompressible and unsteady. The flow field is initiated from rest. A train of eddies of predetermined size and strength are swept into the computational domain upstream of the plate. The undisturbed velocity profile is given by the Blasius solution. The disturbance vorticity generated at the plate and wall, plus that introduced with the eddies, mix with the background vorticity and is transported throughout the entire flow. All quantities are scaled by the plate length, the unidsturbed free-stream velocity, and the fluid kinematic viscosity. The Reynolds number is 1000, the Blasius boundary layer thickness is 2.0, and the plate is positioned a distance of 1.0 above the wall. The computational domain is four units high and sixteen units long

Experimental Racetrack Shaped Jet Impingement on a Roughened Leading-Edge Wall With Film Holes,”

study are: (a) for a given jet Reynolds number, the racetrack crossover jets produce a higher impingement heat transfer coefficient than the circular jets, (b) the overall heat transfer performance of 0 o racetrack crossover jets is superior to that of 45 o racetrack crossover jets and (c) there is a heat transfer enhancement benefit in roughening the target surface. With the presence of showerhead holes, the enhancement is due to both the impingement heat transfer coefficient and the heat transfer area increase. NOMENCLATURE ABSTRACT Compatible with the external contour of the turbine airfoils at their leading edge, the leading-edge cooling cavities have a complex cross-sectional shape. To enhance the heat transfer coefficient on the leading-edge wall of these cavities, the cooling flow in some designs enters the leadingedge cavity from the adjacent cavity through a series of crossover holes on the partition wall between the two cavities. The crossover jets then impinge on the concave leading-edge wall and exit through the showerhead film holes, gill film holes on the pressure and suction sides, and, in some cases, form a crossflow in the leading-edge cavity and move toward the airfoil tip. The main objective of this investigation was to study the effects that racetrack crossover jets, in the presence of film holes on the target surface, have on the impingement heat transfer coefficient. Available data in open literature are mostly for impingement on a flat smooth surface with no representation of the film holes. This investigation covered new features in airfoil leading-edge cooling concept such as impingement with racetrack shaped holes on a roughened target surface with a row of holes representing the leading-edge showerhead film holes. Results of the circular crossover jets impinging on these leading-edge surface geometries with and without showerhead holes were reported by these authors previously. In this paper, however, the experimental results are presented for the impingement of racetrack-shaped crossover jets on a concave surface with showerhead film holes. The investigated target surface geometries were : (1) a smooth wall, (2) a wall roughened with big conical bumps, (3) a wall roughened with smaller conical bumps and (4) a wall roughened with tapered radial ribs. The tests were run for a range of flow arrangements and jet Reynolds numbers and the results were compared with those of round crossover jets. The major conclusions of thi

Shigella spp. surveillance in Indonesia: the emergence or reemergence of S. dysenteriae.

From June 1998 through November 1999, Shigella spp. were isolated in 5% of samples from 3,848 children and adults with severe diarrheal illness in hospitals throughout Indonesia. S. dysenteriae has reemerged in Bali, Kalimantan, and Batam and was detected in Jakarta after a hiatus of 15 years

Ethnicity Modifies the Relationships of Insulin Resistance, Inflammation, and Adiponectin With Obesity in a Multiethnic Asian Population

10.2337/dc10-2097Diabetes Care3451120-1126DICA

The Extracellular Domain of Myelin Oligodendrocyte Glycoprotein Elicits Atypical Experimental Autoimmune Encephalomyelitis in Rat and Species

Atypical models of experimental autoimmune encephalomyelitis (EAE) are advantageous in that the heterogeneity of clinical signs appears more reflective of those in multiple sclerosis (MS). Conversely, models of classical EAE feature stereotypic progression of an ascending flaccid paralysis that is not a characteristic of MS. The study of atypical EAE however has been limited due to the relative lack of suitable models that feature reliable disease incidence and severity, excepting mice deficient in gamma-interferon signaling pathways. In this study, atypical EAE was induced in Lewis rats, and a related approach was effective for induction of an unusual neurologic syndrome in a cynomolgus macaque. Lewis rats were immunized with the rat immunoglobulin variable (IgV)-related extracellular domain of myelin oligodendrocyte glycoprotein (IgV-MOG) in complete Freund’s adjuvant (CFA) followed by one or more injections of rat IgV-MOG in incomplete Freund’s adjuvant (IFA). The resulting disease was marked by torticollis, unilateral rigid paralysis, forelimb weakness, and high titers of anti-MOG antibody against conformational epitopes of MOG, as well as other signs of atypical EAE. A similar strategy elicited a distinct atypical form of EAE in a cynomolgus macaque. By day 36 in the monkey, titers of IgG against conformational epitopes of extracellular MOG were evident, and on day 201, the macaque had an abrupt onset of an unusual form of EAE that included a pronounced arousal-dependent, transient myotonia. The disease persisted for 6–7 weeks and was marked by a gradual, consistent improvement and an eventual full recovery without recurrence. These data indicate that one or more boosters of IgV-MOG in IFA represent a key variable for induction of atypical or unusual forms of EAE in rat and Macaca species. These studies also reveal a close correlation between humoral immunity against conformational epitopes of MOG, extended confluent demyelinating plaques in spinal cord and brainstem, and atypical disease induction

An Integrated Model of Multiple-Condition ChIP-Seq Data Reveals Predeterminants of Cdx2 Binding

Regulatory proteins can bind to different sets of genomic targets in various cell types or conditions. To reliably characterize such condition-specific regulatory binding we introduce MultiGPS, an integrated machine learning approach for the analysis of multiple related ChIP-seq experiments. MultiGPS is based on a generalized Expectation Maximization framework that shares information across multiple experiments for binding event discovery. We demonstrate that our framework enables the simultaneous modeling of sparse condition-specific binding changes, sequence dependence, and replicate-specific noise sources. MultiGPS encourages consistency in reported binding event locations across multiple-condition ChIP-seq datasets and provides accurate estimation of ChIP enrichment levels at each event. MultiGPS's multi-experiment modeling approach thus provides a reliable platform for detecting differential binding enrichment across experimental conditions. We demonstrate the advantages of MultiGPS with an analysis of Cdx2 binding in three distinct developmental contexts. By accurately characterizing condition-specific Cdx2 binding, MultiGPS enables novel insight into the mechanistic basis of Cdx2 site selectivity. Specifically, the condition-specific Cdx2 sites characterized by MultiGPS are highly associated with pre-existing genomic context, suggesting that such sites are pre-determined by cell-specific regulatory architecture. However, MultiGPS-defined condition-independent sites are not predicted by pre-existing regulatory signals, suggesting that Cdx2 can bind to a subset of locations regardless of genomic environment. A summary of this paper appears in the proceedings of the RECOMB 2014 conference, April 2–5.National Science Foundation (U.S.) (Graduate Research Fellowship under Grant 0645960)National Institutes of Health (U.S.) (grant P01 NS055923)Pennsylvania State University. Center for Eukaryotic Gene Regulatio