Control of long-range correlations in turbulence

The character of turbulence depends on where it develops. Turbulence near boundaries, for instance, is different than in a free stream. To elucidate the differences between flows, it is instructive to vary the structure of turbulence systematically, but there are few ways of stirring turbulence that make this possible. In other words, an experiment typically examines either a boundary layer or a free stream, say, and the structure of the turbulence is fixed by the geometry of the experiment. We introduce a new active grid with many more degrees of freedom than previous active grids. The additional degrees of freedom make it possible to control various properties of the turbulence. We show how long-range correlations in the turbulent velocity fluctuations can be shaped by changing the way the active grid moves. Specifically, we show how not only the correlation length but also the detailed shape of the correlation function depends on the correlations imposed in the motions of the grid. Until now, large-scale structure had not been adjustable in experiments. This new capability makes possible new systematic investigations into turbulence dissipation and dispersion, for example, and perhaps in flows that mimic features of boundary layers, free streams, and flows of intermediate character.Comment: This paper has been accepted to Experiments in Fluids. 25 pages, 10 figure

DEVELOPMENT OF PROTEIN CAPSULAR MATRIX VACCINE (PCMV) TECHNOLOGY

Matrivax R&D Corp. is a start-up biotechnology company with R&D operations located in Boston, USA and a vaccine pilot facility in Haikou, China. We are developing a proprietary vaccine process that entraps polysaccharides in a cross-linked protein ‘carrier’ or matrix, termed Protein Capsular Matrix Vaccine (PCMV), as an alternative to conjugate vaccine technology. Despite highly efficacious pneumococcal vaccines such as Prevnar®, S. pneumoniae causes \u3e 1 million deaths worldwide annually. Likewise, typhoid fever afflicts ~16 million people, resulting in 600,000 deaths despite effective vaccines such as Typhim Vi® and Ty21a. The premise is that inexpensive,efficacious polysaccharide vaccines that elicit TH-cell ‘memory’ will actively displace their unconjugated and conjugated vaccine counterparts. Towards this end, Matrivax is actively research and developing pneumococcal, enteric fever, and meningococcal PCMV candidates. In preliminary studies, a pneumococcal capsular polysaccharide (PPS) 14 ‘whole reaction’ PCMV employing ‘unoptimized chemistry’ elicited an anti-PPS14 reciprocal IgG antibody titer of ~7,000. Functional antibodies were elicited as evidenced by anti-sera facilitated opsonization and passively transferred antibodies conferring protection against lethal pneumococcal challenge. Recently Matrivax devised ‘optimized’ PCMV chemical reaction conditions improving polysaccharide incorporation into protein matrices as well as separated ‘whole reaction’ PCMV by size-exclusion chromatography yielding ‘size-fractionated’ PCMV particles. Size fractionated PPS14 PCMVs and Prevnar® were used to immunize mice in a three dose, bi-weekly regimen. Particle sized PCMV containing 0.12 and 0.03 ug PPS14 elicited anti-PPS14 reciprocal antibody GMT of 617,077 and 501,103,respectively, compared to Prevnar® (2 ug PPS14) which elicited a titer of 776,047. Thus, optimized PCMVs containing 1.5% or 6% the amount of PPS14 contained in Prevnar® elicited a comparable anti-PPS14 antibody response. Matrivax next evaluated PCMV’s applicability to Vi antigen. SDS-PAGE data demonstrated that Vi was captured in a DNI matrix and capture ELISA further indicated that Vi antigen was localized at the surface of PCMV particles. Size fractionated Vi-DNI PMCV was compared to Typhim Vi® following a three dose, bi-weekly vaccine regimen in a murine immunogenicity study. Ten (10) ug Typhim Vi elicited an anti-Vi reciprocal antibody GMT of 200 whereas size-fractionated PCMVs containing ~2 ug Vi elicited an anti-Vi antibody GMT of \u3e600. A Vi PCMV Phase 1 clinical trial is scheduled for 2Q11

An extension of Thwaites method for turbulent boundary layers

Thwaites (1949) developed an approximate method for determining the evolution of laminar boundary layers. The approximation follows from an assumption that the growth of a laminar boundary layer in the presence of pressure gradients could be parameterized solely as a function of a flow parameter, $m = \theta^2/\nu \frac{dU_e}{ds}$, thus reducing the von Karman momentum integral to a first-order ordinary differential equation. This method is useful for the analysis of laminar flows, and in computational potential flow solvers to account for the viscous effects. However, for turbulent flows, a similar approximation for turbulent boundary layers subjected to pressure gradients does not yet exist. In this work, an approximate method for determining the momentum thickness of a two-dimensional, turbulent boundary layer is proposed. It is shown that the method provides good estimates of the momentum thickness, when compared to available high-fidelity simulation data, for multiple boundary layers including both favorable and adverse pressure gradient effects, up to the point of separation. In the limit of high Reynolds numbers, it is possible to derive a criterion for the onset of separation from the proposed model which is shown to be in agreement with prior empirical observations (Alber, \textit{$9^{th}$ Aerospace Sciences Meeting, 1971}). The sensitivity of the separation location with respect to upstream perturbations is also analyzed through this model for the NASA/Boeing speed bump and the transonic Bachalo-Johnson bumpComment: 21 pages, 13 figures. Under consideration for publication in J. Fluid Mec

Subtle and Overt Forms of Islamophobia: Microaggressions toward Muslim Americans

Previous research suggests that microaggressions, or subtle and covert manifestations of bias, are commonplace in the life experience of people of color, women, and sexual minorities. However, there is a dearth of research focusing on microaggressions toward people from religious minority groups. Using a qualitative approach and directed content analysis with Muslim American participants (N=10), six themes emerged: 1) Endorsing Religious Stereotypes of Muslims as Terrorists, 2) Pathology of the Muslim Religion, 3) Assumption of Religious Homogeneity, 4) Exoticization, 5) Islamophobic and Mocking Language, and 6) Alien in Own Land. Implications for Muslim mental health are discussed

How a turn to critical race theory can contribute to our understanding of 'race', racism and anti-racism in sport

As long as racism has been associated with sport there have been consistent, if not coordinated or coherent, struggles to confront its various forms. Critical race theory (CRT) is a framework established to challenge these racialized inequalities and racism in society and has some utility for anti-racism in sport. CRT's focus on social justice and transformation are two areas of convergence between critical race theorists and anti-racists. Of the many nuanced and pernicious forms of racism, one of the most obvious and commonly reported forms of racism in sport, racial abuse, has been described as a kind of dehumanizing process by Gardiner (2003), as those who are its target are simultaneously (re)constructed and objectified according to everyday myth and fantasy. However, this is one of the many forms of everyday racist experiences. Various forms of racism can be experienced in boardrooms, on television, in print, in the stands, on the sidelines and on the pitch. Many times racism is trivialized and put down as part of the game (Long et al., 2000), yet its impact is rarely the source of further exploration. This article will explore the conceptualization of 'race' and racism for a more effective anti-racism. Critical race theory will also be used to explore the ideas that underpin considerations of the severity of racist behaviour and the implications for anti-racism. © The Author(s) 2010

Loss of Social Behaviours in Populations of Pseudomonas aeruginosa Infecting Lungs of Patients with Cystic Fibrosis

Pseudomonas aeruginosa, is an opportunistic, bacterial pathogen causing persistent and frequently fatal infections of the lung in patients with cystic fibrosis. Isolates from chronic infections differ from laboratory and environmental strains in a range of traits and this is widely interpreted as the result of adaptation to the lung environment. Typically, chronic strains carry mutations in global regulation factors that could effect reduced expression of social traits, raising the possibility that competitive dynamics between cooperative and selfish, cheating strains could also drive changes in P. aeruginosa infections. We compared the expression of cooperative traits - biofilm formation, secretion of exo-products and quorum sensing (QS) - in P. aeruginosa isolates that were estimated to have spent different lengths of time in the lung based on clinical information. All three exo-products involved in nutrient acquisition were produced in significantly smaller quantities with increased duration of infection, and patterns across four QS signal molecules were consistent with accumulation over time of mutations in lasR, which are known to disrupt the ability of cells to respond to QS signal. Pyocyanin production, and the proportion of cells in biofilm relative to motile, free-living cells in liquid culture, did not change. Overall, our results confirm that the loss of social behaviour is a consistent trend with time spent in the lung and suggest that social dynamics are potentially relevant to understanding the behaviour of P. aeruginosa in lung infections

Deconvolution of Images from BLAST 2005: Insight into the K3-50 and IC 5146 Star-Forming Regions

We present an implementation of the iterative flux-conserving Lucy-Richardson (L-R) deconvolution method of image restoration for maps produced by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). We have analyzed its performance and convergence extensively through simulations and cross-correlations of the deconvolved images with available highresolution maps. We present new science results from two BLAST surveys, in the Galactic regions K3-50 and IC 5146, further demonstrating the benefits of performing this deconvolution. We have resolved three clumps within a radius of 4.'5 inside the star-forming molecular cloud containing K3-50. Combining the well-resolved dust emission map with available multi-wavelength data, we have constrained the Spectral Energy Distributions (SEDs) of five clumps to obtain masses (M), bolometric luminosities (L), and dust temperatures (T). The L-M diagram has been used as a diagnostic tool to estimate the evolutionary stages of the clumps. There are close relationships between dust continuum emission and both 21-cm radio continuum and 12CO molecular line emission. The restored extended large scale structures in the Northern Streamer of IC 5146 have a strong spatial correlation with both SCUBA and high resolution extinction images. A dust temperature of 12 K has been obtained for the central filament. We report physical properties of ten compact sources, including six associated protostars, by fitting SEDs to multi-wavelength data. All of these compact sources are still quite cold (typical temperature below ~ 16 K) and are above the critical Bonner-Ebert mass. They have associated low-power Young Stellar Objects (YSOs). Further evidence for starless clumps has also been found in the IC 5146 region.Comment: 13 pages, 12 Figures, 3 Table

Cilia Proteins are Biomarkers of Altered Flow in the Vasculature

Cilia, microtubule-based organelles that project from the apical luminal surface of endothelial cells (ECs), are widely regarded as low-flow sensors. Previous reports suggest that upon high shear stress, cilia on the EC surface are lost, and more recent evidence suggests that deciliation—the physical removal of cilia from the cell surface—is a predominant mechanism for cilia loss in mammalian cells. Thus, we hypothesized that EC deciliation facilitated by changes in shear stress would manifest in increased abundance of cilia-related proteins in circulation. To test this hypothesis, we performed shear stress experiments that mimicked flow conditions from low to high shear stress in human primary cells and a zebrafish model system. In the primary cells, we showed that upon shear stress induction, indeed, ciliary fragments were observed in the effluent in vitro, and effluents contained ciliary proteins normally expressed in both endothelial and epithelial cells. In zebrafish, upon shear stress induction, fewer cilia-expressing ECs were observed. To test the translational relevance of these findings, we investigated our hypothesis using patient blood samples from sickle cell disease and found that plasma levels of ciliary proteins were elevated compared with healthy controls. Further, sickled red blood cells demonstrated high levels of ciliary protein (ARL13b) on their surface after adhesion to brain ECs. Brain ECs postinteraction with sickle RBCs showed high reactive oxygen species (ROS) levels. Attenuating ROS levels in brain ECs decreased cilia protein levels on RBCs and rescued ciliary protein levels in brain ECs. Collectively, these data suggest that cilia and ciliary proteins in circulation are detectable under various altered-flow conditions, which could serve as a surrogate biomarker of the damaged endothelium