Wind tunnel quantification of dynamic stall on an S817 airfoil and its control using synthetic jet actuators

Wind tunnel experiments were performed to quantify the aerodynamic characteristics of the S817 airfoil in dynamic stall conditions, and the subsequent application of active flow control to modify the manner by which dynamic stall incepts. Both quasi‐2D and cantilevered finite span configurations were tested. Surface pressure, six‐component force‐torque sensor, and stereoscopic particle image velocimetry (SPIV) were used to quantify the baseline flow and the benefits of actuating synthetic jets (installed at x/c = 0.35, angled 45° into the flow, and at a momentum coefficient C_μ = 0.012). The airfoil was pitched at reduced frequencies of k_f = 0.025 and 0.05 and at shallow and deep stall. Vortex induced lift from dynamic stall was observed and was eliminated by the use of synthetic jets for nearly all conditions; pitching moment deviation was also observed to be significant, and was eliminated at shallow stall and significantly reduced during deep dynamic stall when the synthetic jets were actuated. Moreover, the activation of synthetic jets resulted in significant reduction in the hysteresis (area within the pitching up and pitching down load history) of the lift and pitching moment through all experimental conditions, as much as 41% and 85%, respectively. SPIV flow fields in shallow dynamic stall demonstrated that actuation of synthetic jets confined the separated region to the trailing edge, in both the instantaneous and time averaged sense. To further reduce the lift and pitching moment hysteresis at high angles of attack, a pulse modulation technique was used and showed a marked increase in synthetic jet performance compared with the continuously actuated case and achieved this result with approximately 65% less power consumption.     

Simplified laser to fibre coupling via optical fibre up-tapers

A new method for coupling single-mode fibre to laser diodes employing a spherical ruby lens and a single-mode optical fibre up-taper is demonstrated. High coupling efficiency and greatly reduced alignment sensitivities are attained     

The in vivo effect of recombinant human granulocyte-colony stimulating factor in neutropenic neonates with sepsis

The effects of recombinant granulocyte-colony stimulating factor (rhG-CSF) in neonatal neutropenia with presumed sepsis, which has a poor prognosis, were investigated. The study involved 14 neonates with presumed sepsis and neutropenia. Findings were compared with those from 24 historical controls. rhG-CSF (5 micrograms/ kg/day i.v. for 5 days) was administered immediately following diagnosis. Complete blood counts were obtained before and 24, 48, 72, 96 and 120 h after initiation of treatment. Neutrophil storage pool (NSP) was assessed (in 4 patients) before and after treatment. Statistical analysis was performed using one way analysis of variance. Treatment led to an increase in absolute neutrophil count (ANC) levels in 13/14 patients. At the end of treatment, the mean ANC was higher than that of controls (P = 0.007). There was a marked increase in the NSP of between 32% and 65% (P = 0.005). There were two clinical failures, one of whom was considered to have died from his underlying condition. There were no reports of clinical or haematological toxicity during treatment or follow up.     

Global-motion estimation in image sequences of 3-D scenes for coding applications

A technique for global-motion estimation and compensation in image sequences of 3-D scenes is described in this paper. Each frame is segmented into regions whose motion can be described by a single set of parameters and a set of motion parameters is estimated for each segment. This is done using an iterative block-based image segmentation combined with the estimation of the parameters describing the global motion of each segment. The segmentation is done using a Gibbs-Markov model-based iterative technique for finding a local optimum solution to a maximum a posteriori probability (MAP) segmentation problem. The initial condition for this process is obtained by applying a Hough transform to the motion vectors of each block in the frame obtained by block matching. In each iteration, given a segmentation, the motion parameters are estimated using the least-squares (LS) technique. To obtain the final segmentation and the more appropriate higher-order motion model for each segment, a final stage of splitting/merging of segments is needed. This step is performed on the basis of maximum-likelihood decisions combined with the determination of the higher-order model parameters by LS. The incorporation of the proposed global-motion estimation technique in an image-sequence coder was found to bring about a substantial reduction in bit-rate without degrading the perceived quality or the PSNR.     

Genes for chemokines MuMig and Crg-2 are induced in protozoan and viral infections in response to IFN-gamma with patterns of tissue expression that suggest nonredundant roles in vivo

MuMig and Crg-2 are IFN-inducible murine chemokines whose human homologues, HuMig and IP-10, respectively, share activity in vitro as T cell chemoattractants. We analyzed the expression of the genes Mumig, crg-2, and IFN-gamma during experimental infections with Plasmodium yoelii, Toxoplasma gondii, and vaccinia virus. Mumig, crg-2, and IFN-gamma were induced in multiple organs. During the acute phase of each infection as well as after i.p. injection of rIFN-gamma, levels of Mumig mRNA in the liver were as high or higher than levels in any of the other organs. In contrast, the organs showing the highest expression of crg-2 and IFN-gamma varied among the experimental models, with induction of these latter two genes colocalizing. Differences in relative levels of expression of Mumig and crg-2 in liver and spleen were not demonstrably due to expression of the genes in different cell types within these organs. We showed that both Mumig and crg-2 are induced in the liver in hepatocytes and in the spleen in CD11b+ cells. IFN-gamma was necessary for induction of Mumig during infections with T. gondii or vaccinia virus. In contrast, induction of crg-2 was not completely dependent on IFN-gamma. These data demonstrate that despite the overlap in activities within chemokine subsets, chemokine genes show differences in their patterns of expression and in their responses to inducers that suggest nonredundant roles in vivo. Moreover, the pattern of induction of crg-2 is consistent with Crg-2 acting primarily locally, while the pattern for Mumig induction suggests that MuMig may have a systemic role during infection.     

Degradation of distinct assembly forms of immunoglobulin M occurs in multiple sites in permeabilized B cells

Protein degradation is essential for quality control which retains and eliminates abnormal, unfolded, or partially assembled subunits of oligomeric proteins. The localization of this nonlysosomal pre-Golgi degradation to the endoplasmic reticulum (ER) has been mostly deduced from kinetic studies and carbohydrate analyses, while direct evidence for degradation within the ER has been provided by in vitro reconstitution of this process. In this article, we took advantage of the transport incompetence of permeabilized cells to directly demonstrate that the selective degradation of secretory IgM (sIgM) in B lymphocytes is transport-dependent. We show that, upon permeabilization of the plasma membrane with either streptolysin O or digitonin, sIgM is not degraded unless transport is allowed. Nevertheless, upon complete reduction of interchain disulfide bonds with thiols, the free mu heavy chains are degraded by a transport-independent quality control mechanism within the ER. This latter degradation is nonselective to the secretory heavy chain mus, and the membrane heavy chain mum, which is normally displayed on the surface of the B cell, is also eliminated. Moreover, the degradation of free mus is no longer restricted to B lymphocytes, and it takes place also in the ER of plasma cells which normally secrete polymers of sIgM. Conversely, when assembled with the light chain, the degradation is selective to sIgM, is restricted to B lymphocytes, and is a transport-dependent post-ER event.     

Low-reflectivity in-line variable attenuator utilizing opticalfiber tapers

A single-mode inline variable optical attenuator utilizing optical fiber tapers is discussed. Optical attenuation control is achieved through axial separation between two tapers with beveled endfaces aligned within a ceramic sleeve. Increased axial separation causes increased coupling loss between the two taper fundamental modes. Insertion loss of <0.5 dB, attenuation of >75 dB with continuous 0.05 dB resolution, and reflection return loss of better than 58 dB have been realized. Theoretical studies indicate low polarization and wavelength dependence, and inherent insertion loss of <0.1 dB. This design also exhibits simplicity of fabrication     

Control of aerosol dispersion and removal in a room using synthetic jet actuators

Synthetic jet actuators, a common actuator for flow control applications, were used to control particle dispersion in a closed chamber. The presented results demonstrate the application of this technique for controlling indoor air quality in confined spaces. This technique was demonstrated in a dedicated 0.23 m³ closed chamber that included a simulated ventilation system. The flow field in the room was determined using particle image velocimetry (PIV). Arrays of synthetic jets located on either side of an aerosol inlet (intake) provided the flow control. The effectiveness of the synthetic jet-based flow control was demonstrated for controlling airflow and aerosol dispersion and removal in the closed chamber. The use of such devices in smart buildings is expected to improve indoor air quality while minimizing the energy burden on heating, ventilating, and air conditioning (HVAC) systems.