Control of supersonic wind-tunnel noise by laminarization of nozzle-wall boundary layer

One of the principal design requirements for a quiet supersonic or hypersonic wind tunnel is to maintain laminar boundary layers on the nozzle walls and thereby reduce disturbance levels in the test flow. The conditions and apparent reasons for laminar boundary layers which have been observed during previous investigations on the walls of several nozzles for exit Mach numbers from 2 to 20 are reviewed. Based on these results, an analysis and an assessment of nozzle design requirements for laminar boundary layers including low Reynolds numbers, high acceleration, suction slots, wall temperature control, wall roughness, and area suction are presented

The experience of long stay in high and medium secure psychiatric hospitals in England: qualitative study of the patient perspective

Background: Some forensic patients in England remain in secure care for long, possibly unnecessarily prolonged, periods, raising significant ethical and resource issues. Research focused on the patients in secure care has examined quality of life and service provision but not the perspectives of patients experiencing long stays. This study explored how long stay patients experience secure care, what factors they felt influenced long stay, and its impact upon treatment engagement and motivation to progress. Methods: Embedded within a larger epidemiological study, we conducted semi-structured interviews with a purposive sample of forty long stay patients from two high and six medium secure hospitals. Long stay was defined as a 5 years stay in medium secure care or 10 years in high secure care, or 15 years in a combination of high and medium secure. Transcripts were subject to thematic analysis, and narrative analysis at individual case level to explore the relationship between emergent themes. Results: Four themes emerged illustrating participants’ attribution, outlook, approach, and readiness for change. A typology of four long stay stances was developed (dynamic acceptance, dynamic resistance, static acceptance, static resistance). These illustrate differences in the extent to which participants believed being in secure care helped them to get better, and actively work towards progression and leaving secure care. There were considerable differences in how patients adopting these stances attributed the reasons for their long stay, they viewed their future, and their motivation to progress. Negative perceptions arose from excessive restrictions, treatment repetition and changes in therapeutic relationships, leading some patients to exhibiting tokenistic engagement and low motivation to progress. Conclusions: Planning care for long stay patients in secure psychiatric settings should take account of the differing stances patient’s adopt towards engagement and progression. Service providers should be mindful of these stances and provide patients with individualised opportunities to progress through the secure care treatment pathway, avoiding treatment repetition and maintaining continuity in key professional relationships. Refocusing on quality of life may be appropriate for some long-term patients who are unwilling or unable to move on. For some long-term patients, purpose designed long stay setting may be appropriate

An automatic lightning detection and photographic system

Conventional 35-mm camera is activated by an electronic signal every time lightning strikes in general vicinity. Electronic circuit detects lightning by means of antenna which picks up atmospheric radio disturbances. Camera is equipped with fish-eye lense, automatic shutter advance, and small 24-hour clock to indicate time when exposures are made

The alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers mediate cell attachment to distinct sites on laminin.

This study was undertaken to determine the roles of individual alpha/beta 1 integrin heterodimers in promoting cellular interactions with the different attachment-promoting domains of laminin (LN). To do this, antibodies to the integrin beta 1 subunit or to specific integrin alpha subunits were tested for effects on cell attachment to LN, to elastase fragments E1-4 and E1, derived from the short arms and core of LN's cruciform structure, and to fragment E8 derived from the long arm of this structure. The human JAR choriocarcinoma cells used in this study attached to LN and to fragments E1 and E8. Attachment to E1-4 required a much higher substrate coating concentration, suggesting that it is a poor substrate for JAR cell attachment. The ability of cells to attach to different LN domains suggested the presence of more than one LN receptor. These multiple LN receptors were shown to be beta 1 integrin heterodimers because antibodies to the integrin beta 1 subunit inhibited attachment of JAR cells to LN and its three fragments. To identify the individual integrin alpha/beta 1 heterodimers that mediate interactions with these LN domains, mAbs specific for individual beta 1 heterodimers in human cells were used to study JAR cell interactions with LN and its fragments. An anti-alpha 6/beta 1-specific mAb, GoH3, virtually eliminated cell attachment to E8 and partially inhibited attachment to E1 and intact LN. Thus the major alpha 6/beta 1 attachment domain is present in fragment E8. An alpha 1/beta 1-specific mAb (S2G3) strongly inhibited cell attachment to collagen IV and partially inhibited JAR attachment to LN fragment E1. Thus, the alpha 1/beta 1 heterodimer is a dual receptor for collagen IV and LN, interacting with LN at a site in fragment E1. In combination, the anti-alpha 1- and anti-alpha 6-specific antibodies completely inhibited JAR cell attachment to LN and fragment E1. Thus, the alpha 1/beta 1 and alpha 6/beta 1 integrin heterodimers each function as LN receptors and act together to mediate the interactions of human JAR choriocarcinoma cells with LN

STRATEGIC INFORMATION SYSTEMS PLANNING IN U.S. COUNTY GOVERNMENTS: Will the Real SISP Model Please Stand Up?

This paper is the second in a series of studies examining strategic information systems planning (SISP) in U.S. governments based on information technology performance data and ratings generated for the Government Performance Project (2000 re states and 2001 re counties). The first study examined SISP at the state level (PPMR, June 2002). This study investigates SISP in county government using data from the 40 largest U.S. counties in terms of revenue within regions. Findings suggest that structural features of county government inhibit translation to counties of successful business models for strategic use of information systems, and they support the conclusion that models need to be adapted to meet the challenges of government planning. Examples of successful planning in some counties where the county CIO or the central county information technology office plan strategically within the limits of their authority may point a way toward a model for government. Further study is needed to develop a reliable U.S. government model for SISP

Effects of a modified leading edge on noise and boundary-layer transition in a rod-wall sound shield at Mach 5

A version of a rod wall sound shield was tested in the Mach 5 pilot quiet tunnel over a range of unit Reynolds numbers from 10 to 35 million per meter. The model was modified by inclining the leading edge plates to produce an initial 2 deg expansion to ascertain the sensitivity of boundary layer transition to leading edge disturbances. Rod surface pitot pressures, mean free stream pitot pressures, and static pressures on the rods and plenum walls were measured. Hot-wire measurements were also made in the model and nozzle free stream at a unit Reynolds number of 15 million per meter. The surface pitot pressures indicated that transition was much farther forward than for the previous tests due to the leading edge modification and minor fabrication flaws in the model. Early boundary layer transition on the rods was confirmed by hot-wire measurements which showed much higher noise levels in the free stream shield flow when compared with results from previous tests. Mean pitot pressure surveys within the shielded region inside the model indicated that there was an overexpansion and recompression that would limit the streamwise length of undisturbed flow to about 13 cm along the centerline

Bar-Halo Friction in Galaxies II: Metastability

It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at resonances. While some particles gain and others lose, friction arises when there is an excess of gainers over losers. This imbalance results from the generally decreasing numbers of particles with increasing angular momentum, and friction can therefore be avoided if there is no gradient in the density of particles across the major resonances. Here we show that anomalously weak friction can occur for this reason if the pattern speed of the bar fluctuates upwards. After such an event, the density of resonant halo particles has a local inflexion created by the earlier exchanges, and bar slowdown can be delayed for a long period; we describe this as a metastable state. We show that this behavior in purely collisionless N-body simulations is far more likely to occur in methods with adaptive resolution. We also show that the phenomenon could arise in nature, since bar-driven gas inflow could easily raise the bar pattern speed enough to reach the metastable state. Finally, we demonstrate that mild external, or internal, perturbations quickly restore the usual frictional drag, and it is unlikely therefore that a strong bar in a galaxy having a dense halo could rotate for a long period without friction.Comment: 13 pages, 11 figures, to appear in Ap