Applications of satellite data relay to problems of field seismology

A seismic signal processor was developed and tested for use with the NOAA-GOES satellite data collection system. Performance tests on recorded, as well as real time, short period signals indicate that the event recognition technique used is nearly perfect in its rejection of cultural signals and that data can be acquired in many swarm situations with the use of solid state buffer memories. Detailed circuit diagrams are provided. The design of a complete field data collection platform is discussed and the employment of data collection platforms in seismic network is reviewed

MHz-Rate NO PLIF Imaging in a Mach 10 Hypersonic Wind Tunnel

NO PLIF imaging at repetition rates as high as 1 MHz is demonstrated in the NASA Langley 31 inch Mach 10 hypersonic wind tunnel. Approximately two hundred time correlated image sequences, of between ten and twenty individual frames, were obtained over eight days of wind tunnel testing spanning two entries in March and September of 2009. The majority of the image sequences were obtained from the boundary layer of a 20 flat plate model, in which transition was induced using a variety of cylindrical and triangular shaped protuberances. The high speed image sequences captured a variety of laminar and transitional flow phenomena, ranging from mostly laminar flow, typically at lower Reynolds number and/or in the near wall region of the model, to highly transitional flow in which the temporal evolution and progression of characteristic streak instabilities and/or corkscrew-shaped vortices could be clearly identified. A series of image sequences were also obtained from a 20 compression ramp at a 10 angle of attack in which the temporal dynamics of the characteristic separated flow was captured in a time correlated manner

Thinking strategically about assessment

Drawing upon the literature on strategy formulation in organisations, this paper argues for a focus on strategy as process. It relates this to the need to think strategically about assessment, a need engendered by resource pressures, developments in learning and the demands of external stakeholders. It is argued that in practice assessment strategies are often formed at the level of practice, but that this produces contradiction and confusion at higher levels. Such tensions cannot be managed away, but they can be reflected on and mitigated. The paper suggests a framework for the construction of assessment strategies at different levels of an institution. However, the main conclusion is that the process of constructing such strategies should be an opportunity for learning and reflection, rather than one of compliance

Stereoscopic Planar Laser-Induced Fluorescence Imaging at 500 kHz

A new measurement technique for obtaining time- and spatially-resolved image sequences in hypersonic flows is developed. Nitric-oxide planar laser-induced fluorescence (NO PLIF) has previously been used to investigate transition from laminar to turbulent flow in hypersonic boundary layers using both planar and volumetric imaging capabilities. Low flow rates of NO were typically seeded into the flow, minimally perturbing the flow. The volumetric imaging was performed at a measurement rate of 10 Hz using a thick planar laser sheet that excited NO fluorescence. The fluorescence was captured by a pair of cameras having slightly different views of the flow. Subsequent stereoscopic reconstruction of these images allowed the three-dimensional flow structures to be viewed. In the current paper, this approach has been extended to 50,000 times higher repetition rates. A laser operating at 500 kHz excites the seeded NO molecules, and a camera, synchronized with the laser and fitted with a beam-splitting assembly, acquires two separate images of the flow. The resulting stereoscopic images provide three-dimensional flow visualizations at 500 kHz for the first time. The 200 ns exposure time in each frame is fast enough to freeze the flow while the 500 kHz repetition rate is fast enough to time-resolve changes in the flow being studied. This method is applied to visualize the evolving hypersonic flow structures that propagate downstream of a discrete protuberance attached to a flat plate. The technique was demonstrated in the NASA Langley Research Center s 31-Inch Mach 10 Air Tunnel facility. Different tunnel Reynolds number conditions, NO flow rates and two different cylindrical protuberance heights were investigated. The location of the onset of flow unsteadiness, an indicator of transition, was observed to move downstream during the tunnel runs, coinciding with an increase in the model temperature

Resolving the Composite Fe K-alpha Emission Line in the Galactic Black Hole Cygnus X-1 with Chandra

We observed the Galactic black hole Cygnus X-1 with the Chandra High Energy Transmission Grating Spectrometer for 30 kiloseconds on 4 January, 2001. The source was in an intermediate state, with a flux that was approximately twice that commonly observed in its persistent low/hard state. Our best-fit model for the X-ray spectrum includes narrow Gaussian emission line (E = 6.415 +/- 0.007 keV, FWHM = 80 (+28, -19) eV, W = 16 (+3, -2) eV) and broad line (E = 5.82 (+0.06, -0.07) keV, FWHM = 1.9 (+0.5, -0.3) keV, W = 140 (+70, -40) eV) components, and a smeared edge at 7.3 +/- 0.2 keV (tau ~ 1.0). The broad line profile is not as strongly skewed as those observed in some Seyfert galaxies. We interpret these features in terms of an accretion disk with irradiation of the inner disk producing a broad Fe K-alpha emission line and edge, and irradiation of the outer disk producing a narrow Fe K-alpha emission line. The broad line is likely shaped predominantly by Doppler shifts and gravitational effects, and to a lesser degree by Compton scattering due to reflection. We discuss the underlying continuum X-ray spectrum and these line features in the context of diagnosing the accretion flow geometry in Cygnus X-1 and other Galactic black holes.Comment: Accepted for publication in Ap

High-Speed PLIF Imaging of Hypersonic Transition over Discrete Cylindrical Roughness

In two separate test entries, advanced laser-based instrumentation has been developed and applied to visualize the hypersonic flow over cylindrical protrusions on a flat plate. Upstream of these trips, trace quantities of nitric oxide (NO) were seeded into the boundary layer. The protuberances were sized to force laminar-to-turbulent boundary layer transition. In the first test, a 10-Hz nitric oxide planar laser-induced fluorescence (NO PLIF) flow visualization system was used to provide wide-field-of-view, high-resolution images of the flowfield. The images had sub-microsecond time resolution. However these images, obtained with a time separation of 0.1 sec, were uncorrelated with each other. Fluorescent oil-flow visualizations were also obtained during this test. In the second experiment, a laser and camera system capable of acquiring NO PLIF measurements at 1 million frames per second (1 MHz) was used. This system had lower spatial resolution, and a smaller field of view, but the images were time correlated so that the development of the flow structures could be observed in time

What’s Sex (Composition) Got to Do with It? The Importance of Sex Composition of Gangs for Female and Male Members’ Offending and Victimization

Sex composition of groups has been theorized in organizational sociology and found in prior work to structure female and male members’ behaviors and experiences. Peer group and gang literature similarly finds that the sex gap in offending varies across groups of differing sex ratios. Drawing on this and other research linking gang membership, offending, and victimization, we examine whether sex composition of gangs is linked to sex differences in offending in this sample, further assess whether sex composition similarly structures females’ and males’ victimization experiences, and if so, why. Self-report data from gang members in a multi-site, longitudinal study of 3,820 youths are employed. Results support previous findings about variations in member delinquency by both sex and sex composition of the gang and also indicate parallel variations in members’ victimization. These results are further considered within the context of facilitating effects such as gender dynamics, gang characteristics, and normative orientation

Women, men and coronary heart disease: a review of the qualitative literature

Aim. This paper presents a review of the qualitative literature which examines the experiences of patients with coronary heart disease. The paper also assesses whether the experiences of both female and male patients are reflected in the literature and summarizes key themes. Background. Understanding patients' experiences of their illness is important for coronary heart disease prevention and education. Qualitative methods are particularly suited to eliciting patients' detailed understandings and perceptions of illness. As much previous research has been 'gender neutral', this review pays particular attention to gender. Methods. Published papers from 60 qualitative studies were identified for the review through searches in MEDLINE, EMBASE, CINAHL, PREMEDLINE, PsychINFO, Social Sciences Citation Index and Web of Science using keywords related to coronary heart disease. Findings. Early qualitative studies of patients with coronary heart disease were conducted almost exclusively with men, and tended to generalize from 'male' experience to 'human' experience. By the late 1990s this pattern had changed, with the majority of studies including women and many being conducted with solely female samples. However, many studies that include both male and female coronary heart disease patients still do not have a specific gender focus. Key themes in the literature include interpreting symptoms and seeking help, belief about coronary 'candidates' and relationships with health professionals. The influence of social roles is important: many female patients have difficulties reconciling family responsibilities and medical advice, while male patients worry about being absent from work. Conclusions. There is a need for studies that compare the experiences of men and women. There is also an urgent need for work that takes masculinity and gender roles into account when exploring the experiences of men with coronary heart disease

Characterization of porous low-k films using variable angle spectroscopic ellipsometry

doi:10.1063/1.2189018Variable angle spectroscopic ellipsometry (VASE™) is used as a tool to characterize properties such as optical constant, thickness, refractive index depth profile, and pore volume fraction of single and bilayer porous low-k films. The porous films were prepared using sacrificial pore generator (porogen) approach. Two sets of porous films with open- and closed-pore geometries were measured. Three models were used for data analysis: Cauchy, Bruggeman effective medium approximation (BEMA), and graded layer. Cauchy, a well-known model for transparent films, was used to obtain thickness and optical constant, whereas BEMA was utilized to calculate the pore volume fraction from the ellipsometric data. The Cauchy or BEMA models were then modified as graded layers, resulting in a better fit and a better understanding of the porous film. The depth profile of the porous film implied a more porous layer at the substrate-film interface. We found 3%-4% more porosity at the interface compared with the bulk for both films. This work shows that VASE™, a nondestructive measurement tool, can be used to characterize single- and multigraded layer porous films quickly and effectively.The authors would like to acknowledge the financial support of Semiconductor Research Corporation (SRC)