Ocean waves provide a vast, uninterrupted resource of renewable energy collocated around large coastal population centers. Clean energy from ocean waves can contribute to the local electrical grid ...without the need for long-term electrical storage, yet due to the current high cost of energy extraction from ocean waves, there is no commercial ocean wave farm in operation. One of the wave energy converter (WEC) device classes that show the potential to enable economic energy generation from ocean waves is the class of wave terminators. This work investigates the Cycloidal Wave Energy Converter (CycWEC), which is a one-sided, lift-based wave terminator operating with coupled hydrofoils. The energy that the CycWEC extracted from ocean waves was estimated using a control volume analysis model of the 3D wave field in the presence of the CycWEC. The CycWEC was operated under feedback control to extract the maximum amount of energy possible from the incoming waves, and the interaction with different incoming regular, irregular, and short crested waves was examined.
The microPET R4 scanner is a dedicated positron emission tomograph (PET) for studies of rodents. A number of scanner parameters such as spatial resolution, sensitivity, scatter, and count rate ...performance were determined in this work, which showed that the microPET R4 is a suitable PET scanner for small animals like mice and rats. In the center of the field of view (FOV) a maximal sensitivity of 43.66 cps/kBq for a centered point source was calculated from a measurement with a germanium-68 line source within an energy widow of 250-750 keV. A spatial resolution of 1.85 mm full-width at half-maximum (FWHM) in the axial direction and 1.66 mm FWHM in the transaxial direction was measured in the center with a 1-mm-diameter sodium-22 point source. Within the inner 20 mm of the FOV the volumetric resolution is better than 15.6 micro l, corresponding to a linear resolution of less than 2.5 mm in all three dimensions. Images of a high-resolution phantom and from mice and rat studies illustrate the good performance of the scanner. A maximal noise equivalent count rate (NECR) was reached at 174 kcps for a mouse phantom and at 93 kcps for a rat phantom (energy window 250-750 keV). Scatter fractions were measured between 0.30 and 0.42 for an energy window of 250-750 keV and phantom diameters similar to mice and rats. A comparison with the microPET P4 model for primates illustrates the gain in sensitivity due to a smaller detector ring diameter but also the changes in NECR.
After military deployment, soldiers are at an increased risk of developing posttraumatic psychiatric disorders. The correlation of personal values with symptoms, however, has not yet been examined ...within a military context.
Schwartz's Portrait Values Questionnaire (PVQ), the Posttraumatic Stress Diagnostic Scale (PDS), and the 11-item version of the Resilience Scale (RS-11) were completed by 117 soldiers of the German Armed Forces who had recently been deployed to Afghanistan (n=40 undergoing initial psychiatric treatment, n=77 untreated).
Logistic regression showed that the value types of hedonism (−), power (−), tradition (+), and universalism (+) were significantly correlated with the probability and severity of PTSD and whether the participant was in treatment or not. The effects were partially mediated by the RS-11 scale values.
Value types seem to be associated with psychiatric symptoms in soldiers after deployment. These results could contribute to the further development of therapeutic approaches.
Performance Evaluation of the microPET®-FOCUS-F120 Laforest, R.; Longford, D.; Siegel, S. ...
IEEE transactions on nuclear science,
2007-Feb., 2007-02-00, 20070201, Letnik:
54, Številka:
1
Journal Article
Recenzirano
microPETreg-Focus-F120 is the latest model of dedicated small animal PET scanners from CTI-Concorde Microsystems LLC, (Knoxville, TN). This scanner, based on the geometry of the microPET-R4, takes ...advantage of several detector modifications to the coincidence processing electronics that improve the image resolution, sensitivity, and counting rate performance as compared to the predecessor models. This work evaluates the performance of the Focus-F120 system and shows its improvement over the earlier models. In particular, the spatial resolution is shown to improve from 2.32 to 1.69 mm at 5 mm radial distance and the peak absolute sensitivity increases from 4.1% to 7.1% compared to the microPET-R4. The counting rate capability, expressed in noise equivalent counting rate (NEC-1R), was shown to peak at over 800 kcps at 88 MBq for both systems using a mouse phantom. For this small phantom, the NECR counting rate is limited by the data transmission bandwidth between the scanner and the acquisition console. The rat-like phantom showed peak NEC-1R value at 300 kcps at 140 MBq. Evaluation of image quality and quantitation accuracy was also performed using specially designed phantoms and animal experiments
The low-speed flowfield for a generic unmanned combat air vehicle (UCAV) is investigated both experimentally and numerically. A wind tunnel experiment was conducted with the Boeing 1301 UCAV at a ...variety of angles of attack up to 70 degrees, both statically and with various frequencies of pitch oscillation (0.5, 1.0, and 2.0 Hz). In addition, pitching was performed about three longitudinal locations on the configuration (the nose, 35% MAC, and the tail). Solutions to the unsteady, laminar, compressible Navier–Stokes equations were obtained on an unstructured mesh to match results from the static and dynamic experiments. The computational results are compared with experimental results for both static and pitching cases. Details about the flowfield, including vortex formation and interaction, are shown and discussed, including the non-linear aerodynamic characteristics of the vehicle.
Military families who have a family member with a mental illness see themselves confronted with many demands. Stigmatization is one of these challenges. Stigmatization affects not only the individual ...who suffers from a mental illness but also other family members via stigma by association and vicarious stigma. Stigma by association occurs when mental illness stigma spills over to individuals associated with an individual with a mental illness. Vicarious stigma describes the suffering of family members when they note the impact of stigma on their relative with mental illness. As a societal phenomenon, stigma plays out in social interactions and might therefore influence the social networks of families. It is also associated with healthcare utilization.
Narrative interviews were conducted with 15 family members (partners, spouses, parents and children) of former soldiers of the German Armed Forces with a service-induced mental illness. The transcribed interview data were analyzed using a thematic analysis approach, in which codes were formed and emerging themes were systemized. Relationships between stigma, the families' reactions to it, its effects on their social relationships and its interference with their healthcare utilization were analyzed.
This study provides a detailed description of how relatives of former German soldiers with mental health problems experience stigma by association and vicarious stigma. Their perceptions are shown in a model that describes stigma-related attitudes, reactions to them and their effects on the social relationships of former soldiers' families. These families felt stigmatized because of the former soldiers' mental illness (mental illness stigma) and the military context in which it occurred (former soldier stigma). They reacted with nondisclosure, anger, acceptance and self-blame. Stigma was associated with smaller and weaker social networks that were characterized by social exclusion, self-segregation and conflicts with extended family, friends and colleagues. Stigma also affected the families' healthcare utilization.
Urgently needed anti-stigma campaigns, particularly in the civilian context, should address the stigmatization of both mental illness and the military participation of the families affected. They should consider the needs of both former soldiers with a mental illness and their families.
The effectiveness of a sensor configuration for feedback flow control on the wake of a circular cylinder is investigated in both direct numerical simulation as well as in a water tunnel experiment. ...The research program is aimed at suppressing the von Kármán vortex street in the wake of a cylinder at a Reynolds number of 100. The design of sensor number and placement was based on data from a laminar two-dimensional simulation of the Navier–Stokes equations for the unforced condition. A low-dimensional proper orthogonal decomposition (POD) was applied to the vorticity calculated from the flow field and sensor placement was based on the intensity of the resulting spatial eigenfunctions. The numerically generated data was comprised of 70 snapshots taken over three cycles from the steady state regime. A linear stochastic estimator (LSE) was employed to map the velocity data to the temporal coefficients of the reduced order model. The capability of the sensor configuration to provide accurate estimates of the four low-dimensional states was validated experimentally in a water tunnel at a Reynolds number of 108. For the experimental wake, a sample of 200 particle image velocimetry (PIV) measurements was used. Results show that for experimental data, the root mean square estimation error of the estimates of the first two modes was within 6% of the desired values and for the next two modes was within 20% of the desired values. This level of error is acceptable for a moderately robust controller.
The article is based on a series of surveys started in early December 2012 and ended in May 2018. The main goal of the study was a survey of the local resident breeding population of Yellow-Billed ...Kite (Milvus aegyptius). In total, 74 active nests and 2 inactive nests of Yellow-Billed Kite were found in surroundings of Cairo, Luxor, Lake Nasser and Abu Simbel.
Esta entrevista arroja luz sobre varios desarrollos actuales que amenazan el «núcleo» disciplinario de la educación. Partiendo de la «configuración» continental del campo, Gert Biesta y Stefan T. ...Siegel argumentan que existen formas de teoría consideradas distintivamente educativas. Basándose en esta premisa, discuten por qué resulta tan difícil definir las teorías de la educación (Erziehungswissenschaftliche Theorien) y por qué es, no obstante, una tarea provechosa. Al distinguir entre teorías de la educación (genuinamente) educativas en un sentido acotado y teorías de la educación (educativamente relevantes) en un sentido más amplio, Biesta y Siegel tratan de abordar el problema de la teoría de la educación y de estimular el discurso sobre la teorización de la educación. (Orig.).
This interview sheds light on current developments threatening the disciplinary 'heart' of education. Taking a starting point in the continental 'configuration' of the field, the authors argue that there are forms of theory considered distinctively educational. Based on this premise, they discuss why defining educational theories (Erziehungswissenschaftliche Theorien) is so challenging, and why it is never-theless a rewarding endeavour. By distinguishing between (genuinely) educational theories in a narrow sense and (educationally relevant) theories in a wider sense, the authors attempt to tackle the problem of educational theory and to stimulate the discourse on theorizing education. (Orig.)
An accurate, low noise estimate of photon attenuation in the subject is required for quantitative microPET studies of molecular tracer distributions in vivo. In this work, several transmission-based ...measurement techniques were compared, including coincidence mode with and without rod windowing, singles mode with two different energy sources ((68)Ge and (57)Co), and postinjection transmission scanning. In addition, the effectiveness of transmission segmentation and the propagation of transmission bias and noise into the emission images were examined. The (57)Co singles measurements provided the most accurate attenuation coefficients and superior signal-to-noise ratio, while (68)Ge singles measurements were degraded due to scattering from the object. Scatter correction of (68)Ge transmission data improved the accuracy for a 10 cm phantom but over-corrected for a mouse phantom. (57)Co scanning also resulted in low bias and noise in postinjection transmission scans for emission activities up to 20 MBq. Segmentation worked most reliably for transmission data acquired with (57)Co but the minor improvement in accuracy of attenuation coefficients and signal-to-noise may not justify its use, particularly for small subjects. We conclude that (57)Co singles transmission scanning is the most suitable method for measured attenuation correction on the microPET Focus 220 animal scanner.
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