438 research outputs found
Electric utility acid fuel cell stack technology advancement
The principal effort under this program was directed at the fuel cell stack technology required to accomplish the initial feasibility demonstrations of increased cell stack operating pressures and temperatures, increased cell active area, incorporation of the ribbed substrate cell configuration at the bove conditions, and the introduction of higher performance electrocatalysts. The program results were successful with the primary accomplishments being: (1) fabrication of 10 sq ft ribbed substrate, cell components including higher performing electrocatalysts; (2) assembly of a 10 sq ft, 30-cell short stack; and (3) initial test of this stack at 120 psia and 405 F. These accomplishments demonstrate the feasibility of fabricating and handling large area cells using materials and processes that are oriented to low cost manufacture. An additional accomplishment under the program was the testing of two 3.7 sq ft short stacks at 12 psia/405 F to 5400 and 4500 hours respectively. These tests demonstrate the durability of the components and the cell stack configuration to a nominal 5000 hours at the higher pressure and temperature condition planned for the next electric utility power plant
Constraining the dark energy equation of state with double source plane strong lenses
We investigate the possibility of constraining the dark energy equation of
state by measuring the ratio of Einstein radii in a strong gravitational lens
system with two source planes. This quantity is independent of the Hubble
parameter and directly measures the growth of angular diameter distances as a
function of redshift. We investigate the prospects for a single double source
plane system and for a forecast population of systems discovered by
re-observing a population of single source lenses already known from a
photometrically selected catalogue such as CASSOWARY or from a
spectroscopically selected catalogue such as SLACS. We find that constraints
comparable to current data-sets (15% uncertainty on the dark equation of state
at 68%CL) are possible with a handful of double source plane systems. We also
find that the method's degeneracy between Omega_M and w is almost orthogonal to
that of CMB and BAO measurements, making this method highly complimentary to
current probes.Comment: 13 Page
Innocent Frauds Meet Goodhart’s Law in Monetary Policy
This paper discusses recent UK monetary policies as instances of Galbraith’s ‘innocent frauds’, including the idea that money is a thing rather than a relationship, the fallacy of composition that what is possible for one bank is possible for all banks, and the belief that the money supply can be controlled by reserves management. The origins of the idea of QE, and its defense when it was applied in Britain, are analysed through this lens. An empirical analysis of the effect of reserves on lending is conducted; we do not find evidence that QE ‘worked’ either by a direct effect on money spending, or through an equity market effect. These findings are placed in a historical context in a comparison with earlier money control experiments in the UK
Optimal Stimulus Amplitude for Vestibular Stochastic Stimulation to Improve Sensorimotor Function
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface. This technique to improve detection of vestibular signals uses a stimulus delivery system that is wearable or portable and provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for SR training applications customized to each crewmember. Customizing stimulus intensity can maximize treatment effects. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds. We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. First we determined the percent time during stimulation periods for which perception of motion (activity above a pre-defined threshold) was reported using the joystick, and body sway (two standard deviation of the noise level in the baseline measurement) was detected by the sensors. The percentage time at each stimulation level for motion detection was normalized with respect to the largest value and a logistic regression curve fit was applied to these data. The threshold was defined at the 50% probability of motion detection. Comparison of threshold of motion detection obtained from joystick data versus body sway suggests that perceptual thresholds were significantly lower, and were not impacted by system noise. Further, in order to determine optimal stimulation amplitude to improve balance, two sets of experiments were carried out. In the first set of experiments, all subjects received the same level of stimuli and the intensity of optimal performance was projected back on subjects' vestibular threshold curve. In the second set of experiments, on different subjects, stimulation was administered from 20-400% of subjects' vestibular threshold obtained from joystick data. Preliminary results of our study show that, in general, using stimulation amplitudes at 40-60% of perceptual motion threshold improved balance performance significantly compared to control (no stimulation). The amplitude of vestibular stimulation that improved balance function was predominantly in the range of +/- 100 to +/- 400 micro A. We hypothesize that VSR stimulation will act synergistically with sensorimotor adaptability (SA) training to improve adaptability by increasing utilization of vestibular information and therefore will help us to optimize and personalize a SA countermeasure prescription. This combination will help to significantly reduce the number of days required to recover functional performance to preflight levels after long-duration spaceflight
The ecology of outdoor rape: The case of Stockholm, Sweden
The objective of this article is to report the results of an ecological study into the geography of rape in Stockholm, Sweden, using small area data. In order to test the importance of factors indicating opportunity, accessibility and anonymity to the understanding of the geography of rape, a two-stage modelling approach is implemented. First, the overall risk factors associated with the occurrence of rape are identified using a standard Poisson regression, then a local analysis using profile regression is performed. Findings from the whole-map analysis show that accessibility, opportunity and anonymity are all, to different degrees, important in explaining the overall geography of rape - examples of these risk factors are the presence of subway stations or whether a basomraÌŠde is close to the city centre. The local analysis reveals two groupings of high risk of rape areas associated with a variety of risk factors: city centre areas with a concentration of alcohol outlets, high residential population turnover and high counts of robbery; and poor suburban areas with schools and large female residential populations where subway stations are located and where people express a high fear of crime. The article concludes by reflecting upon the importance of these results for future research as well as indicating the implications of these results for policy
Strong Gravitational Lensing as a Probe of Gravity, Dark-Matter and Super-Massive Black Holes
Whereas considerable effort has been afforded in understanding the properties
of galaxies, a full physical picture, connecting their baryonic and dark-matter
content, super-massive black holes, and (metric) theories of gravity, is still
ill-defined. Strong gravitational lensing furnishes a powerful method to probe
gravity in the central regions of galaxies. It can (1) provide a unique
detection-channel of dark-matter substructure beyond the local galaxy group,
(2) constrain dark-matter physics, complementary to direct-detection
experiments, as well as metric theories of gravity, (3) probe central
super-massive black holes, and (4) provide crucial insight into galaxy
formation processes from the dark matter point of view, independently of the
nature and state of dark matter. To seriously address the above questions, a
considerable increase in the number of strong gravitational-lens systems is
required. In the timeframe 2010-2020, a staged approach with radio (e.g. EVLA,
e-MERLIN, LOFAR, SKA phase-I) and optical (e.g. LSST and JDEM) instruments can
provide 10^(2-4) new lenses, and up to 10^(4-6) new lens systems from
SKA/LSST/JDEM all-sky surveys around ~2020. Follow-up imaging of (radio) lenses
is necessary with moderate ground/space-based optical-IR telescopes and with
30-50m telescopes for spectroscopy (e.g. TMT, GMT, ELT). To answer these
fundamental questions through strong gravitational lensing, a strong investment
in large radio and optical-IR facilities is therefore critical in the coming
decade. In particular, only large-scale radio lens surveys (e.g. with SKA)
provide the large numbers of high-resolution and high-fidelity images of lenses
needed for SMBH and flux-ratio anomaly studies.Comment: White paper submitted to the 2010 Astronomy & Astrophysics Decadal
Surve
Visual Acuity and Associated Factors. The Central India Eye and Medical Study
Visual acuity is a major parameter for quality of vision and quality of life. Information on visual acuity and its associated factors in rural societies almost untouched by any industrialization is mostly non-available. It was, therefore, the purpose of our study to determine the distribution of visual acuity and its associated factors in a rural population not marked influenced by modern lifestyle. The population-based Central India Eye and Medical Study included 4711 subjects (aged 30+ years), who underwent a detailed ophthalmologic examination including visual acuity measurement. Visual acuity measurements were available for 4706 subjects with a mean age of 49.5±13.4 years (range: 30–100 years). BCVA decreased significantly (P<0.001) from the moderately hyperopic group (0.08±0.15 logMAR) to the emmetropic group (0.16±0.52 logMAR), the moderately myopic group (0.28±0.33 logMAR), the highly hyperopic group (0.66±0.62 logMAR) and finally the highly myopic group (1.32±0.92 logMAR). In multivariate analysis, BCVA was significantly associated with the systemic parameters of lower age (P<0.001), higher level of education (P<0.001), higher body stature (P<0.001) and higher body mass index (P<0.001), and with the ophthalmic parameters of more hyperopic refractive error (spherical equivalent) (P<0.001), shorter axial length (P<0.001), lower degree of nuclear cataract (P<0.001), and lower intraocular pressure (P = 0.006). The results suggest that in the rural population of Central India, major determinants of visual acuity were socioeconomic background, body stature and body mass index, age, refractive error, cataract and intraocular pressure
Estimation of an Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). The goal of this project was to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection
Determine Optimal Stimulus Amplitude for Using Vestibular Stochastic Stimulation to Improve Balance Function
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface [1]. This technique to improve detection of vestibular signals uses a stimulus delivery system that provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for sensorimotor adaptability (SA) training applications customized to each crewmember. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds [2]. We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s long sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. Comparison of threshold of motion detection obtained from joystick data versus body sway suggests that perceptual thresholds were significantly lower. In the balance task, subjects stood on an unstable surface and had to maintain balance, and the stimulation was administered from 20-400% of subjects' vestibular threshold. Optimal stimulation amplitude was determined at which the balance performance was best compared to control (no stimulation). Preliminary results show that, in general, using stimulation amplitudes at 40-60% of perceptual motion threshold significantly improved the balance performance. We hypothesize that VSR stimulation will act synergistically with SA training to improve adaptability by increasing utilization of vestibular information and therefore will help us to optimize and personalize a SA countermeasure prescription. This combination may help to significantly reduce the number of days required to recover functional performance to preflight levels after long-duration spaceflight
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