Measurement of space charge in the lower atmosphere

A double field mill is described which, when placed at a point abore the earth's surface, is automatically brought to the potential of that point and registers the potential gradient* Two such Instruments are employed to study space charge values In the first fire metres of the atmosphere. Comparison Is made between results obtained using the double mills and an Obolensky-type air filter, which lead to the conclusion that the latter instnuasnt gives incorrect readings in the presence of largp* small- ion concentrations. Space charge studies In fair weather conditions indicate the presence of a negative charge close to the ground of approximately -50µµC/m(^3), decreasing in the first two metres to aero and having an average value between one and three metres of +3µµC/m(^3). file average height to which this charge extends is shown to be proportional to the potential gradient, and has it's origin in ionization produced by radioactive substances in the earth, close to the surface. In disturbed conditions, heavy rain is found to generate a negative space charge of the order of -1000µµC/m(^3) arising from a splashing effect at the earth's surface. In snowfalls charges of +500µµC/m(^3) originate from the charge on the Individual snowflakes and a positive charge left in the air due to rubbing or shattering of the snow as it is falling*The fait weather results in the first metro show a good agreement with those of Norinder, but higher up show the usual positive charge found by Kahler, Daunderer, Scrase, Obolensky and Brown

Measurement of space charge if the lower atmosphere

A double field mill is described which, when, placed at a point above the earth's surface, is automatically brought to the potential of that point and registers the potential gradient. Two such instruments are employed to study space charge values in the first five metres, of the atmosphere •Comparison is made between results obtained using the double mills and an Obolensky-type air filter, which lead to the conclusion that the latter instrument gives incorrect readings in the presence of large small ion concentrations. Space charge studies in fair weather conditions, indicate the presence of a negative charge close to the ground of approximately -50µµC/m(^3)decreasing in the first two metres to aero and having an average value between one and three metres of +3 µµC/m(^3). The average height to which this charge extends is shown to be proportional to the potential gradient, and has it's origin in ionization produced by radioactive substances: in the earth, close to the surface. In disturbed conditions, heavy rain is found to generate a negative space charge of. the order of -1000 µµC/m(^3)arising from a splashing effect at the earth's surface. In snowfalls; charges of +500 µµC/m(^3) originate from the charge on the individual snowflakes and a positive charge left in the air due to rubbing or shattering of the snow as it. is falling. The fair weather results in the first metre show a good agreement with those of Norinder, but higher up show the usual positive charge found by Kahler, Daunderer, Scraae, Obolensky and Brown

Primary care-led commissioning and public involvement in the English National Health Service. Lessons from the past.

Background: Patient and Public involvement (PPI) in health care occupies a central place in Western democracies. In England, this theme has been continuously prominent since the introduction of market reforms in the early 1990s. The health care reforms implemented by the current Coalition Government are making primary care practitioners the main commissioners of health care services in the National Health Service, and a duty is placed on them to involve the public in commissioning decisions and strategies. Since implementation of PPI initiatives in primary care commissioning is not new, we asked how likely it is that the new reforms will make a difference. We scanned the main literature related to primary care-led commissioning and found little evidence of effective PPI thus far. We suggest that unless the scope and intended objectives of PPI are clarified and appropriate resources are devoted to it, PPI will continue to remain empty rhetoric and box ticking. Aim: To examine the effect of previous PPI initiatives on health care commissioning and draw lessons for future development. Method: We scanned the literature reporting on previous PPI initiatives in primary careled commissioning since the introduction of the internal market in 1991. In particular, we looked for specific contexts, methods and outcomes of such initiatives. Findings: 1. PPI in commissioning has been constantly encouraged by policy makers in England. 2. Research shows limited evidence of effective methods and outcomes so far. 3. Constant reconfi- guration of health care structures has had a negative impact on PPI. 4. The new structures look hardly better poised to bring about effective public and patient involvement

Shuttle electrical environment

Part of an AFGL payload flown on the STS-4 mission consisted of experiments to measure in-situ electric fields, electron densities, and vehicle charging. During this flight some 11 hours of data were acquired ranging from 5 minute snapshots up to continuous half-orbits. These experiments are described and results presented for such vehicle induced events as a main engine burn, thruster firings and water dumps in addition to undisturbed periods. The main characteristic of all the vehicle induced events is shown to be an enhancement in the low frequency noise (less than 2 kHz), in both the electrostatic and electron irregularity (delta N/N) spectra. The non-event results indicate that the electrostatic broadband emissions show a white noise characteristic in the low frequency range up to 2 kHz at an amplitude of 10 db above the shuttle design specification limit, falling below that limit above 10 kHz. The vehicle potential remained within the range of -3 to +1 volt throughout the flight which exhibits normal behavior for a satellite in a low equatorial orbit

Growth mindset and school burnout symptoms in young adolescents: the role of vagal activity as potential mediator

Experiencing school burnout symptoms can have negative consequences for learning. A growth mindset, the belief that human qualities such as intelligence are malleable, has previously been correlated with fewer school burnout symptoms in late adolescents. This might be because adolescents with a stronger growth mindset show more adaptive self-regulation strategies and thereby increasing resilience against academic setbacks. Here we confirmed in a sample of 426 Dutch young adolescents (11–14 years old; 48% female) that this relationship between growth mindset and school burnout symptoms holds after controlling for other potential predictors of school burnout symptoms such as academic achievement, school track, gender, and socio-economic status. Our second aim was to increase our understanding of the mechanism underlying the relation between mindset and school burnout, by measuring physiological resilience (vagal activity, a measure of parasympathetic activity, also known as heart rate variability or HRV) in a subsample (n = 50). We did not find any relation between vagal activity and growth mindset or school burnout symptoms, nor could we establish a mediating effect of vagal activity in their relation. In conclusion, we found evidence for a potential protective effect of a growth mindset on school burnout symptoms in young adolescents, but not for physiological resilience (vagal activity) as an underlying mechanism. The protective effect of growth mindset as confirmed in our younger sample can be leveraged in interventions to prevent increasing school burnout symptoms

Partial-thickness macular hole in vitreomacular traction syndrome: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Vitreomacular traction syndrome has recently been recognized as a distinct clinical condition. It may lead to many complications, such as cystoid macular edema, macular pucker formation, tractional macular detachment, and full-thickness macular hole formation.</p> <p>Case presentation</p> <p>We report a case of vitreomacular traction syndrome with eccentric traction at the macula and a partial-thickness macular hole in a 63-year-old Pakistani Punjabi man. The patient was evaluated using optical coherence tomography, and he underwent a successful pars plana vitrectomy. After the operation, his foveal contour regained normal configuration, and his visual acuity improved from 20/60 to 20/30.</p> <p>Conclusions</p> <p>Pars plana vitrectomy prevents the progression of a partial thickness macular hole in vitreomacular traction syndrome. The relief of traction by vitrectomy restores foveal anatomy and visual acuity in this condition.</p

Cost analysis of childhood glaucoma surgeries using the US Medicaire allowable costs

AIM: To analyze and calculate the relative cost of various childhood glaucoma surgical interventions per mm Hg intraocular pressure (IOP) reduction ($/mm Hg). METHODS: Representative index studies were reviewed to quantitate the reduction of mean IOP and glaucoma medications for each surgical intervention in childhood glaucoma. A US perspective was adopted, using Medicare allowable costs to calculate cost/mm Hg IOP reduction ($/mm Hg) at 1y postoperatively. RESULTS: At 1y postoperatively, the cost/mm Hg IOP reduction was $226/mm Hg for microcatheter-assisted circumferential trabeculotomy,$284/mm Hg for cyclophotocoagulation, $288/mm Hg for conventional ab-externo trabeculotomy,$338/mm Hg for Ahmed glaucoma valve, $350/mm Hg for Baerveldt glaucoma implant,$351/mm Hg for goniotomy, and $400/mm Hg for trabeculectomy. CONCLUSION: Microcatheter-assisted circumferential trabeculotomy is the most cost-efficient surgical method to lower IOP in childhood glaucoma, while trabeculectomy is the least cost-efficient surgical method

A Method of Drusen Measurement Based on the Geometry of Fundus Reflectance

BACKGROUND: The hallmarks of age-related macular degeneration, the leading cause of blindness in the developed world, are the subretinal deposits known as drusen. Drusen identification and measurement play a key role in clinical studies of this disease. Current manual methods of drusen measurement are laborious and subjective. Our purpose was to expedite clinical research with an accurate, reliable digital method. METHODS: An interactive semi-automated procedure was developed to level the macular background reflectance for the purpose of morphometric analysis of drusen. 12 color fundus photographs of patients with age-related macular degeneration and drusen were analyzed. After digitizing the photographs, the underlying background pattern in the green channel was leveled by an algorithm based on the elliptically concentric geometry of the reflectance in the normal macula: the gray scale values of all structures within defined elliptical boundaries were raised sequentially until a uniform background was obtained. Segmentation of drusen and area measurements in the central and middle subfields (1000 μm and 3000 μm diameters) were performed by uniform thresholds. Two observers using this interactive semi-automated software measured each image digitally. The mean digital measurements were compared to independent stereo fundus gradings by two expert graders (stereo Grader 1 estimated the drusen percentage in each of the 24 regions as falling into one of four standard broad ranges; stereo Grader 2 estimated drusen percentages in 1% to 5% intervals). RESULTS: The mean digital area measurements had a median standard deviation of 1.9%. The mean digital area measurements agreed with stereo Grader 1 in 22/24 cases. The 95% limits of agreement between the mean digital area measurements and the more precise stereo gradings of Grader 2 were -6.4 % to +6.8 % in the central subfield and -6.0 % to +4.5 % in the middle subfield. The mean absolute differences between the digital and stereo gradings 2 were 2.8 +/- 3.4% in the central subfield and 2.2 +/- 2.7% in the middle subfield. CONCLUSIONS: Semi-automated, supervised drusen measurements may be done reproducibly and accurately with adaptations of commercial software. This technique for macular image analysis has potential for use in clinical research

Bilateral macular hole formation secondary to sclopetaria caused by shockwaves transmitted by a posterior vector: case report

<p>Abstract</p> <p>Background</p> <p>Sclopetaria is a rare ophthalmic finding in trauma</p> <p>Case Presentation</p> <p>This is a report of a patient who developed macular holes from sclopetaria induced by indirect trauma. A 22-year-old male, suffered a gunshot wound that passed behind his eyes, resulting in bilateral macular hole formation</p> <p>Conclusion</p> <p>To our knowledge, this is the first reported case in which trauma posterior to the globes caused bilateral macular hole formation</p