2,562 research outputs found
Portable propellant cutting assembly, and method of cutting propellant with assembly
A propellant cutting assembly and method of using the assembly to cut samples of solid propellant in a repeatable and consistent manner is disclosed. The cutting assembly utilizes two parallel extension beams which are shorter than the diameter of a central bore of an annular solid propellant grain and can be loaded into the central bore. The assembly is equipped with retaining heads at its respective ends and an adjustment mechanism to position and wedge the assembly within the central bore. One end of the assembly is equipped with a cutting blade apparatus which can be extended beyond the end of the extension beams to cut into the solid propellant
Critical reappraisal of Balangero chrysotile and mesothelioma risk
BackgroundBalangero, 40 km northwest of Torino in the Piedmonte Region, was home to the largest and most active chrysotile mine in Europe operating from 1916 - 1990 and employed over 300 men at any one time. The chrysotile was thought to be pure. Despite this some claim it has been responsible for causing numerous mesotheliomas. This report refutes this claim on the grounds that it is not pure but potentially contaminated by tremolite asbestos. In addition there are numerous alternate sources of naturally occurring and commercially available amphibole asbestos in the region.MethodsGeological studies illustrate the presence of naturally occurring tremolite and various analyses have shown naturally occurring and commercially used amphibole its presence in animal and human tissue. The diagnostic criteria used to study pleural disease in the Balangero cohort were examined on a case by case basis.ResultsSeveral authors have searched available registries for post-mortem information and listed possible mesothelioma cases. Cross matching these searches has been attempted and the strength of their diagnoses examined.ConclusionThere is good evidence that crocidolite, amosite and tremolite are responsible for the alleged mesothelioma cases at Balangero. Myriad sources of naturally occurring and commercial amphibole asbestos exist in the region to account for the alleged cases. Regrettably, necessary information is incomplete and insufficient for the cohort which calls the diagnostic accuracy of the cases into question. The problem is further compounded by confusion surrounding job titles and raises the question if any of cases actually ever occurred in ‘miners’ per se
Rossby wave dynamics of the North Pacific extra-tropical response to El Niño: importance of the basic state in coupled GCMs
The extra-tropical response to El Nino in a "low" horizontal resolution coupled climate model, typical of the Intergovernmental Panel on Climate Change fourth assessment report simulations, is shown to have serious systematic errors. A high resolution configuration of the same model has a much improved response that is similar to observations. The errors in the low resolution model are traced to an incorrect representation of the atmospheric teleconnection mechanism that controls the extra-tropical sea surface temperatures (SSTs) during El Nino. This is due to an unrealistic atmospheric mean state, which changes the propagation characteristics of Rossby waves. These erroneous upper tropospheric circulation anomalies then induce erroneous surface circulation features over the North Pacific. The associated surface wind speed and direction errors create erroneous surface flux and upwelling anomalies which finally lead to the incorrect extra-tropical SST response to El Nino in the low resolution model. This highlights the sensitivity of the climate response to a single link in a chain of complex climatic processes. The correct representation of these processes in the high resolution model indicates the importance of horizontal resolution in resolving such processes
The effect of a sports chiropractic manual therapy intervention on the prevention of back pain, hamstring and lower limb injuries in semi-elite Australian Rules footballers: a randomized controlled trial
<p>Abstract</p> <p>Background</p> <p>Hamstring injuries are the most common injury in Australian Rules football. It was the aims to investigate whether a sports chiropractic manual therapy intervention protocol provided in addition to the current best practice management could prevent the occurrence of and weeks missed due to hamstring and other lower-limb injuries at the semi-elite level of Australian football.</p> <p>Methods</p> <p>Sixty male subjects were assessed for eligibility with 59 meeting entry requirements and randomly allocated to an intervention (n = 29) or control group (n = 30), being matched for age and hamstring injury history. Twenty-eight intervention and 29 control group participants completed the trial. Both groups received the current best practice medical and sports science management, which acted as the control. Additionally, the intervention group received a sports chiropractic intervention. Treatment for the intervention group was individually determined and could involve manipulation/mobilization and/or soft tissue therapies to the spine and extremity. Minimum scheduling was: 1 treatment per week for 6 weeks, 1 treatment per fortnight for 3 months, 1 treatment per month for the remainder of the season (3 months). The main outcome measure was an injury surveillance with a missed match injury definition.</p> <p>Results</p> <p>After 24 matches there was no statistical significant difference between the groups for the incidence of hamstring injury (OR:0.116, 95% CI:0.013-1.019, p = 0.051) and primary non-contact knee injury (OR:0.116, 95% CI:0.013-1.019, p = 0.051). The difference for primary lower-limb muscle strains was significant (OR:0.097, 95%CI:0.011-0.839, p = 0.025). There was no significant difference for weeks missed due to hamstring injury (4 v14, χ2:1.12, p = 0.29) and lower-limb muscle strains (4 v 21, χ2:2.66, p = 0.10). A significant difference in weeks missed due to non-contact knee injury was noted (1 v 24, χ2:6.70, p = 0.01).</p> <p>Conclusions</p> <p>This study demonstrated a trend towards lower limb injury prevention with a significant reduction in primary lower limb muscle strains and weeks missed due to non-contact knee injuries through the addition of a sports chiropractic intervention to the current best practice management.</p> <p>Trial registration</p> <p>The study was registered with the Australian and New Zealand Clinical Trials Registry (ACTRN12608000533392).</p
Move of a large but delicate apparatus on a trailer with air-ride suspension
When valuable delicate goods are shipped by truck, attention must be paid to
vibrations that may cause damage. We present a case study of moving an
extremely delicate 6230-kg superconducting magnet, immersed in liquid nitrogen,
from Livermore, CA to Seattle, WA showing the steps of fatigue analysis of the
load, a test move, and acceleration monitoring of the final move to ensure a
successful damage-free transport
Volatilization-devolatilization reactions
Experiments that explore chemical and physical aspects of volatilization reactions that require the microgravity and low pressure in or near the projected Space Station are proposed
Acoustically driven storage of light in a quantum well
The strong piezoelectric fields accompanying a surface acoustic wave on a
semiconductor quantum well structure are employed to dissociate optically
generated excitons and efficiently trap the created electron hole pairs in the
moving lateral potential superlattice of the sound wave. The resulting spatial
separation of the photogenerated ambipolar charges leads to an increase of the
radiative lifetime by orders of magnitude as compared to the unperturbed
excitons. External and deliberate screening of the lateral piezoelectric fields
triggers radiative recombination after very long storage times at a remote
location on the sample.Comment: 4 PostScript figures included, Physical Review Letters, in pres
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The role of temperature in the variability and extremes of electricity and gas demand in Great Britain
The daily relationship of electricity and gas demand with temperature in Great Britain is analysed from 1975 to 2013 and 1996 to 2013 respectively. The annual mean and annual cycle amplitude of electricity demand exhibit low frequency variability. This low frequency variability is thought to be predominantly driven by socio-economic changes rather than temperature variation. Once this variability is removed, both daily electricity and gas demand have a strong anti-correlation with temperature (r elec = −0.90 , r gas = −0.94). However these correlations are inflated by the changing demand–temperature relationship during spring and autumn. Once the annual cycles of temperature and demand are removed, the correlations are and . Winter then has the strongest demand–temperature relationship, during which a 1 °C reduction in daily temperature typically gives a ~1% increase in daily electricity demand and a 3%–4% increase in gas demand. Extreme demand periods are assessed using detrended daily temperature observations from 1772. The 1 in 20 year peak day electricity and gas demand estimates are, respectively, 15% (range 14%–16%) and 46% (range 44%–49%) above their average winter day demand during the last decade. The risk of demand exceeding recent extreme events, such as during the winter of 2009/2010, is also quantified
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