70,696 research outputs found
Skeletal stressing method and apparatus Patent
Method and apparatus for applying compressional forces to skeletal structure of subject to simulate force during ambulatory condition
Programmable physiological infusion
A programmable physiological infusion device and method are provided wherein a program source, such as a paper tape, is used to actuate an infusion pump in accordance with a desired program. The system is particularly applicable for dispensing calcium in a variety of waveforms
Network-Configurations of Dynamic Friction Patterns
The complex configurations of dynamic friction patterns-regarding real time
contact areas- are transformed into appropriate networks. With this
transformation of a system to network space, many properties can be inferred
about the structure and dynamics of the system. Here, we analyze the dynamics
of static friction, i.e. nucleation processes, with respect to "friction
networks". We show that networks can successfully capture the crack-like shear
ruptures and possible corresponding acoustic features. We found that the
fraction of triangles remarkably scales with the detachment fronts. There is a
universal power law between nodes' degree and motifs frequency (for triangles,
it reads T(k)\proptok{\beta} ({\beta} \approx2\pm0.4)). We confirmed the
obtained universality in aperture-based friction networks. Based on the
achieved results, we extracted a possible friction law in terms of network
parameters and compared it with the rate and state friction laws. In
particular, the evolutions of loops are scaled with power law, indicating the
aggregation of cycles around hub nodes. Also, the transition to slow rupture is
scaled with the fast variation of local heterogeneity. Furthermore, the motif
distributions and modularity space of networks -in terms of withinmodule degree
and participation coefficient-show non-uniform general trends, indicating a
universal aspect of energy flow in shear ruptures
Topological Complexity of Frictional Interfaces: Friction Networks
Through research conducted in this study, a network approach to the
correlation patterns of void spaces in rough fractures (crack type II) was
developed. We characterized friction networks with several networks
characteristics. The correlation among network properties with the fracture
permeability is the result of friction networks. The revealed hubs in the
complex aperture networks confirmed the importance of highly correlated groups
to conduct the highlighted features of the dynamical aperture field. We found
that there is a universal power law between the nodes' degree and motifs
frequency (for triangles it reads T(k)\proptok{\beta} ({\beta}
\approx2\pm0.3)). The investigation of localization effects on eigenvectors
shows a remarkable difference in parallel and perpendicular aperture patches.
Furthermore, we estimate the rate of stored energy in asperities so that we
found that the rate of radiated energy is higher in parallel friction networks
than it is in transverse directions. The final part of our research highlights
4 point sub-graph distribution and its correlation with fluid flow. For shear
rupture, we observed a similar trend in sub-graph distribution, resulting from
parallel and transversal aperture profiles (a superfamily phenomenon)
Weight simulator
Device applies compressive force to bone to minimize loss of bone calcium during weightlessness or bedrest. Force is applied through weights, or hydraulic, pneumatic or electrically actuated devices. Device is lightweight and easy to maintain and operate
Prevalence of deliberate self harm and attempted suicide within contemporary Goth youth subculture: longitudinal cohort study
<b>Objective</b> To investigate whether deliberate self harm is associated with contemporary Goth youth subculture.
<b>Design</b> Longitudinal cohort study.
<b>Setting</b> School and community based study of young people living in the Central Clydeside Conurbation, Scotland.
<b>Participants</b> 1258 people aged 19, surveyed in 2002-4 and followed-up since age 11 (1994).
<b>Main outcome measures</b> Lifetime prevalence of self harm and attempted suicide and their association with Goth youth subculture, before and after adjusting for confounders.
<b>Results</b> Identification as belonging to the Goth subculture was strongly associated with lifetime self harm and attempted suicide, with a prevalence of 53% and 47%, respectively among the most highly identified group, and evidence for a dose-response relation. Adjusting for potential confounders did not significantly attenuate this association. Analysis of other youth subcultures showed that this effect was primarily associated with Goth subculture.
<b>Conclusions</b> Identification as belonging to the Goth subculture was the best predictor of self harm and attempted suicide. Although based on small numbers, additional longitudinal analysis suggests both selection and modelling mechanisms are involved, selection mechanisms possibly being more likely
Programmed physiological infusion system
Infusion system delivers incremental volumes from a reservoir with a piston pump at a rate that varies in time and follows the envelope of a preprogrammed curve
A closer look at a coronal loop rooted in a sunspot umbra
Extreme UV (EUV) and X-ray loops in the solar corona connect regions of
enhanced magnetic activity, but they are not usually rooted in the dark umbrae
of sunspots because the strong magnetic field found there suppresses
convection. This means that the Poynting flux of magnetic energy into the upper
atmosphere is not significant within the umbra as long as there are no light
bridges or umbral dots. Here we report a rare observation of a coronal loop
rooted in the dark umbra of a sunspot without any traces of light bridges or
umbral dots. We used the slit-jaw images and spectroscopic data from IRIS and
concentrate on the line profiles of O IV and Si IV that show persistent strong
redshifted components in the loop rooted in the umbra. Using the ratios of O
IV, we can estimate the density and thus investigate the mass flux. The coronal
context and temperature diagnostics of these observations is provided through
the EUV channels of AIA. The coronal loop, embedded within cooler downflows,
hosts supersonic downflows. The speed of more than 100 km s is on the
same order of magnitude in the transition region lines of O IV and Si IV, and
is even seen at comparable speed in the chromospheric Mg II lines. At a
projected distance of within of the footpoint, we see a shock transition
to smaller downflow speeds of about 15 km s being consistent with mass
conservation across a stationary isothermal shock. We see no direct evidence
for energy input into the loop because the loop is rooted in the dark uniform
part of the umbra with no light bridges or umbral dots near by. Thus one might
conclude that we are seeing a siphon flow driven from the footpoint at the
other end of the loop. However, for a final result data of similar quality at
the other footpoint are needed, but this is too far away to be covered by the
IRIS field of view.Comment: Accepted for publication in Astronomy and Astrophysics (abridged
abstract
Fixed and Flexible Rates: A Renewal of The Debate
The paper reviews the extent to which a decade of analysis and experience has altered thinking about the choice of an exchange rate system. The advantages of flexible rates are viewed to have been exaggerated. They do not permit governments to have permanently higher rates of economic activity at the expense of higher inflation as some thought. Further, the slow speed of adjustment to relative price changes limits the contribution of flexible rates to external adjustment in the short-run, and the degree of insulation from external influences that they provide. Finally, flexible rates tend to be fluctuating rates, and, although there is little empirical evidence so far showing that the fluctuations have had adverse effects on trade and capital flows, the exchange rate instability more than any other factor has led to a certain disillusionment with the floating rate system. Notwithstanding the drawbacks of flexible rates, there will be a continuing need for exchange rate flexibility over the next few years, and some analysis is given of the problems of achieving greater stability under flexible rates or the requisite amount of flexibility under pegged rates.
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