25,684 research outputs found
Deep Reconditioning Testing for near Earth Orbits
The problems and benefits of deep reconditioning to near Earth orbit missions with high cycle life and shallow discharge depth requirements is discussed. A simple battery level approach to deep reconditioning of nickel cadmium batteries in near Earth orbit is considered. A test plan was developed to perform deep reconditioning in direct comparison with an alternative trickle charge approach. The results demonstrate that the deep reconditioning procedure described for near Earth orbit application is inferior to the alternative of trickle charging
New insights into the influence of ice on the coastal marine environment of the Beaufort Sea, Alaska
Areal patterns from field data and ERTS-1 imagery have shown a close relationship between geologic processes and the influence of sea ice along Alaska's northern coast, perhaps the nation's least known continental margin. Ice acts as; (1) a bottom-gouging agent; (2) an influence on water circulation; (3) a carrier of sediments; and (4) an influence on water types
On a q-analogue of the multiple gamma functions
A -analogue of the multiple gamma functions is introduced, and is shown to
satisfy the generalized Bohr-Morellup theorem. Furthermore we give some
expressions of these function.Comment: 8 pages, AMS-Late
The use and abuse of gastrointestinal suction in the treatment of intestinal obstruction
An attempt has been made to investigate the rational
behind the use of suction in cases Of intestinal obstruction.
It would appear that the effect of distension with, or without
a compromisation of the blood supply, is the initial condition.
The effect of this distension leads to devitalisation and
circulatory embarrassment, resulting in conditions which are
conducive for the proliferation of bacteria and the production
of the clinical picture of toxaemia. The effect on the colon
is additionally complicated by the presence of the eaecum
which has a distinct tendency t® perforate under pressure
and lead to peritonitis.The importance of differentiating strangulated from
non-strangulated obstruction is stressed and the negative finding
of no clear points on which t© base this distinction is noted.
On© view to be taken is that of Barker (1963) who describes
operating on all cases of obstruction past a certain time limit;
whereas Waldron and Hampton (I961) report an overall mortality
of 1436, Baker in 126 cases of early obstruction had
mortality and in 49 late cases 10.6% mortality - an average
of 5.2%. He argues that complete surgical decompression has
the advantages of 1) the site of obstruction is visualised
and freed 2) respiratory embarrassment is relieved 3) the
wound is more easily closed 4) there is less trauma to the
viscera and 5) the opportunity of recurrent obstruction is
reduced.With the safety factor increased by modern surgical
techniques, anaesthetics an powerful antibiotics some indications
for suction, or the extensive use of suction had been eliminated.The greatest difference of opinion would appear to
revolve around the choice of the proper moment for operative
correction. All agree that strangulated obstruction and
obstruction of the colon are indications for surgery, but the
role of suction in simple obstruction is in doubt. Some,
like Barker, consider the diagnosis of obstruction whatever
the type, to be an indication for surgery. Others, advocate
operative techniques after a trial by suction although ©Iran
Wangansteen admits that surgery is the mainstay of treatment
in this conditionDeaths occurring in any series are important to
analyse. Miller (1929) reported a mortality rate of 65%
at the Charity Hospital in Hew Orleans. Tendler and
Cartwright reported mortality rates of 51% from 1923/1932 ,
then 26% from 1933/46 and 8% from 1947/1953. Turner reported
100 consecutive cases from each of three decades and found
a mortality of 27% in 1929, 21% in 1939 and 4% in 1949.
Missed strangulated obstruction always led to death for
although suction will remove the toxic products from a
strangulated segment of gut, it will not do so in a closed
loop situation. Even in the simple strangulated case, suction
only acts to delay the inevitable operation. The question of
time is also of importance as regards the production of
complications from the mechanical effects of the suction tub®.
It should be noted however, that there is one report of a
patient with an indwelling nasogastric tube for 47 days without
complication. This is exceptional and many complications arise
in the first 48 hours of use.Post-operatively the picture is even more confused but
with observations of the stomach after vagotomy the position
is being resolved. Some consider that suction is absolutely
necessary after operation involving vagotomy, believing that
the stomach is flaccid and distends to a considerable size.
It is true that a reduction in the contractile force dees occur,
but intragastric pressure and aural tone is increased. Numerous
reports have been read about the advantages of tubeless
post-operative management and the remarkable degree of success
it enjoys.As a development of heart pacing methods, Bilgutay et al
(1962) describes a method ©f intestinal pacing to restore
motility in ileus. He reports that these patients so treated
have a lower incidence of complications and a shorter
hospitalisation. The gut regaining its motility in 6/20 hours
as compared with patients treated by suction in which the gut
returns to normal in some 55 hours or more. This is extremely
interesting, especially as Smith's (1965) work makes a plea
for the treatment of paralytic ileus to be directed at the
inhibition produced by trauma, rather than direct muscle
stimulation
Optimisation of confinement in a fusion reactor using a nonlinear turbulence model
The confinement of heat in the core of a magnetic fusion reactor is optimised
using a multidimensional optimisation algorithm. For the first time in such a
study, the loss of heat due to turbulence is modelled at every stage using
first-principles nonlinear simulations which accurately capture the turbulent
cascade and large-scale zonal flows. The simulations utilise a novel approach,
with gyrofluid treatment of the small-scale drift waves and gyrokinetic
treatment of the large-scale zonal flows. A simple near-circular equilibrium
with standard parameters is chosen as the initial condition. The figure of
merit, fusion power per unit volume, is calculated, and then two control
parameters, the elongation and triangularity of the outer flux surface, are
varied, with the algorithm seeking to optimise the chosen figure of merit. A
two-fold increase in the plasma power per unit volume is achieved by moving to
higher elongation and strongly negative triangularity.Comment: 32 pages, 8 figures, accepted to JP
Adelic Integrable Systems
Incorporating the zonal spherical function (zsf) problems on real and
-adic hyperbolic planes into a Zakharov-Shabat integrable system setting, we
find a wide class of integrable evolutions which respect the number-theoretic
properties of the zsf problem. This means that at {\it all} times these real
and -adic systems can be unified into an adelic system with an -matrix
which involves (Dirichlet, Langlands, Shimura...) L-functions.Comment: 23 pages, uses plain TE
Effective action for Dirac fields in a constant electromagnetic background
We obtain, through zeta function methods, the one-loop effective action for massive Dirac fields in the presence of a uniform, but otherwise general, electromagnetic background. We show the agreement of our result with previous ones, concerning particular limit cases
Independent Orbiter Assessment (IOA): FMEA/CIL assessment
The McDonnell Douglas Astronautics Company (MDAC) was selected to perform an Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL). Direction was given by the Orbiter and GFE Projects Office to perform the hardware analysis and assessment using the instructions and ground rules defined in NSTS 22206. The IOA analysis featured a top-down approach to determine hardware failure modes, criticality, and potential critical items. To preserve independence, the analysis was accomplished without reliance upon the results contained within the NASA and Prime Contractor FMEA/CIL documentation. The assessment process compared the independently derived failure modes and criticality assignments to the proposed NASA post 51-L FMEA/CIL documentation. When possible, assessment issues were discussed and resolved with the NASA subsystem managers. Unresolved issues were elevated to the Orbiter and GFE Projects Office manager, Configuration Control Board (CCB), or Program Requirements Control Board (PRCB) for further resolution. The most important Orbiter assessment finding was the previously unknown stuck autopilot push-button criticality 1/1 failure mode. The worst case effect could cause loss of crew/vehicle when the microwave landing system is not active. It is concluded that NASA and Prime Contractor Post 51-L FMEA/CIL documentation assessed by IOA is believed to be technically accurate and complete. All CIL issues were resolved. No FMEA issues remain that have safety implications. Consideration should be given, however, to upgrading NSTS 22206 with definitive ground rules which more clearly spell out the limits of redundancy
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