6,461 research outputs found
Meteorological regimes for the classification of aerospace air quality predictions for NASA-Kennedy Space Center
A method is described for developing a statistical air quality assessment for the launch of an aerospace vehicle from the Kennedy Space Center in terms of existing climatological data sets. The procedure can be refined as developing meteorological conditions are identified for use with the NASA-Marshall Space Flight Center Rocket Exhaust Effluent Diffusion (REED) description. Classical climatological regimes for the long range analysis can be narrowed as the synoptic and mesoscale structure is identified. Only broad synoptic regimes are identified at this stage of analysis. As the statistical data matrix is developed, synoptic regimes will be refined in terms of the resulting eigenvectors as applicable to aerospace air quality predictions
Force and energy dissipation variations in non-contact atomic force spectroscopy on composite carbon nanotube systems
UHV dynamic force and energy dissipation spectroscopy in non-contact atomic
force microscopy were used to probe specific interactions with composite
systems formed by encapsulating inorganic compounds inside single-walled carbon
nanotubes. It is found that forces due to nano-scale van der Waals interaction
can be made to decrease by combining an Ag core and a carbon nanotube shell in
the Ag@SWNT system. This specific behaviour was attributed to a significantly
different effective dielectric function compared to the individual
constituents, evaluated using a simple core-shell optical model. Energy
dissipation measurements showed that by filling dissipation increases,
explained here by softening of C-C bonds resulting in a more deformable
nanotube cage. Thus, filled and unfilled nanotubes can be discriminated based
on force and dissipation measurements. These findings have two different
implications for potential applications: tuning the effective optical
properties and tuning the interaction force for molecular absorption by
appropriately choosing the filling with respect to the nanotube.Comment: 22 pages, 6 figure
Critical care provision after colorectal cancer surgery
Background: Colorectal cancer (CRC) is the 2nd largest cause of cancer related mortality in the UK with 40 000
new patients being diagnosed each year. Complications of CRC surgery can occur in the perioperative period that
leads to the requirement of organ support. The aim of this study was to identify pre-operative risk factors that
increased the likelihood of this occurring.
Methods: This is a retrospective observational study of all 6441 patients who underwent colorectal cancer surgery
within the West of Scotland Region between 2005 and 2011. Logistic regression was employed to determine
factors associated with receiving postoperative organ support.
Results: A total of 610 (9 %) patients received organ support. Multivariate analysis identified age ≥65, male gender,
emergency surgery, social deprivation, heart failure and type II diabetes as being independently associated with
organ support postoperatively. After adjusting for demographic and clinical factors, patients with metastatic disease
appeared less likely to receive organ support (p = 0.012).
Conclusions: Nearly one in ten patients undergoing CRC surgery receive organ support in the post operative
period. We identified several risk factors which increase the likelihood of receiving organ support post operatively.
This is relevant when consenting patients about the risks of CRC surgery
Nanotube field of C60 molecules in carbon nanotubes: atomistic versus continuous tube approach
We calculate the van der Waals energy of a C60 molecule when it is
encapsulated in a single-walled carbon nanotube with discrete atomistic
structure. orientational degrees of freedom and longitudinal displacements of
the molecule are taken into account, and several achiral and chiral carbon
nanotubes are considered. A comparison with earlier work where the tube was
approximated by a continuous cylindrical distribution of carbon atoms is made.
We find that such an approximation is valid for high and intermediate tube
radii; for low tube radii, minor chirality effects come into play. Three
molecular orientational regimes are found when varying the nanotube radius.Comment: 14 pages, 9 figures, accepted for publication in Phys. Rev.
Glueball matrix elements on anisotropic lattices
We describe a lattice calculation of the matrix elements relevant for
glueball production in radiative decays. The techniques for such a
calculation on anisotropic lattices with an improved action are outlined. We
present preliminary results showing the efficacy of the computational method.Comment: 3 pages (LaTeX), 3 figures (PostScript), Presented at Lattice '9
Stringent Phenomenological Investigation into Heterotic String Optical Unification
For the weakly coupled heterotic string (WCHS) there is a well-known factor
of twenty conflict between the minimum string coupling unification scale,
Lambda_H ~5x10^(17) GeV, and the projected MSSM unification scale, Lambda_U ~
2.5x10^(16) GeV, assuming an intermediate scale desert (ISD). Renormalization
effects of intermediate scale MSSM-charged exotics (ISME) (endemic to
quasi-realistic string models) can resolve this issue, pushing the MSSM scale
up to the string scale. However, for a generic string model, this implies that
the projected Lambda_U unification under ISD is accidental. If the true
unification scale is 5.0x10^(17) GeV, is it possible that illusionary
unification at 2.5x10^(17) GeV in the ISD scenario is not accidental? If it is
not, then under what conditions would the assumption of ISME in a WCHS model
imply apparent unification at Lambda_U when ISD is falsely assumed? Geidt's
"optical unification" suggests that Lambda_U is not accidental, by offering a
mechanism whereby a generic MSSM scale Lambda_U < Lambda_H is guaranteed. A
WCHS model was constructed that offers the possibility of optical unification,
depending on the availability of anomaly-cancelling flat directions meeting
certain requirements. This paper reports on the systematic investigation of the
optical unification properties of the set of stringent flat directions of this
model. Stringent flat directions can be guaranteed to be F-flat to all finite
order (or to at least a given finite order consistent with electroweak scale
supersymmetry breaking) and can be viewed as the likely roots of more general
flat directions. Analysis of the phenomenology of stringent flat directions
gives an indication of the remaining optical unification phenomenology that
must be garnered by flat directions developed from them.Comment: standard latex, 18 pages of tex
Reply to Isgur's Comments on Valence QCD
We reply to Nathan Isgur's critique that is directed at some of the
conclusions drawn from the lattice simulation of valence QCD, regarding the
valence quark model and effective chiral theories.Comment: 12 pages, 6 figure
Testing the proposed link between cosmic rays and cloud cover
A decrease in the globally averaged low level cloud cover, deduced from the
ISCCP infra red data, as the cosmic ray intensity decreased during the solar
cycle 22 was observed by two groups. The groups went on to hypothesise that the
decrease in ionization due to cosmic rays causes the decrease in cloud cover,
thereby explaining a large part of the presently observed global warming. We
have examined this hypothesis to look for evidence to corroborate it. None has
been found and so our conclusions are to doubt it. From the absence of
corroborative evidence, we estimate that less than 23%, at the 95% confidence
level, of the 11-year cycle change in the globally averaged cloud cover
observed in solar cycle 22 is due to the change in the rate of ionization from
the solar modulation of cosmic rays
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