63,660 research outputs found
Collision Tumour of the Ampulla of Vater: Carcinoid and Adenocarcinoma
Obstructive jaundice is most commonly due to luminal stones or lesions of the head of the pancreas and more rarely ampullary and primary common bile duct lesions. Obstruction due to lesions of the ampulla of Vater may be due to adenocarcinoma which has a significantly better long term prognosis than carcinomas located in the head of the pancreas. A case is presented where two tumours were identified at the ampulla of Vater of the resected specimen one an adenocarcinoma and the other a carcinoid tumour representing a collision tumour
Ship-based nitric acid measurements in the Gulf of Maine during New England Air Quality Study 2002
Gas phase nitric acid (HNO3) was measured at 5-min resolution on board the National Oceanographic and Atmospheric Administration (NOAA) research vessel Ronald H. Brown during the second leg (29 July to 10 August) of the New England Air Quality Study (NEAQS) 2002 cruise. A primary objective of the cruise was to improve understanding of the oxidation of NOx in, and removal of the oxidation products from, the polluted marine boundary layer east of northeastern North America. For the first 9 days of this leg the ship remained north of Cape Cod, and the cruise track did not extend much farther north than the New Hampshire-Maine border. During this period, HNO3 averaged 1.1 ppb and accounted for 19% of total reactive nitrogen oxides (measured NOy). On all days, peak HNO3 mixing ratios were observed in the early afternoon (average 2.3 ppb), at levels twofold to fourfold higher than the minima around sunrise and sunset. In these daytime peaks, HNO3/NOy averaged 28%. There were secondary nighttime peaks of HNO3 (0.9 ppb average), when HNO3 accounted for 16% of total reactive nitrogen oxides. This pronounced diurnal pattern confirms that production, and subsequent deposition, of HNO3 in the polluted marine boundary layer downwind of New England removes a significant fraction of the NOx exported to the atmosphere over the Gulf of Maine. Nitric acid was correlated with O3, particularly during the early afternoon interval when both molecules reached maximum mixing ratios (R2 = 0.66). The ozone production efficiency (OPE) inferred from the slope (10 ppb O3/ppb HNO3) was similar to the OPE of 9 estimated at the Atmospheric Investigation, Regional Modeling, Analysis and Prediction (AIRMAP) Thompson Farm station in coastal New Hampshire during the study period
Experimental Persistence Probability for Fluctuating Steps
The persistence behavior for fluctuating steps on the surface was determined by analyzing time-dependent
STM images for temperatures between 770 and 970K. The measured persistence
probability follows a power law decay with an exponent of . This is consistent with the value of predicted for
attachment/detachment limited step kinetics. If the persistence analysis is
carried out in terms of return to a fixed reference position, the measured
persistence probability decays exponentially. Numerical studies of the Langevin
equation used to model step motion corroborate the experimental observations.Comment: LaTeX, 11 pages, 4 figures, minor changes in References sectio
Fast pyrolysis of halogenated plastics recovered from waste computers
The disposal of waste computers is an issue that is gaining increasing interest around the world. In this paper, results from the fast pyrolysis in a fluidized bed reactor of three different waste computer monitor casings composed of mainly acrylonitrile-butadiene-styrene (ABS) copolymer and two different waste computer body casings composed of mostly poly(vinyl chloride) (PVC) type polymers are presented. Preliminary characterization of the waste plastics was investigated using coupled thermogravimetric analysis-Fourier transform infrared spectrometry (TGA-FT-IR). The results showed that the plastics decomposed in two stages. For the ABS-containing monitor casings, aromatic and aliphatic material were released in the first and second stages. The PVC-containing computer body casing samples showed a first-stage evolution of HCl and a second stage evolution of aromatic and aliphatic material and further HCl. In addition, each of the five plastics was fast-pyrolyzed in a laboratory-scale fluidized bed reactor at 500 °C. The fluidized bed pyrolysis led to the conversion of most of the plastics to pyrolysis oil, although the two PVC computer body cases produced large quantities of HCl. The pyrolysis oils were characterized by GC-MS and it was found that they were chemically very heterogeneous and contained a wide range of aliphatic, aromatic, halogenated, oxygenated, and nitrogenated compounds
Entanglement Measure for Composite Systems
A general description of entanglement is suggested as an action realized by
an arbitrary operator over given disentangled states. The related entanglement
measure is defined. Because of its generality, this definition can be employed
for any physical systems, pure or mixed, equilibrium or nonequilibrium, and
characterized by any type of operators, whether these are statistical
operators, field operators, spin operators, or anything else. Entanglement of
any number of parts from their total ensemble forming a multiparticle composite
system can be determined. Interplay between entanglement and ordering,
occurring under phase transitions, is analysed by invoking the concept of
operator order indices.Comment: 6 pages, Revte
The Short Rotation Period of Nereid
We determine the period, p = 11.52 \pm 0.14 h, and a light curve peak-to-peak
amplitude, a = 0.029 \pm 0.003 magnitudes, of the Neptunian irregular satellite
Nereid. If the light curve variation is due to albedo variations across the
surface, rather than solely to the shape of Nereid variations, the rotation
period would be a factor of two shorter. In either case, such a rotation period
and light curve amplitude, together with Nereid's orbital period, p=360.14
days, imply that Nereid is almost certainly in a regular rotation state, rather
than the chaotic rotation state suggested by Schaefer and Schaefer (1988,2000)
and Dobrovolskis (1995).
Assuming that Nereid is perfectly spherical, the albedo variation is 3%
across the observed surface. Assuming a uniform geometric albedo, the observed
cross sectional area varies by 3%. We caution that the lightcurve found in this
paper only sets limits on the combination of albedo and physical irregularity
and that we cannot determine the orientation of Nereid's spin axis from our
data.Comment: Accepted by ApJ Letters, 11 pages (incl. 1 figure
UK medical students’ perspectives on practical prescribing teaching and learning provisions: a cross-sectional survey
Purpose
To determine medical students’ perspectives on the provision for the teaching and learning of processes that lead to and include the writing of a clear, safe and legal prescription (practical prescribing) in UK medical schools.
Methods
We designed a cross-sectional survey of UK medical students in years three, four and five. Students were asked about their experiences and views of practical prescribing teaching and learning they had encountered on their medical course.
Results
A total of 1023 medical students responded (7% response rate), from 25 UK medical schools: 22%, 37% and 41% in the third, fourth and final years, respectively. Teaching of practical prescribing was widespread, with 94.3% of final year (n = 396, 95% confidence interval [CI] = 92–97%), 86.8% of fourth year (n = 328, CI = 83–90%) and 73.8% of third year (n = 166, CI = 67–80%) students reporting they had received it. Availability of this teaching appeared to vary by medical school. Self-directed learning was the most frequently reported mode of delivery (90.9%, n = 809). Validated pre-prescribing and simulation were perceived by students in each year group as the most effective methods. Clinical pharmacologists, clinical pharmacists and junior doctors were perceived by the students as being the most effective professional groups at teaching practical prescribing.
Conclusions
UK medical students reported a variety of methods utilised in the teaching and learning of practical prescribing. However, methods they perceived to be very effective (simulation and pre-prescribing) do not appear to be widely available or are only reserved for the final year of study. Combining such methods with involvement of professional groups perceived to be most effective should be explored
Factors affecting temperature changes in dressed poultry during refrigeration
Publication authorized October 27, 1941.Includes bibliographical references (pages 37-39)
Transport, magnetic and superconducting properties of RuSr2RCu2O8 (R= Eu, Gd) doped with Sn
Ru{1-x}Sn{x}Sr2EuCu2O8 and Ru{1-x}Sn{x}Sr2GdCu2O8 have been comprehensively
studied by microwave and dc resistivity and magnetoresistivity and by the dc
Hall measurements. The magnetic ordering temperature T_m is considerably
reduced with increasing Sn content. However, doping with Sn leads to only
slight reduction of the superconducting critical temperature T_c accompanied
with the increase of the upper critical field B_c2, indicating an increased
disorder in the system and a reduced scattering length of the conducting holes
in CuO2 layers. In spite of the increased scattering rate, the normal state
resistivity and the Hall resistivity are reduced with respect to the pure
compound, due to the increased number of itinerant holes in CuO2 layers, which
represent the main conductivity channel. Most of the electrons in RuO2 layers
are presumably localized, but the observed negative magnetoresistance and the
extraordinary Hall effect lead to the conclusion that there exists a small
number of itinerant electrons in RuO layers that exhibit colossal
magnetoresistance.Comment: 10 pages, 9 figure
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