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21.
J De Meester GG Persijn T Wujciak G Opelz Y Vanrenterghem 《Canadian Metallurgical Quarterly》1998,66(9):1154-1159
BACKGROUND: Upon the availability of a cadaveric donor kidney, a delicate allocation process precedes every transplantation. A remodeled Eurotransplant Kidney Allocation System (ETKAS)-derived from simulation studies-was installed in March 1996. The purpose was to adjust long waiting times and international exchange balances, while aiming at an optimal HLA-mismatch distribution. The new ETKAS consisted of a point-score system that was 100% patient oriented. METHODS: The impact of the new ETKAS on the composition of the waiting list, and the outcome of the allocation procedures during its first year, were evaluated and compared with the results obtained in 1995. RESULTS: The percentage of long-waiting patients and of patients with poorly matchable HLA phenotype increased significantly, from 9% to 19% and from 19% to 29%, respectively. Zero HLA-A-, HLA-B-, HLA-DR-mismatched patients still comprised 23% of the kidney transplant activity. The kidney exchange of the different Eurotransplant countries became balanced within 4 months; this persisted during the rest of the year. Pediatric patients had a high transplantation rate due to an assignment of extra points. The composition of the waiting list showed, after 1 year, fewer long-waiting patients and fewer patients with rare HLA phenotypes. CONCLUSIONS: The new ETKAS was able in its first year to meet the goals set at its introduction. In comparison with the old ETKAS, there was a better trade-off between HLA matching and waiting time. The value of computer simulation studies has been demonstrated impressively in the context of organ allocation. 相似文献
22.
G. R. Collier F. McL Collier A. Sanigorski K. Walder D. Cameron-Smith A. J. Sinclair 《Lipids》1997,32(3):317-322
Recently it has been postulated that membrane fatty acid composition may be involved in the pathogenesis of insulin resistance
and non-insulin dependent diabetes mellitus (NIDDM). The aim of this study was to determine whether alterations in tissue
phospholipid (PL) fatty acids are present in hyperglycemic and hyperinsulinemic Psammomys obesus. On a native diet of salt bush, P. obesus (Israeli sand rat) remains lean and free of diabetes; however, when placed on a normal laboratory chow, a significant proportion
of these animals develops a number of metabolic disorders associated with NIDDM, providing an ideal animal model of obesity
and NIDDM. Four groups of mature P. obesus were studied: group A; normoglycemic and normoinsulinemic; group B: normoglycemic and hyperinsulinemic; group C: hyperglycemic
and hyperinsulinemic; and group D: hyperglycemic hypoinsulinemic. In liver and red gastrocnemius muscle, there were no significant
differences between groups, A, B, and in fatty acid composition of PL. Minor differences in individual fatty acids were demonstrated
in group D animals (increased liver 20∶4n-6 and increased muscle 22∶5n-3); however, the unsaturation indices in liver and
muscle were not significantly different between any of the groups. In considering that the minor changes in group D animals
were not demonstrated in hyperinsulinemic group B animals or hyperglycemic, hyperinsulinemic group C animals, it is likely
that the differences in group D animals were secondary to the more severe disturbances in glucose homeostasis and hypoinsulinemia
present in these animals. The results of this study suggest that in this rodent diabetic model significant disturbances in
glucose homeostasis and hyperinsulinemia may develop independently of changes in tissue fatty acid composition. 相似文献
23.
The essential fatty acids do not have identical roles in nutrition. Linoleic acid (LA) accumulates throughout the body of
most mammals, whereas α-linolenic acid (ALA) is rarely found in tissue lipids to the same extent as LA. It has been argued
that this is the result of metabolism of ALA to docosahexaenoic acid (DHA) or that ALA is rapidly β-oxidized to acetyl CoA
and CO2. In this study, we consider the effect of high and low ALA levels on the tissue distribution of ALA and other n-3 polyunsaturated
fatty acids (PUFA) in all tissues. Guinea pigs were fed one of two defined diets for 3 wk from wearning with both diets containing
1.8% (by weight) of LA and either 1.7% ALA or 0.03% ALA. The high ALA diet was associated with significantly increased ALA
levels in all tissues except the brain and significantly increased levels of long-chain n-3 PUFA in all tissues except intestines,
brain, carcass, and skin. The long-chain n-3 PUFA content of the whole body was less than 5% of that of the ALA content in
both diet groups, and the major long-chain n-3 PUFA (>66% of total) in the body was 22∶5n−3. The brain was the only tissue
where the DHA content exceeded that of 22∶5n−3. On the low ALA diet, there appeared to be conservation of ALA based on a comparison
of the ratio of LA to ALA in the tissues compared with that in the diet. On the high ALA diet there was a loss of ALA relative
to LA in the tissues compared with the diet. These studies suggest that the low levels of tissue ALA in the guinea pig are
likely the result of β-oxidation or excretion via the skin and fur rather than metabolism to DHA. 相似文献
24.
S. A. G. R. Karunathilaka N. A. Hampson T. P. Haas R. Leek T. J. Sinclair 《Journal of Applied Electrochemistry》1981,11(5):573-582
The impedances of small (2400 mA h) alkaline Zn-HgO cells have been measured in the range 10 kHz-0.001 Hz at various states of charge from fully charged to fully discharged. The behaviour of the cell conforms to that expected for rate control by charge transfer at the zinc electrode and diffusion in solution. At low frequencies there is a relaxation in the diffusive circuit elements which ultimately results in a complete suppression of the capacitative component of the impedance at zero frequency. The low-frequency behaviour is analogous to convective diffusion and is due to the effective distance between the electrodes being small compared with the characteristic length (D/)1/2. The magnitude of the charge transfer resistance is the best measure of the state of charge.Nomenclature
a
effective electrode separation
-
C
DL
double-layer capacitance of cell
-
C
R
capacitative component of cell impedance
- C
concentration difference
-
D
percentage discharge in Equation 12
-
D
i
diffusion coefficient of speciesi
-
R
ohmic resistance of cell
-
R
R
resistive component of cell Faradaic impedance
-
Ui
constant defined by Equation 10
-
Z
total cell impedance
-
Z
F
cell Faradaic impedance
-
Z
F
cell impedance modified for porosity effect
-
Z
x
cell impedance of Faradaic component plus double layer
-
cell Warburg coefficient (slope ofR
R and 1/C
Rversus su}-1/2)
-
C
Warburg coefficient calculated fromC
r values
-
i
cell Warburg coefficient for speciesi
-
Warburg coefficient calculated fromR
R values
-
dihedral angle of tail of Sluyters plot (after coming-off high-frequency semicircle)
-
angular frequency 相似文献
25.
Oi-Lam Ng Nathalie Sinclair 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(1):84-101
AbstractIn this article, we report on two lessons aimed at introducing junior high school students to the idea of shearing in a touchscreen dynamic geometry environment. By using shearing, we hoped to shift students’ attention away from a formula-driven, computational conception of area toward a more geometric one. We found that the students were able to solve several problems involving the comparison of polygons based on verbal and diagrammatic explanations. We describe the features of the touchscreen dynamic geometry technology that supported their learning, as well as the specific role that the teacher played in modeling students’ reasoning about area. 相似文献
26.
J. Jiang Fanghua Mei W. J. Meng G. B. Sinclair Sunggook Park 《Microsystem Technologies》2008,14(6):815-819
For direct imprinting of metals, hard materials such as diamond and SiC have been used to construct mold inserts in preference
to Si, despite the ease in fabricating Si-based micro-/nano- scale structures. In this communication, we demonstrate that
micron scale Al structures can be replicated with good fidelity at room temperature by compression molding with Si inserts
without incurring insert damage. We further report on results of a finite element analysis of the mechanics of the molding
process. The finite element results provide some understanding of the observed lack of damage to the Si inserts. 相似文献
27.
T
c data are reported for powders of cation-stoichiometric Bi2Sr2CaCu2O and for nonstoichiometric samples based on the three mechanisms BiSr, SrCa and Sr vacancy. For each, the T
c values depend critically on the final oxygen contents, which were varied by heating samples in either O2 or N2 at different temperatures. Stoichiometric Bi2Sr2CaCu2O has the highest T
c, 92 K, obtained after heating in O2 at 820 °C. Heating in O2 at lower temperatures gives rise to overdoping and T
c decreases to 60 K. The other cation compositions show a smaller maximum T
c but also less reduction in T
c on overdoping. Under-doped samples, with reduced T
c values were obtained on heating in N2. These data, together with selected literature results, lead to a unified picture of the variation of T
c with cation composition and oxygen content. 相似文献
28.
29.
Systems integration 总被引:1,自引:0,他引:1
The paper presents a view of systems integration, from an ergonomics/human factors perspective, emphasising the process of systems integration as is carried out by humans. The first section discusses some of the fundamental issues in systems integration, such as the significance of systems boundaries, systems lifecycle and systems entropy, issues arising from complexity, the implications of systems immortality, and so on. The next section outlines various generic processes for executing systems integration, to act as guides for practitioners. These address both the design of the system to be integrated and the preparation of the wider system in which the integration will occur. Then the next section outlines some of the human-specific issues that would need to be addressed in such processes; for example, indeterminacy and incompleteness, the prediction of human reliability, workload issues, extended situation awareness, and knowledge lifecycle management. For all of these, suggestions and further readings are proposed. Finally, the conclusions section reiterates in condensed form the major issues arising from the above. 相似文献
30.
GG Stone MM Chengappa RD Oberst NH Gabbert S McVey KJ Hennessy M Muenzenberger J Staats 《Canadian Metallurgical Quarterly》1993,5(3):378-385
The polymerase chain reaction was employed to correlate Salmonella serovars isolated from fecal material of greyhounds suffering from gastroenteritis with those isolated from the diet fed to the greyhounds prior to onset of diarrhea. Kennels around the Abilene, Kansas, area were contacted and supplied with materials needed to collect a portion of the diet each day. With the onset of diarrhea, the kennels were instructed to ship the fecal material and diet from the previous 10 days to the laboratory for testing. Forty-one fecal samples and corresponding diets were screened for Salmonella, Clostridium perfringens, Campylobacter jejuni, Staphylococcus aureus, Staphylococcus intermedius, and pathogenic (piliated) Escherichia coli by direct culture using standard procedures. The fecal material was also screened for coronavirus and parvovirus using electron microscopy. Thirty-five "normal" fecal samples were screened for all of the above mentioned microorganisms as a control. In addition, the fecal material was screened for E. coli verotoxins I and II and clostridial enterotoxins. A total of 61 Salmonella isolates were recovered from the 41 samples of feces and diet submitted for testing; 31 were recovered from the feces and 30 from the diet. Four Salmonella isolates were recovered from the normal fecal samples. Results obtained by PCR, plasmid profiles, antigenic analysis, and antibiogram profiles indicated that 16 of the 31 isolates recovered from the fecal material were the same strain as that recovered from the diet. 相似文献