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971.
NI Perrone-Bizzozero TV Isaacson GM Keidan C Eriqat KF Meiri DD Savage AM Allan 《Canadian Metallurgical Quarterly》1998,71(5):2104-2111
Consumption of moderate quantities of ethanol during pregnancy produces deficits in long-term potentiation in the hippocampal formation of adult offspring. Protein kinase C (PKC)-mediated phosphorylation of the presynaptic protein GAP-43 is critical for the induction of long-term potentiation. We tested the hypothesis that this system is affected in fetal alcohol-exposed (FAE) rats by measuring GAP-43 phosphorylation and PKC activity in the hippocampus of adult offspring of rat dams that had consumed one of three diets throughout gestation: (a) a 5% ethanol liquid diet, which produced a maternal blood ethanol concentration of 83 mg/dl (FAE); (b) an isocalorically equivalent 0% ethanol diet (pair-fed); or (c) lab chow ad libitum. Western blot analysis using specific antibodies to PKC-phosphorylated GAP-43 revealed that FAE rats had an approximately 50% reduction in the proportion of phosphorylated GAP-43. Similarly, we found that PKC-mediated incorporation of 32P into GAP-43 was reduced by 85% in hippocampal slices from FAE rats compared with both control groups. FAE animals also showed a 50% reduction in total hippocampal PKC activity, whereas the levels of six major PKC isozymes did not change in any of the diet groups. These results suggest that GAP-43 phosphorylation deficits in rats prenatally exposed to moderate levels of ethanol are not due to alterations in the expression of either the enzyme or substrate protein, but rather to a defect in kinase activation. 相似文献
972.
S. Griep B. Khare R. Lemme U. Papenberg D. Schmitt-Landsiedel W. Maly D. M. H. Walker J. Winnerl T. Zettler 《Quality and Reliability Engineering International》1994,10(4):297-302
In modern VLSI processes, increasing process complexity has resulted in an exponential rise in the costs of thorough failure analysis. In this paper, we present a defect simulation-based failure analysis methodology, which can be used to significantly reduce both costs and turn-around time for failure analyses. The methodology is based on the ability to generate a defect dictionary, which can relate defect characteristics to some easily measurable symptoms of defect occurrence. 相似文献
973.
AJ Watson PH Watson D Warnes SK Walker DT Armstrong RF Seamark 《Canadian Metallurgical Quarterly》1994,50(4):715-724
The roles of medium composition, serum source, embryo coculture, and culture under low O2 conditions on the development of in vitro-matured and in vitro-fertilized (IVMF) ovine zygotes were investigated in three separate experiments. In the first experiment, the proportion of cocultured IVMF zygotes developing to the blastocyst stage was significantly higher (38.0% vs. 3.5%; p < 0.05) than that of non-cocultured zygotes treated within three embryo culture media (TCM-199 + 10% fetal bovine serum [FBS]; bicarbonate-buffered, glucose-free synthetic oviduct fluid medium [mod-SOFM] + 10% FBS; and bicarbonate-buffered BSA-free Tyrode's salt solution [mod-TALP] + 10% FBS) under a 5% CO2 atmosphere in air. In a second experiment, a significantly higher (p < 0.05) proportion of cocultured zygotes placed in TCM-199 medium survived to the blastocyst stage (37.4% blastocysts vs. 23.4% in mod-SOFM). No significant effect of serum (FBS vs. human serum [HS]) was observed on embryonic development, but coculture was confirmed to exert a significant influence on development to the blastocyst stage. In the final experiment, survival of the embryo under a reduced oxygen (5% CO2:5% O2:90% N2) atmosphere was investigated. In contrast to results in the initial experiments, embryonic survival was significantly higher (p < 0.05) in the non-cocultured treatment groups (21.9% blastocysts vs. 0.4% for cocultured zygotes). Serum source also had a significant (p < 0.05) influence upon the development of non-cocultured zygotes: 32.3% of zygotes cultured with HS progressed to the blastocyst stage vs. 11.5% of zygotes cultured in FBS-supplemented medium. These results have characterized two distinct culture environments, each capable of supporting the development of high frequencies of unselected IVMF zygotes to the blastocyst stage in vitro. 相似文献
974.
In this paper, we conduct a system performance evaluation of code division multiple access communications over multimode optical fiber channels. More specifically, we complete the task started in Part I of this paper. In our system evaluation, we consider a collection of independent users sharing a common multimode optical fiber channel, which obey a binomial channel access and utilization model. Under this model, the bit error probability at the ith receiver is calculated as a function of the peak receive signal-to-noise ratio; where the signal-to-noise ratio is a function of the number of active users, the bit energy over “white” noise spectral density, and the percentage time users are active. We also make a comparison of the performance of this system with that obtained for an ideal channel 相似文献
975.
Pediatric patients with recurrent abdominal pain (RAP) were compared with patients with peptic disease, patients with emotional disorders, and well children with regard to (1) emotional and somatic symptoms and (2) theoretically derived variables, including negative life events, competence, family functioning, and the modeling and encouragement of illness behavior. RAP patients had levels of emotional distress and somatic complaints higher than those of well children and lower than those of psychiatric patients, but not different from those of patients with peptic disease. RAP patients had fewer negative life events, better family functioning, and higher competence than children with emotional disorders. In comparison with well children and psychiatric patients, both RAP and peptic disease patients had a higher incidence of illness in other family members and perceived greater parental encouragement of illness behavior for abdominal symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
976.
F Scolari GM Ghiggeri G Casari A Amoroso D Puzzer GL Caridi B Valzorio R Tardanico V Vizzardi S Savoldi BF Viola N Bossini E Prati R Gusmano R Maiorca 《Canadian Metallurgical Quarterly》1998,13(10):2536-2546
BACKGROUND: The nephronophthisis-medullary cystic disease (NPH/MCD) complex represents a heterogeneous group of hereditary tubulointerstitial nephritis. The most common variant is juvenile recessive NPH, for which a gene locus (NPH1) has been mapped on chromosome 2q13. MCD is a less common dominant condition usually recognized later in life, which resembles NPH in many aspects, still presenting remarkable clinical differences. Nothing is known about the chromosome locus of MCD. METHODS: Five MCD families were studied. Diagnosis was made by inference from family history, type of inheritance, clinical signs and histology. Multipoint linkage analysis was performed by markers D2S293, D2S340 and D2S160 spanning the entire NPH1 locus. RESULTS: Diagnosis of MCD was made in 28 affected members (16 males; 12 females), belonging to five families. Histological diagnosis was available in 10 patients; clinical diagnosis in 11; seven deceased relatives had diagnosis of chronic nephritis. The age at diagnosis ranged from 8 to 65 years. Renal medullary cysts were found in a minority of patients. In family 1, the disease was associated with hyperuricaemia and gouty arthritis. Progression of renal disease presented intra- and extra-family variability with members of the same family showing mild elevation of creatinine or terminal renal failure. The NPH1 locus associated to recessive NPH was excluded from linkage to the dominant MCD. CONCLUSIONS: MCD might be more common than previously assumed. Variability in clinical presentation and absence of histopathological hallmarks contribute to make the diagnosis uncommon. The most remarkable clinical difference with NPH is the age of onset in some kindreds and a delayed progression towards renal failure. The exclusion of linkage to the NPH1 locus suggests the existence of an MCD responsible locus, still to be mapped. 相似文献
977.
978.
This paper presents the experience of using microcomputers in the teaching of mathematics to undergraduates at Paisley College of Technology. The production of software for use by students has been a sizeable undertaking and the paper presents an account of the software development programme whose first stage was a formative and experimental period on which was based the specification of the software developed in the second stage. The definition and development of software tools for interactive programs to be used in mathematics teaching has been found to be of prime importance in producing the required software in a relatively efficient manner. 相似文献
979.
Several new compounds based on the ionic ferromagnet Rb2CrCl4 but with Br or I substituting for Cl have been prepared in powder and single crystal form. The compounds have been characterised by chemical and X-ray analysis. The ordering of the anions within the K2NiF4 type structure is discussed. 相似文献
980.
Walker Watson F. Tseng Fung-I Sarkar Tapan K. Cross John 《Geoscience and Remote Sensing, IEEE Transactions on》1983,(4):446-454
The energy spectrum [X2(f)] of a ?windowed sample? of an unmodulated RF carrier will generally exhibit a peak value at or near the carrier frequency. The location of this peak is frequently used in signal analysis as an estimate of the true carrier frequency. This paper investigates the error in such estimates in cases where the signal arrives in the presence of ?broad-band? additive noise and shows that the error is due to both the added noise and spectral ?leakage? effects. Both these error mechanisms are affected by window duration and window shape. This paper proceeds further to pose two optimization criteria for the selection of a ?best window? shape for the minimization of estimation error. The two criteria are related to two differing views of prior un-certainty about the actual carrier frequency. These criteria accordingly provide different, but similar forms for the optimum window. Moreover, in worsening signal-to-noise conditions, both forms of optimum window tend to a rectangular shape. 相似文献