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81.
We studied mechanical deformations induced when an insulating material was subjected to a gradual increase in a direct‐current electric field. Poly(ethylene terephthalate) film was studied with an optical technique, which was nondestructive and involved no physical contact. The experimental results indicated that the level of the induced mechanical deformation depended on the strength of the applied electric stress, the linear dimensions of the area under study, and the thickness of the film. When the studied area was relatively small, the level of the mechanical deformation seemed to be more important. The relationship between the induced mechanical deformation and the electric conduction phenomenon was also examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2313–2321, 2004 相似文献
82.
Prieto G. Velez M. Arrinda A. Gil U. Guerra D. de la Vega D. 《Broadcasting, IEEE Transactions on》2007,53(2):553-559
This paper presents an up to date study on external noise levels in the medium wave band based on field trials carried out in Spain and Mexico during years 2004 and 2005 respectively. External noise levels predicted by the ITU-R P.372 recommendation are based on measurements carried out more than 30 years ago and no updated results for the medium wave band have been published in this time. An increment on these noise levels have been measured, which leads to a significant impact on the minimum usable field strength requirements for the broadcasting systems used in this frequency band, such as the new Digital Radio Mondiale (DRM) and In-Band/On-Channel (IBOC) systems 相似文献
83.
84.
A. Vega L.C. Balbs J. Dorantes-Dvila G.M. Pastor 《Computational Materials Science》1994,2(3-4):463-467
The magnetic properties of FeN clusters (N = 1,9,15) embedded in non-magnetic and anti-ferromagnetic matrices (e.g., V, Cr) are calculated self-consistently by solving a realistic spd-band model Hamiltonian including intra-atomic Coulomb interactions in the unrestricted Hartree-Fock approximation. Our results are compared with those obtained for free FeN clusters and for the Fe, V and Cr solids. The role of the structural and chemical local environment on cluster magnetic properties is analyzed. Some of the implications of the present study for magnetic alloys and ferromagnetic clusters on surfaces are also briefly discussed. 相似文献
85.
The authors propose a method of phalloplasty with a full-thickness flap on the vasculo-nervous pedicle taken from the femur. The method of raising such a flap and the technique of its displacement to the area of the pubic articulation if described. This method of phalloplasty was used in 10 patients aged 19-36 years. In all of them full taking of the transplant was noted. Good cosmetic and functional results were obtained. 相似文献
86.
JM Saavedra JN Rodríguez D Vega L Pascual A Fernández-Jurado D Prados 《Canadian Metallurgical Quarterly》1998,16(6):285-286
A case report of a mandibular central incisor with two root canals and two separate apical foramina is presented. The tooth showed inadequate endodontic treatment and a periapical radiolucent lesion. The lesion healed following endodontic retreatment and proper obturation of both root canals. 相似文献
87.
W Apt X Aguilera F Vega H Alcaíno I Zulantay P Apt V González C Retamal J Rodríguez J Sandoval 《Canadian Metallurgical Quarterly》1993,115(5):405-414
This study sought to estimate for the first time the prevalence of fascioliasis among the rural population in the Chilean provinces of Curico, Talca, and Linares, while also determining the disease's prevalence among horses and wild rabbits in Curico and Talca and among pigs in Talca. From January 1986 to December 1990 a randomly selected sample of 5,861 persons in the three provinces was given intradermal, complement-fixation, double-diffusion, and immunoelectrophoresis tests to detect antibody to Fasciola hepatica. In addition, the ELISA test was used in Talca and Linares. Fecal specimens from horses and pigs were inspected for eggs, and the liver and bile ducts of rabbits were examined histopathologically. The overall prevalence of infection among the human subjects was 0.70%, with rates of 0.6% in Curico, 0.75% in Talca, and 0.71% in Linares. The prevalences of infection in horses, rabbits, and pigs were 13.5%, 6.1%, and 20.6%, respectively. It is estimated that some 2,000 people are infected in the study area. It is recommended that rabbits be taken into account in all control programs for this zoonosis. 相似文献
88.
1. Streptozotocin-induced diabetes produced significant changes on the drug metabolizing enzyme machinery of rat kidney microsomes. 2. It reduced the cytochrome P-450 content by 30%, this effect being reversed by insulin therapy. 3. Total androstenedione oxidative metabolism was increased 2.5-fold and insulin treatment partially antagonized this activation. 4. Total testosterone hydroxylase activities were not modified by diabetes nor by insulin but the formation of 2 alpha OH testosterone and 6 beta OH testosterone were distinct in diabetes or insulin treated diabetic rats. 5. Only UDP-glucuronyltransferase activity for PNP was found in kidney microsomes. Diabetes determined a lower UDPGT substrate efficiency not reversed by insulin therapy. 相似文献
89.
An epidemiologic case-control study to ascertain the determinants of low birthweight was carried out in Santiago, Chile, from January to December 1989. The cases were defined as livebirths < 2500 g. The controls were livebirths > or = 2500 g of birthweight. All cases and a random sample (1:1) of controls were selected among 8,254 singleton births occurring at the El Salvador Hospital in the Eastern area of Santiago. These deliveries represented 50% of institutional deliveries in the area. Home deliveries (2%) and private hospital deliveries were not included in the study. Information was obtained from hospital medical records by six trained medical students. Some information could not be obtained from the hospital medical records. Thus the second step in data collection was the tracking of all the selected subjects to their referring neighborhood health centers. For the analysis, the data were divided into 3 case (outcome) categories: 453 subjects were the total case group. From these, 153 were the IUGR case group and 300 were the LBW preterm case group. The general control group consisted of 605 normal birthweight infants. 565 were the IUGR control group and 40 were the preterm control group. A total of 25 risk factors showed a significant crude odds ratio for at least one of the groups. In the multivariate logistic regression analysis eight variables: No. of pregnancies, previous adverse outcomes, previous LBW, pregnancy maternal weight, No. of visits, month of first prenatal care visit, maternal smoking and intrahepatic cholestasis of pregnancy, were significantly associated with LBW after adjustment by confounding. Eight risk factors: IUGR in previous pregnancies, Previous adverse outcome, Maternal smoking, intrahepatic cholestasis, maternal pregnancy weight, maternal height, month first prenatal visit, No. of visit, were significant to IUGR. Only two variables: pregnancy weight, divorced mother, were significantly associated with low birth weight in the preterm group. The most relevant risk factors were included in stepwise logistic regression models carried out for the outcome LBW for the general group, term group and preterm group, in order to adjust by confounding. Adjusted odds ratios were then obtained. Prenatal care related factors and maternal adverse obstetric factors were at higher significance for LBW in the general and IUGR groups. Only nutritional factors were related to LBW in preterm group. Women who delivered a LBW or IUGR infant were more likely to have fewer pregnancies, a history of previous LBW, lower prepregnancy weight and lower gestational weight gain. ICP was associated with an elevated risk of LBW that was independent of gestational age. 相似文献
90.
H Hauser JH Dyer A Nandy MA Vega M Werder E Bieliauskaite FE Weber S Compassi A Gemperli D Boffelli E Wehrli G Schulthess MC Phillips 《Canadian Metallurgical Quarterly》1998,37(51):17843-17850
Here we show that scavenger receptor class B type I is present in the small-intestine brush border membrane where it facilitates the uptake of dietary cholesterol from either bile salt micelles or phospholipid vesicles. This receptor can also function as a port for several additional classes of lipids, including cholesteryl esters, triacylglycerols, and phospholipids. It is the first receptor demonstrated to be involved in the absorption of dietary lipids in the intestine. In liver and steroidogenic tissues, the physiological ligand of this receptor is high-density lipoprotein. We show that binding of high-density lipoprotein and apolipoprotein A-I to the brush border membrane-resident receptor inhibits uptake of cholesterol (sterol) into the brush border membrane from lipid donor particles. This finding lends further support to the conclusion that scavenger receptor BI catalyzes intestinal cholesterol uptake. Our findings suggest new therapeutic approaches for limiting the absorption of dietary cholesterol and reducing hypercholesterolemia and the risk of atherosclerosis. 相似文献