STRESS INTENSITY FACTORS AND WEIGHT FUNCTIONS FOR SEMI-ELLIPTICAL SURFACE CRACKS IN FINITE-THICKNESS PLATES UNDER TWO-DIMENSIONAL STRESS DISTRIBUTION

Abstract— A Fourier series approach is proposed to calculate stress intensity factors using weight functions for semi-elliptical surface cracks in flat plates subjected to two-dimensional stress distributions. The weight functions were derived from reference stress intensity factors obtained by three-dimensional finite element analyses. The close form weight functions derived are suitable for the calculation of stress intensity factors for semi-elliptical surface cracks in flat plates under two-dimensional stress distributions with the crack aspect ratio in the range of 0.1 ≤ a/c ≤ 1 and relative depth in the range of 0 ≤ a/t ≤ 0.8. Solutions were verified using several two-dimensional non-linear stress distributions; the maximum difference being 6%.     

Consequences of the 1979 Three Mile Island accident continued: further comment

The development of multimedia image review stations offers the cardiologist the ability to review multiple image sets in a single setting rather than moving from one review station to another. To accomplish this goal there are three essential barriers: 1) memory requirements for digital images; 2) standardization of data format; and 3) practical user interfaces. Image compression algorithms can be used to overcome the digital barrier; however, these must be used cautiously so as to not adversely affect image quality. The lack of standardization is being addressed by the implementation of the Digital Communication in Medicine (DICOM) standard, and practical user interfaces are being developed every day with the widespread implementation of World Wide Web technology. These solutions will allow the clinician to review all of a patient's image data in one location, such as in the office, on the nursing unit, or at home.     

Electronic transport in a type-II GaInAsSb/p-InAs heterojunction with different doping levels of the solid solution

Galvanomagnetic phenomena and photoconductivity in broken-gap type-II GaInAsSb/p-InAs heterojunctions with different levels of doping of the solid solution with donor (Te) or acceptor (Zn) impurities have been investigated. It has been determined that in such structures an electronic channel, which determines the galvanomagnetic effects in a wide range of doping levels, is present at the heterojunction. A sharp decrease of the Hall mobility was observed in the experimental heterostructures with a high level of doping of the epitaxial layer with an acceptor impurity. The observed effect is due to exhaustion of the electronic channel as a result of carrier localization in potential wells at the heterojunction. Fiz. Tekh. Poluprovodn. 31, 897–901 (August 1997)     

No involvement of APC gene mutations in ulcerative colitis-associated rat colon carcinogenesis induced by 1-hydroxyanthraquinone and methylazoxymethanol acetate

In 1992, 1531 women aging 25-45 years from 5 urban and rural regions were interviewed about infertility and subfecundity within the German part of a study by the European community. 1248 of them had a positive reproductive history with 3018 pregnancies. 400 (= 13.25%) occurred during contraception. This affected 296 women (= 19.6% of all women). Smoking seems to have a promotion effect. The risk of ectopic pregnancies seems to be higher in contraceptive users. The highest fetal loss was found in women using an IUD. There were no differences in the course and outcome of pregnancy between users and nonusers of contraceptives. About 40% of the women in the corresponding group reported an irregular application of the contraceptive technique.     

Patterning of the chick forebrain anlage by the prechordal plate

We analysed the role of the prechordal plate in forebrain development of chick embryos in vivo. After transplantation to uncommitted ectoderm a prechordal plate induces an ectopic, dorsoventrally patterned, forebrain-like vesicle. Grafting laterally under the anterior neural plate causes ventralization of the lateral side of the forebrain, as indicated by a second expression domain of the homeobox gene NKX2.1. Such a lateral ventralization cannot be induced by the secreted factor Sonic Hedgehog alone, as this is only able to distort the ventral forebrain medially. Removal of the prechordal plate does not reduce the rostrocaudal extent of the anterior neural tube, but leads to significant narrowing and cyclopia. Excision of the head process results in the caudal expansion of the NKX2.1 expression in the ventral part of the anterior neural tube, while PAX6 expression in the dorsal part remains unchanged. We suggest that there are three essential steps in early forebrain patterning, which culminate in the ventralization of the forebrain. First, anterior neuralization occurs at the primitive streak stage, when BMP-4-antagonizing factors emanate from the node and spread in a planar fashion to induce anterior neural ectoderm. Second, the anterior translocation of organizer-derived cells shifts the source of neuralizing factors anteriorly, where the relative concentration of BMP-4-antagonists is thus elevated, and the medial part of the prospective forebrain becomes competent to respond to ventralizing factors. Third, the forebrain anlage is ventralized by signals including Sonic Hedgehog, thereby creating a new identity, the prospective hypothalamus, which splits the eye anlage into two lateral domains.     

Squamous cell carcinoma of the prostate: case report and review of literature

Carcinoma of the prostate, that is adenocarcinoma, is one of the most common malignancies in the male with an estimated incidence for 1991 of 122,000 new cases. On the other hand, squamous cell carcinoma of the prostate, with a median incidence of .5%-1% of all prostatic malignancies, has a similar clinical presentation but differs in treatment response and prognosis. We herein present one case of this histological pattern and review the literature pertaining to it.