Geophysical investigation of seepage beneath an earthen dam.

A hydrogeophysical survey is performed at small earthen dam that overlies a confined aquifer. The structure of the dam has not shown evidence of anomalous seepage internally or through the foundation prior to the survey. However, the surface topography is mounded in a localized zone 150 m downstream, and groundwater discharges from this zone periodically when the reservoir storage is maximum. We use self-potential and electrical resistivity tomography surveys with seismic refraction tomography to (1) determine what underlying hydrogeologic factors, if any, have contributed to the successful long-term operation of the dam without apparent indicators of anomalous seepage through its core and foundation; and (2) investigate the hydraulic connection between the reservoir and the seepage zone to determine whether there exists a potential for this success to be undermined. Geophysical data are informed by hydraulic and geotechnical borehole data. Seismic refraction tomography is performed to determine the geometry of the phreatic surface. The hydro-stratigraphy is mapped with the resistivity data and groundwater flow patterns are determined with self-potential data. A self-potential model is constructed to represent a perpendicular profile extending out from the maximum cross-section of the dam, and self-potential data are inverted to recover the groundwater velocity field. The groundwater flow pattern through the aquifer is controlled by the bedrock topography and a preferential flow pathway exists beneath the dam. It corresponds to a sandy-gravel layer connecting the reservoir to the downstream seepage zone.

Visual capacity and Prader-Willi syndrome.

PURPOSE: Prader-Willi syndrome (PWS) refers to a genetic disorder induced by an anomaly on chromosome 15 occurring with a frequency of one in 10,000 to 20,000. It is characterized by a unique set of features including infantile hypotonia, obesity in childhood, small hands and feet, hypogonadism, and mental retardation. Reported here are the results of ophthalmic examinations of persons with PWS, together with results from controls comparable in age, percentage of body fat, and intelligence. These data bear on the hypothesis that the ocular anomalies in PWS are unique to this syndrome. METHOD: A comprehensive investigation of PWS brought children and adults to Vanderbilt University for extended testing, which included an ophthalmic examination. Genetic analysis determined unequivocally the PWS diagnosis and identified subgroups-deletion and maternal disomy. A group of persons without PWS but generally comparable in age, body composition, and intelligence served as controls. RESULTS: Significant differences between the deletion and disomy subgroups were not found for the clinical ophthalmic measures. The incidence of anomalies in the combined PWS was similar to those reported in previous studies. A similar pattern was present in the control group except for myopia and stereopsis. An effect of genetic subgroup, however, was observed for random element stereopsis with the maternal disomy group having a greater degree of impairment. CONCLUSION: The overall similarity between the PWS and control groups on all measures except myopia and stereopsis suggest that many of the anomalies in PWS found in prior studies are due to factors inherent in a general dysfunctional population, rather than reflective of an ocular signature unique to PWS.

Evaluation of the effects of omega-3 fatty acid-containing diets on the inflammatory stage of wound healing in dogs.

OBJECTIVES: To ascertain the effects of dietary omega-3 (n-3) fatty acids on biochemical and histopathologic components of the inflammatory stage of wound healing. ANIMALS: 30 purpose-bred Beagles. PROCEDURE: Dogs were allotted to 5 groups of 6. Each group was fed a unique dietary fatty acid ratio of omega-6 to n-3--diet A, 5.3:1; diet B, 10.4:1; diet C, 24.1:1; diet D, 51.6:1; and diet E, 95.8:1. Dogs were fed once daily for 12 weeks, then biopsy specimens were taken from 4-day-old wounds of each dog and analyzed by gas chromatography-mass spectrometry for: prostaglandin E2 (PGE2) metabolites, and ratios of omega-6 to n-3 fatty acids, arachidonic acid (AA) to eicosapentaenoic acid (EPA), adrenic acid to docosahexaenoic acid, and PGE2 to prostaglandin E3 (PGE3) metabolites. RESULTS: Qualitative analysis was carried out on AA, EPA, adrenic acid, docosahexaenoic acid, and the major metabolite from the PGE2 and PGE3 pathway. These molecules were further quantified with respect to diet to determine significant differences. By analysis of the AA-to-EPA ratio, diet A was different from diets D and E and diets B and C were different from diet E (P < 0.05). By analysis of the PGE2-to-PGE3 metabolite ratio, diet A was different from diet E (P < 0.05). Though biochemical analysis indicated dietary dependence, histopathologic data indicated no significant difference with respect to diet groups. CONCLUSION: The biochemical component of the inflammatory stage of wound healing can be manipulated by diet. CLINICAL RELEVANCE: Omega-3 fatty acid-enriched diets can be used to control inflammation associated with dermatologic conditions.

Halo nevus or halo phenomenon? A study of 142 cases.

One hundred and forty-two (142) halo nevi were reviewed. For 66 cases the diagnosis of halo nevus was made both clinically and pathologically, and for 76 cases the diagnosis was based on histological grounds alone. The nevi were classified by type and by degree of atypia. Of the 142 nevi, all were compound, junctional, or intradermal nevi except for one case of a Spitz nevus and two cases that could not be further classified. For those with a clinicopathological diagnosis of halo nevus, 11% exhibited moderate atypia; 16% exhibited minimal atypia to only focally moderate atypia; 24% minimal atypia; and 49% exhibited no significant atypia. For those cases where the diagnosis was pathological only, there was also a broad spectrum of atypia identified, with 8% exhibiting focally severe or severe atypia. This study supports the concept that the halo nevus should not be regarded as a single clinicopathological entity, but rather that the halo phenomenon occurs in a wide spectrum of nevus types exhibiting a wide spectrum of histological atypia. The pathologist is therefore encouraged to classify halo nevi on the basis of the nevus cell population alone, using whatever classification normally utilized.

[Cost benefit analysis and ethics of prenatal diagnosis]. / Cost-benefit analyse og etik i forbindelse med fosterdiagnostik.

Cost-benefit analysis is a necessary part of the decision-making process concerning the introduction of DNA-analysis in antenatal diagnosis (and diagnosis of carrier status) of hereditary diseases. The problems involved which are of increasing significance given the rapid development in mapping of the human genome, are reviewed on the basis of the autosomal dominant polycystic kidney disease. Many problems exist, particularly of an ethical nature, when attempts are made to employ cost-benefit analysis in this field. This article describes some of these and suggests some solutions. The discussion is concentrated on the need to decide what should be done as regards the genetic diagnosis, why this should be done and how decisions should be made to do so. These questions are too important to be decided by only the medical profession. Many others, not only in the health sector, are involved both economically and ethically. The numerous new methods of analysis make it necessary to decide who is to assess the costs and benefits when the Danish health service allocares resources to this and to many other fields.

Comparisons among three articulation sampling procedures with preschool children.

The purpose of this study was to compare the articulatory responses of normally developing preschool children during three sampling procedures which were controlled for phonetic context. Thirty normally developing children (15 boys, 15 girls) aged 4:4 to 4:8 (years:months) served as subjects. The three test conditions were word test (stimuli consisting of multisyllabic meaningful words and word-strings), nonsense test (items consisting of multisyllabic nonsense utterances), and story-retell. Eight phonemes /t k l s f r tf f/ were tested in each of the three sampling conditions. The stimuli, elicited with pictures, were also controlled for syllable structure, canonical form, and semantic difficulty. Results showed no difference among the three sampling procedures for type and number of errors. Consistency of errors was presented and discussed. A significant sex difference, with boys making significantly more errors than girls, supported separation of articulation data by sex for 4-year-old children.