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Biomedical subjects

D H Hill

Publications and source records attributed to D H Hill.

At least 19 recordsLinked to original sources
PubMed1997

Petrography and bulk chemistry of Martian orthopyroxenite ALH84001: implications for the origin of secondary carbonates.

New petrologic and bulk geochemical data for the SNC-related (Martian) meteorite ALH84001 suggest a relatively simple igneous history overprinted by complex shock and hydrothermal processes. ALH84001 is an igneous orthopyroxene cumulate containing penetrative shock deformation textures and a few percent secondary extraterrestrial carbonates. Rare earth element (REE) patterns for several splits of the meteorite reveal substantial heterogeneity in REE abundances and significant fractionation of the REEs between crushed and uncrushed domains within the meteorite. Complex zoning in carbonates indicates nonequilibrium processes were involved in their formation, suggesting that CO2-rich fluids of variable composition infiltrated the rock while on Mars. We interpret petrographic textures to be consistent with an inorganic origin for the carbonate involving dissolution-replacement reactions between CO2-charged fluids and feldspathic glass in the meteorite. Carbonate formation clearly postdated processes that last redistributed the REE in the meteorite.

Carbon Dioxide↗
PubMed1997

Adjusting for attrition in event-history analysis.

"This paper will investigate the issue of weighting for panel attrition in event-history models by comparing alternative treatments of sampling weights in a divorce model for members of the 1986 [U.S.] Survey of Income and Program Participation (SIPP). Three distinct weighting procedures are compared. These are based on (1) the initial selection probability weights; (2) the 1986 SIPP panel weights; and (3) the monthly attrition-adjusted weights. The paper also compares these weighted estimates with the estimates of a structural model in which attrition is treated as an error-correlated competing alternative to divorce." The results indicate that in many instances divorces in the SIPP end up being recorded as attrition.

Americas↗
PubMed1993

Metachronous colonic lymphomas complicating chronic ulcerative colitis.

The gastrointestinal tract is the most common extranodal site of primary non-Hodgkin's lymphoma. Of these, 10-15% occur in the large bowel. Colonic lymphoma is a recognized complication of inflammatory bowel disease, particularly ulcerative colitis and, less commonly, Crohn's disease. We describe a unique case of two metachronous primary lymphomas of the large bowel in a patient with chronic ulcerative colitis.

Colitis, Ulcerative↗
PubMed1993

Competing hazards with shared unmeasured risk factors.

"The present paper develops a generalization of the standard discrete-time competing hazards model that allows for the types of stochastic dependencies resulting from shared unmeasured risk factors. An empirical example is provided using the process by which young women form their first conjugal residential union, with married and unmarried cohabitation representing the competing alternatives. The results suggest considerable and significant similarity of the alternatives in terms of the unmeasurables. It is also shown that, as a result, the independence assumption leads to substantially biased estimates of the net marriage and net cohabitation survival functions." The data concern a cohort of white children born in Detroit, Michigan, in 1961 and their mothers, followed up to 1985.

Americas↗
PubMed1978

Arthroscopy of the knee.

Fiberoptics permit a minimally invasive direct inspection of the knee joint. Arthroscopy is indicated when no definitive clinical diagnosis can be made. An organized approach includes inspection of the suprapatellar pouch, the articular surfaces of the patella, the medial and lateral compartments of the knee and the intercondylar area. Common afflictions diagnosed by arthroscopy include chondromalacia, meniscal lesions, osteoarthritis, cruciate ligament injuries, chronic synovitis and loose bodies. Complications and morbidity are minimal.

Endoscopes↗
PubMed1977

Clinical, haematological and pathological studies in donkeys experimentally infected with Trypanosoma brucei.

Donkeys experimentally infected with Trypanosoma brucei showed dullness, weakness, fever, inappetence, conjunctivitis, tachycardia and polydyspnoea soon after detectable parasitaemia. The parasitaemia was generally low with transient high peaks except in the terminal stage when there was sustained high parasitaemia. A moderate anaemia was present as from the second week of infection but it was not progressive. There was a marked leucopoenia within 24 h of patent parasitaemia. Death occurred 2 to 2 1/2 months after infection and at necropsy there was severe emaciation as well as mild serous effusion. Histologically, there was a nonsuppurative encephalomyelitis, cranial neuritis, extensive haemosiderosis, hyperplasia of follicles in lymph nodes and spleen and giant cell reaction in lymph nodes. Trypanosomes were present in the cerebrospinal fluid, the eye and serous effusions. These observations are similar to those previously reported in other animals infected with T. brucei.

Animals↗
PubMed1975

Oral fibroma in a captive python.

A massive growth in the lower jaw of an Indian python (Python molurus) was diagnosed from biopsy samples as a fibroma. Moderately satisfactory treatment was achieved by surgical excision.

Animals↗