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Biomedical subjects

H Conway

Publications and source records attributed to H Conway.

At least 19 recordsLinked to original sources
PubMed2002

Switch of flow direction in an Antarctic ice stream.

Fast-flowing ice streams transport ice from the interior of West Antarctica to the ocean, and fluctuations in their activity control the mass balance of the ice sheet. The mass balance of the Ross Sea sector of the West Antarctic ice sheet is now positive--that is, it is growing--mainly because one of the ice streams (ice stream C) slowed down about 150 years ago. Here we present evidence from both surface measurements and remote sensing that demonstrates the highly dynamic nature of the Ross drainage system. We show that the flow in an area that once discharged into ice stream C has changed direction, now draining into the Whillans ice stream (formerly ice stream B). This switch in flow direction is a result of continuing thinning of the Whillans ice stream and recent thickening of ice stream C. Further abrupt reorganization of the activity and configuration of the ice streams over short timescales is to be expected in the future as the surface topography of the ice sheet responds to the combined effects of internal dynamics and long-term climate change. We suggest that caution is needed when using observations of short-term mass changes to draw conclusions about the large-scale mass balance of the ice sheet.

Journal Article↗
PubMed1999

Past and Future Grounding-Line Retreat of the West Antarctic Ice Sheet.

The history of deglaciation of the West Antarctic Ice Sheet (WAIS) gives clues about its future. Southward grounding-line migration was dated past three locations in the Ross Sea Embayment. Results indicate that most recession occurred during the middle to late Holocene in the absence of substantial sea level or climate forcing. Current grounding-line retreat may reflect ongoing ice recession that has been under way since the early Holocene. If so, the WAIS could continue to retreat even in the absence of further external forcing.

Journal Article↗
PubMed1994

Protein kinase C activity is reduced in epidermal cells from energy-restricted SENCAR mice.

Female SENCAR mice were pre-fed a control or 40% energy-restricted (ER) diet with energy removed from fat and carbohydrate, or a control, balanced high fat (BHF, with similar energy from fat and carbohydrate), 35% energy restricted from fat (HCR) or 35% energy restricted from carbohydrate (HFR) diet. Epidermal cells were isolated by trypsin digestion for measurement of protein kinase C (PKC) activity, lipid composition or lipid metabolism. Dietary restriction of fat or carbohydrate energy (HFR or HCR group) reduced particulate PKC activity in epidermal cells compared with cells from control mice. The ratio of soluble particulate PKC activity was higher in epidermal cells from mice fed the HCR diet compared with those fed the HFR diet. Diet did not affect soluble PKC activity. Inositol accumulation was measured in the water- or lipid-soluble fractions of prelabeled ([3H]inositol) epidermal cells following a 1-h incubation in media with LiCl. Phosphatidylinositol, inositol biphosphate and inositol triphosphate fractions were more heavily labeled in cells from mice fed the ER diet. Energy restriction did not modify epidermal total lipid or phospholipid composition, but 1,2-diacylglycerol levels were elevated in relation to cell number in epidermal cells from mice fed the ER diet. These data suggest that dietary energy restriction modified PKC activity through a pathway other than alteration in membrane lipid composition or inositol lipid metabolism.

Animals↗
PubMed1993

The Occupational Safety and Health Administration's 1990-1991 survey of occupational medical surveillance prevalence and type of current practices.

For all industry divisions, the likelihood that an establishment will have a medical surveillance program increases directly with size of establishment. Among establishments with 1 to 19 employees, only 4% have medical surveillance programs whereas 56% of establishments that employed 250 or more employees had such programs. The most common time to administer medical surveillance is preemployment. The second most common time to conduct medical surveillance is at periodic intervals. The most common component of medical surveillance programs is a general physical examination. This component of medical surveillance is also the most common element of preemployment surveillance, preplacement surveillance, periodic surveillance, preexit examinations, and surveillance for respirator users. Among the group of Phase II establishments, audiometric testing was the most common periodic test identified. Musculoskeletal testing is performed by 45% of firms administering preplacement examinations and by 38% of firms with preemployment examinations. Across all industry divisions, 14% of establishments that have a medical surveillance program also perform biologic monitoring of some employees.

Environmental Monitoring↗
PubMed1993

The purposes of occupational medical surveillance in US industry and related health findings.

The primary purpose for implementing medical surveillance is to protect the general health and fitness of all employees. The next most frequent purpose of medical surveillance programs is to determine whether employees have the physical capability to perform their jobs (ie, surveillance to establish "fitness for duty"). The most commonly reported uses of medical surveillance data for establishments across all industry divisions were to implement or change work practices, to implement or change administrative control programs, to modify training programs, and to change personal protective equipment. Eighteen percent of establishments in all size classes and industries that have medical surveillance programs have identified adverse health effects among employees. The health effects most commonly identified by the medical surveillance programs were repetitive trauma, hearing loss, and skin disorders. Programs designed to detect hearing loss and cumulative trauma disorders, are in fact, finding these adverse effects. Among employees actually receiving periodic medical surveillance tests (6 million), 5% were found to have an abnormal test result.

Humans↗
PubMed1993

Effects of occupational medical surveillance programs as perceived by respondents to the Occupational Safety and Health Administration's 1990-1991 survey.

Among all establishments perceiving a change as a result of their medical surveillance program, 43% of those employing 250 or more employees did so; for the smallest establishments, this figure drops to 7%. The changes most often perceived, regardless of size class of establishment or industry division, were in employee relations, injury rates, and insurance costs. Establishments with the most comprehensive risk reduction strategies were most likely to attribute benefits to their medical surveillance programs. Benefits of medical surveillance perceived by the Phase II respondents include reduced costs, early detection of medical problems, increased productivity, and a reduced injury or illness rate. Most firms have no systematic method or procedures for evaluating the effectiveness of their medical surveillance programs.

Humans↗
PubMed1976

Emergency medical care.

A survey carried out over five periods between 1973 and 1975 to study the mode of referral of emergency medical patients to a district general hospital showed that, out of a total of 2511 patients, 51% referred themselves, 40-8% were referred by general practitioners, and only 4-7% by doctors employed by the emergency treatment service. Of the 1720 patients admitted to the medical wards, 50-9% were referred by general practitioners and 37-3% were self-referred while the corresponding figures for the 791 not admitted were 19% and 80-7% respectively. Two-thirds of the self-referred patients came from their own homes, usually by ambulance ordered by a "999" emergency call. The figures were similar in each of the five periods.

Emergency Medical Services↗