1,704 research outputs found

    Elasticity of demand for gasoline in the South Coast Air Basin

    Get PDF
    An analysis of California gasoline sales was made, using Box and Jenkins' linear time series methods, in an attempt to detect the change due to a 17% change in price. There was no detectable change within the 2% noise limit of the method. Thus, either the elasticity is less than 2 parts in 17, and/or the tools must be further refined to detect it

    Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest.

    Get PDF
    Leg muscle mass and strength are decreased during reduced activity and non-weight-bearing conditions such as bed rest (BR) and spaceflight. Supine treadmill exercise within lower body negative pressure (LBNPEX) provides full-body weight loading during BR and may prevent muscle deconditioning. We hypothesized that a 40-min interval exercise protocol performed against LBNPEX 6 days week(-1) would attenuate losses in leg lean mass (LLM), strength, and endurance during 6° head-down tilt BR, with similar benefits for men and women. Fifteen pairs of healthy monozygous twins (8 male and 7 female pairs) completed 30 days of BR with one sibling of each twin pair assigned randomly as the non-exercise control (CON) and the other twin as the exercise subject (EX). Before and after BR, LLM and isokinetic leg strength and endurance were measured. Mean knee and ankle extensor and flexor strength and endurance and LLM decreased from pre- to post-BR in the male CON subjects (P < 0.01), but knee extensor strength and endurance, ankle extensor strength, and LLM were maintained in the male EX subjects. In contrast, no pre- to post-BR changes were significant in the female subjects, either CON or EX, likely due to their lower pre-BR values. Importantly, the LBNPEX countermeasure prevents or attenuates declines in LLM as well as extensor leg strength and endurance. Individuals who are stronger, have higher levels of muscular endurance, and/or have greater LLM are likely to experience greater losses during BR than those who are less fit

    Care of HIV-infected adults at Baragwanath Hospital, Soweto

    Get PDF
    Part I. Clinical management and costs of outpatient careObjective. To provide a detailed breakdown of clinical presentations and management of outpatients with HIV. and associated costs, in order to inform clinical practice, health service planning and projections of the costs of HIV care in South AfricaSetting. The outpatient department of a public sector, academic hospital in Soweto, South AfricaDesign. A retrospective, descriptive study using a record review and a combination of direct and step-down costing of health service costs (1992 prices).Patients. All 179 patients with HIV seen at the outpatient department between 1989 and 1992.Results. The average age at presentation was 30 years for men and 29 years for women. The most common clinical presentations at first viSIT were lymphadenopathy, weight loss, peripheraJ neuropathy and tuberculosis. Many patients, however, were asymptomatic. Analysis of clinical presentations, investigations and drugs used indicated that at least 80% of patients could have been managed at primary care leveL The average cost per consultation was R112.03. Costs per patient and per visit increased with stage of disease. Most of the costs arose from variable costs, which are influenced by clinical management decisions. Laboratory investigations (30%), staff (21 %) and drugs (22%), especially for fungal, viral and tuberculosis infection, were the major contributors to costs.Conclusions. Given projected HIV infection rates and the associated, potentially enormous costs of care revealed by this study, clinicians and health service planners must identify and implement cost-effective approaches to investigating, treating and meeting other health care needs of HIV-infected people. Treatment of people with HIV at primary care outpatient services seems both possible and potentially more cost-effective than hospital-level care in South Africa Emphasis should be placed on building primary level capacity to take on this role effectively. Further studies are required to identify the costeffectiveness, not only of treating HIV-related conditions, but also of treating other diseases if just and adequately infonned decisions about rationing of care are required in view of resource constraints

    Twins Bed Rest Project: LBNP/Exercise Minimizes Changes in Lean Leg Mass, Strength and Endurance

    Get PDF
    Decreases in muscle strength and endurance frequently are observed in non-weightbearing conditions such as bed rest (BR), spaceflight or limb immobilization. Purpose: Ow purpose was to determine if supine treadmill exercise against simulated gravity, by application of lower body negative pressure (LBNP), prevents loss of lean leg mass, strength and endurance during 30 d of 6deg head-down bed rest (BR). Methods: Fifteen pairs of monozygous twins (8 male, 7 female pairs; 26+/-4 yrs; 170+/-12 cm; 62.6+/-11.3 kg; mean+/-SD) were subjects in the present study. One sibling of each pair of twins was randomly assigned to either an exercise (EX) or non-exercise (CON) group. The EX twin walked/jogged on a vertical treadmill within LBNP chamber 6 d/wk using a 40-min interval exercise protocol at 40-80% of pre-BR VO(sub 2peak). LBNP was adjusted individually for each subject such that footward force was between 1.0 and 1.2 times body weight (-53+/-5 mmHg LBNP). The CON twin performed no exercise during BR. Subjects performed isokinetic knee (60 and 120deg/s) and ankle (60deg/s) testing to assess strength and endurance (End) before and after BR. They also had their lean leg mass (L(sub mass)) evaluated by DEXA before and after BR. Results: Changes in peak torque (T(sub pk)) were smaller for flexion (flex) than for extension (ext) after BR and did not differ between groups. The CON group had larger decreases (P<0.05) in L(sub mass), knee and ankle ext T(sub pk), and knee ext End

    Upregulation of 8-Lipoxygenase in the Dermatitis of IκB-α-Deficient Mice

    Get PDF
    Neonatal mice deficient in IκB-α, an inhibitor of the ubiquitous transcription factor NF-κB, develop severe and widespread dermatitis shortly after birth. In humans, inflammatory skin disorders such as psoriasis are associated with accumulation in the skin of the unusual arachidonic acid metabolite 12R-hydroxyeicosatetraenoic acid (12R-HETE), a product of the enzyme 12R-lipoxygenase. To examine the etiology of the murine IκB-α-deficient skin phenotype, we investigated the expression of lipoxygenases and the metabolism of exogenous arachidonic acid in the skin. In the IκB-α-deficient animals, the major lipoxygenase metabolite was 8S-HETE, formed together with a minor amount of 12S-HETE; 12R-HETE synthesis was undetectable. Skin from the wild-type littermates formed 12S-HETE as the almost exclusive lipoxygenase metabolite. Upregulation of 8S-lipoxygenase (8-LOX) in IκB-α-deficient mice was confirmed at the transcriptional and translational level using ribonuclease protection assay and western analysis. In immunohistochemical studies, increased expression of 8-LOX was detected in the stratum granulosum of the epidermis. In the stratum granulosum, 8-LOX may be involved in the terminal differentiation of keratinocytes. Although mouse 8S-lipoxygenase and human 12R-lipoxygenase are not ortholog genes, we speculate that in mouse and humans the two different enzymes may fulfill equivalent functions in the progression of inflammatory dermatoses

    Supine Lower Body Negative Pressure Exercise Maintains Upright Exercise Capacity in Male Twins during 30 Days of Bed Rest

    Get PDF
    Exercise capacity is reduced following both short and long duration exposures to microgravity. We have shown previously that supine lower body negative pressure with exercise (LBNP(sub ex) maintains upright exercise capacity in men after 5d and 15d bed rest, as a simulation of microgravity. We hypothesized that LBNP(sub ex) would protect upright exercise capacity (VO2pk) and sprint performance in eight sets of identical male twins during a 30-d bed rest. Twins within each set were randomly assigned to either a control group (CON) who performed no exercise or to an exercise group (EX) who performed a 40-min interval (40-80% pre-BR VO2pk) LBNP(sub ex) (55+/-4 mmHg) exercise protocol, plus 5 min of resting LBNP, 6 d/wk. LBNP produced footward force equivalent to 1.0- 1.2 times body weight. Pre- and post-bed rest, subjects completed an upright graded exercise test to volitional fatigue and sprint test of 30.5 m. After bed rest, VO2pk was maintained in the EX subjects (-3+/-3%), but was significantly decreased in the CON subjects (-24+/-4%). Sprint time also was increased in the CON subjects (24+/-8%), but maintained in the EX group (8+/-2%). The performance of a supine, interval exercise protocol with LBNP maintains upright exercise capacity and sprint performance during 30 d of bed rest. This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long duration space flight

    Investigations of γ′, γ″ and δ precipitates in heat-treated Inconel 718 alloy fabricated by selective laser melting

    Get PDF
    Inconel 718 alloy samples were fabricated by selective laser melting (SLM). Microstructure and precipitation in solution-heat-treated- and double-aging-SLM-made Inconel 718 were studied by scanning and transmission electron microscopy. Electron microscope observations showed that disc-shaped and cuboidal γ″, and circular γ′ precipitates with an average size of 10–50 nm developed within cellular γ austenite matrix. The simulated, experimentally observed electron diffraction patterns, and dark-field imaging further revealed that the precipitation of three variants of γ″ in the γ matrix occurred. The coarser acicular γ″, and globular as well as plate-like δ phases precipitated at grain boundaries and also within the interior of austenite matrix. The morphology, distribution and crystallography of these precipitates and their formation mechanisms were analyzed and discussed
    • …
    corecore