Experimental isotherms of HCl on H2O ice under stratospheric conditions: connections between bulk and interfacial thermodynamics.

The adsorption of HCl on the surface of H(2)O ice has been measured at temperatures and pressures relevant to the upper troposphere and lower stratosphere. The measured HCl surface coverage is found to be at least 100 times lower than currently assumed in models of chlorine catalyzed ozone destruction in cold regions of the upper atmosphere. Measurements were conducted in a closed system by simultaneous application of surface spectroscopy and gas phase mass spectrometry to fully characterize vapor/solid equilibrium. Surface adsorption is clearly distinguished from bulk liquid or solid phases. From 180 to 200 K, submonolayer adsorption of HCl is well described by a Bragg-Williams modified Langmuir model which includes the dissociation of HCl into H(+) and Cl(-) ions. Furthermore, adsorption is consistent with two distinct states on the ice substrate, one in which the ions only weakly adsorb on separate sites, and another where the ions adsorb as an H(+)-Cl(-) pair on a single site with adsorption energy comparable to the bulk trihydrate. The number of substrate H(2)O molecules per adsorption site is also consistent with the stoichiometry of bulk hydrates under these conditions. The ionic states exist in equilibrium, and the total adsorption energy is a function of the relative population of both states. These observations and model provide a quantitative connection between the thermodynamics of the bulk and interfacial phases of HCl/H(2)O, and represent a consistent physicochemical model of the equilibrium system.

Long-term exercise patterns and immune function in healthy older women. A report of preliminary findings.

The purpose of this study was to examine the relationship between active versus inactive lifestyle and immunocompetence in older women. A sample of 46 independently dwelling, ambulatory and mentally alert women 60-98 years was examined, 25 who rated themselves as 'active' and 21 who rated themselves as 'inactive'. Lymphocyte subpopulations were analyzed by flow cytometry using selected monoclonal antibodies. The self-reported active subjects (also validated by their current unsolicited participation in a formal exercise class) demonstrated significantly higher percent change in CD25 mitogen stimulated lymphocytes (P = 0.0335) than those who reported themselves to be sedentary.

Aerodynamic Particle Sizing versus Light Scattering Intensity Measurement as Methods for Real-Time Particle Sizing Coupled with Time-of-Flight Mass Spectrometry.

Measurement of scattered light intensity and aerodynamic particle sizing are two methods that have recently been coupled with time-of-flight mass spectrometry for real-time determination of aerosol particle size and composition. An aerosol analysis technique recently developed in our laboratory, aerosol time-of-flight mass spectrometry, offers a unique experimental platform to evaluate both of these sizing techniques. This paper presents a comparison of results obtained with these two methods.

Mini-Mental State Exam status of community-dwelling cognitively intact centenarians.

Mini-Mental State Exam (MMSE) scores for 247 community-dwelling, well-functioning individuals in their 60s (n = 88), in their 80s (n = 92), and 100 or older (n = 67) were compared to examine overall and component MMSE differences. The concomitant influences of visual or literacy deficits, gender, education, race, income, and activities of daily living on MMSE performance were analyzed. Mean MMSE scores of 27.8, 27.1, and 24.8, respectively, for the three cohorts were significantly different, even when all concomitant variables were controlled. After the concomitant variables were controlled, results indicated that there were no age group differences on five MMSE items: naming, repeating, listening and obeying, reading and obeying, and writing sentences. Participants with visual or literacy deficits scored 1.5 points lower than other participants, and displayed performance deficits in four items from the Read & Write MMSE division:naming, reading and obeying, writing sentences, and praxis. Education and gender were significant covariates for total and divisional MMSE scores.

The influences of cognitive resources on adaptation and old age.

In the Georgia Centenarian Study, cognitive resources were estimated by fluid and crystallized intelligence, acquisition and retrieval of new information, retrieval of familiar information, and problem-solving ability in community-dwelling and nondemented adults ranging from sixty to one hundred plus years of age. Five clusters of results were found: 1) cognitive performances were lower for the older cohorts; 2) when cognitive activities were dependent on everyday experiences, no age-related problem-solving decline was found; 3) physical health and mental health can significantly influence cognitive performances; 4) cognitive and personality factors can combine to account for a larger amount of adaptation variance than can be accounted for by either of the factors alone; and 5) individuals with a high level of intelligence and affect sustain their instrumental activities of daily living. Cognitive resources were an important contributor to successful adaptation for the oldest-old.

Iliotibial band friction syndrome in runners.

The iliotibial band friction syndrome is an overuse injury found in long-distance runners. It is characterized by pain on the outer aspect of the knee in close relation to the lateral femoral epicondyle. It is usually poorly localized, is aggravated by running long distances or excessive striding, and is more severe running downhill. It may be prevented by walking with a stiff knee. In a series of 100 consecutive knees, including 6 patients with the syndrome in both knees (age range, 19 to 48 years; average, 31 years), of which 73 were available for follow-up evaluation, only 30 patients were resolved on the initial regimen of a single injection of local steroid and reduction in the training program. Twenty-one patients had two injections and 8 patients required the third injection. The remaining 14 patients were placed on a regimen of total rest from running for 4 to 6 weeks. Nine patients returned to training and had no recurrence of pain. Five patients consented to surgery and returned to long-distance running between 2 and 7 weeks later. The syndrome apparently has a higher incidence in areas where long-distance running is the vogue, such as, South Africa, or where the climate is cool and running surfaces are slippery.

The treatment of iliotibial band friction syndrome.

Iliotibial band friction syndrome is a common cause of knee pain in long distance runners. The pain is caused by friction of the iliotibial band over the lateral epicondyle of the femur. Two hundred and twenty one cases were seen in a two year period. Tenderness over the lateral epicondyle associated with pain at 30 degrees of flexion on compressing the iliotibial band against the lateral epicondyle is diagnostic. Conservative treatment consisted of treating the cause, mostly training irregularities and the local inflammation mostly with steroid injections and rest. Nine cases failed to respond to conservative treatment and these were treated by surgical release of the posterior fibres of the iliotibial band.