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Full-Text Articles in Social and Behavioral Sciences

Enzyme Activity And Flexibility At Very Low Hydration, V Kurkal, R M. Daniel, John L. Finney, Moeava Tehei, R V. Dunn, Jeremy C. Smith Jan 2005

Enzyme Activity And Flexibility At Very Low Hydration, V Kurkal, R M. Daniel, John L. Finney, Moeava Tehei, R V. Dunn, Jeremy C. Smith

Faculty of Science, Medicine and Health - Papers: part A

Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. This raises the question of whether hydration-induced enzyme flexibility is important for activity. Here, to address this, picosecond dynamic neutron scattering experiments are performed on pig liver esterase powders at 0%, 3%, 12%, and 50% hydration by weight and at temperatures ranging from 120 to 300 K. At all temperatures and hydrations, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases, a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. The implication of these results …

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Replication Termination In Escherichia Coli: Structure And Anti-Helicase Activity Of The Tus-Ter Complex, Cameron Neylon, Andrew V. Kralicek, Thomas M. Hill, Nicholas E. Dixon Jan 2005

Replication Termination In Escherichia Coli: Structure And Anti-Helicase Activity Of The Tus-Ter Complex, Cameron Neylon, Andrew V. Kralicek, Thomas M. Hill, Nicholas E. Dixon

Faculty of Science, Medicine and Health - Papers: part A

The arrest of DNA replication in Escherichia coli is triggered by the encounter of a replisome with a Tus protein-Ter DNA complex. A replication fork can pass through a Tus-Ter complex when traveling in one direction but not the other, and the chromosomal Ter sites are oriented so replication forks can enter, but not exit, the terminus region. The Tus-Ter complex acts by blocking the action of the replicative DnaB helicase, but details of the mechanism are uncertain. One proposed mechanism involves a specific interaction between Tus-Ter and the helicase that prevents further DNA unwinding, while …

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Geomagnetic Activity Forcing Of The Northern Annular Mode Via The Stratosphere, Daniel Palamara, Edward Bryant Jan 2004

Geomagnetic Activity Forcing Of The Northern Annular Mode Via The Stratosphere, Daniel Palamara, Edward Bryant

Faculty of Science, Medicine and Health - Papers: part A

We consider various aspects of the link between solar-modulated geomagnetic activity and the Northern Annular Mode (NAM). Our results indicate that the geomagnetic forcing of atmospheric circulation in the Northern Hemisphere is temporally and seasonally restricted, modulated by the Quasi-Biennial Oscillation (QBO), and reliant on stratosphere-troposphere coupling. When the data are restricted to January values after 1965, for years in which the January QBO is eastwards, the correlation coefficient between the geomagnetic AA index and the NAM is 0.85. These results can account for many of the enigmatic features of Northern Hemisphere circulation.

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Can Motivational Signs Prompt Increases In Incidental Physical Activity In An Australian Health-Care Facility?, A L. Marshall, A E. Bauman, C Patch, J Wilson, J Chen Jan 2002

Can Motivational Signs Prompt Increases In Incidental Physical Activity In An Australian Health-Care Facility?, A L. Marshall, A E. Bauman, C Patch, J Wilson, J Chen

Faculty of Health and Behavioural Sciences - Papers (Archive)

This study aimed to evaluate whether a stairpromoting signed intervention could increase the use of the stairs over the elevator in a health-care facility. A time-series design was conducted over 12 weeks. Data were collected before, during and after displaying a signed intervention during weeks 4–5 and 8–9. Evaluation included anonymous counts recorded by an objective unobtrusive motion-sensing device of people entering the elevator or the stairs. Self-report data on stair use by hospital staff were also collected. Stair use significantly increased after the first intervention phase (P 0.02), but after the intervention was removed stair use decreased back towards …

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Physical Activity, Change In Blood Pressure And Predictors Of Mortality In Older South Africans - A 2-Year Follow-Up Study, Karen E. Charlton, Estelle V. Lambert, Judith Kreft Jan 1997

Physical Activity, Change In Blood Pressure And Predictors Of Mortality In Older South Africans - A 2-Year Follow-Up Study, Karen E. Charlton, Estelle V. Lambert, Judith Kreft

Faculty of Science, Medicine and Health - Papers: part A

Objective. A 2-year follow-up study of a cohort of 200 historically disadvantaged older South Africans was conducted to: (i) characterise current levels of habitual physical activity; (ii) relate physical activity to current risk factors for chronic disease; and (iii) identify risk factors associated with 2-year mortaJity. The baseline sample, drawn in 1993, was found to have a high prevalence of hypertension (71.7%). Research design. Retrospective cohort study. Methods. A baseline sample of 200 persons aged ;:;.. 65 years, resident in the Cape Peninsula, was randomly drawn by means of a two-stage cluster design. Baseline measurements included: anthropometry, waist/hip ratio, systolic …

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