Controls on Cyclic Formation of Quaternary Early Diagenetic Dolomite

The origin of sedimentary dolomite and the factors that control its formation within the geological record remain speculative. In most models, dolomite formation is linked to evaporative conditions, high water temperature, increasing Mg/Ca ratio, increasing alkalinity, and high amounts of biomass. Here we challenge these archetypal views, by documenting a case example of Quaternary dolomite which formed in Lake Van at constantly low temperature (<4°C) and without direct control of the latter conditions. Dolomite occurs within highstand sediments related to suborbital climate variability (Dansgaard‐Oeschger cycles). We propose that dolomite precipitation is a product of a microbially influenced process, triggered by ecological stress, resulting from reventilation of the water‐sediment interface. Independently from the validity of this hypothesis, our results call for a reevaluation of the paleoenvironmental conditions often invoked for early diagenetic dolomite‐rich intervals within sedimentary sequences and for caution when interpreting time series of subrecent lacustrine carbonates

TRUCKSIM - A Log Truck Performance Simulator

Forestry transport expenditures in Australia include both the costs of owning and operating logtrucks, and the costs of constructing and maintaining many kilometres of logging roads. Therefore,improving transport efficiency requires consideration of both road and truck related factors. However, analysis of these factors involves many complex interacting variables. A computer simulation model, TRUCKSIM, has been developed to assist in these analyses by predicting the effects of both road and alternative vehicle specification on transport performance. A description of the model and it's supporting programs is presented, together with a discussion of it's limitations and examples of it's use in evaluating alternative truck and road specifications

A comparison between conventional and holistic exercise interventions on physiological function in the elderly

Aging is characterised by a decline in physiological function. The rate of this decline can depend on certain lifestyle factors, genetics, and the environment. Although life expectancy is slowly increasing, there is a need to reduce the time spent in debilitated, and non-independent states by elderly individuals. Preventive measures need to be implemented to reduce dependency and improve the quality of life for elderly individuals. One such preventive and remedial measure is the use of exercise and physical activity. Because limited exercise prescription exists for the elderly population, there is a need to determine the effectiveness of exercise interventions that are more desirable for elderly individuals. Hence, the purpose of this pilot study was to implement and compare two types of exercise interventions, a holistic exercise intervention (Range of Motion Dance method or ROM) and a Conventional Exercise intervention commonly performed in the community by aged individuals. Forty-three elderly individuals over 65-years of age were randomly allocated to the two intervention groups and a control group. The exercise interventions were performed for 10-weeks and included baseline and post-intervention testing. The groups were compared using Analysis of Covariance on the following variables; muscular strength (grip strength, isokinetic knee flexion and extension); postural stability (Berg Balance Scale, and Center of Pressure): and functionality (Timed \u27up\u27 and \u27go\u27 and Physical Performance Test). T-tests were performed to compare the two intervention groups on attrition and compliance. The Conventional Exercise and the ROM exercise groups generally showed similar results on all physiological parameters when compared to each other. However, some statistically significant differences were observed between the intervention groups and the control group for isokinetic knee flexor and extensor strength, grip strength and the Physical Performance Test. Mean differences between post-intervention and baseline results for knee extensor and flexor strength measures ranged between 0.97 to 5.78 Newton meters for the Conventional Exercise group; -6.00 to 5.73 Newton meters for\u27 the ROM group and; 8.74 to 5.36 Newton meters for the Control group. Both intervention groups showed improvement of approximately 1.5 units for the Physical Performance Test, while the Control group showed no change. No statistically significant differences were found between the groups for any balance measures or for the Timed Up and Go . The two interventions groups showed similar average attendance rates, with 85.4% of sessions performed by the Conventional Exercise group and 88.9% of sessions performed by the ROM group. The performance of low-intensity exercise intervention, of either a conventional or holistic nature, may provide positive physiological benefits for elderly participants, such as maintaining or improving knee flexor and extensor strength and enhancing functionality. Thus this study provides evidence that low-intensity exercise interventions in the short term can cause physiological change while at the same time maintaining relatively high rates of participation

The Effect of Zonally Asymmetric Ozone Heating on the Northern Hemisphere Winter Polar Stratosphere

[1] Previous modeling studies have found significant differences in winter extratropical stratospheric temperatures depending on the presence or absence of zonally asymmetric ozone heating (ZAOH), yet the physical mechanism causing these differences has not been fully explained. The present study describes the effect of ZAOH on the dynamics of the Northern Hemisphere extratropical stratosphere using an ensemble of free-running atmospheric general circulation model simulations over the 1 December - 31 March period. We find that the simulations including ZAOH produce a significantly warmer and weaker stratospheric polar vortex in mid-February due to more frequent major stratospheric sudden warmings compared to the simulations using only zonal mean ozone heating. This is due to regions of enhanced Eliassen-Palm flux convergence found in the region between 40°N–70°N latitude and 10–0.05 hPa. These results are consistent with changes in the propagation of planetary waves in the presence of ZAOH predicted by an ozone-modified refractive index

Absolute continuity and spectral concentration for slowly decaying potentials

We consider the spectral function $\rho(\mu)$ $(\mu \geq 0)$ for the Sturm-Liouville equation $y^{''}+(\lambda-q)y =0$ on $[0,\infty)$ with the boundary condition $y(0)=0$ and where $q$ has slow decay $O(x^{-\alpha})$ $(a>0)$ as $x\to \infty$. We develop our previous methods of locating spectral concentration for $q$ with rapid exponential decay (JCAM 81 (1997) 333-348) to deal with the new theoretical and computational complexities which arise for slow decay

Extensions of a New Algorithm for the Numerical Solution of Linear Differential Systems on an Infinite Interval

This paper is part of a series of papers in which the asymptotic theory and appropriate symbolic computer code are developed to compute the asymptotic expansion of the solution of an n-th order ordinary differential equation. The paper examines the situation when the matrix that appears in the Levinson expansion has a double eigenvalue. Application is made to a fourth-order ODE with known special function solution