A micro-environmental study of the effect of temperature on the sex ratios of the loggerhead turtle, Caretta caretta, from Tongaland, Natal

Sex determination in C. caretta is, under natural conditions, dependent on incubation temperature. In general, below 27°C all hatchlings are male while above 29,3°C 80% or more are females. The sex ratios of the nests were also dependent on the time of season which is directly related to temperature. Metabolic heating of the nest was evident only towards the end of the critical period i.e. post-sexual differentiation. There was no correlation between sex ratios and the physical characteristics of the beach. The implications of temperature sex determination on the limitation of geographical populations are also discussed

The Minimally Tuned Minimal Supersymmetric Standard Model

The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV.Comment: 38 pages, including 2 appendices, 8 figure

Active damping based on decoupled collocated control

High-precision machines typically suffer from small but persistent vibrations. As it is difficult to damp these vibrations by passive means, research at the Drebbel Institute at the University of Twente is aimed at the development of an active structural element that can be used for vibration control. The active structural element, popularly referred to as ‘Smart Disc’, is based on a piezoelectric position actuator and a piezoelectric force sensor

Viscosity in spherically symmetric accretion

The influence of viscosity on the flow behaviour in spherically symmetric accretion, has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution, viscosity acts as a mechanism that detracts from the effectiveness of gravity. This has been conjectured to set up a limiting scale of length for gravity to bring about accretion, and the physical interpretation of such a length-scale has been compared with the conventional understanding of the so-called "accretion radius" for spherically symmetric accretion. For a perturbative presence of viscosity, it has also been pointed out that the critical points for inflows and outflows are not identical, which is a consequence of the fact that under the Navier-Stokes prescription, there is a breakdown of the invariance of the stationary inflow and outflow solutions -- an invariance that holds good under inviscid conditions. For inflows, the critical point gets shifted deeper within the gravitational potential well. Finally, a linear stability analysis of the stationary inflow solutions, under the influence of a perturbation that is in the nature of a standing wave, has indicated that the presence of viscosity induces greater stability in the system, than has been seen for the case of inviscid spherically symmetric inflows.Comment: 7 pages. Minor changes made in the version published in MNRA

Outcomes of Stereotactic Ablative Radiotherapy for Centrally Located Early-Stage Lung Cancer

Introduction:The use of stereotactic ablative radiotherapy (SABR) in centrally located early-stage lung tumors has been associated with increased toxicity. We studied outcomes after delivery of risk-adapted SABR of central tumors.Methods:SABR was delivered in eight fractions of 7.5 Gy to 63 such patients between 2003 and 2009. Of these, 37 patients had a tumor at a central hilar location, whereas 26 patients had tumors abutting the pericardium or mediastinal structures. Survival outcomes were compared with patients with peripheral tumors treated during the same time period using fewer fractions of SABR.Results:Median follow-up was 35 months. Late grade III toxicity was limited to chest wall pain (n = 2) and increased dyspnoea (n = 2). No grade IV/V toxicity was observed, but grade V toxicity could not be excluded with certainty in nine patients who died of cardiopulmonary causes. Distant metastases were the predominant cause of death; cardiovascular deaths were not associated with a paracardial tumor location. No significant differences in outcomes were observed between these 63 patients and 445 other SABR patients treated for peripheral early-stage lung tumors. Three-year local control rates were 92.6% and 90.2% (p = 0.9). Three-year overall survival rates were 64.3% and 51.1% with median survival rates of 47 and 36 months, in favor of the group of patients with central tumors (p = 0.09).Conclusions:Use of risk-adapted SABR delivered in eight fractions of 7.5 Gy did not result in excess toxicity for centrally located early-stage lung tumors, and clinical outcomes were comparable with those seen for peripheral lesions

Product Policy as an Instrument for Water Quality Management.

A main reason for the persistence of current water pollution lies in the diffuse character of many of its sources. For a large part such diffuse pollution is related to the production, use and waste of various kinds of products. For the reduction of this pollution, a product oriented policy strategy, based on interaction with stakeholders could be more successful than the traditional measures of direct regulation that were devised for point source reduction. In this article we identify different types of product policy, and explore the potential benefits and costs for water quality management. The methods that can be used in a product policy approach are illustrated with some examples. Although the specific advantages for water quality management have not been quantified yet, governments increasingly recognise the potential positive effects. In this context, the European Water Framework Directive, in stimulating product policy by enhancing public and stakeholders’ participation, can be considered to be part of a general development towards interactive water management

Diffusion Tensor Imaging in Alzheimer's disease

Attentional control and Information processing speed are central concepts in cognitive psychology and neuropsychology. Functional neuroimaging and neuropsychological assessment have depicted theoretical models considering attention as a complex and non-unitary process. One of its component processes, Attentional set-shifting ability, is commonly assessed using the Trail Making Test (TMT). Performance in the TMT decreases with increasing age in adults, Mild Cognitive Impairment (MCI) and Alzheimer’s Disease (AD). Besides, speed of information processing (SIP) seems to modulate attentional performance. While neural correlates of attentional control have been widely studied, there are few evidences about the neural substrates of SIP in these groups of patients. Different authors have suggested that it could be a property of cerebral white matter, thus, deterioration of the white matter tracts that connect brain regions related to set-shifting may underlie the age-related, MCI and AD decrease in performance. The aim of this study was to study the anatomical dissociation of attentional and speed mechanisms. Diffusion tensor imaging (DTI) provides a unique insight into the cellular integrity of the brain, offering an in vivo view into the microarchitecture of cerebral white matter. At the same time, the study of ageing, characterized by white matter decline, provides the opportunity to study the anatomical substrates speeded or slowed information processing. We hypothesized that FA values would be inversely correlated with time to completion on Parts A and B of the TMT, but not the derived scores B/A and B-A