Bianchi Type-II String Cosmological Models in Normal Gauge for Lyra's Manifold with Constant Deceleration Parameter

The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological models representing massive strings in normal gauge for Lyra's manifold by applying the variation law for generalized Hubble's parameter that yields a constant value of deceleration parameter. The variation law for Hubble's parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's modified field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive string cosmological models for which we assume that the expansion ($\theta$) in the model is proportional to the component $\sigma^{1}_{~1}$ of the shear tensor $\sigma^{j}_{i}$. This condition leads to $A = (BC)^{m}$, where A, B and C are the metric coefficients and m is proportionality constant. Our models are in accelerating phase which is consistent to the recent observations. It has been found that the displacement vector $\beta$ behaves like cosmological term $\Lambda$ in the normal gauge treatment and the solutions are consistent with recent observations of SNe Ia. It has been found that massive strings dominate in the decelerating universe whereas strings dominate in the accelerating universe. Some physical and geometric behaviour of these models are also discussed.Comment: 24 pages, 10 figure

Ethical and Scientific Considerations Regarding Animal Testing and Research

In 1959, William Russell and Rex Burch published the seminal book, The Principles of Humane Experimental Technique, which emphasized reduction, refinement, and replacement of animal use, principles which have since been referred to as the ‘‘3 Rs’’. These principles encouraged researchers to work to reduce the number of animals used in experiments to the minimum considered necessary, refine or limit the pain and distress to which animals are exposed, and replace the use of animals with non-animal alternatives when possible. Despite the attention brought to this issue by Russell and Burch and since, the number of animals used in research and testing has continued to increase, raising serious ethical and scientific issues. Further, while the ‘‘3 Rs’’ capture crucially important concepts, they do not adequately reflect the substantial developments in our new knowledge about the cognitive and emotional capabilities of animals, the individual interests of animals, or an updated understanding of potential harms associated with animal research. This Overview provides a brief summary of the ethical and scientific considerations regarding the use of animals in research and testing, and accompanies a Collection entitled Animals, Research, and Alternatives: Measuring Progress 50 Years Later, which aims to spur ethical and scientific advancement

Analyses of cerebral microdialysis in patients with traumatic brain injury: relations to intracranial pressure, cerebral perfusion pressure and catheter placement

<p>Abstract</p> <p>Background</p> <p>Cerebral microdialysis (MD) is used to monitor local brain chemistry of patients with traumatic brain injury (TBI). Despite an extensive literature on cerebral MD in the clinical setting, it remains unclear how individual levels of real-time MD data are to be interpreted. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) are important continuous brain monitors in neurointensive care. They are used as surrogate monitors of cerebral blood flow and have an established relation to outcome. The purpose of this study was to investigate the relations between MD parameters and ICP and/or CPP in patients with TBI.</p> <p>Methods</p> <p>Cerebral MD, ICP and CPP were monitored in 90 patients with TBI. Data were extensively analyzed, using over 7,350 samples of complete (hourly) MD data sets (glucose, lactate, pyruvate and glycerol) to seek representations of ICP, CPP and MD that were best correlated. MD catheter positions were located on computed tomography scans as pericontusional or nonpericontusional. MD markers were analyzed for correlations to ICP and CPP using time series regression analysis, mixed effects models and nonlinear (artificial neural networks) computer-based pattern recognition methods.</p> <p>Results</p> <p>Despite much data indicating highly perturbed metabolism, MD shows weak correlations to ICP and CPP. In contrast, the autocorrelation of MD is high for all markers, even at up to 30 future hours. Consequently, subject identity alone explains 52% to 75% of MD marker variance. This indicates that the dominant metabolic processes monitored with MD are long-term, spanning days or longer. In comparison, short-term (differenced or Δ) changes of MD vs. CPP are significantly correlated in pericontusional locations, but with less than 1% explained variance. Moreover, CPP and ICP were significantly related to outcome based on Glasgow Outcome Scale scores, while no significant relations were found between outcome and MD.</p> <p>Conclusions</p> <p>The multitude of highly perturbed local chemistry seen with MD in patients with TBI predominately represents long-term metabolic patterns and is weakly correlated to ICP and CPP. This suggests that disturbances other than pressure and/or flow have a dominant influence on MD levels in patients with TBI.</p

Psychological and ethical issues in third party assisted conception and surrogate motherhood

The continuing increase in babies born via third party assisted conception (AC) and surrogate motherhood across the world shows the success of and medical and social demand for third party interventions in family building. However, with the increasing use of such interventions world-wide, commercialisation and commodification have proliferated. This in turn has led to inequality in access to AC services, in choice of third party input, and in questionable human rights and psychosocial welfare issues. Transitioning to parenthood using third party AC and surrogate motherhood, in addition to requiring equality in access, also demand accuracy of birth and genetic information. In the absence of accurate record keeping, continuing practices of anonymity, and marginalization of the contribution of donors and surrogates, psychological, social, health and ethical questions are raised for donors, recipients and potentially for (genetic, gestational) part, half and full offspring, siblings and others in the extended family such as grandparents

Participative Leadership and Organizational Identification in SMEs in the MENA Region: Testing the Roles of CSR Perceptions and Pride in Membership

The aim of this research is to explore the process linking participative leadership to organizational identification. The study examines the relationship between participative leadership and internal CSR perceptions of employees and also investigates the role that pride in membership plays in the affiliation of CSR perceptions with organizational identification. By studying these relationships, the paper aspires to contemplate new presumed mediators in the association of participative leadership with organizational identification as well as determine a possible novel antecedent of employee CSR perceptions. Empirical evidence is provided from data that was collected through a survey distributed to employees working for small- and medium-sized enterprises in three countries in the Middle East and North Africa regions, particularly the United Arab Emirates, Lebanon, and Tunisia. Findings show that participative leadership leads to positive internal CSR perceptions of employees and that these CSR perceptions lead to pride in membership which, in turn, results in organizational identification. Implications of these findings are also discussed

Comparative analysis of the corneal birefringence pattern in healthy children and adults

Purpose: To undertake a comparative analysis of the corneal shape, thickness and isochromatics in the eyes of children and adults in order to determine the extent of similarities and differences between the cohorts. Methods: The study involved 24 children (aged 8 years) and 37 young White adults (aged between 22–24 years) with no apparent or known health or ocular conditions. Measurements were made of corneal radius of curvature, both central (CCT) and paracentral (PCT) corneal thickness and intraocular pressure (IOP). Images of the isochromatics were captured using a slit lamp and a circular polarizer. The geometry of fringe I and II of the isochromatics was analysed. Results: Statistically significant differences were found between CCT and PCT in nasal and temporal regions for both the children and adult cohorts. The same trends were observed in the radii of the cornea. Statistically significant differences between side lengths and angles of isochromatic fringes were found. No differences in asymmetry of shape for fringe I between adults and children were detected; greater symmetry was seen in fringe II in children than for adults. Conclusions: The asymmetry in corneal shape and curvature contributes to the shape of the isochromatic fringes. This is likely linked to the orientation and parameters of the collagen fibres and to the muscles’ forces, and be relevant for surgical procedures such as corneal transplantation