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In this work, we employ the Karmarkar condition together with the notion of vanishing complexity (Herrera in Phys Rev D 97:044010, 2018) and isotropization technique to generate models of compact stars within the framework of complete geometric deformation. Starting off with the Kuchowicz ansatz as one of the metric potentials for the seed solution, we impose the Karmarkar condition to obtain fully the gravitational behaviour of a static compact object with anisotropic pressure. This solution is then subjected to the complete geometric deformation algorithm. The novelty in our work is to impose the condition of vanishing complexity and isotropization techniques in order to derive the deformation functions. We present two solutions of the resulting governing equations which are subjected to physical viability tests. We demonstrate that the presence of pressure anisotropy within the bounded object plays a key role in determining its stability. In addition, we show that the magnitude of the decoupling constant determines the direction of energy flow between the generic fluid and the fluid matter distribution. [ABSTRACT FROM AUTHOR]

In this work, we present a hierarchical solution-generating technique employing the Minimum Gravitational Decoupling (MGD) Method and the generalized concept of Complexity as applied to Class I spacetime for bounded compact objects in classical general relativity. Starting off with an anisotropic seed solution described by Class I spacetime, we apply the MGD technique with the constraint that the effective anisotropy vanishes which leads to an isotropic model. In addition, we produce a second family of solutions in which the Complexity factor [Herrera (Phys Rev D 97:044010, 2018)] for the seed solution and its MGD counterpart are the same. We discuss the physical plausibility of both classes of solutions as candidates for physically realizable compact objects. [ABSTRACT FROM AUTHOR]

In this work we explore the characteristics of a polytropic solution for the anisotropic stellar object within the framework of Einstein–Gauss–Bonnet (EGB) gravity. We introduce anisotropy via the minimally gravitational decoupling method. The analysis of the exact solution of the governing equation for the gravitational potentials reveals novel features of the compact object. We find that the EGB coupling constant and the decoupling parameter play important roles in enhancing and suppressing the effective density and radial profiles at each interior point of the bounded object. An analysis of the effective tangential pressure reveals a 'changeover' in the trends brought about by the EGB and decoupling constants which may be linked to the cracking observed in classical 4D stellar objects proposed by Herrera (Phys Lett A 165:206, 1992). [ABSTRACT FROM AUTHOR]

In this paper, we employ the Karmarkar condition to model a spherically symmetric radiating star undergoing dissipative gravitational collapse within the framework of classical general relativity. The collapse ensues from an initial static core satisfying the Karmarkar condition in isotropic coordinates and proceeds nonadiabatically by emitting energy in the form of a radial heat flux to the exterior Vaidya spacetime. We show that the dynamical nature of the collapse is sensitive to the initial static configuration that inherently links the embedding to the final remnant. Our model considered several physical tests on how an initially static stellar structure onset to a radiative collapse. [ABSTRACT FROM AUTHOR]

We model a radiating star undergoing dissipative gravitational collapse in the form of radial heat flux. The exterior of the collapsing star is described by the generalised Vaidya solution representing a mixture of null radiation and strings. Our model generalises previously known results of constant string density atmosphere to include inhomogeneities in the exterior spacetime. By utilising a causal heat transport equation of the Maxwell-Cattaneo form we show that relaxational effects are enhanced in the presence of inhomogeneities due to the string density. [ABSTRACT FROM AUTHOR]

We study the role played by an equation-of-state during gravitational collapse of a radiating star. Starting from an initially static matter configuration obeying a linear equation-of-state, the star loses hydrostatic equilibrium and undergoes dissipative collapse in the form of a radial heat flux. We show that the equation-of-state parameter plays an important role in determining the temperature profiles of the collapsing body. [ABSTRACT FROM AUTHOR]

Utilizing an ansatz developed by Maurya et al. we present a class of exact solutions of the Einstein-Maxwell field equations describing a spherically symmetric compact object. A detailed physical analysis of these solutions in terms of stability, compactness and regularity indicates that these solutions may be used to model strange star candidates. In particular, we model the strange star candidate Her X-1 and show that our solution conforms to observational data to an excellent degree of accuracy. An interesting and novel phenomenon which arises in this model is the fact that the relative difference between the electromagnetic force and the force due to the pressure anisotropy changing sign within the stellar interior. This may be an additional mechanism required for stability against cracking of the stellar object. [ABSTRACT FROM AUTHOR]

In this work we present an exact solution of the Einstein-Maxwell field equations describing compact charged objects within the framework of classical general relativity. Our model is constructed by embedding a four-dimensional spherically symmetric static metric into a five-dimensional flat metric. The source term for the matter field is composed of a perfect fluid distribution with charge. We show that our model obeys all the physical requirements and stability conditions necessary for a realistic stellar model. Our theoretical model approximates observations of neutron stars and pulsars to a very good degree of accuracy. [ABSTRACT FROM AUTHOR]

Starting off with two distinct initially static stellar cores (i) Florides interior (constant density, vanishing radial pressure) and (ii) Wyman interior (constant density, nonvanishing radial pressure), we explore the dynamics of these two models once hydrostatic equilibrium is lost. We show that although the time of formation of horizon, evolution of the mass and proper radius are independent of the chosen initially static configurations, there is a significant difference in the temperature profiles of the radiating bodies as the collapse proceeds. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effect of anisotropic stresses (radial and tangential pressures being unequal) for a collapsing fluid sphere dissipating energy in the form of radial flux. The collapse starts from an initial static sphere described by the Bowers and Liang solution and proceeds until the time of formation of the horizon. We find that the surface redshift increases as the stellar fluid moves away from isotropy. We explicitly show that the formation of the horizon is delayed in the presence of anisotropy. The evolution of the temperature profiles is investigated by employing a causal heat transport equation of the Maxwell-Cattaneo form. Both the Eckart and causal temperatures are enhanced by anisotropy at each interior point of the stellar configuration. [ABSTRACT FROM AUTHOR]

The Kramer radiating star uses the interior Schwarzschild solution as a seed solution to generate a model of dissipative collapse. We investigate the thermal behaviour of the radiating star by employing a causal heat transport equation. The causal temperature is explicitly determined for the first time by integrating the transport equation. We further show that the dissipation of energy to the exterior space-time renders the core more unstable than the cooler surface layers. [ABSTRACT FROM AUTHOR]

Introduction: Aminoglycosides used for treating multidrug-resistant (MDR) tuberculosis are ototoxic, leading to a need for audiological monitoring. While audiologists monitor ototoxicity, currently there are no guidelines on monitoring in the South African context. Therefore, the findings of this study might help to motivate the establishment of a more in-depth ototoxicity monitoring policy, which facilitates uniformity among audiologists managing patients with MDR tuberculosis. Therefore, the study aimed to describe the audiological practices employed by audiologists in the management of adult patients with MDR tuberculosis in South Africa. Method: A descriptive survey design was used. A questionnaire was developed and included elements of the American Speech-Language and Hearing Association (1994) guidelines for monitoring ototoxicity. Ninety-three audiologists contributed data to this study. Descriptive statistics were used in the analysis of the data. Results: Sixty-eight percent (%) of the respondents were aware of the international guidelines, 93% provided pre-treatment counselling and 87% conducted a baseline assessment. Nineteen per cent of the respondents conducted high-frequency audiometry, while 74% carried out a monthly evaluation, 72% performed a full audiological assessment after the cessation of the MDR tuberculosis treatment, and 96% conducted post-treatment counselling. Modifications to the international guidelines include not conducting speech and immittance audiometry, as well as testing certain frequencies. The reasons for these modifications include limited specialised equipment, time constraints, large caseloads and understaffed departments. Conclusion: There are no explicit guidelines on ototoxicity monitoring in South Africa. Consequently, audiologists are having to modify the international guidelines. Thus, there is no consistency in managing patients with MDR tuberculosis. This highlights the need for South Africa to develop context-relevant ototoxicity monitoring guidelines to appropriately manage patients with MDR tuberculosis. [ABSTRACT FROM AUTHOR]

We present a new family of spherically symmetric, static solutions of the Einstein field equations in isotropic, comoving coordinates. The radial pressure at each interior point of these models vanishes yet equilibrium is still possible. The constant density Florides solution which describes the gravitational field inside an Einstein cluster is obtained as a special case of our solution-generating method. We show that our solutions can be utilized to model strange star candidates such as Her. X-1, SAX J1808.4-3658(SS2), SAX J1808.4-3658(SS1) and PSR J1614-2230. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the role of causal heat transport in a spatially homogeneous, locally-rotationally symmetric (LRS) Bianchi type-V cosmological model. In particular, the causal temperature profile of the cosmological fluid is obtained within the framework of extended irreversible thermodynamics. We demonstrate that relaxational effects can alter the temperature profile when the cosmological fluid is out of hydrostatic equilibrium. [ABSTRACT FROM AUTHOR]

At sufficiently high pressures, wurtzite structure zinc oxide ( W-ZnO) can be transformed to the cubic rocksalt ( R-ZnO) structure. The R-ZnO exhibits semiconductor behavior with an indirect wide band gap of [ABSTRACT FROM AUTHOR]

Laser pyrolysis was chosen to synthesize tungsten trioxide starting with tungsten ethoxide precursor. The film was found to have a thickness that varied from 205 nm to 1 µm. X-ray diffraction and Raman spectroscopy confirmed the presence of a mixture of hexagonal and tetragonal phase WO3 in the synthesized film, as well as tungsten bronzes. It was evident that annealing greatly influenced the phases and types of structures formed, and EDXS was carried out in an attempt to quantify the tungstate bronzes to tungsten oxide. I-V curves of the films showed n-type semiconducting behaviour, but the mixed phase appeared to cause a similar behaviour of dopants in a semiconductor. The refractive index decreased with increasing wavelength and gave values of up to 21 at low wavelengths. The average optical band gap was found to be 3.6 eV from UV/Vis spectroscopy. Scanning Electron Microscopy (SEM) showed a mixture of nano- and microstructures after annealing. Nanorod structures were isolated and Pt-contacted using FIB for possible applications such as an active sensing medium in gas sensors. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

In this paper, we investigate the physics of a radiating star undergoing dissipative collapse in the form of a radial heat flux. Our treatment clearly demonstrates how the presence of shear affects the collapse process; we are in a position to contrast the physical features of the collapsing sphere in the presence of shear with the shear-free case. By employing a causal heat transport equation of the Maxwell--Cattaneo form we show that the shear leads to an enhancement of the core temperature thus emphasizing that relaxational effects cannot be ignored when the star leaves hydrostatic equilibrium. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effect of charge on the collapse of a radiating, shearing sphere. The junction conditions required for the smooth matching of a general spherically symmetric spacetime (in the absence of rotation) to the exterior Vaidya-Reissner-Nordström leads to a temporal evolution equation at the boundary of the collapsing star. We are in a position to integrate these equations in the presence of charge and shear. The solutions obtained here are new and generalize recent treatments of dissipative, shearing collapse to the charged case. [ABSTRACT FROM AUTHOR]

In this paper, we present an exact model of a spherically symmetric star undergoing dissipative collapse in the form of a radial heat flux. The interior of the star is matched smoothly to the generalized Vaidya line element representing a two-fluid atmosphere comprising null radiation and a string fluid. The influence of the string density on the thermal behavior of the model is investigated by employing a causal heat transport equation of Maxwell-Cattaneo form. [ABSTRACT FROM AUTHOR]

In this work, we are guided by the gravitational wave events GW 170817 and GW 190814 together with observations of neutron stars PSR J1614-2230, PSR J1903+6620, and LMC X-4 to model compact objects within the framework of Einstein–Gauss–Bonnet (EGB) gravity. In addition, we employ the extended gravitational decoupling (EGD) method to explore the impact of anisotropy by varying the decoupling parameter. We model strange quark stars in which the interior stellar fluid obeys the MIT Bag equation of state which represents a degenerated Fermi gas comprising of up, down, and strange quarks. In order to close the system of field equations describing the seed solution, we employ the Buchdahl ansatz for one of the metric functions. The θ sector is solved under the bifurcation: |$\epsilon =\theta ^0_0$| and |$P_r=\theta ^1_1$| leading to two new families of solutions. In order to test the physical viability of the models, we vary the EGB parameter (α) or the decoupling constant (β) to achieve the observed masses and radii of compact objects. Our models are able to account for low-mass stars for a range of β values while α is fixed. The present models mimic the secondary component of the GW 190814 with a mass range of 2.5–2.67 M⊙ and radii typically of the order of 11.76 |$^{+0.14}_{-0.19}$| km for large values of the EGB parameter and the decoupling constant. The energy exchange between fluids inside the stellar object is sensitive to model parameters which lead to stable configurations. [ABSTRACT FROM AUTHOR]

We analyse a new family of solutions to the Einstein field equations describing the collapse of a fluid sphere in the presence of heat flux and shear. These solutions ensure that the collapsing fluid is accelerating and provide a generalisation of the geodesic fluid models studied in earlier treatments. In particular, we demonstrate the role played by pressure in the dynamics of the collapse process. [ABSTRACT FROM AUTHOR]

In this paper we revisit the problem of modeling radiating stars in which the areal radius is equal to the proper radius throughout the stellar evolution. We provide a new family of solutions that completely describes the dynamical behaviour of these so-called Euclidean stars. The solution satisfies all the energy conditions, and importantly, admits a barotropic equation of state. [ABSTRACT FROM AUTHOR]

A recent study of dissipative collapse considered a contracting sphere in which the areal and proper radii are equal throughout its evolution. The interior space–time was matched to the exterior Vaidya space–time which generated a temporal evolution equation at the boundary of the collapsing sphere. We present a solution of the boundary condition which allows the study of the gravitational and thermodynamical behavior of this particular radiating model. [ABSTRACT FROM AUTHOR]

Abstract: Background: Colonic and intra-peritoneal rectal injuries may be managed by primary repair and extra-peritoneal rectal injuries by diverting colostomy. This study was undertaken to document our experience with this approach and to identify factors which might impact on outcome. Patients and methods: Prospective study of all patients treated for colon and rectal injuries in one surgical ward at King Edward VIII hospital, Durban, over a 7-year period (1998–2004). Demographic data, clinical presentation, findings at laparotomy and outcome were documented. Results: Of 488 patients undergoing laparotomy, 177 (36%) had injuries to the colon and rectum with age 29.8±10.9 years. Injury mechanisms were firearms (118) stabs (54) and blunt trauma (5). Delay before laparotomy was 10±9.3h. Complication and mortality rates were 36% and 17%, respectively. 68 patients (38%) required ICU management. Shock on admission and increased transfusion requirements were associated with a significantly increased mortality. Patients with delay ≤12h before laparotomy had a higher mortality rate than those with delay >12h. The mortality rate increased with the number of associated injuries and it was higher the higher the Injury Severity Score (ISS); it was similar for stabs, firearms and blunt trauma. Hospital stay was 9.5±9.2 days. Conclusion: We reaffirm that primary repair is appropriate for colonic and intra-peritoneal rectal injuries and that extra-peritoneal rectal injuries require diverting colostomy. Shock on admission, increased blood transfusion requirements, associated organ injury and severity of the injury were associated with high mortality. [Copyright &y& Elsevier]

We present the general junction conditions for the smooth matching of a spherically symmetric, shear-free spacetime to Vaidya’s outgoing metric across a four-dimensional time-like hypersurface in the presence of a cosmological constant. These results generalise earlier treatments by Santos and co-workers on radiating stellar models. We study the thermal evolution of a particular radiating model within the framework of extended irreversible thermodynamics. [ABSTRACT FROM AUTHOR]

This review provides an overview of the use of remote sensing data, the development of spectral reflectance indices for detecting plant water stress, and the usefulness of field measurements for ground-truthing purposes. Reliable measurements of plant water stress over large areas are often required for management applications in the fields of agriculture, forestry, conservation and land rehabilitation. The use of remote sensing technologies and spectral reflectance data for determining spatial patterns of plant water stress is widely described in the scientific literature. Airborne, space-borne and hand-held remote sensing technologies are commonly used to investigate the spectral responses of vegetation to plant stress. Earlier studies utilised multispectral sensors which commonly collect four to seven spectral bands in the visible and near-infrared region of the electromagnetic spectrum. Advances in sensor and image processor technology over the past 3 decades now allow for the simultaneous collection of several hundred narrow spectral bands resulting in more detailed hyperspectral data. The availability of hyperspectral data has led to the identification of several spectral indices that have been shown to be useful in identifying plant stress. Such studies have revealed strong linear relationships between plant pigment concentration and the visible (VIS) and near-infrared (NIR) reflectance, while plant water content has been linked to specific bands in the short-wave infrared (SWIR) region of the spectrum. Ground-truthing is essential to identifying useful reflectance information for detecting plant water stress, and four commonly used ground-based methods viz, predawn leaf water potential, leaf chlorophyll fluorescence, leaf pigment concentrations and leaf water content are reviewed for their, usefulness and practical application. [ABSTRACT FROM AUTHOR]

We investigate the causal temperature profiles in a recent model of a radiating star undergoing dissipative gravitational collapse without the formation of a horizon. It is shown that this simple exact model provides physically reasonable behaviour for the temperature profile within the framework of extended irreversible thermodynamics. [ABSTRACT FROM AUTHOR]

We study the effects of pressure anisotropy and heat dissipation in a spherically symmetric radiating star undergoing gravitational collapse. An exact solution of the Einstein field equations is presented in which the model has a Friedmann-like limit when the heat flux vanishes. The behavior of the temperature profile of the evolving star is investigated within the framework of causal thermodynamics. In particular, we show that there are significant differences between the relaxation time for the heat flux and the relaxation time for the shear stress. [ABSTRACT FROM AUTHOR]

In a recent approach in modeling a radiating relativistic star undergoing gravitational collapse the role of the Weyl stresses was emphasized. It is possible to generate a model which is physically reasonable by approximately solving the junction conditions at the boundary of the star. In this paper we demonstrate that it is possible to solve the Einstein field equations and the junction conditions exactly. This exact solution contains the Friedmann dust solution as a limiting case. We briefly consider the radiative transfer within the framework of extended irreversible thermodynamics and show that relaxational effects significantly alter the temperature profiles. [ABSTRACT FROM AUTHOR]

Ab initio and density functional theory calculations are presented of the structures and vibrational properties of the weakly-bound hydrogen-bonded species, (NH3)2 and (PH3)2. Earlier studies of the ammonia dimer have indicated that the structure of the most stable species, and the question of whether a particular structure is a genuine minimum or a transition state, is largely determined by the combination of the theory employed and the basis set used. This paper explores the performance of a variety of basis sets, used in conjunction with second-order Møller–Plesset perturbation theory (MP2), and with density functional theory (DFT), in an attempt to achieve convergence on the most favourable structures of these two aggregates. The ammonia dimer is found to contain a linear hydrogen bond in the eclipsed conformation, while the phosphine dimer is characterized by a blue-shifting hydrogen bond, in a centrosymmetric doubly bifurcated structure. [ABSTRACT FROM AUTHOR]

We present a simple nonstatic generalization of the isothermal universe. The cosmological fluid obeys a barotropic equation of state of the formp=a?. We employ a causal heat transport equation of the Maxwell-Cattaneo form to study the thermodynamical behavior of our model. [ABSTRACT FROM AUTHOR]

We present here a simple model of radiative gravitational collapse with radial heat flux which describes qualitatively the stages close to the formation of a superdense cold star. Starting with a static general solution for a cold star, the model can generate solutions for the earlier evolutionary stages. The temporal evolution of the model is specified by solving the junction conditions appropriate for radiating gravitational collapse. The results will be useful in constructing models for the evolution of X-ray pulsars, like Her X-1. [ABSTRACT FROM AUTHOR]

Hypochlorite which is generated electrolytically from seawater under optimized conditions was evaluated for its (i) bacterial sensitivity to Escherichia coli in comparison to commercial bleaches and (ii) utilization in the treatment of sanitary effluent. Effective bacterial growth inhibition occurs using the hypochlorite containing seawater. Waste water samples from sewage treatment plant, from two sampling points, i.e., one after primary treatment (Sample 1) and the second prior to the discharge of the effluent into the river (Sample 2) were analyzed. Sample 1 was subjected to the hypochlorite treatment and Sample 2 was used to assess the treatment work's efficiency. Quality parameters namely Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Dissolved Solids (DS), Suspended Solids (SS) were monitored at each sampling point. The addition of hypochlorite to sample at point 1 lowered the BOD and COD levels and improved the water quality. [ABSTRACT FROM AUTHOR]

We study the analogue of the Oppenheimer–Snyder model of a collapsing sphere of homogeneous dust on the Randall–Sundrum type brane. We show that the collapsing sphere has the Vaidya radiation envelope which is followed by the brane analogue of the Schwarzschild solution described by the Reissner–Nordstro¨m metric. The collapsing solution is matched to the brane generalized Vaidya solution and which in turn is matched to the Reissner–Nordstro¨m metric. The mediation by the Vaidya radiation zone is the new feature introduced by the brane. Since the radiating mediation is essential, we are led to the remarkable conclusion that a collapsing sphere on the brane does indeed, in contrast to general relativity, radiate null radiation. [Copyright &y& Elsevier]

Relaxational effects in stellar heat transport can in many cases be significant. Relativistic Fourier–Eckart theory is inherently quasi-stationary, and cannot incorporate these effects. The effects are naturally accounted for in causal relativistic thermodynamics, which provides an improved approximation to kinetic theory. Recent results, based on perturbations of a static star, show that relaxation effects can produce a significant increase in the central temperature and temperature gradient for a given luminosity. We use a simple stellar model that allows for non-perturbative deviations from staticity, and confirms qualitatively the predictions of the perturbative models. [ABSTRACT FROM AUTHOR]

In a recent paper [J. Math. Phys. 43, 4904 (2002)] Liu and Zhang present a time-dependent solution for a star which is immersed in a background radiation. This solution was obtained by analyzing equations arising from the analysis of a five-dimensional solution that contained their solution. We show that, while their analysis and conclusions are valid, their equations are unnecessarily restrictive when applied to the four-dimensional case. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper we present two new classes of solutions describing compact objects within the framework of five‐dimensional Einstein‐Gauss‐Bonnet (EGB) gravity. We employ the Complete Geometric Deformation (CGD) formalism which extends the Minimal Geometric Deformation (MGD) technique adopted in earlier investigations to generate anisotropic models from known isotropic solutions. The two solutions presented arise from mimicking the constraint for the pressure and density respectively which generate independent deformation functions. Rigorous physical tests show that contributions from CDG suppress the effective pressure but enhances the effective density and mass of the compact object, with the suppression/enhancement being modified by the EGB coupling constant. One of the highlights in our findings is that the deformation function along the radial component in CDG is nonzero at the boundary when we mimic both the pressure and density while in MGD we observe a vanishing of this deformation function at the boundary of the fluid configuration only for the pressure constraint. The difference in behavior of the deformation function at the surface predicts different stellar characteristics such as mass‐to‐radius and surface redshifts. In this paper two new classes of solutions are presented describing compact objects within the framework of five‐dimensional Einstein‐Gauss‐Bonnet (EGB) gravity. The Complete Geometric Deformation (CGD) formalism will be employed which extends the Minimal Geometric Deformation (MGD) technique adopted in earlier investigations to generate anisotropic models from known isotropic solutions. The two solutions presented arise from mimicking the constraint for the pressure and density respectively which generate independent deformation functions. Rigorous physical tests show that contributions from CDG suppress the effective pressure but enhances the effective density and mass of the compact object, with the suppression/enhancement being modified by the EGB coupling constant. One of the highlights in the findings is that the deformation function along the radial component in CDG is nonzero at the boundary when one mimics both the pressure and density while in MGD one observes a vanishing of this deformation function at the boundary of the fluid configuration only for the pressure constraint. The difference in behavior of the deformation function at the surface predicts different stellar characteristics such as mass‐to‐radius and surface redshifts. [ABSTRACT FROM AUTHOR]

A series of osmocene-containing carboxylic acids, Oc(CH2)mCOOH, where m = 1, 2 and 3, and osmocene-containing alcohols, Oc(CH2)nOH, where n = 1, 2, 3 and 4, were synthesised and characterised, using 1H NMR spectroscopy and infrared spectroscopy. Cyclic voltametric studies on the series of alcohols and carboxylic acids demonstrated a decrease in the formal reduction potential (E01) as the number of --CH2-- spacers increased. The crystal structures of 2-osmocenylacetonitrile and 2-osmocenylethanol were determined by single-crystal X-ray crystallography [ABSTRACT FROM AUTHOR]

A new class of solution describing an anisotropic stellar configuration satisfying Karmarkar’s condition i.e. spherically symmetric metric of embedding class 1, is reported. It has been shown that the compact star model is physically well-behaved and meet all the physical requirements for a stable configuration in hydrostatic equilibrium. Our model describes compact stars like Vela X-1 and 4U1608-52 to a very good approximation. [ABSTRACT FROM AUTHOR]

We investigate the role played by the cosmological constant during gravitational collapse of a radiating star with vanishing Weyl stresses in the interior. We highlight the role played by the cosmological constant during the latter stages of collapse. The evolution of the temperature of the collapsing body is studied by employing causal heat transport equation. We show that the inclusion of the cosmological constant enhances the temperature within the stellar core. [ABSTRACT FROM AUTHOR]

We model the gravitational behaviour of a radiating star when the exterior geometry is the generalised Vaidya spacetime. The interior matter distribution is shear-free and undergoing radial heat flow. The exterior energy momentum tensor is a superposition of a null fluid and a string fluid. An analysis of the junction conditions at the stellar surface shows that the pressure at the boundary depends on the interior heat flux and the exterior string density. The results for a relativistic radiating star undergoing nonadiabatic collapse are obtained as a special case. For a particular model we demonstrate that the radiating fluid sphere collapses without the appearance of the horizon at the boundary. [ABSTRACT FROM AUTHOR]

We investigate the gravitational collapse of a radiating sphere evolving into a final static configuration described by the interior Schwarzschild solution. The temperature profiles of this particular model are obtained within the framework of causal thermodynamics. The overall temperature evolution is enhanced by contributions from the temperature gradient induced by perturbations as well as relaxational effects within the stellar core. [ABSTRACT FROM AUTHOR]

The selection rules (SR's) for the Kronecker product (KP) of Si and Ge irreducible representations (irreps) are required to determine the intervalley scattering processes. The SR's for transitions between the lowest conduction band minima at Γ, X and L high symmetry points and the highest maximum of the valence band (VB) in the Brillouin zone of O7 h space group symmetry are determined. The symmetry of phonons due to electron-phonon (El-Ph) interaction follows from the KP's: L1 ⊗ Γ12( Γ2-), Δ1 Γ12( Γ2-), L1( L1+) ⊗ Δ1 for Ge and L1 ⊗ Γ15( Γ4-), Δ ⊗ Γ15( Γ4-), L1( L1+) ⊗ Δ1 for Si. The elements of El-Ph scattering tensors are linear combinations of the Clebsch-Gordon coefficients (CGC's). Here we have computed the coupling coefficients relevant to scattering tensors. Our theoretical results confirm the available experimental data. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

AbstractAim: To ascertain the prevalence and severity of phenytoin-induced gingival enlargement (PIGE) as well as the relationship between PIGE and risk factors. Method: An outpatient population of patients on phenytoin treatment and attending the epilepsy clinic at Prince Mshiyeni Memorial Hospital (PMMH) in Durban, South Africa, was requested to participate. A structured questionnaire was used to collect data on patients' demographics, social habits (e.g., drinking and smoking), dental and oral hygiene practices and medication history. Gingival enlargement, dental plaque and gingival bleeding was also measured to assess gingival health. Venous blood was collected for serum folate and phenytoin serum levels measurements. A regression analyses was then undertaken to ascertain the association between PIGE and the risk factors. Factors tested for correlation were serum phenytoin and folate levels, age, bacterial plaque, gingival inflammation, toothbrushing, smoking and alcohol consumption. The association between PIGE and the risk factors was assessed either individually, i.e., as a single entity or in combination – multifactorially. Results: Of the 134 patients studied, 62% had PIGE scores >=1, while 8% had a PIGE score of zero. With the exception of plaque, which showed a moderate association with PIGE (r=0.4), no other factor on its own was statistically significantly related to PIGE. In the multiple linear regression analysis, factors which on their own did not have a strong influence became more important. Bacterial plaque (p=0.0001), younger age (p=0.01) and higher free serum phenytoin levels (p=0.03), were associated with PIGE. Although known to be associated with periodontal diseases, smoking and alchol, (p=0.03 and p=0.04 respectively), appeared to give some protection against PIGE. Conclusion: Risk factors associated with PIGE may have a synergistic effect. Bacterial plaque, however, appears the most important determinant of PIGE severity. This latter finding emphasises the importance of instituting a preventive plaque-control programme, particularly in young patients on phenytoin therapy. [ABSTRACT FROM AUTHOR]

Scattering matrix for two phonon processes at k = 0 in Si and Ge of Oh7 symmetry is given. Also diagonalization of spin-orbit interaction Hamiltonian has been computed by means of Clebsh-Gordan coefficients. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]