Role of pressure anisotropy on relativistic compact stars

We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina and Orlyanskii [Ukr. Phys. J. 36, 885 (1991)] type in order to solve the Einstein field equations. An additional prescription we make is that the pressure anisotropy parameter takes the functional form proposed by Lake [Phys. Rev. D 67, 104015 (2003)]. Specifying these two geometric quantities allows for further analysis to be carried out in determining unknown constants and obtaining a limit of the mass-radius diagram, which adequately describes compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium and the stability of such compact objects. Then, we investigate other physical features of this models, such as the energy conditions, speeds of sound and compactness of the star in detail and show that our results satisfy all the required elementary conditions for a physically acceptable stellar model. The results obtained are useful in analyzing the stability of other anisotropic compact objects like white dwarfs, neutron stars, and gravastars.Comment: 11 pages, 4 figures; v2:, texts are improved and updated to match journal versio

The Effects of Different Intensity of Thinning on the Development in Scots Pine (Pinus sylvestris L.) Stands in Kazakh Uplands

The search for more accurate methods of predicting the growth and development of forest stands became the most urgent task set for foresters of Kazakhstan to determine the permissible interventions in the natural course of the life of plantings, provide high durability and resilience in forests. The aim of the study was to identify the effects of diameter and density of Scots pine stands of Kazakh Uplands on their growth and productivity and the related productivity of single plantation stands taking into account the conditions of growth and development of internal factors as well as further study of the methodology for assessing the forestry cost-effectiveness and improvement thinning. To achieve this aim, effects of varied felling intensities on Scots pine stands were studied. The most common two forest types in upland Scots pine forests were chosen as permanent sample plots; the dead pine-lichen and moss pine-grass. The results showed that improvement thinning of moderate and severe intensity which are more profitable should be done in Scots pine forests of Kazakh Upland as well as carrying out such thinning increases the yield of the larger logs and increases the value of the left stand

Review of the fast growing forest tree species in Turkey

Los antecedentes de la utilización de especies de crecimiento rápido en Turquía tienen se remontan a 50 años y en los últimos 35-40 años se ha abrodado desde un punto de vista científico. Eucalyptus camaldulensis Dehn., E. grandis W.Hill., Pinus pinaster Ait., P. radiata D. Don., chopos híbridos, algunos clones de Populus deltoides Bartr. ex Marsh. y P. nigra L. son las especies más importantes por su mayor utilización en ensayos de especies, orígenes y en plantaciones. Aunque las especies y orígenes americanas son los más usados en los ensayos, los resultados esperados no han podido ser alcanzados debido al bajo número de clones y orígenes, establecidos en los experimentos que no representan el área de distribución natural. Junto con estas especies, los estudios deberían centrarse en Pinus brutia Ten. que tiene una amplia área de distribución natural en Turquía, elevado potencial y caracteres relacionados con el crecimiento rápido. Además, P. brutia esta considerado como una especie que podría cubrir el déficit de suministro a largo plazo. También, los estudios deberían ocuparse de Fraxinus angustifolia Wahl. subsp. oxycarpa Bieb ex Willd., Salix excelsa J. F. Gmelin., S. Alba L., Pterocarya fraxinifolia Spach. y Alnus glutinosa Gaertn. subsp. barbata (C. A. Mey.) Yalt que fueron probados en varias regiones y mostraron mejores características de crecimiento rápido que otras especies de aliso indígenas._____________________________________The fast growing species have 50 year-old political and 35-40 year-old scientific background in Turkey. Eucalyptus camaldulensis Dehn., E. grandis W.Hill., Pinus pinaster Ait., P. radiata D. Don., hybrid poplars, some clones of Populus deltoides Bartr. ex Marsh. and P. nigra L. are the most important species for obtaining a great deal of progress in species and origin experiments and starting the plantation phase in Turkey. In fast growing species process; although the American species and origins are mostly used, the desired outcomes could not be achived because of establishing the experiments with few number of clones and origins, which didn’t represent the natural distribution area. Along with these species, studies should be focused on Pinus brutia Ten. which has broad natural distribution area in Turkey, improvement potential and fast growing character. Furthermore, P. brutia is evaluated as a species which will close the supply deficit in long run. Also, studies should be performed on Fraxinus angustifolia Wahl. subsp. oxycarpa Bieb ex Willd., Salix excelsa J. F. Gmelin., S. alba L., Pterocarya fraxinifolia Spach. and Alnus glutinosa Gaertn. subsp. barbata (C. A. Mey.) Yalt. which was experimented in regional base and showed the faster growing character than the other indigenous alder species and native species

The Finslerian wormhole models

We present models of wormhole under the Finslerian structure of spacetime. This is a sequel of our previous work (Eur Phys J 75:564, 2015) where we constructed a toy model for compact stars based on the Finslerian spacetime geometry. In the present investigation, a wide variety of solutions are obtained that explore wormhole geometry by considering different choices for the form function and energy density. The solutions, like the previous work, are revealed to be physically interesting and viable models for the explanation of wormholes as far as the background theory and literature are concerned.Comment: 9 pages and 7 figue

Relativistic compact stars with charged anisotropic matter

In this article we perform a detailed theoretical analysis for a class of new exact solutions with anisotropic fluid distribution of matter for compact objects in hydrostatic equilibrium. To achieve this we call the relation between the metric functions, namely, embedding class one condition. The investigation is carried out by generalising the properties of a spherical star with an emphasis on hydrostatic equilibrium equation, i.e., the generalised Tolman-Oppenheimer-Volkoff equation, in our understanding of these compact objects. We match the interior solution to an exterior Reissner-Nordstrom solution, and study some physical features of this models, such as the energy conditions, speeds of sound, and mass - radius relation of the star. We also show that obtained solution is compatible with observational data for compact object Her X-1.Comment: v2: two column, 14 pages, many figures, version to appear in Chinese Physics

Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap

We study the effects of the spin orbit interaction (SOI) of light in an optical trap and show that the propagation of the tightly focused trapping beam in a stratified medium can lead to significantly enhanced SOI. For a plane polarized incident beam the SOI manifests itself by giving rise to a strong anisotropic linear diattenuation effect which produces polarization-dependent off-axis high intensity side lobes near the focal plane of the trap. Single micron-sized asymmetric particles can be trapped in the side lobes, and transported over circular paths by a rotation of the plane of input polarization. We demonstrate such controlled motion on single pea-pod shaped single soft oxometalate (SOM) particles of dimension around $1\times 0.5\mu$m over lengths up to $\sim$15 $\mu$m . The observed effects are supported by calculations of the intensity profiles based on a variation of the Debye-Wolf approach. The enhanced SOI could thus be used as a generic means of transporting mesoscopic asymmetric particles in an optical trap without the use of complex optical beams or changing the alignment of the beam into the trap.Comment: 9 pages, 7 figure

Homogeneous Relaxation at Strong Coupling from Gravity

Homogeneous relaxation is a ubiquitous phenomenon in semiclassical kinetic theories where the quasiparticles are distributed uniformly in space, and the equilibration involves only their velocity distribution. For such solutions, the hydrodynamic variables remain constant. We construct asymptotically AdS solutions of Einstein's gravity dual to such processes at strong coupling, perturbatively in the amplitude expansion, where the expansion parameter is the ratio of the amplitude of the non-hydrodynamic shear-stress tensor to the pressure. At each order, we sum over all time derivatives through exact recursion relations. We argue that the metric has a regular future horizon, order by order in the amplitude expansion, provided the shear-stress tensor follows an equation of motion. At the linear order, this equation of motion implies that the metric perturbations are composed of zero wavelength quasinormal modes. Our method allows us to calculate the non-linear corrections to this equation perturbatively in the amplitude expansion. We thus derive a special case of our previous conjecture on the regularity condition on the boundary stress tensor that endows the bulk metric with a regular future horizon, and also refine it further. We also propose a new outlook for heavy-ion phenomenology at RHIC and ALICE.Comment: 60 pages, a section titled "Outlook for RHIC and ALICE" has been added, accepted for publication in Physical Review