T-spheres as a limit of Lemaitre-Tolman-Bondi solutions

In the Tolman model there exist two quite different branches of solutions - generic Lemaitre-Tolman-Bondi (LTB) ones and T-spheres as a special case. We show that, nonetheless, T-spheres can be obtained as a limit of the class of LTB solutions having no origin and extending to infinity with the areal radius approaching constant. It is shown that all singularities of T-models are inherited from those of corresponding LBT solutions. In doing so, the disc type singularity of a T-sphere is the analog of shell-crossing.Comment: 6 pages. 1 Reference added. To appear in Phys. Rev.

Redshift drift in axially symmetric quasi-spherical Szekeres models

Models of inhomogeneous universes constructed with exact solutions of Einstein's General Relativity have been proposed in the literature with the aim of reproducing the cosmological data without any need for a dark energy component. Besides large scale inhomogeneity models spherically symmetric around the observer, Swiss-cheese models have also been studied. Among them, Swiss-cheeses where the inhomogeneous patches are modeled by different particular Szekeres solutions have been used for reproducing the apparent dimming of the type Ia supernovae (SNIa). However, the problem of fitting such models to the SNIa data is completely degenerate and we need other constraints to fully characterize them. One of the tests which is known to be able to discriminate between different cosmological models is the redshift-drift. This drift has already been calculated by different authors for Lema\^itre-Tolman-Bondi (LTB) models. We compute it here for one particular axially symmetric quasi-spherical Szekeres (QSS) Swiss-cheese which has previously been shown to reproduce to a good accuracy the SNIa data, and we compare the results to the drift in the $\Lambda$CDM model and in some LTB models that can be found in the literature. We show that it is a good discriminator between them. Then, we discuss our model's remaining degrees of freedom and propose a recipe to fully constrain them.Comment: 15 pages, 7 figures, minor changes in title, text, figures and references; conclusions unchanged, this version matches the published versio

The hodograph method applicability in the problem of long-scale nonlinear dynamics of a thin vortex filament near a flat boundary

Hamiltonian dynamics of a thin vortex filament in ideal incompressible fluid near a flat fixed boundary is considered at the conditions that at any point of the curve determining shape of the filament the angle between tangent vector and the boundary plane is small, also the distance from a point on the curve to the plane is small in comparison with the curvature radius. The dynamics is shown to be effectively described by a nonlinear system of two (1+1)-dimensional partial differential equations. The hodograph transformation reduces that system to a single linear differential equation of the second order with separable variables. Simple solutions of the linear equation are investigated at real values of spectral parameter $\lambda$ when the filament projection on the boundary plane has shape of a two-branch spiral or a smoothed angle, depending on the sign of $\lambda$.Comment: 9 pages, revtex4, 6 eps-figure

The evolution of environmental auditing in Ukraine

Environmental policy shapes the future tendencies and ways of the regulation and govern environmental issues. According to McCormick environmental policy is defined as “any action deliberately taken to manage human activities with a view to prevent, reduce, or mitigate harmful effects on nature and natural resources, and ensure that man-made changed to the environment do not have harmful effects on humans” (McCormick 2001:21). To realize and regulate these activities different instruments of environmental policy have evolved and used around the world. Policy instruments are seen as “a set of techniques used by the executive power of a country to implement its policies” (Ryden and Karlsson 2012). Environmental auditing is one of such tools, which was developed in the 1970s in North America, “as management tool to examine and evaluate the compliance of facilities and operations with (increasingly numerous and complex) environmental laws and regulations” (Hunt and Jonson 1995:70) and then spread to the United Kingdom (UK), continental Europe and around the world. Environmental audit is a flexible tool of environmental policy that includes different stages of planning, risk assessment, testing, evaluating, concluding and reporting stages (Collier 1995). When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3628

The Upper Miocene of the Rostov Dome (Eastern Paratethys): Implication of the chronostratigraphy and bivalvia-based biostratigraphy

The Rostov Dome is located in the south of the Russian Platform. In the Late Miocene this area was embraced by the Eastern Paratethys. The implications of a recently developed Neogene chronostratigraphy to the studied area are discussed. The Sarmatian regional stage corresponds to the upper part of the Langhian, the entire Serravalian and the lower part of the Tortonian global stages; the Maeotian regional stage corresponds to the upper part of the Tortonian and the lowermost horizons of the Messinian global stages; the Pontian regional stage corresponds to most of the Messinian and the lowermost Zanclean global stages. A first Bivalvia-based bio-stratigraphic framework is proposed for the territory of the Rostov Dome. Five biozones were established within the Serravalian-Messinian: Tapes vitalianus, Cerastoderma fittoni-Cerastoderma subfittoni, Congeria panticapaea, Congeria amygdaloides navicula and Monodacna pseudocatillus-Prosodacna schirvanica

Proportion of Mesozoic sedimentary rock types: data from northern Eurasia reveal similarities to North American patterns

Abstract The Mesozoic stratigraphic record of northern Eurasia includes a total of 1,739 formations. The proportion of conglomerate, sandstone + siltstone, shale, carbonates, evaporites, siliceous rocks, and volcanics + volcaniclastics among sedimentary complexes are evaluated for each epoch of the Mesozoic. Sandstone, shale, and conglomerate occur in 86%, 71%, and 42% of formations respectively. Less common are carbonates (28%) and volcanics and volcaniclastics (24%), whereas evaporites and siliceous rocks are rare (< 5%). The proportion of particular sedimentary rock types fluctuates throughout the Mesozoic. The proportion of sandstone + siltstone changes quite similarly to that of shale. A comparison of stratigraphic data from northern Eurasia and North America reveals some similarities, including a Lower Triassic increase in the conglomerate proportion, a Middle-Upper Triassic increase in the proportion of siliceous rocks, Upper Triassic-Lower Jurassic and Upper Jurassic-Lower Cretaceous “clastic spikes”, and a Middle-Upper Jurassic “carbonate-evaporite spike”. They may reflect any global-scale processes. Increases in clastic deposition coincided with eustatic lowstands, whereas voluminous accumulation of carbonates and evaporites tended to coincide with global sea-level rises. It remains unclear whether global climate was responsible for changes in the proportion of sedimentary rock types

Global carbonate accumulation from 145 Ma to Present (Cretaceous-Cenozoic): a new continental-scale analysis

Abstract Analysis of continental-scale lithostratigraphic data may facilitate an understanding of global sedimentary processes. The number of carbonate-bearing formations established in northern Eurasia (430 in total), northern Africa and Arabia (47 in total), and India (98 in total) is calculated per epochs for the last 145 Ma. The results show maxima in the Late Cretaceous, the Eocene, and the Miocene and minima in the Paleocene, the Oligocene, and the Pliocene. The Quaternary records are somewhat ambiguous. The similarity of the patterns established in the three regions argues for a single globalscale mechanism of carbonate accumulation. The noted patterns also coincide well with some modeled changes in the global amount of carbonates accumulated by epoch. Moreover, increases in the amount of carbonates in the Late Cretaceous and the Eocene, and a decrease in the Paleocene, reflect true changes in the accumulation rates. The global process of carbonate accumulation might have been controlled, at least, by eustatic changes (sea-level rise led to broad transgressions on continental margins and consequently to expansion of shelfal paleoenvironments) and climate dynamics (warm water facilitated carbonate production). Interestingly, no dependence between the global carbonate accumulation and marine biodiversity dynamics is established