Degeneracy in exotic gravitational lensing

We present three different theoretically foreseen, but unusual, astrophysical situations where the gravitational lens equation ends up being the same, thus producing a degeneracy problem. These situations are (a) the case of gravitational lensing by exotic stresses (matter violating the weak energy condition and thus having a negative mass, particular cases of wormholes solutions can be used as an example), (b) scalar field gravitational lensing (i.e. when considering the appearance of a scalar charge in the lensing scenario), and (c) gravitational lensing in closed universes (with antipodes).The reasons that lead to this degeneracy in the lens equations, the possibility of actually encountering it in the real universe, and eventually the ways to break it, are discussed.Comment: Accepted for publication in Modern Physics Letters

Cosmological Tests for a Linear Coasting Cosmology

A strictly linear evolution of the scale factor is a characteristic feature in several classes of alternative gravity theories, as also in the standard (big-bang) model with specially chosen matter equation of state. In this article we report that this model is consistent with gravitational lensing statistics (within $1\sigma$) and accomodates old high-redshift galaxies. We finally conclude that linear coasting cosmology, \a(t) = t, is not ruled out basis of these observational tests

Motion of a Vector Particle in a Curved Spacetime. II First Order Correction to a Geodesic in a Schwarzschild Background

The influence of spin on a photon's motion in a Schwarzschild and FRW spacetimes is studied. The first order correction to the geodesic motion is found. It is shown that unlike the world-lines of spinless particles, the photons world-lines do not lie in a plane.Comment: 14 pages, LaTeX2e, second paper in the series (the first one: gr-qc/0110067), replaced with typos and style corrected version, accepted in MPL

THE EFFECT OF “FAN” LIMB LENGTHENING TECHNIQUE ON MORPHOFUNCTIONAL STATE OF THE FIRST SENSITIVE NEURONS OF THE MOTOR ANALYZER (EXPERIMENTAL MORPHOLOGICAL STUDY)

The experiment was performed on 10 adult dogs underwent tibial lengthening by 14—18 % from the initial length using a "fan" technique interchanging weekly active periods of dosed lengthening on various muscle groups and. their weekly rest. This effect created sufficiently favourable conditions for bone distraction regenerate formation and functioning of the first sensitive neurons of the motor analyzer

Hyperfine frequency shift in two-dimensional atomic hydrogen

We propose the explanation of a surprisingly small hyperfine frequency shift in the two-dimensional (2D) atomic hydrogen bound to the surface of superfluid helium below 0.1 K. Owing to the symmetry considerations, the microwave-induced triplet-singlet transitions of atomic pairs in the fully spin-polarized sample are forbidden. The apparent nonzero shift is associated with the density-dependent wall shift of the hyperfine constant and the pressure shift due to the presence of H atoms in the hyperfine state $a$ not involved in the observed $b\to c$ transition. The interaction of adsorbed atoms with one another effectively decreases the binding energy and, consequently, the wall shift by the amount proportional to their density. The pressure shift of the $b\to c$ resonance comes from the fact that the impurity $a$-state atoms interact differently with the initial $b$-state and final $c$-state atoms and is also linear in density. The net effect of the two contributions, both specific for 2D hydrogen, is comparable with the experimental observation. To our knowledge, this is the first mentioning of the density-dependent wall shift. We also show that the difference between the triplet and singlet scattering lengths of H atoms, $a_t-a_s=30(5)$ pm, is exactly twice smaller than the value reported by Ahokas {\it et al.}, Phys. Rev. Lett. {\bf101}, 263003 (2008).Comment: 4 pages, no figure

КАФЕДРА ЕНДОКРИНОЛОГІЇ ЛЬВІВСЬКОГО НАЦІОНАЛЬНОГО МЕДИЧНОГО УНІВЕРСИТЕТУ ІМЕНІ ДАНИЛА ГАЛИЦЬКОГО: ІСТОРІЯ ТА СЬОГОДЕННЯ

The aim of the work – to recreate and analyze the main stages in the department establishment, to highlight the main areas of educational and scientific activities.   The main body. The Department of Endocrinology – one of the first in Ukraine as a separate unit – was established in 1978 on the basis of the Lviv Regional Endocrinology Dispensary; was led by Doctor of Medical Sciences, professor Ya. I. Tomashevskyi. Scientific school created by him studied conditions of hormonal regulation of glycolysis and gluconeogenesis during formation of diabetes mellitus, thyroid gland pathology, autoimmune polyendocrine syndrome. Under the direction of Doctor of Medical Sciences, professor O. O. Serhiiko, who led the department from 1999 to 2013, studies on metabolic disorders in diabetes mellitus were conducted. In 2014 the head of the department became Doctor of Medical Sciences, Associate Professor A. M. Urbanovych, her scientific research is related to pathogenesis of cardiovascular diseases during diabetes mellitus and obesity, the role of adipose tissue hormones in the development of endocrinopathies. Together with the department team she continues and creatively develops the scientific, pedagogical and clinical traditions of the Lviv Endocrinological School. The activity is analyzed and the main achievements of the department are presented at the present stage. Conclusions. An analysis of the historical experience of the establishment and development of the department of endocrinology showed the existence of a long tradition of formation of the teaching staff, the professional training of doctors-endocrinologists, the unity and constant interrelation of all types of activities in the formation of this category of specialists.Мета роботи – відтворити й проаналізувати основні етапи становлення кафедри, висвітлити основні напрямки педагогічної та наукової діяльності. Основна частина. Кафедра ендокринології – одна з перших в Україні як окремий підрозділ – була створена 1978 року на базі Львівського обласного ендокринологічного диспансеру; її очолив доктор медичних наук, професор Я. І. Томашевський. Головним напрямом створеної ним наукової школи стали дослідження станів гормональної регуляції процесів гліколізу та глюконеогенезу на етапах формування цукрового діабету, патології щитоподібної залози, автоімунного поліендокринного синдрому. Під керівництвом доктора медичних наук, професора О. О. Сергієнка, який завідував кафедрою з 1999 до 2013 року, здійснювалися дослідження порушень метаболізму при цукровому діабеті. У 2014 році кафедру очолила доктор медичних наук, доцент А. М. Урбанович, її наукові дослідження стосуються патогенезу серцево-судинних захворювань при цукровому діабеті та ожирінні, ролі гормонів жирової тканини у розвитку ендокринопатій. Проаналізована діяльність та наведені основні досягнення кафедри на сучасному етапі. Висновок. Аналіз історичного досвіду становлення і розвитку кафедри ендокринології засвідчив існування тривалої традиції формування професорсько-викладацького колективу, фахової підготовки лікарів-ендокринологів, єдності та постійного взаємозв’язку всіх видів діяльності у становленні цієї категорії спеціалістів

Microlensing by natural wormholes: theory and simulations

We provide an in depth study of the theoretical peculiarities that arise in effective negative mass lensing, both for the case of a point mass lens and source, and for extended source situations. We describe novel observational signatures arising in the case of a source lensed by a negative mass. We show that a negative mass lens produces total or partial eclipse of the source in the umbra region and also show that the usual Shapiro time delay is replaced with an equivalent time gain. We describe these features both theoretically, as well as through numerical simulations. We provide negative mass microlensing simulations for various intensity profiles and discuss the differences between them. The light curves for microlensing events are presented and contrasted with those due to lensing produced by normal matter. Presence or absence of these features in the observed microlensing events can shed light on the existence of natural wormholes in the Universe.Comment: 16 pages, 24 postscript figures (3 coloured), revtex style, submitted to Phys. Rev.

A program for a problem free Cosmology within a framework of a rich class of scalar tensor theories

A search for a problem free cosmology within the framework of an effective non - minimally coupled scalar tensor theory is suggested. With appropriate choice of couplings in variants of a Lee - Wick model [as also in a model supporting Q - ball solutions], non topological solutions [NTS's], varying in size upto 10 kpc to 1 Mpc can exist. We explore the properties of a ``toy'' Milne model containing a distribution of NTS domains. The interior of these domains would be regions where effective gravitational effects would be indistinguishable from those expected in standard Einstein theory. For a large class of non - minimal coupling terms and the scalar effective potential, the effective cosmological constant identically vanishes. The model passes classical cosmological tests and we describe reasons to expect it to fare well as regards nucleosynthesis and structure formation.Comment: 20 pages, Plain Tex, references added and expanded the previous version of article, 2 figures available from [email protected]