Evaluating the AdS dual of the critical O(N) vector model

We argue that the AdS dual of the three dimensional critical O(N) vector model can be evaluated using the Legendre transform that relates the generating functionals of the free UV and the interacting IR fixed points of the boundary theory. As an example, we use our proposal to evaluate the minimal bulk action of the scalar field that it is dual to the spin-zero ``current'' of the O(N) vector model. We find that the cubic bulk self interaction coupling vanishes. We briefly discuss the implications of our results for higher spin theories and comment on the bulk-boundary duality for subleading N.Comment: 17 pages, 1 figure, v2 references added, JHEP versio

Holography of the N=1 Higher-Spin Theory on AdS4

We argue that the N=1 higher-spin theory on AdS4 is holographically dual to the N=1 supersymmetric critical O(N) vector model in three dimensions. This appears to be a special form of the AdS/CFT correspondence in which both regular and irregular bulk modes have similar roles and their interplay leads simultaneously to both the free and the interacting phases of the boundary theory. We study various boundary conditions that correspond to boundary deformations connecting, for large-N, the free and interacting boundary theories. We point out the importance of parity in this holography and elucidate the Higgs mechanism responsible for the breaking of higher-spin symmetry for subleading N.Comment: 19 page

Calibration curves and the chronology of key monuments at Sayan-Altai

Studies of the chronology of the elite barrows at Sayan-Altai are of a great importance for the determination of the origin and development of the cultures of the Scythian period. In this work dendrochronology and radiocarbon dating have been combined. Statistical calculations were used to obtain the best fit of the radiocarbon dates for the tree-ring series to the bidecadal calibration curve and thus to determine the zero point of the floatin g tree-ring chronology on the calendar time scale. The results obtained position the zero point of the floating tree-ring series in the calendar time period 380–420 BC with the confidence probability of 0.95. The goodness of fit can be improved by shifting the Arzhan tree-ring dates relative to the other tree-ring scale by 40 years. For all cases the age of the Arzhan barrow lies in the limit of 800 years BC. The results from chronological investigations of the constructions at the elite barrows of Sayan-Altai are summarised

Analysis of Higher Spin Field Equations in Four Dimensions

The minimal bosonic higher spin gauge theory in four dimensions contains massless particles of spin s=0,2,4,.. that arise in the symmetric product of two spin 0 singletons. It is based on an infinite dimensional extension of the AdS_4 algebra a la Vasiliev. We derive an expansion scheme in which the gravitational gauge fields are treated exactly and the gravitational curvatures and the higher spin gauge fields as weak perturbations. We also give the details of an explicit iteration procedure for obtaining the field equations to arbitrary order in curvatures. In particular, we highlight the structure of all the quadratic terms in the field equations.Comment: Latex, 30 pages, several clarifications and few references adde

Scalar Field Corrections to AdS_4 Gravity from Higher Spin Gauge Theory

We compute the complete contribution to the stress-energy tensor in the minimal bosonic higher spin theory in D=4 that is quadratic in the scalar field. We find arbitrarily high derivative terms, and that the total sign of the stress-energy tensor depends on the parity of the scalar field.Comment: 15 pages + appendix (30 pages

КОСТНАЯ И МЯГКОТКАННАЯ ИНТЕГРАЦИЯ ПОРИСТЫХ ТИТАНОВЫХ ИМПЛАНТАТОВ (ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ)

Aim. It’s common that revision arthroplasty of the large joints demands replacing of bone defects of irregular geometrical shapes and simultaneous restoring of support ability and ability to integrate surrounding muscular and tendinous structures into an implant that is required for a complete restoration of joint function.The purpose. To experimentally study the process of integration for muscular and bone tissue as well as tendinous and ligamentous structures into porous titanium materials.Material and methods. During in vivo experiment the authors created a standardized bone defect in 6 rabbits of chinchilla breed at the point of patella ligament attachment as well as a delamination area of muscular tissue in latissimus dorsi. Both knee joints and both latissimus dorsi were used in each animal. Study group included titanium implants with three-dimensional mesh structure. Control group — solid titanium implants with standard porosity. Titanium implants were produced by additive technologies with preliminary prototyping. The porosity corresponded to trabecular metal, striations — 0.45, pores size —100–200 microns. Study and control components were implanted in the identical conditions into the corresponding anatomical sites. Postoperative AP and lateral roentgenograms of knee joints were performed for all animals. Morphological research was conducted on day 60 after the implantation and strength properties were studied at day 90 after the implantation.Results. The authors observed bony ingrowth into implant pores with minimal volume of fibrous tissue, a distinct connective integration was reported represented by a dense fibrous tissue in the pores of components implanted into the muscular tissue. Testing of fixation strength of the study implants demonstrated a clearly superior strength of soft and bone tissue integration into the experimental mesh implants produced using additive technologies.Актуальность. При ревизионном эндопротезировании крупных суставов как правило возникает необходимость замещения костных дефектов сложной геометрической формы с одновременным воссозданием опоры и возможностью интеграции окружающих мышечных и сухожильных структур в имплантат, что необходимо для полноценного восстановления функции сустава.Цель — изучить в эксперименте процессы интеграции мышечной и костной тканей, а также сухожильно-связочного аппарата в титановые пористые материалы.Материал и методы. В эксперименте in vivo 6 кроликам породы шиншилла был создан стандартизированный дефект костной ткани в точке прикрепления сухожилия связки надколенника, а также зона расслоения мышечной ткани широчайшей мышцы спины. У каждого животного использовали оба коленных сустава и обе широчайшие мышцы спины. Опытную группу исследования составили титановые образцы с пространственной сетчатой структурой, контрольную — цельные титановые образцы со стандартной пористостью. Титановые образцы были получены путем аддитивных технологий с предварительным прототипированием. Пористость соответствовала трабекулярному металлу, страты — 0,45, размер пор 100–200 мкм. Образцы исследуемых материалов были имплантированы в одинаковых условиях в соответствующие анатомические участки. Морфологические исследования были выполнены на 60-е сутки после оперативного лечения, исследования прочностных свойств — на 90-е сутки.Результаты. Выявлено прорастание костной ткани в поры имплантатов с минимальным количеством фиброзной ткани, обнаружена отчетливая соединительнотканная интеграция, представленная плотной фиброзной тканью в порах материала, имплантированного в мышечную ткань. При исследовании прочности фиксации тестируемых образцов отчетливо демонстрируется превосходящая прочность интеграции мягких и костной тканей в опытные сетчатые имплантаты, изготовленные с помощью аддитивных технологий.Заключение. Исследование открывает широкие перспективы применения высокопористых титановых имплантатов, изготовленных методом 3D-печати, для восстановительной и ревизионной хирургии в отношении как замещения костных дефектов, так и восстановления поврежденных мышц

On the covariant quantization of tensionless bosonic strings in AdS spacetime

The covariant quantization of the tensionless free bosonic (open and closed) strings in AdS spaces is obtained. This is done by representing the AdS space as an hyperboloid in a flat auxiliary space and by studying the resulting string constrained hamiltonian system in the tensionless limit. It turns out that the constraint algebra simplifies in the tensionless case in such a way that the closed BRST quantization can be formulated and the theory admits then an explicit covariant quantization scheme. This holds for any value of the dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde