On one loop corrections in higher spin gravity

We propose an approach to compute one-loop corrections to the four-point amplitude in the higher spin gravities that are holographically dual to free $O(N)$, $U(N)$ and $USp(N)$ vector models. We compute the double-particle cut of one-loop diagrams by expressing them in terms of tree level four-point amplitudes. We then discuss how the remaining contributions to the complete one-loop diagram can be computed. With certain assumptions we find nontrivial evidence for the shift in the identification of the bulk coupling constant and $1/N$ in accordance with the previously established result for the vacuum energy.Comment: 25 pages, several figures; few comments added, the discussion of the incompleteness of Vasiliev equations reduced; replaced with the published versio

Non-abelian cubic vertices for higher-spin fields in anti-de Sitter space

We use the Fradkin-Vasiliev procedure to construct the full set of non-abelian cubic vertices for totally symmetric higher spin gauge fields in anti-de Sitter space. The number of such vertices is given by a certain tensor-product multiplicity. We discuss the one-to-one relation between our result and the list of non-abelian gauge deformations in flat space obtained elsewhere via the cohomological approach. We comment about the uniqueness of Vasiliev's simplest higher-spin algebra in relation with the (non)associativity properties of the gauge algebras that we classified. The gravitational interactions for (partially)-massless (mixed)-symmetry fields are also discussed. We also argue that those mixed-symmetry and/or partially-massless fields that are described by one-form connections within the frame-like approach can have nonabelian interactions among themselves and again the number of nonabelian vertices should be given by tensor product multiplicities.Comment: 30 pages, v2: minor corrections, reference adde

On the uniqueness of higher-spin symmetries in AdS and CFT

We study the uniqueness of higher-spin algebras which are at the core of higher-spin theories in AdS and of CFTs with exact higher-spin symmetry, i.e. conserved tensors of rank greater than two. The Jacobi identity for the gauge algebra is the simplest consistency test that appears at the quartic order for a gauge theory. Similarly, the algebra of charges in a CFT must also obey the Jacobi identity. These algebras are essentially the same. Solving the Jacobi identity under some simplifying assumptions spelled out, we obtain that the Eastwood-Vasiliev algebra is the unique solution for d=4 and d>6. In 5d there is a one-parameter family of algebras that was known before. In particular, we show that the introduction of a single higher-spin gauge field/current automatically requires the infinite tower of higher-spin gauge fields/currents. The result implies that from all the admissible non-Abelian cubic vertices in AdS(d), that have been recently classified for totally symmetric higher-spin gauge fields, only one vertex can pass the Jacobi consistency test. This cubic vertex is associated with a gauge deformation that is the germ of the Eastwood-Vasiliev's higher-spin algebra.Comment: 37 pages; refs added, proof of uniquiness was improve

Gapful electrons in a vortex core in granular superconductors

We calculate the quasiparticle density of states (DoS) inside the vortex core in a granular superconductor, generalizing the classical solution applicable for dirty superconductors. A discrete version of the Usadel equation for a vortex is derived and solved numerically for a broad range of parameters. Electron DoS is found to be gapful when the vortex size $\xi$ becomes comparable to the distance between neighboring grains $l$. Minigap magnitude $E_g$ grows from zero at $\xi \approx 1.4 l$ to third of superconducting gap $\Delta_0$ at $\xi \approx 0.5 l$. The absence of low-energy excitations is the main ingredient needed to understand strong suppression of microwave dissipation recently observed in a mixed state of granular Al

Instability of the Knee Joint Before and After Reconstruction of the Anterior Cruciate Ligament According to the Questionnaire

Background: The instability of the knee joint after a rupture of the anterior cruciate ligament in recent decades has acquired the character of a meme among Russian orthopedists with a very wide use and meaning. Aim: In this study, we tried to find out how often the phenomenon of instability occurs and how it can be associated with joint injury. Methods: The method of questioning, collecting anamnesis in patients at the primary orthopedic appointment and in patients after surgical reconstruction by the method of questioning was used. Results: The data collected in 433 patients with a verified rupture of the anterior cruciate ligament showed that 77% experienced a feeling of instability in the knee joint, and 19% did not experience them at all. Arthroscopic reconstruction was performed in 297 patients, 71 of them were surveyed. The period of time from surgery to questioning was 6.5 years on average. Not all patients can note the moment of injury. Even if there was an injury to the knee joint, 10% of patients do not note the development of instability immediately after injury. The duration of the sensation of instability in the knee joint after injury varies from one week to a year or more. The very moment of joint instability is accompanied by pain in more than half of the cases. At the same time, 12% of the respondents had no pain. A third of the respondents had never noted episodes of instability in the knee joint before surgical reconstruction. But 11% had such episodes daily. In the postoperative period, 27% note the recurrence of joint instability at different times. Conclusions: Thus, an ACL tear does not equal knee instability. Instability is not a condition, but a short-term episode that occurs during the period of support and leads to buckling of the limb

Targeted training of the function of walking according to the stance and single support phase in patients in the early recovery period of cerebral stroke

Background: The phases of support and single support on a limb are significant basic parameters of walking (phase of support means the whole limb support time, while the phase of single support is when only one limb is on the ground). Both can be used as targets for biofeedback training. Aim: to investigate the effectiveness of both target parameters for training the function of walking with biofeedback in patients in the early recovery period of cerebral stroke. Methods: The study involved 40 patients, 20 in each group, who underwent a training course to harmonize walking: the first group for the period of support, and the second group for the period of single support. The control group of healthy people also consisted of 20 people. We studied the spatiotemporal parameters of walking at an arbitrary pace at the beginning and after the end of the training course, as well as classical clinical scales. The treadmill training consisted of 10 sessions. Results: The clinical and biomechanical parameters of walking changed their values in the direction of a significant improvement in the performance. At the same time, the biomechanical parameters of the second group indicated a more severe functional state before the start of the treatment, with the same clinical parameters according to the Barthel scale, Rivermead Mobility Index, modified Rankin scale, rehabilitation routing scale, and manual muscle testing. In the first group, indirect data were obtained on the possible effect of the target indicator on the training and direct data on its effect on the function of a healthy limb, which also allows increasing the load on the paretic one. In the second group, there were no reliable data on the effect of biofeedback training on the functional outcome. Conclusion: The conducted study showed that the classical clinical assessment of the patient's condition may not correspond to the instrumental functional study of walking. When using the support period as the training target parameter, indirect evidence was obtained that such a training is effective

Хронические нарушения сознания: клинические рекомендации Общероссийской общественной организации «Федерация анестезиологов и реаниматологов»

Хронические нарушения сознания (ХНС) представляют собой синдромы тяжелого поражения центральной нервной системы, приводящие к длительной грубой инвалидизации и требующие значительных усилий по лечению и реабилитации, которые ложатся на медицинские учреждения и на плечи близких пациентов. ХНС развиваются у пациентов после комы и характеризуются наличием бодрствования при полном или практически полном отсутствии признаков осознанного поведения. К ХНС относятся вегетативное состояние (ВС) и состояние минимального сознания (СМС). Также для описания начальных стадий этих состояний используется термин «продленное нарушение сознания» (ПНС). Отдельно выделяют выход из СМС — состояние, которое формируется по мере восстановления когнитивных функций. Диагностика ХНС основывается на многократном структурированном клиническом осмотре с применением специализированных шкал при условии исключения обратимых причин нарушения сознания. Лечение пациентов с ХНС включает в себя поддержание жизненно важных функций, обеспечение оптимального питания и борьбу с типичными осложнениями и сопутствующими состояниями (пролежни, спастичность, боль, пароксизмальная симпатическая гиперактивность и др.). У пациентов с ХНС должна проводиться реабилитация с участием мультидисциплинарной реабилитационной команды в объеме, который определяется проблемами и возможностями конкретного пациента. Наиболее эффективной реабилитация является при условии ее раннего начала. На данный момент однозначных доказательств эффективности каких-либо специфических методов, направленных на восстановление сознания, не получено; изучается ряд соответствующих фармакологических и нефармакологических вмешательств, обязательным условием применения которых является максимально возможная коррекция соматических проблем пациента. Важную роль в ведении пациентов с ХНС играет вовлечение близких пациента, которые, в свою очередь, нуждаются в получении объективной практической информации о состоянии своего родственника и о направлениях реабилитации, а также в психологической помощи

Experimental Study of Military Crawl as a Special Type of Human Quadripedal Automatic Locomotion

The biomechanics of military crawl locomotion is poorly covered in scientific literature so far. Crawl locomotion may be used as a testing procedure which allows for the detection of not only obvious, but also hidden locomotor dysfunctions. The aim of the study was to investigate the biomechanics of crawling among healthy adult participants. Eight healthy adults aged 15–31 (four women and four men) were examined by means of a 3D kinematic analysis with Optitrack optical motion-capture system which consists of 12 Flex 13 cameras. The movements of the shoulder, elbow, knee, and hip joints were recorded. A person was asked to crawl 4 m on his/her belly. The obtained results including space-time data let us characterize military crawling in terms of pelvic and lower limb motions as a movement similar to walking but at a more primitive level. Progressive and propulsive motions are characterized as normal; additional right–left side motions—with high degree of reciprocity. It was found that variability of the left-side motions is significantly lower than that of the right side (Z = 4.49, p < 0.0001). The given normative data may be used as a standard to estimate the test results for patients with various pathologies of motor control (ataxia, abasia, etc.)

Biomechanical Changes in Gait Patterns of Patients with Grade II Medial Gonarthritis

Deforming osteoarthritis (OA) of the knee is a progressive disease associated with pain and compromised function of the joint. Typical biomechanical modifications in the gait of subjects with medial knee OA are characterized by decreased gait speed and overload on the affected limb. The borderline stage for conservative versus surgical management is Grade II OA. The aim of this research was to study preoperatively the specific features of gait, knee, and hip function in patients with Grade II medial OA. We examined 26 patients with Grade II unilateral gonarthritis with varus deformity and 20 healthy adults. Biomechanical parameters of gait were recorded using an inertial sensor system. The gait cycle (GC) slightly increased both for the affected and for the intact limb. The hip joint movements showed significant symmetrical reduction in the first flexion amplitude, as well as a symmetrical delay in full hip extension at the end of the stance phase. In the knee, the first flexion amplitude was significantly reduced on the affected side compared to healthy control. The extension amplitude in the single support phase was significantly increased in both the affected and the intact lower limbs. The swing amplitude was significantly reduced on the affected side. On the affected side, the changes were more pronounced, both in incidence and in severity. The affected knee showed a syndrome of three reduced amplitudes. In patients, walking is characterized by several groups of symptoms: those of unloading of the affected limb, those of limiting the load on the affected joint and the musculoskeletal system as a whole, and those of gait harmonization. The symptoms of unloading the affected side and those of harmonization are the common symptoms of adaptation, typical for several pathological conditions with a relatively preserved function. The intensity of the observed symptoms can help assess changes in the subject’s functional condition over time and during the treatment