The Bonebridge system – Our clinical experience /Case report/

Introduction: Bone conduction implants are a standard treatment option for patients with conductive or mixed, hearing loss. The Bonebridge system was introduced by MED-EL in 2012, and two years after its debut, it was used in more than 200 centers worldwide (6). For the first time the Bonebridge system was implanted in Bulgaria in 2015 by associated professor P. Rouev. The main audiological criteria for placement is conductive hearing loss, which is caused by atresia of the auditory canal or diseases of the middle ear with preserved bone conduction (below 45 dB), as well as unilateral hearing loss above 70 dB (contralateral hearing loss not more than 20 dB). The system does not penetrate the skin and consists of an internal part - an implant, which is placed completely under the skin, and an external part - a processor. The acoustic signal from the environment is transformed into mechanical vibrations that are transmitted to the mastoid bone. The expected results are an improved hearing threshold and better hearing in noisy environments.Methods: Our clinical experience with the Bonebridge system is based on three operated patients aged between 56 and 73 years. All three patients had evidence of bilateral conductive hearing loss. Here we present one of these cases.Results: Test results showed significant improvement in hearing sensitivity especially in frequencies round 1000 Hz.Conclusions: Bone conduction implants such as the Bonebridge system are an excellent treatment option for patients with bilateral conductive deafness. Bonebridge has good hearing results, relative simplicity, and low rate of complications. Experience has shown that the Bonebridge system is easy to use and highly reliable. The use of Bonebridge conduction implant system leads to a significant improvement in the quality of life

Generalising some results about right-angled Artin groups to graph products of groups

We prove three results about the graph product G=\G(\Gamma;G_v, v \in V(\Gamma)) of groups $G_v$ over a graph $\Gamma$. The first result generalises a result of Servatius, Droms and Servatius, proved by them for right-angled Artin groups; we prove a necessary and sufficient condition on a finite graph $\Gamma$ for the kernel of the map from $G$ to the associated direct product to be free (one part of this result already follows from a result in S. Kim's Ph.D. thesis). The second result generalises a result of Hermiller and Sunic, again from right-angled Artin groups; we prove that for a graph $\Gamma$ with finite chromatic number, $G$ has a series in which every factor is a free product of vertex groups. The third result provides an alternative proof of a theorem due to Meier, which provides necessary and sufficient conditions on a finite graph $\Gamma$ for $G$ to be hyperbolic

The Identity Correspondence Problem and its Applications

In this paper we study several closely related fundamental problems for words and matrices. First, we introduce the Identity Correspondence Problem (ICP): whether a finite set of pairs of words (over a group alphabet) can generate an identity pair by a sequence of concatenations. We prove that ICP is undecidable by a reduction of Post's Correspondence Problem via several new encoding techniques. In the second part of the paper we use ICP to answer a long standing open problem concerning matrix semigroups: "Is it decidable for a finitely generated semigroup S of square integral matrices whether or not the identity matrix belongs to S?". We show that the problem is undecidable starting from dimension four even when the number of matrices in the generator is 48. From this fact, we can immediately derive that the fundamental problem of whether a finite set of matrices generates a group is also undecidable. We also answer several question for matrices over different number fields. Apart from the application to matrix problems, we believe that the Identity Correspondence Problem will also be useful in identifying new areas of undecidable problems in abstract algebra, computational questions in logic and combinatorics on words.Comment: We have made some proofs clearer and fixed an important typo from the published journal version of this article, see footnote 3 on page 1

CALCULATION METHODS OF OPTIMIZATION OF RADIATION PROTECTION CONTAINERS FOR STORAGE SOLID RADIOACTIVE WASTE

The report contains an analysis of the effectiveness of the protection from gamma-radiation steel canisters and protected by lead and placed in a container of NZK-I. the course work has been applied to the calculation of Monte Carlo. The results of calculations made recommendations aimed at enhancing the protection and reducing its material consumption.В докладе содержится анализ эффективности защиты от гамма-излучения стальных пеналов с РАО, окруженных свинцовой защитой и помещенных в контейнер НЗК-I. В ходе работы был применен расчет по методу Монте-Карло. По результатам расчетов вынесены рекомендации, направленные на повышение эффективности защиты и уменьшение ее материалоемкости

Supplementation with Lactobacillus plantarum WCFS1 Prevents Decline of Mucus Barrier in Colon of Accelerated Aging Ercc1−/Δ7 Mice

textabstractAlthough it is clear that probiotics improve intestinal barrier function, little is known about the effects of probiotics on the aging intestine. We investigated effects of 10-week bacterial supplementation of Lactobacillus plantarum WCFS1, Lactobacillus casei BL23, or Bifidobacterium breve DSM20213 on gut barrier and immunity in 16-week-old accelerated aging Ercc1-/Δ7 mice, which have a median lifespan of ~20 weeks, and their wild-type littermates. The colonic barrier in Ercc1-/Δ7 mice was characterized by a thin (< 10 μm) mucus layer. L. plantarum prevented this decline in mucus integrity in Ercc1-/Δ7 mice, whereas B. breve exacerbated it. Bacterial supplementations affected the expression of immune-related genes, including Toll-like receptor 4. Regulatory T cell frequencies were increased in the mesenteric lymph nodes of L. plantarum- and L. casei-treated Ercc1-/Δ7 mice. L. plantarum- and L. casei-treated Ercc1-/Δ7 mice showed increased specific antibody production in a T cell-dependent immune response in vivo. By contrast, the effects of bacterial supplementation on wild-type control mice were negligible. Thus, supplementation with L. plantarum - but not with L. casei and B. breve - prevented the decline in the mucus barrier in Ercc1-/Δ7 mice. Our data indicate that age is an important factor influencing beneficial or detrimental effects of candidate probiotics. These findings also highlight the need for caution in translating beneficial effects of probiotics observed in young animals or humans to the elderly

Numerical simulation of atmospheric-pressure 200 kHz / 13.56 MHz dual-frequency dielectric barrier discharges

A one-dimensional drift-diffusion model is used to study atmospheric-pressure dual frequency (DF) dielectric barrier discharges in argon using the plasma modelling platform PLASIMO. The simulation exhibits an excellent agreement with the experimental results and gives insight into the DF plasma dynamics e.g. the electric field, the sheath edge profiles, the ionization/excitation rate and the electron energy distribution function (EEDF) profiles. The results indicate that due to the RF oscillation, the electric field, the sheath edge and thus the ionization/excitation are temporally modulated. As a result, the plasma conductivity is enhanced as the plasma density is higher. The discharge development is slowed down with a lower current amplitude and a longer duration. The time-averaged sheath is getting thinner with a more pronounced ionization rate and a longer contacting time near the substrate, which could help to improve the efficiency of plasma-assisted surface processing. In addition, the DF excitation exhibits a capability of modifying the EEDF profiles and controlling the plasma chemical kinetics, which can be applied to the other relevant fields e.g. gas phase chemical conversion.</p