Five-Year Experience In Surgical Treatment Of Temporal Bone Paragangliomas

The article describes our five-year experience in the surgical treatment of temporal bone paragangliomas. Considering our experience, the surgical treatment of patients with different types of paragangliomas based on a detailed study of the CT scan and MRI data using the preoperative selective embolization of tumor-feeding vessels and the navigation system intraoperatively as well as the endoscopy assistance allows total removing of the tumor with minimal damaging of the vital structures of the lateral skull base

Strictly and asymptotically scale-invariant probabilistic models of NN correlated binary random variables having {\em q}--Gaussians as N→∞N\to \infty limiting distributions

In order to physically enlighten the relationship between {\it $q$--independence} and {\it scale-invariance}, we introduce three types of asymptotically scale-invariant probabilistic models with binary random variables, namely (i) a family, characterized by an index $\nu=1,2,3,...$, unifying the Leibnitz triangle ($\nu=1$) and the case of independent variables ($\nu\to\infty$); (ii) two slightly different discretizations of $q$--Gaussians; (iii) a special family, characterized by the parameter $\chi$, which generalizes the usual case of independent variables (recovered for $\chi=1/2$). Models (i) and (iii) are in fact strictly scale-invariant. For models (i), we analytically show that the $N \to\infty$ probability distribution is a $q$--Gaussian with $q=(\nu -2)/(\nu-1)$. Models (ii) approach $q$--Gaussians by construction, and we numerically show that they do so with asymptotic scale-invariance. Models (iii), like two other strictly scale-invariant models recently discussed by Hilhorst and Schehr (2007), approach instead limiting distributions which are {\it not} $q$--Gaussians. The scenario which emerges is that asymptotic (or even strict) scale-invariance is not sufficient but it might be necessary for having strict (or asymptotic) $q$--independence, which, in turn, mandates $q$--Gaussian attractors.Comment: The present version is accepted for publication in JSTA

Black hole thermodynamical entropy

As early as 1902, Gibbs pointed out that systems whose partition function diverges, e.g. gravitation, lie outside the validity of the Boltzmann-Gibbs (BG) theory. Consistently, since the pioneering Bekenstein-Hawking results, physically meaningful evidence (e.g., the holographic principle) has accumulated that the BG entropy $S_{BG}$ of a $(3+1)$ black hole is proportional to its area $L^2$ ($L$ being a characteristic linear length), and not to its volume $L^3$. Similarly it exists the \emph{area law}, so named because, for a wide class of strongly quantum-entangled $d$-dimensional systems, $S_{BG}$ is proportional to $\ln L$ if $d=1$, and to $L^{d-1}$ if $d>1$, instead of being proportional to $L^d$ ($d \ge 1$). These results violate the extensivity of the thermodynamical entropy of a $d$-dimensional system. This thermodynamical inconsistency disappears if we realize that the thermodynamical entropy of such nonstandard systems is \emph{not} to be identified with the BG {\it additive} entropy but with appropriately generalized {\it nonadditive} entropies. Indeed, the celebrated usefulness of the BG entropy is founded on hypothesis such as relatively weak probabilistic correlations (and their connections to ergodicity, which by no means can be assumed as a general rule of nature). Here we introduce a generalized entropy which, for the Schwarzschild black hole and the area law, can solve the thermodynamic puzzle.Comment: 7 pages, 2 figures. Accepted for publication in EPJ

Limit distributions of scale-invariant probabilistic models of correlated random variables with the q-Gaussian as an explicit example

Extremization of the Boltzmann-Gibbs (BG) entropy under appropriate norm and width constraints yields the Gaussian distribution. Also, the basic solutions of the standard Fokker-Planck (FP) equation (related to the Langevin equation with additive noise), as well as the Central Limit Theorem attractors, are Gaussians. The simplest stochastic model with such features is N to infinity independent binary random variables, as first proved by de Moivre and Laplace. What happens for strongly correlated random variables? Such correlations are often present in physical situations as e.g. systems with long range interactions or memory. Frequently q-Gaussians become observed. This is typically so if the Langevin equation includes multiplicative noise, or the FP equation to be nonlinear. Scale-invariance, i.e. exchangeable binary stochastic processes, allow a systematical analysis of the relation between correlations and non-Gaussian distributions. In particular, a generalized stochastic model yielding q-Gaussians for all q (including q>1) was missing. This is achieved here by using the Laplace-de Finetti representation theorem, which embodies strict scale-invariance of interchangeable random variables. We demonstrate that strict scale invariance together with q-Gaussianity mandates the associated extensive entropy to be BG.Comment: 6 pages, 1 fig, to appear in EPJ

Theoretical Foundations of the Principles of Increasing the Effectiveness of Teaching Information and Communication Technologies Based on Didactic Laws

The article examines the subject, functions and main categories of didactics. The essence of the ICT process. Description of educational processes, their relationship in the educational process. The effectiveness of pedagogical and information technologies depends on compliance with the laws of education, creates a wide range of opportunities for the creation and implementation of a system of objective assessment of the quality of the educational process and training

Difficult cases of cochlear implantation

Background: In the recent  years, there  is a tendency to extend  the  indications  to cochlear implantation in patients  with inner and middle ear malformations, cochlea  ossificans and  Meniere's disease. In otosurgical practice, the cases are not uncommon when  cochlear  implantation is difficult after previous canal wall down mastoidectomy due to chronic suppurative otitis media. Aim: To improve postoperative auditory performance of patients  with profound  sensorineural  hearing loss (deafness), complicated  by the inner or middle ear disorders, through the optimization of cochlear implantation surgical technique. Materials and methods: We analyzed 42 patients  with profound  sensorineural  hearing  loss who underwent  cochlear  implantation, 12 of them  having cochlea  ossification  after  meningitis  (group  1), 19,  with  inner  ear  malformations   (group  2),  9, had underwent canal wall down mastoidectomy (group 3) and 2, with Meniere's disease (group 4). Surgical  techniques  varied  depending  on  the type of disorder. In all patients, implant  telemetry and  evoked  stapes  reflex registration  (if stapedium muscle was present) were performed. Postoperatively the mastoid cavity was controlled by  otomicroscopy. Results: Stapes  reflex were obtained in 8 patients  from group  1. Number of from group 3 in whom of the proposed cochlear implantation technique was used, no long-term relapses of chronic suppurative otitis media were observed, the mastoid cavity could be visualized very well and graft survival was excellent. No cases of electrode array extrusion or protrusion were registered. Patients  with  Meniere's  disease  and bilateral  sensorineural  hearing  loss who  underwent  simultaneous  operations  (endolymphatic sac drainage  and cochlear implantation)  showed satisfactory results of audioverbal  rehabilitation and a marked reduction  of vestibular symptoms. Conclusion: Surgical techniques proposed in this study  allow for insertion  of maximal  electrode numbers  into the spiral canal of a malformed and ossified cochlea. Formation  of bone  tunnels  for the active electrode  in the burred  cavity and its covering with autocartilage helps to prevent  any protrusion  and displacement of the electrode  in patients   who  had  previously  underwent canal wall down mastoidectomy. Simultaneous cochlear implantation and endolymphatic sac drainage is also considered  to be an adequate approach  to treatment of patients  with late  stage  Meniere's disease with profound bilateral sensorineural hearing loss

Management and surgical outcomes in patients with chronic suppurative otitis media

Background: Reconstruction of the ossicular chain is performed in 70-90% of tympanoplastic interventions. A cholesteatoma in chronic suppurative otitis media is diagnosed in 24-63% cases, irrespective of localization of the eardrum perforation. Persistently good outcomes after radical mastoidectomy is obtained only in 65 to 66% of patients, and the proportion of unsatisfactory results remains to be rather high (10 to 15%). Aim: To analyze the effectiveness of surgical treatment of patients with chronic suppurative otitis media, operated in a single clinical center from 2014 to 2016. Materials and methods: A total of 212 patients (233 ears) with chronic suppurative otitis media patients, who underwent surgery, were included in this study. The effectiveness of surgical interventions were assessed as short-term (up to 3 months post-operatively) and long-term (6 to 12 months) anatomical and functional outcomes. The anatomical results were considered satisfactory if there was a well-formed mobile neotympanic membrane, air tympanic cavity and dry postoperative cavity. Pure tone audiograms were analyzed to evaluate the functional results. Results: Satisfactory anatomical results were obtained in 93.5% of patients with the safe type suppurative otitis, 88.9% of patients with the unsafe type and 91.2% of patients after a revision surgery. Displacement of total ossicular prosthe-ses was the main cause of poor functional results. The most common causes of unsatisfactory anatomical results were perforation (14 cases), cholesteatoma recurrence (2 cases) and lateralization of the neotympanic membrane (2 cases). Discussion and conclusion: Formation of a reliable sound conducting system with ossicular prostheses allows for persistent improvement of hearing. Various surgical techniques, such as extended posterior tympanotomy, endoscopic assistance, provide a good effect with the removal of non-aggressive cholesteatoma while preserving the bone structures, which are not involved in the disease. A complete removal of an advanced aggressive cholesteatoma with the opening of the temporal bone cell system ensures good functional and anatomical outcomes, makes it possible to prevent the spread of the pathological process and development of intracranial complications