Nonequilibrium, thermostats and thermodynamic limit

The relation between thermostats of "isoenergetic" and "frictionless" kind is studied and their equivalence in the thermodynamic limit is proved in space dimension $d=1,2$ and, for special geometries, $d=3$.Comment: 22 pages PRA 2-columns format v3: Typos corrected as acknowledge

Identification of a regulated pathway for nuclear pre-mRNA turnover

We have identified a nuclear pathway that rapidly degrades unspliced pre-mRNAs in yeast. This involves 3′→5′ degradation by the exosome complex and 5′→3′ degradation by the exonuclease Rat1p. 3′→5′ degradation is normally the major pathway and is regulated in response to carbon source. Inhibition of pre-mRNA degradation resulted in increased levels of pre-mRNAs and spliced mRNAs. When splicing was inhibited by mutation of a splicing factor, inhibition of turnover resulted in 20- to 50-fold accumulation of pre-mRNAs, accompanied by increased mRNA production. Splicing of a reporter construct with a 3′ splice site mutation was also increased on inhibition of turnover, showing competition between degradation and splicing. We propose that nuclear pre-mRNA turnover represents a novel step in the regulation of gene expression

Current reservoirs in the simple exclusion process

We consider the symmetric simple exclusion process in the interval $[-N,N]$ with additional birth and death processes respectively on $(N-K,N]$, $K>0$, and $[-N,-N+K)$. The exclusion is speeded up by a factor $N^2$, births and deaths by a factor $N$. Assuming propagation of chaos (a property proved in a companion paper "Truncated correlations in the stirring process with births and deaths") we prove convergence in the limit $N\to \infty$ to the linear heat equation with Dirichlet condition on the boundaries; the boundary conditions however are not known a priori, they are obtained by solving a non linear equation. The model simulates mass transport with current reservoirs at the boundaries and the Fourier law is proved to hold

Endoscopic-assisted Cochlear Implantation in Children with malformed ears

Objective: Complex middle and inner ear malformations are considered an important limitation for cochlear implant (CI) with traditional microscopic techniques. The aim of the present study is to describe the results of the endoscopic-assisted CI procedure in children with malformed ears. Study design: Case series with chart review of consecutive patients. Setting: Two tertiary referral centers: University Hospital of Verona and University Hospital of Modena, Italy. Subjects and methods: In total, 25 children underwent endoscopic-assisted cochlear implantation between January 2013 and January 2018. The audiologic and neuroradiologic assessment showed profound hearing loss and malformation of the middle and inner ear in all children. A complete review of anatomic features, surgical results, and audiologic outcomes was performed. The surgical technique is described step-by-step, and the outcomes are detailed. Results: All patients (mean age, 3.6 years; range, 2.8-9 years) underwent a transattical/endoscopic-assisted CI procedure. All children showed varying degrees of auditory benefit, as measured by routine audiometry, speech perception tests, and Categories of Auditory Performance scores (mean, 6). No immediate or late postoperative complications were noted. Conclusion: The endoscopic-assisted approach proved to be successful in cochlear implantation. The direct visualization and magnification allow (1) exploration of the tympanic cavity; (2) confirmation of all anatomic features, with strict control of the course of the facial nerve, round window area, and inner ear; and (3) performance of the cochleostomy with adequate insertion of the array

Discovering middle ear anatomy by transcanal endoscopic ear surgery: A dissection manual

The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal approach to the middle ear is a minimally invasive technique sparing the bone and mucosa of the mastoid bone, since the middle ear is accessed through the external auditory canal. This emerging method has several advantages over the traditional (microscopic) approaches to the middle ear such as the panoramic wide-angle views of the anatomy, the possibility to approach and magnify tiny structures, and the possibility of looking around the corner using angled endoscopes. The cadaveric dissection method presented here consists of an overview on the technical requirements and a precise description of a step-by-step protocol to discover the anatomy of the middle ear. Each step and anatomical structure is carefully described in order to provide a comprehensive guide to endoscopic ear anatomy. In our opinion, this is particularly important to any novice in endoscopic ear surgery as it provides thorough anatomical knowledge and may improve surgical skills

Role of endoscopy in lateral skull base approaches to the petrous apex

Objective: The aim of this article is to study the role and advantages of combined microscopic/endoscopic procedures or exclusive endoscopic approaches in the treatment of petrous apex pathologies. Methods: The study was designed as a retrospective case series analysis. We included patients affected by pathologies of the petrous apex, who underwent microscopic/endoscopic-assisted or exclusive endoscopic procedures. Patient and pathology characteristics and surgical data (focusing on the involvement of the internal carotid artery (ICA) and facial nerve by the disease) were collected. Residual disease, detected through the endoscopic check, and the feasibility of endoscopic residual tumor removal were also evaluated. Finally, facial nerve and hearing functions were assessed pre- and postoperatively. Results: The records of 75 patients undergoing lateral skull base surgery for petrous apex lesions, from May 2009 to March 2019, were collected. In 17 out of 75 patients, an exclusive endoscopic procedure was possible. The remaining 58 patients underwent a combined microscopic/endoscopic approach. In 15 cases, residual disease was found and removed endoscopically at the end of the microscopic procedure; in eight cases, the residual disease was medial and/or inferior to the horizontal segment of the ICA, while in two cases, it was located in the fundus of the internal auditory canal. In five cases, it involved the labyrinthine segment of the facial nerve. Conclusion: Petrous apex surgery remains a traditional microscopic-based surgery, but the recent advent of endoscopic surgery has permitted an improvement in radicality minimizing the manipulation of neurovascular structures

Surgical multidisciplinary approach of orbital complications of sinonasal inflammatory disorders

Orbital infection complicating sinonasal inflammatory disorders may lead to serious sequelae, including blindness and death, if untreated. Communication between the otorhinolaryngologist, neuroradiologist, ophtalmologist, neurosurgeon and maxillo-facial surgeon is critical and time-sensitive for a successful treatment. The large majority of pre-septal cellulitis cases resolves after broad-spectrum antibiotic therapy. Also orbital cellulitis has been found responsive to pharmacological approach in most cases. The management of the subperiosteal abscess (SPA) is more controversial. An aggressive surgical approach is always recommended also in case of cavernous sinus thrombosis. In cases of surgical indication, debate is still open on the timing and the approach (endoscopic or external). The surgeon should be prepared to convert an endoscopic approach to an external one if needed and this should be included in the informed consent. Decompression of one or more orbital walls may be necessary if orbital pressure remains elevated. Immediate surgery is indicated in children with large SPA or orbital abscesses (OA), or in immune-compromised patients. Moreover, any worsening in the ophthalmological function must be carefully considered as a landmark in candidacy to surgery

Transnasal endoscopic removal of malformation of the odontoid process in a patient with type I Arnold-Chiari malformation: a case report

The endoscopic endonasal approach is emerging as a feasible alternative to the trans-oral route for the resection of the odontoid process, when the latter produces a compression of the brainstem and cervicomedullary junction. This type of approach has some advantages, such as excellent pre-vertebral exposure of the cranio-vertebral junction in patients with small oral cavities and the possibility to avoid the use of mouth retractors. A typical case of a 24-year-old male patient with a previous diagnosis of type I Arnold-Chiari Malformation, suffering from a posterior dislocation of the odontoid process causing severe anterior compression of the brainstem, is presented to stress the potential of this technique. Trans-nasal endoscopic removal of the odontoid process was performed and resolution of the ventral compression of the brainstem was achieved. This report demonstrates that in selected cases, an endoscopic endonasal approach should now be considered an excellent alternative to the traditional trans-oral approach

Entropy-driven cutoff phenomena

In this paper we present, in the context of Diaconis' paradigm, a general method to detect the cutoff phenomenon. We use this method to prove cutoff in a variety of models, some already known and others not yet appeared in literature, including a chain which is non-reversible w.r.t. its stationary measure. All the given examples clearly indicate that a drift towards the opportune quantiles of the stationary measure could be held responsible for this phenomenon. In the case of birth- and-death chains this mechanism is fairly well understood; our work is an effort to generalize this picture to more general systems, such as systems having stationary measure spread over the whole state space or systems in which the study of the cutoff may not be reduced to a one-dimensional problem. In those situations the drift may be looked for by means of a suitable partitioning of the state space into classes; using a statistical mechanics language it is then possible to set up a kind of energy-entropy competition between the weight and the size of the classes. Under the lens of this partitioning one can focus the mentioned drift and prove cutoff with relative ease.Comment: 40 pages, 1 figur