Understanding expertise in surgical gesture by means of Hidden Markov Models

Minimally invasive surgery (MIS) has became very widespread in the last ten years. Due to the difficulties encountered by the surgeons to learn and manage this technique, a huge importance has the improvement of training procedures, the improvement of surgical instrumentation and the robotic automation of surgical gesture. All these purposes require the analysis of surgical performance with the aim to understand it and to define what is expertise in surgical gesture. In this paper for the first time the Hidden Markov Models (HMMs) are used as a tool for the understanding of surgical performance and of the human factors that characterize it. In our experiments we used position data concerning the tools movements during exercises performed on a surgical simulator. Using Hidden Markov theory, we create a model of the expert surgeon performance able to evaluate surgical capability and to distinguish between expert and non-expert surgeons. By analyzing the trained model of the expert surgeon performance we show that it is possible to deduce information about features characterizing the surgical expertise

Femoral revision with the modular ZMR stem. Clinical and x-rays results at medium term follow-up

A retrospective review was conducted to evaluate the medium-term results of the ZMR modular revision taper stem. From March 1999 to December 2002, 65 consecutive hip revision surgeries were performed mostly for aseptic loosening. Femoral bone stock defects were classified according to AAOS\u2019s criteria and consisted mainly in type II and type III. A Wagner osteotomy was performed in 25 cases to remove primary implants that were cemented in 35 cases. Mean post-operative follow-up was 69 months (range, 36 to 91months). Clinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 42 points preoperatively to 81 points postoperatively, while the x-ray examination did show a satisfactory distal integration of the stem in all cases and satisfactory reconstitution of the femoral bone stock in 47% of cases. The average subsidence of the stem at follow-up was under one millimeter. According to the data leg length discrepancy exceeding 15 millimeters caused significantly higher functional impairment and more pain

Treatment of periprosthetic femoral fractures with distal fixation modular revision stems

Background Late periprosthetic fractures of the femur are the third most frequently reported cause of surgery after total hip artroplasty. Revision total hip artroplasty can be difficult, especially when poor bone stock is encountered. The aim of this study was to examine the results of late periprosthetic fractures complicated with primary implant loosening performed with distal fixation modular revision stem. Methods From November 1999 to May 2006, 16 late periprosthetic fractures were treated with distal-fixation, modular, straight stem. There were 13 females (82%) and 3 males (18%) whose mean age at surgery was 76.7 years (range, 48 to 95 years). Femoral revision surgery was performed with the Revitan (2 cases) and ZMR (14 cases) to get a stable distal primary fixation. X-rays were assessed accordingly to the Vancouver classification: there were 3 type B2 and 13 type B3 fractures. Mean post-operative follow-up was 52 months (range, 10 to 88 months). At the time of the last follow-up visit 4 patients already passed away, all of them for causes unrelated to the procedure. The clinical outcome was monitored with the Harris Hip Score, subjective VAS, pain and satisfaction evaluation. Standard AP and lateral x-rays of the hip were obtained at each follow-up visit. Leg-length discrepancy was also investigated as a factor possibly affecting outcome. Complications included one septic loosening that was treated with a two-stage revision. Results All the patients but one were finally able to walk and had minimal to no pain at all. A satisfactory functional outcome was achieved with an average 76 (range, 25 to 100) Harris Hip Scores points. The subjective pain and satisfaction scores were respectively 2.4 and 7.8 points. As far as radiograms are concerned, all the sixteen femur did show a good healing of the fracture, with no secondary stem subsidence. Discussion Generally, considering the severity of an event such as a periprosthetic late fracture in an elderly patient, results were satisfactory. The average Harris Hip Score and subjective satisfaction would have been even higher if one patient wouldn\u2019t have been so much disappointed because of her severe leg-length discrepancy, dependent on the acetabular side. From a surgical point of view, the employed devices proved to be handy in bridging the fracture with distal fixation while adequately stabilizing it. Conclusions According to the reported results, straight modular-revison stems provide an adequate treatment option of Vancouver type B3 and in selected cases of B2 type periprosthetic femoral fracture

The Cosmic Web from Perturbation Theory

Context: Analyzing the large-scale structure (LSS) with galaxy surveys demands accurate structure formation models. Such models should ideally be fast and have a clear theoretical framework to rapidly scan a variety of cosmological parameter spaces without requiring large training data sets. Aims: This study aims to extend Lagrangian perturbation theory (LPT), including viscosity and vorticity, to reproduce the cosmic evolution from dark matter N-body calculations at the field level. Methods: We extend LPT to an Eulerian framework, dubbed eALPT. An ultraviolet regularisation through the spherical collapse model provided by Augmented LPT, turns out to be crucial at low redshifts. This enables modelling the stress tensor, with this introducing vorticity. The model has two free parameters apart from the choice of cosmology, redshift snapshots, cosmic volume, and the number of particles-cells. Results: We find that the cross-correlation of the dark matter distribution as compared to N-body solvers increases at $k = 1\,h$ Mpc$^{-1}$ and $z = 0$ from $\sim$55\% with the Zel'dovich approximation ($\sim$70\% with ALPT), to $\sim$95\% with three timesteps eALPT, and power spectra within percentage accuracy up to $k \simeq 0.3\,h$ Mpc$^{-1}$.Comment: 6 pages, 3 figure

The functional role of the parieto-frontal mirror circuit: interpretations and misinterpretations

The parieto-frontal cortical circuit that is active during action observation is the circuit with mirror properties that has been most extensively studied. Yet, there remains controversy on its role in social cognition and its contribution to understanding the actions and intentions of other individuals. Recent studies in monkeys and humans have shed light on what the parieto-frontal cortical circuit encodes and its possible functional relevance for cognition. We conclude that, although there are several mechanisms through which one can understand the behaviour of other individuals, the parieto-frontal mechanism is the only one that allows an individual to understand the action of others \u2018from the inside\u2019 and gives the observer a first-person grasp of the motor goals and intentions of other individuals

Immobilization of lysozyme on polyvinylalcohol films for active packaging applications.

A new technique for the immobilization of lysozyme onto the surface of polyvinylalcohol films is presented. The active compound was sprayed along with a suitable bonding agent onto the surface of the cross-linked polymeric matrix. Active compound release tests determined the amount of lysozyme immobilized on the film surface. With the use of Micrococcus lysodeikticus, the antimicrobial activity of the films was determined and the results correlated with the amount of immobilized lysozyme. This new technique was effective for immobilizing the enzyme, and the developed films were active against the test microorganism. Results were compared with those obtained with a different immobilizing technique, in which the active compound was bound into the bulk of the polymeric film. As expected, the surface-immobilized lysozyme films have a higher antimicrobial activity than bulk-bound films

Reopening schools during the COVID-19 pandemic: Overview and rapid systematic review of guidelines and recommendations on preventive measures and the management of cases

Given the limited evidence of school closure effectiveness in containing the pandemic and the consequences for young people, reopening schools with appropriate measures is essential. This overview aimed to describe the main measures planned for the 2020–2021 academic year within the WHO European Region. A rapid systematic review of scientific databases was also performed. The websites of the government, Ministry of Health, and Ministry of Education of European Region countries were searched through 1 October for official documents about the prevention and management of suspected cases/confirmed cases in primary and secondary schools. To find further suggestions, a rapid systematic review was conducted through 20 October searching Pubmed, Scopus, and Embase. There were 23 official documents. France, Luxembourg, Malta, Ireland, Italy, Portugal, the UK, Spain, and San Marino were considered. Performing the rapid review, 855 records were identified and 7 papers were finally selected. The recommendations mostly agreed. However, there was no consensus on the criteria for the return to school of students that tested positive, and the flexibility between attendance at school and remote education for high-risk children often varied. School closure was commonly considered as the very last resort for COVID-19 control. Studies are required to evaluate the impact of different recommendations during this autumn term