Holographic fermions in external magnetic fields

We study the Fermi level structure of 2+1-dimensional strongly interacting electron systems in external magnetic field using the AdS/CFT correspondence. The gravity dual of a finite density fermion system is a Dirac field in the background of the dyonic AdS-Reissner-Nordstrom black hole. In the probe limit the magnetic system can be reduced to the non-magnetic one, with Landau-quantized momenta and rescaled thermodynamical variables. We find that at strong enough magnetic fields, the Fermi surface vanishes and the quasiparticle is lost either through a crossover to conformal regime or through a phase transition to an unstable Fermi surface. In the latter case, the vanishing Fermi velocity at the critical magnetic field triggers the non-Fermi liquid regime with unstable quasiparticles and a change in transport properties of the system. We associate it with a metal-"strange metal" phase transition. Next we compute the DC Hall and longitudinal conductivities using the gravity-dressed fermion propagators. For dual fermions with a large charge, many different Fermi surfaces contribute and the Hall conductivity is quantized as expected for integer Quantum Hall Effect (QHE). At strong magnetic fields, as additional Fermi surfaces open up, new plateaus typical for the fractional QHE appear. The somewhat irregular pattern in the length of fractional QHE plateaus resemble the outcomes of experiments on thin graphite in a strong magnetic field. Finally, motivated by the absence of the sign problem in holography, we suggest a lattice approach to the AdS calculations of finite density systems.Comment: 34 pages, 14 figure

Transport efficiency in topologically disordered networks with environmentally induced diffusion

We study transport in topologically disordered networks that are subjected to an environment that induces classical diffusion. The dynamics is phenomenologically described within the framework of the recently introduced quantum stochastic walk, allowing to study the crossover between coherent transport and purely classical diffusion. We find that the coupling to the environment removes all effects of localization and quickly leads to classical transport. Furthermore, we find that on the level of the transport efficiency, the system can be well described by reducing it to a two-node network (a dimer).Comment: 10 pages, 7 figure

Virtual reality training for endoscopic surgery: voluntary or obligatory?

INTRODUCTION: Virtual reality (VR) simulators have been developed to train basic endoscopic surgical skills outside of the operating room. An important issue is how to create optimal conditions for integration of these types of simulators into the surgical training curriculum. The willingness of surgical residents to train these skills on a voluntary basis was surveyed. METHODS: Twenty-one surgical residents were given unrestricted access to a VR simulator for a period of four months. After this period, a competitive element was introduced to enhance individual training time spent on the simulator. The overall end-scores for individual residents were announced periodically to the full surgical department, and the winner was awarded a prize. RESULTS: In the first four months of study, only two of the 21 residents (10%) trained on the simulator, for a total time span of 163 minutes. After introducing the competitive element the number of trainees increased to seven residents (33%). The amount of training time spent on the simulator increased to 738 minutes. CONCLUSIONS: Free unlimited access to a VR simulator for training basic endoscopic skills, without any form of obligation or assessment, did not motivate surgical residents to use the simulator. Introducing a competitive element for enhancing training time had only a marginal effect. The acquisition of expensive devices to train basic psychomotor skills for endoscopic surgery is probably only effective when it is an integrated and mandatory part of the surgical curriculu

Perceptions of surgical specialists in general surgery, orthopaedic surgery, urology and gynaecology on teaching endoscopic surgery in The Netherlands

BACKGROUND: Specific training in endoscopic skills and procedures has become a necessity for profession with embedded endoscopic techniques in their surgical palette. Previous research indicates endoscopic skills training to be inadequate, both from subjective (resident interviews) and objective (skills measurement) viewpoint. Surprisingly, possible shortcomings in endoscopic resident education have never been measured from the perspective of those individuals responsible for resident training, e.g. the program directors. Therefore, a nation-wide survey was conducted to inventory current endoscopic training initiatives and its possible shortcomings among all program directors of the surgical specialties in the Netherlands. METHODS: Program directors for general surgery, orthopaedic surgery, gynaecology and urology were surveyed using a validated 25-item questionnaire. RESULTS: A total of 113 program directors responded (79%). The respective response percentages were 73.6% for general surgeons, 75% for orthopaedic surgeon, 90.9% for urologists and 68.2% for gynaecologists. According to the findings, 35% of general surgeons were concerned about whether residents are properly skilled endoscopically upon completion of training. Among the respondents, 34.6% were unaware of endoscopic training initiatives. The general and orthopaedic surgeons who were aware of these initiatives estimated the number of training hours to be satisfactory, whereas the urologists and gynaecologists estimated training time to be unsatisfactory. Type and duration of endoscopic skill training appears to be heterogeneous, both within and between the specialties. Program directors all perceive virtual reality simulation to be a highly effective training method, and a multimodality training approach to be key. Respondents agree that endoscopic skills education should ideally be coordinated according to national consensus and guidelines. CONCLUSIONS: A delicate balance exists between training hours and clinical working hours during residency. Primarily, a re-allocation of available training hours, aimed at core-endoscopic basic and advanced procedures, tailored to the needs of the resident and his or her phase of training is in place. The professions need to define which basic and advanced endoscopic procedures are to be trained, by whom, and by what outcome standards. According to the majority of program directors, virtual reality (VR) training needs to be integrated in procedural endoscopic training course

Augmented versus Virtual Reality Laparoscopic Simulation: What Is the Difference?: A Comparison of the ProMIS Augmented Reality Laparoscopic Simulator versus LapSim Virtual Reality Laparoscopic Simulator

BACKGROUND: Virtual reality (VR) is an emerging new modality for laparoscopic skills training; however, most simulators lack realistic haptic feedback. Augmented reality (AR) is a new laparoscopic simulation system offering a combination of physical objects and VR simulation. Laparoscopic instruments are used within an hybrid mannequin on tissue or objects while using video tracking. This study was designed to assess the difference in realism, haptic feedback, and didactic value between AR and VR laparoscopic simulation. METHODS: The ProMIS AR and LapSim VR simulators were used in this study. The participants performed a basic skills task and a suturing task on both simulators, after which they filled out a questionnaire about their demographics and their opinion of both simulators scored on a 5-point Likert scale. The participants were allotted to 3 groups depending on their experience: experts, intermediates and novices. Significant differences were calculated with the paired t-test. RESULTS: There was general consensus in all groups that the ProMIS AR laparoscopic simulator is more realistic than the LapSim VR laparoscopic simulator in both the basic skills task (mean 4.22 resp. 2.18, P <0.000) as well as the suturing task (mean 4.15 resp. 1.85, P <0.000). The ProMIS is regarded as having better haptic feedback (mean 3.92 resp. 1.92, P <0.000) and as being more useful for training surgical residents (mean 4.51 resp. 2.94, P <0.000). CONCLUSIONS: In comparison with the VR simulator, the AR laparoscopic simulator was regarded by all participants as a better simulator for laparoscopic skills training on all tested feature

The EAES intellectual property awareness survey

Introduction: The protection of intellectual property (IP) is one of the fundamental elements in the process of medical device development. The significance of IP, however, is not well understood among clinicians and researchers. The purpose of this study was to evaluate the current status of IP awareness and IP-related behaviors among EAES members. / Methods: A web-based survey was conducted via questionnaires sent to EAES members. Data collected included participant demographics, level of understanding the need, new ideas and solutions, basic IP knowledge, e.g., employees' inventions and public disclosure, behaviors before and after idea disclosures. / Results: One hundred and seventy-nine completed forms were obtained through an email campaign conducted twice in 2019 (response rate = 4.8%). There was a dominancy in male, formally-trained gastrointestinal surgeons, working at teaching hospitals in European countries. Of the respondents, 71% demonstrated a high level of understanding the needs (frustration with current medical devices), with 66% developing specific solutions by themselves. Active discussion with others was done by 53%. Twenty-one percent of respondents presented their ideas at medical congresses, and 12% published in scientific journals. Only 20% took specific precautions or appropriate actions to protect their IPs before these disclosures. / Conclusions: The current level of awareness of IP and IP-related issues is relatively low among EAES members. A structured IP training program to gain basic IP knowledge and skill should be considered a necessity for clinicians. These skills would serve to prevent the loss of legitimate IP rights and avoid failure in the clinical implementation of innovative devices for the benefit of patients

Will the Playstation generation become better endoscopic surgeons?

A frequently heard comment is that the current "Playstation generation" will have superior baseline psychomotor skills. However, research has provided inconsistent results on this matter. The purpose of this study was to investigate whether the "Playstation generation" shows superior baseline psychomotor skills for endoscopic surgery on a virtual reality simulator. The 46 study participants were interns (mean age 24 years) of the department of surgery and schoolchildren (mean age 12.5 years) of the first year of a secondary school. Participants were divided into four groups: 10 interns with videogame experience and 10 without, 13 schoolchildren with videogame experience and 13 without. They performed four tasks twice on a virtual reality simulator for basic endoscopic skills. The one-way analysis of variance (ANOVA) with post hoc test Tukey-Bonferroni and the independent Student's t test were used to determine differences in mean scores. Interns with videogame experience scored significantly higher on total score (93 vs. 74.5; p=0.014) compared with interns without this experience. There was a nonsignificant difference in mean total scores between the group of schoolchildren with and those without videogame experience (61.69 vs. 55.46; p=0.411). The same accounts for interns with regard to mean scores on efficiency (50.7 vs. 38.9; p=0.011) and speed (18.8 vs. 14.3; p=0.023). In the group of schoolchildren, there was no statistical difference for efficiency (32.69 vs. 27.31; p=0.218) or speed (13.92 vs. 13.15; p=0.54). The scores concerning precision parameters did not differ for interns (23.5 vs. 21.3; p=0.79) or for schoolchildren (mean 15.08 vs. 15; p=0.979). Our study results did not predict an advantage of videogame experience in children with regard to superior psychomotor skills for endoscopic surgery. However, at adult age, a difference in favor of gaming is present. The next generation of surgeons might benefit from videogame experience during their childhoo

Online Guide for Electronic Health Evaluation Approaches: Systematic Scoping Review and Concept Mapping Study

BACKGROUND: Despite the increase in use and high expectations of digital health solutions, scientific evidence about the effectiveness of electronic health (eHealth) and other aspects such as usability and accuracy is lagging behind. eHealth solutions are complex interventions, which require a wide array of evaluation approaches that are capable of answering the many different questions that arise during the consecutive study phases of eHealth development and implementation. However, evaluators seem to struggle in choosing suitable evaluation approaches in relation to a specific study phase. OBJECTIVE: The objective of this project was to provide a structured overview of the existing eHealth evaluation approaches, with the aim of assisting eHealth evaluators in selecting a suitable approach for evaluating their eHealth solution at a specific evaluation study phase. METHODS: Three consecutive steps were followed. Step 1 was a systematic scoping review, summarizing existing eHealth evaluation approaches. Step 2 was a concept mapping study asking eHealth researchers about approaches for evaluating eHealth. In step 3, the results of step 1 and 2 were used to develop an "eHealth evaluation cycle" and subsequently compose the online "eHealth methodology guide." RESULTS: The scoping review yielded 57 articles describing 50 unique evaluation approaches. The concept mapping study questioned 43 eHealth researchers, resulting in 48 unique approaches. After removing duplicates, 75 unique evaluation approaches remained. Thereafter, an "eHealth evaluation cycle" was developed, consisting of six evaluation study phases: conceptual and planning, design, development and usability, pilot (feasibility), effectiveness (impact), uptake (implementation), and all phases. Finally, the "eHealth methodology guide" was composed by assigning the 75 evaluation approaches to the specific study phases of the "eHealth evaluation cycle." CONCLUSIONS: Seventy-five unique evaluation approaches were found in the literature and suggested by eHealth researchers, which served as content for the online "eHealth methodology guide." By assisting evaluators in selecting a suitable evaluation approach in relation to a specific study phase of the "eHealth evaluation cycle," the guide aims to enhance the quality, safety, and successful long-term implementation of novel eHealth solutions