We present a theoretical analysis of Dirac magneto-plasmons in topological insulator nanowires. We discuss a cylindrical geometry where Berry phase effects induce the opening of a gap at the neutrality point. By taking into account surface electron wave functions introduced in previous papers and within the random phase approximation, we provide an analytical form of the dynamic structure factor. Dispersions and spectral weights of Dirac plasmons are studied with varying the radius of the cylinder, the surface doping, and the strength of an external magnetic field. We show that, at zero surface doping, inter-band damped plasmon-like excitations form at the surface and survive at low electron surface dopings (∼ 10 10 cm −2 ). Then, we point out that the plasmon excitations are sensitive to the Berry phase gap closure when an external magnetic field close to half quantum flux is introduced. Indeed, a well-defined magneto-plasmon peak is observed at lower energies upon the application of the magnetic field. Finally, the increase of the surface doping induces a crossover from damped inter-band to sharp intra-band magneto-plasmons which, as expected for large radii and dopings (∼ 10 12 cm −2 ), approach the proper limit of a two-dimensional surface.
Background: Arthroscopic partial meniscectomy is a common procedure in orthopedic practice. Infections are uncommon complications of this procedure with an incidence rate of 0,01% -3,4%. Staphylococcus spp are the predominant causative agents in such cases. We present a case of knee septic arthritis caused by α-hemolytic Streptococcus.Case presentation: A 22-year-old woman diagnosed with obesity (body mass index [BMI] 35 kg/m 2 ) but with no other major comorbidities underwent an arthroscopic selective meniscectomy with administration of intravenous cefazolin for antibiotic prophylaxis. After an uneventful period of 2 months, the patient returned with pain, fever and a discharging sinus at the site of anterolateral arthroscopic portal. Blood tests and magnetic resonance imaging revealed osteomyelitis involving the tibial plate. Cultures of synovial fluid obtained from the knee and a pharyngeal swab yielded α-hemolytic Streptococcus. Five days later, the patient underwent arthroscopic debridement with partial synovectomy. Intraoperative specimens yielded α-hemolytic Streptococcus. The patient received intravenous piperacillin/tazobactam, followed by an associative regimen of amoxicillin and clindamycin with clinical, laboratory and instrumental evidence of symptom resolution. Conclusion: The incidence of knee septic arthritis after arthroscopic partial meniscectomy is 0.01-3.4%. This infection is usually caused by Staphylococcus spp. and in rare cases by commensal bacteria, such as α-hemolytic streptococci, secondary to transient bacteremia. Screening of the colonized area is important to prevent possible transient bacteremia. Diagnosis is based on isolation of the causative organisms from synovial fluid cultures, and treatment comprises arthroscopic debridement with individualized systemic antibiotic therapy based on the results of an antibiogram.
Category: Trauma Introduction/Purpose: There is increasing interest on how to best manage displaced intraarticular calcaneal fractures (DIACF). Intramedullary locking devices (ILDs) have recently been advocated since the technique adopts a minimally invasive approach which may minimise complications and therefore improve outcomes. We reviewed the literature of commercially available devices to identify their characteristics, efficacy and safety. Methods: Medline, Scopus and EMBASE databases were searched to identify studies reporting use of ILDs for treating DIACF. A PRISMA checklist was used to sort eligible studies. Technical notes and biomechanical studies were first reviewed. Cohort studies were then reviewed for demographics, surgical technique, postoperative protocol, clinical and radiographic scores, complications and reoperations. The modified Coleman Methodology Score (CMS) was used to assess the quality of studies. Results: Thirteen studies investigated two devices (Calcanail; C-Nail). Four technical notes described how to use these devices and three biomechanical studies proved they offered adequate primary stability, stiffness, interfragmentary motion and load to failure. Seven clinical studies (302 feet, 289 patients) demonstrated satisfactory clinical (AOFAS, VAS) and radiographic (Bohler’s angle, Gissane angle, Goldzak index, posterior facet step-off) outcome at 16-months average follow-up. Metalware irritation (up to 20%) and temporary nerve entrapment symptoms (up to 30%) were the most common complications; soft tissue issues were reported in 3-5% of cases. Conversion to subtalar fusion was necessary in 4-6% of cases. Four (57%) studies were authored by implant designers and in 5 (71%) relevant conflict of interest were disclosed. Mean CMS was 61 (moderate quality). Conclusion: Treating DIAFCs with ILDs leads to satisfactory clinical outcomes at short term follow-up, enabling restoration of calcaneal height and improved subtalar joint congruency. Metalware irritation and temporary nerve entrapment symptoms are common complications although wound complications including infection and wound breakdown are less frequent than after open lateral approaches. The quality of evidence provided so far is only moderate and biased by potential conflict of interest, raising concerns about the generalisability of results.
Tears of the gluteus medius can result in chronic hip pain over time. Pathological onsets involving the gluteus medius cause pain and weakness of abductor strength. Endoscopic repair is a suitable, effective and safe surgical alternative to traditional open techniques and give satisfactory results over time restoring the footprint of gluteus medius. The purpose of this systematic review is to analyse the effectiveness of endoscopic transtendinous technique for partial-thickness tears, analysing the subjective and functional outcome over the time. A search of literature (PubMed, Scopus, WebOfKnowledge) was performed. The PRISMA method was used to screen the articles. A total of 4 articles was screened and included for qualitative analysis. For data extraction patient characteristics, pre-clinical examination, imaging, timing from symptoms to surgery, technique performed, subjective scales, functional outcomes, post-operative clinical assessment were analysed. Subjective scores at mean follow-up of 18 months show a significative improvement in all the scales reported, in relief of pain (VAS score) and in terms of strength of abductor. Trans-tendinous technique represents the gold standard to treat endoscopically these injuries. Furthermore, other studies with larger number of patients and longer follow-up are required to validate the best surgical approach for these injuries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.