Compound surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a periodically multilayered isotropic dielectric material

Multiple p- and s-polarized compound surface plasmon-polariton (SPP) waves at a fixed frequency can be guided by a structure consisting of a metal layer sandwiched between a homogeneous isotropic dielectric (HID) material and a periodic multilayered isotropic dielectric (PMLID) material. For any thickness of the metal layer, at least one compound SPP wave must exist. It possesses the p-polarization state, is strongly bound to the metal/HID interface when the metal thickness is large but to both metal/dielectric interfaces when the metal thickness is small. When the metal layer vanishes, this compound SPP wave transmutes into a Tamm wave. Additional compound SPP waves exist, depending on the thickness of the metal layer, the relative permittivity of the HID material, and the period and the composition of the PMLID material. Some of these are p polarized, the others being s polarized. All of them differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. The multiplicity and the dependence of the number of compound SPP waves on the relative permittivity of the HID material when the metal layer is thin could be useful for optical sensing applications.Comment: 17 page

Compound surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a structurally chiral material

Multiple compound surface plasmon-polariton (SPP) waves can be guided by a structure consisting of a sufficiently thick layer of metal sandwiched between a homogeneous isotropic dielectric (HID) material and a dielectric structurally chiral material (SCM). The compound SPP waves are strongly bound to both metal/dielectric interfaces when the thickness of the metal layer is comparable to the skin depth but just to one of the two interfaces when the thickness is much larger. The compound SPP waves differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. Some compound SPP waves are not greatly affected by the choice of the direction of propagation in the transverse plane but others are, depending on metal thickness. For fixed metal thickness, the number of compound SPP waves depends on the relative permittivity of the HID material, which can be useful for sensing applications

Novel Therapies in HBV Infection

Current treatments for chronic hepatitis B are able to provide a sustained suppression of the viral replication (i.e., persistent undetectability of HBV DNA). This leads to improvement of liver fibrosis and reduction of clinical complications. However, hepatitis B surface antigen (HBsAg) persists in most patients, probably justifying a still increased risk of hepatocellular carcinoma. Indeed, obtaining a complete and sterilizing cure with elimination of the covalently closed circular DNA (cccDNA) or silencing its activity is still a holy grail. New molecules are under evaluation to suppress viral replication acting on multiple phases of the HBV cycle or improve specific immune response against HBV. Molecules acting on HBV cycle have already showed encouraging results, such as entry inhibitors, small interfering RNAs (siRNAs), capsid assembly modulators (CAMs), nucleic acid polymers (NAPs). Also, promising results have been observed with immune-modulators, therapeutic vaccines, and other immune-based approaches. Among these, toll-like (TLR) or anti-programmed receptor agonists antibody 1 of the cell death protein (PD1) (e.g., nivolumab) are most promising. This paper describes newer drugs appearing on the horizon, including antiviral drugs targeting different steps of the HBV life cycle and therapeutic approaches based on immune-modulation

Use of Knee Fractures Physical Replicas for Surgical Training and Rehearsal: Proof of Concept Study

In the last years also in orthopedic surgery, there was an increasing interest in the development of surgical simulators using methods of additive manufacturing combined or not with augmented reality systems (hybrid simulators). Aim of this work was to evaluate the use of a new patient’s specific tibial plateau fractures simulator for surgical training of young resident surgeons in fracture fixation with an external fixator. The simulator is a realistic knee phantom including a patient-specific replica of a fractured tibia and fibula, obtained by CT segmentation and rapid prototyping techniques. Each training session started with the presentation, and planning, of the surgical case that it was followed by the external fixation session on the simulator. At the end of each session, all participants were asked to fill out a questionnaire, concerning the phantom realism and appropriateness as a teaching modality. The results of the Likert Questionnaire indicating that there is an overall significant agreement with the phantom realism and its appropriateness as a teaching modality. The solid model of the patient’s anatomy can faithfully reproduce the surgical complexity of the patient and it allows to generate surgical simulators with an increasing difficulty to perform structured training paths: from the "simple" case to the "complex" case. The use of simulators based on 3D models has proved to be a very useful tool both for didactic and surgical training purposes, allowing surgeons to perform a real procedure simulation outside the surgical room

Off-Label Use of Dalbavancin for Sequential Treatment of Spondylodiscitis by Methicillin-Resistant Staphylococcus aureus: A Retrospective Single-Centre Experience

Background: Our aim was to describe the clinical outcome and safety of the sequential treatment with off-label dalbavancin in patients with spondylodiscitis that is caused by methicillin-resistant Staphylococcus aureus (MRSA). Methods: We retrospectively included all patients >18 years of age with spondylodiscitis that is caused by MRSA that was treated with dalbavancin from January 2018-January 2021, recording the instances of clinical cure/failure, adverse events, and the need to be re-hospitalized after the initiation of dalbavancin. In 2/15 patients, we performed therapeutic drug monitoring (TDM) for dalbavancin. Results: We included 15 patients, 53.3% of them were females, with a median age of 67.9 years (57.4-78.5); 100% patients reported back pain, while a fever was present only in 2/15 cases. The spondylodiscitis was localized in 86.6% cases at the lumbar level. A median of a 2-week in-hospital intravenous vancomycin was followed by dalbavancin with a median duration of 12 weeks (12-16). All patients reported a clinical cure, except for a woman who is still on a suppressive treatment. No patient needed to be re-hospitalized, access to emergency department, or experienced adverse events. The TDM for dalbavancin showed that more than 90% of the determinations were above the pharmacodynamic target against staphylococci. Conclusions: The results from our unique, even if it was small, cohort demonstrated that dalbavancin can be a safe/effective option as a sequential treatment in patients with serious infections requiring prolonged antibiotic therapy, such as spondylodiscitis

Patients Specific Spine Simulators for Surgical Training and Rehearsal in Pedicle Screws Placement: A New Way for Surgical Education

In pedicle screws placement using a free-hand technique or a fluoroscopic guided technique the main difficulties are facing to the bone morphology (i.e in deformity cases) and it could be easily reproduced in a patient’s specific spine simulator (we can choose the case). The aim of this work is to evaluate the use of 3D printed patient- specific models (3D printing) not only as a surgical planning tool but also as a surgical training tool in spine surgery and in particular in pedicle screws placement. The manufacturing of patient-specific physical replica involves the elaboration of CT dataset and rapid prototyping techniques. . Five resident surgeons were involved in different training sessions on simulators. To evaluate the exact screws position we performed a CT evaluation of each instrumented simulators. Statistical analysis was conducted using SPSS software. A total of 120 pedicle screws were positioned, 90 screws were well-positioned and 30 screws were bad-positioned. There were a significant difference (p = 0.000008) between the bad-positioning screw rate of the “senior” resident (13/72) and those of “young” participants (17/48). Timeline analysis of pedicle instrumentation training showed the presence of a learning effect, with a lower error rate in the latest session (p=000001). We believe that the use of patient- specific surgical simulators, especially for those surgical tasks in which the complexity is mainly linked to the spine morphology (i.e. deformity), may represent a valid alternative to the use of cadavers that generally present a standard or otherwise poorly predictable anatomy

Physical exercise and Sport activities in patients with and without coronary heart disease

Background: The quantity and intensity of physical activity required for the primary prevention of coronary heart disease remain unclear. Therefore, we examined the association between physical activity and coronary risk. Methods: We studied 100 patients with chest pain, 78 men and 22 women, not older than 65 years, admitted to a coronary care unit. Patients were subdivided in 3 groups: the first group included patients with acute myocardial infarction, the second group included patients with chronic heart disease, the third included patients with non-ischemic chest-pain. A questionnaire on daily physical activity was filled by each patient. Results: A significantly higher percentage of patients with myocardial infarction and coronary heart disease had a sedentary life style compared to patients of the third group. Compared with subjects without heart disease, a significantly higher percentage of patients of the first and second group covered a daily average distance shorter than 500 meters, while a significantly inferior percentage covered a distance longer than 1 Km every day. A significantly lower percentage of patients with coronary heart disease practised sport compared with the third group. At the time of hospitalization a very small percentage of coronary heart disease patients still practised sport. Conclusions: The association between physical activity and reduced coronary risk is clear; in order to obtain benefits it is sufficient just walking every day. Regarding physical activity, continuity is important: patients, who practised sport only in juvenile age, breaking off when older, may lose the obtained advantages

Signatures of thermal hysteresis in Tamm-wave propagation

We numerically solved the boundary-value problem for Tamm waves (which may also be classified as Uller-Zenneck waves here) guided by the planar interface of a homogeneous isotropic dissipative dielectric (HIDD) material and a periodically multilayered isotropic dielectric material. The HIDD material was chosen to be VO${}_2$ which, at optical wavelengths, has a temperature-dependent refractive index with a hysteresis feature, i.e., the temperature-dependence of its refractive index varies depending upon whether the temperature is increasing or decreasing. A numerical code was implemented to extract solutions of the dispersion equation at a fixed wavelength for both $p$- and $s$-polarization states over the temperature range [50,80] degrees. A multitude of Tamm waves of both linear polarization states were found, demonstrating a clear demarcation of the heating and cooling phases in terms of wavenumbers and propagation distances. Thereby, the signatures of thermal hysteresis in Tamm-wave propagation were revealed

Temperature-mediated transition from Dyakonov-Tamm surface waves to surface-plasmon-polariton waves

The effect of changing the temperature on the propagation of electromagnetic surface waves (ESWs), guided by the planar interface of a homogeneous isotropic temperature-sensitive material (namely, InSb) and a temperature-insensitive structurally chiral material (SCM) was numerically investigated in the terahertz frequency regime. As the temperature rises, InSb transforms from a dissipative dielectric material to a \blue{dissipative} plasmonic material. Correspondingly, the ESWs transmute from Dyakonov--Tamm surface waves into surface--plasmon--polariton waves. The effects of the temperature change are clearly observed in the phase speeds, propagation distances, angular existence domains, multiplicity, and spatial profiles of energy flow of the ESWs. Remarkably large propagation distances can be achieved; in such instances the energy of an ESW is confined almost entirely within the SCM. For certain propagation directions, simultaneous excitation of two ESWs with (i) the same phase speeds but different propagation distances or (ii) the same propagation distances but different phase speeds are also indicated by our results