Time-resolved charge detection in graphene quantum dots

We present real-time detection measurements of electron tunneling in a graphene quantum dot. By counting single electron charging events on the dot, the tunneling process in a graphene constriction and the role of localized states are studied in detail. In the regime of low charge detector bias we see only a single time-dependent process in the tunneling rate which can be modeled using a Fermi-broadened energy distribution of the carriers in the lead. We find a non-monotonic gate dependence of the tunneling coupling attributed to the formation of localized states in the constriction. Increasing the detector bias above 2 mV results in an increase of the dot-lead transition rate related to back-action of the charge detector current on the dot.Comment: 8 pages, 6 figure

Feasibility of manufacturing a patient-specific spinal implant

Spinal fusion is performed for degenerative spinal condition when conservative measures fail. Implant size and shape are not standardised between manufacturers, and best match often means compromises. Bioprinting offers a unique opportunity to create a tailor-made solution. PURPOSE: The goal of this study was to design and manufacture a 3D-printed lumbar cage for lumbar interbody fusion

Computational models for characterisation and design of patient-specific spinal implant

BACKGROUND CONTEXT: Spinal fusion is designed to reduce movements between vertebrae and therefore pain. The most used devices for this procedure are mainly made of titanium or polyether ether ketone (PEEK). However, the mismatch between devices, with standard shapes and materials, and the surrounding bones can lead to suboptimal outcomes. Computational models, namely, Finite Element Analyses (FEA), can be employed to optimise existing device and design more effective solutions. PURPOSE: The goal of this study was to compare the performance of different materials and material densities for spinal cages, and to design a novel geometry which can ideally match the anatomical characteristics of a patient. STUDY DESIGN/SETTING: Computational. PATIENT SAMPLE: Nil. OUTCOME MEASURES: Nil. METHODS: FEA were set up to simulate compression (400 N) and bending (7.5 Nm) on a generic cage design. Three materials were modelled: titanium, PEEK and polycarbonate. Polycarbonate was included as widely available within additive manufacturing techniques. For each of the cages, four designs were modelled with varying material filling density. Furthermore, a new cage was modelled to match the pre-operative computed tomography (CT) of a patient exactly. The patient-specific cage was also tested by means of FEA. RESULTS: Stress distribution was compared between all the three materials tested. Consistently, stresses increased with reducing material density. Stress peak values were lower than the respective risk of failure in all the simulated cases, confirming the feasibility of polycarbonate implants. The patient-specific design showed even stress distribution consistently within anatomical constraints. CONCLUSIONS: Computational analyses suggested the feasibility of a lighter, cheaper and patient-specific cage for spinal fusion

Immediate Nonocclusal Versus Early Loading of Dental Implants in Partially Edentulous Patients – —15-year Follow-up of a Multicentre Randomised Controlled Trial

PURPOSE. To compare peri-implant bone and soft-tissue levels at immediately non-oc-clusally loaded versus non-submerged early-loaded implants in partially edentulous patients 15 years after loading. MATERIALS AND METHODS. Fifty-two patients from five Italian private practices were randomised, 25 to immediate loading and 27 to early loading. To be immediately loaded, single full Osseotite implants had to be inserted with a torque of at least 30 Ncm, and splinted implants with a torque of at least 20 Ncm. Immediately loaded implants were provided with non-occluding temporary restorations within 48 hours, which were brought into full occlusion after 2 months. In the early loading group, implants were loaded after 2 months. Definitive restorations were provided 8 months after implant placement in both groups. Outcome measures were prosthesis failures, implant failures and complica-tions, recorded by non-blinded assessors, and peri-implant bone and soft-tissue levels, as evaluated by blinded assessors. RESULTS. Fifty implants were loaded immediately and 54 early. Twelve patients with 24 implants dropped out from the immediate group versus 11 patients with 22 implants from the early loaded group, but all remaining patients were followed up for at least 15 years after loading. One single implant with its provisional crowns and one definitive prothesis failed in the immediate loading group. Seven patients with immediately loaded and two with early loaded implants reported complications. There were no statistically significant differences between groups in terms of implant failures (Fisher’s exact test P = 0.481; diff. =-0.04, 95% CI:-0.16 to 0.08), prosthesis failures (Fisher’s exact test P = 0.226; diff. =-0.08, 95% CI:-0.21 to 0.06), or complications (Fisher’s exact test P = 0.066; diff. =-0.22, 95% CI:-0.41 to 0.01). There were also no statistically significant differences in peri-implant bone (diff. = 0.28 mm, 95%CI:-0.35 to 0.91; P = 0.368) or soft-tissue level changes (diff. = 0.34 mm, 95%CI:-0.32 to 1.00; P = 0.292) between the two groups. Specifically, after 15 years immediately loaded patients had lost an average of 1.75 mm, and early loaded patients an average of 1.44 mm of peri-implant marginal bone. CONCLUSIONS. The long-term prognosis of prostheses supported by both immediately and early-loaded implants seems favourable

Perturbative versus Non-perturbative QFT -- Lessons from the O(3) NLS Model

The two-point functions of the energy-momentum tensor and the Noether current are used to probe the O(3) nonlinear sigma model in an energy range below 10^4 in units of the mass gap $m$. We argue that the form factor approach, with the form factor series trunctated at the 6-particle level, provides an almost exact solution of the model in this energy range. The onset of the (2-loop) perturbative regime is found to occur only at energies around $100m$.Comment: 13 pages LaTex, 4 PostScript figures; version published in Physics Letters

Effects of nicotine on microvascular responsiveness after nicotine satiety versus overnight nicotine abstinence

[no abstract available

Patient-specific blood flow simulations in the pulmonary bifurcation of patients with tetralogy of fallot

Dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common chronic complications in adult patients with tetralogy of Fallot; the most common cyanotic congenital heart disease with an estimate prevalence 1 in 3000 live births. Clinical consequences include, but are not limited to, abnormal lung development and elevated pulmonary vascular resistance. It is, therefore, crucial to better understand and characterise the haemodynamic environment in the pulmonary bifurcation to better diagnose and treat these patients. In this study, we have focused on investigating the blood flow dynamics in patient-specific geometries of the pulmonary bifurcation by means of computational models

Design and fabrication of 3D-printed anatomically shaped lumbar cage for intervertebra disc (IVD) degeneration treatment

Spinal fusion is the gold standard surgical procedure for degenerative spinal conditions when conservative therapies have been unsuccessful in rehabilitation of patients. Novel strategies are required to improve biocompatibility and osseointegration of traditionally used materials for lumbar cages. Furthermore, new design and technologies are needed to bridge the gap due to the shortage of optimal implant sizes to fill the intervertebral disc defect. Within this context, additive manufacturing technology presents an excellent opportunity to fabricate ergonomic shape medical implants. The goal of this study is to design and manufacture a 3D-printed lumbar cage for lumbar interbody fusion. Optimisations of the proposed implant design and its printing parameters were achieved via in silico analysis. The final construct was characterised via scanning electron microscopy, contact angle, x-ray micro computed tomography (μCT), atomic force microscopy, and compressive test. Preliminary in vitro cell culture tests such as morphological assessment and metabolic activities were performed to access biocompatibility of 3D-printed constructs. Results of in silico analysis provided a useful platform to test preliminary cage design and to find an optimal value of filling density for 3D printing process. Surface characterisation confirmed a uniform coating of nHAp with nanoscale topography. Mechanical evaluation showed mechanical properties of final cage design similar to that of trabecular bone. Preliminary cell culture results showed promising results in terms of cell growth and activity confirming biocompatibility of constructs. Thus for the first time, design optimisation based on computational and experimental analysis combined with the 3D-printing technique for intervertebral fusion cage has been reported in a single study. 3D-printing is a promising technique for medical applications and this study paves the way for future development of customised implants in spinal surgical applications

Varying the Unruh Temperature in Integrable Quantum Field Theories

A computational scheme is developed to determine the response of a quantum field theory (QFT) with a factorized scattering operator under a variation of the Unruh temperature. To this end a new family of integrable systems is introduced, obtained by deforming such QFTs in a way that preserves the bootstrap S-matrix. The deformation parameter \beta plays the role of an inverse temperature for the thermal equilibrium states associated with the Rindler wedge, \beta = 2\pi being the QFT value. The form factor approach provides an explicit computational scheme for the \beta \neq 2\pi systems, enforcing in particular a modification of the underlying kinematical arena. As examples deformed counterparts of the Ising model and the Sinh-Gordon model are considered.Comment: 34 pages, Latex, 3 Figures, minor change

Peripheral and central effects of smokeless tobacco on exercise endurance in men

Introduction A proliferation of nicotine use in the sport environment has been observed in recent years mainly as smokeless tobacco (Zandonai et al., 2013). Nicotine has been listed in World Anti-doping Agency’s Monitoring Program from 2012 to 2015 in order to detect potential patterns of abuse. The aim of this study was to investigate the effects of Snus (SS), an oral smokeless tobacco, on the perception of fatigue during aerobic exercise to TTE. Methods The study was a double-blind placebo controlled (SP) crossover design. Fourteen healthy male non-smokers were recruited. Subjects were studied during three sessions on cycle-ergometer: experimental session 1 (Exp1) consisted in an incremental exercise test to determine maximal aerobic power (Wmax); Exp2 and Exp3 consisted in exercise at 65% Wmax until exhaustion in SS or SP conditions. During the Exp2 and Exp3, muscle and cerebral oxygenation by means of NIRS (nearinfrared spectroscopy) and global rating of perceived exertion (RPE) were recorded. Before and after all experiments, the Profile of Mood of State questionnaire (POMS) was administered to subjects. Subjects were then tested by means of Transcranial Magnetic Stimulation (TMS) to assess changes in cortico-motor excitability due to the prolonged exercise. Results Time to exhaustion (TTE) was not significant difference (64.4 ± 41.5 min SS; 51.6 ± 17.2 min SP) (19.2%) in paired Student’s t-test. RPE in the first 30 minutes during both of the sessions showed a significant difference after 10 minutes from start exercise. POMS questionnaire values did not show any significant differences under both conditions (SS, SP). We found significant differences in the cerebral and muscular tissues oxygenation levels in the first 30 minutes of the exercise during SS and SP tests. In particular, at cerebral level, tissue oxygenation index was significantly larger in SS than in SP from the 10th to 30th min of exercise. Conclusion The study showed that the SS effect, compared to placebo condition, could not be an improvement of fatigue during an endurance exercise until exhaustion despite of an increase in tissue muscular and cerebral oxygenation. These data supported the hypothesis of a major activity induced by nicotine as a central stimulator (Mundel and Jones, 2006). References Mundel T, Jones DA. (2006). Effect of transdermal nicotine administration on exercise endurance in men. Exp Physiol, 91, 705- 713 Zandonai T, Baraldo M, Franceschi L, Zappamiglio T, Chiamulera C. (2013). Effects of smokeless tobacco (snus) administration on exercise endurance in men. SRNT Annual Meeting Boston MA (USA) p 16