Lower and upper estimates on the excitation threshold for breathers in DNLS lattices

We propose analytical lower and upper estimates on the excitation threshold for breathers (in the form of spatially localized and time periodic solutions) in DNLS lattices with power nonlinearity. The estimation depending explicitly on the lattice parameters, is derived by a combination of a comparison argument on appropriate lower bounds depending on the frequency of each solution with a simple and justified heuristic argument. The numerical studies verify that the analytical estimates can be of particular usefulness, as a simple analytical detection of the activation energy for breathers in DNLS lattices.Comment: 10 pages, 3 figure

Stress and failure analysis of adhesively bonded single lap joints

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN028124 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Reconstruction nailing for ipsilateral femoral neck and shaft fractures

The surgical management of ipsilateral fractures of the femoral neck and shaft presents a difficult and challenging problem for the orthopaedic surgeon. The purpose of the present study was to report the mid-term results and complications in a series of patients who sustained ipsilateral femoral neck and shaft fractures and treated in our trauma department with a single reconstruction nail for both fractures. Eleven patients were included in the study with an average age of 46.4 years. The mean follow-up was 47 months (range, 15–75 months). There were no cases of a missed diagnosis at initial presentation. The mean time to union was 4.5 months for the neck fracture and 8.2 months for the shaft. There were no cases of avascular necrosis of the femoral head or non-union of the neck fracture. The mean Harris Hip Score was (85 ± 4.3). Complications included two cases of shaft fracture non-union and one case of peroneal nerve palsy. Heterotopic ossification at the tip of the greater trochanter was evident in two cases without causing any functional deficit. The current study suggests that reconstruction nailing produces satisfactory clinical and functional results in the mid-term. The complications involved only the femoral shaft fracture and were successfully treated with a single operative procedure

Kuznetsov-Ma breather-like solutions in the Salerno model

The Salerno model is a discrete variant of the celebrated nonlinear Schr\"odinger (NLS) equation interpolating between the discrete NLS (DNLS) equation and completely integrable Ablowitz-Ladik (AL) model by appropriately tuning the relevant homotopy parameter. Although the AL model possesses an explicit time-periodic solution known as the Kuznetsov-Ma (KM) breather, the existence of time-periodic solutions away from the integrable limit has not been studied as of yet. It is thus the purpose of this work to shed light on the existence and stability of time-periodic solutions of the Salerno model. In particular, we vary the homotopy parameter of the model by employing a pseudo-arclength continuation algorithm where time-periodic solutions are identified via fixed-point iterations. We show that the solutions transform into time-periodic patterns featuring small, yet non-decaying far-field oscillations. Remarkably, our numerical results support the existence of previously unknown time-periodic solutions {\it even} at the integrable case whose stability is explored by using Floquet theory. A continuation of these patterns towards the DNLS limit is also discussed.Comment: 9 pages, 4 figure

Propagation of periodic wave trains along the magnetic field in a collision-free plasma

In this work, a systematic study, examining the propagation of periodic and solitary wave along the magnetic field in a cold collision-free plasma, is presented. Employing the quasi-neutral approximation and the conservation of momentum flux and energy flux in the frame co-traveling with the wave, the exact analytical solution of the stationary solitary pulse is found analytically in terms of particle densities, parallel and transverse velocities, as well as transverse magnetic fields. Subsequently, this solution is generalized in the form of periodic waveforms represented by cnoidal-type waves. These considerations are fully analytical in the case where the total angular momentum flux $L$, due to the ion and electron motion together with the contribution due to the Maxwell stresses, vanishes. A graphical representation of all associated fields is also provided

Epidural bleeding after ACL reconstruction under regional anaesthesia: a case report

Introduction: Epidural bleeding as a complication of catheterization or epidural catheter removal is often associated with perioperative thromboprophylaxis especially in adult reconstructive surgery. Case presentation: We report on a case of a 19 years old male athlete that underwent anterior cruciate ligament reconstruction, receiving low molecular weight heparin for thromboprophylaxis and developed an epidural hematoma and subsequent cauda equina syndrome two days after removal of the epidural catheter. An urgent magnetic resonance imaging scan revealed an epidural hematoma from the level of L3 to L4. Emergent decompression and hematoma evacuation resulted in patient's significant neurological improvement immediately postoperatively. Conclusion: A high index of clinical suspicion and surgical intervention are necessary to prevent such potentially disabling complications especially after procedures on a day-case basis and early patient's discharge. © 2009 Roidis et al; licensee Cases Network Ltd

Practicalities of BVID detection on aerospace-grade CFRP materials with optical fibre sensors

Several reports have recently shown the capability of optical fibre sensors for the detection of barely visible impact damage (BVID) on CFRP laminates, based on changes in the optical signal before and after impact. Although this approach was shown to work well in lab conditions, little attention has been paid so far to its practicality when considering realistic ambient conditions or to the detection range. In this work we attempt to derive BVID detection thresholds for fibre Bragg grating-based sensors, by considering standardized temperature and vibration levels for aerospace applications. To the best of our knowledge this is the first practical threshold assessment for BVID detection on aerospace-grade CFRP for such sensors. We have put our detection thresholds to the test by analysing a total of 24 BVIDs on 12 panels made from 4 different CFRP material systems and derived commendable sizes for the detection range on the different material systems

Resuming elective hip and knee arthroplasty after the first phase of the SARS-CoV-2 pandemic: the European Hip Society and European Knee Associates recommendations

The Covid-19 pandemic has disrupted health care systems all over the world. Elective surgical procedures have been postponed and/or cancelled. Consensus is, therefore, required related to the factors that need to be in place before elective surgery, including hip and knee replacement surgery, which is restarted. Entirely new pathways and protocols need to be worked out. Methods A panel of experts from the European Hip Society and European Knee Association have agreed to a consensus statement on how to reintroduce elective arthroplasty surgery safely. The recommendations are based on the best available evidence and have been validated in a separate survey. Results The guidelines are based on five themes: modification and/or reorganisation of hospital wards. Restrictions on orthopaedic wards and in operation suite(s). Additional disinfection of the environment. The role of ultra-clean operation theatres. Personal protective equipment enhancement. Conclusion Apart from the following national and local guidance, protocols need to be put in place in the patient pathway for primary arthroplasty to allow for a safe retur

Recommendations for resuming elective hip and knee arthroplasty in the setting of the SARS‑CoV‑2 pandemic: the European Hip Society and European Knee Associates Survey of Members

The COVID-19 pandemic has disrupted the health care system around the entire globe. A consensus is needed about resuming total hip and knee procedures. The European Hip Society (EHS) and the European Knee Association (EKA) formed a panel of experts that have produced a consensus statement on how the safe re-introduction of elective hip and knee arthroplasty should be undertaken. Methods A prospective online survey was done among members of EHS and EKA. The survey consisted of 27 questions. It includes basic information on demographics and details the participant’s agreement with each recommendation. The participant could choose among three options (agree, disagree, abstain). Recommendations focussed on pre-operative, perioperative, and post-operative handling of patients and precautions. Results A total of 681 arthroplasty surgeons participated in the survey, with 479 fully completing the survey. The participants were from 44 countries and 6 continents. Apart from adhering to National and Local Guidelines, the recommendations concerned how to make elective arthroplasty safe for patients and staf. Conclusion The survey has shown good-to-excellent agreement of the participants with regards to the statements made in the recommendations for the safe return to elective arthroplasty following the frst wave of the COVID-19 pandemi