Harmonic oscillations and their switching in elliptical optical waveguide arrays

We have studied harmonic oscillations in an elliptical optical waveguide array in which the coupling between neighboring waveguides is varied in accord with a Kac matrix so that the propagation constant eigenvalues can take equally spaced values. As a result, long-living Bloch oscillation (BO) and dipole oscillation (DO) are obtained when a linear gradient in the propagation constant is applied. Moreover, we achieve a switching from DO to BO or vice versa by ramping up the gradient profile. The various optical oscillations as well as their switching are investigated by field evolution analysis and confirmed by Hamiltonian optics. The equally spaced eigenvalues in the propagation constant allow viable applications in transmitting images, switching and routing of optical signals.Comment: 14 pages, 5 figure

Schrodinger cat states prepared by Bloch oscillation in a spin-dependent optical lattice

We propose to use Bloch oscillation of ultra-cold atoms in a spin-dependent optical lattice to prepare schrodinger cat states. Depending on its internal state, an atom feels different periodic potentials and thus has different energy band structures for its center-of-mass motion. Consequently, under the same gravity force, the wave packets associated with different internal states perform Bloch oscillation of different amplitudes in space and in particular they can be macroscopically displaced with respect to each other. In this way, a cat state can be prepared.Comment: 4 pages, 3 figures; slightly modifie

Can auditors be independent? – Experimental evidence on the effects of client type

Recent regulatory initiatives stress that an independent oversight board, rather than the management board, should be the client of the auditor. In an experiment, we test whether the type of client affects auditors’ independence. Unique features of the German institutional setting enable us to realistically vary the type of auditors’ client as our treatment variable: we portray the client either as the management preferring aggressive accounting or the oversight board preferring conservative accounting. We measure auditors’ perceived client retention incentives and accountability pressure in a post-experiment questionnaire to capture potential threats to independence. We find that the type of auditors’ client affects auditors’ behaviour contingent on the degree of the perceived threats to independence. Our findings imply that both client retention incentives and accountability pressure represent distinctive threats to auditors’ independence and that the effectiveness of an oversight board in enhancing auditors’ independence depends on the underlying threat

The management of paediatric diaphyseal femoral fractures: a modern approach.

The definitive treatment of paediatric femoral diaphyseal fractures remains controversial. Modalities of treatment vary mostly according to age, with fracture pattern and site having a lesser impact. Current evidence is reflective of this variation with most evidence cited by the American Academy of Orthopedic Surgeons being level 4 or 5. The authors present a review of the most up-to-date evidence relating to the treatment of these fractures in each age group. In an attempt to clarify the current trends, we have produced an algorithm for decision-making based on the experience from our own tertiary referral level 1 major trauma centre

A systematic review of tourniquet use in paediatric orthopaedic surgery: can we extrapolate from adult guidelines?

PURPOSE: Tourniquets are commonly used intraoperatively in orthopaedic surgery to control bleeding and improve visibility in the surgical field. Recent evidence has thrown into question the routine use of tourniquets in the adult population resulting in a British Orthopaedic Association standard for intraoperative use. This systematic review evaluates the evidence on the practice, benefits, and risks of the intraoperative use of tourniquets for trauma and elective orthopaedic surgery in the paediatric population. METHODS: A prospectively registered systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO: CRD42022359048). A search of MEDLINE, Embase, the Cochrane Library and a Grey literature search was performed from their earliest record to 23 March 2023. Studies reporting tourniquet data in paediatric patients undergoing orthopaedic surgery were included. Data extracted included demographics, involved limb, trauma versus elective use, tourniquet use as primary or secondary measure, and tourniquet parameters and complications. RESULTS: Thirty-nine studies were included. Tourniquet practices and information reporting varied considerably. Tourniquets were used uneventfully in the majority of patients with no specific benefits reported. Several physiological and biochemical changes as well as complications including nerve injury, compartment syndrome, skin burns, thrombosis, post-operative limb swelling, and pain were reported. CONCLUSIONS: Tourniquets are routinely used in both trauma and elective paediatric orthopaedic surgery with no high-quality research affirming benefits. Severe complications associated with their use are rare but do occur. High-quality studies addressing their benefits, the exact indication in children, and the safest way to use them in this population are necessary

Association of cyberbullying victimization and substance initiation: The Adolescent Brain Cognitive Development (ABCD) study

BackgroundEvidence shows that cyberbullying is an important risk factor for various adverse mental health outcomes, such as substance use. However, there is limited evidence from longitudinal studies that assessed whether cyberbullying victimization is associated with substance use initiation, especially among adolescent population.MethodsUsing data from the Adolescent Brain Cognitive Development Study, we assessed the association between cyberbullying victimization and substance use initiation among adolescents. In the cross-sectional analysis at year 2, multivariable logistic regressions were used to assess the association between cyberbullying victimization history and substance use initiation. Additionally, the association between year 2 cyberbullying victimization in the past 12 months/lifetime and year 3 substance use initiation was assessed using multivariable logistic regression.ResultsAdjusting for sociodemographic characteristics and the presence of depression/anxiety symptoms, lifetime history of cyberbullying victimization was significantly associated with substance use initiation (OR= 2.17, 95% CI: 1.68, 2.81). Recent cyberbullying victimization in the past 12 months was associated with two-times higher odds of initiating substances (OR= 2.31, 95% CI: 1.71, 3.12). In addition, both lifetime history of cyberbullying victimization and recent cyberbullying victimization at year 2 were associated with two times increased risk in substance use initiation at year 3 (OR = 2.22, 95% CI: 1.68, 2.93; OR = 2.34, 95% CI: 1.68, 3.26).ConclusionThere is a significant relationship between cyberbullying victimization and substance use initiation among adolescents. Cyberbullying victims are at an increased risk of initiating substance use later in life

Guideline on the peri-operative management of patients with sickle cell disease: Guideline from the Association of Anaesthetists

Sickle cell disease is a multisystem disease characterised by chronic haemolytic anaemia, painful vaso-occlusive crises and acute and chronic end-organ damage. It is one of the most common serious inherited single gene conditions worldwide and has a major impact on the health of affected individuals. Peri-operative complications are higher in patients with sickle cell disease compared with the general population and may be sickle or non-sickle-related. Complications may be reduced by meticulous peri-operative care and transfusion, but unnecessary transfusion should be avoided, particularly to reduce the risk of allo-immunisation. Planned surgery and anaesthesia for patients with sickle cell disease should ideally be undertaken in centres with experience in caring for these patients. In an emergency, advice should be sought from specialists with experience in sickle cell disease through the haemoglobinopathy network arrangements. Emerging data suggest that patients with sickle cell disease are at increased risk of COVID-19 infection but may have a relatively mild clinical course. Outcomes are determined by pre-existing comorbidities, as for the general population

The influence of “kickstand” screws on the mechanical performance of a lateral distal femoral plate

Aims Lateral locked plating of distal femoral fractures is widely reported, yet there remains a 9% to 19% incidence of mechanical failure. Obliquely directed “kickstand screws”, from the metaphyseal portion of a plate toward far-sided articular subchondral bone, have been shown to improve construct stiffness. This study explores the impact of kickstand screws in a finite element analysis bone defect model, comparing plate and screw maximum stress and maximum locking screw forces either with or without the addition of kickstand screws. Methods A finite element analysis model of a lateral based femoral plate and fracture gap simulation was created, with material and construct data parameters regarding bone material, implant, and composite model identified. The addition of the upper, lower, or both kickstand screws in an anatomical precontoured lateral distal femoral plate were selected as the variables compared against the absence of kickstand screws. Screw and plate principal stresses (MPa) and locking screw mechanism force (N) were measured. Results The addition of the upper kickstand screw or both kickstand screws led to an approximate 40% reduction of stress in the metaphyseal hole closest to the fracture. The addition of the lower, upper, and both kickstand screws led to a 23%, 32%, and 34% reduction of maximum stress in the metaphyseal screws, respectively. The addition of the lower kickstand screw led to a 19% reduction, while the upper or both kickstand screws led to a 23% reduction of maximum force experienced by the locking mechanism. Conclusion The addition of kickstand screws improves the mechanical performance of the construct, with reduced stresses experienced by the plate and metaphyseal screws. Furthermore, the maximum forces on the locking screw mechanism were shown to be significantly reduced, providing a protective effect to the polyaxial locking mechanism of the metaphyseal screw. Cite this article: Bone Joint Res 2025;14(8):713–720

Solitons in one-dimensional nonlinear Schr\"{o}dinger lattices with a local inhomogeneity

In this paper we analyze the existence, stability, dynamical formation and mobility properties of localized solutions in a one-dimensional system described by the discrete nonlinear Schr\"{o}dinger equation with a linear point defect. We consider both attractive and repulsive defects in a focusing lattice. Among our main findings are: a) the destabilization of the on--site mode centered at the defect in the repulsive case; b) the disappearance of localized modes in the vicinity of the defect due to saddle-node bifurcations for sufficiently strong defects of either type; c) the decrease of the amplitude formation threshold for attractive and its increase for repulsive defects; and d) the detailed elucidation as a function of initial speed and defect strength of the different regimes (trapping, trapping and reflection, pure reflection and pure transmission) of interaction of a moving localized mode with the defect.Comment: 12 pages, 10 figure