Multiphoton localization and propagating quantum gap solitons in a frequency gap medium

The many-particle spectrum of an isotropic frequency gap medium doped with impurity resonance atoms is studied using the Bethe ansatz technique. The spectrum is shown to contain pairs of quantum correlated ``gap excitations'' and their heavy bound complexes (``gap solitons''), enabling the propagation of quantum information within the classically forbidden gap. In addition, multiparticle localization of the radiation and the medium polarization occurs when such a gap soliton is pinned to the impurity atom.Comment: 8 pages, RevTEX, to appear in Phys. Rev. Let

Test for interlayer coherence in a quasi-two-dimensional superconductor

Peaks in the magnetoresistivity of the layered superconductor $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$, measured in fields $\leq 45$ T applied within the layers, show that the Fermi surface is extended in the interlayer direction and enable the interlayer transfer integral ($t_{\perp} \approx 0.04$ meV) to be deduced. However, the quasiparticle scattering rate $\tau^{-1}$ is such that $\hbar/\tau \sim 6t_{\perp}$, implying that $\kappa$-(BEDT-TTF)$_2$Cu(NCS)$_2$ meets the criterion used to identify interlayer incoherence. The applicability of this criterion to anisotropic materials is thus shown to be questionable.Comment: 5 pages, 4 figure

On the de Haas-van Alphen effect in inhomogeneous alloys

We show that Landau level broadening in alloys occurs naturally as a consequence of random variations in the local quasiparticle density, without the need to consider a relaxation time. This approach predicts Lorentzian-broadened Landau levels similar to those derived by Dingle using the relaxation-time approximation. However, rather than being determined by a finite relaxation time $\tau$, the Landau-level widths instead depend directly on the rate at which the de Haas-van Alphen frequency changes with alloy composition. The results are in good agreement with recent data from three very different alloy systems.Comment: 5 pages, no figure

Shot noise and spin-orbit coherent control of entangled and spin polarized electrons

We extend our previous work on shot noise for entangled and spin polarized electrons in a beam-splitter geometry with spin-orbit (\textit{s-o}) interaction in one of the incoming leads (lead 1). Besides accounting for both the Dresselhaus and the Rashba spin-orbit terms, we present general formulas for the shot noise of singlet and triplets states derived within the scattering approach. We determine the full scattering matrix of the system for the case of leads with \textit{two} orbital channels coupled via weak \textit{s-o} interactions inducing channel anticrossings. We show that this interband coupling coherently transfers electrons between the channels and gives rise to an additional modulation angle -- dependent on both the Rashba and Dresselhaus interaction strengths -- which allows for further independent coherent control of the electrons traversing the incoming leads. We derive explicit shot noise formulas for a variety of correlated pairs (e.g., Bell states) and lead spin polarizations. Interestingly, the singlet and \textit{each} of the triplets defined along the quantization axis perpendicular to lead 1 (with the local \textit{s-o} interaction) and in the plane of the beam splitter display distinctive shot noise for injection energies near the channel anticrossings; hence, one can tell apart all the triplets, in addition to the singlet, through noise measurements. We also find that spin-orbit induced backscattering within lead 1 reduces the visibility of the noise oscillations, due to the additional partition noise in this lead. Finally, we consider injection of two-particle wavepackets into leads with multiple discrete states and find that two-particle entanglement can still be observed via noise bunching and antibunching.Comment: 30 two-column pages and 7 figure

Gain-of-Function Mutations in the K_ATP Channel (KCNJ11) Impair Coordinated Hand-Eye Tracking

Background: Gain-of-function mutations in the ATP-sensitive potassium channel can cause permanent neonatal diabetes mellitus (PNDM) or neonatal diabetes accompanied by a constellation of neurological symptoms (iDEND syndrome). Studies of a mouse model of iDEND syndrome revealed that cerebellar Purkinje cell electrical activity was impaired and that the mice exhibited poor motor coordination. In this study, we probed the hand-eye coordination of PNDM and iDEND patients using visual tracking tasks to see if poor motor coordination is also a feature of the human disease.Methods: Control participants (n = 14), patients with iDEND syndrome (n = 6 or 7), and patients with PNDM (n = 7) completed three computer-based tasks in which a moving target was tracked with a joystick-controlled cursor. Patients with PNDM and iDEND were being treated with sulphonylurea drugs at the time of testing.Results: No differences were seen between PNDM patients and controls. Patients with iDEND syndrome were significantly less accurate than controls in two of the three tasks. The greatest differences were seen when iDEND patients tracked blanked targets, i.e. when predictive tracking was required. In this task, iDEND patients incurred more discrepancy errors (p = 0.009) and more velocity errors (p  = 0.009) than controls.Conclusions: These results identify impaired hand-eye coordination as a new clinical feature of iDEND. The aetiology of this feature is likely to involve cerebellar dysfunction. The data further suggest that sulphonylurea doses that control the diabetes of these patients may be insufficient to fully correct their neurological symptoms.</p

Quantum statistical effects in nano-oscillator arrays

We have theoretically predicted the density of states(DOS), the low temperature specific heat, and Brillouin scattering spectra of a large, free standing array of coupled nano-oscillators. We have found significant gaps in the DOS of 2D elastic systems, and predict the average DOS to be nearly independent of frequency over a broad band f < 50GHz. At low temperatures, the measurements probe the quantum statistics obeyed by rigid body modes of the array and, thus, could be used to verify the quantization of the associated energy levels. These states, in turn, involve center-of mass motion of large numbers of atoms, N > 1.e14, and therefore such observations would extend the domain in which quantum mechanics has been experimentally tested. We have found the required measurement capability to carry out this investigation to be within reach of current technology.Comment: 1 tex file, 3 figures, 1 bbl fil

Predicting risk of dementia with machine learning and survival models using routine primary care records

Worldwide, it is forecasted that 131.5 million people will suffer from dementia by 2050, and the annual cost of care will increase from 818 billion USD in 2016 to 2 trillion USD by 2030, with burgeoning social consequences. Given a timely prediction of a dementia outcome in patients, appropriate mitigating interventions can be applied to reduce risk. However such prediction facilities need to be made available to wider populations, and these facilities cannot rely on specialised, costly and invasive testing (such as neuroimaging, cerebrospinal fluid collection, etc which constitute important instruments used in diagnosis), for interventions to have a meaningful quantitative impact. Hence an emerging need exists for the wider application of prognostic measures which can be deployed using lower cost data sources such as longitudinal records routinely collected by general practices. This paper proposes an efficient prediction modelling approach to the risk of dementia, using CPRD data collected from GP practices in UK, and based on machine learning in particular the Gradient Boosting Machines model combined with a survival model such as the Cox Proportional Hazard, encapsulated in a semi-supervised learning and model calibration methodology

Measurements of the Casimir-Lifshitz force in fluids: the effect of electrostatic forces and Debye screening

In this work, we present detailed measurements of the Casimir-Lifshitz force between two gold surfaces (a sphere and a plate) immersed in ethanol and study the effect of residual electrostatic forces, which are dominated by static fields within the apparatus and can be reduced with proper shielding. Electrostatic forces are further reduced by Debye screening through the addition of salt ions to the liquid. Additionally, the salt leads to a reduction of the Casimir-Lifshitz force by screening the zero-frequency contribution to the force; however, the effect is small between gold surfaces at the measured separations and within experimental error. An improved calibration procedure is described and compared to previous methods. Finally, the experimental results are compared to Lifshitz's theory and found to be consistent for the materials used in the experiment.Comment: 11 figures. PRA in pres

Outcome measures for use in trials of paediatric otorrhoea:A systematic review

Introduction:Paediatric otorrhoea (PO) describes a middle ear infection that results in a perforation of the tympanic membrane and ear discharge, in children and young people (CYP). Prolonged infection may be associated with hearing loss and developmental delay. The current management of paediatric otorrhoea is variable, including non-invasive treatments (conservative, oral antibiotics, topical antibiotics) and surgery, reflecting the lack of a sufficiently strong evidence base. Outcome reporting is fundamental to producing reliable and meaningful evidence to inform best practice.Objectives:Primary objective: to determine which outcome measures are currently used to evaluate treatment success in studies of non-surgical treatments for paediatric otorrhoea. Secondary objectives: to identify outcome measurement instruments used in the literature and assess their applicability for use in clinical trials of PO.Methods:This systematic review was registered with PROSPERO (CRD42023407976). Database searches of EMBASE, MEDLINE and Cochrane was performed on June 6, 2023, covering from Jan 1995 to May 2023. Randomised controlled trials or study protocols involving CYP with PO were included following PRISMA guidelines. Risk of bias was assessed with Cochrane's tool.Results:Of the 377 papers identified, six were included in the systematic review. The primary outcome of five of the studies related to otorrhoea cessation; both time to cessation and proportion recovered at various time points were used as measures. Two measurement instruments were identified: Otitis Media-6 Questionnaire and the Institute for Medical Technology Assessment Productivity Cost Questionnaire. Both were shown to be applicable measurement instruments when used in clinical trials of PO.Conclusions:To promote homogeneity and facilitate meaningful comparison and combination of studies, we propose that time to cessation of otorrhoea from onset of otorrhoea should be used as the primary outcome in future studies. Further research is needed to establish if this is the most important outcome to children and their caregivers

Cyclotron motion in graphene

We investigate cyclotron motion in graphene monolayers considering both the full quantum dynamics and its semiclassical limit reached at high carrier energies. Effects of zitterbewegung due to the two dispersion branches of the spectrum dominate the irregular quantum motion at low energies and are obtained as a systematic correction to the semiclassical case. Recent experiments are shown to operate in the semiclassical regime.Comment: 6 pages, 1 figure include