Fidelity and visibility reduction in Majorana qubits by entanglement with environmental modes

We study the dynamics and readout of topological qubits encoded by zero-energy Majorana bound states in a topological superconductor. We take into account bosonic modes due to the electromagnetic environment which couple the Majorana manifold to above-gap continuum quasi-particles. This coupling causes the degenerate ground state of the topological superconductor to be dressed in a polaron-like manner by quasi-particle states and bosons, and the system to become gapless. Topological protection and hence full coherence is only maintained if the qubit is operated and read out within the low-energy spectrum of the dressed states. We discuss reduction of fidelity and/or visibility if this condition is violated by a quantum-dot readout that couples to the bare (undressed) Majorana modes. For a projective measurement of the bare Majorana basis, we formulate a Bloch-Redfield approach that is valid for weak Majorana-environment coupling and takes into account constraints imposed by fermion-number-parity conservation. Within the Markovian approximation, our results essentially confirm earlier theories of finite-temperature decoherence based on Fermi's golden rule. However, the full non-Markovian dynamics reveals, in addition, the fidelity reduction by a projective measurement. Using a spinless nanowire model with $p$-wave pairing, we provide quantitative results characterizing these effects.Comment: 18 pages, 10 figure

Analyzing Short-Term Noise Dependencies of Spike-Counts in Macaque Prefrontal Cortex Using Copulas and the Flashlight Transformation

Simultaneous spike-counts of neural populations are typically modeled by a Gaussian distribution. On short time scales, however, this distribution is too restrictive to describe and analyze multivariate distributions of discrete spike-counts. We present an alternative that is based on copulas and can account for arbitrary marginal distributions, including Poisson and negative binomial distributions as well as second and higher-order interactions. We describe maximum likelihood-based procedures for fitting copula-based models to spike-count data, and we derive a so-called flashlight transformation which makes it possible to move the tail dependence of an arbitrary copula into an arbitrary orthant of the multivariate probability distribution. Mixtures of copulas that combine different dependence structures and thereby model different driving processes simultaneously are also introduced. First, we apply copula-based models to populations of integrate-and-fire neurons receiving partially correlated input and show that the best fitting copulas provide information about the functional connectivity of coupled neurons which can be extracted using the flashlight transformation. We then apply the new method to data which were recorded from macaque prefrontal cortex using a multi-tetrode array. We find that copula-based distributions with negative binomial marginals provide an appropriate stochastic model for the multivariate spike-count distributions rather than the multivariate Poisson latent variables distribution and the often used multivariate normal distribution. The dependence structure of these distributions provides evidence for common inhibitory input to all recorded stimulus encoding neurons. Finally, we show that copula-based models can be successfully used to evaluate neural codes, e. g., to characterize stimulus-dependent spike-count distributions with information measures. This demonstrates that copula-based models are not only a versatile class of models for multivariate distributions of spike-counts, but that those models can be exploited to understand functional dependencies

On reconciling ground-based with spaceborne normalized radar cross section measurements

©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.This study examines differences in the normalized radar cross section, derived from ground-based versus spaceborne radar data. A simple homogeneous half-space model, indicates that agreement between the two improves as 1) the distance from the scatterer is increased; and/or 2) the extinction coefficient increases

Ptychographic X-ray computed tomography of extended colloidal networks in food emulsions

As a main structural level in colloidal food materials, extended colloidal networks are important for texture and rheology. By obtaining the 3D microstructure of the network, macroscopic mechanical properties of the material can be inferred. However, this approach is hampered by the lack of suitable non-destructive 3D imaging techniques with submicron resolution. We present results of quantitative ptychographic X-ray computed tomography applied to a palm kernel oil based oil-in-water emulsion. The measurements were carried out at ambient pressure and temperature. The 3D structure of the extended colloidal network of fat globules was obtained with a resolution of around 300 nm. Through image analysis of the network structure, the fat globule size distribution was computed and compared to previous findings. In further support, the reconstructed electron density values were within 4% of reference values.Comment: 19 pages, 4 figures, to be published in Food Structur

Employing combination procedures to short-time EOP prediction

A well known problem with Earth Orientation Parameters (EOP) prediction is that a prediction strategy proved to be the best for some testing time span and prediction length may not remain the same for other time intervals. In this paper, we consider possible strategies to combine EOP predictions computed using different analysis techniques to obtain a final prediction with the best accuracy corresponding to the smallest prediction error of input predictions. It was found that this approach is most efficient for ultra-short-term EOP forecast.Comment: 7 pages, presented at the IERS Workshop on EOP Combination and Prediction, Warsaw, Poland, 19-21 Oct 200

Parity-to-charge conversion in Majorana qubit readout

We study the time-dependent effect of Markovian readout processes on Majorana qubits whose parity degrees of freedom are converted into the charge of a tunnel-coupled quantum dot. By applying a recently established effective Lindbladian approximation [1-3], we obtain a completely positive and trace preserving Lindblad master equation for the combined dot-qubit dynamics, describing relaxation and decoherence processes beyond the rotating-wave approximation. This approach is applicable to a wide range of weakly coupled environments representing experimentally relevant readout devices. We study in detail the case of thermal decay in the presence of a generic Ohmic bosonic bath, in particular for potential fluctuations in an electromagnetic circuit. In addition, we consider the nonequilibrium measurement environment for a parity readout using a quantum point contact capacitively coupled to the dot charge.Comment: References updated in v2. 21 pages, 9 figure

Identifying Inconsistencies and Reporting Deficits in Therapeutic Massage and Bodywork (TMB) Case Reports: A Systematic Review and TMB Adapted CAse REport (CARE) Guidelines Audit

poster abstractIntroduction: Case reports are a fundamental tool through which practitioners in applied disciplines are able to inform research and impact their field by detailing the presentation, treatment, and follow-up of a single individual they’ve encountered in practice. Ideally, published case reports contribute to reductions in the research/practice gap by allowing practitioners to describe current practice situations and outcomes to researchers. Unfortunately, inconsistencies in case reporting across applied disciplines have limited the impact of these fundamental sources of clinical evidence. In 2013, reporting guidelines for case reports (CARE guidelines) were published to standardize the reporting of medical case reports. In recognition of discipline differences and reporting needs, the therapeutic massage and bodywork (TMB) adapted CARE guidelines were published in late 2014 to specifically guide reporting of case reports involving massage therapy applied as a treatment. The TMB adapted CARE guidelines identified 5 primary case report components (pre-manuscript, Introduction, Case Presentation, Results, and Discussion), each with unique subcomponents (e.g., title, keywords, abstract for the pre-manuscript component) ranging in number from 6 - 31. By checking off each component and subcomponent included in any given case report, a summary score for TMB adapted CARE guidelines compliance (range: 0 – 65) can be derived. In order to determine whether the consistency of TMB case reporting is improved after publication of the TMB adapted CARE guidelines, a pre-guideline state of TMB case reports is needed. The current study seeks to provide rich descriptive statistics about the state of TMB related case reports in the literature prior to 2015. Methods: A systematic review using PubMed and CINAHL databases identified 935 unique citations using first the MeSH term “Therapy, Soft Tissue” as the subject heading and publication type “case reports” and then a keyword search in PubMed (acupressure, shiatsu, zhi ya, chih ya, reflexology, rolfing, bodywork, massage, case report, case reports, case study, case studies NOT carotid sinus massage, heart massage, cardiac massage, animals) and CINAHL (subject headings: massage therapists, massage, reflexology, case study). Study inclusion/exclusion criteria required: case report, human, English, peer-reviewed, published prior to 2015. Administered massage treatment(s) had to have been from a professional TMB practitioner who had a role in the case’s reporting and publication. N=34 articles met inclusion criteria and were reviewed by two independent reviewers. Through a REDCap data collection form, components and subcomponents of the TMB adapted CARE reporting guidelines included in each article were identified. Variable coding and descriptive statistics were completed using SAS 9.3 by a non-reviewing team member. TMB adapted CARE reporting compliance scores were determined for each case report. Results: Preliminary results for n=30 (final presentation to include all N=34) indicate mean compliance scores = 40.3 (±9.2) and ranged from 10-50. Article sections with the most robust scoring included pre-manuscript items and introduction with average section scores obtaining 75% and 70% of the possible points, respectively. Case presentation and results sections scored the poorest, obtaining an average of 58% and 53% of the possible points, respectively. Conclusions: Case reports in the TMB field published before possible exposure to the TMB adapted CARE guidelines demonstrate inconsistent and deficient reporting. If case reports in the TMB field are to have an impact, consistent and rigorous reporting must be adopted. In an effort to improve the state and impact of TMB case reports in the literature, TMB practitioners should use the TMB adapted CARE guidelines as a checklist when preparing their case reports for publication

Identifying Inconsistencies and Reporting Deficits in Therapeutic Massage and Bodywork (TMB) Case Reports Authored by TMB Practitioners: a TMB-Adapted CAse REport (CARE) Guidelines Audit Through 2014

INTRODUCTION: Case reports are a fundamental tool through which therapeutic massage and bodywork (TMB) practitioners can inform research and impact their field by detailing the presentation, treatment, and follow-up of a single individual encountered in practice. Inconsistencies in case reporting limit their impact as fundamental sources of clinical evidence. Using the TMB-adapted CAse REport (CARE) guidelines, the current study sought to provide a rich description regarding the reporting quality of TMB practitioner authored TMB case reports in the literature. METHODS: 1) Systematic identification of published, peer-reviewed TMB case reports authored by TMB practitioners following PRISMA recommendations; 2) audit development based on TMB-adapted CARE guidelines; 3) audit implementation; and 4) descriptive analysis of audit scores. RESULTS: Our search identified 977 articles and 35 met study inclusion criteria. On average, TMB case reports included approximately 58% of the total items identified as necessary by the TMB-adapted CARE guidelines. Introduction sections of case reports had the best item reporting (80% on average), while Case Presentation (54%) and Results (52%) sections scored moderately overall, with only 20% of necessary Practitioner Description items included on average. Audit scores revealed inconsistent abstract reporting and few audited case reports including client race (20%), perspective (26%), and occupation/activities (40%); practitioner practice setting (12%), training (12%), scope-of-practice (29%), and credentialing (20%); adverse events or lack thereof (17%); and some aspect of informed consent (34%). Treatment descriptor item reporting varied from high to low. Various implications of concern are discussed. CONCLUSION: The current audit and descriptive analysis highlight several reporting inconsistencies in TMB case reports prior to 2015. Reporting guidelines for case reports are important if standards for, and impact of, TMB case reports are desired. Adherence to reporting specifications outlined by the TMB-adapted CARE guidelines could improve the impact and usability of TMB case reports in research, education, and practice