1,441 research outputs found

    Jacobi Crossover Ensembles of Random Matrices and Statistics of Transmission Eigenvalues

    Full text link
    We study the transition in conductance properties of chaotic mesoscopic cavities as time-reversal symmetry is broken. We consider the Brownian motion model for transmission eigenvalues for both types of transitions, viz., orthogonal-unitary and symplectic-unitary crossovers depending on the presence or absence of spin-rotation symmetry of the electron. In both cases the crossover is governed by a Brownian motion parameter {\tau}, which measures the extent of time-reversal symmetry breaking. It is shown that the results obtained correspond to the Jacobi crossover ensembles of random matrices. We derive the level density and the correlation functions of higher orders for the transmission eigenvalues. We also obtain the exact expressions for the average conductance, average shot-noise power and variance of conductance, as functions of {\tau}, for arbitrary number of modes (channels) in the two leads connected to the cavity. Moreover, we give the asymptotic result for the variance of shot-noise power for both the crossovers, the exact results being too long. In the {\tau} \rightarrow 0 and {\tau} \rightarrow \infty limits the known results for the orthogonal (or symplectic) and unitary ensembles are reproduced. In the weak time-reversal symmetry breaking regime our results are shown to be in agreement with the semiclassical predictions.Comment: 24 pages, 5 figure

    Crystallographic and magnetic identification of secondary phase in orientated Bi5Fe0.5Co0.5Ti3O15 ceramics

    Get PDF
    Oxide materials which exhibit both ferroelectricity and ferromagnetism are of great interest for sensors and memory applications. Layered bismuth titanates with an Aurivillius structure, (BiFeO3)nBi4Ti3O12, can possess ferroelectric and ferromagnetic order parameters simultaneously. It has recently been demonstrated that one such example, Bi5Fe0.5Co0.5Ti3O15,where n = 1 with half the Fe3+ sites substituted by Co3+ ions, exhibits both ferroelectric and ferromagnetic properties at room temperature. Here we report the fabrication of highly-oriented polycrystalline ceramics of this material, prepared via molten salt synthesis and uniaxial pressing of high aspect ratio platelets. Electron backscatter images showed that there is a secondary phase within the ceramic matrix which is rich in cobalt and iron, hence this secondary phase could contribute in the main phase ferromagnetic property. The concentration of the secondary phase obtained from secondary electron microscopy is estimated at less than 2.5 %, below the detection limit of XRD. TEM was used to identify the crystallographic structure of the secondary phase, which was shown to be cobalt ferrite, CoFe2O4. It is inferred from the data that the resultant ferromagnetic response identified using VSM measurements was due to the presence of the minor secondary phase. The Remanent magnetization at room temperature was Mr ≈ 76 memu/g which dropped down to almost zero (Mr ≈ 0.8 memu/g) at 460 oC, far lower than the anticipated for CoFe2O4

    A Case Study Concerning The Effects Of Controller Response And Turning Movements On Application Rate Uniformity With A Self-Propelled Sprayer

    Get PDF
    The use of precision agriculture technologies such as automatic boom section control allows producers to reduce off-target application when applying herbicides. While automatic boom section control provides benefits, pressure differences across the spray boom resulting from boom section actuation may lead to off-rate application errors. Off-rate errors may also result from spray rate controller compensation for ground speed changes or velocity variation across the spray boom during turning movements. This project focused on characterizing application rate variation for three fields located in central Kentucky. GPS coordinates, boom control status, and nozzle pressure data (at 15 nozzle locations) were recorded as the sprayer traversed the study fields. Control section coverage areas and nozzle flow rates (calculated from the nozzle pressure with manufacturer calibration data) were used to estimate application rates. Results indicated the majority of each field received application rates at or below the target rate, as only 25% to 36% of the area in the study fields received application rates within the target rate ±10%. Spray rate controller lag time appeared to contribute to lower application rates as the sprayer accelerated and higher application rates as the sprayer decelerated as the controller attempted to compensate for changes in sprayer velocity. In addition, as boom control sections were turned off, pressure increases in the remaining sections resulted in higher application rates. Conversely, as boom sections were turned on, spray rate controller lag time may have contributed to lower application rates. Estimated application rate maps were also generated from the data to allow for a visual summary of the potential errors

    Measuring Quality: The Impact of Minimally Invasive Surgery and Operative Time on Surgical Site Infections

    Get PDF
    Objective: To evaluate the relationship between operative approach, operative time, and SSI rate.Methods: Inpatient database review identified patients undergoing 5 common procedures from 1/2010-12/2011. Patients were stratified into laparoscopic or open approaches. The main outcome measure was the relationship between operative time and SSI by approach.Results: 226,006 patients were evaluated- 28.2% open and 71.8% laparoscopic. Mean overall operative time was significantly shorter laparoscopically (p<0.001). Laparoscopy was associated with significantly lower costs and shorter length of stay (LOS) overall and for each procedure(p<0.0001). Multivariate analysis found SSI increased directly with operative time: for every 30-minute increase, SSI risk increased by 12%. Operative approach was an independent risk factor for SSI: open surgery increased SSI risk by 78%. A direct relationship between open procedures, operative time, and SSI risk was found.Conclusions: Laparoscopy has overall shorter operative time and improved outcomes in SSI rate, LOS, and total costs for common surgical procedures. As operative time and approach were independent risk factors for SSI, the use of laparoscopy and operative time are valuable quality measures

    Vibration based electromagnetic micropower generator on silicon

    Get PDF
    This paper discusses the theory, design and simulation of electromagnetic micropower generators with electroplated micromagnets. The power generators are fabricated using standard microelectromechanical system processing techniques. Electromagnetic two-dimensional finite element anlysis simulations are used to determine voltage and power that can be generated from different designs. This paper reports a maximum voltage and power of 55 mV and 70 mu W for the first design, incorporating microfabricated two-layer Cu coils on a Si paddle vibrating between two sets of oppositely polarized electroplated Co50Pt50 face centered tetragonal phase hard magnets. A peak voltage and power of 950 mV and 85 mu W are obtained for the second design, which includes electroplated Ni45Fe55 as a soft magnetic layer underneath the hard magnets. The volume of the device is about 30 mm(3)

    Tinea incognito with unjustified use of potent Topical Corticosteroids: a case series

    Get PDF
    Topical corticosteroids prescribed for various dermatological conditions, if used haphazardly have their adverse effects too, like aggravation of underlying infections - tinea, herpes etc. Tinea incognito is a fungal infection of skin masked and often exacerbated by application of topical immunosuppressive or steroid agent. Tinea incognito results because local physicians/chemists might mistake tinea with a simple rash. Availability of a topical steroid cream as an over the counter (OTC) drug is also one of the causes. Once it is diagnosed (clinically with or without KOH mount preparation), it should be thoroughly treated with oral and topical antifungal agents. Four cases presenting to Dermatology OPD VSGH with chief complaints of itching and aggravation of existing lesions due to application of potent topical corticosteroids like Clobetasol and Beclomethasone have been discussed here. They were diagnosed as cases of Topical Corticosteroids induced Tinea Incognito. The patients were recovering with oral and topical antifungals prescribed by dermatologist. These were also reported to nearest ADR Monitoring Centre under PvPI with Probable causality according to WHO UMC Criteria for Causality Assessment. The wide use of topical corticosteroids is due to its immediate symptomatic relief. However, the normal presentation of superficial infection gets altered with their inappropriate use. Lack of awareness among population, steroid abuse by local physicians or no strict regulations for local chemist shops have led to its inappropriate use. Its incidence ranges from 5-15%. These figures point towards the fact that implementation of appropriate regulations for the safe use of topical corticosteroids is essential

    The construction and validation of a short form of the developmental, diagnostic and dimensional interview

    Full text link
    We aimed to construct and validate a shortened form of the developmental, diagnostic and dimensional interview (3Di), a parent report interview for assessing and diagnosing autistic spectrum disorders (ASDs). Data from 879 children and young people were used. In half of the sample (n = 440) reliability analysis was used to identify 3Di items that best measured each dimension of the autism triad. This informed the construction of a shortened (53 item) 3Di, which was then validated on subjects not used in the reliability analysis (n = 439). This involved comparison with scores from the original 3Di algorithm and, in a subsample (n = 29), with the autism diagnostic interview-revised (ADI-R). Agreement of the new shortened 3Di with the 3Di’s original algorithm was excellent in both dimensional and categorical terms. Agreement on caseness (27 out of 29) with the ADI-R was also strong. The new 3Di short version is less than half as long as the original version and outputs very similar scores. It will be useful to clinicians and researchers for obtaining a dimensional autism assessment in less than 45 minutes

    A Correlative Study Between Size of Tympanic Membrane Perforation, Pure Tone Audiometry and Intraoperative Findings in Tympanoplasty

    Get PDF
    Introduction             Chronic otitis media (COM) is a most common and prevalent disease of the middle ear. COM has been defined as a longstanding inflammatory condition of middle ear and mastoid, associated with perforation of the tympanic membrane. Tympanoplasties are common surgeries performed for chronic otitis media in inactive mucosal type. Any otological surgery may involve a menace/ hazard of hearing loss post operatively.             In this study, an attempt was made to correlate, size of tympanic membrane perforation, pure tone audiometry and intra-operative findings in tympanoplasties, results were analysed and conclusion drawn. Materials and Methods Forty patients attending ENT OPD with chronic otitis media (COM), inactive mucosal type, with conductive hearing loss undergoing tympanoplasties who were willing to participate in the study were selected.  Ear was examined pre-operatively to assess the size of perforation and then, pure tone audiometry (PTA) was done to assess the type of hearing loss and its severity. During tympanoplasty, middle ear was inspected for ossicular status and any other pathology was noted. Later, the size of tympanic membrane perforation, pure tone audiometry and intra operative findings were correlated with each other and analysed. Result  In small and medium sized perforation, PTA and intraoperative findings correlated with each other. Whereas, in large and subtotal perforation, there was no correlation. Conclusion             In small and medium sized perforation, middle ear inspection may not be necessary. Whereas, in large and subtotal perforation it is necessary

    Protocol for the development and validation procedure of the managing the link and strengthening transition from child to adult mental health care (MILESTONE) suite of measures

    Get PDF
    Background: Mental health disorders in the child and adolescent population are a pressing public health concern. Despite the high prevalence of psychopathology in this vulnerable population, the transition from Child and Adolescent Mental Health Services (CAMHS) to Adult Mental Health Services (AMHS) has many obstacles such as deficiencies in planning, organisational readiness and policy gaps. All these factors contribute to an inadequate and suboptimal transition process. A suite of measures is required that would allow young people to be assessed in a structured and standardised way to determine the on-going need for care and to improve communication across clinicians at CAMHS and AMHS. This will have the potential to reduce the overall health economic burden and could also improve the quality of life for patients travelling across the transition boundary. The MILESTONE (Managing the Link and Strengthening Transition from Child to Adult Mental Health Care) project aims to address the significant socioeconomic and societal challenge related to the transition process. This protocol paper describes the development of two MILESTONE transition-related measures: The Transition Readiness and Appropriateness Measure (TRAM), designed to be a decision-making aide for clinicians, and the Transition Related Outcome Measure (TROM), for examining the outcome of transition. Methods: The TRAM and TROM have been developed and were validated following the US FDA Guidance for Patient-reported Outcome Measures which follows an incremental stepwise framework. The study gathers information from service users, parents, families and mental health care professionals who have experience working with young people undergoing the transition process from eight European countries. Discussion: There is an urgent need for comprehensive measures that can assess transition across the CAMHS/AMHS boundary. This study protocol describes the process of development of two new transition measures: the TRAM and TROM. The TRAM has the potential to nurture better transitions as the findings can be summarised and provided to clinicians as a clinician-decision making support tool for identifying cases who need to transition and the TROM can be used to examine the outcomes of the transition process. Trial registration: MILESTONE study registration: ISRCTN83240263 Registered 23-July-2015 - ClinicalTrials.gov NCT03013595 Registered 6 January 2017
    • 

    corecore