540 research outputs found

    Extraction of lateral eigenmode properties in thin film bulk acoustic wave resonator from interferometric measurements

    Get PDF
    A heterodyne laser interferometer is used to study acoustic wave fields excited in a 1.8 GHz AlN thin film bulk acoustic waveresonator. The electrical response of the resonator exhibits a strong thickness resonance onto which spurious modes, caused by lateral standing plate waves, are superposed. Optical interferometermeasurements are used to extract dispersion curves of the laterally propagating waves responsible for the spurious responses. A discrete eigenmode spectrum due to the finite lateral dimensions of the resonator is observed. An equivalent circuit model for a multimode resonator is fitted to the mechanical resonator response extracted along a single curve in the dispersion diagram, and is used to determine properties, such as Q-values, of the individual lateral eigenmodes.Measuredwave field images, extracted dispersion curves, and the eigenmode spectrum with the model fitting results are presented.Peer reviewe

    Electroencephalogram approximate entropy influenced by both age and sleep

    Full text link
    The use of information-based measures to assess changes in conscious state is an increasingly popular topic. Though recent results have seemed to justify the merits of such methods, little has been done to investigate the applicability of such measures to children. For our work, we used the approximate entropy (ApEn), a measure previously shown to correlate with changes in conscious state when applied to the electroencephalogram (EEG), and sought to confirm whether previously reported trends in adult ApEn values across wake and sleep were present in children. Besides validating the prior findings that ApEn decreases from wake to sleep (including wake, rapid eye movement (REM) sleep, and non-REM sleep) in adults, we found that previously reported ApEn decreases across vigilance states in adults were also present in children (ApEn trends for both age groups: wake > REM sleep > non-REM sleep). When comparing ApEn values between age groups, adults had significantly larger ApEn values than children during wakefulness. After the application of an 8 Hz high-pass filter to the EEG signal, ApEn values were recalculated. The number of electrodes with significant vigilance state effects dropped from all 109 electrodes with the original 1 Hz filter to 1 electrode with the 8 Hz filter. The number of electrodes with significant age effects dropped from 10 to 4. Our results support the notion that ApEn can reliably distinguish between vigilance states, with low-frequency sleep-related oscillations implicated as the driver of changes between vigilance states. We suggest that the observed differences between adult and child ApEn values during wake may reflect differences in connectivity between age groups, a factor which may be important in the use of EEG to measure consciousness

    Population pharmacokinetics of fluconazole given for secondary prevention of oropharyngeal candidiasis in HIV-positive patients

    Get PDF
    Abstract.: Objectives: To determine fluconazole population pharmacokinetics and explore the relationships between fluconazole average concentration and treatment effectiveness or microbiological resistance induction during a study aimed at evaluating the efficacy, tolerability and resistance induction after secondary prevention with fluconazole (150mg weekly) versus placebo in human immunodeficiency virus-positive (HIV+) patients with oropharyngeal candidiasis. Methods: Population pharmacokinetic parameters of fluconazole determined from 458 serum drug concentration measurements obtained over 37months in 132 HIV+ patients not receiving highly active antiretroviral therapy. Mean estimates and variabilities were generated using non-linear regression analysis. Logistic and linear regression analyses were used to explore the relationships between the estimated average concentration of fluconazole and candidiasis relapse or fungal resistance towards fluconazole. Results: Fluconazole kinetics were best described by a one-compartment model with first-order oral absorption from the gastrointestinal tract. The pharmacokinetics were influenced only by body weight. No effect was observed for gender, age, height or lymphocyte CD4 counts. The mean apparent population clearance was 0.79l/h, the volume of distribution 57l and the absorption constant (ka) 0.93h-1. Inter-occasion variability in clearance (45%) was large relative to inter-subject variability (21%). Taking into account the average fluconazole concentration or the time above the minimal inhibitory concentrations did not clinically improve the prediction of the occurrence of oropharyngeal relapse or microbiological resistance. Conclusion: The relationship between fluconazole concentrations and preventive effectiveness was poor. Together with the rather large inter-occasion variability in fluconazole clearance, this suggests no role of therapeutic drug monitoring in optimising fluconazole treatment for secondary preventio

    Incidence of drug-induced liver injury in medical inpatients

    Get PDF
    Objectives: Drug-induced liver injury (DILI) is a common concern. However, data on DILI epidemiology in inpatients are sparse. Methods: To investigate the incidence of DILI, we screened all patients in the pharmacoepidemiological inpatient database according to the CIOMS (Council for International Organisation of Medical Science) criteria, which consist of the evaluation of some clinical chemistry laboratory liver parameters (CIOMS laboratory criteria) and the exclusion of any disease-related causes for the liver injury. Thus, only cases with probable or certain causality according to the World Health Organization criteria were included. Results: Among a total of 6383 patients, liver parameters were determined in 4610, and 489 among them fulfilled the CIOMS laboratory criteria. However, 401 patients had to be excluded because of disease-related liver injury and, thus, the study cohort consisted of 4209 patients at risk for DILI. Among a total of 88 DILI cases, 31 had no documented normal baseline liver parameters and, thus, represented prevalent cases. The remaining 57 represented incident DILI cases. Thus, the incidence of DILI was 1.4% (95% CI 1.0, 1.7). The drug classes most frequently causing DILI were heparins, antibacterials, tuberculostatics and antineoplastic agents. Among those, antineoplastic agents and tuberculostatics showed the highest incidence. Liver injury was not mentioned among the diagnoses or in the physician's discharge letter in about 52-68% of all cases. Conclusion: Approximately 1 in 100 patients develops DILI during hospitalisation in a department of medicine. Incidences of DILI were highest for antineoplastic agents and tuberculostatics. DILI is frequently missed and, therefore, DILI detection by diagnoses will result in misleadingly low incidence rate

    Labeling the human skeleton with 41Ca to assess changes in bone calcium metabolism

    Get PDF
    Bone research is limited by the methods available for detecting changes in bone metabolism. While dual X-ray absorptiometry is rather insensitive, biochemical markers are subject to significant intra-individual variation. In the study presented here, we evaluated the isotopic labeling of bone using 41Ca, a long-lived radiotracer, as an alternative approach. After successful labeling of the skeleton, changes in the systematics of urinary 41Ca excretion are expected to directly reflect changes in bone Ca metabolism. A minute amount of 41Ca (100nCi) was administered orally to 22 postmenopausal women. Kinetics of tracer excretion were assessed by monitoring changes in urinary 41Ca/40Ca isotope ratios up to 700days post-dosing using accelerator mass spectrometry and resonance ionization mass spectrometry. Isotopic labeling of the skeleton was evaluated by two different approaches: (i) urinary 41Ca data were fitted to an established function consisting of an exponential term and a power law term for each individual; (ii) 41Ca data were analyzed by population pharmacokinetic (NONMEM) analysis to identify a compartmental model that describes urinary 41Ca tracer kinetics. A linear three-compartment model with a central compartment and two sequential peripheral compartments was found to best fit the 41Ca data. Fits based on the use of the combined exponential/power law function describing urinary tracer excretion showed substantially higher deviations between predicted and measured values than fits based on the compartmental modeling approach. By establishing the urinary 41Ca excretion pattern using data points up to day 500 and extrapolating these curves up to day 700, it was found that the calculated 41Ca/40Ca isotope ratios in urine were significantly lower than the observed 41Ca/40Ca isotope ratios for both techniques. Compartmental analysis can overcome this limitation. By identifying relative changes in transfer rates between compartments in response to an intervention, inaccuracies in the underlying model cancel out. Changes in tracer distribution between compartments were modeled based on identified kinetic parameters. While changes in bone formation and resorption can, in principle, be assessed by monitoring urinary 41Ca excretion over the first few weeks post-dosing, assessment of an intervention effect is more reliable ∼150days post-dosing when excreted tracer originates mainly from bon

    COPILOT – Development and Implementation of International Cooperative Online Intercultural Learning

    Get PDF
    This article presents the products and evaluation results of COPILOT (Cooperative Online Peer-assisted and Intercultural Learning in Occupational Therapy), an Erasmus+ funded project undertaken by a consortium of six European universities from 2018 to 2021, which addresses the need for internationalization and intercultural learning by developing competences graduates will need in the future. Internationalization has become one of the main avenues to developing global learning in higher education. Online education has a significant role in providing opportunities for internationalization online without the high cost of travel that might deter some students. The interest in online intercultural exchange has been significantly growing in the past five years, though there is still a scarcity of fully developed models and online learning activities to facilitate the practical implementation of this kind of learning. The COPILOT project produced a theoretical framework and a practical model for facilitating online intercultural learning in occupational therapy, as well as a manual with nine innovative, accessible and flexible online learning modules, complete with practical tips on how to implement them, and a collection of online educational resources (OERs). The modules were piloted with 498 students from nine universities and then evaluated by students and teachers. The results show that the project products offer a practical opportunity to implement international and intercultural learning online for all students of occupational therapy. The need for intercultural competence within occupational therapy programs is discussed

    External Validation of the Revised Pretransplant Assessment of Mortality Score in Allogeneic Hematopoietic Cell Transplantation: A Cohort Study

    Full text link
    Pretransplant risk scores such as the revised Pretransplant Assessment of Mortality (rPAM) score help to predict outcome of patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Since the rPAM has not been validated externally in a heterogeneous patient population with different diseases, we aimed to validate the rPAM score in a real-world cohort of allo-HCT patients. A total of 429 patients were included receiving their first allo-HCT from 2008 to 2015. The predictive capacity of the rPAM score for 4-year overall survival (OS), nonrelapse mortality (NRM), and cumulative incidence of relapse (CIR) after allo-HCT was evaluated. Moreover, we evaluated the impact of the rPAM score for OS and used uni- and multivariable analyses to identify patient- and transplant-related predictors for OS. In rPAM score categories of 30, the OS probability at 4 years differed significantly with 61%, 36%, 26%, and 10%, respectively (P < 0.0001). In contrast to CIR, the NRM increased significantly in patients with higher rPAM scores (P < 0.001). Regarding the OS, the rPAM score had an area under the receiver operating characteristics curve of 0.676 (95% confidence interval [CI], 0.625-0.727) at 4 years. In the multivariable analysis, the rPAM score was associated with OS-independently of conditioning regimens (adjusted hazard ratio per 1-unit increase, 1.10; 95% CI, 1.06-1.10; P < 0.001). Additionally, forced expiratory volume in 1 second and the disease risk index were the components of the rPAM significantly associated with outcome. In our large real-world cohort with extended follow-up, the rPAM score was validated as an independent predictor of OS in patients with hematologic disorders undergoing allo-HCT
    corecore