127 research outputs found

    Bounded Protocols for Efficient Reliable Message Transmission

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    In the reliable message transmission problem (RMTP) processors communicate by exchanging messages, but the channel that connects two processors is subject to message loss, duplication, and reordering. Previous work focused on proposing protocols in asynchronous systems, where message size is finite and sequence numbers are bounded. However, if the channel can duplicate messages, lose messages, and arbitrarily reorder the messages, the problem is unsolvable. In this thesis, we consider a strengthening of the asynchronous model in which reordering of messages is bounded. In this model, we develop two efficient protocols to solve the RMTP: (1) when messages may be duplicated but not lost and (2) when messages may be duplicated and lost. This result is in contrast to the impossibility of such an algorithm when reordering is unbounded. Our protocols have the pleasing property that no messages need to be sent from the receiver to the sender

    Body Composition Assessment in Mexican Children and Adolescents. Part 1: Comparisons between Skinfold-Thickness, Dual X-ray Absorptiometry, Air-Displacement Plethysmography, Deuterium Oxide Dilution, and Magnetic Resonance Imaging with the 4-C Model

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    The evaluation of body composition (BC) is relevant in the evaluation of children's health-disease states. Different methods and devices are used to estimate BC. The availability of methods and the clinical condition of the patient usually defines the ideal approach to be used. In this cross-sectional study, we evaluate the accuracy of different methods to estimate BC in Mexican children and adolescents, using the 4-C model as the reference. In a sample of 288 Mexican children and adolescents, 4-C body composition assessment, skinfold-thickness (SF), dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), and deuterium dilution (D2O) were performed, along with MRI in a subsample (52 participants). The analysis of validity was performed by correlation analysis, linear regression, and the Bland-Altman method. All methods analyzed showed strong correlations for FM with 4-C values and between each other; however, DXA and MRI overestimated FM, whereas skinfolds and ADP under-estimated FM. Conclusion: The clinical assessment of BC by means of SF, ADP, DXA, MRI and D2O correlated well with the 4-C model and between them, providing evidence of their clinical validity and utility. The results from different methods are not interchangeable. Preference between methods may depend on their availability and the specific clinical setting

    Factores psicológicos asociados con el rendimiento escolar en estudiantes de educación básica

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    El rendimiento escolar se ha explicado desde factores cognitivos y pedagógicos, aunque de modo insuficiente desde estos últimos. Se plantea determinar la relación entre resiliencia, autoestima y autoeficacia con rendimiento escolar mediante la aplicación de tres instrumentos: cuestionario de resiliencia, autoestima y escala de autoeficacia escolar, y rendimiento escolar mediante el promedio de calificaciones. En el estudio, se tomó una El rendimiento escolar se ha explicado desde factores cognitivos y pedagógicos, aunque de modo insuficiente desde estos últimos. Se plantea determinar la relación entre resiliencia, autoestima y autoeficacia con rendimiento escolar mediante la aplicación de tres instrumentos: cuestionario de resiliencia, autoestima y escala de autoeficacia escolar, y rendimiento escolar mediante el promedio de calificaciones. En el estudio, se tomó una muestra de 414 alumnos, entre 8 y 13 años (m = 9.9, ds = .94), de escuelas públicas y privadas de la ciudad de Toluca, México. Se identificaron relaciones positivas y significativas entre las variables para con el rendimiento escolar, así como diferencias respecto del tipo de escuela sólo en autoestima. Se sugiere continuar con el análisis del rendimiento escolar con la finalidad de construir modelos explicativos sobre la interacción de estas variables

    HPLC-PDA METHOD FOR THE QUANTIFICATION OF PARACETAMOL IN PLASMA: APPLICATION TO PK/PD STUDIES WITH ARTHRITIC RATS

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    Objective: To develop and validate an easy, rapid, sensitive and selective high-performance liquid chromatography with photodiode diode-array (HPLC-PDA) detection method for quantification of paracetamol and to demonstrate its application in a pharmacokinetic–pharmacodynamic study with arthritic rats.Methods: Paracetamol was separated from plasma samples (50-100 µl) by a single protein precipitation step, prior to HPLC-PDA detection. The separation was performed on a Knauer Eurospher II, C18 column 5 µm, 150 × 4.6 mm. The mobile phase comprised a mixture of water: methanol (75:25) and the flow rate was 1.1 ml/min. The detection wavelength was set at 245 nm. All analyses were carried out at room temperature (25 °C). Pharmacodynamics data were obtained with a gout-type pain model in rats.Results: The method was linear within a range of 0.2-200 µg/ml (R2≥0.99). The intra-day and inter-day precision and accuracy expressed as coefficient of variation and relative error, respectively were below 10%. The lower limit of quantification was 0.2 µg/ml. Plasma samples were stable at least for 5 w at ‒20° C.Conclusion: The validated method is sensitive, precise, accurate and specific as other more complex high-performance liquid chromatographic methods coupled to mass spectrometry (HPLC-MS), using small plasma samples (50-100 µl) and with a short time analysis (<5 min). The method was successfully applied to a pharmacokinetic-pharmacodynamic study of paracetamol in arthritic rats.Â

    CT fluoroscopy‐guided pancreas transplant biopsies: a retrospective evaluation of predictors of complications and success rates

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    To identify predictors of biopsy success and complications in CT-guided pancreas transplant (PTX) core biopsy. We retrospectively identified all CT fluoroscopy-guided PTX biopsies performed at our institution (2000-2017) and included 187 biopsies in 99 patients. Potential predictors related to patient characteristics (age, gender, body mass index (BMI), PTX age, PTX volume) and procedure characteristics (biopsy depth, needle size, access path, number of samples, interventionalist's experience) were correlated with biopsy success (sufficient tissue for histologic diagnosis) and the occurrence of complications. Biopsy success (72.2%) was more likely to be obtained in men [+25.3% (10.9, 39.7)] and when the intervention was performed by an experienced interventionalist [+27.2% (8.1, 46.2)]. Complications (5.9%) occurred more frequently in patients with higher PTX age [OR: 1.014 (1.002, 1.026)] and when many (3-4) tissue samples were obtained [+8.7% (-2.3, 19.7)]. Multivariable regression analysis confirmed male gender [OR: 3.741 (1.736, 8.059)] and high experience [OR: 2.923 (1.255, 6.808)] (biopsy success) as well as older PTX age [OR: 1.019 (1.002, 1.035)] and obtaining many samples [OR: 4.880 (1.240, 19.203)] (complications) as independent predictors. Our results suggest that CT-guided PTX biopsy should be performed by an experienced interventionalist to achieve higher success rates, and not more than two tissue samples should be obtained to reduce complications. Caution is in order in patients with older transplants because of higher complication rates

    Mediterranean dietary patterns related to sleep duration and sleep-related problems among adolescents: The EHDLA study

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    Purpose: The aim of the present study was to examine the association of adherence to the Mediterranean Diet (MD) and its specific components with both sleep duration and sleep-related disorders in a sample of adolescents from the Valle de Ricote (Region of Murcia, Spain). Methods: This cross-sectional study included a sample of 847 Spanish adolescents (55.3% girls) aged 12–17 years. Adherence to the MD was assessed by the Mediterranean Diet Quality Index for Children and Teenagers. Sleep duration was reported by adolescents for weekdays and weekend days separately. The BEARS (Bedtime problems, Excessive daytime sleepiness, Awakenings during the night, Regularity and duration of sleep, and Sleep-disordered breathing) screening was used to evaluate issues related to sleep, which include difficulties at bedtime, excessive drowsiness during the day, waking up frequently during the night, irregularity, length of sleep, and breathing issues while sleeping. Results: Adolescents who presented a high adherence to the MD were more likely to meet the sleep recommendations (OR = 1.52, 95% CI 1.12–2.06, p = 0.008) and less likely to report at least one sleep-related problem (OR = 0.56, 95% CI 0.43–0.72, p < 0.001). These findings remained significant after adjusting for sex, age, socioeconomic status, waist circumference, energy intake, physical activity, and sedentary behavior, indicating a significant association of adherence to the MD with sleep outcomes (meeting sleep recommendations: OR = 1.40, 95% CI 1.00–1.96, p = 0.050; sleep-related problems: OR = 0.68, 95% CI 0.50–0.92, p = 0.012). Conclusions: Adolescents with high adherence to the MD were more likely to report optimal sleep duration and fewer sleep-related problems. This association was more clearly observed for specific MD components, such as fruits, pulses, fish, having breakfast, dairies, sweets, and baked goods/pastries

    Clinical effect of obesity on N-terminal pro-B-type natriuretic peptide cut-off concentrations for the diagnosis of acute heart failure

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    AIMS Obese patients have lower natriuretic peptide concentrations. We hypothesized that adjusting the concentration of N-terminal pro-B-type natriuretic peptide (NT-proBNP) for obesity could further increase its clinical utility in the early diagnosis of acute heart failure (AHF). METHODS AND RESULTS This hypothesis was tested in a prospective diagnostic study enrolling unselected patients presenting to the emergency department with acute dyspnoea. Two independent cardiologists/internists centrally adjudicated the final diagnosis using all individual patient information including cardiac imaging. NT-proBNP plasma concentrations were applied: first, using currently recommended cut-offs; second, using cut-offs lowered by 33% with body mass index (BMI) of 30-34.9 kg/m2^{2} and by 50% with BMI ≥ 35 kg/m2^{2} . Among 2038 patients, 509 (25%) were obese, of which 271 (53%) had AHF. The diagnostic accuracy of NT-proBNP as quantified by the area under the receiver-operating characteristic curve was lower in obese versus non-obese patients (0.890 vs. 0.938). For rapid AHF rule-out in obese patients, the currently recommended cut-off of 300 pg/ml achieved a sensitivity of 96.7% (95% confidence interval [CI] 93.8-98.2%), ruling out 29% of patients and missing 9 AHF patients. For rapid AHF rule-in, the age-dependent cut-off concentrations (age 75 years: 1800 pg/ml) achieved a specificity of 84.9% (95% CI 79.8-88.9%). Proportionally lowering the currently recommended cut-offs by BMI increased sensitivity to 98.2% (95% CI 95.8-99.2%), missing 5 AHF patients; reduced the proportion of AHF patients remaining in the 'gray zone' (48% vs. 26%; p = 0.002), achieving a specificity of 76.5% (95% CI 70.7-81.4%). CONCLUSIONS Adjusting NT-proBNP concentrations for obesity seems to further increase its clinical utility in the early diagnosis of AHF

    Lower diagnostic accuracy of hs-cTnI in patients with prior coronary artery bypass grafting

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    High-sensitivity cardiac troponin T (hs-cTnT) and the ESC 0/1h-hs-cTnT-algorithm have worse performance in the early diagnosis of myocardial infarction (MI) in patients with prior coronary artery bypass grafting (CABG). It is unknown, whether this concern applies also to hs-cTnI, the most widely used analyte worldwide.; In an international multicenter diagnostic study, two cardiologists centrally adjudicated the final diagnosis in patients presenting to the emergency department with symptoms suggestive of MI according to the Third Universal Definition of MI. The objective was to compare the diagnostic accuracy of hs-cTnI assays and their performance within the ESC hs-cTnI 0/1h-algorithms in patients with versus without prior CABG. Findings were externally validated in an U.S. multicenter diagnostic study.; A total of 392/5'200 patients (8%) had prior coronary artery bypass grafting (CABG). Diagnostic accuracy of hs-cTnI as quantified by the area under the receiver-operating characteristics-curve (AUC) in these patients was high, but lower versus patients without prior CABG (e.g. hs-cTnI-Architect 0.91 versus 0.95; p = 0.016). Sensitivity/specificity of rule-out/in by the European Society of Cardiology (ESC) 0/1h-hs-cTnI-algorithms remained very high [e.g. hs-cTnI-Architect 100% and 93.5%], but efficacy was lower (52% versus 74%, p < 0.01). External validation (n = 2113) confirmed these findings in 192 patients with prior CABG using hs-cTnI-Atellica, with 52% versus 36% (p < 0.001) remaining in the observe zone.; Diagnostic accuracy of hs-cTnI and efficacy of the ESC 0/1h-hs-cTnI-algorithms are lower in patients with prior CABG, but sensitivity/specificity remain very high.; https://clinicaltrials.gov/ct2/show/NCT00470587, number NCT00470587
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