Search results for "Linear"

Effective 1-day ahead prediction of hourly surface ozone concentrations in eastern Spain using linear models and neural networks

2002

The aim of this research was to develop pure predictive models in order to provide 24 h advance forecasts of the hourly ozone concentration for the rural site of Carcagente (Valencia, Spain) and the urban sites of Paterna (Valencia, Spain) and Alcoy (Alicante, Spain) over 4 years from 1996 to 1999. The peculiarity of the model presented here is that it uses past and previously predicted information of inputs exclusively, thus being this is the first genuine 24 h advance O3 predictive model with neural networks. We used autoregressive-moving average with exogenous inputs (ARMAX), multilayer perceptrons and FIR neural networks. Five performance measures yield reasonably good results in the th…

A comparison of micropore membrane inlet mass spectrometry–derived pulmonary shunt measurement with riley shunt in a porcine model

2009

The multiple inert gas elimination technique was developed to measure shunt and the ratio of alveolar ventilation to simultaneous alveolar capillary blood flow in any part of the lung (V(A)'/Q') distributions. Micropore membrane inlet mass spectrometry (MMIMS), instead of gas chromatography, has been introduced for inert gas measurement and shunt determination in a rabbit lung model. However, agreement with a frequently used and accepted method for quantifying deficits in arterial oxygenation has not been established. We compared MMIMS-derived shunt (M-S) as a fraction of total cardiac output (CO) with Riley shunt (R-S) derived from the R-S formula in a porcine lung injury model.To allow a …

Bidirectional Glenn and antegrade pulmonary blood flow: temporary or definitive palliation?

2008

Background We sought to investigate the role of the bidirectional Glenn with antegrade pulmonary blood flow in the surgical history of children with univentricular hearts. Methods A series of 246 patients, from three joint institutions, having univentricular heart with restricted but not critical pulmonary blood flow received a bidirectional cavopulmonary shunt with additional forward pulmonary blood flow. All patients have been studied according to their progression, or not, to Fontan operation. Two hundred and eight (84.5%) patients underwent bidirectional cavopulmonary anastomosis as primary palliation. Twenty patients (8.1%) with previous pulmonary artery banding were also enrolled in t…

Blood pressure responsiveness to obstructive events during sleep after chronic CPAP

2003

The aim of this study was to investigate whether chronic continuous positive airway pressure (CPAP) affects blood pressure (BP) responsiveness to obstructive events occurring on the first night of CPAP withdrawal in obstructive sleep apnoea (OSA) after chronic treatment. Thirteen male subjects with severe OSA underwent nocturnal polysomnography with beat­by­beat BP monitoring before treatment and after 4.9±3.4 months of home CPAP (mean daily use 5.1±1.7 h). Variations in oxyhaemoglobin saturation (Δ S a,O2), systolic (Δ P s), and diastolic (Δ P d) BP within nonrapid eye movement apnoeas and hypopnoeas were measured on a sample of pre­ and post­treatment events. In addition, a pretreatment s…

Interalveolar pores increase in aging and severe airway obstruction

2021

An Improved Iterative Nonlinear Least Square Approximation Method for the Design of SISO Wideband Mobile Radio Channel Simulators

2012

In this paper, we present an improved version of the iterative nonlinear least square approximation (INLSA) method for designing measurement-based single-input single-output (SISO) wideband channel simulators. The proposed method aims to fit the time-frequency correlation function (TFCF) of the simulation model to that of a measured channel. The parameters of the simulation model are determined iteratively by minimizing the Frobenius norm, which serves as a measure for the fitting error. In contrast to the original INLSA method, the proposed approach provides a unique optimized set of model parameters, which guarantees a quasi-perfect fitting with respect to the TFCF. We analyze the perform…

UTILIZATION OF SOCIAL MEDIA AND ENTREPRENEUR KNOWLEDGE ON ENTREPRENEUR INTEREST STUDENT OF STIE PEMUDA SURABAYA

2021

This study aims to analyze the influence of the use of social media and entrepreneurial knowledge on the entrepreneurial interest of STIE Pemuda students both partially and simultaneously. This research is a descriptive quantitative research. The sample used was 100 students who had taken entrepreneurship courses. The data analysis method uses multiple linear regression analysis techniques.                     The results showed that partially the use of social media and entrepreneurial knowledge had a positive and significant effect on the entrepreneurial interest of STIE Pemuda Surabaya students. Simultaneously that the use of social media and entrepreneurial knowledge has a positive and …

Preliminary development of a questionnaire to measure the extra-pulmonary symptoms of severe asthma

2021

Abstract Background Research into the effects of asthma treatments on the extra-pulmonary symptoms of severe asthma is limited by the absence of a suitable questionnaire. The aim was to create a questionnaire suitable for intervention studies by selecting symptoms that are statistically associated with asthma pathology and therefore may improve when pathology is reduced. Methods Patients attending a specialist asthma clinic completed the 65-item General Symptom Questionnaire (GSQ-65), a questionnaire validated for assessing symptoms of people with multiple medically unexplained symptoms. Lung function (FEV1%) and cumulative oral corticosteroids (OCS) calculated from maintenance dose plus ex…

Postoperative non-invasive assessment of pulmonary vascular resistance using Doppler echocardiography.

2011

Non-invasive monitoring of pulmonary vascular resistance (PVR) in postoperative cardiac surgery patients might be useful, particularly for management of pulmonary hypertension. For this purpose, we sought to assess Doppler echocardiography in the intensive care setting. In 73 patients, hemodynamics was measured using both, invasive gold standard (pulmonary artery catheter), and non-invasively by Doppler echocardiography. Four Doppler parameters: (1) tricuspid regurgitant velocity/time-velocity-integral of right ventricular outflow tract (TRV/VTI(RVOT)), (2) tricuspid annular systolic velocity (S'), (3) tricuspid annular strain, and (4) tricuspid annular strain rate, were compared with invas…

Sub-200-kHz single soliton generation in a long ring Er-fiber laser with strict polarization control by using twisted fiber

2020

Abstract In the present work we demonstrate a novel single-soliton ultra-low pulse repetition frequency passively mode-locked erbium-doped fiber laser. We mitigate the residual linear birefringence of fiber by fiber twist to achieve a strict control of polarization. For mode-locking the nonlinear polarization rotation (NPR) was used. Special technique was applied to reduce the overdriving of NPR that allows the generation of single soliton in ultra-long cavity. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. A 192.12-kHz train of soliton pulses was obtained with pulse duration o…