Search results for "Pulse"

Assessing and accessing the small airways; implications for asthma management

2013

Despite the wealth of experience in the management of asthma, the disease remains inadequately controlled in some patients, who face long-term respiratory impairment and disability. The disease has been characterised as an inflammatory condition affecting first the larger airways and eventually the smaller airways, but there is evidence that peripheral airway involvement defines a particular and more severe phenotype of asthma. For this reason, assessing functional and biological parameters reflective of small airways involvement is important prognostically. No assessment method is universally and directly representative of peripheral airway function, but the traditional spirometric tests, …

Measuring Heart Rate with a Heat Flux Sensor

2021

Different wearable biosignal measurement applications require minimally obtrusive and highly sensitive sensors and methods of transducing the heart pulse into an electric signal. At the same time, the sensors should have minimal power consumption and preferably provide information about more than just the heart rate. In this study, a method employing a heat flux sensor for recording the pulsatile cardiac component of an arterial pulse waveform is presented. The output signals of a conventional photoplethysmography (PPG) sensor and a heat flux sensor were recorded and compared with one another. The results show that a heat flux sensor can be used for measurement of heart pulse, in addition t…

Analysis of Cardiac Pulse Arrival Time Series at Rest and during Physiological Stress

2022

The study of cardiovascular dynamics is pivotal in the prevention and monitoring of cardiovascular diseases. Pulse Arrival Time (PAT) series contain information concerning not only the dynamics of the Autonomic Nervous System (ANS), but of all the systems involved in the regulation of cardiovascular homeostasis. This study aims to highlight how indexes extracted from PAT series in time-, frequency- and information-domain allow to discriminate among different physiological conditions. Analyses were carried out on 76 young healthy subjects, at rest and during orthostatic or mental stress. Our results show that PAT indexes vary according to the ANS condition, and may thus be useful parameters …

RELATIONSHIP BETWEEN SERUM URIC ACID AND AORTIC STIFFNESS IN UNTREATED HYPERTENSIVE SUBJECTS

2013

Recent studies have reported an association between serum uric acid (SUA) and reduced arterial elasticity. However, in these studies arterial elastic properties have been assessed chiefly by measuring brachial-ankle pulse wave velocity (PWV) or peripheral PWV and only sometimes by using aortic PWV. Moreover, the relationships between SUA and arterial stiffness have never been statistically adjusted for albuminuria. Furthermore, the studies exploring the influence of uric acid on aortic distensibility in subjects with arterial hypertension yielded conflicting results. The aim of our study was to evaluate the relationships between SUA and aortic stiffness in a group of essential hypertensive …

Focal nodular hyperplasias in normal and fatty liver: a quantitative evaluation with SH U 508A and pulse inversion ultrasound

2003

Atypical liver hemangiomas: contrast enhancement patterns with SH U 508A and pulse inversion ultrasound

2003

SYSTEMIC ARTERIAL CHANGES AND PULSE PRESSURE: DIFFERENT IMPACT ON RENAL HAEMODYNAMICS IN HYPERTENSIVE PATIENTS.

2015

Objective: Renal resistance index (RRI) is used for kidney disease detection and prognosis, but it also appears a good indicator of systemic vascular changes in hypertensive subjects. Structural atherosclerotic damage, arterial stiffness and pulse pressure may interact each other, and the relationship between intrarenal haemodynamics and systemic vascular alterations has been widely investigated. However, the independent impact of all these parameters on renal haemodynamics and the mechanisms by which they affect renal vasculature remain to be clarified. Design and method: We enrolled 463 hypertensive patients (30–70 years) with normal renal function (group 0; n = 280) and with chronic kidn…

A powerful thyristor modulator for a microtron

1980

Abstract The circuit of a powerful modulator is illustrated and a detailed description is given of the modulator construction and in particular of the components employed. The main parameters are: length of shaped pulse 2 μs; amplitude of the output voltage 30 kV; pulse repetition frequency 50–200 Hz. The compactness of this device, its comparatively low cost and its good performance, as illustrated in the attached photographs, make it suitable for use in accelerator engineering (microtron).

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…

Assessment of a Modified Acoustic Lens for Electromagnetic Shock Wave Lithotripters in a Swine Model

2013

The acoustic lens of the Modularis electromagnetic shock wave lithotripter (Siemens, Malvern, Pennsylvania) was modified to produce a pressure waveform and focal zone more closely resembling that of the original HM3 device (Dornier Medtech, Wessling, Germany). We assessed the newly designed acoustic lens in vivo in an animal model.Stone fragmentation and tissue injury produced by the original and modified lenses of the Modularis lithotripter were evaluated in a swine model under equivalent acoustic pulse energy (about 45 mJ) at 1 Hz pulse repetition frequency. Stone fragmentation was determined by the weight percent of stone fragments less than 2 mm. To assess tissue injury, shock wave trea…