Search results for "stiffne"

Correlations between non ivasive renal index and markers of atherosclerosis in lupus patients

2014

Recent data suggest that renal hemodynamic parameters obtained by duplex Doppler sonography, especially the intrarenal resistive index (RI), may be associated with systemic vascular changes in some groups of patients. However, conflicting data exist about the relationship between aortic stiffness and RI in autoimmune disease, like systemic lupus erythematosus, characterized by high and early incidence of atherosclerotic disease. The aim of this study was to evaluate the relationship between RI and arterial stiffness, assessed by aortic pulse wave velocity (aPWV), and carotid atherosclerosis, evaluated by intimal medial thickness measurement (IMT) in patients with SLE. DESIGN: Cross-sectiona…

Early vascular aging in normotensive subjects with systemic lupus erythematous. Comparison with young hypertensive patients

2014

early vascular aging

RELATIONSHIP BETWEEN AORTIC PULSE WAVE VELOCITY AND RENAL RESISTIVE INDEX IN HYPERTENSIVE PATIENTS.

2013

INTRODUCTION: The assessment of renal hemodynamic parameters by duplex Doppler sonography has been used for many years as a diagnostic tool in the daily workup of kidney diseases. Recent data suggest that these parameters, especially the intrarenal resistive index (RI), may be also associated with systemic vascular changes and cardiovascular risk. However, conflicting data exist about the independent association of aortic stiffness with RI. AIM: The aim was to evaluate the relationship between RI and arterial stiffness, assessed by aortic pulse wave velocity (PWV), in the hypertensive subjects consecutively attending our hypertension centre. METHODS: We enrolled 264 subjects, aged between 3…

Dynamic force spectroscopy: analysis of reversible bond-breaking dynamics

2008

The problem of diffusive bond-dissociation in a double well potential under application of an external force is scrutinized. We compute the probability distribution of rupture forces and present a detailed discussion of the influence of finite rebinding probabilities on the dynamic force spectrum. In particular, we focus on barrier crossing upon extension, i.e. under linearly increased load, and upon relaxation starting from completely separated bonds. For large loading rates the rupture force and the rejoining force depend on the loading rate in the expected manner determined by the shape of the potential. For small loading rates the mean forces obtained from pull and relax modes approach …

An approach to evaluation of sheet bending force under successive multiaxial stress condition

2009

A new bending under tension test is presented in this paper. This method tries to evaluate bending forces in sheet under successive multiaxial stress condition. This test is carried out in only one step with a pinned cylinder over a material that has been previously deformed to pure shear condition. Due to that, the bending process is made under higher back tension forces than the ones involved in the common methods previously studied in the literature. This entails high pressure values in the sheet-bending tool contact that affects the corresponding friction process. Material is strongly strengthened as a consequence of the deformation practiced in it, and as a result of that, bending forc…

Structures of stiff macromolecules of finite chain length near the coil-globule transition: A Monte Carlo simulation

2000

Using a coarse-grained model of a semiflexible macromolecule, the equilibrium shapes of the chain have been studied varying both the temperature and the chain stiffness. We have applied Monte Carlo techniques using the bond fluctuation model for a chain length of N = 80 effective monomers, and two different types of interactions: a potential depending on the angle between successive bonds along the chain to control the chain stiffness, and an attractive interaction between non-bonded effective monomers to model variable solvent quality. In a diagram of states where chain stiffness and inverse temperature and used as variables, we find regions where the chain exists as coil, as spherical glo…

ASSOCIATION OF RENAL RESISTIVE INDEX WITH CAROTID INTIMA-MEDIA THICKNESS IN HYPERTENSIVE PATIENTS

2014

Stretch-shortening cycle: a powerful model to study normal and fatigued muscle.

2000

Stretch-shortening cycle (SSC) in human skeletal muscle gives unique possibilities to study normal and fatigued muscle function. The in vivo force measurement systems, buckle transducer technique and optic fiber technique, have revealed that, as compared to a pure concentric action, a non-fatiguing SSC exercise demonstrates considerable performance enhancement with increased force at a given shortening velocity. Characteristic to this phenomenon is very low EMG-activity in the concentric phase of the cycle, but a very pronounced contribution of the short-latency stretch-reflex component. This reflex contributes significantly to force generation during the transition (stretch-shortening) pha…

Parameters affecting the fundamental period of infilled RC frame structures

2015

Despite the fact that the fundamental period appears to be one of the most critical parameters for the seismic design of structures according to the modal superposition method, the so far available in the literature proposals for its estimation are often conflicting with each other making their use uncertain. Furthermore, the majority of these proposals do not take into account the presence of infills walls into the structure despite the fact that infill walls increase the stiffness and mass of structure leading to significant changes in the fundamental period numerical value. Toward this end, this paper presents a detailed and in-depth analytical investigation on the parameters that affect…

ASSOCIATION OF SERUM URIC ACID WITH AORTIC STIFFNESS IN UNTREATED HYPERTENSIVE SUBJECTS.

2013

INTRODUCTION: 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, that is considered the gold standard for measuring arterial stiffness. Moreover, the studies exploring the influence of SUA on aortic distensibility in subjects with arterial hypertension yielded conflicting results. AIM: The purpose of our study was to evaluate the relationships between SUA and aortic stiffness in a group of essential hypertensive patients. METHODS: We enrolled 222…