Introduction: One of the most common syndromes in Parkinson's disease (PD) is rigidity. Currently, an index is used to evaluate the level of PD by the clinical measurement of rigidity in the upper extremity. The index uses a subjective method called Unified Parkinson's Disease Rating System (UPDRS). The subjective nature of this method makes the influence of physician in the measurement of rigi...

The dependences of spreading and differentiation of stem cells plated on hydrogel and silicone gel substrates on the rigidity and porosity of the substrates have recently been a subject of some controversy. In experiments on human mesenchymal stem cells plated on soft, medium rigidity, and hard silicone gels we show that harder gels are more osteogenic, softer gels are more adipogenic, and cell...

In this work, we explore the molecular mechanisms by which local mechanical properties (e.g., rigidity) of the extracellular matrix (ECM) cooperates with soluble cues to regulate lineage commitment of human mesenchymal stem cells (hMSCs). We have established different micropost array substrates that can definitively decouple matrix rigidity from other properties including adhesiveness. We appli...

This paper defines two concepts of rigidity for tensegrity frameworks (frameworks with cables, bars, and struts): prestress stability and second-order rigidity. We demonstrate a hierarchy of rigidity--first-order rigidity implies prestress stability implies second-order rigidity implies rigiditymfor any framework. Examples show that none of these implications are reversible, even for bar framew...

Previous studies using Olson's Circumplex Model and FACES IV, the self-report assessing family functioning, did not clarify the role of rigidity, a dimension of this model. Rigidity emerged as ambiguous: it was considered either as a functional or as a dysfunctional dimension. Building upon the results of previous studies, we provided a contribution intended to disambiguate the role of rigidity...

Although a cardinal symptom of Parkinsonian disease, up to now, rigidity has been investigated much less than spasticity in hemiplegic patients. Many pathophysiological mechanisms may at least theoretically contribute to Parkinsonian rigidity, from altered viscoelastic muscle properties to inability of parkinsonian patients to relax. However, as demonstrated many years ago, motoneuron responses...

The structural rigidity property, a generalization of Laman’s theorem which characterizes rigid bar frameworks in 2D, is generally considered a good approximation of rigidity in geometric constraint satisfaction problems (GCSPs). However, it may fail even on simple GCSPs because it does not take geometric properties into account. In this paper, we question the flow-based algorithm used by Hoffm...

The structural rigidity property, a generalization of Laman’s theorem which characterizes rigid bar frameworks in 2D, is generally considered a good approximation of rigidity in geometric constraint satisfaction problems (GCSPs). However, it may fail even on simple GCSPs because it does not take geometric properties into account. In this paper, we question the flow-based algorithm used by Hoffm...

INTRODUCTION The aim was to study whether nocturnal penile rigidity (NPTR) correlates with metabolic syndrome (MetS) and testosterone in men consulting for erectile dysfunction (ED). MATERIAL AND METHODS 234 men were included in a prospective, cross-sectional pilot study. Serum total and bioavailable testosterone and other biochemical constituents were measured and compared with NPTR. Patient...

PURPOSE To evaluate possible changes of the ocular rigidity coefficient in vivo after photorefractive keratectomy (PRK) in a series of rabbit eyes, using an invasive ocular rigidity measurement device. METHODS Sixteen eyes of 8 rabbits were used in this study. One eye from each rabbit underwent PRK for -10.00 diopters (D) in a 5-mm optical zone (92 microm) while the fellow eye served as the c...