Search results for "dynamics"
showing 10 items of 9782 documents
An Emerging Method to Assess Tear Film Spread and Dynamics as Possible Tear Film Homeostasis Markers
2021
This study aims to assess the performance of an analysis method to measure in vivo the movement speed of tear film particles post-blink as a measure of tear film spreading. Ocular surface parameter...
Identity, Couple and Intergroup Dynamics in Intercultural Families: Implications on Life Satisfaction of Partners
2019
The current study analyzed how identity, couple, and intergroup dynamics are related to life satisfaction among 210 intercultural partners living in Italy. Three levels of analysis were considered: a micro level, taking into account the identity aspect of each partner in terms of self- or hetero-ethnic identification; a meso level, examining the passion, commitment, and intimacy of the couple sphere of the partners; a macro level investigating the discrimination that partners can perceive by the community as an effect of the relationship between dominant and minority groups. The results show that for both partners, foreign and Italian, the variables that have a predictive value on life sati…
Dynamics and molecular evolution of HIV-1 strains in Sicily among antiretroviral naïve patients.
2012
Abstract HIV-1 subtype B is the most frequent strain in Sicily. To date, there is no available data about the genetic diversity of HIV-1 viral strains circulating in Sicily among antiretroviral (ARV) naive subjects and the role of immigration as potential determinant of evolutionary dynamics of HIV-1 molecular epidemiology. For this purpose, HIV-1 polymerase (pol) sequences obtained from 155 ARV naive individuals from 2004 to 2009 were phylogenetically analysed. The overall rate of HIV-1 non-B infections was 31.0% (n = 48/155), increasing from 7.8% in 2004–2006 to 40.9% in 2009, and about one-third were identified as unique recombinant forms. CRF02_AG was the prevalent non-B clade (n = 28/4…
Flexible multibody simulation approach in the analysis of tibial strain during walking.
2007
Strains within the bone tissue play a major role in bone (re)modeling. These small strains can be assessed using experimental strain gage measurements, which are challenging and invasive. Further, the strain measurements are, in practise, limited to certain regions of superficial bones only, such as the anterior surface of the tibia. In this study, tibial strains occurring during walking were estimated using a numerical approach based on flexible multibody dynamics. In the introduced approach, a lower body musculoskeletal model was developed by employing motion capture data obtained from walking at a constant velocity. The motion capture data were used in inverse dynamics simulation to teac…
The calculation of the first positive Lyapunov exponent in sleep EEG data
1993
To help determine if the EEG is quasiperiodic or chaotic we performed a new analysis by calculating the first positive Lyapunov exponent L1 from sleep EEG data. Lyapunov exponents measure the mean exponential expansion or contraction of a flow in phase space. L1 is zero for periodic as well as quasiperiodic processes, but positive in case of chaotic processes expressing the sensitive dependence on initial conditions. We calculated L1 for sleep EEG segments of 15 healthy male subjects corresponding to sleep stages I, II, III, IV and REM (according to Rechtschaffen and Kales). Our investigations support the assumption that EEG signals are neither quasiperiodic waves nor simple noise. Moreover…
A comparison of the triceps surae and residual muscle moments at the ankle during cycling.
1991
The rigid linked system model and principles of inverse dynamics have been widely used to calculate residual muscle moments during various activities. EMG driven models and optimization algorithms have also been presented in the literature in efforts to estimate skeletal muscle forces and evaluate their possible contribution to the residual muscle moment. Additionally, skeletal muscle-tendon forces have been measured, directly, in both animals and humans. The purpose of this investigation was to calculate the moment produced by the triceps surae muscles and compare it to the residual muscle moment at the ankle during cycling at three power outputs (90, 180 and 270 W). Inferences were made r…
Quantifying Net Synergy/Redundancy of Spontaneous Variability Regulation via Predictability and Transfer Entropy Decomposition Frameworks.
2017
Objective: Indexes assessing the balance between redundancy and synergy were hypothesized to be helpful in characterizing cardiovascular control from spontaneous beat-to-beat variations of heart period (HP), systolic arterial pressure (SAP), and respiration (R). Methods: Net redundancy/synergy indexes were derived according to predictability and transfer entropy decomposition strategies via a multivariate linear regression approach. Indexes were tested in two protocols inducing modifications of the cardiovascular regulation via baroreflex loading/unloading (i.e., head-down tilt at −25° and graded head-up tilt at 15°, 30°, 45°, 60°, 75°, and 90°, respectively). The net redundancy/synergy of …
Desmopressin in the Treatment of Nocturia: A Double-Blind, Placebo-Controlled Study
2007
Objectives: To investigate efficacy, safety, and impact on quality of sleep of desmopressin in the treatment of nocturia. Methods: Adults aged >= 18 yr with nocturia (>= 2 voids/night) received desmopressin tablets (0.1, 0.2, or 0.4 mg) during a 3-wk dose-titration period. Patients should show sufficient response during the dose-titration period (>= 20% reduction in nocturnal diuresis) and a return of nocturnal diuresis to >= 80% of baseline levels during washout. Eligible patients then entered a 3-wk double-blind treatment period and received either desmopressin or placebo. Results: 127 patients were randomised to either desmopressin (n = 61) or placebo (n = 66). Twenty (33%) desmopressin-…
Plasticity of brain wave network interactions and evolution across physiologic states
2015
Neural plasticity transcends a range of spatio-temporal scales and serves as the basis of various brain activities and physiologic functions. At the microscopic level, it enables the emergence of brain waves with complex temporal dynamics. At the macroscopic level, presence and dominance of specific brain waves is associated with important brain functions. The role of neural plasticity at different levels in generating distinct brain rhythms and how brain rhythms communicate with each other across brain areas to generate physiologic states and functions remains not understood. Here we perform an empirical exploration of neural plasticity at the level of brain wave network interactions repre…
Influence of St John's wort on catecholamine turnover and cardiovascular regulation in humans
2004
BACKGROUND: St John's wort (Hypericum perforatum) is a popular over-the-counter antidepressant. Its antidepressive effect has been attributed in part to inhibition of monoamine transporters and monoamine oxidase, on the basis of in vitro studies. METHODS: In a double-blind, randomized, placebo-controlled, crossover study, 16 healthy subjects (11 men and 5 women; mean age, 31 +/- 5 years) ingested either St John's wort (300 mg three times daily) or placebo for 7 days. Imipramine treatment (50 mg three times daily) in 7 subjects served as a positive control. After treatment, physiologic and biochemical tests included cardiovascular reflex testing, graded head-up tilt testing, and plasma catec…