Search results for "variability"
showing 10 items of 904 documents
Intermittent cooling during judo training in a warm/humid environment reduces autonomic and hormonal impact
2018
Carballeira, E, Morales, J, Fukuda, DH, Granada, ML, Carratalá-Deval, V, López Díaz de Durana, A, and Stout, JR. Intermittent cooling during Judo training in a warm/humid environment reduces autonomic and hormonal impact. J Strength Cond Res 33(8): 2241-2250, 2019-The purpose of this study was to identify the effects of superficial cooling on physiological responses while training in a warm, humid environment during an international Judo training camp. Sixteen judokas (8 women and 8 men) participated in the experiment. Four high-level women and 4 men were randomly assigned to wear a cooling vest (vest group [VG]) during the recovery periods within a training session (i.e., 8 bouts of 5-minu…
Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics
2017
Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…
Single region of interest versus multislice T2* MRI approach for the quantification of hepatic iron overload.
2011
Purpose To evaluate the effectiveness of the single ROI approach for the detection of hepatic iron burden in thalassemia major (TM) patients in respect to a whole liver measurement. Materials and Methods Five transverse hepatic slices were acquired by a T2* gradient-echo sequence in 101 TM patients and 20 healthy subjects. The T2* value was calculated in a single region of interest (ROI) defined in the medium-hepatic slice. Moreover, the T2* value was extracted on each of the eight ROIs defined in the functionally independent segments. The mean hepatic T2* value was calculated. Results For patients, the mean T2* values over segments VII and VIII were significantly lower. This pattern was su…
Impact of HBV genotypes A and D genetic variability on infection evolution
2015
HBV is characterized by a high genetic variability, which is the basis of its classification into eight genotypes (A-H). HBV infection is associated with different outcomes, from self-limiting acute hepatitis to active chronic hepatitis, asymptomatic carriage, and occult infection. The aim of this study was to analyze the genetic variability of HBV genotypes A and D isolates from 79 cases of self-limiting acute hepatitis and chronic hepatitis, in order to identify HBV variants associated with resolution or chronicity of acute HBV infection. The entire preS-S sequence and a fragment of 346 bp of the preC-C region, containing Enhancer II and Basal Core Promoter sequences, were analyzed. A phy…
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 …
Spatial variability of muscle activity during human walking: The effects of different EMG normalization approaches
2015
Human leg muscles are often activated inhomogeneously, e.g. in standing. This may also occur in complex tasks like walking. Thus, bipolar surface electromyography (sEMG) may not accurately represent whole muscle activity. This study used 64-electrode high-density sEMG (HD-sEMG) to examine spatial variability of lateral gastrocnemius (LG) muscle activity during the stance phase of walking, maximal voluntary contractions (MVCs) and maximal M-waves, and determined the effects of different normalization approaches on spatial and inter-participant variability. Plantar flexion MVC, maximal electrically elicited M-waves and walking at self-selected speed were recorded in eight healthy males aged 2…
Dual-Energy CT Material Density Iodine Quantification for Distinguishing Vascular From Nonvascular Renal Lesions: Normalization Reduces Intermanufact…
2019
OBJECTIVE. The purpose of this study was to determine whether a single, uniform normalized iodine threshold reduces variability and enables reliable differentiation between vascular and nonvascular renal lesions independent of the dual-energy CT (DECT) platform used. MATERIALS AND METHODS. In this retrospective, HIPAA-compliant, institutional review board-approved study, 247 patients (156 men, 91 women; mean age ± SD, 67 ± 12 years old) with 263 renal lesions (193 nonvascular, 70 vascular) underwent unenhanced single- energy and contrast-enhanced DECT scans. One hundred and six nonvascular and 38 vascular lesions were scanned on two dual-source DECT (dsDECT) scanners, and 87 nonvascular and…
Plasma lipid profile associates with the improvement of psychological well-being in individuals with perceived stress symptoms
2020
Psychological stress is a suggested risk factor of metabolic disorders, but molecular mediators are not well understood. We investigated the association between the metabolic profiles of fasting plasma and the improvement of psychological well-being using non-targeted liquid chromatography-mass spectrometry (LC-MS) platform. The metabolic profiles of volunteers participating in the face-to-face intervention group (n = 60) in a randomised lifestyle intervention were compared to ones of controls (n = 64) between baseline and 36-week follow-up. Despite modest differences in metabolic profile between groups, we found associations between phosphatidylcholines (PCs) and several parameters indicat…
Pressure pain thresholds: Subject factors and the meaning of peak pressures.
2017
Background The assessment of pressure pain has become an integral part in pain research. The distribution of pressure under a plunger can be uneven. However, measurements based on conventional devices show the applied force or mean pressure, failing to take local pressure peaks into account. Our main question was whether peak pressures under the probe are responsible for pain onset. Methods A force-controlled algometer was fitted with a newly developed pressure-indicating film. Pressure pain thresholds (PPTs) of 100 healthy subjects (57 men, age 18-66 years) were assessed at 29 sites across the body. Each site was measured three times, nonconsecutively and presented in randomized order. For…
Categorizing the Role of Respiration in Cardiovascular and Cerebrovascular Variability Interactions
2022
Objective: Respiration disturbs cardiovascular and cerebrovascular controls but its role is not fully elucidated. Methods: Respiration can be classified as a confounder if its observation reduces the strength of the causal relationship from source to target. Respiration is a suppressor if the opposite situation holds. We prove that a confounding/suppression (C/S) test can be accomplished by evaluating the sign of net redundancy/synergy balance in the predictability framework based on multivariate autoregressive modelling. In addition, we suggest that, under the hypothesis of Gaussian processes, the C/S test can be given in the transfer entropy decomposition framework as well. Experimental p…