Search results for "Principal Component Analysis"

Performance‐determining factors in biathlon prone shooting without physical stress

2021

This study investigated the most important factors determining biathlon prone shooting performance. 10 female and 16 male biathletes (age 19.9 ± 2.9 years) from the national teams of Finland and Vuokatti-Ruka Sports Academy performed 65 biathlon prone shooting shots without physical stress under laboratory conditions. Shooting performance and multiple aiming point trajectory variables were measured together with an analysis of triggering force. Based on the aiming point trajectory data principal component analysis, we identified four technical components in biathlon prone shooting: stability of hold, aiming accuracy, cleanness of triggering and timing of triggering. Multiple regression anal…

Tri-dimensional and triphasic muscle organization of whole-body pointing movements.

2010

Previous kinematic and kinetic studies revealed that, when accomplishing a whole-body pointing task beyond arm's length, a modular and flexible organization could represent a robust solution to control simultaneously target pointing and equilibrium maintenance. Here, we investigated the underlying mechanisms that produce such a coordinative kinematic structure. We monitored the activity of a large number of muscles spread throughout subjects' bodies while they performed pointing movements beyond arm's length, either with or without imposition of postural or pointing constraints. Analyses revealed that muscle signals lied on a tri-dimensional hyper-plane and were temporally organized accordi…

Updating semen analysis: a subpopulation approach

2019

Modular Control of Pointing beyond Arm's Length

2009

Hand reaching and bipedal equilibrium are two important functions of the human motor behavior. However, how the brain plans goal-oriented actions combining target reaching with equilibrium regulation is not yet clearly understood. An important question is whether postural control and reaching are integrated in one single module or controlled separately. Here, we show that postural control and reaching motor commands are processed by means of a modular and flexible organization. Principal component and correlation analyses between pairs of angles were used to extract global and local coupling during a whole-body pointing beyond arm's length. A low-dimensional organization of the redundant ki…

Metabolite profiling of fecal water extracts from human colorectal cancer.

2009

Colorectal cancer is the second leading cause of cancer death in developed countries. There is a need for better preventive strategies to improve the outcome of this disease. The increasing availability of high-throughput methodologies opens up new possibilities for screening new markers. The application of NMR metabolic profiling to fecal water extracts has interesting potential as a diagnostic tool for detecting colorectal cancer. We obtained NMR metabolic profiles of fecal water extracts from patients with colorectal cancer and healthy individuals, to characterize possible differences between them and to identify potential diagnostic markers. Our results show that metabolic profiling of …

Changes in power curve shapes as an indicator of fatigue during dynamic contractions.

2010

The purpose of this study was to analyze exercise-induced leg fatigue during a dynamic fatiguing task by examining the shapes of power vs. time curves through the combined use of several statistical methods: B-spline smoothing, functional principal components and (supervised and unsupervised) classification. In addition, granulometric size distributions were also computed to allow for comparison of curves coming from different subjects. Twelve physically active men participated in one acute heavy-resistance exercise protocol which consisted of five sets of 10 repetition maximum leg press with 120 s of rest between sets. To obtain a smooth and accurate representation of the data, a basis of …

Development of a questionnaire measuring treatment concerns in regular dental patients

2008

–  Objectives:  The aim of this study was to develop an instrument measuring core concerns about dental treatment guided by Reiss’ expectancy theory of fear. This would include the content domains of injury, somatic reaction and interpersonal concerns, to study the underlying factorial structure, and to determine the test quality of the resulting subscales. Methods:  A total of 555 regular dental patients answered the item pool. Subsamples filled in the Dental Anxiety Scale (DAS) (n = 346) and the Anxiety-Present Scale of the state-form of the State-Trait Anxiety Inventory (STAI-S) (n = 187). A second sample (n = 89) was used to determine test-retest reliability and bias for social desirabi…

Muscular synergies during motor corrections: investigation of the latencies of muscle activities.

2010

To reduce the complexity of muscular control, a small number of muscular activations are combined to produce an infinity of movements. This concept of muscle synergies has been widely investigated, mainly by means of principal component analyses (PCA) in the case of unperturbed movements. However, reaching movements can be altered at any time if the target location is changed during their execution. In this case, PCA does not precisely measure the latencies of muscles activities. We develop here a simple method to investigate how a random target jump toward a single location induced motor corrections in the whole musculature by precisely determining the latencies of muscle activities during…

Population-based validation of a German version of the Brief Resilience Scale.

2017

Smith and colleagues developed the Brief Resilience Scale (BRS) to assess the individual ability to recover from stress despite significant adversity. This study aimed to validate the German version of the BRS. We used data from a population-based (sample 1: n = 1.481) and a representative (sample 2: n = 1.128) sample of participants from the German general population (age ≥ 18) to assess reliability and validity. Confirmatory factor analyses (CFA) were conducted to compare one- and two-factorial models from previous studies with a method-factor model which especially accounts for the wording of the items. Reliability was analyzed. Convergent validity was measured by correlating BRS scores …

Dimension reduction: additional benefit of an optimal filter for independent component analysis to extract event-related potentials.

2011

The present study addresses benefits of a linear optimal filter (OF) for independent component analysis (ICA) in extracting brain event-related potentials (ERPs). A filter such as the digital filter is usually considered as a denoising tool. Actually, in filtering ERP recordings by an OF, the ERP' topography should not be changed by the filter, and the output should also be able to be modeled by the linear transformation. Moreover, an OF designed for a specific ERP source or component may remove noise, as well as reduce the overlap of sources and even reject some non-targeted sources in the ERP recordings. The OF can thus accomplish both the denoising and dimension reduction (reducing the n…