The influence of contraction type,prior performance of a maximal voluntary contraction and measurement duration on fine-wire EMG amplitude

We aimed to investigate the impact of time on fine-wire (fw) electromyography (EMG) signal amplitude, and to determine whether any attenuation is confounded by task type. Twenty healthy participants were instrumented with fw and surface (s) EMG electrodes at the biceps brachii bilaterally. Participants held a weight statically with one arm and with the other arm either repeated the same task following a maximum voluntary contraction (MVC) or repeated dynamic elbow flexion/extension contractions. Each task was repeated for 30 s every five minutes over two hours. EMG amplitude was smoothed and normalized to time = 0. Stable median power frequency of the s-EMG ruled out the confounding influence of fatigue. Repeated-measures ANCOVAs determined the effect of electrode type and time (covariate) on EMG amplitude and the confounding impact of task type. During the isometric protocol, fw-EMG amplitude reduced over time (p = 0.002), while s-EMG amplitude (p = 0.895) and MPF (p > 0.05) did not change. Fw-EMG amplitude attenuated faster during the dynamic than the isometric protocol (p = 0.008) and there was evidence that the MVC preceding the isometric protocol impacted the rate of decline (p = 0.001). We conclude that systematic signal attenuation of fw-EMG occurs over time and is more pronounced during dynamic tasks.     

Self-efficacy difference among patients with cancer with different socioeconomic status: Application of latent class analysis and standardization and decomposition analysis

IntroductionAlthough the relationship between partial socioeconomic status (SES) and self-efficacy has been studied in previous studies, few research have examined self-efficacy difference among patients with cancer with different SES.MethodsA cross-sectional survey involving 764 patients with cancer was completed. Latent class analysis (LCA) was applied to identify distinct groups of patients with cancer using four SES indicators (education, income, employment status and health insurance status). Standardization and decomposition analysis (SDA) was then used to examine differences in patients’ self-efficacy among SES groups and the components of the differences attributed to confounding factors, such as gender, age, anxiety, depression and social support.ResultsParticipants were classified into four distinctive SES groups via using LCA method, and the observed self-efficacy level significantly varied by SES groups; as theorized, higher self-efficacy was associated with higher SES. The self-efficacy differences by SES groups were decomposed into “real” group differences and factor component effects that are attributed to group differences in confounding factor compositions.ConclusionSelf-efficacy significantly varies by SES. Social support significantly confounded the observed differences in self-efficacy between different SES groups among Chinese patients with cancer.     

The ‘experimental stable’ of the BCG vaccine: safety, efficacy, proof, and standards, 1921–1933

The anti-tuberculosis BCG (Bacille Calmette-Guérin) vaccine was conceived and developed between 1905 and 1921 at Pasteur Institutes in France. Between 1921 and A. Calmette’s death in 1933, the vaccine went through a first period of national and international production and distribution for its use in humans. In France these activities were exclusively carried out by Calmette and his collaborators at the Pasteur Institute in Paris. Initially improvised production in a small room in the cellar gave way in 1931 to the construction of the spacious and magnificent ‘New laboratories for research on tuberculosis and the preparation of the BCG’ within the premises of the Pasteur Institute. Presentation and image-building of the vaccine in France insisted on the fact that the BCG was not a commercial specialty but distributed free of charge. The technical monopoly of its production nevertheless lay with the Paris Pasteur Institute and standardization of scientific proof of safety, efficacy and stability was dominated by that Institute in France. In contrast, the international production and distribution of the vaccine was entrusted and transferred, free of charge, to trustworthy laboratories outside France. Multiplication of producers and users led to an increased need for standardization. For this process the analysis distinguishes between the standardization of scientific proof concerning safety, efficacy and stability of the vaccine and standardization of its medical uses. Whereas standardization was rather successful in the inter-war period in France, the international efforts remained rather unsuccessful. Only after world war II under Scandinavian leadership and in the context of mass vaccination programs supported by the WHO and UNICEF was the international standardization effectively implemented and succeeded at least to some extend.     

Exploration of long-term growth changes using the tree-ring detrending program “Spotty”

A new tree-ring detrending program (Spotty) performs analyses of changing growth trends and environmental signals with tree age. Spotty is particularly useful in understanding the nature of long-term, centennial scale trends in tree-ring data but has a variety of dendrochronological applications. The program permits the user to define up to fifty age classes from a file of increments data. Age classes can be defined as ranges (e.g., 25–50, 100–150 years) or as single years (e.g., 25, 40, 55 years). The program will select the data corresponding to these classes and fit spline functions to the respective age class, data clouds. The user is allowed to choose a certain spline bandwidth, and can decide to fit splines to either the raw or Regional Curve Standardization (RCS) detrended data – with the RCS routine being included in Spotty – thus permitting the analysis of different underlying frequencies for each selected age class. The individual, age class splines may also be compared for common (or deviating) variance. Spotty facilitates color graphics and allows saving results for further use in other programs. PC and Mac versions of the program are available at the WSL Dendro Sciences (www.wsl.ch/forschung/forschungsunits/dendro) and LDEO Tree-Ring Lab (www.ldeo.columbia.edu/res/fac/trl/public/publicSoftware.html) web pages.