JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
A comparison of EMG-based muscle fatigue assessments during dynamic contractions.
J Electromyogr Kinesiol
PUBLISHED: 05-22-2013
Show Abstract
Hide Abstract
Several EMG-based approaches to muscle fatigue assessment have recently been proposed in the literature. In this work, two multivariate fatigue indices developed by the authors: a generalized mapping index (GMI) and the first component of principal component analysis (PCA) were compared to three univariate indices: Dimitrovs normalized spectral moments (NSM), Gonzalez-Izals waveletbased indices (WI), and Talebinejads fractal-based Hurst Exponent (HE). Nine healthy participants completed two repetitions of fatigue tests during isometric, cyclic and random fatiguing contractions of the biceps brachii. The fatigue assessments were evaluated in terms of a modified sensitivity to variability ratio yielding the following scores (mean±std.dev.): PCA: (12.6±5.6), GMI: (11.5±5.4), NSM: (10.3±5.4), WI: (8.9±4.6), HE: (8.0±3.3). It was shown that PCA statistically outperformed WI and HE (p<0.01) and that GMI outperformed HE (p<0.02). There was no statistical difference among NSM, WI and HE (p>0.2). It was found that taking the natural logarithm of NSM and WI, although reducing the parameters sensitivity to fatigue, increased SVR scores by reducing variability.
Related JoVE Video
Characterizing the distribution and rates of microbial sulfate reduction at Middle Valley hydrothermal vents.
ISME J
PUBLISHED: 03-28-2013
Show Abstract
Hide Abstract
Few studies have directly measured sulfate reduction at hydrothermal vents, and relatively little is known about how environmental or ecological factors influence rates of sulfate reduction in vent environments. A better understanding of microbially mediated sulfate reduction in hydrothermal vent ecosystems may be achieved by integrating ecological and geochemical data with metabolic rate measurements. Here we present rates of microbially mediated sulfate reduction from three distinct hydrothermal vents in the Middle Valley vent field along the Juan de Fuca Ridge, as well as assessments of bacterial and archaeal diversity, estimates of total biomass and the abundance of functional genes related to sulfate reduction, and in situ geochemistry. Maximum rates of sulfate reduction occurred at 90?°C in all three deposits. Pyrosequencing and functional gene abundance data revealed differences in both biomass and community composition among sites, including differences in the abundance of known sulfate-reducing bacteria. The abundance of sequences for Thermodesulfovibro-like organisms and higher sulfate reduction rates at elevated temperatures suggests that Thermodesulfovibro-like organisms may have a role in sulfate reduction in warmer environments. The rates of sulfate reduction presented here suggest that--within anaerobic niches of hydrothermal deposits--heterotrophic sulfate reduction may be quite common and might contribute substantially to secondary productivity, underscoring the potential role of this process in both sulfur and carbon cycling at vents.
Related JoVE Video
Maximal rate of increase in heart rate during the rest-exercise transition tracks reductions in exercise performance when training load is increased.
J Sci Med Sport
PUBLISHED: 02-01-2013
Show Abstract
Hide Abstract
Heart rate kinetics are faster in well-trained athletes at exercise onset, indicating sensitivity to training status, but whether they track performance changes due to changes in training load is unknown.
Related JoVE Video
Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments.
Front Microbiol
PUBLISHED: 01-01-2013
Show Abstract
Hide Abstract
Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2-C5) and longer alkanes. C2-C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1-C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the ?(13)C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5‰, respectively). The concurrent depletion in the ?(13)C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (-3.5 and -6.7‰ for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1-C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3-C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial community composition and density.
Related JoVE Video
Continuous locomotion-mode identification for prosthetic legs based on neuromuscular-mechanical fusion.
IEEE Trans Biomed Eng
PUBLISHED: 07-14-2011
Show Abstract
Hide Abstract
In this study, we developed an algorithm based on neuromuscular-mechanical fusion to continuously recognize a variety of locomotion modes performed by patients with transfemoral (TF) amputations. Electromyographic (EMG) signals recorded from gluteal and residual thigh muscles and ground reaction forces/moments measured from the prosthetic pylon were used as inputs to a phase-dependent pattern classifier for continuous locomotion-mode identification. The algorithm was evaluated using data collected from five patients with TF amputations. The results showed that neuromuscular-mechanical fusion outperformed methods that used only EMG signals or mechanical information. For continuous performance of one walking mode (i.e., static state), the interface based on neuromuscular-mechanical fusion and a support vector machine (SVM) algorithm produced 99% or higher accuracy in the stance phase and 95% accuracy in the swing phase for locomotion-mode recognition. During mode transitions, the fusion-based SVM method correctly recognized all transitions with a sufficient predication time. These promising results demonstrate the potential of the continuous locomotion-mode classifier based on neuromuscular-mechanical fusion for neural control of prosthetic legs.
Related JoVE Video
EMG-based muscle fatigue assessment during dynamic contractions using principal component analysis.
J Electromyogr Kinesiol
PUBLISHED: 05-10-2011
Show Abstract
Hide Abstract
A novel approach to fatigue assessment during dynamic contractions was proposed which projected multiple surface myoelectric parameters onto the vector connecting the temporal start and end points in feature-space in order to extract the long-term trend information. The proposed end to end (ETE) projection was compared to traditional principal component analysis (PCA) as well as neural-network implementations of linear (LPCA) and non-linear PCA (NLPCA). Nine healthy participants completed two repetitions of fatigue tests during isometric, cyclic and random fatiguing contractions of the biceps brachii. The fatigue assessments were evaluated in terms of a modified sensitivity to variability ratio (SVR) and each method used a set of time-domain and frequency-domain features which maximized the SVR. It was shown that there was no statistical difference among ETE, PCA and LPCA (p>0.99) and that all three outperformed NLPCA (p<0.0022). Future work will include a broader comparison of these methods to other new and established fatigue indices.
Related JoVE Video
Abundance and diversity of archaeal ammonia oxidizers in a coastal groundwater system.
Appl. Environ. Microbiol.
PUBLISHED: 10-22-2010
Show Abstract
Hide Abstract
Nitrification, the microbially catalyzed oxidation of ammonia to nitrate, is a key process in the nitrogen cycle. Archaea have been implicated in the first part of the nitrification pathway (oxidation of ammonia to nitrite), but the ecology and physiology of these organisms remain largely unknown. This work describes two different populations of sediment-associated ammonia-oxidizing archaea (AOA) in a coastal groundwater system in Cape Cod, MA. Sequence analysis of the ammonia monooxygenase subunit A gene (amoA) shows that one population of putative AOA inhabits the upper meter of the sediment, where they may experience frequent ventilation, with tidally driven overtopping and infiltration of bay water supplying dissolved oxygen, ammonium, and perhaps organic carbon. A genetically distinct population occurs deeper in the sediment, in a mixing zone between a nitrate- and oxygen-rich freshwater zone and a reduced, ammonium-bearing saltwater wedge. Both of these AOA populations are coincident with increases in the abundance of group I crenarchaeota 16S rRNA gene copies.
Related JoVE Video
Development and validation of a measure of interpersonal strengths: The Inventory of Interpersonal Strengths.
Psychol Assess
PUBLISHED: 12-02-2009
Show Abstract
Hide Abstract
An Inventory of Interpersonal Strengths (IIS) was developed and validated in a series of large college student samples. Based on interpersonal theory and associated methods, the IIS was designed to assess positive characteristics representing the full range of interpersonal domains, including those generally thought to have negative qualities (e.g., introversion, coldness, submissiveness). The 8 subscales (octants) of the 64-item IIS demonstrated good circumplex features and reliability. Tests comparing Big 5 interpersonal factors, Inventory of Interpersonal Problems (IIP), Battery of Interpersonal Capabilities (BIC), and other interpersonal measures demonstrated convergent and discriminant validity and shared interpersonal structure. The IIS accounted for significant additional variance in life satisfaction and quality of personal relationships beyond the IIP and the BIC.
Related JoVE Video
Measurement of small birefringence and loss in a nonlinear single-mode waveguide.
Rev Sci Instrum
PUBLISHED: 06-03-2009
Show Abstract
Hide Abstract
We design and fabricate a birefringent semiconductor waveguide for application to nonlinear photonics, demonstrating that it is possible to engineer a small birefringence into such a device using multiple core layers. We also demonstrate a simple technique to accurately determine small waveguide birefringence using a differential measurement, present useful methods for coupling light into and out of the device, and make estimates of coupling and linear device losses.
Related JoVE Video
Training a multivariable myoelectric mapping function to estimate fatigue.
J Electromyogr Kinesiol
PUBLISHED: 01-15-2009
Show Abstract
Hide Abstract
The mapping index (MI) is a fatigue assessment index that uses multiple time-domain myoelectric features to train an artificial neural network (ANN) to track the progression of fatigue. This work showed that mapping functions trained using data from independent subjects and contraction conditions to yield a generalized mapping index (GMI) can assess fatigue as well as functions trained with subject and contraction-specific data to yield MI. Surface myoelectric signals were collected from nine healthy participants during isometric, cyclic and random fatiguing contractions. Two datasets were collected: one for tuning the functions and the other for testing. The performance of fatigue indices was evaluated using a newly proposed piece-wise linear signal to noise ratio. ANN based indices were compared to normalized spectral moments (NSM) and mean frequency (MF). GMI performed as well as MI and outperformed NSM and MF demonstrating that subject and contraction-specific baseline data is not needed in order to train a mapping function which can effectively assess fatigue.
Related JoVE Video
Curcumin mediated epigenetic modulation inhibits TREM-1 expression in response to lipopolysaccharide.
Int. J. Biochem. Cell Biol.
Show Abstract
Hide Abstract
Triggering receptor expressed on myeloid cells 1 (TREM-1) is a member of the immunoglobulin superfamily expressed on macrophage and neutrophils and is emerging as a potent amplifier of TLR initiated inflammatory responses. Blockade of TREM-1 improves survival in animal models of sepsis. In this study, we show that curcumin or diferuloylmethane, a yellow pigment present in turmeric, a major ingredient of curry spice inhibited the expression of TREM-1 in vitro in primary bone marrow derived macrophages and in vivo in lungs of mice with sepsis. Chromatin immunoprecipitation assay confirmed that curcumin inhibits the binding of p65 to TREM-1 promoter in response to LPS. Further we show that curcumin inhibited p300 activity in the TREM-1 promoter region leading to hypoacetylation of histone 3 and 4 in the lysine residues. Inhibition of TREM-1 by curcumin is oxidant independent. These studies are the first report to define a detailed molecular mechanism by which curcumin exerts anti-inflammatory effects through regulation of TREM-1 gene activity and provide additional mechanistic insights into the anti-inflammatory effect of curcumin.
Related JoVE Video
The IIS-32: a brief inventory of interpersonal strengths.
J Pers Assess
Show Abstract
Hide Abstract
The inventory of interpersonal strengths (IIS-64; Hatcher & Rogers, 2009 ) is a 64-item self-report measure based on the interpersonal circle (Pincus & Gurtman, 2006 ) with 8 subscales, or octants, that measure positive interpersonal characteristics covering the full range of the interpersonal circle. The IIS-64 is a valid and psychometrically robust measure of positive interpersonal features. However, because assessment time is precious in many contexts, briefer instruments might be of considerable value. We report the development of a brief version of the IIS-64 that retains the strong measurement characteristics of the original. Nonparametric item response theory methods were utilized in conjunction with factor-analytic item selection procedures in the original IIS-64 derivation sample of 1,377 to derive a 32-item version of the IIS that best represented a circumplex structure. Circumplex structure was confirmed in an additional college sample (N = 956) and in a clinical sample (N = 496). Convergence with the IIS-64 was confirmed, as were alpha and test-retest reliability. Convergent validity was demonstrated with measures of the Big Five factors. The IIS-32 should prove to be a useful and flexible measure of interpersonal strengths.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.