Step detection and activity recognition accuracy of seven physical activity monitors

The aim of this study was to compare the seven following commercially available activity monitors in terms of step count detection accuracy: Movemonitor (Mc Roberts), Up (Jawbone), One (Fitbit), ActivPAL (PAL Technologies Ltd.), Nike+ Fuelband (Nike Inc.), Tractivity (Kineteks Corp.) and Sensewear Armband Mini (Bodymedia). Sixteen healthy adults consented to take part in the study. The experimental protocol included walking along an indoor straight walkway, descending and ascending 24 steps, free outdoor walking and free indoor walking. These tasks were repeated at three self-selected walking speeds. Angular velocity signals collected at both shanks using two wireless inertial measurement units (OPAL, ADPM Inc) were used as a reference for the step count, computed using previously validated algorithms. Step detection accuracy was assessed using the mean absolute percentage error computed for each sensor. The Movemonitor and the ActivPAL were also tested within a nine-minute activity recognition protocol, during which the participants performed a set of complex tasks. Posture classifications were obtained from the two monitors and expressed as a percentage of the total task duration. The Movemonitor, One, ActivPAL, Nike+ Fuelband and Sensewear Armband Mini underestimated the number of steps in all the observed walking speeds, whereas the Tractivity significantly overestimated step count. The Movemonitor was the best performing sensor, with an error lower than 2% at all speeds and the smallest error obtained in the outdoor walking. The activity recognition protocol showed that the Movemonitor performed best in the walking recognition, but had difficulty in discriminating between standing and sitting. Results of this study can be used to inform choice of a monitor for specific applications

The <i>Pratylenchus penetrans</i> transcriptome as a source for the development of alternative control strategies:mining for putative genes involved in parasitism and evaluation of <i>in planta</i> RNAi

The root lesion nematode Pratylenchus penetrans is considered one of the most economically important species within the genus. Host range studies have shown that nearly 400 plant species can be parasitized by this species. To obtain insight into the transcriptome of this migratory plant-parasitic nematode, we used Illumina mRNA sequencing analysis of a mixed population, as well as nematode reads detected in infected soybean roots 3 and 7 days after nematode infection. Over 140 million paired end reads were obtained for this species, and de novo assembly resulted in a total of 23,715 transcripts. Homology searches showed significant hit matches to 58% of the total number of transcripts using different protein and EST databases. In general, the transcriptome of P. penetrans follows common features reported for other root lesion nematode species. We also explored the efficacy of RNAi, delivered from the host, as a strategy to control P. penetrans, by targeted knock-down of selected nematode genes. Different comparisons were performed to identify putative nematode genes with a role in parasitism, resulting in the identification of transcripts with similarities to other nematode parasitism genes. Focusing on the predicted nematode secreted proteins found in this transcriptome, we observed specific members to be up-regulated at the early time points of infection. In the present study, we observed an enrichment of predicted secreted proteins along the early time points of parasitism by this species, with a significant number being pioneer candidate genes. A representative set of genes examined using RT-PCR confirms their expression during the host infection. The expression patterns of the different candidate genes raise the possibility that they might be involved in critical steps of P. penetrans parasitism. This analysis sheds light on the transcriptional changes that accompany plant infection by P. penetrans, and will aid in identifying potential gene targets for selection and use to design effective control strategies against root lesion nematodes

Varying constants, Gravitation and Cosmology

Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. It is thus of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We thus detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, Solar system observations, meteorites dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.Comment: 145 pages, 10 figures, Review for Living Reviews in Relativit

The usefulness of pedometry in patients with chronic obstructive pulmonary disease

<p>Abstract</p> <p>Background</p> <p>Effort tolerance and daily physical activity (DPA) are predictive of quality of life and survival in COPD patients, but still remain difficult to assess based on their daily life.</p> <p>The aim of this study was: how to relate pedometry to other classic parameters commonly used in pulmonary rehabilitation (PR).</p> <p>Methods</p> <p>DPA was evaluated through pedometry. 74 patients with COPD, aged 63.55 ± 8.73 (12 stage II, FEV₁ = 60.16 ± 7.78%), (29 stage III, FEV₁ = 39.07 ± 6.30%), (33 stage IV, FEV₁ = 23.1 ± 7.18%). The monitoring was conducted for a period of 7 days before and 6 months after a pulmonary rehabilitation program (PRP) of 3 weeks. A control group consisting of 21 patients with stable COPD was evaluated initially, but they did not undergo Pulmonary Rehabilitation Program (PRP). After 6 months the patients were re-evaluated using the same parameters.</p> <p>Results and discussion</p> <p>The values are widely dispersed, with a maximum of 17,420 and minimum of 964 steps/24hrs. The average values acquired were: the lowest in COPD stage IV (2476→3112 steps/24 hrs, p < 0.0001), still with the highest increase over 6 months of PR + 636steps/24hrs; in COPD stage III the increase of DPA was + 597steps/24hrs over 6 months (5627→6224, p < 0.0001), COPD stage II registered the lowest increase + 540steps/24hrs (8724→9264, p < 0.13), probably because the subjects belonging to this stage had the best preserved DPA. The results show moderate correlation between pedometry and the 6MWT and the SGQ. (r = 0.5-0.7). However it demonstrated the positive effects of PRP, even after 6 months.</p> <p>Conclusions</p> <p>DPA decreases with increasing COPD stage, it is fluctuant with every subject, dependent on clinical status, weather and daily schedule. Wearing pedometers is very easy and motivational, provided that patients realize that they are being “watched”.</p