Mechanics of magnetic robots akin to soft beams supported at unanchored contacts

This article presents a novel algorithm to predict the shape and the support configurations of a magnetic robot acting like a supple beam which deforms due to an imposed magnetic field. The soft magnet loosely rests on a flat horizontal surface which provides the pivoting supports to the robot to attain its deformed shape. The key difficulty in analysis of the mechanics is the lack of any prior knowledge about the location of the contacts where the distorted beam finds support from the ground. This paper outlines an algorithm in which different possibilities referred to as modes are checked systematically to locate the placement and the nature of such supports. Consequently, the 2D shape of the soft beam can be determined without any heuristic assumption about where the magnetic robot is touching the solid surface. This work focuses on single contact sections although the algorithm idea is valid for multiple contacts as well. The mathematical theory and the numerical scheme are validated by comparing the simulated results with existing experimentally obtained configurations. Also, the parametric space of system-defining non-dimensional parameters is explored to determine when a transition happens from one mode to another, and which magnetization methods are desirable for higher stability. Through theoretical simulation the results show that a thin rectangular cross-section provides higher deformation when compared to the other two tested shapes (circular and equilateral triangle cross-section).

MSA, The French Agricultural Social Protection scheme

As the second largest social protection scheme in France, the Agricultural Social Mutuality (fr. Mutualité sociale agricole, MSA) is responsible for providing all compulsory social security coverage for the entire agricultural population and its beneficiaries, whether it concerns health, family, retirement, work-related accidents or occupational diseases. The MSA is responsible for collecting social security premiums and contributions, but also unemployment insurance and conventional contributions for many organizations1. It differs from other French social security schemes in that it provides a one-stop shop for individuals and companies to deal with a single contact person for all matters relating to their social protection throughout their lives. In addition to its basic mission, it carries out a policy of health and social action adapted to its population and is also in charge of occupational medicine and the prevention of professional risks in the agricultural sector. It can support all actions aiming to promote the coordination and the offer of care in rural areas2. As a mutualistic organization, the MSA is the expression of a responsible and supportive democracy at the service and in proximity of the rural world. The representativeness of its elected delegates, its knowledge of the territories and their stakeholders, and its role as a professional agricultural organization give it an indispensable expertise that allows it to work for the cohesion of the territories while guaranteeing access to quality public services. This expertise also enables it to be present abroad as part of formalized exchanges in European networks and international cooperation projects.

Multiscale study of the dynamic friction coefficient due to asperity plowing

A macroscopically nominal flat surface is rough at the nanoscale level and consists of nanoasperities. Therefore, the frictional properties of the macroscale-level rough surface are determined by the mechanical behaviors of nanoasperity contact pairs under shear. In this work, we first used molecular dynamics simulations to study the non-adhesive shear between single contact pairs. Subsequently, to estimate the friction coefficient of rough surfaces, we implemented the frictional behavior of a single contact pair into a Greenwood-Williamson-type statistical model. By employing the present multiscale approach, we used the size, rate, and orientation effects, which originated from nanoscale dislocation plasticity, to determine the dependence of the macroscale friction coefficient on system parameters, such as the surface roughness, separation, loading velocity, and direction. Our model predicts an unconventional dependence of the friction coefficient on the normal contact load, which has been observed in nanoscale frictional tests. Therefore, this model represents one step toward understanding some of the relevant macroscopic phenomena of surface friction at the nanoscale level.

Evaluation of Sampling Methods for Detection of Pathogens from Steel Surfaces; Contact Plates, Foam Swabs, and Flocked Swabs

Background: Contaminated healthcare surfaces can serve as reservoirs for the transmission of pathogens. Sensitive sampling methods are needed to investigate sources of pathogens for implementing effective disinfection strategies and thereby preventing environmental transmission. Conventional approaches employ swabs to sample environmental surfaces. Contact plates represent an alternative approach for sampling healthcare surfaces that does not require lab processing, though little is known about their performance. A contact plate is an agar plate that is overfilled with selective or nonselective media. It can be gently applied to the surface, then simply incubated at a temperature optimal for target organism (s), thus saving time and resources. Methods: In this study, contact plates containing trypticase soy agar with 5% sheep blood (TSAII), foam swabs, and flocked swabs were evaluated for their ability to recover 4 pathogens that persist on healthcare surfaces. Stainless-steel coupons (4 in2) were inoculated with the following pathogens (102 CFU): Acinetobacter baumannii (AB, strain type 12), carbapenemase-producing KPC+ Klebsiella pneumoniae (KP; ATCC BAA-1705); methicillin-resistant Staphylococcus aureus (MRSA; ATCC 43300); and vancomycin-resistant Enterococcus faecalis (VRE; Van A + 256). The plates were allowed to dry 1 hour. Sampling with CPs was performed in 2 ways; (1) a single contact plate was used to sample 1 stainless-steel surface and (2) a composite was collected by 3 sequential contact-plate samplings of the same stainless-steel surface. The contact plates were then incubated at 351C. Foam and flocked swabs were premoistened with phosphate-buffered saline + 0.02% polysorbate 80 (PBST) and were used to sample the stainless-steel coupons. Swabs were held for 1 hour and processed by sonication and vortexing in 5 mL of PBST, then the eluent was cultured and CFU counted. Mean percentage recoveries (%R) relative to the inoculum were calculated and compared. Results: When the %R for all 4 pathogens were pooled, the composite contact-plate sampling method yielded the highest, (P < .05) (66.0%; SD, 0.22), followed by the single contact plate method (39.7%; SD, 0.12), foam swab (32.9%; SD, 0.18), and flocked swab (20.3%; SD, 0.20). The composite contact plate method yielded the highest %R for VRE (102.1 %; SD, 0.17), and the lowest %R was observed when using flocked swabs to recover KP (6.3%; SD, 0.05). Conclusions: The contact-plate composite method may provide investigators with minimal environmental microbiology capacity an alternative method for environmental sampling and detection of organisms from surface areas (4 in 2) with low bioburden.Funding: NoneDisclosures: None

[D-Leu1]MC-LR Has Lower PP1 Inhibitory Capability and Greater Toxic Potency than MC-LR in Animal and Plant Tissues

Two microcystins, MC-LR and [D-Leu1]MC-LR, present in La Plata Basin blooms, are differentiated by substitution of D-Alanine for D-Leucine at position 1. Our objective was to evaluate acute toxicity of [D-Leu1]MC-LR and MC-LR in mice (N:NIH Swiss) and beans (Phaseolus vulgaris). We observed variations in [D-Leu1]MC-LR lethal doses with respect to those reported for MC-LR (100 μg/kg), with an increased liver/body weight ratio and intrahepatic hemorrhages in mice exposed to 50–200 μg [D-Leu1]MC-LR/kg and slight steatosis after a single 25 μg [D-Leu1]MC-LR/kg i.p. dose. Our study in the plant model showed alterations in germination, development, morphology and TBARs levels after a single contact with the toxins during imbibition (3.5 and 15 µg/mL), those treated with [D-Leu1]MC-LR being more affected than those treated with the same concentration of MC-LR. Protein phosphatase 1 (PP1) IC50 values were 40.6 nM and 5.3 nM for [D-Leu1]MC-LR and MC-LR, respectively. However, the total phosphatase activity test in root homogenate showed 60% inhibition for [D-Leu1]MC-LR and 12% for MC-LR. In mouse liver homogenate, 50% inhibition was observed for [D-Leu1]MC-LR and 40% for MC-LR. Our findings indicate the need for further research into [D-Leu1]MC-LR toxicity since together with oxidative stress, the possible inhibition of other phosphatases could explain the differences detected in the potency of the two toxins.

[D-Leu1]MC-LR and MC-LR: A Small–Large Difference: Significantly Different Effects on Phaseolus vulgaris L. (Fabaceae) Growth and Phototropic Response after Single Contact during Imbibition with Each of These Microcystin Variants

[D-Leu1]MC-LR and MC-LR, two microcystins differing in one amino acid, constitute a sanitary and environmental problem owing to their frequent and concomitant presence in water bodies of the Americas and their association with human intoxication during recreational exposure to cyanobacterial bloom. Present in reservoirs used for irrigation as well, they can generate problems in the development of crops such as Phaseolus vulgaris, of nutritional and economic interest to the region. Although numerous works address the toxic effects of MC-LR, information on the toxicity of [D-Leu1]MC-LR is limited. Our objective was to study the toxic effects of [D-Leu1]MC-LR and MC-LR (3.5 µg/ml) on P. vulgaris after a single contact at the imbibition stage. Our findings indicate that 10 days post treatment, [D-Leu1]MC-LR generates morphological and physiological alterations more pronounced than those caused by MC-LR. In addition to the alterations produced by [D-Leu1]MC-LR in the development of seedlings and the structure of the leaves, roots and stems, we also found alterations in leaf stomatal density and conductivity, a longer delay in the phototropic response and a decrease in the maximum curvature angles achieved with respect to that observed for MC-LR. Our findings indicate that these alterations are linked to the greater inhibition of phosphatase activity generated by [D-Leu1]MC-LR, rather than to oxidative damage. We observed that 30 days after treatment with MC-LR, plants presented better development and recovery than those treated with [D-Leu1]MC-LR. Further studies are required on [D-Leu1]MC-LR and MC-LR toxicity and their underlying mechanisms of action.

Decomposition and modeling of signal shapes of single point cardiac monitoring

We introduce a novel method for electronic recording of cardiac signals from a single point at the skin in contrast to classical differential electrocardiography (ECG). Ultralownoise transistor devices with an adaptable, auto-stabilizing transimpedance amplifier are able to measure tiny skin potential modulations from a single contact electrode located at an individual’s wrist (single-point cardiography-SPC). Although SPC signals were highly prone to interspersed noise, they contained periodic patterns. In an electromagnetically shielded setting, we could clearly extract breathing and cardiac rhythms from the acquired SPC signals. As the reference, we measured ECG in parallel. Several signal-processing techniques like smoothening, correlation, decomposition and signal extraction showed that SPC signals contain breathing and periodic heart potential variations, which are time-correlated with ECG. In the future, we intent to use this novel technique to measure heart signals from patients in different health conditions.

Geriatrische revalidatiezorg na triage op de Spoedeisende Hulp: Patiëntkarakteristieken en revalidatie-uitkomsten

In the Netherlands geriatric rehabilitation is possible (among others) for patients who are selected by a geriatrician at the emergency department of a hospital. The aim of this study was to investigate the rehabilitation trajectory of patients who were selected for geriatric rehabilitation at the emergency department after a single contact with the geriatrician and to identify patient factors related to rehabilitation outcome. Successful rehabilitation was defined as discharge to home or a residential care facility after a maximum of 6 months. All patients who in 2016 were selected for geriatric rehabilitation were included. Data were collected retrospectively from electronic patient files. 74 patients were included (mean age 84.7 years). 84% were successfully discharged home or to a residential care facility within six months. The presentation with a fall and the absence of a partner at home was higher in the unsuccessful group. In the successful group more patients lived independent and without professional help prior to rehabilitation. Noteworthy is that the analysed patient group is a frail group, considering the high one-year mortality (21,6%) and overall functional decline despite geriatric rehabilitation.