Studying the creep behaviour of strechable capacitive sensor with barium titanate silicone elastomer composite

In this paper, the creep behaviour of stretchable interdigital capacitive (IDC) large strain sensors is studied. A generalized Kelvin-Voigt (GKV) model is used to study the creep behaviour of the sensor's substrate material, manufactured from silicone elastomer (Ecoflex 00−30) with barium titanate (BTO) filler. Creep experiments are performed on sensors with 10, 20, 30 and 40 wt% BTO nanoparticles with dimensions of 100 nm and 200 nm dispersed in the elastomer. The BTO was used to increase the overall permittivity of the substrate, hence raising the capacitance of the IDC sensor. The effect of BTO on the GKV model parameters was studied in detail through analysis of the creep response. The pristine Ecoflex silicone elastomer is predominately a hyperelastic material, which shows negligible creep, while the addition of BTO particles led to the composite exhibiting creep such that the composite behaves like a visco-hyperelastic material. Hence, this behaviour results in the creep affecting the electrical sensing performance of the capacitive strain sensors during static loading conditions. This information provides insights on the impact of composite composition on creep-resistance and output signal of the sensor (capacitance).</p

The effect of barium titanate ceramic loading on the stress relaxation behavior of barium titanate-silicone elastomer composites

The stress relaxation behavior of barium titanate (BTO)-elastomer (Ecoflex) composites, as used in large strain sensors, is studied using the generalized Maxwell-Wiechert model. In this article, we examine the stress relaxation behavior of ceramic polymer composites by conducting stress relaxation tests on samples prepared with varying the particle loading by 0, 10, 20, 30, and 40 wt% of 100 and 200 nm BTO ceramic particles embedded in a Ecoflex silicone-based hyperelastic elastomer. The influence of BTO on the Maxwell-Wiechert model parameters was studied through the stress relaxation results. While a pristine Ecoflex silicone elastomer is predominantly a hyperelastic material, the addition of BTO made the composite behave as a visco-hyperelastic material. However, this behavior was shown to have a negligible effect on the electrical sensing performance of the large strain sensor.</p

Studying the creep behaviour of strechable capacitive sensor with barium titanate silicone elastomer composite

In this paper, the creep behaviour of stretchable interdigital capacitive (IDC) large strain sensors is studied. A generalized Kelvin-Voigt (GKV) model is used to study the creep behaviour of the sensor's substrate material, manufactured from silicone elastomer (Ecoflex 00−30) with barium titanate (BTO) filler. Creep experiments are performed on sensors with 10, 20, 30 and 40 wt% BTO nanoparticles with dimensions of 100 nm and 200 nm dispersed in the elastomer. The BTO was used to increase the overall permittivity of the substrate, hence raising the capacitance of the IDC sensor. The effect of BTO on the GKV model parameters was studied in detail through analysis of the creep response. The pristine Ecoflex silicone elastomer is predominately a hyperelastic material, which shows negligible creep, while the addition of BTO particles led to the composite exhibiting creep such that the composite behaves like a visco-hyperelastic material. Hence, this behaviour results in the creep affecting the electrical sensing performance of the capacitive strain sensors during static loading conditions. This information provides insights on the impact of composite composition on creep-resistance and output signal of the sensor (capacitance).</p

A Frameshift in CSF2RB Predominant Among Ashkenazi Jews Increases Risk for Crohn's Disease and Reduces Monocyte Signaling via GMCSF

BACKGROUND & AIMS: Crohn's disease (CD) has the highest prevalence in Ashkenazi Jewish populations. We sought to identify rare, CD-associated frameshift variants of high functional and statistical effects. METHODS: We performed exome-sequencing and array-based genotype analyses of 1477 Ashkenazi Jewish individuals with CD and 2614 Ashkenazi Jewish individuals without CD (controls). To validate our findings, we performed genotype analyses of an additional 1515 CD cases and 7052 controls for frameshift mutations in the colony stimulating factor 2 receptor beta common subunit gene (CSF2RB). Intestinal tissues and blood samples were collected from patients with CD; lamina propria leukocytes were isolated and expression of CSF2RB and GMCSF-responsive cells were defined by mass cytometry (CyTOF analysis). Variants of CSF2RB were transfected into HEK293 cells and expression and functions of gene products were compared. RESULTS: In the discovery cohort, we associated CD with a frameshift mutation in CSF2RB (P=8.52x10-4); the finding was validated in the replication cohort (combined P=3.42x10-6). Incubation of intestinal lamina propria leukocytes with GMCSF resulted in high levels of phosphorylation of STAT5 and lesser increases in phosphorylation of ERK and AKT. Cells co-transfected with full-length and mutant forms of CSF2RB had reduced pSTAT5 following stimulation with GMCSF, compared to cells transfected with control CSF2RB, indicating a dominant negative effect of the mutant gene. Monocytes from patients with CD who were heterozygous for the frameshift mutation (6% of CD cases analyzed) had reduced responses to GMCSF and markedly decreased activity of aldehyde dehydrogenase; activity of this enzyme has been associated with immune tolerance. CONCLUSIONS: In a genetic analysis of Ashkenazi Jewish individuals, we associated CD with a frameshift mutation in CSF2RB. Intestinal monocytes from carriers of this mutation had reduced responses to GMCSF, providing an additional mechanism for alterations to the innate immune response in individuals with CD

Exploring synergies and trade-offs among the sustainable development goals: collective action and adaptive capacity in marginal mountainous areas of India

Global environmental change (GEC) threatens to undermine the sustainable development goals (SDGs). Smallholders in marginal mountainous areas (MMA) are particularly vulnerable due to precarious livelihoods in challenging environments. Acting collectively can enable and constrain the ability of smallholders to adapt to GEC. The objectives of this paper are: (i) identify collective actions in four MMA of the central Indian Himalaya Region, each with differing institutional contexts; (ii) assess the adaptive capacity of each village by measuring livelihood capital assets, diversity, and sustainable land management practices. Engaging with adaptive capacity and collective action literatures, we identify three broad approaches to adaptive capacity relating to the SDGs: natural hazard mitigation (SDG 13), social vulnerability (SDG 1, 2 and 5), and social–ecological resilience (SDG 15). We then develop a conceptual framework to understand the institutional context and identify SDG synergies and trade-offs. Adopting a mixed method approach, we analyse the relationships between collective action and the adaptive capacity of each village, the sites where apparent trade-offs and synergies among SDGs occur. Results illustrate each village has unique socio-environmental characteristics, implying distinct development challenges, vulnerabilities and adaptive capacities exist. Subsequently, specific SDG synergies and trade-offs occur even within MMA, and it is therefore crucial that institutions facilitate locally appropriate collective actions in order to achieve the SDGs. We suggest that co-production in the identification, prioritisation and potential solutions to the distinct challenges facing MMA can increase understandings of the specific dynamics and feedbacks necessary to achieve the SDGs in the context of GEC

Prosociality in business: a human empowerment framework

This study introduces a human empowerment framework to better understand why some businesses are more socially oriented than others in their policies and activities. Building on Welzel’s theory of emancipation, we argue that human empowerment—comprised of four components: action resources, emancipative values, social movement activity, and civic entitlements—enables, motivates, and entitles individuals to pursue social goals for their businesses. Using a sample of over 15,000 entrepreneurs from 43 countries, we report strong empirical evidence for two ecological effects of the framework components on prosociality. We find that human empowerment (1) lifts entrepreneurs’ willingness to choose a social orientation for their business, and (2) reinforces the gender effect on prosociality in business activity. We discuss the human empowerment framework’s added value in understanding how modernization processes fully leverage the potential of social business activities for societies

Population‐based cohort study of outcomes following cholecystectomy for benign gallbladder diseases

Background The aim was to describe the management of benign gallbladder disease and identify characteristics associated with all‐cause 30‐day readmissions and complications in a prospective population‐based cohort. Methods Data were collected on consecutive patients undergoing cholecystectomy in acute UK and Irish hospitals between 1 March and 1 May 2014. Potential explanatory variables influencing all‐cause 30‐day readmissions and complications were analysed by means of multilevel, multivariable logistic regression modelling using a two‐level hierarchical structure with patients (level 1) nested within hospitals (level 2). Results Data were collected on 8909 patients undergoing cholecystectomy from 167 hospitals. Some 1451 cholecystectomies (16·3 per cent) were performed as an emergency, 4165 (46·8 per cent) as elective operations, and 3293 patients (37·0 per cent) had had at least one previous emergency admission, but had surgery on a delayed basis. The readmission and complication rates at 30 days were 7·1 per cent (633 of 8909) and 10·8 per cent (962 of 8909) respectively. Both readmissions and complications were independently associated with increasing ASA fitness grade, duration of surgery, and increasing numbers of emergency admissions with gallbladder disease before cholecystectomy. No identifiable hospital characteristics were linked to readmissions and complications. Conclusion Readmissions and complications following cholecystectomy are common and associated with patient and disease characteristics

Cross Helicity Reversals in Magnetic Switchbacks

International audienceWe consider 2D joint distributions of normalized residual energy, sigma(r)(s, t), and cross helicity, sigma(c)(s, t), during one day of Parker Solar Probe's (PSP's) first encounter as a function of wavelet scale s. The broad features of the distributions are similar to previous observations made by Helios in slow solar wind, namely well-correlated and fairly Alfvenic wind, except for a population with negative cross helicity that is seen at shorter wavelet scales. We show that this population is due to the presence of magnetic switchbacks, or brief periods where the magnetic field polarity reverses. Such switchbacks have been observed before, both in Helios data and in Ulysses data in the polar solar wind. Their abundance and short timescales as seen by PSP in its first encounter is a new observation, and their precise origin is still unknown. By analyzing these MHD invariants as a function of the wavelet scale, we show that magnetohydrodynamic (MHD) waves do indeed follow the local mean magnetic field through switchbacks, with a net Elsasser flux propagating inward during the field reversal and that they, therefore, must be local kinks in the magnetic field and not due to small regions of opposite polarity on the surface of the Sun. Such observations are important to keep in mind as computing cross helicity without taking into account the effect of switchbacks may result in spurious underestimation of sigma(c) as PSP gets closer to the Sun in later orbits

The Radial Dependence of Proton-scale Magnetic Spectral Break in Slow Solar Wind during PSP Encounter 2

International audienceMagnetic field fluctuations in the solar wind are commonly observed to follow a power-law spectrum. Near proton-kinetic scales, a spectral break occurs that is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading to the onset of kinetic turbulence. Using data from the Parker Solar Probe, we measure the proton-scale break over a range of heliocentric distances, enabling a measurement of the transition from inertial to kinetic-scale turbulence under various plasma conditions. We find that the break frequency f(b) increases as the heliocentric distance r decreases in the slow solar wind following a power law of f(b) similar to r(-1.11). We also compare this to the characteristic plasma ion scales to relate the break to the possible physical mechanisms occurring at this scale. The ratio f(b)/f(c) (f(c) for Doppler-shifted ion cyclotron resonance scale) is close to unity and almost independent of plasma beta(p). While f(b)/f(p) (f(p) for Doppler-shifted proton thermal gyroradius) increases with beta(p) approaching to unity at larger beta(p), f(b)/f(d) (f(d) for Doppler-shifted proton inertial length) decreases with beta(p) from unity at small beta(p). Due to the large comparable Alfven and solar wind speeds, we analyze these results using both the standard and modified Taylor hypotheses, demonstrating the robust statistical results

Constraining Ion-Scale Heating and Spectral Energy Transfer in Observations of Plasma Turbulence

International audienceWe perform a statistical study of the turbulent power spectrum at inertial and kinetic scales observed during the first perihelion encounter of the Parker Solar Probe. We find that often there is an extremely steep scaling range of the power spectrum just above the ion-kinetic scales, similar to prior observations at 1 A.U., with a power-law index of around −4. Based on our measurements, we demonstrate that either a significant (>50%) fraction of the total turbulent energy flux is dissipated in this range of scales, or the characteristic nonlinear interaction time of the turbulence decreases dramatically from the expectation based solely on the dispersive nature of nonlinearly interacting kinetic Alfvén waves