Approximating the influence coefficients of non-planar elastic solids for conformal contact analysis

The exact contact theory is an efficient alternative to the more general yet computationally expensive Finite Element Method for the detailed study of elastostatic contact problems. For its application in conformal contact problems, the exact contact theory needs to be fed with influence coefficients (ICs) appropriate for non-planar solids. An analytical approximation of the ICs for non-planar solids was proposed in a previous work, avoiding the involved process generally necessary to obtain ICs accurately. This work presents further developments of this approximation, further comparison with numerically obtained ICs, and evaluates the errors incurred when using approximated ICs in conformal contact.This work has been partly financed within the European Horizon 2020 Joint Technology Initiative Shift2Rail, through contract no. 826255 (IN2TRACK2). The authors wish to thank as well the Spanish Research Ministry MICINN/Economy and Competitiveness Ministry MINECO and MCI/AEI for their funding through contracts TRA2014-59599-R and PID2019-109483RB-I00, including funding by the FEDER-ERDF European Regional Development Fund, and also the Basque Government for financial assistance through IT919-1

Ketenkwaliteit in de hand

Binnen de voedseltechnologie is het van belang te weten hoe goed een keten in staat is de kwaliteit van het versproduct vast te houden. Om inzicht te krijgen in de prestatie van een keten is de 'vers-keten prestatie-index' ontwikkeld, waarvan in het kort wordt uitgelegd hoe deze te gebruike

Houdbaarheid en koeling, groentegewassen : eindrapportage 2004

De afgelopen jaren zijn de koelketens in het naoogsttraject van groenten en fruit sterk veranderd. Ketens zijn korter geworden, de doorlooptijden van producten eveneens. Wat is het effect van koelen nog in deze ketens? Is koelen nog wel nodig, is snelheid niet veel belangrijker? En geldt dat voor alle producten? Het project HenK (Houdbaarheid en Koeling) gaat in op deze vragen. Van de geselecteerde producten is nagegaan hoe de aanvoer over het jaar is verdeeld: De aanvoer van aardbei, paprika, tomaat en ijsbergsla loopt parallel aan de buitentemperatuur: meer aanvoer bij hogere buitentemperatuur. De aanvoer van witlof is niet afhankelijk van de buitentemperatuur, de koelbehoefte van witlof is voor relatief een klein deel afhankelijk van de buitentemperatuur. Het is zeer onduidelijk wat in de huidige praktijk realistische ethyleenconcentraties zijn

Can serial cerebral MRIs predict the neuronopathic phenotype of MPS II?

OBJECTIVE: To advance the prediction of the neurocognitive development in MPS II patients by jointly analyzing MRI and neurocognitive data in mucopolysaccharidosis (MPS) II patients. METHODS: Cognitive ability scores (CAS) were obtained by neuropsychological testing. Cerebral MRIs were quantified using a disease‐specific protocol. MRI sumscores were calculated for atrophy, white‐matter abnormalities (WMA) and Virchow‐Robin spaces (VRS). To distinguish between atrophy and hydrocephalus the Evans' index and the callosal angle (CA) were measured. A random effects repeated measurement model was used to correlate CAS with the three MRI sumscores. RESULTS: MRI (n = 47) and CAS scores (n = 78) of 19 male patients were analyzed. Ten patients were classified as neuronopathic and nine as non‐neuronopathic. Neuronopathic patients had normal cognitive development until age 3 years. Mental age plateaued between ages 3 and 6, and subsequently declined with loss of skills at a maximum developmental age of 4 years. MRIs of neuronopathic patients showed abnormal atrophy sumscores before CAS dropped below the threshold for intellectual disability (<70). White‐matter abnormalities (WMA) and brain atrophy progressed. The calculated sumscores were inversely correlated with CAS (r = −.90 for atrophy and −.69 for WMA). This was not biased by the influence of hydrocephalus as shown by measurement of the Evans' and callosal angle. Changes over time in the Virchow‐Robin spaces (VRS) on MRI were minimal. CONCLUSION: In our cohort, brain atrophy showed a stronger correlation to a decline in CAS when compared to WMA. Atrophy‐scores were higher in young neuronopathic patients than in non‐neuronopathic patients and atrophy was an important early sign for the development of the neuronopathic phenotype, especially when observed jointly with white‐matter abnormalities

Efficacy and mechanism of sub-sensory sacral (optimised) neuromodulation in adults with faecal incontinence:Study protocol for a randomised controlled trial

Background: Faecal incontinence (FI) is a substantial health problem with a prevalence of approximately 8% in community-dwelling populations. Sacral neuromodulation (SNM) is considered the first-line surgical treatment option in adults with FI in whom conservative therapies have failed. The clinical efficacy of SNM has never been rigorously determined in a trial setting and the underlying mechanism of action remains unclear. Methods/design: The design encompasses a multicentre, randomised, double-blind crossover trial and cohort follow-up study. Ninety participants will be randomised to one of two groups (SNM/SHAM or SHAM/SNM) in an allocation ratio of 1:1. The main inclusion criteria will be adults aged 18-75 years meeting Rome III and ICI definitions of FI, who have failed non-surgical treatments to the UK standard, who have a minimum of eight FI episodes in a 4-week screening period, and who are clinically suitable for SNM. The primary objective is to estimate the clinical efficacy of sub-sensory SNM vs. SHAM at 32 weeks based on the primary outcome of frequency of FI episodes using a 4-week paper diary, using mixed Poisson regression analysis on the intention-to-treat principle. The study is powered (0.9) to detect a 30% reduction in frequency of FI episodes between sub-sensory SNM and SHAM stimulation over a 32-week crossover period. Secondary objectives include: measurement of established and new clinical outcomes after 1 year of therapy using new (2017 published) optimised therapy (with standardised SNM-lead placement); validation of new electronic outcome measures (events) and a device to record them, and identification of potential biological effects of SNM on underlying anorectal afferent neuronal pathophysiology (hypothesis: SNM leads to increased frequency of perceived transient anal sphincter relaxations; improved conscious sensation of defaecatory urge and cortical/subcortical changes in afferent responses to anorectal electrical stimulation (main techniques: high-resolution anorectal manometry and magnetoencephalography). Discussion: This trial will determine clinical effect size for sub-sensory chronic electrical stimulation of the sacral innervation. It will provide experimental evidence of modifiable afferent neurophysiology that may aid future patient selection as well as a basic understanding of the pathophysiology of FI

The London Classification: Improving Characterization and Classification of Anorectal Function with Anorectal Manometry.

PURPOSE OF REVIEW: Objective measurement of anorectal sensorimotor function is a requisite component in the clinical evaluation of patients with intractable symptoms of anorectal dysfunction. Regrettably, the utility of the most established and widely employed investigations for such measurement (anorectal manometry (ARM), rectal sensory testing and the balloon expulsion test) has been limited by wide variations in clinical practice. RECENT FINDINGS: This article summarizes the recently published International Anorectal Physiology Working Group (IAPWG) consensus and London Classification of anorectal disorders, together with relevant allied literature, to provide guidance on the indications for, equipment, protocol, measurement definitions and results interpretation for ARM, rectal sensory testing and the balloon expulsion test. The London Classification is a standardized method and nomenclature for description of alterations in anorectal motor and sensory function using office-based investigations, adoption of which should bring much needed harmonization of practice

A General Approach for Predicting the Filtration of Soft and Permeable Colloids: The Milk Example

Membrane filtration operations (ultra-, microfiltration) are now extensively used for concentrating or separating an ever-growing variety of colloidal dispersions. However, the phenomena that determine the efficiency of these operations are not yet fully understood. This is especially the case when dealing with colloids that are soft, deformable, and permeable. In this paper, we propose a methodology for building a model that is able to predict the performance (flux, concentration profiles) of the filtration of such objects in relation with the operating conditions. This is done by focusing on the case of milk filtration, all experiments being performed with dispersions of milk casein micelles, which are sort of ″natural″ colloidal microgels. Using this example, we develop the general idea that a filtration model can always be built for a given colloidal dispersion as long as this dispersion has been characterized in terms of osmotic pressure Π and hydraulic permeability k. For soft and permeable colloids, the major issue is that the permeability k cannot be assessed in a trivial way like in the case for hard-sphere colloids. To get around this difficulty, we follow two distinct approaches to actually measure k: a direct approach, involving osmotic stress experiments, and a reverse-calculation approach, that consists of estimating k through well-controlled filtration experiments. The resulting filtration model is then validated against experimental measurements obtained from combined milk filtration/SAXS experiments. We also give precise examples of how the model can be used, as well as a brief discussion on the possible universality of the approach presented here