Multiple Thresholds in a Model System of Noisy Ion Channels

Voltage-activated ion channels vary randomly between open and closed states, influenced by the membrane potential and other factors. Signal transduction is enhanced by noise in a simple ion channel model. The enhancement occurs in a finite range of signals; the range can be extended using populations of channels. The range increases more rapidly in multiple-threshold channel populations than in single-threshold populations. The diversity of ion channels may thus be present as a strategy to reduce the metabolic costs of handling a broad class of electrochemical signals.Comment: REVTeX 4, 5 pages, 4 figures; added paragrap

Introducing smart grids : practical experience of a DSO

One of the main issues for Distribution System Operators is the introduction of so-called smart grids. Enexis B.V., one of the major Distribution System Operators in The Netherlands started two years ago with the preparation of a large-scale roll-out of distribution automation, which can be considered as a part, or form of a smart grid. In the preparation and the pilot phase of the project it became clear however that a lot of practical issues had to be solved before smart grids can be rolled out. This contribution describes the experiences of Enexis and compares theory and practice of the introduction of smart grids

The Effectiveness of Online Stress Management Training Interventions: A Systematic Literature review

The central aim of this systematic literature review study was to investigate the effectiveness of online stress management training interventions that aimed to improve employees’ well-being. The study focused both on the effectiveness of online stress management training interventions and the sustainability of the intervention effects over time. Within this literature review 18 intervention studies, conducted worldwide among 3085 participants between 2002 and 2017, were evaluated. Methodological quality was examined using the Mixed Methods Appraisal Tool (MATT). In general, the main outcomes showed that most of the interventions turned out to be effective in decreasing employees’ levels of stress. In addition, some of these studies also revealed sustainability of intervention effects over time. This suggests that online stress management interventions are a promising tool for organizations to foster employee well-being

Primary umbilical endometriosis:a cause of a painful umbilical nodule

A female patient presented with a painful swelling in the umbilicus. Ultrasonography demonstrated a hypodense nodule of 1.8 cm. Surgical exploration revealed a subcutaneous, dark discoloured, lobulated swelling at the bottom of the umbilicus, which turned out to be primary umbilical endometriosis (PUE). Primary umbilical endometriosis is a rare and benign disorder, caused by the presence of ectopic endometrial tissue in the umbilicus, which can present as a painful, discoloured swelling in the umbilicus. The clinical distinction between primary umbilical endometrioses and other causes of an umbilical nodule is difficult. Additional imaging modalities do not show any pathognomonic signs for establishing this diagnose. Surgical exploration and excision are a safe and definitive treatment of primary umbilical endometrioses. This case highlights the importance of including PUE in the differential diagnosis of women with a painful umbilical nodule

Effective public relations in a transformed organisation : Naval Base Simon's Town as a case study

Thesis (MPA)--Stellenbosch University, 2002.ENGLISH ABSTRACT: Public Relations is a discipline where the basic concepts and functions remain the same, be it in a public or private organisation. It is ultimately a staff function, which is responsible for effective two-way communication between an organisation and its publics, both internal and external. With the transformation in the Department of Defence and ultimately the South African National Defence Force (SANDF), major changes took place structurally as well as in terms of the execution of functions on the operational level where Naval Base Simon’s Town (NB Smst) is one of the new General Support Bases of the SANDF. The Public Relations Section of NB Smst must deliver public relations services to the clients of NB Smst. The purpose of this study is to establish whether the services that the Public Relations Section delivers to its clients are in line with the expectations of the clients. An in-depth study is made of the theory of public relations, starting with the overall concept of communication. The transformation of the SANDF is discussed in detail and the concept of how public relations is supposed to be executed is researched. A needs assessment survey was done and the recommendations listed. The research established that although the Section is functioning in line with international and national principles and procedures the clients’ perceptions are that the Section does not deliver the quality of service they expect.AFRIKAANSE OPSOMMING: Openbare Skakeling is ’n dissipline waar die basiese konsepte en funksies ooreenstem binne publieke sowel as private organisasies. Dit is hoofsaaklik ’n staffunksie wat verantwoordelik is vir die effektiewe twee-rigting kommunikasie tussen ’n organisasie en sy publiek, beide intern sowel as ekstern. Met die transformasie van die Departement van Verdediging en uiteindelik die Suid- Afrikaanse Nasionale Weermag (SANW), het grootskaalse veranderinge plaasgevind, struktureel sowel as ten opsigte van die uitvoering van funksies op die operasionele vlak waar Vlootbasis Simonstad (VB Smst), een van die SANW se Algemene Steunbasisse, opereer. Die Openbare Skakelseksie van VB Smst is verantwoordelik vir die lewering van openbare skakeldienste aan die kliente van VB Smst. Die doel van hierdie studie is om te bepaal of die dienste wat deur die Openbare Skakelseksie gelewer word in lyn is met die kliente se verwagtinge. ’n In-diepte studie is gedoen ten opsigte van die teorie van openbare skakeling, beginnende met die totale konsep van kommunikasie. Die transformasie van die SANW word in detail bespreek. Dit word gevolg deur die navorsing oor hoe openbare skakeling veronderstel is om uitgevoer te word, ’n Behoeftebepaling is gedoen en aanbevelings word gelys. Die navorsing se bevindings is dat alhoewel die Seksie volgens internasionale en nasionale konsepte en prosedures funksioneer, die kliente se persepsies is dat die Seksie nie die kwaliteit dienste lewer wat hulle verwag nie

The one-carbon metabolism as an underlying pathway for placental DNA methylation - a systematic review

Epigenetic modifications, including DNA methylation, are proposed mechanisms explaining the impact of parental exposures to foetal development and lifelong health. Micronutrients including folate, choline, and vitamin B12 provide methyl groups for the one-carbon metabolism and subsequent DNA methylation processes. Placental DNA methylation changes in response to one-carbon moieties hold potential targets to improve obstetrical care. We conducted a systematic review on the associations between one-carbon metabolism and human placental DNA methylation. We included 22 studies. Findings from clinical studies with minimal ErasmusAGE quality score 5/10 (n = 15) and in vitro studies (n = 3) are summarized for different one-carbon moieties. Next, results are discussed per study approach: (1) global DNA methylation (n = 9), (2) genome-wide analyses (n = 4), and (3) gene specific (n = 14). Generally, one-carbon moieties were not associated with global methylation, although conflicting outcomes were reported specifically for choline. Using genome-wide approaches, few differentially methylated sites associated with S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), or dietary patterns. Most studies taking a gene-specific approach indicated site-specific relationships depending on studied moiety and genomic region, specifically in genes involved in growth and development including LEP, NR3C1, CRH, and PlGF; however, overlap between studies was low. Therefore, we recommend to further investigate the impact of an optimized one-carbon metabolism on DNA methylation and lifelong health