Wavelength Drift in CWDM Systems: Impact and Measurement

The research begins with an investigation of wavelength drift in Coarse Wavelength Division Multiplexing (CWDM) systems, especially in the context of temperature dependent wavelength drift. A simple model was proposed using a typical ‘application’ from ITU-T G.695. OptiSystem was chosen as the simulation platform due to its ease of use, the variety and flexibility of its inbuilt components and similar models simulated on the platform in the past. The research then investigates the measurement of wavelength drift focusing on how to determine an acceptable wavelength accuracy for a CWDM wavelength monitor. The chosen approach arose from observations of the results from a model of how wavelength drift impacts the most important system parameter in CWDM systems, which is error performance. The statistical confidence levels of Bit Error Ratio (BER) measurements taken by typical industry test and measurement equipment was considered and their statistical worst case BER results were calculated. An argument is made equating wavelength drift to an equivalent degradation of a links BER. Using the model developed a minimum wavelength accuracy of 0.1365 nm for the CWDM wavelength monitor was calculated. Following a survey of instruments marketed to the CWDM industry, a set of attributes that are representative of the different types of instruments available was made. These attributes were categorised into parameters and features. Each parameter and feature was considered in the context of a wavelength monitor for use in CWDM systems with a subsequent reclassification of the attributes into ‘essential features’ and ‘key parameters’, hence the attributes of a CWDM wavelength monitor were specified. An in-depth investigation of wavelength measurement operating principles was carried out with the aim of identifying a suitable technology to implement a CWDM wavelength monitor. The ratiometric wavelength measurement operating principle was chosen to implement a proof of principle CWDM wavelength monitor as it offers the best potential to meet the required specification with a least complex solution. The ratiometric wavelength measurement operating principle was discussed in more detail followed by an investigation of the maximum discrimination of the optical filter used in this technique. The limits on the maximum discrimination of the optical filter due to an optical sources wideband noise were then modelled with a proof of principle experiment carried out to validate the model

Online Quiz

Three sets of multiple choice (primarily) quizzes, 20 mins, 20 questions, open book, 3 weeks (unsupervised), single attempt. There is a question bank consisting of 40 questions, each quiz selects 20 of these 40, thus students will not receive the same questions in the same order

The validity of using a simulated baby as part of a sex education programme

Rates of teenage pregnancy in Scotland for those under the age of sixteen, have not fallen significantly over the past ten years. Teenage pregnancy is associated with depression, low self-esteem, poverty and low achievement at school. Research also suggests that it leads to poorer physical and mental health outcomes, not only for the teenage parent, but also for their offspring (Coley & Chase-Lansdale, 1998; Jessor, Turbins & Costa, 1998; Nitz, 1999; Trad, 1999). In order to address teenage pregnancy, sex education is taught in all secondary schools. Research suggests that teenagers want sex education, which includes effective methods of increasing self-esteem and confidence, as well as factual information (Burns, 1999; Coleman & Hendry, 1999; Meyrick & Harris, 1994). Recently, simulated babies have been produced, with the explicit idea of being used within the context of sex education classes. However, there is a paucity of research on this as an effective tool, and research that has been conducted has not been done within the context of sex education (Hart, Cochrane & Quinn, 2000; Kralewski & Stevens-Simon, 2000; Price, 2000; Strachan & Gorey, 1997).This study aimed to examine whether a simulated baby was an effective tool in the context of a sex education class, for fourteen year old pupils, in a secondary school in Inverness, Scotland. An experimental group was compared with a control group x using a sexual health questionnaire, which was constructed for the purpose, the Culture-Free Self-Esteem Inventory - 2nd Edition (CFSEI-2, Form A), and the Locus of Control Scale for Children (LCSC). Interviews were also conducted. Data were collected at three data collection points: prior to the study taking place, after the study, and at a nine month follow-up. Quantitative data showed little statistical significance, however qualitative data showed interesting results. Results are presented and discussed, and conclusions are drawn

Amyloid-β nanotubes are associated with prion protein-dependent synaptotoxicity

Growing evidence suggests water-soluble, non-fibrillar forms of amyloid-β protein (Aβ) have important roles in Alzheimer’s disease with toxicities mimicked by synthetic Aβ1–42. However, no defined toxic structures acting via specific receptors have been identified and roles of proposed receptors, such as prion protein (PrP), remain controversial. Here we quantify binding to PrP of Aβ1–42 after different durations of aggregation. We show PrP-binding and PrP-dependent inhibition of long-term potentiation (LTP) correlate with the presence of protofibrils. Globular oligomers bind less avidly to PrP and do not inhibit LTP, whereas fibrils inhibit LTP in a PrP-independent manner. That only certain transient Aβ assemblies cause PrP-dependent toxicity explains conflicting reports regarding the involvement of PrP in Aβ-induced impairments. We show that these protofibrils contain a defined nanotubular structure with a previously unidentified triple helical conformation. Blocking the formation of Aβ nanotubes or their interaction with PrP might have a role in treatment of Alzheimer’s disease

Amyloid-β nanotubes are associated with prion protein-dependent synaptotoxicity

Growing evidence suggests water-soluble, non-fibrillar forms of amyloid-β protein (Aβ) have important roles in Alzheimer's disease with toxicities mimicked by synthetic Aβ1-42. However, no defined toxic structures acting via specific receptors have been identified and roles of proposed receptors, such as prion protein (PrP), remain controversial. Here we quantify binding to PrP of Aβ1-42 after different durations of aggregation. We show PrP-binding and PrP-dependent inhibition of long-term potentiation (LTP) correlate with the presence of protofibrils. Globular oligomers bind less avidly to PrP and do not inhibit LTP, whereas fibrils inhibit LTP in a PrP-independent manner. That only certain transient Aβ assemblies cause PrP-dependent toxicity explains conflicting reports regarding the involvement of PrP in Aβ-induced impairments. We show that these protofibrils contain a defined nanotubular structure with a previously unidentified triple helical conformation. Blocking the formation of Aβ nanotubes or their interaction with PrP might have a role in treatment of Alzheimer's disease

Single-molecule imaging reveals that small amyloid-β1-42 oligomers interact with the cellular prion protein (PrP(C)).

Oligomers of the amyloid-β peptide (Aβ) play a central role in the pathogenesis of Alzheimer's disease and have been suggested to induce neurotoxicity by binding to a plethora of cell-surface receptors. However, the heterogeneous mixtures of oligomers of varying sizes and conformations formed by Aβ42 have obscured the nature of the oligomeric species that bind to a given receptor. Here, we have used single-molecule imaging to characterize Aβ42 oligomers (oAβ42) and to confirm the controversial interaction of oAβ42 with the cellular prion protein (PrP(C)) on live neuronal cells. Our results show that, at nanomolar concentrations, oAβ42 interacts with PrP(C) and that the species bound to PrP(C) are predominantly small oligomers (dimers and trimers). Single-molecule biophysical studies can thus aid in deciphering the mechanisms that underlie receptor-mediated oAβ-induced neurotoxicity, and ultimately facilitate the discovery of novel inhibitors of these pathways.This is the final published version. It was first published by Wiley in ChemBioChem (http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1439-7633)

Non-fibrillar oligomeric amyloid-β within synapses

Alzheimer’s disease (AD) is characterized by memory loss, insidious cognitive decline, profound neurodegeneration, and the extracellular accumulation of amyloid-β (Aβ) peptide in senile plaques and intracellular accumulation of tau in neurofibrillary tangles. Loss and dysfunction of synapses are believed to underlie the devastating cognitive decline in AD. A large amount of evidence suggests that oligomeric forms of Aβ associated with senile plaques are toxic to synapses, but the precise sub-synaptic localization of Aβ and which forms are synaptotoxic remain unknown. Here, we characterize the sub-synaptic localization of Aβ oligomers using three high-resolution imaging techniques, stochastic optical reconstruction microscopy, immunogold electron microscopy, and Förster resonance energy transfer in a plaque-bearing mouse model of AD. With all three techniques, we observe oligomeric Aβ inside synaptic terminals. Further, we tested a panel of Aβ antibodies using the relatively high-throughput array tomography technique to determine which forms are present in synapses. Our results show that different oligomeric Aβ species are present in synapses and highlight the potential of array tomography for rapid testing of aggregation state specific Aβ antibodies in brain tissue

Effects of Aβ exposure on longterm associative memory and its neuronal mechanisms in a defined neuronal network

Amyloid beta (Aβ ) induced neuronal death has been linked to memory loss, perhaps the most devastating symptom of Alzheimer’s disease (AD). Although Aβ -induced impairment of synaptic or intrinsic plasticity is known to occur before any cell death, the links between these neurophysiological changes and the loss of specific types of behavioral memory are not fully understood. Here we used a behaviorally and physiologically tractable animal model to investigate Aβ -induced memory loss and electrophysiological changes in the absence of neuronal death in a defined network underlying associative memory. We found similar behavioral but different neurophysiological effects for Aβ 25-35 and Aβ 1-42 in the feeding circuitry of the snail Lymnaea stagnalis. Importantly, we also established that both the behavioral and neuronal effects were dependent upon the animals having been classically conditioned prior to treatment, since Aβ application before training caused neither memory impairment nor underlying neuronal changes over a comparable period of time following treatment

Investigation of Macrobending Losses of Standard Single Mode Fiber with Small Bend Radii

An investigation of macrobending loss characteristics of a standard singlemode fiber (SMF28) for small bend radii is presented theoretically and experimentally, which includes the bend loss of the SMF28 with coating layers and the bare SMF28 after stripping the coating layers and chemical etching of partial cladding. The significant influence of reflection occurring at the interface between the cladding and coating layer or the cladding layer and air on the bend loss is investigated theoretically and experimentally

Silent Harm. A training manual for service providers and interpreters who work with deaf, refugee, and migrant women and girls who have experienced gender-based violence

Introduction: The handbook presented here is one of the results of the Justisigns2 project, which was developed to address an important interpreter-mediated communications gap, namely: the need to share information about how to communicate effectively, via interpretation, with deaf and migrant women, refugees or asylum-seekers, victims/survivors of gender-based violence (DSGBV) who use languages other than the official languages of their host states. This gave rise to an analysis of need on the part of service providers and the creation of resources to support service providers working with victims/survivors across a range of sectors (e.g.police-court, social-health and NGO settings) and the interpreters who mediate the communicative exchanges with these victims/survivors. The Justisigns2 project was funded by the Erasmus+program (ref. 2019-1-IE01-KA202-051558) and was carried out by the following project partners: Interesource Group (Ireland), European Union of the Deaf, Trinity College Dublin, Dublin Rape Crisis Centre, An Garda Síochána,Heriot-Watt University and the Universidade de Vigo, with support from a number of organisations and individuals (associate partners). This handbook builds on the results of a survey that was conducted in 2021 (Napier et al. 2022) that invited engagement from interpreters and a broad range of service providers working with deaf or migrant DSGBV victims. This yielded extensive and varied data on the needs of such groups in the three countries surveyed (Ireland, Spain and the United Kingdom). For the purposes of this publication, the focus is on violence against women and girls. It is important to acknowledge that DSGBV is violence directed against a person because of that person’s gender or violence that affects persons of a particular gender disproportionately. Given that sociolinguistic contexts and legislative frameworks vary in the different project partner countries, a general definition of DSGBV is first provided and then the differences that exist in the 3 countries surveyed (Ireland, UK and Spain) are discussed. For example, the term gender-based violence is not widely used in the UK where the term Violence against Women and Girls (VAWG) is in use. As a result, the term Domestic, Sexual and Gender-based violence (DSGBV) is used here