Development of an optoelectronic test station for novel phasechange device characterisation and development

This is the final version of the article. Available from E\PCOS via the URL in this record.Optoelectronic applications of phase-change devices are of increasing interest and importance. To enable the proper experimental characterisation of device optoelectronic properties, and to allow for the future development of device designs with improved optoelectronic performance, we have constructed an optoelectronic test station that can simultaneously measure the optical and electrical properties of phase-change devices with high optical resolution and with high electrical bandwidths. The design of this test station, and some preliminary test applications are described

Reconfigurable phase-change meta-absorbers with on-demand quality factor control

This is the final version. Available on open access from Optical Society of America via the DOI in this recordData accessibility: Supporting data for this manuscript is available from the corresponding author.Perfect absorber type devices are well-suited to many applications, such as solar cells, spatial light modulators, bio-sensors, and highly-sensitive photo-detectors. In such applications, a method for the design and fabrication of devices in a simple and efficient way, while at the same time maintaining design control over the key performance characteristics of resonant frequency, reflection coefficient at resonance and quality factor, would be particularly advantageous. In this work we develop such a method, based on eigenmode analysis and critical coupling theory, and apply it to the design of reconfigurable phase-change metasurface absorber devices. To validate the method, the design and fabrication of a family of absorbers was carried out with a range of ‘on-demand’ quality factors, all operating at the same resonant frequency and able to be fabricated simply and simultaneously on the same chip. Furthermore, by switching the phase-change layer between its amorphous and crystalline states, we show that our devices can provide an active or reconfigurable functionality.Office of Naval Research (ONR)Engineering and Physical Sciences Research Council (EPSRC)Office of Naval Research (ONR

Mixed-Mode Electro Optical Properties of Ge2Sb2Te5

This is the author accepted manuscript.In this paper we present ongoing work on a novel alternative mode of operation of phase change materials, specifically Ge2Sb2Te5: mixed-mode electro-optical operation, which offers a new set of potential applications for this material

A nonvolatile phase-change metamaterial color display

This is the final version. Available from Wiley via the DOI in this record.Chalcogenide phase-change materials, which exhibit a marked difference in their electrical and optical properties when in their amorphous and crystalline phases and can be switched between these phases quickly and repeatedly, are traditionally exploited to deliver nonvolatile data storage in the form of rewritable optical disks and electrical phase-change memories. However, exciting new potential applications are now emerging in areas such as integrated phase-change photonics, phase-change optical metamaterials/metasurfaces, and optoelectronic displays. Here, ideas from these last two fields are fused together to deliver a novel concept, namely a switchable phase-change metamaterial/metasurface resonant absorber having nonvolatile color generating capabilities. With the phase-change layer, here GeTe, in the crystalline phase, the resonant absorber can be tuned to selectively absorb the red, green, and blue spectral bands of the visible spectrum, so generating vivid cyan, magenta, and yellow pixels. When the phase-change layer is switched into the amorphous phase, the resonant absorption is suppressed and a flat, pseudowhite reflectance results. Thus, a route to the potential development is opened-up of nonvolatile, phase-change metamaterial color displays and color electronic signage.Engineering and Physical Sciences Research Council (EPSRC

Novel applications possibilities for phase-change materials and devices

Paper presented at European\Phase Change and Ovonics Symposium 2013, 2013-09-08, 2013-09-10, BerlinPhase-change materials and devices are most widely known for their use in optical and electrical non-volatile memory applications. Recently however the potential has been demonstrated for using phase-change materials and devices for a range of novel applications, including the provision of electronic 'mimics' of biological synapses and neurons (and their associated use in neuromorphic computing) and the provision of arithmetic and logic functionality. Furthermore, such neuromorphic, arithmetic and logic capabilities of phase-change materials and devices are accessible in both the optical (photonic) and the electrical (electronic) domains, or indeed via a 'mixed-mode' approach in which excitation is in the optical domain and detection is electrical, or vice-versa. This versatility of operation opens up the route towards various intriguing possibilities, such as 'all-optical' memory and computing devices, or the development of an optical analogue of the memristor, the so-called 'memflector'. In this paper we discuss such novel applications possibilities for phase-change materials and devices and present proof-of-principle of some of the underlying concepts

Phase-change metadevices for the dynamic and reconfigurable control of light

This is the author accepted manuscript. The final version is available from Optical Society of America via the DOI in this recordNovel Optical Materials and Applications 2018, 2–5 July 2018, Zurich, SwitzerlandThe combination of chalcogenide phase-change materials with optical metamaterial arrays is exploited to create new forms of dynamic, tuneable and reconfigurable photonic devices including perfect absorbers, modulators, beam steerers and filters.CDW and VKN acknowledge ONRG funding (#N62909-16-1-2174). CDW, AMA, Y-YA, VKN acknowledge EPSRC funding EP/M015130/1 & EP/M015173/1. CrdeG, SG-CC, EG and LT the EPSRC CDT in Metamaterials (EP/L015331/1). LT acknowledges support from QinetiQ. MLG acknowledges EPSRC funding EP/M009033/1

An Exome-Chip Association Analysis in Chinese Subjects Reveals a Functional Missense Variant of GCKR That Regulates FGF21 Levels

Fibroblast growth factor 21 (FGF21) is increasingly recognized as an important metabolic regulator of glucose homeostasis. Here, we conducted an exome-chip association analysis by genotyping 5,169 Chinese individuals from a community-based cohort and two clinic-based cohorts. A custom Asian exome-chip was used to detect genetic determinants influencing circulating FGF21 levels. Single-variant association analysis interrogating 70,444 single nucleotide polymorphisms identified a novel locus, GCKR, significantly associated with circulating FGF21 levels at genome-wide significance. In the combined analysis, the common missense variant of GCKR, rs1260326 (p.Pro446Leu), showed an association with FGF21 levels after adjustment for age and sex (P = 1.61 × 10−12; β [SE] = 0.14 [0.02]), which remained significant on further adjustment for BMI (P = 3.01 × 10−14; β [SE] = 0.15 [0.02]). GCKR Leu446 may influence FGF21 expression via its ability to increase glucokinase (GCK) activity. This can lead to enhanced FGF21 expression via elevated fatty acid synthesis, consequent to the inhibition of carnitine/palmitoyl-transferase by malonyl-CoA, and via increased glucose-6-phosphate–mediated activation of the carbohydrate response element binding protein, known to regulate FGF21 gene expression. Our findings shed new light on the genetic regulation of FGF21 levels. Further investigations to dissect the relationship between GCKR and FGF21, with respect to the risk of metabolic diseases, are warranted.postprin

Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study.

To validate the clinical efficacy and practical feasibility of massively parallel maternal plasma DNA sequencing to screen for fetal trisomy 21 among high risk pregnancies clinically indicated for amniocentesis or chorionic villus sampling. Diagnostic accuracy validated against full karyotyping, using prospectively collected or archived maternal plasma samples. Prenatal diagnostic units in Hong Kong, United Kingdom, and the Netherlands. 753 pregnant women at high risk for fetal trisomy 21 who underwent definitive diagnosis by full karyotyping, of whom 86 had a fetus with trisomy 21. Intervention Multiplexed massively parallel sequencing of DNA molecules in maternal plasma according to two protocols with different levels of sample throughput: 2-plex and 8-plex sequencing. Proportion of DNA molecules that originated from chromosome 21. A trisomy 21 fetus was diagnosed when the z score for the proportion of chromosome 21 DNA molecules was >3. Diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were calculated for trisomy 21 detection. Results were available from 753 pregnancies with the 8-plex sequencing protocol and from 314 pregnancies with the 2-plex protocol. The performance of the 2-plex protocol was superior to that of the 8-plex protocol. With the 2-plex protocol, trisomy 21 fetuses were detected at 100% sensitivity and 97.9% specificity, which resulted in a positive predictive value of 96.6% and negative predictive value of 100%. The 8-plex protocol detected 79.1% of the trisomy 21 fetuses and 98.9% specificity, giving a positive predictive value of 91.9% and negative predictive value of 96.9%. Multiplexed maternal plasma DNA sequencing analysis could be used to rule out fetal trisomy 21 among high risk pregnancies. If referrals for amniocentesis or chorionic villus sampling were based on the sequencing test results, about 98% of the invasive diagnostic procedures could be avoided.published_or_final_versio

Symptomatic hypopituitarism revealing primary suprasellar lymphoma

<p>Abstract</p> <p>Background</p> <p>The most common cause of hypopituitarism is pituitary adenoma. However, in the case of suprasellar masses different etiologies are possible. We report an unusual case of primary suprasellar lymphoma presented with hypopituitarism.</p> <p>Case presentation</p> <p>A 26 year old woman presented with amenorrhea, galactorrhea and neurological disorders. Also, the laboratory work-up revealed partial hypopituitarism. The magnetic resonance imaging of the head showed a suprasellar mass. A presumptive diagnosis of granulomatous processes was made and the patient was given steroid therapy. Repeated brain MRI detected new lesions in the brain with regression of the suprasellar mass. Stereotactic biopsy of the paraventricular lesion revealed the diagnosis of B-cell lymphoma.</p> <p>Conclusion</p> <p>This case presentation reports a rare cause of hypopituitarism. Primary suprasellar lymphoma is extremely rare and represented a real diagnostic challenge. Besides, suprasellar masses are varied in aetiology and can present diagnostic problems for a radiologist. Also, because of the increased incidence of PCNSL, lymphoma must be kept in mind in the differential diagnosis of lesions in the suprasellar region.</p

Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation