Proposal for an analog CMOS median filter system based on neural network architectural principles

This thesis summarizes the investigation of a proposed analog electronic CMOS system for performing median filtering. A description of the problem and rational for investigating neural networks are given followed by a review of recent efforts toward solving the median filtering problem in hardware. A review of the major developments in hardware neural networks is also presented followed by the system proposal. A comparator design intended to function as a major building block is presented and analyzed. A description of efforts to accurately model the comparator follows. A Spice macro model simulation was assembled as well as a dedicated Runge-Kutta system level simulation. The two models were used to evaluate the system's performance when asked to perform median filtering on a number of different types of input data sets. Methods for predicting the behavior of the system are proposed and compared to simulation results. Finally, conclusions and suggestions for future investigations are offered based on the reported simulation results. A large amount of time was spent on putting the necessary software in place to do the work that this thesis summarizes. Difficulties with incompatible spice models, curve fitters. pre-production software versions, and communication links between computers abounded. In spite of all these obstacles, some meaningful data was finally generated allowing the conclusion of this effort.Electrical Engineerin

Persistence of full glacial conditions in the central Pacific until 15,000 years ago

The magnitude of atmospheric cooling during the Last Glacial Maximum and the timing of the transition into the current interglacial period remain poorly constrained in tropical regions, partly because of a lack of suitable climate records. Glacial moraines provide a method of reconstructing past temperatures, but they are relatively rare in the tropics. Here we present a reconstruction of atmospheric temperatures in the central Pacific during the last deglaciation on the basis of cosmogenic ^3He ages of moraines and numerical modelling of the ice cap on Mauna Kea volcano, Hawaii—the only highland in the central Pacific on which moraines that formed during the last glacial period are preserved. Our reconstruction indicates that the Last Glacial Maximum occurred between 19,000 and 16,000 years ago in this region and that temperatures at high elevations were about 7 °C lower than today during this interval. Glacial retreat began about 16,000 years ago, but temperatures were still about 6.5 °C lower than today until 15,000 years ago. When combined with estimates of sea surface temperatures in the central Pacific Ocean, our reconstruction indicates that the lapse rate during the Last Glacial Maximum was higher than at present, which is consistent with the proposal that the atmosphere was drier at that time. Furthermore, the persistence of full glacial conditions until 15,000 years ago is consistent with the relatively late and abrupt transition to warmer temperatures in Greenland5, indicating that there may have been an atmospheric teleconnection between the central Pacific and North Atlantic regions during the last deglaciation

A physically based 3-D model of ice cliff evolution over debris-covered glaciers

We use high-resolution digital elevation models (DEMs) from unmanned aerial vehicle (UAV) surveys to document the evolution of four ice cliffs on the debris-covered tongue of Lirung Glacier, Nepal, over one ablation season. Observations show that out of four cliffs, three different patterns of evolution emerge: (i) reclining cliffs that flatten during the ablation season; (ii) stable cliffs that maintain a self-similar geometry; and (iii) growing cliffs, expanding laterally. We use the insights from this unique data set to develop a 3-D model of cliff backwasting and evolution that is validated against observations and an independent data set of volume losses. The model includes ablation at the cliff surface driven by energy exchange with the atmosphere, reburial of cliff cells by surrounding debris, and the effect of adjacent ponds. The cliff geometry is updated monthly to account for the modifications induced by each of those processes. Model results indicate that a major factor affecting the survival of steep cliffs is the coupling with ponded water at its base, which prevents progressive flattening and possible disappearance of a cliff. The radial growth observed at one cliff is explained by higher receipts of longwave and shortwave radiation, calculated taking into account atmospheric fluxes, shading, and the emission of longwave radiation from debris surfaces. The model is a clear step forward compared to existing static approaches that calculate atmospheric melt over an invariant cliff geometry and can be used for long-term simulations of cliff evolution and to test existing hypotheses about cliffs' survival

Meteorological impacts of a novel debris-covered glacier category in a regional climate model across a Himalayan catchment

Many of the glaciers in the Nepalese Himalaya are partially covered in a layerof loose rock known as debris cover. In the Dudh Koshi River Basin, Nepal,approximately 25% of glaciers are debris-covered. Debris-covered glaciers havebeen shown to have a substantial impact on near-surface meteorological vari-ables and the surface energy balance, in comparison to clean-ice glaciers. TheWeather Research and Forecasting (WRF) model is often used for high-resolution weather and climate modelling, however representation of debris-covered glaciers is not included in the standard land cover and soil categories.Here we include a simple representation of thick debris-covered glaciers in theWRF model, and investigate the impact on the near-surface atmosphere overthe Dudh Koshi River Basin for July 2013. Inclusion of this new category isfound to improve the model representation of near-surface temperature andrelative humidity, in comparison with a simulation using the default categoryof clean-ice glaciers, when compared to observations. The addition of the newdebris-cover category in the model warms the near-surface air over the debris-covered portion of the glacier, and the wind continues further up the valley,compared to the simulation using clean-ice. This has consequent effects onwater vapour and column-integrated total water path, over both the portions ofthe glacier with and without debris cover. Correctly simulating meteorologicalvariables such as these is vital for accurate precipitation forecasts overglacierized regions, and therefore estimating future glacier melt and river run-off in the Himalaya. These results highlight the need for debris cover to be included in high-resolution regional climate models over debris-covered glaciers.NER

Ice cliff contribution to the tongue-wide ablation of Changri Nup Glacier, Nepal, central Himalaya

Ice cliff backwasting on debris-covered glaciers is recognized as an important mass-loss process that is potentially responsible for the debris-cover anomaly, i.e. the fact that debris-covered and debris-free glacier tongues appear to have similar thinning rates in the Himalaya. In this study, we quantify the total contribution of ice cliff backwasting to the net ablation of the tongue of Changri Nup Glacier, Nepal, between 2015 and 2017. Detailed backwasting and surface thinning rates were obtained from terrestrial photogrammetry collected in November 2015 and 2016, unmanned air vehicle (UAV) surveys conducted in November 2015, 2016 and 2017, and Pléiades tri-stereo imagery obtained in November 2015, 2016 and 2017. UAV- and Pléiades-derived ice cliff volume loss estimates were 3&thinsp;% and 7&thinsp;% less than the value calculated from the reference terrestrial photogrammetry. Ice cliffs cover between 7&thinsp;% and 8&thinsp;% of the total map view area of the Changri Nup tongue. Yet from November 2015 to November 2016 (November 2016 to November 2017), ice cliffs contributed to 23±5&thinsp;% (24±5&thinsp;%) of the total ablation observed on the tongue. Ice cliffs therefore have a net ablation rate 3.1±0.6 (3.0±0.6) times higher than the average glacier tongue surface. However, on Changri Nup Glacier, ice cliffs still cannot compensate for the reduction in ablation due to debris-cover. In addition to cliff enhancement, a combination of reduced ablation and lower emergence velocities could be responsible for the debris-cover anomaly on debris-covered tongues.</p

Prevalence of impairments, disabilities, handicaps and quality of life in the general population: a review of recent literature

International audienc

Review article of the current state of glaciers in the tropical Andes: a multi-century perspective on glacier evolution and climate change

The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the LIA (mid 17th–early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 yr, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the computed global average. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decreasing from −0.2m w.e. in the period 1964–1975 to −0.76m w.e. in the period 1976–2010. In addition, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that as a percentage, this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades. Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia showed that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance variability at the interannual to decadal time scale. Precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, temperature increased at a significant rate of 0.10◦Cdecade−1 in the last 70 yr. The higher frequency of El Nin ̃o events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world

Corrigendum to Genome-wide analysis of over 106 000 individuals identifies 9 neuroticism-associated loci

Neuroticism is a personality trait of fundamental importance for psychological well-being and public health. It is strongly associated with major depressive disorder (MDD) and several other psychiatric conditions. Although neuroticism is heritable, attempts to identify the alleles involved in previous studies have been limited by relatively small sample sizes. Here we report a combined meta-analysis of genome-wide association study (GWAS) of neuroticism that includes 91 370 participants from the UK Biobank cohort, 6659 participants from the Generation Scotland: Scottish Family Health Study (GS:SFHS) and 8687 participants from a QIMR (Queensland Institute of Medical Research) Berghofer Medical Research Institute (QIMR) cohort. All participants were assessed using the same neuroticism instrument, the Eysenck Personality Questionnaire-Revised (EPQ-R-S) Short Form’s Neuroticism scale. We found a single-nucleotide polymorphism-based heritability estimate for neuroticism of ~15% (s.e.=0.7%). Meta-analysis identified nine novel loci associated with neuroticism. The strongest evidence for association was at a locus on chromosome 8 (P=1.5 × 10−15) spanning 4 Mb and containing at least 36 genes. Other associated loci included interesting candidate genes on chromosome 1 (GRIK3 (glutamate receptor ionotropic kainate 3)), chromosome 4 (KLHL2 (Kelch-like protein 2)), chromosome 17 (CRHR1 (corticotropin-releasing hormone receptor 1) and MAPT (microtubule-associated protein Tau)) and on chromosome 18 (CELF4 (CUGBP elav-like family member 4)). We found no evidence for genetic differences in the common allelic architecture of neuroticism by sex. By comparing our findings with those of the Psychiatric Genetics Consortia, we identified a strong genetic correlation between neuroticism and MDD and a less strong but significant genetic correlation with schizophrenia, although not with bipolar disorder. Polygenic risk scores derived from the primary UK Biobank sample captured ~1% of the variance in neuroticism in the GS:SFHS and QIMR samples, although most of the genome-wide significant alleles identified within a UK Biobank-only GWAS of neuroticism were not independently replicated within these cohorts. The identification of nine novel neuroticism-associated loci will drive forward future work on the neurobiology of neuroticism and related phenotypes