A tool for assessing error in digital elevation models from a user’s perspective

A Digital Elevation Model (DEM) is a representation of geographic reality. The elevations recorded within DEMs have been shown to contain errors pertaining to sampling, measurement and interpolation (Fisher, 1998). Even a small amount of elevation error can greatly affect derivative products (Holmes et al., 2000). This can potentially have a significant impact on the application of DEMs in Geographical Information Systems (GIS) where first and second order derivatives are considered

Multi-Scale Entropy Analysis as a Method for Time-Series Analysis of Climate Data

Evidence is mounting that the temporal dynamics of the climate system are changing at the same time as the average global temperature is increasing due to multiple climate forcings. A large number of extreme weather events such as prolonged cold spells, heatwaves, droughts and floods have been recorded around the world in the past 10 years. Such changes in the temporal scaling behaviour of climate time-series data can be difficult to detect. While there are easy and direct ways of analysing climate data by calculating the means and variances for different levels of temporal aggregation, these methods can miss more subtle changes in their dynamics. This paper describes multi-scale entropy (MSE) analysis as a tool to study climate time-series data and to identify temporal scales of variability and their change over time in climate time-series. MSE estimates the sample entropy of the time-series after coarse-graining at different temporal scales. An application of MSE to Central European, variance-adjusted, mean monthly air temperature anomalies (CRUTEM4v) is provided. The results show that the temporal scales of the current climate (1960–2014) are different from the long-term average (1850–1960). For temporal scale factors longer than 12 months, the sample entropy increased markedly compared to the long-term record. Such an increase can be explained by systems theory with greater complexity in the regional temperature data. From 1961 the patterns of monthly air temperatures are less regular at time-scales greater than 12 months than in the earlier time period. This finding suggests that, at these inter-annual time scales, the temperature variability has become less predictable than in the past. It is possible that climate system feedbacks are expressed in altered temporal scales of the European temperature time-series data. A comparison with the variance and Shannon entropy shows that MSE analysis can provide additional information on the statistical properties of climate time-series data that can go undetected using traditional method

IT security certifications : stakeholder evaluation and selection

Information technology (IT) security certifications have proliferated in recent years. However they differ in regards to stakeholder considerations of credibility, accessibility and relevance. Key stakeholders with an interest in selecting an IT security certification (IT security professionals, employers, governments and higher education institutes) lack a systematic approach for differentiating between candidate certifications and selecting the &ldquo;best&rdquo; certification to satisfy requirements. The paper focuses on reporting a confirmatory focus group from a recent research project. It provides a framework for supporting stakeholder evaluation and selection of IT security certifications and discusses key implications for the IT security industry, IT security certifications, and the higher education sector.<br /

Abelian varieties isogenous to a power of an elliptic curve

Let $E$ be an elliptic curve over a field $k$. Let $R:= \text{End}\, E$. There is a functor $\mathscr{H}\!\!\mathit{om}_R(-,E)$ from the category of finitely presented torsion-free left $R$-modules to the category of abelian varieties isogenous to a power of $E$, and a functor $\text{Hom}(-,E)$ in the opposite direction. We prove necessary and sufficient conditions on $E$ for these functors to be equivalences of categories.Comment: 21 pages, comments welcom

Keep Your Stats in the Cloud! Evaluating the Use of Google Sheets to Teach Quantitative Methods

Teaching quantitative methods at the undergraduate level is a difficult yet rewarding endeavor due to the challenges instructors face in presenting the material. One way to bolster student learning is through the use of statistical software packages. Google Sheets is a cloud-based spreadsheet program capable of many basic statistical procedures, which has yet to be evaluated for use in quantitative methods courses. This article contains pros and cons to using Google Sheets in the classroom and provides an evaluation of student attitudes toward using Google Sheets in an introductory quantitative methods class. The results suggest favorable student attitudes toward Google Sheets and which attitudes toward Google Sheets show a positive relationship with quantitative self-efficacy. Thus, based on the positive student attitudes and the unique features of Google Sheets, it is a viable program to use in introductory methods classes. However, due to limited functionality, Google Sheets may not be useful for more advanced courses. Future research may want to evaluate the use of third-party Google Sheets applications, which can increase functionality, and the use of Google Sheets in online classes

Atmospheric mercury and fine particulate matter in coastal New England : implications for mercury and trace element sources in the northeastern United States

This paper is not subject to U.S. copyright. The definitive version was published in Atmospheric Environment 79 (2013): 760–768, doi:10.1016/j.atmosenv.2013.07.031.Intensive sampling of ambient atmospheric fine particulate matter was conducted at Woods Hole, Massachusetts over a four-month period from 3 April to 29 July, 2008, in conjunction with year-long deployment of the USGS Mobile Mercury Lab. Results were obtained for trace elements in fine particulate matter concurrently with determination of ambient atmospheric mercury speciation and concentrations of ancillary gasses (SO2, NOx, and O3). For particulate matter, trace element enrichment factors greater than 10 relative to crustal background values were found for As, Bi, Cd, Cu, Hg, Pb, Sb, V, and Zn, indicating contribution of these elements by anthropogenic sources. For other elements, enrichments are consistent with natural marine (Na, Ca, Mg, Sr) or crustal (Ba, Ce, Co, Cs, Fe, Ga, La, Rb, Sc, Th, Ti, U, Y) sources, respectively. Positive matrix factorization was used together with concentration weighted air-mass back trajectories to better define element sources and their locations. Our analysis, based on events exhibiting the 10% highest PM2.5 contributions for each source category, identifies coal-fired power stations concentrated in the U.S. Ohio Valley, metal smelting in eastern Canada, and marine and crustal sources showing surprisingly similar back trajectories, at times each sampling Atlantic coastal airsheds. This pattern is consistent with contribution of Saharan dust by a summer maximum at the latitude of Florida and northward transport up the Atlantic Coast by clockwise circulation of the summer Bermuda High. Results for mercury speciation show diurnal production of RGM by photochemical oxidation of Hg° in a marine environment, and periodic traverse of the study area by correlated RGM-SO2(NOx) plumes, indicative of coal combustion sources.We acknowledge support of the USGS Toxic Substances Hydrology Program, the USGS Energy Resources Program, the National Science Foundation Small Grants for Exploratory Research Program, and for initial support, the USGS Mendenhall Postdoctoral Program

Structural properties of mobile armors formed at different flow strengths in gravel-bed rivers

Differences in the structure of mobile armors formed at three different flow strengths have been investigated in a laboratory flume. The temporal evolution of the bed surfaces and the properties of the final beds were compared using metrics of surface grain size, microtopography, and bed organization at both grain and mesoscales. Measurements of the bed condition were obtained on nine occasions during each experiment to describe the temporal evolution of the beds. Structured mobile armors formed quickly in each experiment. At the grain scale (1–45 mm; 9 ≤ Ds50 ≤ 17 mm where Ds50 is the median surface particle size), surface complexity decreased and bed roughness increased in response to surface coarsening and the development of the mobile armor. Particles comprising the armor also became flow aligned and developed imbrication. At a larger scale (100–200 mm), the surface developed a mesoscale topography through the development of bed patches with lower and higher elevations. Metrics of mobile armor structure showed remarkable consistency over prolonged periods of near-constant transport, demonstrating for the first time that actively transporting surfaces maintain an equilibrium bed structure. Bed structuring was least developed in the experiments conducted at the lowest flow strength. However, little difference was observed in the structural metrics of the mobile armors generated at higher flows. Although the range of transport rates studied was limited, the results suggest that the structure of mobile armors is insensitive to the formative transport rate except when rates are low (τ* ≈ 0.03 where τ* is the dimensionless shear stress)

Transcriptomic Shock Generates Evolutionary Novelty in a Newly Formed, Natural Allopolyploid Plant

SummaryNew hybrid species might be expected to show patterns of gene expression intermediate to those shown by parental species [1, 2]. “Transcriptomic shock” may also occur, in which gene expression is disrupted; this may be further modified by whole genome duplication (causing allopolyploidy) [3–16]. “Shock” can include instantaneous partitioning of gene expression between parental copies of genes among tissues [16–19]. These effects have not previously been studied at a population level in a natural allopolyploid plant species. Here, we survey tissue-specific expression of 144 duplicated gene pairs derived from different parental species (homeologs) in two natural populations of 40-generation-old allotetraploid Tragopogon miscellus (Asteraceae) plants. We compare these results with patterns of allelic expression in both in vitro “hybrids” and hand-crossed F1 hybrids between the parental diploids T. dubius and T. pratensis, and with patterns of homeolog expression in synthetic (S1) allotetraploids. Partitioning of expression was frequent in natural allopolyploids, but F1 hybrids and S1 allopolyploids showed less partitioning of expression than the natural allopolyploids and the in vitro “hybrids” of diploid parents. Our results suggest that regulation of gene expression is relaxed in a concerted manner upon hybridization, and new patterns of partitioned expression subsequently emerge over the generations following allopolyploidization

Specialist intellectual disability liaison nurses in general hospitals in England: cohort study using a large mortality dataset

Objective: Intellectual disability liaison nurses in general hospitals could enhance access to high-quality, adapted healthcare and improve outcomes. We aimed to explore associations between the input of intellectual disability liaison nurses and the quality of care in people with intellectual disability who are admitted to hospital. Design: Retrospective analysis of a national dataset of mortality reviews. Setting: General hospitals in England. Participants: 4742 adults with intellectual disability who died in hospital between 2016 and 2021 and whose deaths were reviewed as part of the Learning from Lives and Deaths mortality review programme. Outcome measures: We used logistic regression to compare the sociodemographic and clinical characteristics of those who did, and did not, receive input from an intellectual disability liaison nurse. We explored associations between liaison nurse input, care processes and overall quality of care. Results: One-third of people with intellectual disability who died in hospital in England between 2016 and 2021 had input from an intellectual disability liaison nurse. Intellectual disability liaison nurse input was not evenly distributed across England and was more common in those who died of cancer. Having an intellectual disability liaison nurse involved in an individual’s care was associated with increased likelihood of reasonable adjustments being made to care (adjusted OR (aOR) 1.95, 95% CI 1.63 to 2.32) and of best practice being identified (aOR 1.37, 95% CI 1.17 to 1.60) but was not associated with a rating of overall quality of care received (aOR 0.94, 95% CI 0.78 to 1.12). Conclusions: Intellectual disability liaison nurses see only a minority of people with intellectual disability who are admitted to hospital in England. Increasing the availability of intellectual disability liaison nurses could improve care for this disadvantaged group

Structural properties of mobile armors formed at different flow strengths in gravel-bed rivers

©2016. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Differences in the structure of mobile armors formed at three different flow strengths have been investigated in a laboratory flume. The temporal evolution of the bed surfaces and the properties of the final beds were compared using metrics of surface grain size, microtopography, and bed organization at both grain and mesoscales. Measurements of the bed condition were obtained on nine occasions during each experiment to describe the temporal evolution of the beds. Structured mobile armors formed quickly in each experiment. At the grain scale (1–45 mm; 9 ≤ Ds50 ≤ 17 mm where Ds50 is the median surface particle size), surface complexity decreased and bed roughness increased in response to surface coarsening and the development of the mobile armor. Particles comprising the armor also became flow aligned and developed imbrication. At a larger scale (100–200 mm), the surface developed a mesoscale topography through the development of bed patches with lower and higher elevations. Metrics of mobile armor structure showed remarkable consistency over prolonged periods of near-constant transport, demonstrating for the first time that actively transporting surfaces maintain an equilibrium bed structure. Bed structuring was least developed in the experiments conducted at the lowest flow strength. However, little difference was observed in the structural metrics of the mobile armors generated at higher flows. Although the range of transport rates studied was limited, the results suggest that the structure of mobile armors is insensitive to the formative transport rate except when rates are low (τ* ≈ 0.03 where τ* is the dimensionless shear stress)