Evaluating the association between extreme heat and mortality in urban Southwestern Ontario using different temperature data sources

Urban areas have complex thermal distribution. We examined the association between extreme temperature and mortality in urban Ontario, using two temperature data sources: high-resolution and weather station data. We used distributed lag non-linear Poisson models to examine census division-specific temperature–mortality associations between May and September 2005–2012. We used random-effect multivariate meta-analysis to pool results, adjusted for air pollution and temporal trends, and presented risks at the 99th percentile compared to minimum mortality temperature. As additional analyses, we varied knots, examined associations using different temperature metrics (humidex and minimum temperature), and explored relationships using different referent values (most frequent temperature, 75th percentile of temperature distribution). Weather stations yielded lower temperatures across study months. U-shaped associations between temperature and mortality were observed using both high-resolution and weather station data. Temperature–mortality relationships were not statistically significant; however, weather stations yielded estimates with wider confidence intervals. Similar findings were noted in additional analyses. In urban environmental health studies, high-resolution temperature data is ideal where station observations do not fully capture population exposure or where the magnitude of exposure at a local level is important. If focused upon temperature–mortality associations using time series, either source produces similar temperature–mortality relationships

Perfluoroalkyl and Polyfluoroalkyl Substances in the Environment: Terminology, Classification, and Origins

The primary aim of this article is to provide an overview of perfluoroalkyl and polyfluoroalkyl substances (PFASs) detected in the environment, wildlife, and humans, and recommend clear, specific, and descriptive terminology, names, and acronyms for PFASs. The overarching objective is to unify and harmonize communication on PFASs by offering terminology for use by the global scientific, regulatory, and industrial communities. A particular emphasis is placed on long-chain perfluoroalkyl acids, substances related to the long-chain perfluoroalkyl acids, and substances intended as alternatives to the use of the long-chain perfluoroalkyl acids or their precursors. First, we define PFASs, classify them into various families, and recommend a pragmatic set of common names and acronyms for both the families and their individual members. Terminology related to fluorinated polymers is an important aspect of our classification. Second, we provide a brief description of the 2 main production processes, electrochemical fluorination and telomerization, used for introducing perfluoroalkyl moieties into organic compounds, and we specify the types of byproducts (isomers and homologues) likely to arise in these processes. Third, we show how the principal families of PFASs are interrelated as industrial, environmental, or metabolic precursors or transformation products of one another. We pay particular attention to those PFASs that have the potential to be converted, by abiotic or biotic environmental processes or by human metabolism, into long-chain perfluoroalkyl carboxylic or sulfonic acids, which are currently the focus of regulatory action. The Supplemental Data lists 42 families and subfamilies of PFASs and 268 selected individual compounds, providing recommended names and acronyms, and structural formulas, as well as Chemical Abstracts Service registry numbers. Integr Environ Assess Manag 2011;7:513–541. © 2011 SETA

Arguing for computer science in the school curriculum

Computer science has been a discipline for some years, and its position in the school curriculum has been contested differently in several countries. This paper looks at its role in three countries to illustrate these differences. A reconsideration of computer science as a separate subject both in primary and secondary education is suggested. At EDUsummIT 2015 it was argued that the major rationales for including computer science as a subject in the K-12 curriculum are economic, social and cultural. The paper explores these three rationales and also a beneficence matrix to assist curriculum designers. It also argues computer science is rapidly becoming critical for generating new knowledge, and should be taught as a distinct subject or content area, especially in secondary schools. The paper concludes by looking at some of the key questions to be considered when implementing computer science in the school curriculum, and at ways its role might change in the future

Pushing the Geographic Envelope: How Far do we go with Warm Season Crops?

With rising input costs and unstable commodity prices, growers are constantly seeking new and innovative ways to make their farms more profitable. Over the past several years, growers have been experimenting with non-traditional crops as a way to improve their bottom line. Gone are the days of the traditional cereal and oilseed rotation across our landscape. Today many growers in Southern Manitoba are growing significant acres of warm season crops such as grain corn, sunflowers, edible beans and soybeans. With the potential for increased revenue from these crops there also comes considerably more risk to growing these warm season crops versus more traditional ones. Warm season crops have, and will, continue to be profitable when grown under the right conditions. However, many growers are trying to raise these crops in areas generally considered to be "fringe" areas not suitable for growing warm season crops for many reasons. Even with advancements in the genetics of these warm season crops, the summer of 2004 was a cruel reminder that you still need the heat. Our experiences from 2004 also make us ask the question of how far into these non-traditional geographies do we push these crops before we realize that they were maybe just not meant to be grown there? The following paper will examine management variables that a first time producer needs to look at before attempting to grow a warm season crop in a non-traditional area. We will examine specifically the influence of soil type and drainage, tolerance to excess and lack of moisture, frost-free period, available heat units, photoperiod and topography. In general, most crops will grow well on most types of soils, anything from a sandy loam to a clay loam soil so long as the particular soil type has good structure, good internal drainage and other fertility attributes like high CEC and organic matter. A well-drained soil is one that can hold the adequate amount of moisture a crop requires and also has the ability to shed the excess moisture before it becomes a stress on the crop. Unfortunately we don't live in a perfect world and quite often end up dealing with periods of excess or lack of moisture. Tolerance and adaptation of a crop to excess moisture is plant species dependant. Most annual crops, especially cereal grains, can tolerate 3 to 7 days of water stress depending on the soil type, plant species and soil temperature. For example, corn which is fairly tolerant to excess moisture in and of itself can actually only tolerate no more than a 24 hour period of excess moisture stress when the soil temperature is 24 C or above. Plants adapt to water stress in the short term by slowing growth of the shoot and reducing respiration rates to conserve oxygen that is needed by the roots. Supplemental nitrogen fertilizer can sometimes benefit an oxygen-deprived crop by supplying the oxygen gas that is needed but this is only a temporary fix. Longer-term solutions require the implementation of systems like tile and surface drainage. When excess moisture is not a concern as much as a lack of moisture, tolerance again is plant species dependant. Warm season crops like corn and sunflowers have generally deeper root systems that explore more of the soil profile and can access subsoil moisture better than pulses like soybeans and edible beans. They are more shallow rooted and grow more lateral root growth therefore exploring more of the A horizon that is subject to drying out quicker. Tolerance of excess moisture from best to worst can be described as corn>soybeans>sunflowers>edible beans, whereas tolerance to drier conditions can be described as sunflowers>corn>edible beans>soybeans. Frost-free period can be defined as the number of days between the last spring frost and the first fall frost. This range determines the length of growing season and the types of crops that can be grown to maturity in those areas. Every crop requires a certain number of frost-free days. With regards to warm season crops, grain corn generally requires 110 to 120 days, sunflowers require 90 to 120 days, soybeans require 108 to 125 days and edible beans require 99 to 114 frost-free days to mature. Each of these crops also varies in their tolerance to frost. Looking at these crops from most tolerant to least tolerant would look something like this: sunflower>corn>soybeans>edible beans. Grain corn can be damaged by frost up to the 5 leaf stage but will still re-grow new leaves because the plant's growing point remains under the soil surface until that critical point. In most cases pulses are the weakest when it comes to frost. Bot

A K-6 computational thinking curriculum framework:Implications for teacher knowledge

Adding computer science as a separate school subject to the core K-6 curriculum is a complex issue with educational challenges. The authors herein address two of these challenges: (1) the design of the curriculum based on a generic computational thinking framework, and (2) the knowledge teachers need to teach the curriculum. The first issue is discussed within a perspective of designing an authentic computational thinking curriculum with a focus on real-world problems. The second issue is addressed within the framework of technological pedagogical content knowledge explicating in detail the body of knowledge that teachers need to have to be able to teach computational thinking in a K-6 environment. An example of how these ideas can be applied in practice is also given. While it is recognized there is a lack of adequate empirical evidence in terms of the effectiveness of the frameworks proposed herein, it is expected that our knowledge and research base will dramatically increase over the next several years, as more countries around the world add computer science as a separate school subject to their K-6 curriculum

Isolation of malignant B cells from patients with chronic lymphocytic leukemia (CLL) for analysis of cell proliferation:validation of a simplified method suitable for multi-center clinical studies

BACKGROUND: Heavy water ((2)H(2)O) labelling of DNA enables the measurement of low-level cell proliferation in vivo, using gas chromatography/pyrolysis isotope ratio mass spectrometry (GC/P/IRMS), but the methodology has been too complex for widespread use. Here, we report a simplified method for measuring proliferation of malignant B cells in patients with chronic lymphocytic leukemia (CLL). DESIGN AND METHODS: Patients were labelled with (2)H(2)O for 6 weeks; blood samples were obtained at 0, 3, and 6 weeks during (2)H(2)O labelling and 9, 12, and 16 weeks thereafter. Bone marrow was sampled at week 6. Phlebotomy was performed at multiple, non-research clinical sites. CLL cells were isolated in a central laboratory, using a novel RosetteSep™-based method; DNA labelling was analysed by GC/P/IRMS. RESULTS: In 26 of 29 patients, CLL cell isolation resulted in ≥ 95% purity for malignant CD5+ B cells; in one patient, malignant cells expressed marginal levels of CD5, and in two others, further sorting of CD5hi malignant cells was required. Cell yields correlated with white blood cell counts and exceeded GC/P/IRMS requirements (≈ 10(7) cells) > 98% of the time; high-quality DNA labelling data were obtained. RosetteSep isolation achieved adequate CLL cell purity from bone marrow in only 64% of samples, but greatly reduced subsequent sort time for impure samples. CONCLUSION: This method enables clinical studies of CLL cell proliferation outside of research settings, using a shorter (2)H(2)O intake protocol, a minimal sampling protocol, and centralised sample processing. The CLL cell isolation protocol may also prove useful in other applications. (clinicaltrials.gov identifier: NCT00481858

Measurement of reverse cholesterol transport pathways in humans: in vivo rates of free cholesterol efflux, esterification, and excretion.

BackgroundReverse cholesterol transport from peripheral tissues is considered the principal atheroprotective mechanism of high-density lipoprotein, but quantifying reverse cholesterol transport in humans in vivo remains a challenge. We describe here a method for measuring flux of cholesterol though 3 primary components of the reverse cholesterol transport pathway in vivo in humans: tissue free cholesterol (FC) efflux, esterification of FC in plasma, and fecal sterol excretion of plasma-derived FC.Methods and resultsA constant infusion of [2,3-(13)C(2)]-cholesterol was administered to healthy volunteers. Three-compartment SAAM II (Simulation, Analysis, and Modeling software; SAAM Institute, University of Washington, WA) fits were applied to plasma FC, red blood cell FC, and plasma cholesterol ester (13)C-enrichment profiles. Fecal sterol excretion of plasma-derived FC was quantified from fractional recovery of intravenous [2,3-(13)C(2)]-cholesterol in feces over 7 days. We examined the key assumptions of the method and evaluated the optimal clinical protocol and approach to data analysis and modeling. A total of 17 subjects from 2 study sites (n=12 from first site, age 21 to 75 years, 2 women; n=5 from second site, age 18 to 70 years, 2 women) were studied. Tissue FC efflux was 3.79±0.88 mg/kg per hour (mean ± standard deviation), or ≍8 g/d. Red blood cell-derived flux into plasma FC was 3.38±1.10 mg/kg per hour. Esterification of plasma FC was ≍28% of tissue FC efflux (1.10±0.38 mg/kg per hour). Recoveries were 7% and 12% of administered [2,3-(13)C(2)]-cholesterol in fecal bile acids and neutral sterols, respectively.ConclusionsThree components of systemic reverse cholesterol transport can be quantified, allowing dissection of this important function of high-density lipoprotein in vivo. Effects of lipoproteins, genetic mutations, lifestyle changes, and drugs on these components can be assessed in humans. (J Am Heart Assoc. 2012;1:e001826 doi: 10.1161/JAHA.112.001826.)