Methylmercury Production in Denitrifying Woodchip Bioreactors

Several operational woodchip bioreactors were installed at the outlets of agricultural drainage systems located in east central Illinois. The potential for monomethylmercury (MMHg) production and export in these bioreactors was investigated from summer 2008 to summer 2010. The basic approach was to compare the chemistry of simultaneously-collected bioreactor inlet and outlet water samples in order to assess the extent of nitrate depletion, consumption of sulfate, and production of MMHg, plus other low-charge mercury species (LCHg). In making such a comparison, we implicitly assume that the reactor is near steady state, which is a reasonable approximation given hydraulic residence times on the order of hours. All mercury (Hg) speciation measurements were made using a first-generation mercury thiourea complex ion chromatography system for Hg speciation analysis, which reliably separates MMHg and HgII (mercuric mercury), but combines MMHg and a newly-discovered, unidentified Hg species of low charge (LCHg). Due to this analytical artifact, the results reported here constitute an upper bound on true Hg methylation. In no season was MMHg ever detected in inlet samples at concentrations at much above the detection limit of ~0.1 ng/L. However, levels of MMHg+LCHg over 2 ng/L were observed in the outlets during warm seasons when nitrate had become depleted within the bioreactor. Sulfate depletion was also observed in most samples with elevated [MMHg+LCHg]. The combination of sulfate depletion and MMHg production is consistent with nitrate inhibition of iron and sulfate reduction and with MMHg concentrations observed in other highly anaerobic environments, e.g., lake hypolimnia and wetland porewaters. The maximum [MMHg+LCHg] observed in any given bioreactor followed an inverse function of the bioreactor loading density, i.e., the ratio of the area drained to the area of the bioreactor pit. The function has a form similar to that observed for bioreactor denitrification efficacy and suggests that optimal bioreactor designs that permit substantial denitrification while minimizing Hg methylation are feasible. Finally, extremely high MMHg+LCHg levels were observed when stagnant water conditions occurred within the bioreactors. Thus, it is recommended that bioreactors not be built with bottom depresssional areas where stagnant water can reside, in order to avoid developing anoxic conditions where methylation occurs. For the same reasons, bioreactors should not be used simultaneously with controlled drainage (water table management) if restricting the drainage results in keeping the bioreactors flooded for long periods of time.Illinois Sustainable Technology Center (Grant No. HWR09215)Ope

I\u27ve Got The Blue Ridge Blues : Song

https://digitalcommons.library.umaine.edu/mmb-vp/1714/thumbnail.jp

Correlated X-ray and Optical Variability in Mkn 509

We present results of a 3 year monitoring campaign of the Seyfert 1 galaxy Markarian 509, using X-ray data from the Rossi X-ray Timing Explorer (RXTE) and optical data taken by the SMARTS consortium. Both light curves show significant variations, and are strongly correlated with the optical flux leading the X-ray flux by 15 days. The X-ray power spectrum shows a steep high-frequency slope of -2.0, breaking to a slope of -1.0 at at timescale of 34 days. The lag from optical to X-ray emission is most likely caused by variations in the accretion disk propagating inward.Comment: 13 pages, 3 figures. Accepted for publication in the Astrophysical Journa

The relevance of smallholder farming to African agricultural growth and development

Farms less than two hectares constitute most farm holdings in Africa. Most of these farms are operated by rural smallholder farmers who are dependent on agriculture for their economic livelihoods. However, they are constrained by lack of capital assets that would enable them to increase agricultural productivity, food security and income. Despite these challenges, smallholders contribute significantly to the rural economy, and play a significant role in natural resource conservation. Therefore, they represent a critical population to include in poverty reduction efforts. Recent initiatives by African leaders aim to increase public expenditures on agriculture in order to spur economic development, position smallholders to play a significant role in regional growth. To understand the relevance of smallholder farming to Africa’s development agenda, this paper reviews the body of knowledge on smallholder farmers, the constraints and opportunities they face, and their use of practices which embody the tenets of ecological and climate-smart agriculture despite little public investment in this area. This paper recognizes the role of smallholder farmers and concludes that smallholder agriculture will be a driver of economic growth and development in Africa. In order to achieve this, adequate investment should be focused on eliminating the challenges faced by smallholder farmers.Keywords: Smallholder farmers, Sub-Saharan Africa, agricultural development, climate-smart agriculture, green agricultur

A geometric proof of the Kochen-Specker no-go theorem

We give a short geometric proof of the Kochen-Specker no-go theorem for non-contextual hidden variables models. Note added to this version: I understand from Jan-Aake Larsson that the construction we give here actually contains the original Kochen-Specker construction as well as many others (Bell, Conway and Kochen, Schuette, perhaps also Peres).Comment: This paper appeared some years ago, before the author was aware of quant-ph. It is relevant to recent developments concerning Kochen-Specker theorem

I\u27ve Got the Blue Ridge Blues

Illustration of pine trees and flowers on hillside; Blue sky in backgroundhttps://scholarsjunction.msstate.edu/cht-sheet-music/7512/thumbnail.jp

Functional plasticity in the type IV secretion system of Helicobacter pylori.

Helicobacter pylori causes clinical disease primarily in those individuals infected with a strain that carries the cytotoxin associated gene pathogenicity island (cagPAI). The cagPAI encodes a type IV secretion system (T4SS) that injects the CagA oncoprotein into epithelial cells and is required for induction of the pro-inflammatory cytokine, interleukin-8 (IL-8). CagY is an essential component of the H. pylori T4SS that has an unusual sequence structure, in which an extraordinary number of direct DNA repeats is predicted to cause rearrangements that invariably yield in-frame insertions or deletions. Here we demonstrate in murine and non-human primate models that immune-driven host selection of rearrangements in CagY is sufficient to cause gain or loss of function in the H. pylori T4SS. We propose that CagY functions as a sort of molecular switch or perhaps a rheostat that alters the function of the T4SS and "tunes" the host inflammatory response so as to maximize persistent infection

Testing the impact of an educational intervention designed to promote ocular health among people with age-related macular degeneration

Research has shown that individuals affected by age-related macular degeneration (AMD) do not always consume foods or supplements known to be beneficial for ocular health. This study tested the effectiveness of an educational intervention designed to promote healthy eating and nutritional supplementation in this group. A total of 100 individuals with AMD completed baseline measures of several variables: confidence that diet affects AMD, motivation to engage in health-protective behaviours, knowledge about which nutrients are beneficial, and intake of kale, spinach, and eggs. Participants were allocated to either intervention or control conditions. Intervention participants received a leaflet and prompt card that contained advice regarding dietary modification and supplementation. Control participants received a leaflet created by the Royal College of Optometrists. A follow-up questionnaire, measuring the same variables assessed at baseline, was administered 2 weeks later. At follow-up, significant condition × time interactions were found for confidence that diet affects AMD (F(1, 92) = 4.54, p < .05), motivation to talk to an eye professional about supplementation (F(1, 92) = 4.53, p = .036), motivation to eat eggs (F(1, 92) = 12.67, p = .001), and egg intake (F(1, 92) = 11.97, p = .001). In each case, intervention participants scored higher than control participants. Receiving an educational intervention increased participants’ confidence that diet affects AMD, motivation to engage in health-protective behaviours, and egg intake. This intervention could be easily incorporated into current clinical practice delivered by either optometrists or ophthalmologists

Dissociation of the diurnal variation of aldosterone and cortisol in anephric subjects

Dissociation of the diurnal variation of aldosterone and cortisol in anephric subjects. Diurnal variation of plasma aldosterone and cortisol concentration in man was studied in 13 anephric subjects and 7 normal subjects. All subjects were ambulatory and active throughout the study except during an 8-hour sleep period. Six anephric subjects received Kayexalate® (sodium polystyrene sulfonate) during the studies to prevent potassium accumulation and increase in plasma potassium concentration. Diurnal variation of plasma aldosterone concentration with peak and nadir concentrations at 12:00 noon and 12:00 midnight respectively was demonstrated in the studies on normal subjects. Changes in plasma aldosterone concentration were not significantly correlated with changes in plasma cortisol concentration but were highly correlated with changes in PRA (P < 0.001). There was a highly significant correlation between plasma aldosterone and potassium concentration in the anephric subjects studied without Kayexalate® administration (P < 0.001). In the anephric subjects who received Kayexalate®, plasma aldosterone and potassium concentration remained stable, and no correlation could be demonstrated. No diurnal variation of plasma aldosterone concentration could be demonstrated in either group of anephric subjects, whereas plasma cortisol concentration varied as in the studies on normal subjects. Conclusion. Diurnal variation of plasma aldosterone concentration is dependent on continued stimulation by the renin-angiotensin system. Loss of this stimulation has no demonstrable effect on the diurnal variation of plasma cortisol concentration.Dissociation des variations nycthémérales de l'aldostérone et du cortisol chez les sujets anéphriques. Les variations nycthémérales de l'aldostérone et du cortisol plasmatiques chez l'homme ont été étudiées chez 13 sujets anéphriques et 7 sujets normaux. Tous les sujets étaient ambulatoires excepté pendant une période de sommeil de 8 heures. Six sujets anéphriques receivaient du Kayexalate® (sodium polystyrene sulfonate) afin d'empêcher une accumulation de potassium et une augmentation de la kaliémie. Des variations nycthémérales de l'aldostéronémie avec un pic et un nadir à midi et minuit, respectivement, ont été observées chez les sujets normaux. Les modifications de l'aldostéronémie ne sont pas significativement corrélées avec les modifications du cortisol plasmatique mais très corrélées avec celles de PRA (P < 0,001). Il existe une corrélation très significative entre l'aldostéronémie et la kaliémie chez les sujets anéphriques étudiés en dehors de l'administration de Kayexalate (P < 0,001). Chez les sujets anéphriques recevant du Kayexalate l'aldostéronémie et la kaliémie sont stables et aucune corrélation n'est obtenue. Aucune variation nycthémérale de l'aldostéronémie n'a été observé dans les groupes de sujets anéphriques alors que la concentration de cortisol plasmatique varie comme chez les sujets normaux. Il peut être conclu de ces études que les variations nycthémérales de l'aldostéronémie dépendent de la stimulation par le système rénine-angiotensine. La perte de cette stimulation n'a pas d'effet sur la cortisolémie

Further Evaluation of the Associations Between Psychopathic Traits and Symptoms of PTSD and Depression in a Nonclinical Sample

Examining psychopathic traits at the factor or facet level has revealed that various aspects of psychopathy may be differentially related, even in opposing directions, to important outcomes (e.g., intelligence, emotion regulation). Empirical work on relations between psychopathy and internalizing disorders, such as posttraumatic stress disorder (PTSD) and depression, has provided evidence for a positive association with antisocial traits. However, findings for the affective domain have been more equivocal. The current study (N = 732) sought to replicate past findings of the positive association of antisocial psychopathic traits with higher levels of PTSD and depressive symptoms, and to further explore associations between affective traits of psychopathy and these disorders using two measures of psychopathy. Results confirmed prior findings of a positive correlation between antisocial features and self-reported PTSD/Depression symptom severity, but they did not provide evidence for any association with affective traits. Future research using longitudinal designs is needed to begin establishing temporal ordering of the psychopathy–internalizing relationship