An investigation into the link between vitamin D status, erectile dysfunction and cardiovascular risk factors in ageing men in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Palmerston North, New Zealand

Background Cardiovascular disease (CVD) is the leading cause of death worldwide, particularly amongst ageing males. Prevention and/or early identification and effective intervention are essential in the fight against CVD. Erectile dysfunction (ED) is a prevalent and multi-factorial condition that is now accepted to be an early marker of subclinical CVD: the common denominator is endothelial dysfunction. Both the enzymatic capability for bioactivation of vitamin D and the vitamin D receptor (VDR) are expressed in endothelial cells and vitamin D may play a role in endothelial function. Vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) concentrations ˂50 nmol/L) is a worldwide pandemic and serum 25(OH)D levels ˂75 nmol/L may result in metabolic and vascular deterioration leading to endothelial dysfunction, ED and CVD. Assessment of erectile function can be used to identify otherwise asymptomatic men at high risk of developing clinical CVD, at a time when effective intervention may prevent, delay or reverse its progression. Vitamin D status may be associated with ED and CVD risk and could help improve erectile function and vascular health. Objectives The aim of this research was to investigate the postulated link between vitamin D status, ED, and CVD risk factors. The objectives were (1) to assess the prevalence of ED (using the 5-item International Index of Erectile Function (IIEF-5)) and its associated sociodemographic, lifestyle, and medical correlates in New Zealand (NZ) men aged 40-70 years; (2) to investigate the relationship between vitamin D status (serum 25(OH)D concentration), ED and other CVD risk factors in men aged 40-70 years living in the Manawatu region of NZ; and (3) to examine the impact of common VDR gene (VDR) polymorphisms on this relationship. Method Two thousand men aged 40-70 years were randomly selected from the NZ Electoral Roll and sent an anonymous postal survey designed to assess the prevalence of ED and its sociodemographic, lifestyle, and medical risk factors. Six hundred men aged 40-70 years living in the Manawatu region were randomly selected from the NZ Electoral Roll and invited to participate in an observational study designed to provide a comprehensive health profile of self-reported healthy men and investigate the relationship between vitamin D status, ED, and a range of CVD risk factors. Eligible participants (n=100) completed a comprehensive health assessment including a medical history, anthropometric and cardiovascular assessment, fasting blood sample, computer-based questionnaire, a submaximal fitness test and a handgrip iv strength test. Blood samples were assessed for four common VDR polymorphisms (rs11568820 (Cdx2), rs10735810 (FokI), rs1544410 (BsmI) and rs731236 (TaqI)) using polymerase chain reaction-high resolution amplicon melt (PCR-HRM) analysis. Results The survey showed 38.4% of respondents presented with ED (IIEF-5 ≤21). Older age, non-European ethnicity and current smoking were significant independent predictors of an increased risk of ED, while a high household income and regular vigorous physical activity (PA) were deemed protective. The observational study showed 30 men presented with ED and a further 37 men had <75 nmol/L 25(OH)D. There was a weak positive correlation between IIEF-5 scores and 25(OH)D levels (rs=0.238, p=0.017). Men with <75 nmol/L had lower IIEF-5 scores compared to men with ≥75 nmol/L 25(OH)D (22(7) vs. 24(3), p=0.001). Men with ED had lower 25(OH)D levels compared to men without ED (74.5(34) vs. 84.5(24), p=0.062). Every 1 nmol/L of 25(OH)D predicted a 2% decrease in the age-adjusted risk of ED (age-adjusted OR=0.98 [0.96-1.00], p=0.046). The PCR-HRM analysis showed that the Cdx2, FokI and BsmI polymorphisms were all significantly associated with an adverse cardiovascular risk profile. The Cdx2 G allele was associated with lower IIEF-5 scores compared to the A allele (23(4) vs. 24(2), p=0.008) and the GA and GG genotypes were predictors of an increased age-adjusted risk of ED (age-adjusted OR=18.78 [1.98-178.60], p=0.011 and 8.53 [1.00-72.73], p=0.050 respectively). However, Cdx2 was not found to modify the age-adjusted association between 25(OH)D levels and ED (multi-adjusted OR=0.97 [0.95-1.00], p=0.032). Conclusions These results suggest that over a third of NZ men aged 40-70 years suffer from ED and it is associated with sociodemographic, lifestyle and medical factors simliar to CVD. Low serum 25(OH)D is associated with the presence and severity of ED in a self-reported healthy population. Common VDR polymorphisms are also associated with ED; however, they do not modify the association between serum 25(OH)D and ED. A randomised placebo-controlled human intervention trial is warranted to investigate whether improving vitamin D status in men with vitamin D deficiency and ED ameliorates symptoms and reduces the risk of CVD

Syria in crisis: the harrowing case of Aleppo

The city of Aleppo is a key battleground in the Syrian civil war and has seen intense fighting since 2012. On Tuesday morning, the city fell to government forces amidst claims of severe human rights abuses and deteriorating conditions on the ground. Throughout the conflict, the city has been split between two major warring factions: the pro-Assad forces, backed by Russia, Iran and other Shia groups, holding the western part of the city, and the Syrian rebel groups, backed by Turkey, Saudi Arabia and the United States, claiming the east. Other groups, including armed terrorist factions and Kurdish militias, are also involved in the conflict and maintain smaller territory throughout the city. Reports claim that the Kurds have been cooperating with the Assad regime to oust rebel groups from the city

Investigating Individual Differences in the Conceptual Change of Biology Misconceptions Using Computer-Based Explanation Tasks

The current study examined the effects of computer-based self-explanations (i.e., generated by the learner) and instructional explanations (i.e., provided to the learner) on undergraduate biology students’ revision of photosynthesis and respiration misconceptions. Individual differences, particularly students’ prior knowledge, significantly impact the effectiveness of instructional tasks. Oftentimes, an instructional task is effective only for learners at a particular prior knowledge level. Cognitive Load Theory suggests that too much or too little instructional support can overwhelm a learner’s working memory. When used for building knowledge, self-explanations and instructional explanations, like those employed in the current study, both interact with prior knowledge. Prior research has indicated that instructional explanations may only benefit students with low prior knowledge, and self-explanations may only benefit students with high prior knowledge. The current study addressed whether such effects extend to the use of explanation tasks to facilitate knowledge revision, in which existing misconceptions are revised. Four hundred and thirty eight undergraduate major and non-major biology students completed an online activity for course credit. Participants were randomly assigned to one of three conditions (self-explanation, instructional explanation, or no explanation) and then prompted with a set of photosynthesis questions, each of which was followed by their assigned instructional task and a cognitive load measure. One week later, participants returned to the activity to take a posttest. Results indicated students entered the activity with high rates of photosynthesis and respiration misconceptions. Further regression analyses indicated that only self-explanations, not instructional explanations, increased learning compared to no explanations. Trends in effect sizes suggest self-explanations only benefited students with sufficient prior knowledge. Higher cognitive load was associated with less learning in both explanation conditions, but not in the no explanation condition. The current results suggest that self-explanations may effectively promote knowledge revision, assuming students are familiar with the content, while instructional explanations may not foster knowledge revision in a computer-based setting. Implications for adaptive instruction that targets knowledge revision are addressed

Towards understanding the nature and diversity of small planets in the universe : discovery and initial characterization of Wolf 503 b and LP 791-18 d

Avec la découverte de milliers de nouvelles planètes au cours des vingt dernières années, une nouvelle population complexe de planètes plus petites que Neptune et plus grandes que la Terre a été découverte. Ces planètes se divisent en deux groupes : les plus grandes sub-Neptunes avec des atmosphères étendues dominées par H, et les plus petites super-Terres qui ont tout au plus des atmosphères minces. Cette division peut être expliquée par une variété de mécanismes, y compris la photoévaporation, la perte de masse alimentée par le noyau, et la formation de gaz pauvres et vides : la population de petites planètes est probablement façonnée par une combinaison de ces mécanismes qui peut dépendre du type stellaire. Dans ce travail, nous décrivons la découverte de deux nouvelles planètes qui sont bien adaptées à l'étude de la nature de la population des petites planètes : Wolf 503 b et LP 791-18 d. Wolf 503 b est une planète de $2.03^{+0.08}_{-0.07} R_{\oplus}$ orbitant autour de l'étoile brillante ($J=8.32$ mag), proche ($D=44.5$ pc) à mouvement propre élevé K3.5V Wolf 503 (EPIC 212779563). Nous confirmons que la signature du transit K2 est planétaire en utilisant à la fois des images d'archives et des images d'optique adaptative à haut contraste de l'observatoire Palomar. Son rayon place Wolf 503b directement entre les populations de super-Terre et de sub-Neptune, un rayon auquel les planètes sont rarement trouvées et la composition de masse attendue est ambiguë, et la luminosité de l'étoile hôte fait de Wolf 503b une cible de choix pour le suivi des vitesses radiales et la spectroscopie de transit. La deuxième planète que nous présentons est une planète de taille terrestre orbitant autour de la naine froide M6 LP 791-18. La nouvelle planète d rejoint un système bien aligné avec au moins deux autres planètes, la plus externe étant une sous-Neptune, offrant une occasion unique à ce jour d'étudier un système avec une planète de taille terrestre tempérée et une sous-Neptune qui a conservé son enveloppe gazeuse ou volatile. La découverte de LP 791-18d permet de mesurer la masse du système grâce aux variations du temps de transit, et nous trouvons une masse de ${9.3_{-1.4}^{+1.5}\,M_\oplus}$ pour la sub-Neptune LP 791-18c et une masse de ${0.8_{-0.4}^{+0.5}\,M_\oplus}$ pour l'exo-Terre LP 791-18d (${<2.3 M_{\oplus}}$ à 3${\sigma}$). La planète est également soumise à un fort réchauffement continu par les marées, ce qui peut entraîner une activité géologique et un dégazage volcanique. Pour l'avenir, LP 791-18d et Wolf 503b offrent des opportunités uniques d'étudier les origines et la conservation des atmosphères des petites planètes.With the discovery of thousands of new planets in the past twenty years, a new and complex population of planets has been discovered which are smaller than Neptune and larger than the Earth. These planets are split into two groups: the larger sub-Neptunes with extended H-dominated atmospheres, and the smaller super-Earths which have at most thin atmospheres. This division can be explained by a variety of mechanisms, including photoevaporation, core-powered mass-loss, and gas-poor and gas-empty formation: the small-planet population is likely shaped by a combination of these which may depend on stellar type. In this work we describe the discovery of two new planets which are well-suited to investigating the nature of the small planet population: Wolf 503b and LP 791-18d. Wolf 503 b is a $2.03^{+0.08}_{-0.07} R_{\oplus}$ planet orbiting the bright ($J=8.32$ mag), nearby ($D=44.5$ pc) high proper motion K3.5V star Wolf 503 (EPIC 212779563). We confirm that the K2 transit signature is planetary using both archival images and high-contrast adaptive optics images from the Palomar observatory. Its radius places Wolf 503 b directly between the populations of super-Earths and sub-Neptunes, a radius at which planets are rarely found and the expected bulk composition is ambiguous, and the brightness of the host star makes Wolf 503b a prime target for radial velocity follow-up and transit spectroscopy. The second planet we introduce is an Earth-sized planet orbiting the cool M6 dwarf LP 791-18. The new planet d joins a well-aligned system with at least two more planets, the outermost being a sub-Neptune, providing a to-date unique opportunity to investigate a system with a temperate Earth-sized planet and a sub-Neptune that retained its gas or volatile envelope. The discovery of LP 791-18d makes the system amenable to mass measurements via transit timing variations, and we find a mass of ${9.3_{-1.4}^{+1.5}\,M_\oplus}$ for the sub-Neptune LP 791-18c and a mass of ${0.8_{-0.4}^{+0.5}\,M_\oplus}$ for the exo-Earth LP 791-18d (${<2.3 M_{\oplus}}$ at 3${\sigma}$). The planet is also subject to strong continued tidal heating, which may result in geological activity and volcanic outgassing. Looking forward, LP 791-18d and Wolf 503b offer unique opportunities to study the origins and retention of small-planet atmospheres

Differences in power law growth over time and indicators of COVID-19 pandemic progression worldwide

Error analysis and data visualization of positive COVID-19 cases in 27 countries have been performed up to August 8, 2020. This survey generally observes a progression from early exponential growth transitioning to an intermediate power-law growth phase, as recently suggested by Ziff and Ziff. The occurrence of logistic growth after the power-law phase with lockdowns or social distancing may be described as an effect of avoidance. A visualization of the power-law growth exponent over short time windows is qualitatively similar to the Bhatia visualization for pandemic progression. Visualizations like these can indicate the onset of second waves and may influence social policy

Frontiers in microfluidics, a teaching resource review

This is a literature teaching resource review for biologically inspired microfluidics courses or exploring the diverse applications of microfluidics. The structure is around key papers and model organisms. While courses gradually change over time, a focus remains on understanding how microfluidics has developed as well as what it can and cannot do for researchers. As a primary starting point, we cover micro-fluid mechanics principles and microfabrication of devices. A variety of applications are discussed using model prokaryotic and eukaryotic organisms from the set of bacteria (Escherichia coli), trypanosomes (Trypanosoma brucei), yeast (Saccharomyces cerevisiae), slime molds (Physarum polycephalum), worms (Caenorhabditis elegans), flies (Drosophila melangoster), plants (Arabidopsis thaliana), and mouse immune cells (Mus musculus). Other engineering and biochemical methods discussed include biomimetics, organ on a chip, inkjet, droplet microfluidics, biotic games, and diagnostics. While we have not yet reached the end-all lab on a chip, microfluidics can still be used effectively for specific applications

A Speculative Bubble in Commodity Futures Prices? Cross-Sectional Evidence

Recent accusations against speculators in general and long-only commodity index funds in particular, include: increasing market volatility, distorting historical price relationships, and fueling a rapid increase and decrease in commodity inflation. Some researchers have argued that these market participants—through their impact on market prices—may inadvertently prevented the efficient distribution of food aid to deserving groups. Certainly, this result—if substantiated— would counter the classical argument that speculators make prices more efficient and thus improve the economic efficiency of the agricultural and food marketing system. Given the very important policy implications, it is crucial to develop a more thorough understanding of long-only index funds and their potential market impact. Here, we review the criticisms (and rebuttals) levied against (and for) commodity index funds in recent U.S. Congressional testimonies. Then, additional empirical evidence is added regarding cross-sectional market returns and the relative levels of long-only index fund participation in 12 commodity futures markets. The results suggest that index fund positions across futures markets have no impact on relative price changes across those markets. The empirical results provide no evidence that long-only index funds impact commodity futures prices.Commitment’s of Traders, index funds, commodity futures markets, Agribusiness, Agricultural Finance, Farm Management, Financial Economics, Research Methods/ Statistical Methods, Risk and Uncertainty,

Temporal variability in nutrient transport in a first-order agricultural basin in southern Ontario

This thesis examines phosphorus and nitrate transport in a first-order agricultural catchment in Southern Ontario. Specific areas of concern relate to (1) long- and short-term temporal variability in nutrient export patterns, (2) the role of drainage tiles in annual nutrient export, (3) the effects of antecedent hydrologic conditions (AHC) on nutrient export patterns and (4) temporal variability in the nutrient retention in riparian buffer strips and streams. Temporal variability in hydrochemical export from the study basin over a two-year period is described and quantified and the importance of high magnitude events is highlighted. This is the first comprehensive study to examine the role of such events in annual nutrient export from agricultural catchments (17-58% of annual nutrient export). The significance of winter thaws and in particular major snowmelt events in annual nutrient export from agricultural catchments in Southern Ontario is shown and the need to include the winter period in sampling regimes is demonstrated. The importance of sampling frequency is examined and an improved sampling strategy is suggested for the study basin. The role of drainage tiles in annual hydrochemical export from the basin is quantified and the dominance of drainage tiles as a nutrient source is shown. Tiles account for approximately 42% of annual discharge, but account for the majority of SRP, TP and NO3-export. Tiles within the study basin exhibit spatial and temporal variability in hydrochemical export patterns but the discharge from all tiles within the basin can be predicted from one continuously monitored tile. The effect of antecedent hydrologic conditions in hydrochemical export and the complex effects of successive events on hydrochemical export patterns are also demonstrated. In general, hydrochemical export increases as conditions become successively wetter, although empirical relationships between hydrological variables in the catchment and hydrochemical export are weak. Hydrologic connectivity between surface horizons and drainage tiles by macropores and preferential flowpaths appears to be critical in exporting nutrients from the catchment, and the role of these flowpaths increases as conditions become wetter. The in-stream retention of phosphate during low flows is examined. Stream sediments are unable to retain large pulses of phosphate during very low flow periods due to poor mixing in the water column. The stream is therefore unable to retain pulses of phosphate that may occur following the irrigation of fields receiving liquid manure applications or when fertilizers are directly applied into ditches. These individual studies improve our general understanding of nutrient dynamics and export from agricultural watersheds. This thesis increases our ability to predict nutrient export by (a) suggesting a new sampling strategy to improve the precision of nutrient export estimates in basins; and (b) identifying critical periods of nutrient export and linking these to antecedent hydrologic conditions in the basin