The Effects of Thermoperiod on the Carbon Dioxide Uptake and Compensation Point of the Pineapple Plant, Ananas comosus (L.) Merr.

The effects of several thermoperiods on the co2 compensation points and CO2 uptake rates of the youngest fully expanded leaf of pineapple (Ananas comosus (L.) Merr.) were measured. Three to nine days of adaptation at a specific thermoperiod were required to obtain uniform uptake rates. CO2 compensation points, determined just after the lights were turned on, varied from a high of 170 ppm at a 35 C light-15 C dark thermoperiod to O ppm at a constant temperature of 25 C. Values for the other thermoperiods generally decreased as the difference between the light and dark temperature was decreased. The results indicate involvement of different enzyme systems in CO2 fixation at the different thermoperiods. The CO2 equilibrium, with no CO2 supplied, was monitored continuously for periods up to 4 days. At 20 C in the dark essentially all the CO2 was extracted from the sealed chamber. Extraction efficiency of the leaf in the dark decreased with increasing temperature. In the light at a 35 C light-30 C dark thermoperiod, the CO2 concentration ranged from 69 to 200 ppm. Lower maxima were measured at a dark temperature of 20 C and at a 25 C light-20 C dark thermoperiod. No diurnal cycling in the CO2 concentration was observed in continuous light or dark at constant temperatures of 20 or 25 C. When the co2 concentration was maintained at 300 ppm, co2 uptake was maximal at the constant thermoperiods and ranged from 53 to 109 mg dm-2 for 24 hours as temperature was increased from 15 to 30 C. Fixation decreased to 50 percent of the maximum at a constant temperature of 35 C. At a constant dark temperature, the mg of co2 fixed in the light and total mg for 24 hours decreased as the temperature of the light period was increased from 15 to 40 C. When the difference between the light and dark temperatures was 5 C or greater, 15 to 20 mg co2 dm-2 were fixed in the dark even at temperatures of 30 C. The percent of CO2 fixed in the dark ranged from Oat a constant temperature of 25 C to 86 at a 40 C light-25 C dark thermoperiod. Total co2 fixation decreased as the percent of CO2 fixed in the dark increased. The dominant factor determining CO2 fixation rates of pineapple under these conditions appeared to be the amount of CO2 fixed in the dark. Dark fixation was determined primarily by the difference between the light and dark temperature and, to a lesser degree, by the actual temperature

When do we eat? An evaluation of food items input into an electronic monitoring application

We present a formative study that examines what, when, and how participants in a chronic kidney disease (stage 5) population input food items into an electronic intake monitoring application. Participants scanned food item barcodes or voice recorded food items they consumed during a three week period. The results indicated that a learning curve was associated with barcode scanning; participants with low literacy skills had difficulty describing food items in voice recordings; and participants input food items depending on when they had dialysis treatment. Participants thought this electronic self monitoring application would be helpful for chronically ill populations in their first year of treatmen

Methodological approaches in the investigation of sex & gender in cardiovascular disease

Background: Differences exist in the presentation, pathophysiology, management, and outcomes of cardiovascular conditions in men and women. These differences may arise from sex-dependent factors such as chromosomal complement, regulation of sex hormones, and sex-specific factors like pregnancy. Beyond sex, gender, a multifaceted psychosocial concept, also has an impact on cardiovascular health and disease. Transgender individuals experience incongruence between the sex they were assigned at birth and their gender identity. These individuals may engage with gender-affirming hormone therapy (GAHT), such as oestrogen or testosterone, and the effects of such treatments upon cardiovascular health have yet to be determined, and may provide insight into cardiovascular pathophysiology. Aims: This thesis aims to enhance our understanding of the role of sex and gender in cardiovascular disease, including transgender cardiovascular health, through a range of methodological approaches. Methods: Chapter 3) A systematic review assessing the influence of GAHT upon the blood pressure of transgender individuals is undertaken; Chapter 4) The Gender and Sex Determinants of Cardiovascular Disease: From Bench to BeyondPremature Acute Coronary Syndrome (GENESIS-PRAXY) gender stratification questionnaire is adapted and applied to a UK sample of cisgender individuals (n=446) to construct a gender score via principal component analysis (PCA); Chapter 5) A bioinformatic analysis of sex and gender stratified differentially expressed microRNA (miRNAs) in human plasma of individuals (n=36), derived from the original GENESIS-PRAXY study, who have experienced acute coronary syndrome (ACS) is undertaken; Chapter 6) A descriptive analysis of the Vascular Effects of Sex Steroids in Transgender Adults (VESSEL) study, which utilises a range of vascular phenotyping procedures (e.g. flow-mediated dilatation, peripheral artery tonometry, and pulse wave analysis (PWA) and velocity (PWV)) in transgender individuals using long-term GAHT compared to cisgender individuals is presented. Results: Chapter 3) The systematic review identified 14 studies including 1,309 transgender individuals, which demonstrated broadly no change in blood pressure in transmasculine individuals using testosterone. Both increases and decreases were observed within the transfeminine population using oestrogen therapy. These studies were of limited quality due to their uncontrolled pre-post design, lack of intervention and blood pressure measurement standardisation, inadequate follow up and small sample sizes; Chapter 4) The gender stratification analysis demonstrated a continuum of gender scores in this population derived from five gender-related questionnaire instruments. Gender score distributions were distinct from the GENESIS-PRAXY analysis, highlighting that gender and its related factors are dynamic and context dependent; Chapter 5) miR-664a-5p, miR-36135p, miR-382-5p, miR-134-5p, miR-10b-5p, miR-885-5p, miR-206, and miR-32-5p were found to be differentially expressed in females versus males in ACS. Many of these miRNA and associated gene networks demonstrate a number of roles important to ACS pathophysiology including the regulation of vascular smooth muscle cell proliferation, endothelial injury and inflammation, atherosclerosis progression. miR-3605-5p and miR-4467 were differentially expressed in males with feminine versus masculine gender characteristics; Chapter 6) Due to the impact of coronavirus disease 2019 (COVID-19), the VESSEL study was discontinued prematurely, however, the feasibility of local recruitment of transgender participants is demonstrated. Discussion: This thesis expands our appreciation of the means by which gender can be measured and its potential influence, in addition to sex, upon epigenomic regulation in cardiovascular disease. Moreover, it improves our understanding of limitations and barriers in conducting research in transgender populations. Overall, this thesis provides valuable insight into the methodological approaches used the investigation of sex and gender in cardiovascular disease, which can be applied in future cardiovascular research in cisgender and transgender populations

GSA Launches G3: Genes | Genomes | Genetics

We are proud to present the inaugural issue of G3: Genes | Genomes | Genetics, an open-access journal published by the Genetics Society of America (GSA). The journal’s team of over 60 associate editors and 4 section editors, all practicing scientists—your peers—have come together to form a new, open-access journal with a unique mission and vision. The Editorial Board of G3 taps the expertise of the community of geneticists in the widest sense, from microbes to humans, from individuals to populations, and from classic “wet lab” experimentation to the most recent innovations in bioinformatics

Passive acoustic tracking of divers and dolphins

This thesis describes work performed in the analysis and development of positioning algorithms for self-noise of a known kind; it also describes the development of short base-line systems capable of positioning the sources. Many studies of wild cetaceans rely on tracking the movement of wild animals, often in hostile conditions and with limited contact with these animals. Advanced technology exists for satellite or radio tracking of marine wildlife, but this relies on an animal being first caught and tagged. In situations where random interactions with marine wildlife are to be analysed, it is not practicable to attach devices to an animal, so it is appropriate to use passive techniques, in which the animal's self noise is located and tracked. Present passive systems usually include a long base-line array, which can be difficult to deploy. The problem may be overcome by reducing the array in size, but it results in an increase in positioning errors. This study attempts to quantifY these errors and looks into the practicability of short base-line passive arrays. Two systems are described here, both for tracking impulsive sounds in real time. The first is for use on pelagic trawl nets, the other as a prototype high-speed system to prove the different algorithms developed before and during this study. The prototype systems, each having a minimum of four receivers positioned in various configurations, have been tested in a tank with a controlled sound source. The source is a 'pinger', which allows the systems also to be adopted for diver positioning and tracking. A survey of unclassified literature has shown characteristics of cetacean acoustic signatures, which have been utilised in the optimisation of the systems. The physiology of cetaceans has also been reviewed to help understand the physical limitations of the systems presented.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Development of a simplified ray path model for estimating the range and depth of vocalising marine mammals

A simplified ray path model has been developed to simulate various source, receiver geometries. The difference in the arrival time of the multi-path signals (surface and seabed reflections) were calculated and compared with those measured on recorded data obtained during sea trials. A number of assumption have been made in initial models including a constant sound velocity-depth profile and the treatment of the surface and seabed as a simple reflecting surfaces. Initial results have shown a number of examples with a reasonable correlation between estimated position of a submerged cetacean and the associated surface observations. Examples of multiple (positioning) solutions were however found, these are in the main thought to be due to imprecision in the knowledge of the hydrophone and water depth and inaccuracies in the initial timing measurements. The use of correlation techniques and stand-alone depth measurement devices is therefore proposed for future measurements and analysis using this technique. It is felt that within constraints, this technique provides valuable additional information regarding cetacean behaviour in the wild and can be used on recorded data sets to validate observer records. The addition of more complex time measurement techniques and better ray path modelling will hopefully provide a useful analysis tool in the study of cetaceans