The effect of suspending agents on the suspension polymerization of vinyl chloride

The suspension polymerisation of vinyl chloride is the main industrial process used for the manufacture of PVC. The aim of this project was to study the suspension polymerisation of vinyl chloride monomer to form PVC. The work concentrated on the effects that the choice of suspension stabilisers (PVA's), pH and other environmental factors had on the properties of both the initial droplet suspension and the polymerising system throughout the course of the reaction. Experiments were carried out using a pressurised 11 stainless steel jacketed reactor connected to an external optical cell. Progress of the polymerisation was monitored optically by taking samples into the cell at regular intervals and examining them with a microscope which had an attached camera. Properties that were studied included the drop size and drop size distribution of the initial droplet suspension, the stabiliser take-up during the reaction and the particle size distribution, porosity and physical appearance of the polymer particles. The work showed that the choice of suspension stabiliser not only effected the drop size and drop size distribution of the initial suspension but also effected the properties and particle size of the final polymer product which was produced. The pH of the system was also discovered to effect both drop stability and the course of the polymerisation. Lowering the pH (pH 10) had a drastic effect. At high pH, the droplet suspension that was formed was highly unstable and the polymer product that was formed consisted of very large, coarse grains. Other environmental factors (reactor heat up rate, oxygen concentration, the location of secondary PVA (aqueous or organic phase), delaying the addition of the primary PVA and simultaneous charging of both phases to the reactor) were also discovered to effect the properties of both the droplet suspension and the polymer product although the suspension was found to be more resilient to changes in the operating conditions than the polymer

Places & Spaces: A Critical Analysis of Cancer Disparities and Access to Cancer Care Among First Nations Peoples in Canada

Despite advancements in research and medicine, health inequities and disparities among First Nations peoples (FN) in Canada are well documented and continue to grow. Once virtually unheard of, cancer now is a leading cause of death among FN. Many factors contribute to cancer disparities, but FN face unique challenges in accessing healthcare. In this critical review and analysis, we explore potential links between cancer disparities and poor access to cancer care among FN. Research suggests FN experience difficulty accessing cancer services in several ‘places’ of care, including screening, diagnosis, treatment, survivorship and palliative care. Furthermore, there are notable ‘spaces’ or gaps both within and between these ‘places’ of care likely contributing to cancer disparities among First Nations. Gaps in care result from jurisdictional ambiguities, geographical location, unsafe social spaces, and marginalization of FN ways of knowing, and can be linked to colonial and neocolonial policies and ideologies. By drawing attention to these broader structural influences on health, we aim to challenge discourses that attribute growing cancer disparities among FN in Canada solely to increases in ‘risk factors’

Demographic genetics of the polymorphism for capitulum type and associated outcrossing rate in 'Senecio vulgaris L.'

The primary aim of this project was to examine factors which are likely to provide a mechanism by which the polymorphism for capitulum type and associated outcrossing rate in Senecio vulgaris may be maintained. The majority of studies conducted examined the demographic genetics (i.e. the changes in the number of individuals of the two morphs at different life history stages) in field experiments initiated either in Spring or Autumn, The first series examined the demography of each morph raised from seedlings to senescence in pure stand and mixture. The second series examined the demography of each morph from seed to senescence and thereby investigated the effect on fitness of any difference between morphs in germination behaviour. The importance of inbreeding depression on the maintenance of the polymorphism was examined by comparing the relative fitness of self and open pollinated offspring of each morph under glasshouse conditions. Germination behaviour of seeds of each morph was also investigated in a series of field trials conducted over an extended period. These field studies were complemented by a series of synchronous laboratory studies to examine the effect of temperature on morph germination behaviour. It was found that inbreeding depression is not an important factor in the maintenance of the polymorphism. No short term advantage of the radiate over the non-radiate morph was evident in the first series of demography experiments. The germination studies showed that differences between morphs in germination behaviour may occur frequently in autumn sown seed. The second series of demography experiments showed that under certain conditions this difference in germination can lead to the radiate morph attaining a greater relative fitness than the non-radiate morph. Temperature was found to be a major factor controlling the initial dormancy of seeds after sowing. It is concluded that the difference between morphs in germination behaviour is the most likely factor that could maintain the polymorphism for capitulum type in Edinburgh populations of 8. vulgaris

Tackling invasive alien species in Europe: The top 20 issues

Globally, Invasive Alien Species (IAS) are considered to be one of the major threats to native biodiversity, with the World Conservation Union (IUCN) citing their impacts as ‘immense, insidious, and usually irreversible’. It is estimated that 11% of the c. 12,000 alien species in Europe are invasive, causing environmental, economic and social damage; and it is reasonable to expect that the rate of biological invasions into Europe will increase in the coming years. In order to assess the current position regarding IAS in Europe and to determine the issues that were deemed to be most important or critical regarding these damaging species, the international Freshwater Invasives - Networking for Strategy (FINS) conference was convened in Ireland in April 2013. Delegates from throughout Europe and invited speakers from around the world were brought together for the conference. These comprised academics, applied scientists, policy makers, politicians, practitioners and representative stakeholder groups. A horizon scanning and issue prioritization approach was used by in excess of 100 expert delegates in a workshop setting to elucidate the Top 20 IAS issues in Europe. These issues do not focus solely on freshwater habitats and taxa but relate also to marine and terrestrial situations. The Top 20 issues that resulted represent a tool for IAS management and should also be used to support policy makers as they prepare European IAS legislation. © 2014 The Author(s)

Performance of a prehospital HEART score in patients with possible myocardial infarction: a prospective evaluation

Introduction The History, Electrocardiogram (ECG), Age, Risk Factors and Troponin (HEART) score is commonly used to risk stratify patients with possible myocardial infarction as low risk or high risk in the Emergency Department (ED). Whether the HEART score can be used by paramedics to guide care were high-sensitivity cardiac troponin testing available in a prehospital setting is uncertain. Methods In a prespecified secondary analysis of a prospective cohort study where paramedics enrolled patients with suspected myocardial infarction, a paramedic Heart, ECG, Age, Risk Factors (HEAR) score was recorded contemporaneously, and a prehospital blood sample was obtained for subsequent cardiac troponin testing. HEART and modified HEART scores were derived using laboratory contemporary and high-sensitivity cardiac troponin I assays. HEART and modified HEART scores of ≤3 and ≥7 were applied to define low-risk and high-risk patients, and performance was evaluated for an outcome of major adverse cardiac events (MACEs) at 30 days. Results Between November 2014 and April 2018, 1054 patients were recruited, of whom 960 (mean 64 (SD 15) years, 42% women) were eligible for analysis and 255 (26%) experienced a MACE at 30 days. A HEART score of ≤3 identified 279 (29%) as low risk with a negative predictive value of 93.5% (95% CI 90.0% to 95.9%) for the contemporary assay and 91.4% (95% CI 87.5% to 94.2%) for the high-sensitivity assay. A modified HEART score of ≤3 using the limit of detection of the high-sensitivity assay identified 194 (20%) patients as low risk with a negative predictive value of 95.9% (95% CI 92.1% to 97.9%). A HEART score of ≥7 using either assay gave a lower positive predictive value than using the upper reference limit of either cardiac troponin assay alone. Conclusions A HEART score derived by paramedics in the prehospital setting, even when modified to harness the precision of a high-sensitivity assay, does not allow safe rule-out of myocardial infarction or enhanced rule-in compared with cardiac troponin testing alone. https://emj.bmj.com/content/40/7/474 This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0

The experiences of caregivers of Indigenous cancer survivors in Australia, Canada, New Zealand and the United States: a systematic review.

Background: Caregivers of Indigenous cancer survivors provide critical unpaid support to survivors, yet they rarely receive information or training for this role and may themselves benefit from support services. Little is documented about the experiences of caregivers of Indigenous cancer survivors. The aim of this systematic review was to identify and aggregate qualitative research describing the experiences of caregivers of Indigenous cancer survivors in Australia, New Zealand, Canada and the United States. Methods: We systematically searched PsycINFO, PubMed, CINAHL, Embase, Scopus and Web of Science using keywords relating to Indigenous populations; caregivers; and cancer. Data were extracted from original qualitative research articles published up to March 2020. Results: From 24 full-text articles, 14 articles from 13 studies were analyzed using meta-aggregation. This highlighted key caregiver experiences relating to: the need for information about cancer and services; providing and receiving support; communication challenges and responsibilities; balancing caregiver roles and emotions; and culturally unsafe health systems and settings. Caregivers of Indigenous cancer survivors often act as mediator between Western biomedical approaches to cancer care and Indigenous peoples’ holistic and family-focused views of health and wellbeing, aiming to ensure that both health professionals and the cancer survivors understand each other's perspectives and preferences for care. Caregivers expressed preferences for family-focussed rather than patient-focussed care. Culturally unsafe health care systems created barriers to optimal care. Conclusions: The findings reveal caregivers’ unique experiences of caring for an Indigenous cancer survivor, and identifies several unmet needs which should be appropriately and systematically addressed. Caregivers should be regarded as co-clients with their own needs as well as co-workers with health professionals providing cancer care. Ultimately supporting caregivers will contribute to improving health outcomes for Indigenous cancer survivors