Natural ventilation in multi-storey buildings: a preliminary design approach

Natural ventilation is a low-energy design strategy that has the potential both to significantly reduce energy usage in buildings and to provide a healthy and comfortable indoor environment. It has particular potential for use in tall, multi-storey buildings. However, the integration of natural ventilation into these large building designs has seen mixed success. Furthermore, there is a gap between simple 'rule-of-thumb' design guidance and detailed, computational design tools. This research attempts to bridge the gap between the simple and detailed with the broad aim of providing rapid and intuitive guidance for use in preliminary design. We use a simple mathematical approach to develop a coherent and easy-to-use framework for modelling ventilating flows, which quantifies the interactions between a core set of design variables. We focus in particular on buoyancy-driven ventilation in buildings with atria, ventilation stacks and/or similar vertical spaces that span multiple floors. Simple methods centred around hand calculations and design charts are developed to inform the sizing of vents in an 'ideal design' scenario, in which the desired ventilation flow rates and air temperatures are delivered to all occupants within a building. We define a measure of the ventilation performance of an atrium and use this to provide an indication of when an atrium is beneficial to a ventilation system design and when it is detrimental. We also use a transient flow analysis to consider 'off-design' scenarios, in which undesirable flow regimes may occur, and to place design tolerances on the building envelope. It is hoped that this work will form a point of reference for further research and for future revisions of design guidance literature.Open Acces

Opioid Free Anesthesia to Prevent Post Operative Nausea/Vomiting

Purpose The purpose of this study is to compare the incidence of post-operative nausea and vomiting (PONV) in opioid-utilizing and opioid-free general anesthesia. Background PONV is an extremely common, potentially dangerous side effect of general anesthesia. PONV is caused by a collection of anesthetic and surgical interventions. Current practice to prevent PONV is to use 1-2 antiemetics during surgery, identify high risk patients and utilize tracheal intubation over laryngeal airways when indicated. Current research suggests minimizing the use of volatile anesthetics and opioids can reduce the incidence of PONV, but this does not reflect current practice. Methods In this scoping review, the MeSH search terms used to collect data were “anesthesia”, “postoperative nausea and vomiting”, “morbidity”, “retrospective studies”, “anesthesia, general”, “analgesics, opioid”, “pain postoperative”, “pain management” and “anesthesia, intravenous”. The Discovery Search engine, AccessMedicine and UpToDate were the search engines used to research this data. Filters were applied to these searches to ensure all the literature was peer-reviewed, full-text and preferably from academic journals. Results Opioid free anesthesia was found to decrease PONV by 69%. PONV incidence was overwhelming decreased with opioid free anesthesia in every study that was reviewed. Implications The future direction of opioid-free anesthesia and PONV prevention are broad topics to discuss, due to the nature of anesthesia. Administration of TIVA, esmolol and ketamine, as well as the decision to withhold opioids, are solely up to the anesthesia provider’s discretion. Increasing research and education in the importance of opioid-free anesthesia to decrease the incidence of PONV will be necessary to ensure anesthesia providers choose this protocol in their practice

Oral Passive Immunization With Plasma-Derived Polyreactive Secretory-Like IgA/M Partially Protects Mice Against Experimental Salmonellosis.

Secretory immunoglobulins have a critical role in defense of the gastrointestinal tract and are known to act by preventing bacterial acquisition. A stringent murine model of bacterial infection with Salmonella enterica Typhimurium was used to examine protection mediated by oral passive immunization with human plasma-derived polyreactive IgA and IgM antibodies (Abs) reconstituted as secretory-like immunoglobulins (SCIgA/M). This reagent has been shown to trigger Salmonella agglutination and to limit the entry of bacterium into intestinal Peyer's patches via immune exclusion. We now demonstrate that upon administration into ligated intestinal loops, SCIgA/M properly anchors in the mucus and is protected from degradation to a better extent that IgA/M or IgG. Moreover, prophylactic oral administration of SCIgA/M before intragastric infection of mice with a virulent strain of S. enterica Typhimurium allows to protect infected animals, as reflected by reduced colonization of both mucosal and systemic compartments, and conserved integrity of intestinal tissues. In comparison with IgA/M or IgG administration, SCIgA/M provided the highest degree of protection. Moreover, such protective efficacy is also observed after therapeutic oral delivery of SCIgA/M. Either prophylactic or therapeutic treatment with passively delivered SCIgA/M ensured survival of up to 50% of infected mice, while untreated animals all died. Our findings unravel the potential of oral passive immunization with plasma-derived polyreactive SCIgA/M Abs to fight gastrointestinal infections

Beta-lactam antibiotics: from antibiosis to resistance and bacteriology

This review focuses on the era of antibiosis that led to a better understanding of bacterial morphology, in particlar the cell wall component peptidoglycan. This is an effort to take readers on a tour de force from the concept of antibiosis, to the serepidity of antibiotics, evolution of betalactam development, and the molecular biology of antibiotic resistance. These areas of research have culminated in a deeper understanding of microbiology, particularly in the area of bacterial cell wall synthesis and recycling. In spite of this knowledge, which has enabled design of new even more effective therapeutics to combat bacterial infection and has provided new research tools, antibiotic resistance remains a worldwide health care problem

Urban Heat Island Effects Seen through Acer rubrum Phenology

The Urban Heat Island (UHI) effect can raise average temperatures around urban areas, especially those with a lot of impervious surfaces that act as heat sinks. The hypothesis explored here is that UHIs will have an effect on dates of leaf bud-break in red maples (Acer rubrum). The USA National Phenology Network (USANPN) brings together citizen scientists, researchers, educators, students, and anyone else with an interest in living organisms. These people record phenological data across the United States and add it to the USANPN’s database. We plotted entries for red maple from the database using GPS coordinates and grouped them into urban and rural categories at matching latitudes. We then compared the average date of leaf bud-break for each group of urban trees to the average leaf bud-break date for rural trees at the same latitude. The data for more than half of our samples went back 7 seasons, allowing our samples to not be skewed by an abnormally warm or cool spring. If the hypothesis is valid, the data will show significantly earlier leaf bud-break dates for the urban red maples than for the rural red maples. This would demonstrate that urban environment can influence the phenology of red maples. Some UHIs could be strong enough to change hardiness zones and allow for certain species of trees to be grown at colder latitudes than nature would allow without human intervention

A simplified mathematical approach for modelling stack ventilation in multi-compartment buildings

A simple mathematical model of stack ventilation flows in multi-compartment buildings is developed with a view to providing an intuitive understanding of the physical processes governing the movement of air and heat through naturally ventilated buildings. Rules of thumb for preliminary design can be ascertained from a qualitative examination of the governing equations of flow, which elucidate the relationships between 'core' variables - flow rates, air temperatures, heat inputs and building geometry. The model is applied to an example three-storey office building with an inlet plenum and atrium. An examination of the governing equations of flow is used to predict the behaviour of steady flows and to provide a number of preliminary design suggestions. It is shown that control of ventilation flows must be shared between all ventilation openings within the building in order to minimise the disparity in flow rates between storeys, and ensure adequate fresh air supply rates for all occupants. © 2013 Elsevier Ltd