Conceptual design of adaptive structural control systems

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.Includes bibliographical references (leaves 147-148).by Michael Cusack.S.M

Phospholipid composition and kinetics in different endobronchial fractions from healthy volunteers

Tracheal secretions may be of value as a surrogate to assess bronchoalveolar lavage fluid surfactant molecular composition and metabolism in healthy people. Despite minor differences, the phospholipid molecular composition of induced sputum also showed similarities to that of bronchoalveolar lavage fluid. Detailed analysis of newly synthesized individual phosphatidylcholine species provided novel insights into mechanisms of surfactant synthesis and acyl remodelling. Lysophosphatidylcholine methyl-D9 incorporation patterns suggest that these species are secreted together with other surfactant phospholipids and are not generated in the air spaces by hydrolysis of secreted surfactant phosphatidylcholine. Application into patient populations may elucidate potential underlying pathophysiological mechanisms that lead to surfactant alterations in disease state

Source apportionment of fine PM and sub-micron particle number concentrations at a regional background site in the western Mediterranean: a 2.5 year study

The chemical composition and sources of ambient fine particulate matter (PM₁) over a period of 2.5 years for a regional background site in the western Mediterranean are presented in this work. Furthermore, sub-micron particle number concentrations and the sources of these particles are also presented. The mean PM₁ concentration for the measurement period was 8.9 μgm¯³, with organic matter (OM) and sulphate comprising most of the mass (3.2 and 1.5 μgm¯³ respectively). Six sources were identified in PM₁ by Positive Matrix Factorisation (PMF): secondary organic aerosol, secondary nitrate, industrial, traffic + biomass burning, fuel oil combustion and secondary sulphate. Typically anthropogenic sources displayed elevated concentrations during the week with reductions at weekends. Nitrate levels were elevated in winter and negligible in summer, whereas secondary sulphate levels underwent a contrasting seasonal evolution with highest concentrations in summer, similar to the fuel oil combustion source. The SOA source was influenced by episodes of sustained pollution as a result of anticyclonic conditions occurring during winter, giving rise to thermal inversions and the accumulation of pollutants in the mixing layer. Increased levels in summer were owing to higher biogenic emissions and regional recirculation of air masses. The industrial source decreased in August due to decreased emissions during the vacation period. Increases in the traffic + biomass burning source were recorded in January, April and October, which were attributed to the occurrence of the aforementioned pollution episodes and local biomass burning emission sources, which include agriculture and domestic heating systems. Average particle number concentrations (N₉_₈₂₅ nm) from 5/11/2010 to 01/06/2011 and from 15/10/2011 to 18/12/2011 reached 3097 cm¯³. Five emission sources of particle of sub-micron particles were determined by Principal Component Analysis (PCA); industrial + traffic + biomass burning, new particle formation + growth, secondary sulphate + fuel oil combustion, crustal material and secondary nitrate. The new particle formation + growth source dominated the particle number concentration (56% of total particle number concentration), especially for particles 100 nm) and thus did not influence the particle number concentration significantly

Trends of particulate matter (PM₂.₅) and chemical composition at a regional background site in the Western Mediterranean over the last nine years (2002-2010)

The time variability and long term trends of PM₂.₅ (particulate matter of diameter <2.5 μm) at various regional background (RB) sites across Europe are studied and interpreted in this work. Data on mean annual levels of PM₂.₅ measured at Montseny (MSY, North East Spain) and various RB sites in Spain and Europe are evaluated and compared, and subsequently analysed for statistically significant trends. The MSY site registered higher average PM₂.₅ levels than those measured at a selection of other RB sites across Spain, Portugal, Germany and Scandinavia by percentage compared to the mean of all the stations in these countries, but lower than those measured in Switzerland, Italy and Austria. Reductions in PM₂.₅ were observed across all stations in Spain and Europe to varying degrees (7-49%). MSY underwent a statistically significant reduction since measurements began, indicating a year-on-year gradual decrease (−3.7 μgm¯³, calculated from the final year of data compared to the mean). Similar trends were observed in other RB sites across Spain (−1.9 μgm¯³). Reductions recorded in PM₂.₅ across Europe were varied, with many experiencing gradual, year-on-year decreases (−1.8 μgm¯³). These reductions have been attributed to various causes: the introduction and implementation of pollution abatement strategies in EU member states, the effect of the current economic crisis on emissions of PM₂.₅ and the influence of meteorology observed during the winters of 2009 and 2010. In addition, the North Atlantic Oscillation (NAO), a large scale meteorological phenomenon most prevalent during winter, was observed to influence the frequency of Saharan dust intrusions across the Iberian Peninsula. Chemical composition of PM₂.₅ at MSY is characterised by high levels of organic matter (OM) and sulphate, followed by crustal material, nitrate and ammonia. Sea Spray and elemental carbon (EC) comprised a minor part of the total PM₂.₅ mass. Statistical trend analysis was performed on the various chemical components of PM₂.₅ recorded at MSY to determine which components were accountable for the decrease in PM₂.₅ concentration. It is shown that OM underwent the largest decrease over the time period with a statistically significant trend (−1.3 μgm¯³ compared to the mean), followed by sulphate (−0.8 μgm¯³), ammonium (−0.5 μgm¯³) and nitrate (−0.4 μgm¯³). Conversely, sea spray, EC and crustal a material reductions were found to be negligible

Perceptions of diagnosis and management of patients with acute respiratory distress syndrome: a survey of United Kingdom intensive care physicians

BackgroundAcute respiratory distress syndrome (ARDS) is a potentially devastating refractory hypoxemic illness with multi-organ involvement. Although several randomised controlled trials into ventilator and fluid management strategies have provided level 1 evidence to guide supportive therapy, there are few, established guidelines on how to manage patients with ARDS. In addition, and despite their continued use, pharmacotherapies for ARDS disease modulation have no proven benefit in improving mortality. Little is known however about the variability in diagnostic and treatment practices across the United Kingdom (UK). The aim of this survey, therefore, was to assess the use of diagnostic criteria and treatment strategies for ARDS in critical care units across the UK.MethodsThe survey questionnaire was developed and internally piloted at University Hospital Southampton NHS Foundation Trust. Following ethical approval from University of Southampton Ethics and Research Committee, a link to an online survey engine (Survey Monkey) was then placed on the Intensive Care Society (UK) website. Fellows of The Intensive Care Society were subsequently personally approached via e-mail to encourage participation. The survey was conducted over a period of 3 months.ResultsThe survey received 191 responses from 125 critical care units, accounting for 11% of all registered intensive care physicians at The Intensive Care Society. The majority of the responses were from physicians managing general intensive care units (82%) and 34% of respondents preferred the American European Consensus Criteria for ARDS. There was a perceived decline in both incidence and mortality in ARDS. Primary ventilation strategies were based on ARDSnet protocols, though frequent deviations from ARDSnet positive end expiratory pressure (PEEP) recommendations (51%) were described. The majority of respondents set permissive blood gas targets (hypoxia (92%), hypercapnia (58%) and pH (90%)). The routine use of pharmacological agents is rare. Neuromuscular blockers and corticosteroids are considered occasionally and on a case-by-case basis. Routine (58%) or late (64%) tracheostomy was preferred to early tracheostomy insertion. Few centres offered routine follow-up or dedicated rehabilitation programmes following hospital discharge.ConclusionsThere is substantial variation in the diagnostic and management strategies employed for patients with ARDS across the UK. National and/or international guidelines may help to improve standardisation in the management of ARDS

Airborne Prokaryote and Virus Abundance Over the Red Sea

Aeolian dust exerts a considerable influence on atmospheric and oceanic conditions negatively impacting human health, particularly in arid and semi-arid regions like Saudi Arabia. Aeolian dust is often characterized by its mineral and chemical composition; however, there is a microbiological component of natural aerosols that has received comparatively little attention. Moreover, the amount of materials suspended in the atmosphere is highly variable from day to day. Thus, understanding the variability of atmospheric dust loads and suspended microbes throughout the year is essential to clarify the possible effects of dust on the Red Sea ecosystem. Here, we present the first estimates of dust and microbial loads at a coastal site on the Red Sea over a 2-year period, supplemented with measurements from dust samples collected along the Red Sea basin in offshore waters. Weekly average dust loads from a coastal site on the Red Sea ranged from 4.6 to 646.11 μg m−3, while the abundance of airborne prokaryotic cells and viral-like particles (VLPs) ranged from 77,967 to 1,203,792 cells m−3 and from 69,615 to 3,104,758 particles m−3, respectively. To the best of our knowledge, these are the first estimates of airborne microbial abundance in this region. The elevated concentrations of resuspended dust particles and suspended microbes found in the air indicate that airborne microbes may potentially have a large impact on human health and on the Red Sea ecosystem.En prens

Neural activation differences in amputees during imitation of intact versus amputee movements

The mirror neuron system (MNS) has been attributed with increased activation in motor-related cortical areas upon viewing of another's actions. Recent work suggests that limb movements that are similar and dissimilar in appearance to that of the viewer equivalently activate the MNS. It is unclear if this result can be observed in the action encoding areas in amputees who use prosthetic devices. Intact subjects and upper extremity amputee prosthesis users were recruited to view video demonstrations of tools being used by an intact actor and a prosthetic device user. All subjects pantomimed the movements seen in the video while recording electroencephalography (EEG). Intact subjects showed equivalent left parietofrontal activity during imitation planning after watching the intact or prosthetic arm. Likewise, when prosthesis users imitated prosthesis demonstrations, typical left parietofrontal activation was observed. When prosthesis users imitated intact actors, an additional pattern was revealed which showed greater activity in right parietal and occipital regions that are associated with the mentalizing system. This change may be required for prosthesis users to plan imitation movements in which the limb states between the observed and the observer do not match. The finding that prosthesis users imitating other prosthesis users showed typical left parietofrontal activation suggests that these subjects engage normal planning related activity when they are able to imitate a limb matching their own. This result has significant implications on rehabilitation, as standard therapy involves training with an intact occupational therapist, which could necessitate atypical planning mechanisms in amputees when learning to use their prosthesis

Application of ultraviolet-C radiation and gaseous ozone for microbial inactivation on different materials

[Image: see text] With the advent of the COVID-19 pandemic, there has been a global incentive for applying environmentally sustainable and rapid sterilization methods, such as ultraviolet-C radiation (UVC) and ozonation. Material sterilization is a requirement for a variety of industries, including food, water treatment, clothing, healthcare, medical equipment, and pharmaceuticals. It becomes inevitable when devices and items like protective equipment are to be reused on/by different persons. This study presents novel findings on the performance of these sterilization methods using four microorganisms (Escherichia coli,Staphylococcus aureus,Candida albicans, and Aspergillus fumigatus) and six material substrates (stainless steel, polymethyl methacrylate, copper, surgical facemask, denim, and a cotton-polyester fabric). The combination of both ozone and UVC generally yields improved performance compared to their respective applications for the range of materials and microorganisms considered. Furthermore, the effectiveness of both UVC and ozone was higher when the fungi utilized were smeared onto the nonabsorbent materials than when 10 μL droplets were placed on the material surfaces. This dependence on the contaminating liquid surface area was not exhibited by the bacteria. This study highlights the necessity of adequate UVC and ozone dosage control as well as their synergistic and multifunctional attributes when sterilizing different materials contaminated with a wide range of microorganisms