Design and testing of a microvalve capable of precisely controlling low fluidic flow rates

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 48).Development of the design, manufacture, and testing for a gas flow regulating microvalve is presented herein. The microvalve project served as a test bed for new micromachining techniques and for exploration of MEMS devices made from non-silicon materials. We developed and tested a novel microvalve utilizing a passive mechanical membrane that allows for accurate flow rate control over a wide range of inlet pressures, requiring power only to adjust the flow rate. Design considerations and functional analysis of a microvalve system are discussed, and manufacturing techniques analyzed. The design was verified by comparing the prototyped system to a commercially available mini ball valve. The valves were run through full actuation at varying pressures and the resulting flow was observed and characterized. At 0.69 MPa, the flexure valve prototype was shown to allow adjustments in flow between 1.0* 10-6 and 2.0* 106 m3/s over the period of about 8 seconds, allowing for a precision adjustment of flow not available in other valves. The experiment demonstrates that the new microvalve offers significant advantages in terms of a wider range of flow rate adjustment available within the operating pressure regime.by Cody R. Daniel and Toomas R. Sepp.S.B

Hábitos de sono e performance académica: estudo comparativo entre Estónia e Portugal

Actualmente, na nossa sociedade, muitas das actividades diárias têm prioridade sobre o sono. A privação do sono em estudantes tem sido documentada em variados países e o problema reside no conflito entre a necessidade física e psicológica, dos estudantes, de dormir e os seus horários. Esta privação do sono é, muitas das vezes, relacionada com a diminuição do humor e do rendimento académico. No intuito de combater estes problemas, alguns estudantes recorrem ao uso de fármacos ou substâncias com vista a melhorar a sua qualidade de vida e o seu rendimento escolar. O objectivo deste estudo é (1) avaliar a qualidade de sono dos estudantes universitários, (2) avaliar a percentagem de estudantes que consomem fármacos ou substâncias para modificar o seu sono e (3) comparar os resultados entre duas escolas de saúde, Escola Superior de Tecnologia da Saúde do Porto, Portugal (ESTSP) e a Tallinn Health Care College, Estónia (THCC)

Crenças, aceitação e atitudes dos utentes perante os medicamentos genéricos: um estudo comparativo entre Portugal e Estónia

Medicamento genérico (MG) é definido como uma fiel imitação de um medicamento original, terapeuticamente equivalente apresentando a mesma forma farmacêutica, composição qualitativa e quantitativa destinado a ser intercambiável com o produto original. Os MGs só podem ser comercializados depois de todas as patentes e certificados complementares de protecção (SPCs) que cobrem o produto original terem expirado. O papel dos MGs tem sido providenciar medicamentos essenciais que são de boa qualidade e de preço acessível em toda a União Europeia e o seu uso aumentou a acessibilidade dos pacientes e proporcionou uma poupança económica significativa para os sistemas de saúde. À medida que as despesas totais em cuidados de saúde têm vindo a aumentar e a maioria dessas despesas é composta de custos fixos (nomeadamente os serviços hospitalares), a indústria farmacêutica tem sido um objectivo de poupança em todos os países da Europa, que têm reformulado os seus sistemas nacionais de saúde de modo a responder ao rápido crescimento dos gastos em saúde. Os governos preocupados com o aumento do custo de produtos farmacêuticos dentro dos seus orçamentos nacionais de saúde, estão a esforçar-se para promover a utilização de genéricos em relação aos produtos originais de preço mais elevado. Portugal e Estónia são dois países pertencentes à União Europeia. Existem algumas diferenças no sector da saúde entre os dois países, especialmente no que concerne a medicamentos, seus preços e reembolso pelos sistemas de seguro obrigatório de saúde e serviços nacionais de saúde, no entanto apresentam em comum a preocupação com o custo dos medicamentos, incentivando o uso de MGs. Actualmente a Estónia apresenta uma quota de mercado de MGs superior a Portugal, que ocupa uma posição inferior à média Europeia. À medida que os sistemas governamentais vão incentivando o uso de MGs e o seu consumo vai aumentando é importante perceber as opiniões que os consumidores têm acerca destes medicamentos. Este estudo teve como objectivo avaliar a aceitação e as crenças dos utentes sobre MGs em relação aos medicamentos de marca (MM), comparando resultados entre Portugal e Estónia

Synergistic use of Sentinel-2 and UAV-derived data for plant fractional cover distribution mapping of coastal meadows with digital elevation models

Coastal wetlands provide a range of ecosystem services, yet they are currently under threat from global change impacts. Thus, their monitoring and assessment is vital for evaluating their status, extent and distribution. Remote sensing provides an excellent tool for evaluating coastal ecosystems, whether with small-scale studies using drones or national-/regional-/global-scale studies using satellite-derived data. This study used a fine-scale plant community classification of coastal meadows in Estonia derived from a multispectral camera on board unoccupied aerial vehicles (UAVs) to calculate the plant fractional cover (PFC) in Sentinel-2 MultiSpectral Instrument (MSI) sensor grids. A random forest (RF) algorithm was trained and tested with vegetation indices (VIs) calculated from the spectral bands extracted from the MSI sensor to predict the PFC. Additional RF models were trained and tested after adding a digital elevation model (DEM). After comparing the models, results show that using DEM with VIs can increase the prediction accuracy of PFC up to 2 times (R2 58%-70%). This suggests the use of ancillary data such as DEM to improve the prediction of empirical machine learning models, providing an appropriate approach to upscale local studies to wider areas for management and conservation purposes

COST 733 - WG4: Applications of weather type classification

The main objective of the COST Action 733 is to achieve a general numerical method for assessing, comparing and classifying typical weather situations in the European regions. To accomplish this goal, different workgroups are established, each with their specific aims: WG1: Existing methods and applications (finished); WG2: Implementation and development of weather types classification methods; WG3: Comparison of selected weather types classifications; WG4: Testing methods for various applications. The main task of Workgroup 4 (WG4) in COST 733 implies the testing of the selected weather type methods for various classifications. In more detail, WG4 focuses on the following topics:• Selection of dedicated applications (using results from WG1), • Performance of the selected applications using available weather types provided by WG2, • Intercomparison of the application results as a results of different methods • Final assessment of the results and uncertainties, • Presentation and release of results to the other WGs and external interested • Recommend specifications for a new (common) method WG2 Introduction In order to address these specific aims, various applications are selected and WG4 is divided in subgroups accordingly: 1.Air quality 2. Hydrology (& Climatological mapping) 3. Forest fires 4. Climate change and variability 5. Risks and hazards Simultaneously, the special attention is paid to the several wide topics concerning some other COST Actions such as: phenology (COST725), biometeorology (COST730), agriculture (COST 734) and mesoscale modelling and air pollution (COST728). Sub-groups are established to find advantages and disadvantages of different classification methods for different applications. Focus is given to data requirements, spatial and temporal scale, domain area, specifi

Probing scalar particle and unparticle couplings in e+ e- -> t tbar with transversely polarized beams

In searching for indications of new physics scalar particle and unparticle couplings in e^+ e^- \to t\bar t, we consider the role of transversely polarized initial beams at e^+ e^- colliders. By using a general relativistic spin density matrix formalism for describing the particles spin states, we find analytical expressions for the squared amplitude of the process with t or \bar t polarization measured, including the anomalous coupling contributions. Thanks to the transversely polarized initial beams these contributions are first order anomalous coupling corrections to the Standard Model (SM) contributions. We present and analyse the main features of the SM and anomalous coupling contributions. We show how differences between SM and anomalous coupling contributions provide means to search for anomalous coupling manifestations at future e^+ e^- linear colliders.Comment: 28 pages in LaTeX, including 7 encapsulated PostScript figures, published versio

Hydrothermal dedolomitisation of carbonate rocks of the Paleoproterozoic Zaonega Formation, NW Russia — Implications for the preservation of primary C isotope signals

This study was supported by Estonian Science Agency project PUT696 and PRG447, and Estonian Centre of Analytical Chemistry. K.P. and A.L. were supported by the Research Council of Norway through its Centres of Excellence funding scheme grant No. 223259.The Paleoproterozoic Zaonega Formation in Karelia, NW Russia, has played a key role in understanding the environmental conditions postdating the Great Oxidation and Lomagundi-Jatuli Events. Its carbonate- and organic-rich rocks (shungite) define the postulated Shunga Event representing an accumulation of very organic-rich sediments at c. 2 Ga and are central in ideas about changing ocean-atmosphere composition in the wake of those worldwide biogeochemical phenomena. Our work focussed on a key interval of carbonate rocks in the upper part of the Formation to: (i) obtain new high-resolution carbon, oxygen and strontium isotope data complemented by detailed petrography and mineralogical characterisation and (ii) expand upon previous studies by using our data to constrain geochemical modelling and show in greater detail how magmatic hydrothermal fluids induced dedolomitisation and altered geochemical signals. Our findings show that the δ13Ccarb of calcite-rich intervals are the most altered, with values between −16.9 to 0.6‰, whereas the dolomite-dominated parts retain the best-preserved (i.e. most original) values. Those define a trend of steadily increasing δ13Ccarb, from −6 to +0.5‰, which we interpret as a return to normal marine conditions and carbonate‑carbon values following the Lomagundi-Jatuli Event.PostprintPeer reviewe

Mid-to Late Holocene East Antarctic ice-core tephrochronology : implications for reconstructing volcanic eruptions and assessing their climatic impacts over the last 5,500 years

PA and MS received funding from the European Research Council under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 820047). WH is funded by a UKRI Future Leaders Fellowship (MR/S033505/1). Continuous analysis of the B53 and B54 cores for sulphur and insoluble particles was supported by internal funding from the Desert Research Institute, with partial support for interpretation provided by National Science Foundation grant 1925417 to JRM.Ice cores are powerful archives for reconstructing volcanism as they contain both soluble (i.e. aerosols) and insoluble (i.e. tephra) products of volcanic eruptions and for more recent periods have high-precision annually resolved chronologies. The identification and geochemical analysis of cryptotephra in these cores can provide their volcanic source and latitude of injection, complementing records of sulphur injections from volcanic eruptions developed using continuous flow ice-core analysis. Here, we aim to improve the volcanic record for the Southern Hemisphere using a sampling strategy for cryptotephra identification based on coeval deposition of sulphate and microparticles in ice cores from the interior of East Antarctica covering the Mid-to Late Holocene. In total, 15 cryptotephras and one visible horizon were identified and geochemically characterised. Through comparisons to proximal deposits a range of possible sources were isolated for these horizons including the South Sandwich Islands, South Shetland Islands, Victoria Land (Antarctica) and South America. This new tephra framework contributes to the volcanic history of the region by extending the known geographical range of tephra deposition for previously identified events and providing a potential indication of phases of eruptive activity from key sources. Using the tephra-based source attributions and comparison of the timing of the events to a database of sulphur injections from Holocene volcanic eruptions it is possible to refine injection latitudes for some events, which can lead to improved estimates of their radiative forcing potential. The relatively low magnitude of the volcanic stratospheric sulphur injections related to the events in the tephra framework indicates they would have had a limited impact on Southern Hemisphere climate. Further work is required to improve source attributions for some events and/or to determine the magnitude of sulphur injections for individual events during years when coeval eruptions occurred. One limitation of the framework is the dominance of cryptotephra from regional volcanic sources and a lack of tephra from tropical sources, which hampers the refinement of eruption parameters for these large magnitude and often climate-impacting eruptions. This issue could be explored further through increased sampling of these events and/or development of additional analytical techniques for the identification and robust geochemical analysis of glass tephra shards less than 5 μm in diameter. Such investigations could be coupled with model experiments to determine the likelihood that past tropical eruptions deposited glass tephra shards over Antarctica and the potential size range and geographical spread of deposition.Peer reviewe

Molecular diversity of anthracnose pathogen populations associated with UK strawberry production suggests multiple introductions of three different Colletotrichum species.

Fragaria × ananassa (common name: strawberry) is a globally cultivated hybrid species belonging to Rosaceae family. Colletotrichum acutatum sensu lato (s.l.) is considered to be the second most economically important pathogen worldwide affecting strawberries. A collection of 148 Colletotrichum spp. isolates including 67 C. acutatum s.l. isolates associated with the phytosanitary history of UK strawberry production were used to characterize multi-locus genetic variation of this pathogen in the UK, relative to additional reference isolates that represent a worldwide sampling of the diversity of the fungus. The evidence indicates that three different species C. nymphaeae, C. godetiae and C. fioriniae are associated with strawberry production in the UK, which correspond to previously designated genetic groups A2, A4 and A3, respectively. Among these species, 12 distinct haplotypes were identified suggesting multiple introductions into the country. A subset of isolates was also used to compare aggressiveness in causing disease on strawberry plants and fruits. Isolates belonging to C. nymphaeae, C. godetiae and C. fioriniae representative of the UK anthracnose pathogen populations showed variation in their aggressiveness. Among the three species, C. nymphaeae and C. fioriniae appeared to be more aggressive compared to C. godetiae. This study highlights the genetic and pathogenic heterogeneity of the C. acutatum s.l. populations introduced into the UK linked to strawberry production

Adsorption of CO on a Platinum (111) surface - a study within a four-component relativistic density functional approach

We report on results of a theoretical study of the adsorption process of a single carbon oxide molecule on a Platinum (111) surface. A four-component relativistic density functional method was applied to account for a proper description of the strong relativistic effects. A limited number of atoms in the framework of a cluster approach is used to describe the surface. Different adsorption sites are investigated. We found that CO is preferably adsorbed at the top position.Comment: 23 Pages with 4 figure