861 resultados para SAW transducers


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Two decades ago, Canada, Mexico, and the United States created a continental economy. The road to integration from the signing of the North American Free Trade Agreement has not been a smooth one. Along the way, Mexico lived through a currency crisis, a democratic transition, and the rising challenge of Asian manufacturing. Canada stayed united despite surging Quebecois nationalism during the 1990s; since then, it has seen dramatic economic changes with the explosion of hydrocarbon production and a much stronger currency. The United States saw a stock-market bust, the shock of 9/11, and the near-collapse of its financial system. All of these events have transformed the relationships that emerged after NAFTA entered into force in 1994. Given the tremendous changes, one might be skeptical that the circumstances and details of the negotiation and ratification of NAFTA hold lessons for the future of North America. However, the road to NAFTA had its own difficulties, and many of the issues involved in the negotiations underpin today's challenges. NAFTA was conceived at a time of profound change in the international system. When Mexican leaders surveyed the world two decades ago, they saw emerging regional groupings in Europe, Asia, and South America. Faced with a lack of interest or compatibility, they instead doubled down on North America. How did Mexican leaders reconsider their national interests and redefine Mexico's role in the world in light of those transformations? Unpublished Mexican documents from SECOFI, the secretariate most involved in negotiating NAFTA, help illustrate Mexican thinking about its interests and role at that time. Combining those insights with analysis of newly available evidence from U.S. presidential archives, this paper sheds light on the negotiations that concluded two decades ago.

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ISO19156 Observations and Measurements (O&M) provides a standardised framework for organising information about the collection of information about the environment. Here we describe the implementation of a specialisation of O&M for environmental data, the Metadata Objects for Linking Environmental Sciences (MOLES3). MOLES3 provides support for organising information about data, and for user navigation around data holdings. The implementation described here, “CEDA-MOLES”, also supports data management functions for the Centre for Environmental Data Archival, CEDA. The previous iteration of MOLES (MOLES2) saw active use over five years, being replaced by CEDA-MOLES in late 2014. During that period important lessons were learnt both about the information needed, as well as how to design and maintain the necessary information systems. In this paper we review the problems encountered in MOLES2; how and why CEDA-MOLES was developed and engineered; the migration of information holdings from MOLES2 to CEDA-MOLES; and, finally, provide an early assessment of MOLES3 (as implemented in CEDA-MOLES) and its limitations. Key drivers for the MOLES3 development included the necessity for improved data provenance, for further structured information to support ISO19115 discovery metadata export (for EU INSPIRE compliance), and to provide appropriate fixed landing pages for Digital Object Identifiers (DOIs) in the presence of evolving datasets. Key lessons learned included the importance of minimising information structure in free text fields, and the necessity to support as much agility in the information infrastructure as possible without compromising on maintainability both by those using the systems internally and externally (e.g. citing in to the information infrastructure), and those responsible for the systems themselves. The migration itself needed to ensure continuity of service and traceability of archived assets.

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The research reported here is a retrospective case study of the recent (2010) introduction of the Masters in Teaching and Learning (MTL) as a post-graduate level programme of professional development for teachers. It contributes to the debate and research over the past two decades about the impact of post-graduate professional development and appropriate ways of delivering it. The study is located within an extensive body of literature dealing with the importance of the teaching profession with regard to the success of schools and pupils and the impact of professional development on teaching quality and of teaching quality on attainment. A further relevant context is the ongoing tension between the teaching profession and academics on the one hand and government and political actors on the other, in respect of the approaches to professional development and to the control of educational processes. The research questions which inform the study deal with the perspectives of various participants – policy makers, programme directors, coaches and teachers studying for the MTL – on the extent to which the MTL is likely to have an ameliorative effect on teaching and pupil attainment, their experiences of the process of policy development and their experiences as course participants. The study adopts a case study approach which involves elite interviews with those responsible for the development and implementation of the MTL, questionnaires completed by MTL course participants and a comparison group taking a conventional MA and in depth interviews with participants and coaches. The results revealed tensions and difficulties associated with the development of the MTL including uneasy relationships between HE institutions and government agencies, ideas about ‘producer capture’, the relevance of the MBA model and concern over the role of coaches. However, while acknowledging various difficulties and some misconceived expectations they viewed its potential to meet its expressed aims positively, given time. Course participants were positive about their experience of the MTL and felt that it had contributed to many aspects of their professional development. Most saw it as a positive experience despite the variable quality of support from their schools, particularly in the form of the school-based coach the concept of which had been heralded as the bellwether of the MTL. It was striking that the responses of the MTL participants were very similar to those of teachers taking a conventional MA. A finding which would repay further investigation is that while the great majority of course participants felt that the MTL (and the MA) had contributed to their becoming more effective teachers they were much less confident that it had contributed to increased pupil attainment.

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The fifteenth century saw a striking upturn in the number of texts from foreign vernaculars that were translated into Irish. Indeed, one might go so far as to speak in terms of a ‘translation trend’ in Ireland during the mid to late fifteenth century. A notable feature of this trend is that a particularly high number of these Irish translations are of romances; contextual and textual evidence suggests that the original exemplars for many of these translated texts appear to have come from England, though not all of them were necessarily in English. Irish translations of eight romances have survived to the present day: Guy of Warwick; Bevis of Hampton; La Queste de Saint Graal; Fierabras; Caxton’s Recuyell of the Histories of Troie; William of Palerne; the Seven Sages of Rome; and Octavian. This paper addresses two aspects of these texts of particular relevance to romance scholars who do not work within the sphere of Celtic studies. Firstly, it argues that certain aspects of the dissemination and reception of romance in Ireland are quite distinctive. Manuscript and textual evidence suggests that the religious orders, particularly the Franciscans, seem to have played a role in the importation and translation of these narratives. Secondly, examination of the Irish versions of romance tends to bear out an observation made by Flower many years ago, but not pursued by subsequent scholars: ‘texts of an unusual kind were current in Ireland, and it may be that interesting discoveries are to be made here’. Certain narrative features of several of these Irish translations diverge from all the surviving versions of the relevant romance in other languages and may witness to a variant exemplar that has since been lost from its own linguistic corpus.

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The Storms of War, is the first in a trilogy about the de Witt family. The first explores their lives from 1914-1918, as the youngest girl, Celia, sees her perfect world crumble and change. Inspired to write about the wars since Kate visited the trenches in France when she was ten on a school trip. Kate was fascinated by how small they were - and how men could ever live in such places. She really wanted to go into the lives of Germans - the Victorians couldn't get enough of them. Then - almost overnight - they were the enemy and people saw German spies everywhere and the newspapers demanded that all Germans in the country be imprisoned. At the beginning of the book, Rudolf and Verena have four children - and their lives will never be the same again.

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The efficient fertilizer use contend micronutrient depends, also, of the interactions that occur with some nutrients. The objective was to study the interaction of zinc with the excessively nutrient ones in function of the application of different doses and sources of Zn saw seed in the culture of the rice. The experiment was carried through in conditions of vegetation house, in the FCAV/Unesp. The used experimental delineation was entirely cazualized, with three repetitions. The treatments had been five doses: 0; 1,0; 2,0; 4,0 and 8,0 g of Zn for kg of seed; e two zinc sources; sulphate of zinc (22% of Zn) and zinc oxide (50% of Zn). The experimental unit was a translucent polyethylene tray, filled with 5 washed thick sand, where 50 seeds of rice had been sown (to var. Caiapo). To the 30 days after the sowing, effected the cut of the plants, separating them in aerial part and roots. From the results of the dry substance and text of nutrients of the aerial part and root of the rice, the accumulation of the nutrients in the respective agencies of the plants was calculated. Becoming fullfilled it variance analysis and the when necessary unfoldings. It had effect of the interactions in distinguishing way between root and aerial part of rice, with regard to the doses and sources.

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In this study we investigate the effect of a single session of high-intensity contractions on expression of pleiotropic genes and, in particular, those genes associated with metabolism in soleus muscle from electrically stimulated (ES) and contralateral (CL) limbs. The right limbs of male Wistar rats were submitted to contractions by 200-ms trains of electrical stimulation at 100-Hz frequency with pulses of 0.1 ms (voltage 24 3 V) delivered each second for 1 hour. Soleus muscles were isolated 1 hour after contraction, and gene expression was analyzed by a macroarray technique (Atlas Toxicology 1.2 Array; Clontech Laboratories). Electrical stimulation increased expression in 92 genes (16% of the genes present in the membrane). Sixty-six genes were upregulated in both ES and CL soleus muscles, and expression of 26 genes was upregulated in the ES muscle only. The most altered genes were those related to stress response and metabolism. Electrical stimulation also raised expression of transcription factors, translation and posttranslational modification of proteins, ribosomal proteins, and intracellular transducers/effectors/modulators. The results indicate that a single session of electrical stimulation upregulated expression of genes related to metabolism and oxidative stress in soleus muscle from both ES and CL limbs. These findings may indicate an association with tissue hypertrophy and metabolic adaptations induced by physical exercise training not only in the ES but also in the CL non-stimulated muscle, suggesting a cross-education phenomenon. Muscle Nerve 40: 838-846, 2009

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Here we present a status report of the first spherical antenna project equipped with a set of parametric transducers for gravitational detection. The Mario Schenberg, as it is called, started its commissioning phase at the Physics Institute of the University of Sao Paulo, in September 2006, under the full support of FAPESP. We have been testing the three preliminary parametric transducer systems in order to prepare the detector for the next cryogenic run, when it will be calibrated. We are also developing sapphire oscillators that will replace the current ones thereby providing better performance. We also plan to install eight transducers in the near future, six of which are of the two-mode type and arranged according to the truncated icosahedron configuration. The other two, which will be placed close to the sphere equator, will be mechanically non-resonant. In doing so, we want to verify that if the Schenberg antenna can become a wideband gravitational wave detector through the use of an ultra-high sensitivity non-resonant transducer constructed using the recent achievements of nanotechnology.

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The Mario Schenberg gravitational wave detector has started its commissioning phase at the Physics Institute of the University of Sao Paulo. We have collected almost 200 h of data from the instrument in order to check out its behavior and performance. We have also been developing a data acquisition system for it under a VXI System. Such a system is composed of an analog-to-digital converter and a GPS receiver for time synchronization. We have been building the software that controls and sets up the data acquisition. Here we present an overview of the Mario Schenberg detector and its data acquisition system, some results from the first commissioning run and solutions for some problems we have identified.

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Langmuir-Blodgett (LB) and layer-by-layer films (LbL) of a PPV (p-phenylenevinylene) derivative, an azo compound and tetrasulfonated phthalocyanines were successfully employed as transducers in an ""electronic tongue"" system for detecting trace levels of phenolic compounds in water. The choice of the materials was based on their distinct electrical natures, which enabled the array to establish a fingerprint of very similar liquids. Impedance spectroscopy measurements were taken in the frequency range from 10 Hz to 1 MHz, with the data analysed with principal component analysis (PCA). The sensing units were obtained from five-layer LB films of (poly[(2-methoxy-5-n-hexyloxy)-p-phenylenevinylene]), OC(1)OC(18)-PPV (poly(2-methoxy,5-(n-octadecyl)-p-phenylenevinylene)), DR (HEMA-co-DR13MA (poly-(hydroxyethylmethacrylate-co-[4`-[[2-(methacryloyloxy)-ethyl]ethylamino]-2-chloro-4-nitroazobenzene]))) and five-bilayer LbL films of tetrasulfonated metallic phthalocyanines deposited onto gold interdigitated electrodes. The sensors were immersed into phenol, 2-chloro-4-methoxyphenol, 2-chlorophenol and 3-chlorophenol (isomers) solutions at 1 x 10(-9) mol L(-1), with control experiments carried out in ultra pure water. Samples could be distinguished if the principal component analysis (PCA) plots were made with capacitance values taken at 10(3) Hz, which is promising for detection of trace amounts of phenolic pollutants in natural water.

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The concern related to the environmental degradation and to the exhaustion of natural resources has induced the research on biodegradable materials obtained from renewable sources, which involves fundamental properties and general application. In this context, we have fabricated thin films of lignins, which were extracted from sugar cane bagasse via modified organosolv process using ethanol as organic solvent. The films were made using the vacuum thermal evaporation technique (PVD, physical vapor deposition) grown up to 120 nm. The main objective was to explore basic properties such as electrical and surface morphology and the sensing performance of these lignins as transducers. The PVD film growth was monitored via ultraviolet-visible (UV-vis) absorption spectroscopy and quartz crystal microbalance, revealing a linear relationship between absorbance and film thickness. The 120 nm lignin PVD film morphology presented small aggregates spread all over the film surface on the nanometer scale (atomic force microscopy, AFM) and homogeneous on the micrometer scale (optical microscopy). The PVD films were deposited onto Au interdigitated electrode (IDE) for both electrical characterization and sensing experiments. In the case of electrical characterization, current versus voltage (I vs V) dc measurements were carried out for the Au IDE coated with 120 nm lignin PVD film, leading to a conductivity of 3.6 x 10(-10) S/m. Using impedance spectroscopy, also for the Au IDE coated with the 120 nm lignin PVD film, dielectric constant of 8.0, tan delta of 3.9 x 10(-3)) and conductivity of 1.75 x 10(-9) S/m were calculated at 1 kHz. As a proof-of-principle, the application of these lignins as transducers in sensing devices was monitored by both impedance spectroscopy (capacitance vs frequency) and I versus time dc measurements toward aniline vapor (saturated atmosphere). The electrical responses showed that the sensing units are sensible to aniline vapor with the process being reversible. AFM images conducted directly onto the sensing units (Au IDE coated with 120 nm lignin PVD film) before and after the sensing experiments showed a decrease in the PVD film roughness from 5.8 to 3.2 nm after exposing to aniline.

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This essay is an ideographic study over the capacity of high school students to use the Internet with source criticism, and their attitudes towards this media. It’s a qualitative study whose main purpose is to seek out how the students reflect upon the problems facing them when searching facts and information over the internet.The focus group is six 18 year old high school students, who are studying in a normal sized town in the middle of Sweden, and are about to finish their studies in the program for social sciences. The study was made through interviews, one on one with the students,The results of the analysis have shown that even if students not necessarily use a pre meditated method when searching for information over the internet, they do have a basic understanding of the matter, especially concerning the nature of the source, who published it and why. Not all students made any thorough comparison with other, already established media, such as TV or books, but the analysis made it clear that they more or less deliberately saw the established media as more trustworthy in general. Individuals publishing on the internet, such as bloggers and Wikipedia, are seen with the utmost skepticism while public institutions such as universities and public service TV, are generally trusted as being honest and objective, also when publishing on the internet.

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Vid trädfällning med motorsåg sparar man en så kallad brytmån som skall fungera som ett gång¬järn när trädet fälls. Om brytmånen går av tidigt finns en risk att trädet faller okontrolle¬rat. De rekommendationer som finns säger att brytmånens bredd skall göras proportionell mot trädets diameter. Genom att teoretiskt och praktiskt undersöka vilka krafter brytmånen utsätts för och vad den håller för har det varit möjligt att dra vissa slutsatser om hur en bra brytmån skall se ut. Ett viktigt resultat är att en bred brytmån (över 30-40 mm) är mycket trög att böja och inte fungerar i det avseendet att den går av redan vid små böjningar. Teoretiska be¬räkningar och praktiska försök visar att en relativt smal brytmån håller för belastningen vid rakt motlut även på stora träd. Som ny rekommendationen föreslås att brytmånens bredd inte bör vara mer än 30 mm. Av försöken kan man också dra slutsatsen att frusen ved är stel och brister tidigt, varför svår¬fällda träd inte bör fällas när veden är fryst.A felling hinge is used when felling trees by help of chain saw. If the hinge breaks early in the fall of the tree there is a great risk that the tree will fall without control. Present recommenda¬tions in Sweden say that the thickness of the felling hinge shall be made in proportion to the stem diameter. By use of theoretical and practical examinations of the forces stressing the felling hinge, and the strength of the wood itself, it has been possible to draw conclusions regarding the correct design of a felling hinge. One important result is that a thick felling hinge (over 30-40 mm) is very hard to bend and does not work well as it looses most of its strength already at a small forward bending angel. Theoretical calculations and practical tests show that a relatively narrow felling hinge will manage very well the forces when felling trees with lean opposite to the felling direction even for large trees. Our new recommendation is that the thickness of the felling hinge in normal Swedish conditions should not exceed 30 mm. Through the studies it can also be seen that frozen, brittle wood breaks at small bending angels. For that reason particularly difficult trees not should be felled when the wood is frozen.

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The objective with this study has been to build general models of the mechanics in tree felling with chain-saw and to compare felling torque for different tools. The theoretical models are completed and validated with a comparative study. The study includes a great number of felling tools of which some are used with different methods. Felling torque was measured using a naturally like measuring arrangement where a tree is cut at about 3.7 m height and then anchored with a dynamometer to a tree opposite to the felling direction. Notch and felling cut was made as ordinary with exception that the hinge was made extra thin to reduce bending resistance. The tree was consequently not felled during the trials and several combinations of felling tools and individuals could be used on the same tree.The results show big differences between tools, methods and persons. The differences were, however, not general, but could vary depending on conditions (first of all tree diameters). Tools and methods that push or pull on the stem are little affected by the size of the tree, while tools that press on the stump are very much dependent of a large stump-diameter. Hand force asserted on a simple pole is consequently a powerful tool on small trees. For trees of medium size there are several alternative methods with different sizes and brands of felling levers and wedges. Larger and more ungainly tools and methods like tree pusher, winch, etc. develop very high felling torque on all tree sizes. On large trees also the felling wedge and especially the use of several wedges together develop very high felling torque.

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SammanfattningHögskolan Dalarna har i samarbete med Skogsägarna Mellanskog, Naturbränsle i Mellan¬sverige AB och GDE-Net genomfört studier på en ny metod för uttag av skogsbränsle från slutavverkningar. Metoden går ut på att timmer tas ut som enda rundvirkessortiment. Resten av trädet, samt klenare träd som inte håller timmerdimension, tas ut som ett bränslesortiment. Metoden har jämförts med en konventionell slutavverkning med uttag av timmer, massaved och GROT-flis.Enligt genomförda försök skulle en avverkning enligt den nya metoden (långa toppar) ge ett högre drivningsnetto och drygt dubbelt så mycket bränsleflis som en konventionell avverk¬ning. En anledning till det högre drivningsnettot är att kostnaden för flisning blir lägre än vid flisning av GROT och att flisen betalas bättre än GROT-flis. Resultaten är beroende av de faktiska beståndsförutsättningarna och gällande prisrelationer mellan massaved och bränsle¬flis.Faktorer som har en positiv inverkan på drivningsnettot vid uttag av ”långa toppar” är t.ex. stora uttagsvolymer och korta terrängtransportavstånd samt bestånd med en hög andel virke av låg kvalitet eller udda sortiment som betalas dåligt på rundvirkesmarknaden.SummaryIn Sweden forest energy from final felling is traditionally harvested as logging residues after harvesting of timber (saw logs) and pulpwood, but depending on the market situation other methods with higher yield of forest energy might be of interest. Dalarna University has study a new method called “Undelimbed long tops” where only saw timber was taken out as an industrial assortment. The rest of the trees and smaller trees that don’t hold timber dimensions was left intact on the clear-felled area and been chipped later on. The study was done in different stands with some different conditions. The results have been compared with the traditional method for final felling. The surplus (forest owners net income) was higher in almost all stands when the method with “undelimbed long tops” was used, compared to the traditional method for taking out forest energy, and the volume of chips was more than doubled. A reason for the higher income from long tops is that the costs for chipping is lower and the prize of chips is higher compared to chips from logging residues. Other reason is that forest owners will not be paid for wasted pulpwood, but will be fully paid for the chips from such pulpwood. Factors that will have a positive influence on the ULT-method are for example large logging volumes and short distance between the logging area and the landing, different kinds of price reductions on pulpwood and large volumes of rotten wood or low paid industrial assortments.