991 resultados para Field of science


Relevância:

100.00% 100.00%

Publicador:

Resumo:

The ability of large-grain (RE)Ba2Cu3O7-δ ((RE)BCO; RE = rare earth) bulk superconductors to trap magnetic fields is determined by their critical current. With high trapped fields, however, bulk samples are subject to a relatively large Lorentz force, and their performance is limited primarily by their tensile strength. Consequently, sample reinforcement is the key to performance improvement in these technologically important materials. In this work, we report a trapped field of 17.6 T, the largest reported to date, in a stack of two silver-doped GdBCO superconducting bulk samples, each 25 mm in diameter, fabricated by top-seeded melt growth and reinforced with shrink-fit stainless steel. This sample preparation technique has the advantage of being relatively straightforward and inexpensive to implement, and offers the prospect of easy access to portable, high magnetic fields without any requirement for a sustaining current source. © 2014 IOP Publishing Ltd.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Since the international financial and food crisis that started in 2008, strong emphasis has been made on the importance of Genetically Modified Organisms (GMOs) (or “transgenics”) under the claim that they could contribute to increase food productivity at a global level, as the world population is predicted to reach 9.1 billion in the year 2050 and food demand is predicted to increase by as much as 50% by 2030. GMOs are now at the forefront of the debates and struggles of different actors. Within civil society actors, it is possible to observe multiple, and sometime, conflicting roles. The role of international social movements and international NGOs in the GMO field of struggle is increasingly relevant. However, while many of these international civil society actors oppose this type of technological developments (alleging, for instance, environmental, health and even social harms), others have been reportedly cooperating with multinational corporations, retailers, and the biotechnology industry to promote GMOs. In this thesis research, I focus on analysing the role of “international civil society” in the GMO field of struggle by asking: “what are the organizing strategies of international civil society actors, such as NGOs and social movements, in GMO governance as a field of struggle?” To do so, I adopt a neo-Gramscian discourse approach based on the studies of Laclau and Mouffe. This theoretical approach affirms that in a particular hegemonic regime there are contingent alliances and forces that overpass the spheres of the state and the economy, while civil society actors can be seen as a “glue” to the way hegemony functions. Civil society is then the site where hegemony is consented, reproduced, sustained, channelled, but also where counter-hegemonic and emancipatory forces can emerge. Considering the importance of civil society actors in the construction of hegemony, I also discuss some important theories around them. The research combines, on the one hand, 36 in-depth interviews with a range of key civil society actors and scientists representing the GMO field of struggle in Brazil (19) and the UK (17), and, on the other hand, direct observations of two events: Rio+20 in Rio de Janeiro in 2012, and the first March Against Monsanto in London in 2013. A brief overview of the GMO field of struggle, from its beginning and especially focusing in the 1990s when the process of hegemonic formation became clearer, serves as the basis to map who are the main actors in this field, how resource mobilization works, how political opportunities (“historical contingencies”) are discovered and exploited, which are the main discourses (“science” and “sustainability” - articulated by “biodiversity preservation”, “food security” and “ecological agriculture”) articulated among the actors to construct a collective identity in order to attract new potential allies around “GMOs” (“nodal point”), and which are the institutions and international regulations within these processes that enable hegemony to emerge in meaningful and durable hegemonic links. This mapping indicates that that the main strategies applied by the international civil society actors are influenced by two central historical contingencies in the GMO field of struggle: 1) First Multi-stakeholder Historical Contingency; and 2) “Supposed” Hegemony Stability. These two types of historical contingency in the GMO field of struggle encompass deeper hegemonic articulations and, because of that, they induce international civil society actors to rethink the way they articulate and position themselves within the field. Therefore, depending on one of those moments, they will apply one specific strategy of discourse articulation, such as: introducing a new discourse in hegemony articulation to capture the attention of the public and of institutions; endorsing new plural demands; increasing collective visibility; facilitating material articulations; sharing a common enemy identity; or spreading new ideological elements among the actors in the field of struggle.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Austenitic stainless steel presents phase changes caused by heat treatment and welding processes. Because it represents a problem in the design of high-homogeneity magnets, we have been studying the magnetic properties of Ti alloys for their use instead of stainless steel as structural material for superconducting magnet construction. In this work, we present the comparative study of the influence of magnetic properties of steel and Ti alloys on the magnetic-field homogeneity of a superconducting coil through numerical calculation using the measured magnetic properties. © 2001 Elsevier Science B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

To assess the influence of anatomic location on the relationship between computed tomography (CT) number and X-ray attenuation in limited and medium field-of-view (FOV) scans. Materials and Methods Tubes containing solutions with different concentrations of K2HPO4 were placed in the tooth sockets of a human head phantom. Cone-beam computed tomography (CBCT) scans were acquired, and CT numbers of the K2HPO4 solutions were measured. The relationship between CT number and K2HPO4 concentration was examined by linear regression analyses. Then, the variation in CT number according to anatomic location was examined. Results The relationship between K2HPO4 concentration and CT number was strongly linear. The slopes of the linear regressions for the limited FOVs were almost 2-fold lower than those for the medium FOVs. The absolute CT number differed between imaging protocols and anatomic locations. Conclusion There is a strong linear relationship between X-ray attenuation and CT number. The specific imaging protocol and anatomic location of the object strongly influence this relationship.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We find the first nonlinear correction to the field produced by a static charge at rest in a background constant magnetic field. It is quadratic in the charge and purely magnetic. The third-rank polarization tensor-the nonlinear response function-is written within the local approximation of the effective action in an otherwise model-and approximation-independent way within any P-invariant nonlinear electrodynamics, QED included. DOI: 10.1103/PhysRevD.86.125028

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We prove that the simple Lie algebras constructed by G. Jurman (2004) in 121 are isomorphic to Hamiltonian algebras. As a corollary we answer all questions formulated in G. Jurman (2004) [2] about isomorphisms of these algebras. (C) 2012 Elsevier Inc. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

For as far back as human history can be traced, mankind has questioned what it means to be human. One of the most common approaches throughout Western culture's intellectual tradition in attempts to answering this question has been to compare humans with or against other animals. I argue that it was not until Charles Darwin's publication of The Descent of Man and Selection in Relation to Sex (1871) that Western culture was forced to seriously consider human identity in relation to the human/ nonhuman primate line. Since no thinker prior to Charles Darwin had caused such an identity crisis in Western thought, this interdisciplinary analysis of the history of how the human/ nonhuman primate line has been understood focuses on the reciprocal relationship of popular culture and scientific representations from 1871 to the Human Genome Consortium in 2000. Focusing on the concept coined as the "Darwin-Müller debate," representations of the human/ nonhuman primate line are traced through themes of language, intelligence, and claims of variation throughout the popular texts: Descent of Man, The Jungle Books (1894), Tarzan of the Apes (1914), and Planet of the Apes (1963). Additional themes such as the nature versus nurture debate and other comparative phenotypic attributes commonly used for comparison between man and apes are also analyzed. Such popular culture representations are compared with related or influential scientific research during the respective time period of each text to shed light on the reciprocal nature of Western intellectual tradition, popular notions of the human/ nonhuman primate line, and the development of the field of primatology. Ultimately this thesis shows that the Darwin-Müller debate is indeterminable, and such a lack of resolution makes man uncomfortable. Man's unsettled response and desire for self-knowledge further facilitates a continued search for answers to human identity. As the Human Genome Project has led to the rise of new debates, and primate research has become less anthropocentric over time, the mysteries of man's future have become more concerning than the questions of our past. The human/ nonhuman primate line is reduced to a 1% difference, and new debates have begun to overshadow the Darwin-Müller debate. In conclusion, I argue that human identity is best represented through the metaphor of evolution: both have an unknown beginning, both have an indeterminable future with no definite end, and like a species under the influence of evolution, what it means to be human is a constant, indeterminable process of change.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The concept of feminist metistic resilience postulates that the voiceless, the marginalized and the minority in societies employ strategies in order to turn tables in their favor. This study presents a qualitative analysis of how women, considered to be the minority, negotiate their situatedness in science fields in order to effect change in their lives or that of the society and why they become successful. By “situatedness,” I refer to the everyday life of women as they live and encounter people, society and culture, especially, the life of women who have transcended the culturally stipulated role of women and are excelling in a male dominated field. The study, in different dimensions, conceptualizes the reason for the fewer number of women in science; looks at how scientific methods and practices inhibit the development of women in science; and, finally, interrogates the question of objectivity in science. It becomes apparent, through feminist metistic resilience, that women become successful when they accept conventional practices in scientific arrangements and structures. They accept the practices by embracing and not questioning structures and arrangements that have shaped the field of science and by shifting shapes and assuming different forms in order to adapt to conditions they encounter. Apart from adapting and shape shifting, the women also become successful through environmental and social influences. My analysis suggests that more women can be encouraged to pursue science when women practicing science begin to question structures and arrangements that have shaped the practice of science over the centuries. The overall findings of the research provide implications for policy makers, educators and feminist researchers.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

In absence of basic canine hip biomechanics, a specific, consequent three dimensional concept to evaluate the coxofemoral joint was developed for the dog. With the help of a new method to radiologically demonstrate the hip in a physiological standing position several new clinically relevant aspects could be further investigated. For example the breed specific anatomical differences in the hip, and dynamics and the background on "iatrogenic luxations" in HD diagnostics could be shown. The caudal luxation and the growth abnormalities of the hip and their consequences on the whole leg (antetorsion syndrome) as a consequence of inadequate breeding could be demonstrated.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The main objective of this course, conducted by Jóvenes Nucleares (Spanish Young Generation in Nuclear, JJNN), a non-profit organization that depends on the Spanish Nuclear Society (SNE) is to pass on basic knowledge about Science and Nuclear Technology to the general public, mostly students and introduce them to its most relevant points. The purposes of this course are to provide general information, to answer the most common questions about Nuclear Energy and to motivate the young students to start a career in nuclear. Therefore, it is directed mainly to high school and university students, but also to general people that wants to learn about the key issues of such an important matter in our society. Anybody could attend the course, as no specific scientific education is required. The course is done at least once a year, during the Annual Meeting of the Spanish Nuclear Society, which takes place in a different Spanish city each time. The course is done also to whichever university or institution that asks for it to JJNN, with the only limit of the presenter´s availability. The course is divided into the following chapters: Physical nuclear and radiation principles, Nuclear power plants, Nuclear safety, Nuclear fuel, Radioactive waste, Decommission of nuclear facilities, Future nuclear power plants, Other uses of nuclear technology, Nuclear energy, climate change and sustainable development. The course is divided into 15 minutes lessons on the above topics, imparted by young professionals, experts in the field that belongs either to the Spanish Young Generation in Nuclear, either to companies and institutions related with nuclear energy. At the end of the course, a 200 pages book with the contents of the course is handed to every member of the audience. This book is also distributed in other course editions at high schools and universities in order to promote the scientific dissemination of the Nuclear Technology. As an extra motivation, JJNN delivers a course certificate to the assistants. At the end of the last edition course, in Santiago de Compostela, the assistants were asked to provide a feedback about it. Some really interesting lessons were learned, that will be very useful to improve next editions of the course. As a general conclusion of the courses it can be said that many of the students that have assisted to the course have increased their motivation in the nuclear field, and hopefully it will help the young talents to choose the nuclear field to develop their careers

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This article presents the model of a multi-agent system (SMAF), which objectives are the input of fuzzy incidents as the human experts express them with different severities degrees and the further search and suggestion of solutions. The solutions will be later confirm or not by the users. This model was designed, implemented and tested in the telecommunications field, with heterogeneous agents in a cooperative model. In the design, different abstract levels where considered, according to the agents? objectives, their ways to carry it out and the environment in which they act. Each agent is modeled with different spectrum of the knowledge base

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Teamwork, is one of the abilities that today is highly valued in the professional arena with a great importance for various personal and interpersonal skills associated with it. In this context, the Technical University of Madrid, is developing a coordinated educational innovation project, which main objective is to develop methodological and assessment tools for the acquisition of personal skills necessary to improve the employability of graduates and their skills for project management. Within this context, this paper proposes a methodology composed of various activities and indicators, as well as specific assessment instruments linked to the teamwork competence. Through a series of systematic steps it was allowed the design of an instrument and construction of a scale for measuring the competence of teamwork. The practical application of the methodology has been carried out in Projects lectures from different Schools of Engineering at the Technical University of Madrid, which results are presented in this document as a pilot experience. Results show the various aspects and methods that teachers should consider in evaluating the competence of the work, including analysis of the quality of results, through reliability and construct validity. On the other hand, show the advantages of applying this methodology in the field of project management teaching.