1,721,300 research outputs found
Strong coupling theory and the Josephson current into proximity high Tc junctions
No full textThe correlation between the order parameter and the energy gap is studied. Josephson junctions containing proximity systems are described within the framework of the strong coupling theory. The value of the current is affected by the difference between the order parameter at zero frequency and the energy gap. The proximity effect leads to depression of the Josephson current for the high-critical-temperature junctions
Spontaneous magnetic moments in YBa2Cu3O7-x thin films
No full textWe have observed spontaneous magnetic moments with random signs in c-axis-oriented thin films of the high-Tc cuprate superconductor YBa2Cu3O7-d , imaged with a scanning superconducting quantum interference device microscope. These moments arise when the samples become superconducting, and appear to be associated with nonferromagnetic defects in the films. In contrast with granular high-Tc samples, which also show spontaneous moments with random signs, the present samples shield diamagnetically
EDUCATING FOR DIVERSITY. A CONSTRUCTIVIST PEDAGOGY FOR INTERCULTURAL EDUCATION
No full textIn today’s multicultural and complex society, training on diversity issues becomes an indispensable foundation for the full development of the skills needed to meet today’s challenges. Within formal and non formal educational contexts, first and foremost schools, there is an increasing need for professionalism capable of managing and initiating multicultural practices. In other words, it is a matter of satisfying differentiated needs that require qualified and up to date training. In this sense, the multicultural orientation in the educational context aims at defining an intentional project to promote dialogue and cultural exchange for all.
In this way, diversities of all kinds, cultural, gender, social class, become a privileged point of view of educational processes, offering the opportunity for each person to develop from what they really are. Multicultural education, in fact, emerges from many quarters as a tool for reflection and educational action, not only for school workers, but for all those who find themselves living in a “society of interdependencies”.
Multiculturality calls us, therefore, to make a choice of meaning, to develop a critical ethnocentrism and to work on building bridges and roads, in search of a possible dialogue and new co-constructed identities. Multicultural education, as extensively set out in this contribution, concerns everyone, and only acquires meaning and reason to exist within broad frameworks that stem from the conception of dignity and respect for all individuals, with a view to the develop- ment of equal opportunities for choice and personal development and wellbeing.
In line with this perspective, the volume has been divided into two parts. The first part of the text is dedicated to an indepth examination of the concept of multiculturalism from a perspective that tends to analyse it, clarifying theories, concepts, and terms, useful to create a lexicon, a common, scientifically supported language that facilitates understanding.
The second part, on the other hand, aims to clarify how, starting with a correct approach to educational work in schools, one can hope to spread an increasingly necessary “culture of diversity”, which must be properly designed and constructed.
The importance of acquiring knowledge and skills useful for intercultural dialogue is also emphasised, not only as a training objective for students, but as a relevant element for teaching professionalism. From this perspective, the Italian school is called upon to choose to adopt the multicultural perspective, i.e. the promotion of dialogue and confrontation between cultures, for all pupils and at all levels: teaching, curricula, disciplines, relationships, classroom life.
Opting for a multicultural perspective means, therefore, not limiting oneself to mere integration strategies for immigrant pupils, nor to special compensatory measures. Instead, it is a matter of taking diver- sity as a paradigm of the very identity of the school in pluralism, as an opportunity to open the entire system to all differences. Becoming aware of the relativity of cultures, in fact, does not mean arriving at an absolute relativism, which postulates neutrality towards them and thus prevents their relations. Multicultural strategies avoid separating individuals into autonomous and impermeable cultural worlds, instead promoting confrontation, dialogue, and even mutual transformation, in order to make coexistence possible and address the resulting conflicts. Within these trajectories of meaning, multicultural education and training can take new steps to achieve a truly democratic society, representing an important space for personal and social growth and emancipation.
This contribution therefore aims to explore the topic of multicultural education through the integration of theoretical aspects, practical experience, and empirical research. These aspects, which are clos- er to the observable reality, allow for a comprehensive and in-depth analysis with respect to the issues of multiculturalism and education
Variation of the Josephson current with carrier concentration in the barrier
No full textA phenomenological investigation of the de Josephson current in superconductor- (S-) normal-metal-(N) [semiconductor- (Sm-)] superconductor junctions is carried out as a function of the carrier concentration in the barrier. The occurrence of a nonmonotonic dependence of the Josephson current on the carrier concentration is predicted within some limits. This study suggests that in S-N- (Sm-) S structures there is an optimum carrier concentration range which gives the maximum value of the Josephson current I-C and the junction parameter l(C)R(N)
Evaluating the physiological conditions and biomechanics of wheelchair basketball players: A comprehensive study
No full textWeak links in high critical temperature superconductors
No full textThe traditional distinction between tunnel and highly transmissive barriers does not currently hold for high critical temperature superconducting Josephson junctions, both because of complicated materials issues and the intrinsic properties of high temperature superconductors (HTS). An intermediate regime, typical of both artificial superconductor– barrier–superconductor structures and of grain boundaries, spans several orders of magnitude in the critical current density and specific resistivity. The physics taking place at HTS surfaces and interfaces is rich, primarily because of phenomena associated with d wave order parameter (OP) symmetry. These phenomena include Andreev bound states, the presence of the second harmonic in the critical current versus phase relation, a doubly degenerate state, time reversal symmetry breaking and the possible presence of an imaginary component of the OP. All these effects are regulated by a series of transport mechanisms, whose rules of interplay and relative activation are unknown. Some transport mechanisms probably have common roots, which are not completely clear and possibly related to the intrinsic nature of high-TC superconductivity. The d-wave OP symmetry gives unique properties to HTS weak links, which do not have any analogy with systems based on other superconductors. Even if the HTS structures are not optimal, compared with low critical temperature superconductor Josephson junctions, the state of the art allows the realization of weak links with unexpectedly high quality quantum properties, which open interesting perspectives for the future. The observation of macroscopic quantum tunnelling and the qubit proposals represent significant achievements in this direction. In this review we attempt to encompass all the above aspects, attached to a solid experimental basis of junction concepts and basic properties, along with a flexible phenomenological background, which collects ideas on the Josephson effect in the presence of d-wave pairing for different types of barriers
Andreev reflection in layered structures: implications for high TC grain boundary Josephson junctions
Full text linkAndreev reflection is investigated in layered anisotropic normal-metal–superconductor ~N/S! systems in the
case of an energy gap (D) in S not negligible with respect to the Fermi energy (EF), as it probably occurs with
high critical temperature superconductors ~HTSC’s!. We find that in these limits retroreflectivity, which is a
fundamental feature of Andreev reflection, is broken modifying sensitively transport across S/N interfaces. We
discuss the consequences for supercurrents in HTSC Josephson junctions and for the midgap states in S-N
contacts
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