1,566 research outputs found
Spin-orbit effects on the Larmor dispersion relation in GaAs quantum wells
We have studied the relevance of spin-orbit coupling to the dispersion 00009
relation of the Larmor resonance observed in inelastic light scattering and
electron-spin resonance experiments on GaAs quantum wells. We show that the
spin-orbit interaction, here described by a sum of Dresselhaus and
Bychkov-Rashba terms, couples Zeeman and spin-density excitations. We have
evaluated its contribution to the spin splitting as a function of the magnetic
field , and have found that in the small limit, the spin-orbit
interaction does not contribute to the spin splitting, whereas at high magnetic
fields it yields a independent contribution to the spin splitting given by
, with being the intensity of the
Bychkov-Rashba and Dresselhaus spin-orbit terms.Comment: To be published in Physical Review
Zero modes on cosmic strings in an external magnetic field
A classical analysis suggests that an external magnetic field can cause
trajectories of charge carriers on a superconducting domain wall or cosmic
string to bend, thus expelling charge carriers with energy above the mass
threshold into the bulk. We study this process by solving the Dirac equation
for a fermion of mass and charge , in the background of a domain wall
and a magnetic field of strength . We find that the modes of the charge
carriers get shifted into the bulk, in agreement with classical expectations.
However the dispersion relation for the zero modes changes dramatically --
instead of the usual linear dispersion relation, , the new
dispersion relation is well fit by where
for a thin wall in the weak field limit, and for a thick
wall of width . This result shows that the energy of the charge carriers on
the domain wall remains below the threshold for expulsion even in the presence
of an external magnetic field. If charge carriers are expelled due to an
additional perturbation, they are most likely to be ejected at the threshold
energy .Comment: 9 pages, 4 figure
Spin-orbit effects in GaAs quantum wells: Interplay between Rashba, Dresselhaus, and Zeeman interactions
The interplay between Rashba, Dresselhaus and Zeeman interactions in a
quantum well submitted to an external magnetic field is studied by means of an
accurate analytical solution of the Hamiltonian, including electron-electron
interactions in a sum rule approach. This solution allows to discuss the
influence of the spin-orbit coupling on some relevant quantities that have been
measured in inelastic light scattering and electron-spin resonance experiments
on quantum wells. In particular, we have evaluated the spin-orbit contribution
to the spin splitting of the Landau levels and to the splitting of charge- and
spin-density excitations. We also discuss how the spin-orbit effects change if
the applied magnetic field is tilted with respect to the direction
perpendicular to the quantum well.Comment: 26 pages (with 3 figures included
Logics of formal inconsistency arising from systems of fuzzy logic
This article proposes the meeting of fuzzy logic with paraconsistency in a very precise and foundational way. Specifically, in
this article we introduce expansions of the fuzzy logic MTL by means of primitive operators for consistency and inconsistency
in the style of the so-called Logics of Formal Inconsistency (LFIs). The main novelty of the present approach is the definition
of postulates for this type of operators over MTL-algebras, leading to the definition and axiomatization of a family of logics,
expansions of MTL, whose degree-preserving counterpart are paraconsistent and moreover LFIs.The authors have been partially supported by the FP7-PEOPLE-2009-IRSES project MaToMUVI (PIRSES-GA-2009-247584). Coniglio was also supported by FAPESP (Thematic Project LogCons 2010/51038-0), and by a research grant from
CNPq (PQ 305237/2011-0). Esteva and Godo also acknowledge partial support by the MINECO project TIN2012-39348-C02-01Peer Reviewe
On the set of intermediate logics between the truth- and degree-preserving Łukasiewicz logics
The aim of this article is to explore the class of intermediate logics between the truth-preserving Łukasiewicz logic Ł and its degree-preserving companion Ł≤. From a syntactical point of view, we introduce some families of inference rules (that generalize the explosion rule) that are admissible in Ł≤ and derivable in L and we characterize the corresponding intermediate logics. From a semantical point of view, we first consider the family of logics characterized by matrices defined by lattice filters in [0,1], but we show there are intermediate logics falling outside this family. Finally, we study the case of finite-valued Lukasiewicz logics where we axiomatize a large family of intermediate logics defined by families of matrices (A,F) such that A is a finite MV-algebra and F is a lattice filter.The authors have been partially supported by the FP7-PEOPLE-2009-IRSES project MaToMUVI (PIRSES-GA-2009-247584). Coniglio was also supported by FAPESP (Thematic Project LogCons 2010/51038-0), and by a research grant from CNPq
(PQ 308524/2014-4). Esteva and Godo also acknowledge partial support by the MINECO project TIN2012-39348-C02-01.Peer Reviewe
On Logics of Formal Inconsistency and Fuzzy Logics
Ver abstractThe authors have been partially supported by the FP7-PEOPLE-2009-IRSES project MaToMUVI (PIRSES-GA-2009-247584). Coniglio was also supported by FAPESP (Thematic Project LogCons 2010/51038-0), and
by a research grant from CNPq (PQ 305237/2011-0). Esteva and Godo also acknowledge partial support by the MINECO project TIN2012-39348-C02-01Peer Reviewe
Present i futur de les cèl·lules dendrítiques
El sistema immunitari és una de les estructures més complexes del cos. Aquesta complexitat no és supèrflua, sinó que és totalment necessària per fer totes les tasques complicades a les quals fa front, com és el reconeixement i eliminació d'un ampli espectre de microorganismes i patògens, la detecció i destrucció de lesions oncològiques en un ampli rang de teixits i, mentre porta a terme aquestes tasques, el manteniment de la tolerància perifèrica per mitjà de la supressió de respostes perjudicials autoreactives dirigides contra teixits sans. Des del seu descobriment, fet per R. Steinman i col·laboradors fa uns quaranta anys, les cèl·lules dendrítiques (CD) s'han situat com uns elements clau en la direcció del sistema immunitari per portar a terme les seves tasques. En aquesta revisió mostrem una visió general sobre la biologia de les CD, els coneixements que se'n tenen fins al moment, les seves possibles aplicacions terapèutiques per al tractament de malalties i les incògnites que encara queden per respondre en investigacions futures.The immune system is probably one of the most complex cellular organisations in the body. Its complexity is not superfluous; rather, it is necessary to fulfil the complicated purpose of the immune system, namely: recognition of the diverse repertoire of microorganisms and pathogens; the detection of neoplastic lesions originating from a range of tissues; and, while executing these tasks, the maintenance of peripheral tolerance by suppressing detrimental responses against healthy tissues. Since they were discovered by R. Steinman and co. nearly forty years ago, dendritic cells (DCs) have emerged to be critical players in conducting the immune response to fulfil these roles. Here, we provide a general overview of DCs, what we currently know, their possible therapeutic applications and the questions that remain unanswered for future research
Targeted-pig trial on safety and immunogenicity of serum-derived extracellular vesicles enriched fractions obtained from Porcine Respiratory and Reproductive virus infections
The Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is the etiological agent of one of the
most important swine diseases with a significant economic burden worldwide. Unfortunately, available
vaccines are partially effective highlighting the need of novel approaches. Previously, antigenic viral
proteins were described in serum-derived extracellular vesicles (EVs) from pigs previously infected with
PRRSV. Here, a targeted-pig trial was designed to determine the safety and immunogenicity of such
extracellular vesicles enriched fractions. Our results showed that immunizations with EV-enriched
fractions from convalescence animals in combination with montanide is safe and free of virus as
immunizations with up-to two milligrams of EV-enriched fractions did not induce clinical symptoms,
adverse effects and detectable viral replication. In addition, this vaccine formulation was able to elicit
specific humoral IgG immune response in vaccinated animals, albeit variably. Noticeably, sera from
vaccinated animals was diagnosed negative when tested for PRRSV using a commercial ELISA test;
thus, indicating that this new approach differentiates vaccinated from infected animals. Lastly, after
priming animals with EV-enriched fractions from sera of convalescence animals and boosting them with
synthetic viral peptides identified by mass spectrometry, a distinctive high and specific IFN-γ response
was elicited. Altogether, our data strongly suggest the use of serum EV-enriched fractions as a novel
vaccine strategy against PRRSV.Anti-CD9, Anti-CD63 and anti-CD81 antibodies were kindly donated by Francisco Sánchez-Madrid and Maria Yañez-Mo, Hospital de la Princesa, Madrid, Spain. The authors wish to particularly thank Glòria Abella for her collaboration in conducting the field study and to Marta Alcobé, Miriam Moron Font and Paula Crego Mendez for technical assistance. This study received support from Innovex Therapeutics S.L., Pinsos del Segre SA, Granja Casanyé, Grup de Sanejament Porci (GSP, Lleida, Spain) and the FEDER project (COMRDI16-1-0035-03). Sergio Montanter-Tarbes is an industrial doctorate awarded by the Government of Catalonia, Spain (No. 2014 DI 044). ISGlobal and IGTP are members of the CERCA Programme, Generalitat de Catalunya
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