77 research outputs found
Nonlocal long-range synchronization of planar Josephson junction arrays
We study arrays of planar Nb Josephson junctions with contacts to
intermediate electrodes, which allow measurements of individual junctions and,
thus, provide an insight into intricate array dynamics. We observe a robust
phase-locking of arrays, despite a significant inter-junction separation.
Several unusual phenomena are reported, such as a bi-stable critical current
with re-entrant superconductivity upon switching of nearby junctions; and
incorrect Shapiro steps, occurring at mixing frequencies between the external
RF radiation and the internal Josephson frequency in nearby junctions. Our
results reveal a surprisingly strong and long-range inter-junction interaction.
It is attributed to nonlocality of planar junction electrodynamics, caused by
the long-range spreading of stray electromagnetic fields. The nonlocality
greatly enhances the high-frequency interjunction coupling and enables
large-scale synchronization. Therefore, we conclude that planar geometry is
advantageous for realization of coherent Josephson electronics.Comment: 8 pages, 5 figure
(Contravariant) Koszul duality for DG algebras
A DG algebras over a field with connected and
has a unique up to isomorphism DG module with . It is proved
that if is degreewise finite, then RHom_A(?,K): D^{df}_{+}(A)^{op}
\equiv D_{df}^{+}}(RHom_A(K,K)) is an exact equivalence of derived categories
of DG modules with degreewise finite-dimensional homology. It induces an
equivalences of and the category of perfect DG
-modules, and vice-versa. Corresponding statements are proved also
when is simply connected and .Comment: 33 page
Schreier rewriting beyond the classical setting
Using actions of free monoids and free associative algebras, we establish
some Schreier-type formulas involving the ranks of actions and the ranks of
subactions in free actions or Grassmann-type relations for the ranks of
intersections of subactions of free actions. The coset action of the free group
is used to establish the generalization of the Schreier formula to the case of
subgroups of infinite index. We also study and apply large modules over free
associative algebras in the spirit of the paper Olshanskii, A. Yu.; Osin, D.V.,
Large groups and their periodic quotients, Proc. Amer. Math. Soc., 136 (2008),
753 - 759.Comment: 17 page
Nebuliser therapy in the intensive care unit
The relationship between identity, lived experience, sexual practices and the language through which these are conveyed has been widely debated in sexuality literature. For example, ‘coming out’ has famously been conceptualised as a ‘speech act’ (Sedgwick 1990) and as a collective narrative (Plummer 1995), while a growing concern for individuals’ diverse identifications in relations to their sexual and gender practices has produced interesting research focusing on linguistic practices among LGBT-identified individuals (Leap 1995; Kulick 2000; Cameron and Kulick 2006; Farqhar 2000). While an explicit focus on language remains marginal to literature on sexualities (Kulick 2000), issue of language use and translation are seldom explicitly addressed in the growing literature on intersectionality. Yet intersectional perspectives ‘reject the separability of analytical and identity categories’ (McCall 2005:1771), and therefore have an implicit stake in the ‘vernacular’ language of the researched, in the ‘scientific’ language of the researcher and in the relationship of continuity between the two. Drawing on literature within gay and lesbian/queer studies and cross-cultural studies, this chapter revisits debates on sexuality, language and intersectionality. I argue for the importance of giving careful consideration to the language we choose to use as researchers to collectively define the people whose experiences we try to capture. I also propose that language itself can be investigated as a productive way to foreground how individual and collective identifications are discursively constructed, and to unpack the diversity of lived experience. I address intersectional complexity as a methodological issue, where methodology is understood not only as the methods and practicalities of doing research, but more broadly as ‘a coherent set of ideas about the philosophy, methods and data that underlie the research process and the production of knowledge’ (McCall 2005:1774). My points are illustrated with examples drawn from my ethnographic study on ‘lesbian’ identity in urban Russia, interspersed with insights from existing literature. In particular, I aim to show that an explicit focus on language can be a productive way to explore the intersections between the global, the national and the local in cross-cultural research on sexuality, while also addressing issues of positionality and accountability to the communities researched
S-duality as a beta-deformed Fourier transform
An attempt is made to formulate Gaiotto's S-duality relations in an explicit
quantitative form. Formally the problem is that of evaluation of the Racah
coefficients for the Virasoro algebra, and we approach it with the help of the
matrix model representation of the AGT-related conformal blocks and Nekrasov
functions. In the Seiberg-Witten limit, this S-duality reduces to the Legendre
transformation. In the simplest case, its lifting to the level of Nekrasov
functions is just the Fourier transform, while corrections are related to the
beta-deformation. We calculate them with the help of the matrix model approach
and observe that they vanish for beta=1. Explicit evaluation of the same
corrections from the U_q(sl(2)) infinite-dimensional representation formulas
due to B.Ponsot and J.Teshner remains an open problem.Comment: 21 page
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