410 research outputs found

    Operator *-correspondences in analysis and geometry

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    An operator *-algebra is a non-selfadjoint operator algebra with completely isometric involution. We show that any operator *-algebra admits a faithful representation on a Hilbert space in such a way that the involution coincides with the operator adjoint up to conjugation by a symmetry. We introduce operator *-correspondences as a general class of inner product modules over operator *-algebras and prove a similar representation theorem for them. From this we derive the existence of linking operator *-algebras for operator *-correspondences. We illustrate the relevance of this class of inner product modules by providing numerous examples arising from noncommutative geometry.Comment: 31 pages. This work originated from the MFO workshop "Operator spaces and noncommutative geometry in interaction

    On the Grothendieck Theorem for jointly completely bounded bilinear forms

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    We show how the proof of the Grothendieck Theorem for jointly completely bounded bilinear forms on C*-algebras by Haagerup and Musat can be modified in such a way that the method of proof is essentially C*-algebraic. To this purpose, we use Cuntz algebras rather than type III factors. Furthermore, we show that the best constant in Blecher's inequality is strictly greater than one.Comment: 9 pages, minor change

    Total phallic construction techniques in transgender men: An updated narrative review

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    From 2012, the World Professional Association Transgender Health defined a structured therapeutic path and standards of care for transgender patients undergoing genital gender affirming surgery (GGAS). The main goal of GGAS in transgender males is to provide patients with an aesthetically appealing appearance of the neophallus that should allow standing micturition and enabling penetrative intercourse along with erogenous and tactile sensitivity. The optimal procedure should be safe, reproducible and performed in the fewest number of surgical stages. The ideal technique for total phallic construction (TPC) has not yet been demonstrated; TPC remains challenging and, from a functional point of view, it is also make more demanding as yet there are no perfect replacement materials for erectile and urethral tissues. Several procedures and different type of flaps (pedicled and free-flaps) have been proposed and investigated over time to address TPC with significant advances over the years especially after microsurgical procedures introduction. Due to its high complexity TPC is not free from complications. Local tissue ischaemic complications, complete and partial flap loss, donor site morbidity and urethral complications (fistulae and strictures) are reported. This narrative review aims to provide the readers with a contemporary overview of surgical procedures for TPC in transgender males focusing on key surgical steps, as well as surgical and functional outcomes

    Eradication of poliomyelitis in South Africa

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    An international campaign under the leadership of the World Health Organisation is underway to eradicate polio from the world by the year 2000. South Africa may already be free of polio. However, to ensure eradication we need to move from a polio control programme to a polio eradication programme. This necessitates the institution of a surveillance programme for acute flaccid paralysis (AFP) and improvement of the delivery of polio vaccine. All children with AFP (including those with suspected GuillainBarre syndrome) should be investigated with stool culture to exclude polio. Primary care services need strengthening so that oral polio vaccine coverage greater than 90% is achieved in all regions by all authorities. Outbreak response activities need to be developed. Consideration needs to be given to national immunisation days and mopping-up activities

    Noncommutative Figa-Talamanca-Herz algebras for Schur multipliers

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    We introduce a noncommutative analogue of the Fig\'a-Talamanca-Herz algebra Ap(G)A_p(G) on the natural predual of the operator space Mp,cb\frak{M}_{p,cb} of completely bounded Schur multipliers on Schatten space SpS_p. We determine the isometric Schur multipliers and prove that the space Mp\frak{M}_{p} of bounded Schur multipliers on Schatten space SpS_p is the closure in the weak operator topology of the span of isometric multipliers.Comment: 24 pages; corrected typo

    On peak phenomena for non-commutative HH^\infty

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    A non-commutative extension of Amar and Lederer's peak set result is given. As its simple applications it is shown that any non-commutative HH^\infty-algebra H(M,τ)H^\infty(M,\tau) has unique predual,and moreover some restriction in some of the results of Blecher and Labuschagne are removed, making them hold in full generality.Comment: final version (the presentation of some part is revised and one reference added

    Genetic engineering, production and characterisation of monomeric variants of the dimeric Serratia marcescens endonuclease

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    The Serratia nuclease is a non-specific endonuclease which cleaves single- and double-stranded RNA and DNA. It is a member of a large family of related endonucleases, most of which fire dimers of identical subunits, with the notable exception of the Anabaena nuclease which is a monomer. In order to find out whether the dimer state of the Serratia nuclease is essential for its function we have produced variants of this nuclease which based on the crystal structure (Miller, M.D. and Krause, K.L. (1996), Protein Science 5, 24-33) were expected to be unable to dimerise. We demonstrate here that these variants, H184A, H1184N, H184T and H184R, are monomers and have the same secondary structure, stability towards chemical denaturation and activity as the wild-type enzyme. This allows to conclude that the dimeric state is not essential for the catalytic function of the Serratia nuclease. In contrast, the S179C variant which is also a monomer shows little activity, presumably because this amino acid substitution changes the structure of the enzyme

    A new limit of T-violating transverse muon polarization in the K+π0μ+νK^{+}\to\pi^{0}\mu^{+} \nu decay

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    A search for T-violating transverse muon polarization (PTP_T) in the K+π0μ+νK^{+}\to \pi^{0}\mu^{+}\nu decay was performed using kaon decays at rest. A new improved value, PT=0.0017±0.0023(stat)±0.0011(syst)P_T= -0.0017\pm 0.0023 (stat)\pm 0.0011 (syst), was obtained giving an upper limit, PT<0.0050| P_T | < 0.0050. The T-violation parameter was determined to be Imξ=0.0053±0.0071(stat)±0.0036(syst)\xi = -0.0053 \pm 0.0071(stat)\pm 0.0036(syst) giving an upper limit, |Imξ<0.016\xi| <0.016.Comment: 5 pages, 4 figure

    Large violation of Bell inequalities with low entanglement

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    In this paper we obtain violations of general bipartite Bell inequalities of order nlogn\frac{\sqrt{n}}{\log n} with nn inputs, nn outputs and nn-dimensional Hilbert spaces. Moreover, we construct explicitly, up to a random choice of signs, all the elements involved in such violations: the coefficients of the Bell inequalities, POVMs measurements and quantum states. Analyzing this construction we find that, even though entanglement is necessary to obtain violation of Bell inequalities, the Entropy of entanglement of the underlying state is essentially irrelevant in obtaining large violation. We also indicate why the maximally entangled state is a rather poor candidate in producing large violations with arbitrary coefficients. However, we also show that for Bell inequalities with positive coefficients (in particular, games) the maximally entangled state achieves the largest violation up to a logarithmic factor.Comment: Reference [16] added. Some typos correcte
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