12,015 research outputs found

    Entropic Inequalities for a Class of Quantum Secret Sharing States

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    It is well-known that von Neumann entropy is nonmonotonic unlike Shannon entropy (which is monotonically nondecreasing). Consequently, it is difficult to relate the entropies of the subsystems of a given quantum state. In this paper, we show that if we consider quantum secret sharing states arising from a class of monotone span programs, then we can partially recover the monotonicity of entropy for the so-called unauthorized sets. Furthermore, we can show for these quantum states the entropy of the authorized sets is monotonically nonincreasing.Comment: LaTex, 5 page

    No-Cloning Theorem on Quantum Logics

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    This paper discusses the no-cloning theorem in a logico-algebraic approach. In this approach, an orthoalgebra is considered as a general structure for propositions in a physical theory. We proved that an orthoalgebra admits cloning operation if and only if it is a Boolean algebra. That is, only classical theory admits the cloning of states. If unsharp propositions are to be included in the theory, then a notion of effect algebra is considered. We proved that an atomic Archimedean effect algebra admitting cloning operation is a Boolean algebra. This paper also presents a partial result indicating a relation between cloning on effect algebras and hidden variables.Comment: To appear in J. Math. Phy

    77Se NMR Investigation of the K(x)Fe(2-y)Se(2) High Tc Superconductor (Tc=33K)

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    We report a comprehensive 77Se NMR study of the structural, magnetic, and superconducting properties of a single crystalline sample of the newly discovered FeSe-based high temperature superconductor K(x)Fe(2-y)Se(2) (Tc=33K) in a broad temperature range up to 290 K. We will compare our results with those reported for FeSe (Tc=9K) and FeAs-based high Tc systems.Comment: Final versio

    The complement binding-like domains of the murine homing receptor facilitate lectin activity.

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    The leukocyte homing receptor (HR), the endothelial leukocyte adhesion molecule, and gmp140/platelet activation-dependent granule membrane protein are members of a family of adhesion molecules, termed the lectin cell adhesion molecules (LEC-CAMS) which are unified by a multi-domain structure containing a lectin motif, an epidermal growth factor-like (egf) motif, and variable numbers of a complement binding-like (CB) motif. Previous data have indicated a predominant role for the lectin motif in cell adhesion directed by the LEC-CAMS, although the egf-like domain of the HR may also play a potential role in cell binding. While the role(s) of the CB domains in the LEC-CAMS is currently not understood, they have been hypothesized to act as rigid spacers or stalks for lectin and perhaps, egf domain presentation. In this paper, we analyze the functional characteristics of murine HR-IgG chimeras containing the lectin, lectin plus egf, and lectin plus egf plus CB domains. The Mel 14 mAb, an adhesion blocking antibody which recognizes a conformational determinant in the N-terminus of the HR lectin domain, shows a significantly decreased affinity for a HR construct which lacks the CB motifs, consistent with the possibility that the CB domains are involved with lectin domain structure. In agreement with this conjecture, HR mutants lacking the CB domains show a profound decrease in lectin-specific interaction with the carbohydrate polyphosphomannan ester, suggesting that the changes in Mel 14 affinity for the lectin domain are reflected in lectin functionality. Various assays investigating the interactions between the HR deletion mutants and the peripheral lymph node high endothelium, including cell blocking, immunohistochemical staining, and radioactively labeled ligand binding, all showed that removal of the CB domains results in a lack of HR adhesive function. These results imply that the CB domains of the HR, and, by analogy, the other members of the LEC-CAM family, may play important structural roles involving induction of lectin domain conformation and resultant functionality

    NMR Characterization of Sulphur Substitution Effects in the K(x)Fe(2-y)Se(2-z)S(z) high Tc Superconductor

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    We present an NMR study of the effect of S substitution in the high Tc superconductor K(x)Fe(2-y)Se(2-z)S(z) in a temperature range up to 250 K. We present NMR Knight shift and nuclear spin-lattice relaxation rate 1/T1 data, and compare our results to that of the non-substituted system K(x)Fe(2-y)Se(2).Comment: Typos fixed, figure replace

    Multilevel Coded Modulation for Unequal Error Protection and Multistage Decoding—Part I: Symmetric Constellations

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    In this paper, theoretical upper bounds and computer simulation results on the error performance of multilevel block coded modulations for unequal error protection (UEP) and multistage decoding are presented. It is shown that nonstandard signal set partitionings and multistage decoding provide excellent UEP capabilities beyond those achievable with conventional coded modulation. The coding scheme is designed in such a way that the most important information bits have a lower error rate than other information bits. The large effective error coefficients, normally associated with standard mapping by set partitioning, are reduced by considering nonstandard partitionings of the underlying signal set. The bits-to-signal mappings induced by these partitionings allow the use of soft-decision decoding of binary block codes. Moreover, parallel operation of some of the staged decoders is possible, to achieve high data rate transmission, so that there is no error propagation between these decoders. Hybrid partitionings are also considered that trade off increased intraset distances in the last partition levels with larger effective error coefficients in the middle partition levels. The error performance of specific examples of multilevel codes over 8-PSK and 64-QAM signal sets are simulated and compared with theoretical upper bounds on the error performance

    Shrinkage Estimators in Online Experiments

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    We develop and analyze empirical Bayes Stein-type estimators for use in the estimation of causal effects in large-scale online experiments. While online experiments are generally thought to be distinguished by their large sample size, we focus on the multiplicity of treatment groups. The typical analysis practice is to use simple differences-in-means (perhaps with covariate adjustment) as if all treatment arms were independent. In this work we develop consistent, small bias, shrinkage estimators for this setting. In addition to achieving lower mean squared error these estimators retain important frequentist properties such as coverage under most reasonable scenarios. Modern sequential methods of experimentation and optimization such as multi-armed bandit optimization (where treatment allocations adapt over time to prior responses) benefit from the use of our shrinkage estimators. Exploration under empirical Bayes focuses more efficiently on near-optimal arms, improving the resulting decisions made under uncertainty. We demonstrate these properties by examining seventeen large-scale experiments conducted on Facebook from April to June 2017
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