5,556 research outputs found
Propagation and spectral properties of quantum walks in electric fields
We study one-dimensional quantum walks in a homogeneous electric field. The
field is given by a phase which depends linearly on position and is applied
after each step. The long time propagation properties of this system, such as
revivals, ballistic expansion and Anderson localization, depend very
sensitively on the value of the electric field , e.g., on whether
is rational or irrational. We relate these properties to the
continued fraction expansion of the field. When the field is given only with
finite accuracy, the beginning of the expansion allows analogous conclusions
about the behavior on finite time scales.Comment: 7 pages, 4 figure
Fidelity and Concurrence of conjugated states
We prove some new properties of fidelity (transition probability) and
concurrence, the latter defined by straightforward extension of Wootters
notation. Choose a conjugation and consider the dependence of fidelity or of
concurrence on conjugated pairs of density operators. These functions turn out
to be concave or convex roofs. Optimal decompositions are constructed. Some
applications to two- and tripartite systems illustrate the general theorem.Comment: 10 pages, RevTex, Correction: Enlarged, reorganized version. More
explanation
A simple abstraction of arrays and maps by program translation
We present an approach for the static analysis of programs handling arrays,
with a Galois connection between the semantics of the array program and
semantics of purely scalar operations. The simplest way to implement it is by
automatic, syntactic transformation of the array program into a scalar program
followed analysis of the scalar program with any static analysis technique
(abstract interpretation, acceleration, predicate abstraction,.. .). The
scalars invariants thus obtained are translated back onto the original program
as universally quantified array invariants. We illustrate our approach on a
variety of examples, leading to the " Dutch flag " algorithm
Self-reported knee symptoms assessed by KOOS questionnaire in downhill runners (skyrunners)
Background: The knee is the weight-bearing joint most commonly associated with sports injuries, and therefore is most at risk of developing degenerative changes, including osteoarthritis. Skyrunners can be considered to be at risk of developing symptoms of post-traumatic osteoarthritis due to downhill running. Aim: The aim of this study was to analyze the health of the knee joints of a large group of these athletes via a specific self-report questionnaire. Methods: This study was carried out by asking the participants of seven official Skyraces (22.4±3.1 km length; 1596±393 m elevation) to fill out a questionnaire. Information regarding age, sex, downhill elevation (m) during training and competitions over the last month, and history of previous knee injury was also collected before the participants filled out the Knee injury and Osteoarthritis Outcome Score (KOOS), which is a reliable and validated instrument designed to assess patients' opinions about their knees and associated problems that can result in post-traumatic osteoarthritis. Athletes were divided into six age groups (from 17 to 70 years) and 12 groups based on the downhill gradient they had covered over the last month (from 1,000 to 40,000 m). Results: Six hundred twenty-one questionnaires were collected from 45% of the participants in the seven races. Multivariate analysis revealed that self-reported KOOS scores were unrelated to age, sex and monthly downhill gradient. Only 74 (12%) of the participants reported previous knee injuries. Significant differences in the five subscales of the KOOS were found between skyrunners with and without previous knee injuries (P<0.01). Conclusions: In the studied population, regular training for downhill running and participation in Skyraces could not be considered risk factors for subjective knee symptoms. Skyrunners with selfreported histories of knee injuries scored worse on all five subscales of the KOO
Spectral Conditions on the State of a Composite Quantum System Implying its Separability
For any unitarily invariant convex function F on the states of a composite
quantum system which isolates the trace there is a critical constant C such
that F(w)<= C for a state w implies that w is not entangled; and for any
possible D > C there are entangled states v with F(v)=D. Upper- and lower
bounds on C are given. The critical values of some F's for qubit/qubit and
qubit/qutrit bipartite systems are computed. Simple conditions on the spectrum
of a state guaranteeing separability are obtained. It is shown that the thermal
equilbrium states specified by any Hamiltonian of an arbitrary compositum are
separable if the temperature is high enough.Comment: Corrects 1. of Lemma 2, and the (under)statement of Proposition 7 of
the earlier version
Simple solid-phase spectrophotometric method for free iron(III) determination
A simple and rapid solid-phase spectrophotometric procedure to determine free Fe(III) in environmental and biological samples is proposed. In particular, a deferoxamine (DFO) self assembled monolayer on mesoporous silica (DFO SAMMS) is developed and here applied as a sensor for iron(III). The solid product became brownish when put in contact with iron(III) solutions; so an immediate application as colorimetric sensor is considered. In order to optimize the DFO SAMMS synthesis and to obtain the best product for iron(III) sensing, a factorial experimental design is performed selecting the maximum absorption at 425 nm as response. The robustness of the spectrophotometric method is also proved
Structured Deformations of Continua: Theory and Applications
The scope of this contribution is to present an overview of the theory of
structured deformations of continua, together with some applications.
Structured deformations aim at being a unified theory in which elastic and
plastic behaviours, as well as fractures and defects can be described in a
single setting. Since its introduction in the scientific community of rational
mechanicists (Del Piero-Owen, ARMA 1993), the theory has been put in the
framework of variational calculus (Choksi-Fonseca, ARMA 1997), thus allowing
for solution of problems via energy minimization. Some background, three
problems and a discussion on future directions are presented.Comment: 11 pages, 1 figure, 1 diagram. Submitted to the Proceedings volume of
the conference CoMFoS1
Regulation of Marginal Zone B-Cell Differentiation by MicroRNA-146a.
B-cell development in the bone marrow is followed by specification into functional subsets in the spleen, including marginal zone (MZ) B-cells. MZ B-cells are classically characterized by T-independent antigenic responses and require the elaboration of distinct gene expression programs for development. Given their role in gene regulation, it is not surprising that microRNAs are important factors in B-cell development. Recent work demonstrated that deficiency of the NFκB feedback regulator, miR-146a, led to a range of hematopoietic phenotypes, but B-cell phenotypes have not been extensively characterized. Here, we found that miR-146a-deficient mice demonstrate a reduction in MZ B-cells, likely from a developmental block. Utilizing high-throughput sequencing and comparative analysis of developmental stage-specific transcriptomes, we determined that MZ cell differentiation was impaired due to decreases in Notch2 signaling. Our studies reveal miR-146a-dependent B-cell phenotypes and highlight the complex role of miR-146a in the hematopoietic system
Quantum Games
In these lecture notes we investigate the implications of the identification
of strategies with quantum operations in game theory beyond the results
presented in [J. Eisert, M. Wilkens, and M. Lewenstein, Phys. Rev. Lett. 83,
3077 (1999)]. After introducing a general framework, we study quantum games
with a classical analogue in order to flesh out the peculiarities of game
theoretical settings in the quantum domain. Special emphasis is given to a
detailed investigation of different sets of quantum strategies.Comment: 13 pages (LaTeX), 3 figure
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