3,256 research outputs found
Enhancing Tc in field-doped Fullerenes by applying uniaxial stress
Capitalizing on the two-dimensional nature of superconductivity in
field-effect doped C60, we show that it should be possible to increase the
transition temperature Tc by applying uniaxial stress perpendicular to the gate
electrode. This method not only holds the promise of substantially enhancing Tc
(by about 30 K per GPa), but also provides a sensitive check of the current
understanding of superconductivity in the doped Fullerenes.Comment: 3 pages RevTe
Sequential generation of entangled multi-qubit states
We consider the deterministic generation of entangled multi-qubit states by
the sequential coupling of an ancillary system to initially uncorrelated
qubits. We characterize all achievable states in terms of classes of matrix
product states and give a recipe for the generation on demand of any
multi-qubit state. The proposed methods are suitable for any sequential
generation-scheme, though we focus on streams of single photon time-bin qubits
emitted by an atom coupled to an optical cavity. We show, in particular, how to
generate familiar quantum information states such as W, GHZ, and cluster
states, within such a framework.Comment: 4 pages and 2 figures, submitted for publicatio
Identifying Agile Requirements Engineering Patterns in Industry
Agile Software Development (ASD) is gaining in popularity in today´s business world. Industry is adopting agile methodologies both to accelerate value delivery and to enhance the ability to deal with changing requirements. However, ASD has a great impact on how Requirements Engineering (RE) is carried out in agile environments. The integration of Human-Centered Design (HCD) plays an important role due to the focus on user and stakeholder involvement. To this end, we aim to introduce agile RE patterns as main objective of this paper. On the one hand, we will describe our pattern mining process based on empirical research in literature and industry. On the other hand, we will discuss our results and provide two examples of agile RE patterns. In sum, the pattern mining process identifies 41 agile RE patterns. The accumulated knowledge will be shared by means of a web application.Ministerio de EconomĂa y Competitividad TIN2013-46928-C3-3-RMinisterio de EconomĂa y Competitividad TIN2016-76956-C3-2-RMinisterio de EconomĂa y Competitividad TIN2015-71938-RED
The possible explanation of electric-field-doped C60 phenomenology in the framework of Eliashberg theory
In a recent paper (J.H. Schon, Ch. Kloc, R.C. Haddon and B. Batlogg, Nature
408 (2000) 549) a large increase in the superconducting critical temperature
was observed in C60 doped with holes by application of a high electric field.
We demonstrate that the measured Tc versus doping curves can be explained by
solving the (four) s-wave Eliashberg equations in the case of a finite,
non-half-filled energy band. In order to reproduce the experimental data, we
assume a Coulomb pseudopotential depending on the filling in a very simple and
plausible way. Reasonable values of the physical parameters involved are
obtained. The application of the same approach to new experimental data (J.H.
Schon, Ch. Kloc and B. Batlogg, Science 293 (2001) 2432) on electric
field-doped, lattice-expanded C60 single crystals (Tc=117 K in the hole-doped
case) gives equally good results and sets a theoretical limit to the linear
increase of Tc at the increase of the lattice spacing.Comment: latex2e, 6 pages, 7 figures, 1 table, revised versio
Sequential Generation of Matrix-Product States in Cavity QED
We study the sequential generation of entangled photonic and atomic
multi-qubit states in the realm of cavity QED. We extend the work of C. Schoen
et al. [Phys. Rev. Lett. 95, 110503 (2005)], where it was shown that all states
generated in a sequential manner can be classified efficiently in terms of
matrix-product states. In particular, we consider two scenarios: photonic
multi-qubit states sequentially generated at the cavity output of a
single-photon source and atomic multi-qubit states generated by their
sequential interaction with the same cavity mode.Comment: 11 page
A new physarum learner for network structure learning from biomedical data
A novel structure learning algorithm for Bayesian Networks based on a Physarum Learner is presented. The
length of the connections within an initially fully connected Physarum-Maze is taken as the inverse Pearson
correlation coefficient between the connected nodes. The Physarum Learner then estimates the shortest indirect
paths between each pair of nodes. In each iteration, a score of the surviving edges is incremented.
Finally, the highest scored connections are combined to form a Bayesian Network. The novel Physarum
Learner method is evaluated with different configurations and compared to the LAGD Hill Climber showing
comparable performance with respect to quality of training results and increased time efficiency for large data
sets
The role of law and ethics in developing business management as a profession
Currently, business management is far from being recognised as a profession. This paper suggests that a professional spirit should be developed which could function as a filter of commercial reasoning. Broadly, management will not be organised within the framework of a well-established profession unless formal knowledge, licensing, professional autonomy and professional codes of conduct are developed sufficiently. In developing business management as a profession, law may play a key role. Where the idea is that business management should be more professsionalised, managers must show that they are willing to adopt ethical values, while arriving at business decisions. The paper argues that ethics cannot survive without legal regulation, which, in turn, will not be supported by law unless lawyers can find alternative solutions to the large mechanisms of the official society, secured by the monopolised coercion of the nation state. From a micro perspective of law and business ethics, communities can be developed with their own conventions, rules and standards that are generated and sanctioned within the boundaries of the communities themselves
How to get from imaginary to real chemical potential
Using the exactly solvable Gross-Neveu model as theoretical laboratory, we
analyse in detail the relationship between a relativistic quantum field theory
at real and imaginary chemical potential. We find that one can retrieve the
full information about the phase diagram of the theory from an imaginary
chemical potential calculation. The prerequisite is to evaluate and
analytically continue the effective potential for the chiral order parameter,
rather than thermodynamic observables or phase boundaries. In the case of an
inhomogeneous phase, one needs to compute the full effective action, a
functional of the space-dependent order parameter, at imaginary chemical
potential.Comment: revtex, 9 pages, 10 figures; v2: add more references, modify
concluding sectio
Spin-orbit interaction and spin relaxation in a two-dimensional electron gas
Using time-resolved Faraday rotation, the drift-induced spin-orbit Field of a
two-dimensional electron gas in an InGaAs quantum well is measured. Including
measurements of the electron mobility, the Dresselhaus and Rashba coefficients
are determined as a function of temperature between 10 and 80 K. By comparing
the relative size of these terms with a measured in-plane anisotropy of the
spin dephasing rate, the D'yakonv-Perel' contribution to spin dephasing is
estimated. The measured dephasing rate is significantly larger than this, which
can only partially be explained by an inhomogeneous g-factor.Comment: 6 pages, 5 figure
Mycobacterium tuberculosis drug-resistance testing: challenges, recent developments and perspectives
Drug-resistance testing, or antimicrobial susceptibility testing (AST), is mandatory for Mycobacterium tuberculosis in cases of failure on standard therapy. We reviewed the different methods and techniques of phenotypic and genotypic approaches. Although multiresistant and extensively drug-resistant (MDR/XDR) tuberculosis is present worldwide, AST for M. tuberculosis (AST-MTB) is still mainly performed according to the resources available rather than the drug-resistance rates. Phenotypic methods, i.e. culture-based AST, are commonly used in high-income countries to confirm susceptibility of new cases of tuberculosis. They are also used to detect resistance in tuberculosis cases with risk factors, in combination with genotypic tests. In low-income countries, genotypic methods screening hot-spot mutations known to confer resistance were found to be easier to perform because they avoid the culture and biosafety constraint. Given that genotypic tests can rapidly detect the prominent mechanisms of resistance, such as the rpoB mutation for rifampicin resistance, we are facing new challenges with the observation of false-resistance (mutations not conferring resistance) and false-susceptibility (mutations different from the common mechanism) results. Phenotypic and genotypic approaches are therefore complementary for obtaining a high sensitivity and specificity for detecting drug resistances and susceptibilities to accurately predict MDR/XDR cure and to gather relevant data for resistance surveillance. Although AST-MTB was established in the 1960s, there is no consensus reference method for MIC determination against which the numerous AST-MTB techniques can be compared. This information is necessary for assessing in vitro activity and setting breakpoints for future anti-tuberculosis agents
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