16,220 research outputs found
Measurements incompatible in Quantum Theory cannot be measured jointly in any other local theory
It is well known that jointly measurable observables cannot lead to a
violation of any Bell inequality - independent of the state and the
measurements chosen at the other site. In this letter we prove the converse:
every pair of incompatible quantum observables enables the violation of a Bell
inequality and therefore must remain incompatible within any other no-signaling
theory. While in the case of von Neumann measurements it is sufficient to use
the same pair of observables at both sites, general measurements can require
different choices. The main result is obtained by showing that for arbitrary
dimension the CHSH inequality provides the Lagrangian dual of the
characterization of joint measurability. This leads to a simple criterion for
joint measurability beyond the known qubit case.Comment: 4 page
Quantum phase transitions of atom-molecule Bose mixtures in a double-well potential
The ground state and spectral properties of Bose gases in double-well
potentials are studied in two different scenarios: i) an interacting atomic
Bose gas, and ii) a mixture of an atomic gas interacting with diatomic
molecules. A ground state second-order quantum phase transition (QPT) is
observed in both scenarios. For large attractive values of the atom-atom
interaction, the ground-state is degenerate. For repulsive and small attractive
interaction, the ground-state is not degenerate and is well approximated by a
boson coherent state. Both systems depict an excited state quantum phase
transition (ESQPT). For the mixed atom-molecule system the critical point of
the ESQPT displays a discontinuity in the first derivative of the density of
states.Comment: 25 pages, 18 figures. RevTex 4.1 (version to appear in Phys. Rev. E
Excited-state quantum phase transitions in a two-fluid Lipkin model
Background: Composed systems have became of great interest in the framework
of the ground state quantum phase transitions (QPTs) and many of their
properties have been studied in detail. However, in these systems the study of
the so called excited-state quantum phase transitions (ESQPTs) have not
received so much attention.
Purpose: A quantum analysis of the ESQPTs in the two-fluid Lipkin model is
presented in this work. The study is performed through the Hamiltonian
diagonalization for selected values of the control parameters in order to cover
the most interesting regions of the system phase diagram. [Method:] A
Hamiltonian that resembles the consistent-Q Hamiltonian of the interacting
boson model (IBM) is diagonalized for selected values of the parameters and
properties such as the density of states, the Peres lattices, the
nearest-neighbor spacing distribution, and the participation ratio are
analyzed.
Results: An overview of the spectrum of the two-fluid Lipkin model for
selected positions in the phase diagram has been obtained. The location of the
excited-state quantum phase transition can be easily singled out with the Peres
lattice, with the nearest-neighbor spacing distribution, with Poincar\'e
sections or with the participation ratio.
Conclusions: This study completes the analysis of QPTs for the two-fluid
Lipkin model, extending the previous study to excited states. The ESQPT
signatures in composed systems behave in the same way as in single ones,
although the evidences of their presence can be sometimes blurred. The Peres
lattice turns out to be a convenient tool to look into the position of the
ESQPT and to define the concept of phase in the excited states realm
Impact of the Intensive Program of Emotional Intelligence (IPEI) on middle man-agers’ emotional intelligence
Background: This study aimed to evaluate the effect of the Intensive Program of Emo-tional Intelligence (IPEI; Fernández, 2015) on middle managers’ emotional intelligence, as this variable may have a significant impact on personal satisfaction, task performance, and work environment. Method: The intervention was applied on work team supervisors from a big call center, as it is an overlooked sector in this topic. Two-hundred and eighty-two supervisors from a Spanish multinational Madrid-based company (51.4% males and 48.6% females) participated in this study. Participants were assigned to the experimental group (n = 190) or the control group (n = 92) by availability, according to management decision. All supervisors filled in two questionnaires to evaluate the differ-ent components of intrapersonal emotional intelligence (i.e., attention, clarity, and repair; TMMS-24; Fernández-Berrocal, Extremera, & Ramos, 2004) and cognitive and affec-tive empathy (i.e., perspective taking, emotion understanding, empathic joy, and person-al distress; TECA; López-Pérez, Fernández, & Abad, 2008). Results: The findings showed an increase in the studied variables for the experimental group. Conclusions: The obtained results support middle managers’ training on emotional competences through short, efficient, and economic programs, and it was discussed potential limita-tions and implications of the obtained results
Editorial: Gaze and postural stability rehabilitation
Proprioceptive, Visual, Vestibular, and Cognitive systems interact in a continuous sensorial re-weighting, ensuring gaze and postural control (1, 2). The central nervous system integrates the information originating from these systems into a continuous sensorial re-weighting that ensures postural control in both static and dynamic conditions (3, 4). The contribution of each sensory system changes depending on environmental conditions and the motor task performed by the person (5–7). To tailor a rehabilitative program for patients with gaze and postural stability disorders, a multidimensional assessment is required. A wide range of both clinical and instrumental evaluations could be performed before the rehabilitative approach in order to obtain quantitative and qualitative information about the patient's balance and gait disorders, supporting the rehabilitative staff in designing the most suitable therapeutic intervention. Instrumental assessment of the vestibular system has made significant progress in recent years. Two protocol tests are available in the clinical practice to evaluate the Vestibular Ocular Reflex (VOR) function through the use of Video Head Impulse Test (vHIT): Head Impulse Paradigm (HIMP) and Suppression Head Impulse Paradigm (SHIMP) (8–10). The head turn stimulus and the eye movement recording are identical. All that is changed are the instructions—from “look at that fixed target on the wall” to “look at the moving target.” At the same time, vestibular-evoked myogenic potentials are the most suitable test to evaluate otolith functions in patients with unilateral vestibular hypofunction in the acute and sub-acute phase
Helping patients discuss CINV management : development of a patient charter
In April 2012, an Expert Group of specialist cancer nurses working in a variety of settings (e.g. chemotherapy delivery, chemotherapy service design, research, nurse leadership and patient information/advocacy) participated in telephone/web-based meetings, with the aim of sharing current experience of chemotherapy-induced nausea and vomiting (CINV) management, and reaching a consensus on the development of a Patient Charter, designed to help patients understand CINV management, and setting out key questions they may wish to ask their healthcare professionals
Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution
The chemical composition of the gas in galaxies versus cosmic time provides a
very important tool for understanding galaxy evolution. Although there are many
studies at high redshift, they are rather scarce at lower redshifts. However,
low redshift studies can provide important clues about the evolution of
galaxies, furnishing the required link between local and high redshift
universe. In this work we focus on the metallicity of the gas of star-forming
galaxies at low redshift, looking for signs of chemical evolution.
To analyze the metallicity contents star-forming galaxies of similar
luminosities and masses at different redshifts. With this purpose, we present a
study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star
forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5),
using different redshift intervals from 0.04 to 0.4.
We used data processed with the STARLIGHT spectral synthesis code, correcting
the fluxes for dust extinction, estimating metallicities using the R_23 method,
and segregating the samples with respect to the value of the
[NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting
the upper branch. We analyze the luminosity and mass-metallicity relations, and
the effect of the Sloan fiber diameter looking for possible biases.
By dividing our redshift samples in intervals of similar magnitude and
comparing them, significant signs of metallicity evolution are found.
Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a
decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&
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Is idiosyncratic volatility priced in commodity futures markets?
This article investigates the relationship between expected returns and past idiosyncratic volatility in commodity futures markets. Measuring the idiosyncratic volatility of 27 commodity futures contracts with traditional pricing models that fail to account for backwardation and contango leads to the puzzling finding that idiosyncratic volatility is significantly negatively priced cross-sectionally. However, idiosyncratic volatility is not priced when the phases of backwardation and contango are suitably factored in the pricing model. A time-series portfolio analysis similarly suggests that failing to recognize the fundamental risk associated with the inexorable phases of backwardation and contango leads to overstated profitability of the idiosyncratic volatility mimicking portfolios
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