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A pilot study of a text messaging intervention to modify illness and medication beliefs amongst patients diagnosed with inflammatory bowel disease
Intentional and unintentional medication non-adherence is a particular challenge for patients with inflammatory bowel disease (IBD). Non-adherence can affect patientsâ quality of life, which can result in unfavorable treatment outcomes, more hospitalizations, and higher healthcare-related costs. The purpose of this study was to assess whether a tailored text message intervention designed to modify illness and medication adherence beliefs in patients with IBD would increase treatment compliance and change patientsâ illness perceptions and medication concerns. This pilot study utilized a pre-test-post-test non-randomized design. A sample of 32 IBD patients was recruited within the UK. Participantsâ medication beliefs and illness perception scores determined the set of tailored daily text messages, which were sent to patients over duration of 12 weeks. Medication adherence increased post-intervention, as âforgetting to take medicationâ decreased while âneverâ forgetting to take medication increased over time. A significant increase in treatment control and coherence and a decreased level of concern surrounding their condition was evident. Participantsâ level of concern towards their medications changed during the 12 weeks, with a baseline mean concern score of 3.08 (.57) in comparison to the 12 weeks mean concern score of 2.89 (.59), which is statistically different, t (31)â=â2.16, pâ<â.038, râ=â.36 (medium effect). Sixty-six percent of participants from the baseline were aware of the necessity of their medication: âwithout my medication I would become ill.â The results have direct implications for improving medication adherence and changing illness and medication beliefs. This study validated the benefits of text messages and highlighted the importance of addressing these beliefs in order to understand the reasons for non-adherence fully
Entanglement distribution by an arbitrarily inept delivery service
We consider the scenario where a company C manufactures in bulk pure
entangled pairs of particles, each pair intended for a distinct pair of distant
customers. Unfortunately, its delivery service is inept - the probability that
any given customer pair receives its intended particles is S, and the customers
cannot detect whether an error has occurred. Remarkably, no matter how small S
is, it is still possible for C to distribute entanglement by starting with
non-maximally entangled pairs. We determine the maximum entanglement
distributable for a given S, and also determine the ability of the parties to
perform nonlocal tasks with the qubits they receive.Comment: 5 pages, 3 figures. v2 includes minor change
Sharing Polarization within Quantum Subspaces
Given an ensemble of n spins, at least some of which are partially polarized,
we investigate the sharing of this polarization within a subspace of k spins.
We assume that the sharing results in a pseudopure state, characterized by a
single purity parameter which we call the bias. As a concrete example we
consider ensembles of spin-1/2 nuclei in liquid-state nuclear magnetic
resonance (NMR) systems. The shared bias levels are compared with some current
entanglement bounds to determine whether the reduced subspaces can give rise to
entangled states.Comment: 7 pages, 3 figure
Global Optical Control of a Quantum Spin Chain
Quantum processors which combine the long decoherence times of spin qubits
together with fast optical manipulation of excitons have recently been the
subject of several proposals. I show here that arbitrary single- and entangling
two-qubit gates can be performed in a chain of perpetually coupled spin qubits
solely by using laser pulses to excite higher lying states. It is also
demonstrated that universal quantum computing is possible even if these pulses
are applied {\it globally} to a chain; by employing a repeating pattern of four
distinct qubit units the need for individual qubit addressing is removed. Some
current experimental qubit systems would lend themselves to implementing this
idea.Comment: 5 pages, 3 figure
Geometric Aspects of Composite Pulses
Unitary operations acting on a quantum system must be robust against
systematic errors in control parameters for reliable quantum computing.
Composite pulse technique in nuclear magnetic resonance (NMR) realises such a
robust operation by employing a sequence of possibly poor quality pulses. In
this article, we demonstrate that two kinds of composite pulses, one
compensates for a pulse length error in a one-qubit system and the other
compensates for a J-coupling error in a twoqubit system, have vanishing
dynamical phase and thereby can be seen as geometric quantum gates, which
implement unitary gates by the holonomy associated with dynamics of cyclic
vectors defined in the text.Comment: 20 pages, 4 figures. Accepted for publication in Philosophical
Transactions of the Royal Society
Adjoint-Based Design of Rotors using the Navier-Stokes Equations in a Noninertial Reference Frame
Optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated using comparisons with a complex-variable technique, and a number of single- and multi-point optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined
Polarization Requirements for Ensemble Implementations of Quantum Algorithms with a Single Bit Output
We compare the failure probabilities of ensemble implementations of quantum
algorithms which use pseudo-pure initial states, quantified by their
polarization, to those of competing classical probabilistic algorithms.
Specifically we consider a class algorithms which require only one bit to
output the solution to problems. For large ensemble sizes, we present a general
scheme to determine a critical polarization beneath which the quantum algorithm
fails with greater probability than its classical competitor. We apply this to
the Deutsch-Jozsa algorithm and show that the critical polarization is 86.6%.Comment: 11 pages, 3 figure
Universal quantum computation by holonomic and nonlocal gates with imperfections
We present a nonlocal construction of universal gates by means of holonomic
(geometric) quantum teleportation. The effect of the errors from imperfect
control of the classical parameters, the looping variation of which builds up
holonomic gates, is investigated. Additionally, the influence of quantum
decoherence on holonomic teleportation used as a computational primitive is
studied. Advantages of the holonomic implementation with respect to control
errors and dissipation are presented.Comment: 5 pages, 2 figures, REVTEX, title changed, typos correcte
Entanglement and Symmetry: A Case Study in Superselection Rules, Reference Frames, and Beyond
This paper concentrates on a particular example of a constraint imposed by
superselection rules (SSRs): that which applies when the parties (Alice and
Bob) cannot distinguish among certain quantum objects they have. This arises
naturally in the context of ensemble quantum information processing such as in
liquid NMR. We discuss how a SSR for the symmetric group can be applied, and
show how the extractable entanglement can be calculated analytically in certain
cases, with a maximum bipartite entanglement in an ensemble of N Bell-state
pairs scaling as log(N) as N goes to infinity . We discuss the apparent
disparity with the asymptotic (N >> 1) recovery of unconstrained entanglement
for other sorts of superselection rules, and show that the disparity disappears
when the correct notion of applying the symmetric group SSR to multiple copies
is used. Next we discuss reference frames in the context of this SSR, showing
the relation to the work of von Korff and Kempe [Phys. Rev. Lett. 93, 260502
(2004)]. The action of a reference frame can be regarded as the analog of
activation in mixed-state entanglement. We also discuss the analog of
distillation: there exist states such that one copy can act as an imperfect
reference frame for another copy. Finally we present an example of a stronger
operational constraint, that operations must be non-collective as well as
symmetric. Even under this stronger constraint we nevertheless show that
Bell-nonlocality (and hence entanglement) can be demonstrated for an ensemble
of N Bell-state pairs no matter how large N is. This last work is a
generalization of that of Mermin [Phys. Rev. D 22, 356 (1980)].Comment: 16 pages, 6 figures. v2 updated version published in Phys Rev
Quantum Entanglement in the Two Impurity Kondo Model
In order to quantify quantum entanglement in two impurity Kondo systems, we
calculate the concurrence, negativity, and von Neumann entropy. The
entanglement of the two Kondo impurities is shown to be determined by two
competing many-body effects, the Kondo effect and the
Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, . Due to the
spin-rotational invariance of the ground state, the concurrence and negativity
are uniquely determined by the spin-spin correlation between the impurities. It
is found that there exists a critical minimum value of the antiferromagnetic
correlation between the impurity spins which is necessary for entanglement of
the two impurity spins. The critical value is discussed in relation with the
unstable fixed point in the two impurity Kondo problem. Specifically, at the
fixed point there is no entanglement between the impurity spins. Entanglement
will only be created (and quantum information processing (QIP) be possible) if
the RKKY interaction exchange energy, , is at least several times larger
than the Kondo temperature, . Quantitative criteria for QIP are given in
terms of the impurity spin-spin correlation.Comment: 7 pages, 3 figures, 1 tabl
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