1,074 research outputs found
Unique positive solution for an alternative discrete Painlevé I equation
We show that the alternative discrete Painleve I equation has a unique solution which remains positive for all n >0. Furthermore, we identify this positive solution in terms of a special solution of the second Painleve equation involving the Airy function Ai(t). The special-function solutions of the second Painleve equation involving only the Airy function Ai(t) therefore have the property that they remain positive for all n>0 and all t>0, which is a new characterization of these special solutions of the second Painlevé equation and the alternative discrete Painlevé I equation
Neuromuscular electrical stimulation prevents muscle wasting in critically ill comatose patients
This is the author accepted manuscript. The final version is available from Portland Press via the DOI in this recordFully sedated patients, being treated in the intensive care unit (ICU), experience substantial skeletal muscle loss. Consequently, survival rate is reduced and full recovery after awakening is compromised. Neuromuscular electrical stimulation (NMES) represents an effective method to stimulate muscle protein synthesis and alleviate muscle disuse atrophy in healthy subjects. We investigated the efficacy of twice-daily NMES to alleviate muscle loss in six fully sedated ICU patients admitted for acute critical illness [n=3 males, n=3 females; age 63 ± 6 y; APACHE II (Acute Physiology and Chronic Health Evaluation II) disease-severity-score: 29 ± 2]. One leg was subjected to twice-daily NMES of the quadriceps muscle for a period of 7 ± 1 day whereas the other leg acted as a non-stimulated control (CON). Directly before the first and on the morning after the final NMES session, quadriceps muscle biopsies were collected from both legs to assess muscle fibre-type-specific cross-sectional area (CSA). Furthermore, phosphorylation status of the key proteins involved in the regulation of muscle protein synthesis was assessed and mRNA expression of selected genes was measured. In the CON leg, type 1 and type 2 muscle-fibre-CSA decreased by 16 ± 9% and 24 ± 7% respectively (P<0.05). No muscle atrophy was observed in the stimulated leg. NMES increased mammalian target of rapamycin (mTOR) phosphorylation by 19 ± 5% when compared with baseline (P<0.05), with no changes in the CON leg. Furthermore, mRNA expression of key genes involved in muscle protein breakdown either declined [forkhead box protein O1 (FOXO1); P<0.05] or remained unchanged [muscle atrophy F-box (MAFBx) and muscle RING-finger protein-1 (MuRF1)], with no differences between the legs. In conclusion, NMES represents an effective and feasible interventional strategy to prevent skeletal muscle atrophy in critically ill comatose patients
Secure Coherent-state Quantum Key Distribution Protocols with Efficient Reconciliation
We study the equivalence between a realistic quantum key distribution
protocol using coherent states and homodyne detection and a formal entanglement
purification protocol. Maximally-entangled qubit pairs that one can extract in
the formal protocol correspond to secret key bits in the realistic protocol.
More specifically, we define a qubit encoding scheme that allows the formal
protocol to produce more than one entangled qubit pair per coherent state, or
equivalently for the realistic protocol, more than one secret key bit. The
entanglement parameters are estimated using quantum tomography. We analyze the
properties of the encoding scheme and investigate its application to the
important case of the attenuation channel.Comment: REVTeX, 11 pages, 2 figure
QKD in Standard Optical Telecommunications Networks
To perform Quantum Key Distribution, the mastering of the extremely weak
signals carried by the quantum channel is required. Transporting these signals
without disturbance is customarily done by isolating the quantum channel from
any noise sources using a dedicated physical channel. However, to really profit
from this technology, a full integration with conventional network technologies
would be highly desirable. Trying to use single photon signals with others that
carry an average power many orders of magnitude bigger while sharing as much
infrastructure with a conventional network as possible brings obvious problems.
The purpose of the present paper is to report our efforts in researching the
limits of the integration of QKD in modern optical networks scenarios. We have
built a full metropolitan area network testbed comprising a backbone and an
access network. The emphasis is put in using as much as possible the same
industrial grade technology that is actually used in already installed
networks, in order to understand the throughput, limits and cost of deploying
QKD in a real network
Strong asymptotics for Cauchy biorthogonal polynomials with application to the Cauchy two--matrix model
We apply the nonlinear steepest descent method to a class of 3x3
Riemann-Hilbert problems introduced in connection with the Cauchy two-matrix
random model. The general case of two equilibrium measures supported on an
arbitrary number of intervals is considered. In this case, we solve the
Riemann-Hilbert problem for the outer parametrix in terms of sections of a
spinorial line bundle on a three-sheeted Riemann surface of arbitrary genus and
establish strong asymptotic results for the Cauchy biorthogonal polynomials.Comment: 31 pages, 12 figures. V2; typos corrected, added reference
Matrix interpretation of multiple orthogonality
In this work we give an interpretation of a (s(d + 1) + 1)-term recurrence
relation in terms of type II multiple orthogonal polynomials.We rewrite
this recurrence relation in matrix form and we obtain a three-term recurrence
relation for vector polynomials with matrix coefficients. We present a matrix
interpretation of the type II multi-orthogonality conditions.We state a Favard
type theorem and the expression for the resolvent function associated to the
vector of linear functionals. Finally a reinterpretation of the type II Hermite-
Padé approximation in matrix form is given
Continuous variable private quantum channel
In this paper we introduce the concept of quantum private channel within the
continuous variables framework (CVPQC) and investigate its properties. In terms
of CVPQC we naturally define a "maximally" mixed state in phase space together
with its explicit construction and show that for increasing number of
encryption operations (which sets the length of a shared key between Alice and
Bob) the encrypted state is arbitrarily close to the maximally mixed state in
the sense of the Hilbert-Schmidt distance. We bring the exact solution for the
distance dependence and give also a rough estimate of the necessary number of
bits of the shared secret key (i.e. how much classical resources are needed for
an approximate encryption of a generally unknown continuous-variable state).
The definition of the CVPQC is analyzed from the Holevo bound point of view
which determines an upper bound of information about an incoming state an
eavesdropper is able to get from his optimal measurement.Comment: upper bound on information Eve can get was revised and substantially
lowered (chapter IV), part of chapter III rewritten, several typos correcte
Historic buildings and the creation of experiencescapes: looking to the past for future success
Purpose: The purpose of this paper is to identify the role that the creative re-use of historic buildings can play in the future development of the experiences economy. The aesthetic attributes and the imbued historic connotation associated with the building help create unique and extraordinary “experiencescapes” within the contemporary tourism and hospitality industries. Design/methodology/approach: This paper provides a conceptual insight into the creative re-use of historic buildings in the tourism and hospitality sectors, the work draws on two examples of re-use in the UK. Findings: This work demonstrates how the creative re-use of historic buildings can help create experiences that are differentiated from the mainstream hospitality experiences. It also identifies that it adds an addition unquantifiable element that enables the shift to take place from servicescape to experiencescape. Originality/value: There has been an ongoing debate as to the significance of heritage in hospitality and tourism. However, this paper provides an insight into how the practical re-use of buildings can help companies both benefit from and contribute to the experiences economy
Critical behavior in Angelesco ensembles
We consider Angelesco ensembles with respect to two modified Jacobi weights
on touching intervals [a,0] and [0,1], for a < 0. As a \to -1 the particles
around 0 experience a phase transition. This transition is studied in a double
scaling limit, where we let the number of particles of the ensemble tend to
infinity while the parameter a tends to -1 at a rate of order n^{-1/2}. The
correlation kernel converges, in this regime, to a new kind of universal
kernel, the Angelesco kernel K^{Ang}. The result follows from the Deift/Zhou
steepest descent analysis, applied to the Riemann-Hilbert problem for multiple
orthogonal polynomials.Comment: 32 pages, 9 figure
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