18,782 research outputs found
Entanglement Entropy of One-dimensional Gapped Spin Chains
We investigate the entanglement entropy (EE) of gapped S=1 and spin
chains with dimerization. We find that the effective boundary degrees of
freedom as edge states contribute significantly to the EE. For the
dimerized Heisenberg chain, the EE of the sufficiently long chain is
essentially explained by the localized effective spins on the
boundaries. As for S=1, the effective spins are also causing a Kennedy
triplet that yields a lower bound for the EE. In this case, the residual
entanglement reduces substantially by a continuous deformation of the
Heisenberg model to that of the AKLT Hamiltonian.Comment: 5 pages, 6 figure
Entanglement of light-shift compensated atomic spin waves with telecom light
Entanglement of a 795 nm light polarization qubit and an atomic Rb spin wave
qubit for a storage time of 0.1 s is observed by measuring the violation of
Bell's inequality (S = 2.65 \pm 0.12). Long qubit storage times are achieved by
pinning the spin wave in a 1064 nm wavelength optical lattice, with a
magic-valued magnetic field superposed to eliminate lattice-induced dephasing.
Four-wave mixing in a cold Rb gas is employed to perform light qubit conversion
between near infra red (795 nm) and telecom (1367 nm) wavelengths, and after
propagation in a telecom fiber, to invert the conversion process. Observed Bell
inequality violation (S = 2.66 \pm 0.09), at 10 ms storage, confirms
preservation of memory/light entanglement through the two stages of light qubit
frequency conversion.Comment: 5 pages, 3 figure
The motivating operation and negatively reinforced problem behavior. A systematic review.
The concept of motivational operations exerts an increasing influence on the understanding and assessment of problem behavior in people with intellectual and developmental disability. In this systematic review of 59 methodologically robust studies of the influence of motivational operations in negative reinforcement paradigms in this population, we identify themes related to situational and biological variables that have implications for assessment, intervention, and further research. There is now good evidence that motivational operations of differing origins influence negatively reinforced problem behavior, and that these might be subject to manipulation to facilitate favorable outcomes. There is also good evidence that some biological variables warrant consideration in assessment procedures as they predispose the person's behavior to be influenced by specific motivational operations. The implications for assessment and intervention are made explicit with reference to variables that are open to manipulation or that require further research and conceptualization within causal models
Resonant states in an attractive one dimensional cusp potential
We solve the two-component Dirac equation in the presence of a spatially one
dimensional symmetric attractive cusp potential. The components of the spinor
solution are expressed in terms of Whittaker functions. We compute the bound
states solutions and show that, as the potential amplitude increases, the
lowest energy state sinks into the Dirac sea becoming a resonance. We
characterize and compute the lifetime of the resonant state with the help of
the phase shift and the Breit-Wigner relation. We discuss the limit when the
cusp potential reduces to a delta point interaction.Comment: 11 pages. To appear in Physica Script
Utility of novel viral and immune markers in predicting HBV treatment endpoints: A systematic review of treatment discontinuation studies.
BACKGROUND & AIMS: Antivirals represent the mainstay of chronic hepatitis B treatment given their efficacy and tolerability, but rates of functional cure remain low during long-term therapy. Treatment discontinuation has emerged as a strategy to maintain partial cure and achieve functional cure in select patient groups. We aimed to evaluate how data from treatment discontinuation studies exploring novel viral and/or immune markers could be applied to the functional cure program. METHODS: Treatment discontinuation studies evaluating novel viral and/or immune markers were identified by a systematic search of the PubMed database through to October 30, 2022. Data extraction focused on information regarding novel markers, including identified cut-off levels, timing of measurement, and associated effect on study outcomes of virological relapse, clinical relapse, and HBsAg seroclearance. RESULTS: From a search of 4,492 citations, 33 studies comprising a minimum of 2,986 unique patients met the inclusion criteria. Novel viral markers, HBcrAg and HBV RNA, were demonstrated across most studies to be helpful in predicting off-therapy partial cure, with emerging evidence to support a link with functional cure. From novel immune marker studies, we observed that treatment discontinuation has the potential to trigger immune restoration, which may be associated with a transient virological relapse. To this end, these studies support the combination of virus-directing agents with immunomodulator therapies to induce two key steps underlying functional cure: viral antigen load reduction and restoration of the host immune response. CONCLUSIONS: Patients with a favourable profile of novel viral and immune markers stand to benefit from a trial of antiviral treatment discontinuation alongside novel virus-directing agents with the aim of achieving functional cure without excessive risk of severe clinical relapse. IMPACT AND IMPLICATIONS: Select patients with chronic hepatitis B undergoing nucleoside analogue therapy may benefit from a trial of treatment discontinuation, aiming to maintain partial cure and/or achieve functional cure. We propose a profile of novel viral and immune markers to identify patients who are likely to achieve these goals without excessive risk of hepatic decompensation. Furthermore, treatment discontinuation may also be considered as a therapeutic strategy to trigger immune restoration, which may increase the chance of functional cure when used in conjunction with novel virus-directing agents
First passage times and distances along critical curves
We propose a model for anomalous transport in inhomogeneous environments,
such as fractured rocks, in which particles move only along pre-existing
self-similar curves (cracks). The stochastic Loewner equation is used to
efficiently generate such curves with tunable fractal dimension . We
numerically compute the probability of first passage (in length or time) from
one point on the edge of the semi-infinite plane to any point on the
semi-circle of radius . The scaled probability distributions have a variance
which increases with , a non-monotonic skewness, and tails that decay
faster than a simple exponential. The latter is in sharp contrast to
predictions based on fractional dynamics and provides an experimental signature
for our model.Comment: 5 pages, 5 figure
Nothing to Sneeze at: Histamine and Histamine Receptors in Oral Carcinogenesis
Oral squamous cell carcinoma (OSCC), the most common oral malignancy, shows an increasing rate of incidence worldwide. In spite of the recent advances in cancer research, OSCC therapy continues to have unfavourable outcomes, and thus patient’s prognosis remains relatively poor. Current research has been devoted to identifying novel therapeutic targets also in the tumour microenvironment (TME). Histamine and its G-protein coupled receptors (H1R-H4R) play vital roles in multiple cancer-associated processes in TME, where histamine is mainly produced by mast cells. However, oral epithelial cells were recently shown to produce low concentrations of histamine in autocrine and paracrine modes. These findings, together with the discovery of the high-affinity histamine H4 receptor, have led to a massive increase in our understanding of histamine functions. This minireview aims to summarize the most recent findings regarding histamine and its receptors and their involvement in oral carcinogenesis—from oral potentially malignant disorders (OPMDs) to invasive OSCC. Importantly, histamine receptors are differentially expressed in OPMDs and OSCC. Furthermore, H1R and H4R are associated with clinicopathological characteristics of OSCC patients, suggesting a role in prognosis. Due to the enormous success of histamine-based medications, histamine receptors may also represent promising and viable drug targets in oral cancer.Peer reviewe
A family of diameter-based eigenvalue bounds for quantum graphs
We establish a sharp lower bound on the first non-trivial eigenvalue of the
Laplacian on a metric graph equipped with natural (i.e., continuity and
Kirchhoff) vertex conditions in terms of the diameter and the total length of
the graph. This extends a result of, and resolves an open problem from, [J. B.
Kennedy, P. Kurasov, G. Malenov\'a and D. Mugnolo, Ann. Henri Poincar\'e 17
(2016), 2439--2473, Section 7.2], and also complements an analogous lower bound
for the corresponding eigenvalue of the combinatorial Laplacian on a discrete
graph. We also give a family of corresponding lower bounds for the higher
eigenvalues under the assumption that the total length of the graph is
sufficiently large compared with its diameter. These inequalities are sharp in
the case of trees.Comment: Substantial revision of v1. The main result, originally for the first
eigenvalue, has been generalised to the higher ones. The title has been
changed and the proofs substantially reorganised to reflect the new result,
and a section containing concluding remarks has been adde
Collective excitation spectrum of a disordered Hubbard model
We study the collective excitation spectrum of a d=3 site-disordered
Anderson-Hubbard model at half-filling, via a random-phase approximation (RPA)
about broken-symmetry, inhomogeneous unrestricted Hartree-Fock (UHF) ground
states. We focus in particular on the density and character of low-frequency
collective excitations in the transverse spin channel. In the absence of
disorder, these are found to be spin-wave-like for all but very weak
interaction strengths, extending down to zero frequency and separated from a
Stoner-like band, to which there is a gap. With disorder present, a prominent
spin-wave-like band is found to persist over a wide region of the
disorder-interaction phase plane in which the mean-field ground state is a
disordered antiferromagnet, despite the closure of the UHF single-particle gap.
Site resolution of the RPA excitations leads to a microscopic rationalization
of the evolution of the spectrum with disorder and interaction strength, and
enables the observed localization properties to be interpreted in terms of the
fraction of strong local moments and their site-differential distribution.Comment: 25 pages (revtex), 9 postscript figure
Robotic TAPP Ventral Hernia Repair: Early Lessons Learned at an Inner City Safety Net Hospital
- …