640 research outputs found
Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential
We study the Stell-Hemmer potential using both analytic (exact and
approximate ) solutions and numerical simulations. We observe in the
liquid phase an anomalous decrease in specific volume and isothermal
compressibility upon heating, and an anomalous increase in the diffusion
coefficient with pressure. We relate the anomalies to the existence of two
different local structures in the liquid phase. Our results are consistent with
the possibility of a low temperature/high pressure liquid-liquid phase
transition.Comment: 4 pages in one gzipped ps file including 11 figures; One RevTex and
11 gzipped eps figure
Matter Wave Scattering and Guiding by Atomic Arrays
We investigate the possibility that linear arrays of atoms can guide matter
waves, much as fiber optics guide light. We model the atomic line as a quasi-1D
array of s wave point scatterers embedded in 2D. Our theoretical study reveals
how matter wave guiding arises from the interplay of scattering phenomena with
bands and conduction along the array. We discuss the conditions under which a
straight or curved array of atoms can guide a beam focused at one end of the
array.Comment: Submitted to Phys. Rev.
Radial solitons in armchair carbon nanotubes
Radial solitons are investigated in armchair carbon nanotubes using a
generalized Lennard-Jones potential. The radial solitons are found in terms of
moving kink defects whose velocity obeys a dispersion relation. Effects of
lattice discreteness on the shape of kink defects are examined by estimating
the Peierls stress. Results suggest that the typical size for an unpinned kink
phase is of the order of a lattice spacing.Comment: 11 pages, 3(eps) figure
The multidisciplinary, theory-based co-design of a new digital health intervention supporting the care of oesophageal cancer patients
Objective:
Oesophageal cancer patients have complex care needs. Cancer clinical nurse specialists play a key role in coordinating their care but often have heavy workloads. Digital health interventions can improve patient care but there are few examples for oesophageal cancer. This paper aims to describe the multidisciplinary co-design process of a digital health intervention to improve the experience of care and reduce unmet needs among patients with oesophageal cancer.
Methods:
A theory-based, multi-disciplinary, co-design approach was used to inform the developmental process of the digital health intervention. Key user needs were elicited using mixed methodology from systematic reviews, focus groups and interviews and holistic need assessments. Overarching decisions were discussed among a core team of patients, carers, health care professionals including oncologists and cancer clinical nurse specialists, researchers and digital health providers. A series of workshops incorporating a summary of findings of key user needs resulted in the development of a minimum viable product. This was further refined after a pilot study based on feedback from end users.
Results:
The final digital health intervention consists of a mobile app feature for patients and carers connected to a dashboard with supporting additional features for clinical nurse specialist. It contains a one-way messaging function for clinical nurse specialists to communicate with patients, functions for patients to record weight and holistic need assessment results which could be viewed by their clinical nurse specialists as well as a library of informative articles.
Conclusions:
The multidisciplinary co-design of a digital health intervention providing support for oesophageal cancer patients and health care professionals has been described. Future studies to establish its impact on patient outcomes are planned
Casimir-Polder interaction between an excited atom and a gas dielectric medium
The Casimir-Polder potential for interaction between an excited atom and a
ground-state one in the retarded case obtained with the help of perturbation
technique drops as R^-2 with the distance between the atoms [E.A. Power,
T.Thirunamachandran, Phys. Rev. A, 47, 2539 (1993)]. It results in diverdent
integrals for interaction between an excited atom and a dilute gas medium. We
investigate interaction between two atoms embedded in a dielectric medium with
the help of non-perturbative approach. We take into account absorption of
photons in the medium. This approach solves the problem of divergence. We
consider interaction between an excited atom and a planar dielectric gas medium
of ground-state atoms. We show that the retarded interaction between an excited
atom and a gas of ground-state atoms is not oscillating but follows a simple
power law. We show that to obtain coventional non-retarded expression for the
van der Waals force between an excited atom and a dilute gas the distance
between the atom and the interface should be much smaller than the free mean
pass of a photon in the medium. Interaction between an excited atom and a
hemisphere of ground-state atoms is considered.Comment: 23 pages, 6 figure
Using atomic interference to probe atom-surface interaction
We show that atomic interference in the reflection from two suitably
polarized evanescent waves is sensitive to retardation effects in the
atom-surface interaction for specific experimental parameters. We study the
limit of short and long atomic de Broglie wavelength. The former case is
analyzed in the semiclassical approximation (Landau-Zener model). The latter
represents a quantum regime and is analyzed by solving numerically the
associated coupled Schroedinger equations. We consider a specific experimental
scheme and show the results for rubidium (short wavelength) and the much
lighter meta-stable helium atom (long wavelength). The merits of each case are
then discussed.Comment: 11 pages, including 6 figures, submitted to Phys. Rev. A, RevTeX
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High-dose chemotherapy and autologous stem cell transplantation in enteropathy-associated and other aggressive T-cell lymphomas: a UK NCRI/Cancer Research UK Phase II Study
Theory and simulation of short-range models of globular protein solutions
We report theoretical and simulation studies of phase coexistence in model
globular protein solutions, based on short-range, central, pair potential
representations of the interaction among macro-particles. After reviewing our
previous investigations of hard-core Yukawa and generalised Lennard-Jones
potentials, we report more recent results obtained within a DLVO-like
description of lysozyme solutions in water and added salt. We show that a
one-parameter fit of this model based on Static Light Scattering and
Self-Interaction Chromatography data in the dilute protein regime, yields
demixing and crystallization curves in good agreement with experimental
protein-rich/protein-poor and solubility envelopes. The dependence of cloud and
solubility points temperature of the model on the ionic strength is also
investigated. Our findings highlight the minimal assumptions on the properties
of the microscopic interaction sufficient for a satisfactory reproduction of
the phase diagram topology of globular protein solutions.Comment: 17 pages, 8 figures, Proc. of Conference "Structural Arrest
Transitions in Colloidal Systems with Short-Range Attractions", Messina
(ITALY) 17-20 December 200
Metallothionein genes: no association with Crohn's disease in a New Zealand population
Metallothioneins (MTs) are excellent candidate genes for Inflammatory Bowel Disease (IBD) and have previously been shown to have altered expression in both animal and human studies of IBD. This is the first study to examine genetic variants within the MT genes and aims to determine whether such genetic variants have an important role in this disease. 28 tag SNPs in genes MT1 (subtypes A, B, E, F, G, H, M, X), MT2, MT3 and MT4 were selected for genotyping in a well-characterized New Zealand dataset consisting of 406 patients with Crohn's Disease and 638 controls. We did not find any evidence of association for MT genetic variation with CD. The lack of association indicates that genetic variants in the MT genes do not play a significant role in predisposing to CD in the New Zealand population
Structural and Electronic Instabilities in Polyacenes: Density Matrix Renormalization Group Study of a Long--Range Interacting Model
We have carried out Density Matrix Renormalization Group (DMRG) calculations
on the ground state of long polyacene oligomers within a Pariser-Parr-Pople
(PPP) Hamiltonian. The PPP model includes long-range electron correlations
which are required for physically realistic modeling of conjugated polymers. We
have obtained the ground state energy as a function of the dimerization
and various correlation functions and structure factors for
. From energetics, we find that while the nature of the Peierls'
instabilityin polyacene is conditional and strong electron correlations enhance
the dimerization. The {\it cis} form of the distortion is favoured over the
{\it trans} form. However, from the analysis of correlation functions and
associated structure factors, we find that polyacene is not susceptible to the
formation of a bond order wave (BOW), spin density wave (SDW) or a charge
density wave (CDW) in the ground state.Comment: 31 pages, latex, 13 figure
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