17,865 research outputs found
Laser induced THz emission from femtosecond photocurrents in Co/ZnO/Pt and Co/Cu/Pt multilayers
The ultrashort laser excitation of Co/Pt magnetic heterostructures can
effectively generate spin and charge currents at the interfaces between
magnetic and nonmagnetic layers. The direction of these photocurrents can be
controlled by the helicity of the circularly polarized laser light and an
external magnetic field. Here, we employ THz time-domain spectroscopy to
investigate further the role of interfaces in these photo-galvanic phenomena.
In particular, the effects of either Cu or ZnO interlayers on the photocurrents
in Co/X/Pt (X = Cu, ZnO) have been studied by varying the thickness of the
interlayers up to 5 nm. The results are discussed in terms of spin-diffusion
phenomena and interfacial spin-orbit torque.Comment: 15 pages, 6 figures, 2 table
Smoking among Hong Kong Chinese women: behavior, attitudes and experience
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Transformation of UML interaction diagrams into contract specifications for object-oriented testing
Testing is an important means to ensure the quality of software systems. Contract specification can be used to formally specify the cluster level of object-oriented software, which can then be tested using TACCLE, an advanced methodology for object-oriented testing. The use of formal specifications as a testing base has many advantages. However, such specifications are not easily understood and therefore not widely used in the software industry. On the other hand, UML, a semi-formal modeling language, is becoming increasingly popular and widely accepted. In particular, UML interaction diagrams specify the dynamic, interacting behavior among the objects of an object-oriented system. If the transformation of UML interaction diagrams into Contract specifications can be automated, the TACCLE methodology can be applied directly to test object-oriented software at the cluster level. In this paper, a method to transform UML interaction diagrams into Contract specifications is proposed based on the UML meta-model. A prototype has been developed. Β© 2007 IEEE.published_or_final_versio
Polynomial Growth Harmonic Functions on Finitely Generated Abelian Groups
In the present paper, we develop geometric analytic techniques on Cayley
graphs of finitely generated abelian groups to study the polynomial growth
harmonic functions. We develop a geometric analytic proof of the classical
Heilbronn theorem and the recent Nayar theorem on polynomial growth harmonic
functions on lattices \mathds{Z}^n that does not use a representation formula
for harmonic functions. We also calculate the precise dimension of the space of
polynomial growth harmonic functions on finitely generated abelian groups.
While the Cayley graph not only depends on the abelian group, but also on the
choice of a generating set, we find that this dimension depends only on the
group itself.Comment: 15 pages, to appear in Ann. Global Anal. Geo
Helping cancer patients quit smoking by increasing their risk perception: A study protocol of a cluster randomized controlled trial
BACKGROUND: Despite smoking cessation can largely improve cancer prognosis and quality of life, many patients continued smoking after the diagnosis of cancer. This study aims to test the effectiveness of a smoking cessation intervention using risk communication approach to help cancer patients quit smoking, and to improve their health related quality of life.
METHODS: A cluster randomized controlled trial will be employed. Cancer patients who continued smoking after the diagnosis of cancer and have medical follow-up at the out-patient clinics of the five acute hospitals in Hong Kong will be invited to participate. Subjects in the experimental group will receive (1) health warnings of smoking based on a special designed leaflet; and (2) a patient-centred counseling from nurse counselors with emphasis on risk perceptions of smoking to cancer prognosis. Additionally, they will receive two more telephone counseling at 1-week and 1-month. Control group receive standard care and a generic self-help smoking cessation booklet. Outcomes measure include (a) self-reported and the biochemically validated quit rate, (b) patient's smoking reduction by at least 50 % compared to baseline, (c) quit attempt(s), (d) change in the intention to quit, (e) change in risk perceptions of smoking, and (f) change in health related quality of life.
DISCUSSION: This study will make an important contribution to evidence-based practice by testing the effectiveness of a tailored smoking cessation intervention for cancer patients. The results will support the development of clinical practice guidelines to promote smoking cessation in cancer patients to improve their prognosis and quality of life.published_or_final_versio
Effectiveness of a parental training programme in enhancing the parent-child relationship and reducing harsh parenting practices and parental stress in preparing children for their transition to primary school: a randomised controlled trial
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Two isoperimetric inequalities for the Sobolev constant
In this note we prove two isoperimetric inequalities for the sharp constant
in the Sobolev embedding and its associated extremal function. The first such
inequality is a variation on the classical Schwarz Lemma from complex analysis,
similar to recent inequalities of Burckel, Marshall, Minda, Poggi-Corradini,
and Ransford, while the second generalises an isoperimetric inequality for the
first eigenfunction of the Laplacian due to Payne and Rayner.Comment: 11 page
Ni impurity induced enhancement of the pseudogap in cuprate high T_c superconductors
The influence of magnetic Ni and non-magnetic Zn impurities on the normal
state pseudogap (PG) in the c-axis optical conductivity of NdBa\{Cu(Ni,Zn)O crystals was studied by spectral
ellipsometry. We find that these impurities which strongly suppress
superconductivity have a profoundly different impact on the PG. Zn gives rise
to a gradual and inhomogeneous PG suppression while Ni strongly enhances the
PG. Our results challenge theories that relate the PG either to precursor
superconductivity or to other phases with exotic order parameters, such as flux
phase or d-density wave states, that should be suppressed by potential
scattering. The apparent difference between magnetic and non-magnetic
impurities instead points towards an important role of magnetic correlations in
the PG state.Comment: 11 pages and 2 figure
Hepatic fibrogenesis requires sympathetic neurotransmitters
Background and aims: Hepatic stellate cells (HSC) are activated by liver injury to become proliferative fibrogenic myofibroblasts. This process may be regulated by the sympathetic nervous system (SNS) but the mechanisms involved are unclear. Methods: We studied cultured HSC and intact mice with liver injury to test the hypothesis that HSC respond to and produce SNS neurotransmitters to promote fibrogenesis. Results: HSC expressed adrenoceptors, catecholamine biosynthetic enzymes, released norepinephrine (NE), and were growth inhibited by Ξ±- and Ξ²-adrenoceptor antagonists. HSC from dopamine Ξ²-hydroxylase deficient (Dbh(β/β)) mice, which cannot make NE, grew poorly in culture and were rescued by NE. Inhibitor studies demonstrated that this effect was mediated via G protein coupled adrenoceptors, mitogen activated kinases, and phosphatidylinositol 3-kinase. Injury related fibrogenic responses were inhibited in Dbh(β/β) mice, as evidenced by reduced hepatic accumulation of Ξ±-smooth muscle actin(+ve) HSC and decreased induction of transforming growth factor Ξ²1 (TGF-Ξ²1) and collagen. Treatment with isoprenaline rescued HSC activation. HSC were also reduced in leptin deficient ob/ob mice which have reduced NE levels and are resistant to hepatic fibrosis. Treating ob/ob mice with NE induced HSC proliferation, upregulated hepatic TGF-Ξ²1 and collagen, and increased liver fibrosis. Conclusions: HSC are hepatic neuroglia that produce and respond to SNS neurotransmitters to promote hepatic fibrosis
An evaluation study of a gender-specific smoking cessation program to help Hong Kong Chinese women quit smoking
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