1,256 research outputs found

    Statistics of level spacing of geometric resonances in random binary composites

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    We study the statistics of level spacing of geometric resonances in the disordered binary networks. For a definite concentration pp within the interval [0.2,0.7][0.2,0.7], numerical calculations indicate that the unfolded level spacing distribution P(t)P(t) and level number variance Σ2(L)\Sigma^2(L) have the general features. It is also shown that the short-range fluctuation P(t)P(t) and long-range spectral correlation Σ2(L)\Sigma^2(L) lie between the profiles of the Poisson ensemble and Gaussion orthogonal ensemble (GOE). At the percolation threshold pcp_c, crossover behavior of functions P(t)P(t) and % \Sigma^2(L) is obtained, giving the finite size scaling of mean level spacing δ\delta and mean level number nn, which obey the scaling laws, % \delta=1.032 L ^{-1.952} and n=0.911L1.970n=0.911L^{1.970}.Comment: 11 pages, 7 figures,submitted to Phys. Rev.

    Serum adiponectin in relation to other obesity-related biomarkers in predicting type 2 diabetes: a 5-year prospective study

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    Oral PresentationAIMS: To identify obesity-related serum biomarkers associated with the development of type 2 diabetes in a Chinese population and to examine if these biomarkers added values to conventional risk factors in diabetes prediction. METHODS: We studied 1315 non-diabetic subjects from the prospective Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS). Serum biomarkers including adiponectin, tumour necrosis …published_or_final_versionThe 17th Medical Research Conference, The University of Hong Kong, Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 suppl. 1, p. 57, abstract no. 8

    Predictors common to cardiovascular and cancer outcomes in a population-based 13-year prospective study in Hong Kong

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    Oral PresentationINTRODUCTION: Cardiovascular diseases (CVD) and cancer are the two leading causes of death in Hong Kong. Obesity is becoming increasingly prevalent in the local population and has been reported to be associated with CVD and some forms of cancer in the western world. In this study, we attempted to identify the aetiological factors linking obesity to both CVD and cancer among Hong Kong Chinese. METHODS: Subjects were recruited from the Hong Kong Cardiovascular Risk Factor Prevalence Study (CRISPS) …published_or_final_versionThe 16th Medical Research Conference, The University of Hong Kong, Hong Kong, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17 suppl. 1, p. 56, abstract no. 9

    Images of the Dark Soliton in a Depleted Condensate

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    The dark soliton created in a Bose-Einstein condensate becomes grey in course of time evolution because its notch fills up with depleted atoms. This is the result of quantum mechanical calculations which describes output of many experimental repetitions of creation of the stationary soliton, and its time evolution terminated by a destructive density measurement. However, such a description is not suitable to predict the outcome of a single realization of the experiment were two extreme scenarios and many combinations thereof are possible: one will see (1) a displaced dark soliton without any atoms in the notch, but with a randomly displaced position, or (2) a grey soliton with a fixed position, but a random number of atoms filling its notch. In either case the average over many realizations will reproduce the mentioned quantum mechanical result. In this paper we use N-particle wavefunctions, which follow from the number-conserving Bogoliubov theory, to settle this issue.Comment: 8 pages, 6 figures, references added in version accepted for publication in J. Phys.

    Lipid profile of the Hong Kong Cardiovascular Risk Factor Prevalence Study cohort

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    Single photon generation by pulsed excitation of a single dipole

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    The fluorescence of a single dipole excited by an intense light pulse can lead to the generation of another light pulse containing a single photon. The influence of the duration and energy of the excitation pulse on the number of photons in the fluorescence pulse is studied. The case of a two-level dipole with strongly damped coherences is considered. The presence of a metastable state leading to shelving is also investigated.Comment: 17 pages, 4 figures, submitted to PR

    Adenoid cystic carcinoma intermingled with ductal carcinoma of the breast: a case report and review of the literature

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    <p>Abstract</p> <p>Introduction</p> <p>Adenoid cystic cancer of the breast is a rare condition, and even rarer are the cases where it is histologically mixed with other variants of cancer within a single lesion. In this report, one of the few cases of mixed adenoid cystic breast cancer intermingled with the infiltrating ductal variant is presented. A subsequent review of the relevant literature presents the existing experience in treating mixed breast cancers with adenoid cystic components with regard to diagnosis, treatment, and prognosis.</p> <p>Case presentation</p> <p>We describe a case of mixed adenoid cystic cancer of the breast with infiltrating ductal carcinoma in a 67-year-old Caucasian woman who underwent mastectomy with sentinel node biopsy.</p> <p>Conclusion</p> <p>Surgery remains the cornerstone of treatment of these patients, and radiotherapy is administered when breast-conserving treatment is undertaken or a large tumor with affected lymph nodes is present. Hormonal treatment does not have a role, as estrogen receptors are always absent from both tumor components. Chemotherapy is nearly always administered on the basis of estrogen receptor and progesterone negativity and the more aggressive potential of the non-adenoid cystic component. The de-differentiation of an indolent type of cancer to a more aggressive one may affect the prognosis.</p

    Carbon enrichment of the evolved stars in the Sagittarius dwarf spheroidal

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    We present spectra of 1142 colour-selected stars in the direction of the Sagittarius Dwarf Spheroidal (Sgr dSph) galaxy, of which 1058 were taken with VLT/FLAMES multi-object spectrograph and 84 were taken with the SAAO Radcliffe 1.9-m telescope grating spectrograph. Spectroscopic membership is confirmed (at >99% confidence) for 592 stars on the basis of their radial velocity, and spectral types are given. Very slow rotation is marginally detected around the galaxy's major axis. We identify five S stars and 23 carbon stars, of which all but four carbon stars are newly-determined and all but one (PQ Sgr) are likely Sgr dSph members. We examine the onset of carbon-richness in this metal-poor galaxy in the context of stellar models. We compare the stellar death rate (one star per 1000-1700 years) to known planetary nebula dynamical ages and find that the bulk population produce the observed (carbon-rich) planetary nebulae. We compute average lifetimes of S and carbon stars as 60-250 and 130-500 kyr, compared to a total thermal-pulsing asymptotic giant branch lifetime of 530-1330 kyr. We conclude by discussing the return of carbon-rich material to the ISM.Comment: 14 pages, 10 figures, accepted MNRA
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