bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precision of risk in multidimensional likelihood ratio based screening with first trimester screening for Down's syndrome as a special case
Authors: Christiansen M. , Larsen S.O. 
Published: October 2002

Objectives The development of computer programs for the calculation of risks and Monte Carlo estimation of the precision of such risks in likelihood ratio based screening with multiple gaussian distributed risk markers and a priori risks. A quantitative study of the variation of risk estimates in first trimester screening for Down's syndrome as a function of the variation of markers, and comparison of the results with published information on the variation of risk estimates in quality control schemes. Methods Algorithms for calculations in the multidimensional normal distribution and procedures for Monte Carlo simulation of risk distributions were implemented in the S-PLUS programming language and used to construct programs producing risk estimates and risk distributions. Parameters of risk marker distributions and correlations were obtained from the scientific literature. Results In screening for Down's syndrome during the first trimester the variation in risk estimates increased with increasing variation of biochemical and biometric markers, and the a posteriori risk may vary with at least a factor of 2–4. Conclusions Risk estimates are not reasonable parameters in quality control systems. Instead, screening programmes should be controlled through careful monitoring of the distribution of risk estimates, in particular the screen positive rate, and control of the quality of the biochemical and biometric data. Furthermore, the correct classification of samples submitted for proficiency testing into screen positive and screen negative cases should be checked.
Cluster randomised controlled trial comparing the effectiveness and cost-effectiveness of two primary care interventions aimed at improving attendance for breast screening
Authors: Richards S.H. , Bankhead C. , Peters T.J. , Austoker J. , Hobbs F.D.R. , Brown J. , Tydeman C. , Roberts L. , Formby J. , Redman V. , Wilson S. , Sharp D.J. 
Published: October 2002

Objectives To examine the effectiveness and cost-effectiveness of two interventions based in primary care aimed at increasing uptake of breast screening. Setting 24 General practices with low uptake in the second round of screening (below 60%) in north west London and the West Midlands, UK. Participants were all women registered with these practices and eligible for screening in the third round. Methods Pragmatic factorial cluster randomised controlled trial, with practices randomised to a systematic intervention (general practitioner letter), an opportunistic intervention (flag in women's notes prompting discussion by health professionals), neither intervention, or both. Outcome measures were attendance for screening 6 months after the practices had been screened and cost-effectiveness of the interventions. Results 6133 Women were included: 1721 control; 1818 letter; 1232 flag; 1362 both interventions. Attendance data were obtained for 5732 (93%) women. The two interventions independently increased breast screening uptake in a logistic regression model adjusted for clustering, with the flag (odds ratio (OR) 1.43, 95% confidence interval (95% CI) 1.14 to 1.79; p=0.0019) marginally more effective than the letter (OR 1.31, 95% CI 1.05 to 1.64; p=0.015). Health service costs per additional attendance were £26 (letter) and £41 (flag). Conclusions Although both interventions increased attendance for breast screening, the letter was the more cost-effective. Any decision to implement both interventions rather than just the letter will depend on whether the additional (£41) costs are judged worthwhile in terms of the gains in breast screening uptake.
Systemic sclerosis and occupational risk factors: a case–control study
Authors: Diot E , Lesire V , Guilmot J L , Metzger M D , Pilore R , Rogier S , Stadler M , Diot P , Lemarie E , Lasfargues G 
Published: October 2002

Aims:A case–control study was carried out between 1998 and 2000 to investigate the relation between systemic sclerosis and occupational exposure.Methods:Eighty cases of systemic sclerosis admitted consecutively to the Department of Internal Medicine at the University Hospital of Tours from 1998 to 2000 were included. For each case, two age, gender, and smoking habits matched controls hospitalised during the same period in the same department were selected. A committee of experts was set up retrospectively to assess occupational exposure. Exposure to silica dust and organic solvents (such as trichlorethylene and other chlorinated solvents, and benzene and other aromatic solvents) was investigated using semiquantitative estimates of exposure. An exposure score was calculated for each subject based on probability, intensity, daily frequency, and duration of exposure for each period of employment. The final cumulative exposure score was obtained, taking into account all periods of employment.Results:Significant associations with SS were observed for crystalline silica, trichlorethylene, chlorinated solvents, toluene, aromatic solvents, ketones, white spirit, epoxy resins, and welding fumes. Risk of SS was significantly associated with a high final cumulative exposure score of occupational exposure to crystalline silica, trichlorethylene, chlorinated solvents, welding fumes, and any types of solvents.Conclusion:Results confirm the influence of occupational risk factors in the occurrence of SS in both men and women. The link is not only with silica but also with other compounds such as solvents.
Management of colorectal cancer
Authors: Leslie A , Steele R J C 
Published: October 2002

AbstractColorectal cancer is the second most common cause of cancer death in the UK. Prompt investigation of suspicious symptoms is important, but there is increasing evidence that screening for the disease can produce significant reductions in mortality. High quality surgery is of paramount importance in achieving good outcomes, particularly in rectal cancer, but adjuvant radiotherapy and chemotherapy have important parts to play. The treatment of advanced disease is still essentially palliative, although surgery for limited hepatic metastases may be curative in a small proportion of patients.
Unusual cardiac manifestation of hypereosinophilic syndrome
Authors: Subhash H S , Asishkumar M , Jonathan M 
Published: October 2002

Abstract
Hypereosinophilic syndrome was diagnosed in a 14 year old girl who presented with recurrent syncope. An ambulatory electrocardiogram revealed intermittent type 2 second degree left atrioventricular (AV) block. Focal thinning of the interventricular septum was noted on echocardiography, contrary to the commoner finding of regional ventricular wall thickening among patients with hypereosinophilic syndrome. High grade AV block as a manifestation of hypereosinophilic syndrome is rare and focal thinning of the left ventricle as a manifestation of the syndrome has not been described earlier.
Multifocal cardiac leiomyosarcoma. Diagnosis and surveillance by transoesophageal echocardiography and contrast enhanced cardiovascular magnetic resonance
Authors: Clarke N R A , Mohiaddin R H , Westaby S , Banning A P 
Published: October 2002

Abstract
Primary cardiac sarcomas are rare and typically undergo aggressive local spread. There is no reliable definitive treatment, although radical surgical resection can provide palliation in the medium term. A case of a pleomorphic leiomyosarcoma with dramatic images is presented. The relative usefulness of transoesophageal echocardiography and cardiovascular magnetic resonance imaging to define the extent of tumour involvement, allowing planning of treatment, is demonstrated.
Nonresonant effects in one- and two-photon transitions
Authors: Jentschura U D , Mohr P J 
Published: October 2002

We investigate nonresonant contributions to resonant Rayleigh-scattering cross sections of atoms. The problematic nonresonant contributions set a limit to the accuracy to which atomic spectra determine energy levels. We discuss the off-resonance effects in one-photon transitions. We also show that off-resonance contributions for the 1S2S two-photon transition in atomic hydrogen are negligible at current and projected levels of experimental accuracy. The possibility of a differential measurement for the detection of off-resonance effects in one-photon transitions in atomic hydrogen is discussed. PACS Nos.: 31.15-p, 12.20Ds
Diffraction by a set of three parallel impedance half-planes with the one amidst located in the opposite direction
Authors: Çinar G , Büyükaksoy A 
Published: October 2002

The problem of diffraction of plane waves by a set of three parallel half-planes with different surface impedances on upper and lower faces where the one in the middle is placed in the opposite direction, is solved by the mode-matching method where available, and by Fourier-transform technique elsewhere. The solution includes two independent WienerHopf equations each involving an infinite number of expansion coefficients that satisfy an infinite system of linear algebraic equations. PACS No.: 41.20J
Localization of a bound particle outside the potential well
Authors: Holub R F , Smrz P K 
Published: October 2002

We describe a simple effect predicted by standard quantum mechanics concerning a particle bound in a potential well brought to the zero-energy state by deformation of the well. When the effect takes place within a crack with impermeable walls the probability of localization of the particle reaches its maximum near the end of the crack. The wave function describing the bound particle may thus decohere far from the potential well. There are numerous instances of experimental data, gathered mostly by geochemists and other scientists over the last several decades, that are anomalous and defy all attempts to explain them by means of classical chemistry and physics. The common attribute of these data is a strange transport of particles over large distances that may be caused by the quantum effect described in the first part of the paper. The motivation for writing this paper is our hope to stimulate interest and critical testing of such an hypothesis. PACS Nos.: 03.65, 82.90, 91.90
METABOLIC NETWORKS FROM (ℳ, ℛ) SYSTEMS AND AUTOPOIESIS PERSPECTIVE
Authors: ZARETZKY ALBA N. , LETELIER JUAN C. 
Published: October 2002

This paper is the first one of a series devoted to the analysis of metabolic networks. Its aim is to establish the theoretical framework for this analysis. Two different lines of research are considered: the one about metabolism-repair systems ((ℳ, ℛ)), introduced by Robert Rosen as an abstract representation of cell metabolic activity, and the concept of autopoiesis developed by Humberto Maturana and Francisco Varela. Both concepts have been recently connected by Letelier et al., determining that the set of autopoietic systems is a subset of the set of general abstract (ℳ, ℛ) systems. In fact, every specific (ℳ, ℛ) system is an autopoietic one, being the boundary, which specifies each system as a unity, the main element of autopoietic systems which is not formalized in Rosen's representation. This paper introduces the definition of boundary — a physical boundary and a functional one — for (ℳ, ℛ) systems in the context of a representation using category theory. The concept of complete (ℳ, ℛ) system is also introduced by means of a process of completion in categories which is functorial, natural and universal.
OPTICAL PROPERTIES OF GLASSY CARBON
Authors: PAJASOVÁ L. , SOUKUP L. , JASTRABÍK L. , CHVOSTOVÁ D. 
Published: October 2002

The optical constants and dielectric functions of a series of samples of glassy carbon subjected to a heat treatment from 1000°C to 3000°C have been evaluated in the spectral region of 1.5–13.8 eV. In the region of 1.5–5.0 eV the method of spectroscopic ellipsometry and multiangle reflectivity with p-polarized light was applied, while in the VUV region the optical constants were evaluated by means of multiangle reflectivity with partially polarized light as well as by means of Kramers–Kronig analysis. The optical spectra are discussed, in analogy with graphite, in terms of single-electron transitions and π electron plasma excitations. The changes in the spectra by heating are ascribed to increasing average size of ordered regions and sample densification in the absence of three-dimensional graphitization.
INFLUENCE OF OPTICAL PROPERTIES ON THE SPIN POLARIZATION OF Cu3P PHOTOELECTRONS
Authors: CHASSÉ A. , NIEBERGALL L. 
Published: October 2002

We have investigated the influence of optical properties of Cu(001) on the spin polarization in Cu 3p photoelectron diffraction patterns. The refraction and absorption of light have been taken into account in the calculation of the dipole transition matrix element. Therefore, a general polarization vector of light is defined within a macroscopic theory of electromagnetic fields. Results are shown and discussed for Cu 3p photoelectrons excited by linearly or circularly polarized light, respectively. It is shown that the optical behavior of crystals may cause a symmetry breaking in the angular dependence of the photoelectron intensity. Besides, there are strong quantitative changes in the related spin polarization of Cu 3p photoelectrons.
OPTICAL ABSORPTION AND LUMINESCENCE OF C60F2X COMPOUNDS
Authors: DUDIN P. V. , AMARANTOV S. V. , STANKEVITCH V. G. , BEZMELNITSYN V. N. , RYZKOV A. V. , BOLTALINA O. V. , DANAILOV M. B. 
Published: October 2002

We have investigated the reduction of initial C 60 electronic structure under the influence of a growing number of attached fluorines in C 60 F 48, C 60 F 36, C 60 F 24, and C 60 F 18. The reduction of the low-energy π-electron subsystem reveals itself in lowering of the optical absorption in the visible region and in gradual blueshift of the luminescence. The absorption of C 60 F 24 and C 60 F 18 films strongly resembles that of C 60, thus showing the similarity of electronic structures of C 60 and these compounds. This resemblance disappears in the absorption spectra of C 60 F 48 and C 60 F 36. The absorption of these compounds looks like that of C 6 H 6, because the π-bonds are isolated. The luminescence of C 60 F 18 film has an unexpected two-component structure, with the first component close to the C 60 luminescence spectra, and the second one lying pproximately in the same region with C 60 F 36. We attribute this splitting of luminescence spectra to the two different channels for relaxation of the electronic excitation. The first one is correlated with the fluorinated part of the C 60 F 18 molecule, the second one with the part free of fluorine atoms.
CHARACTERIZATION OF COADSORBED MOLECULAR SPECIES IN A MULTILAYER SOLVENT ENVIRONMENT ON INSULATING SURFACES
Authors: GÜNSTER J. , KRISCHOK S. , KEMPTER V. , STULTZ J. , GOODMAN D. W. 
Published: October 2002

By employing metastable impact electron spectroscopy (MIES) and ultraviolet photoelectron spectroscopy (UPS, HeI) together with work function measurements and temperature-programmed desorption (TPD), the condensation of multilayer solvent systems, such as water and methanol on ultrathin Mo(100)-supported MgO films, has been investigated. In a first step, the techniques MIES/UPS and TPD are used to characterize the condensation of the pure solvent systems. Data collected in a coverage regime from submono- to multilayers at substrate temperatures between 100 and 500 K are surveyed in order to provide information about the buildup of the multilayer systems on an atomic level. Besides investigating the chemistry of pure phases, the present work provides insight into the chemistry of coadsorbed molecular species in a multilayer solvent environment. It is shown that thin films of amorphous water prepared at 100 K are a good candidate for studying aqueous multilayer chemistry under well-defined conditions, i.e. ultrahigh vacuum, by MIES. We are taking advantage of the unique properties of amorphous water films for investigating the interaction of water with coadsorbates, such as sodium and methanol. A deliberately chosen surface preparation technique in combination with the surface-sensitive electron-spectroscopic technique MIES enables the discrimination of various stages in the complex coadsorbate multilayer solvent reaction. Sodium has been chosen as a representative of a class of highly reactive and readily soluble species, and methanol as a surfactant.
DOES FORMALIN-FIXATION ALTER THE EXTENT OF COLLAGEN AND ELASTIN CROSSLINKS IN HUMAN SPINAL INTERVERTEBRAL DISCS AND LIGAMENTUM FLAVA?
Authors: Tan Celia I. C. , Dunn Sonia , Kent G. Neil , Randall Andrew G. , Edmondston Stephen J. , Singer Kevin P. 
Published: October 2002

The effect of formalin-fixation on the extent of collagen and elastin crosslinks in the matrix of human spinal intervertebral discs and ligamentum flava tissues was evaluated. Fresh discs (n = 5) and ligamentum flava (n = 22) were harvested and separated into two samples. One sample was stored in 10% buffered formalin and the other control sample in a freezer at -20°C. Using HPLC the paired anular (n = 72), nuclear (n = 22) and liagmentum flavum (n = 58) samples were dried, hydrolyzed and assayed for collagen and elastin crosslinks over a 25-week period. There were no significant differences in the collagen, isodesmosine and desmosine content, and the extent of pyridinoline and deoxypyridinoline crosslinks, between fresh and formalin-fixed disc and ligament samples after 25 weeks of formalin fixation. Short-term formalin-fixation does not significantly influence the collagen and elastin crosslink content or the extent of insoluble collagen crosslinks in spinal disc and ligamentum flavum tissues.
MECHANICAL PROPERTIES OF DISEASED HEARTS DURING ADAPTATION
Authors: CHAUDHRY HANS R. , BUKIET BRUCE , RITTER ARTHUR B. , ARORA ROHIT 
Published: October 2002

In this paper, a method is developed to determine the material constants of normal and diseased human hearts in vivo. With these material constants, one can compute regional stresses and strains through the left ventricular (LV) wall. This knowledge provides a better understanding of the heart adaptation process and may lead to earlier diagnosis of heart disease. It also may enable earlier treatment of heart disease, and evaluation of the efficacy of treatments for it. The heart is modeled as a thick cylindrical shell and large deformation theory, incorporating residual stresses is employed to compute the regional stresses and strains through the LV wall. These stresses and strains at the end diastolic state for the normal, hypertensive and congestive heart failure cases are presented. The average circumferential stress is also computed at the end systolic state for these cases.
REACTION RATES: ACCURATE QUANTUM DYNAMICAL CALCULATIONS FOR POLYATOMIC SYSTEMS
Authors: MANTHE UWE 
Published: October 2002

Rate constants of chemical reactions can be computed directly: employing flux correlation functions, no scattering calculations are required. If the reaction is direct, the dynamical simulation can be restricted to the vicinity of the reaction barrier. Therefore accurate thermal rate constants and cumulative reaction probabilities can be calculated for rather large systems. Recent calculations have studied systems with up to six atoms, e.g., H + CH 4 → H 2 + CH 3. The calculations provide a full-dimensional quantum description of the reaction process. In the article, an introduction to the theory of flux correlation functions is given. Methods for the efficient computation of accurate thermal rate constants and cumulative reaction probabilities are reviewed. Connections to transition state ideas are highlighted. The multi-configurational time-dependent Hartree (MCTDH) approach, which facilitates efficient multi-dimensional wave packet propagation, is described and its use in reaction rate calculation is discussed. As examples, recent results for the prototypical polyatomic reaction H + CH 4 → H 2 + CH 3 are presented and rotational effects on the reaction rates of H 2 + OH → H + H 2 O , O + HCl → OH + Cl , and H 2 + Cl → H + HCl are discussed.
Frequency Stabilization of Diode Laser Using External Cavity and Doppler-Free Atomic Spectra
Authors: Utako Tanaka Utako Tanaka , Tsutomu Yabuzaki Tsutomu Yabuzaki 
Published: October 2002

We report on the frequency stabilization of a diode laser, in which the long- and short-term stabilities are simultaneously improved. We use an external cavity whose resonance frequency is locked to the center of a Doppler-free spectrum of the 85Rb-D2 line without direct laser frequency modulation. The obtained linewidth of the diode laser is less than 100 kHz and the long-term stability (trackability) estimated from the variation of the error signal is between 2×10-12 and 2×10-14 at the averaging time τ between 100 ms and 100 s. We also propose a conventional method of stabilization of the magnetic field at the Rb cell used for the frequency stabilization.
Recent Experimental Results on Hydrogen Masers and Time and Frequency Service System at Shanghai Observatory
Authors: Zhai Zao-cheng , Hu Jin-lun , Lin Chuan-Fu , Guan-zong Wang Guan-zong Wang , Su-guang Jian Su-guang Jian 
Published: October 2002

The recent activities and research progress on time and frequency (T/F) at Shanghai Observatory are summarized as follows.
1. Atomic frequency standards The features and performance of the hydrogen masers constructed at Shanghai Observatory, and the research of a primary Cs standard are introduced.
2. Atomic time scale The recent progress on Shanghai Observatory's atomic time scale AT(SO) are described. New devices and a new time-measuring system adopted in AT(SO) are also introduced.
3. Satellite T/F transfer Experiments and preliminary results in time synchronization via Chinese communication satellite are discussed.
4. Time service and T/F applications T/F applications in Shanghai Observatory's several research projects such as the very long baseline interferometer (VLBI) system and satellite laser ranging system are described.
Continuous Wave GaInAsP/InP Surface Emitting Lasers with a Thermally Conductive MgO/Si Mirror
Authors: Toshihiko Baba Toshihiko Baba , Yukiaki Yogo Yukiaki Yogo , Katsumasa Suzuki Katsumasa Suzuki , Fumio Koyama Fumio Koyama , Kenichi Iga Kenichi Iga 
Published: October 2002

We have fabricated continuous wave (cw) GaInAsP/InP vertical-cavity surface emitting lasers. For effective carrier confinement, we employed a planar buried heterostructure grown by a single-step maskless regrowth process. In addition, we introduced a novel multilayer mirror consisting of magnesia (MgO) and silicon (Si), which provides high reflectivity and high thermal conductivity simultaneously. Both threshold reduction and improvement of the highest cw temperature were clearly demonstrated by this new mirror; the highest cw temperature of 14° C was achieved with the threshold current of 22 mA. From the comparison of threshold current between cw and pulsed conditions, the increase of device temperature by the cw injection was estimated to be 8–15 K.
The Radical Transport in the Narrow-Gap-Reactive-Ion Etcher in SF6by the Relaxation Continuum Model
Authors: Nobuhiko Nakano Nobuhiko Nakano , Zoran Lj. Petrović  Zoran Lj. Petrović  , Toshiaki Makabe Toshiaki Makabe 
Published: October 2002

We have established a selfconsistent modeling of a narrow-gap reactive ion etcher (N-gap-RIE) with parallel-plate geometry in SF6. Using the discharge structure of the relaxation continuum model, we have numerically predicted the radical transport to the surface of N-gap-RIE in SF6under two different surface reactions. The spatiotemporal profiles of radicals and neutrals are demonstrated for a long time scale (0–1 s) at between 0.05 Torr and 1.0 Torr at 13.56 MHz. The estimated etch rate of Si wafer with F radicals agrees reasonably well with the previous experimental value obtained under a low-power condition. It is stressed from the present result that the ion-molecule reactions for the generation of F radicals as well as the electron impact dissociation of SF6are of great importance.