415 research outputs found
Log-aesthetic Curves as Similarity Geometric Analogue of Euler's Elasticae
In this paper we consider the log-aesthetic curves and their generalization
which are used in CAGD. We consider those curves under similarity geometry and
characterize them as stationary integrable flow on plane curves which is
governed by the Burgers equation. We propose a variational formulation of those
curves whose Euler-Lagrange equation yields the stationary Burgers equation.
Our result suggests that the log-aesthetic curves and their generalization can
be regarded as the similarity geometric analogue of Euler's elasticae
Explicit solutions to the semi-discrete modified KdV equation and motion of discrete plane curves
We construct explicit solutions to continuous motion of discrete plane curves
described by a semi-discrete potential modified KdV equation. Explicit formulas
in terms the function are presented. B\"acklund transformations of the
discrete curves are also discussed. We finally consider the continuous limit of
discrete motion of discrete plane curves described by the discrete potential
modified KdV equation to motion of smooth plane curves characterized by the
potential modified KdV equation
Hamiltonian flows on null curves
The local motion of a null curve in Minkowski 3-space induces an evolution
equation for its Lorentz invariant curvature. Special motions are constructed
whose induced evolution equations are the members of the KdV hierarchy. The
null curves which move under the KdV flow without changing shape are proven to
be the trajectories of a certain particle model on null curves described by a
Lagrangian linear in the curvature. In addition, it is shown that the curvature
of a null curve which evolves by similarities can be computed in terms of the
solutions of the second Painlev\'e equation.Comment: 14 pages, v2: final version; minor changes in the expositio
Discrete Integrable Systems and Hodograph Transformations Arising from Motions of Discrete Plane Curves
We consider integrable discretizations of some soliton equations associated
with the motions of plane curves: the Wadati-Konno-Ichikawa elastic beam
equation, the complex Dym equation, and the short pulse equation. They are
related to the modified KdV or the sine-Gordon equations by the hodograph
transformations. Based on the observation that the hodograph transformations
are regarded as the Euler-Lagrange transformations of the curve motions, we
construct the discrete analogues of the hodograph transformations, which yield
integrable discretizations of those soliton equations.Comment: 19 page
Timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space
It is shown that timelike surfaces of constant mean curvature 1 in anti-de
Sitter 3-space can be constructed from a pair of Lorentz holomorphic and
Lorentz antiholomorphic null curves in PSL(2,R) via Bryant type representation
formulae. These formulae are used to investigate an explicit one-to-one
correspondence, the so-called Lawson correspondence, between timelike surfaces
of constant mean curvature 1 in anti-de Sitter 3-space and timelike minimal
surfaces in Minkowski 3-space. The hyperbolic Gauss map of timelike surfaces in
anti-de Sitter 3-space, which is a close analogue of the classical Gauss map is
considered. It is discussed that the hyperbolic Gauss map plays an important
role in the study of timelike surfaces of constant mean curvature 1 in anti-de
Sitter 3-space. In particular, the relationship between the Lorentz
holomorphicity of the hyperbolic Gauss map and timelike surfaces of constant
mean curvature 1 in anti-de Sitter 3-space is studied.Comment: 47 pages, 24 figures, references revised, Annals of Global Analysis
and Geometr
High incidence of silent myocardial ischemia in elderly patients with non insulin-dependent diabetes mellitus
Celem badania była ocena częstości występowania
niemego niedokrwienia mięśnia sercowego u bezobjawowych
chorych na cukrzycę w podeszłym wieku
(> 60 lat). Wstępnym etapem badania była maksymalna
próba wysiłkowa na bieżni ruchomej. Spośród
140 chorych u 54 (38,6%) nie udało się osiągnąć
diagnostycznego poziomu wysiłku podczas
próby lub nie można jej było wykonać z innych przyczyn,
u 39 z 86 chorych (45,3%) uzyskano pozytywny
wynik próby wysiłkowej. W drugim etapie tej pracy
u 93 chorych z dodatnią próbą wysiłkową, ale
u których nie można było uzyskać maksymalnego
wysiłku, wykonano scyntygrafię z użyciem talu w
teście z dipirydamolem. U 39 z 93 chorych (41,9%),
u których wystąpiły zaburzenia perfuzji, rozpoznano
nieme niedokrwienie mięśnia sercowego. U 18
chorych z niemym niedokrwieniem mięśnia sercowego,
którzy wyrazili zgodę, wykonano koronarografię.
U 17 spośród 18 chorych (94,4%) stwierdzono
znacznego stopnia zwężenia naczyń wieńcowych,
co potwierdziło duże znaczenie predykcyjne tej metody.
Podsumowując, stwierdzono, że częstość niemego niemego
niedokrwienia mięśnia sercowego u chorych
na cukrzycę typu 2 w podeszłym wieku jest bardzo
wysoka (26,3%). Te wyniki sugerują, że wczesna
intensywna diagnostyka zmian w naczyniach wieńcowych
może się okazać niezbędna jako uzupełnienie
rutynowego postępowania w tej grupie chorych.The present study was designed reveal the incidence
of silent myocardial ischemia in asymptomatic
elderly non-insulin-dependent diabetic (NIDDM) patients
(aged over 60 years). As a first step screening,
maximal treadmill exercise test was performed. Of
140 patients studied, 54 (38.6%) were unable or not
expected to achieve diagnostic levels of exercise
during treadmill testing. A positive exercise test was
noted in 39 of 86 (45.3%) subjects. As a second step
examination, dipyridamole thallium scintigraphy
was performed for 93 subjects who exhibited a positive
exercise test and could not perform a maximal
exercise test. Abnormal perfusion pattern was
found in 39 of 93 (41.9%), who were finally considered to have a silent myocardial ischemia. Coronary
angiography was performed in 18 subjects with
diagnosis of silent myocardial ischemia, who gave
their consent. Significant coronary artery stenosis
was in fact found in 17 of 18 (94.4%) subjects studied,
confirming a very high positive predictive value
of this diagnostic procedure. In conclusion, elderly
NIDDM patients (aged over 60 years) had an
extremely high prevalence (estimated 26.3%) of silent
myocardial ischemia. This evidence suggests that
early and intensive detection may be needed as
a part of routine care for this grou
Explicit prognostic disclosure to Asian women with breast cancer: A randomized scripted video-vignette study
Health and self-regulatio
The relationship between trust in mass media and the healthcare system and individual health: evidence from the AsiaBarometer Survey
<p>Abstract</p> <p>Background</p> <p>Vertical and horizontal trust, as dimensions of social capital, may be important determinants of health. As mass media campaigns have been used extensively to promote healthy lifestyles and convey health-related information, high levels of individual trust in the media may facilitate the success of such campaigns and, hence, have a positive influence on health. However, few studies have investigated the relationship between trust levels in mass media, an aspect of vertical trust, and health.</p> <p>Methods</p> <p>Based on cross-sectional data of the general population from the AsiaBarometer Survey (2003–2006), we analyzed the relationship between self-rated health and trust in mass media, using a multilevel logistic model, adjusted for age, gender, marital status, income, education, occupation, horizontal trust, and trust in the healthcare system.</p> <p>Results</p> <p>In a total of 39082 participants (mean age 38; 49% male), 26808 (69%) were classified as in good health. By the levels of trust in mass media, there were 6399 (16%) who reported that they trust a lot, 16327 (42%) reporting trust to a degree, 9838 (25%) who do not really trust, 3307 (9%) who do not trust at all, and 191 (0.5%) who have not thought about it. In the multilevel model, trust in mass media was associated with good health (do not trust at all as the base group): the odds ratios (OR) of 1.16 (95% confidence interval (CI) = 1.05–1.27) for do not really trust; OR of 1.35 (95% CI = 1.23–1.49) for trust to a degree, and 1.57 (95% CI = 1.36–1.81) for trust a lot. Horizontal trust and trust in the healthcare system were also associated with health.</p> <p>Conclusion</p> <p>Vertical trust in mass media is associated with better health in Asian people. Since mass media is likely an important arena for public health, media trust should be enhanced to make people healthier.</p
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