54 research outputs found
High concordance between mental stress-induced and adenosine-induced myocardial ischemia assessed using SPECT in heart failure patients:Hemodynamic and biomarker correlates
Mental stress can trigger myocardial ischemia, but the prevalence of mental stress–induced ischemia in congestive heart failure (CHF) patients is unknown. We characterized mental stress–induced and adenosine-induced changes in myocardial perfusion and neurohormonal activation in CHF patients with reduced left-ventricular function using SPECT to precisely quantify segment-level myocardial perfusion. Methods: Thirty-four coronary artery disease patients (mean age ± SD, 62 ± 10 y) with CHF longer than 3 mo and ejection fraction less than 40% underwent both adenosine and mental stress myocardial perfusion SPECT on consecutive days. Mental stress consisted of anger recall (anger-provoking speech) followed by subtraction of serial sevens. The presence and extent of myocardial ischemia was quantified using the conventional 17-segment model. Results: Sixty-eight percent of patients had 1 ischemic segment or more during mental stress and 81% during adenosine. On segment-by-segment analysis, perfusion with mental stress and adenosine were highly correlated. No significant differences were found between any 2 time points for B-type natriuretic peptide, tumor necrosis factor-α, IL-1b, troponin, vascular endothelin growth factor, IL-17a, matrix metallopeptidase-9, or C-reactive protein. However, endothelin-1 and IL-6 increased, and IL-10 decreased, between the stressor and 30 min after stress. Left-ventricular end diastolic dimension was 179 ± 65 mL at rest and increased to 217 ± 71 after mental stress and 229 ± 86 after adenosine (P < 0.01 for both). Resting end systolic volume was 129 ± 60 mL at rest and increased to 158 ± 66 after mental stress (P < 0.05) and 171 ± 87 after adenosine (P < 0.07), with no significant differences between adenosine and mental stress. Ejection fraction was 30 ± 12 at baseline, 29 ± 11 with mental stress, and 28 ± 10 with adenosine (P = not significant). Conclusion: There was high concordance between ischemic perfusion defects induced by adenosine and mental stress, suggesting that mental stress is equivalent to pharmacologic stress in eliciting clinically significant myocardial perfusion defects in CHF patients. Cardiac dilatation suggests clinically important changes with both conditions. Psychosocial stressors during daily life may contribute to the ischemic burden of CHF patients with coronary artery disease. Keywords: heart failure, mental stress, ischemia, myocardial perfusion, adenosine, single-photon emission computed tomograph
Graphene: new bridge between condensed matter physics and quantum electrodynamics
Graphene is the first example of truly two-dimensional crystals - it's just
one layer of carbon atoms. It turns out to be a gapless semiconductor with
unique electronic properties resulting from the fact that charge carriers in
graphene demonstrate charge-conjugation symmetry between electrons and holes
and possess an internal degree of freedom similar to ``chirality'' for
ultrarelativistic elementary particles. It provides unexpected bridge between
condensed matter physics and quantum electrodynamics (QED). In particular, the
relativistic Zitterbewegung leads to the minimum conductivity of order of
conductance quantum in the limit of zero doping; the concept of Klein
paradox (tunneling of relativistic particles) provides an essential insight
into electron propagation through potential barriers; vacuum polarization
around charge impurities is essential for understanding of high electron
mobility in graphene; index theorem explains anomalous quantum Hall effect.Comment: misprints are fixed; to appear in special issue of Solid State
Communication
Gauss hypergeometric function: reduction, epsilon-expansion for integer/half-integer parameters and Feynman diagrams
The Gauss hypergeometric functions 2F1 with arbitrary values of parameters
are reduced to two functions with fixed values of parameters, which differ from
the original ones by integers. It is shown that in the case of integer and/or
half-integer values of parameters there are only three types of algebraically
independent Gauss hypergeometric functions. The epsilon-expansion of functions
of one of this type (type F in our classification) demands the introduction of
new functions related to generalizations of elliptic functions. For the five
other types of functions the higher-order epsilon-expansion up to functions of
weight 4 are constructed. The result of the expansion is expressible in terms
of Nielsen polylogarithms only. The reductions and epsilon-expansion of q-loop
off-shell propagator diagrams with one massive line and q massless lines and
q-loop bubble with two-massive lines and q-1 massless lines are considered. The
code (Mathematica/FORM) is available via the www at this URL
http://theor.jinr.ru/~kalmykov/hypergeom/hyper.htmlComment: 19 pages, LaTeX, 1-eps figure; v5: The code (Mathematica/FORM) is
available via the www http://theor.jinr.ru/~kalmykov/hypergeom/hyper.htm
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
On the effect of the near field records on the steel braced frames equipped with energy dissipating devices
Avaliação ecológica rápida da fauna de vespas (Hymenoptera: Aculeata) do Parque Nacional da Serra do Divisor, Acre, Brasil
Causal Relationship between Obesity and Vitamin D Status: Bi-Directional Mendelian Randomization Analysis of Multiple Cohorts
M.-L. Lokki työryhmän Genetic Invest Anthropometric Trai jäsen.Peer reviewe
Correction: “The 5th edition of The World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms” Leukemia. 2022 Jul;36(7):1720–1748
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