26,629 research outputs found
Compression and R-wave detection of ECG/VCG data
Application of information theory to eliminate redundant part of electrocardiogram or vectorcardiogram is described. Operation of medical equipment to obtain three dimensional study of patient is discussed. Use of fast Fourier transform to accomplish data compression is explained
Lower critical field measurements in YBa2Cu3O(6+x) single crystals
The temperature dependence of the lower critical field in YBa2Cu3O(6+x) single crystals was determined by magnetization measurements with the applied field parallel and perpendicular to the c-axis. Results are compared with data from the literature and fitted to Ginzberg-Landau equations by assuming a linear dependence of the parameter kappa on temperature. A value of 7 plus or minus 2 kOe was estimated for the thermodynamic critical field at T = O by comparison of calculated H (sub c2) values with experimental data from the literature
Measurement of H(sub c1) in a single crystal of YBa2Cu3O7 with low pinning
The measurement of H(sub c1) in barium yttrium copper oxide (BYCO) is often ambiguous because the presence of large pinning forces makes it difficult to discern exactly where the first deviation from linearity occurs. In addition there are complications because demagnetizing factors are often not well known. By utilizing a single crystal of YBCO with a nearly cubic shape, the uncertainty in the demagnetizing factor was minimized. In addition, the crystal used exhibited a very small amount of pinning with H applied perpendicular to the c axis, and a sharp break in the initial magnetization vs. field curve could be observed over a wide range of temperature. This allowed a precise determination of H(sub c1). The measured values of H(sub c1) could be well described by the Abrikosov relation with a Ginzburg-Landau parameter which varied linearly with temperature
Quantum computers can search arbitrarily large databases by a single query
This paper shows that a quantum mechanical algorithm that can query
information relating to multiple items of the database, can search a database
in a single query (a query is defined as any question to the database to which
the database has to return a (YES/NO) answer). A classical algorithm will be
limited to the information theoretic bound of at least O(log N) queries (which
it would achieve by using a binary search).Comment: Several enhancements to the original pape
A comparative analysis of the decoupling effects in a magnetic forming beryllium coil assembly
Digital computer for determining currents and forces in magnetic forming beryllium coil assembl
Helicoidal surfaces with constant anisotropic mean curvature
We study surfaces with constant anisotropic mean curvature which are
invariant under a helicoidal motion. For functionals with axially symmetric
Wulff shapes, we generalize the recently developed twizzler representation of
Perdomo to the anisotropic case and show how all helicoidal constant
anisotropic mean curvature surfaces can be obtained by quadratures
Fluctuations of Quantum Entanglement
It is emphasized that quantum entanglement determined in terms of the von
Neumann entropy operator is a stochastic quantity and, therefore, can
fluctuate. The rms fluctuations of the entanglement entropy of two-qubit
systems in both pure and mixed states have been obtained. It has been found
that entanglement fluctuations in the maximally entangled states are absent.
Regions where the entanglement fluctuations are larger than the entanglement
itself (strong fluctuation regions) have been revealed. It has been found that
the magnitude of the relative entanglement fluctuations is divergent at the
points of the transition of systems from an entangled state to a separable
state. It has been shown that entanglement fluctuations vanish in the separable
states.Comment: 5 pages, 4 figure
Motion of the Zinc Ions in Catalysis by a Dizinc Metallo-β-Lactamase
We report rapid-freeze-quench X-ray absorption spectroscopy of a dizinc metallo-β-lactamase (MβL) reaction intermediate. The Zn(II) ions in the dinuclear active site of the S. maltophilia Class B3 MβL move away from each other, by ∼0.3 Å after 10 ms of reaction with nitrocefin, from 3.4 to 3.7 Å. Together with our previous characterization of the resting enzyme and its nitrocefin product complex, where the Zn(II) ion separation relaxes to 3.6 Å, these data indicate a scissoring motion of the active site that accompanies the ring-opening step. The average Zn(II) coordination number of 4.5 in the resting enzyme appears to be maintained throughout the reaction with nitrocefin. This is the first direct structural information available on early stage dizinc metallo-β-lactamase catalysis
- …