1,803 research outputs found
In--Flight () Reactions for the Formation of Kaonic Atoms and Kaonic Nuclei in Green function method
We study theoretically the kaonic atom and kaonic nucleus formations in the
in--flight () reactions using the Green function method, which is suited
to evaluate formation rates both of stable and unstable bound systems. We
consider C and O as the targets and calculate the spectra of the
() reactions. We conclude that a no peak structure due to kaonic nucleus
formation is expected in the reaction spectra calculated with the chiral
unitary kaon--nucleus optical potential. In the spectra with the
phenomenological deep kaon--nucleus potential, we may have possibilities to
observe some structures due to kaonic nucleus states. For all cases, we have
peaks due to the kaonic atom formations in the reaction spectra.Comment: 10 pages, 9 figures, newly calculated results added, revisions and
updated references, to appear in Physical Review
Intrabeam Scattering Analysis of ATF Beam Measurements
At the Accelerator Test Facility (ATF) at KEK intrabeam scattering (IBS) is a
strong effect for an electron machine. It is an effect that couples all
dimensions of the beam, and in April 2000, over a short period of time, all
dimensions were measured as functions of current. In this report we derive a
simple relation for the growth rates of emittances due to IBS. We apply the
theories of Bjorken-Mtingwa, Piwinski, and a formula due to Raubenheimer to the
ATF parameters, and find that the results all agree (if in Piwinski's formalism
we replace the dispersion squared over beta by the dispersion invariant).
Finally, we compare theory, including the effect of potential well bunch
lengthening, with the April 2000 measurements, and find reasonably good
agreement in the energy spread and horizontal emittance dependence on current.
The vertical emittance measurement, however, implies that either: there is
error in the measurement (equivalent to an introduction of 0.6% x-y coupling
error), or the effect of intrabeam scattering is stronger than predicted (35%
stronger in growth rates).Comment: 4 pages, 3 figures, Presented at IEEE Particle Accelerator Conferenc
Formation of Deeply Bound Kaonic Atoms in (K^-,N) Reactions
We study theoretically the (K^-,N) reactions for the formation of the deeply
bound kaonic atoms, which were predicted to be quasi--stable with narrow
widths, using the Green function method. We consider various cases with
different target nuclei and energies systematically and find the clear signals
in the theoretical spectra for all cases considered in this article. The
signals show very interesting structures, such as the instead
of the resonance peak. We discuss the origins of the interesting structures and
possibilities to get new information on the existence of the kaonic nuclei from
the spectra of the atomic state formations.Comment: 11 pages, 9 figure
From time-series to complex networks: Application to the cerebrovascular flow patterns in atrial fibrillation
A network-based approach is presented to investigate the cerebrovascular flow
patterns during atrial fibrillation (AF) with respect to normal sinus rhythm
(NSR). AF, the most common cardiac arrhythmia with faster and irregular
beating, has been recently and independently associated with the increased risk
of dementia. However, the underlying hemodynamic mechanisms relating the two
pathologies remain mainly undetermined so far; thus the contribution of
modeling and refined statistical tools is valuable. Pressure and flow rate
temporal series in NSR and AF are here evaluated along representative cerebral
sites (from carotid arteries to capillary brain circulation), exploiting
reliable artificially built signals recently obtained from an in silico
approach. The complex network analysis evidences, in a synthetic and original
way, a dramatic signal variation towards the distal/capillary cerebral regions
during AF, which has no counterpart in NSR conditions. At the large artery
level, networks obtained from both AF and NSR hemodynamic signals exhibit
elongated and chained features, which are typical of pseudo-periodic series.
These aspects are almost completely lost towards the microcirculation during
AF, where the networks are topologically more circular and present random-like
characteristics. As a consequence, all the physiological phenomena at
microcerebral level ruled by periodicity - such as regular perfusion, mean
pressure per beat, and average nutrient supply at cellular level - can be
strongly compromised, since the AF hemodynamic signals assume irregular
behaviour and random-like features. Through a powerful approach which is
complementary to the classical statistical tools, the present findings further
strengthen the potential link between AF hemodynamic and cognitive decline.Comment: 12 pages, 10 figure
Systematic study of the decay rates of antiprotonic helium states
A systematic study of the decay rates of antiprotonic helium (\pbhef and
\pbhet) at CERN AD (Antiproton Decelerator) has been made by a laser
spectroscopic method. The decay rates of some of its short-lived states, namely
those for which the Auger rates are much larger than
their radiative decay rates ( s),
were determined from the time distributions of the antiproton annihilation
signals induced by laser beams, and the widths of the atomic resonance lines.
The magnitude of the decay rates, especially their relation with the transition
multipolarity, is discussed and compared with theoretical calculations.Comment: 6 pages, 5 figures, and 1 tabl
Assessment of pulse rate variability by the method of pulse frequency demodulation
BACKGROUND: Due to its easy applicability, pulse wave has been proposed as a surrogate of electrocardiogram (ECG) for the analysis of heart rate variability (HRV). However, its smoother waveform precludes accurate measurement of pulse-to-pulse interval by fiducial-point algorithms. Here we report a pulse frequency demodulation (PFDM) technique as a method for extracting instantaneous pulse rate function directly from pulse wave signal and its usefulness for assessing pulse rate variability (PRV). METHODS: Simulated pulse wave signals with known pulse interval functions and actual pulse wave signals obtained from 30 subjects with a trans-dermal pulse wave device were analyzed by PFDM. The results were compared with heart rate and HRV assessed from simultaneously recorded ECG. RESULTS: Analysis of simulated data revealed that the PFDM faithfully demodulates source interval function with preserving the frequency characteristics of the function, even when the intervals fluctuate rapidly over a wide range and when the signals include fluctuations in pulse height and baseline. Analysis of actual data revealed that individual means of low and high frequency components of PRV showed good agreement with those of HRV (intraclass correlation coefficient, 0.997 and 0.981, respectively). CONCLUSION: The PFDM of pulse wave signal provides a reliable assessment of PRV. Given the popularity of pulse wave equipments, PFDM may open new ways to the studies of long-term assessment of cardiovascular variability and dynamics
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