1,293 research outputs found
Extended Feynman Formula for the Harmonic Oscillator by the Discrete Time Method
We calculate the Feynman formula for the harmonic oscillator beyond and at
caustics by the discrete formulation of path integral. The extension has been
made by some authors, however, it is not obtained by the method which we
consider the most reliable regularization of path integral. It is shown that
this method leads to the result with, especially at caustics, more rigorous
derivation than previous.Comment: 9 page
Universal charge transport of the Mn oxides in the high temperature limit
We have found that various Mn oxides have the universal resistivity and
thermopower in the high temperature limit. The resistivities and thermopowers
of all the samples go toward constant values of 71 mcm and
3 V/K, which are independent of carrier density and crystal
structures. We propose that the electric conduction occurs in a highly
localized way in the high temperature limit, where the exchange of entropy and
charge occurs in the neighboring Mn and Mn ions.Comment: 4 pages, 4 eps figures, to be published in J. Appl. Phy
Thermoelectric properties of the layered Pd oxide R_2PdO_4 (R = La, Nd, Sm and Gd)
We prepared polycrystalline samples of RPdO (R = La, Nd, Sm and Gd)
using a NaCl-flux technique. The measured resistivity is of the order of
10 cm at room temperature, which is two orders of magnitude
smaller than the values reported so far. We further studied the substitution
effects of Ce for Nd in NdCePdO, where the substituted Ce
decreases the resistivity and the magnitude of the thermopower. The activation
energy gap of 70-80 meV and the effective mass of 15 evaluated from the
measured data are suitable for thermoelectric materials, but the mobility of
10 cm/Vs is much lower than a typical value of 1-10 cm/Vs for
other thermoelectric oxides.Comment: 5 pages, 5 figures, to appear in J. Phys. Soc. Jp
Trends in the Nontuberculous Mycobacterial Disease Mortality Rate in Japan: A Nationwide Observational Study, 1997–2016
Background. The incidence of nontuberculous mycobacterial (NTM) infections has been increasing worldwide, becoming a significant healthcare burden especially among elderly people. This study aimed to evaluate the trends in NTM-associated mortality in Japan.
Methods. This study used vital statistics data and data on all NTM-associated deaths (N = 18 814) among individuals aged >= 40 years in Japan from 1997 to 2016. We calculated the crude and age-adjusted mortality rates by age and sex and used joinpoint regression to analyze trends and estimate the average annual percentage change (AAPC). We compared crude NTM- and tuberculosis-associated mortality rates by sex.
Results. The overall crude annual mortality rate increased from 0.63/100 000/year in 1997 to 1.93/100 000/year in 2016 and was the highest among individuals aged 80-84 years. The AAPC of the crude mortality rates among men of all ages and women aged 40-59 years were stable but increased among women aged 60-79 years (3.5%; 95% confidence interval [CI ], 2.8-4.3) and >= 80 years (4.3%; 95% CI, 3.7-4.9). Among men, the age-adjusted mortality rates did not show a significant trend, while among women, the rates increased over the study period (AAPC, 4.6%; 95% CI, 2.7-6.6). In women, the crude NTM-associated mortality rate exceeded the tuberculosis mortality rate in 2014, 2015, and 2016.
Conclusions. NTM mortality increased in Japan between 1997 and 2016, especially among the elderly female population. Given the increasing NTM-associated mortality and the susceptible aging population, public health authorities in Japan should pay greater attention to NTM infections
Impurity-induced transition and impurity-enhanced thermopower in the thermoelectric oxide NaCo_{2-x}Cu_x$O_4
Various physical quantities are measured and analysed for the Cu-substituted
thermoelectric oxide NaCo_{2-x}Cu_xO_4. As was previously known, the
substituted Cu enhances the thermoelectric power, while it does not increase
the resistivity significantly. The susceptibility and the electron
specific-heat are substantially decreased with increasing x, which implies that
the substituted Cu decreases the effective-mass enhancement. Through a
quantitative comparison with the heavy fermion compounds and the valence
fluctuation systems, we have found that the Cu substitution effectively
increases the coupling between the conduction electron and the magnetic
fluctuation. The Cu substitution induces a phase transition at 22 K that is
very similar to a spin-density-wave transition.Comment: 8 pages, 7 figures, submitted to Phys. Rev.
High flux polarized gamma rays production: first measurements with a four-mirror cavity at the ATF
The next generation of e+/e- colliders will require a very intense flux of
gamma rays to allow high current polarized positrons to be produced. This can
be achieved by converting polarized high energy photons in polarized pairs into
a target. In that context, an optical system consisting of a laser and a
four-mirror passive Fabry-Perot cavity has recently been installed at the
Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized
gamma rays by inverse Compton scattering. In this contribution, we describe the
experimental system and present preliminary results. An ultra-stable
four-mirror non planar geometry has been implemented to ensure the polarization
of the gamma rays produced. A fiber amplifier is used to inject about 10W in
the high finesse cavity with a gain of 1000. A digital feedback system is used
to keep the cavity at the length required for the optimal power enhancement.
Preliminary measurements show that a flux of about /s with
an average energy of about 24 MeV was generated. Several upgrades currently in
progress are also described
Representations and Properties of Generalized Statistics, Coherent States and Robertson Uncertainty Relations
The generalization of statistics, including bosonic and fermionic
sectors, is performed by means of the so-called Jacobson generators. The
corresponding Fock spaces are constructed. The Bargmann representations are
also considered. For the bosonic statistics, two inequivalent Bargmann
realizations are developed. The first (resp. second) realization induces, in a
natural way, coherent states recognized as Gazeau-Klauder (resp.
Klauder-Perelomov) ones. In the fermionic case, the Bargamnn realization leads
to the Klauder-Perelomov coherent states. For each considered realization, the
inner product of two analytic functions is defined in respect to a measure
explicitly computed. The Jacobson generators are realized as differential
operators. It is shown that the obtained coherent states minimize the
Robertson-Schr\"odinger uncertainty relation.Comment: 16 pages, published in JP
Measurement of parity-nonconserving rotation of neutron spin in the 0.734-eV p-wave resonance of
The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave
resonance of was measured with the neutron transmission method. Two
optically polarized cells were used before and behind a a 5-cm long
target as a polarizer and an analyzer of neutron spin. The rotation
angle was carefully measured by flipping the direction of polarization
in the polarizer in sequence. The peak-to-peak value of the spin rotation was
found to be rad/cm which was consistent with
the previous experiments. But the result was statisticallly improved. The s-p
mixing model gives the weak matrix element as meV. The
value agrees well with the one deduced from the parity-nonconserving
longitudinal asymmetry in the same resonance
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