2,308 research outputs found
Penetration depth, multiband superconductivity, and absence of muon-induced perturbation in superconducting PrOsSb
Transverse-field muon spin rotation (SR) experiments in the
heavy-fermion superconductor PrOsSb ( K) suggest that
the superconducting penetration depth is temperature-independent
at low temperatures, consistent with a gapped quasiparticle excitation
spectrum. In contrast, radiofrequency (rf) inductive measurements yield a
stronger temperature dependence of , indicative of point nodes in
the gap. This discrepancy appears to be related to the multiband structure of
PrOsSb. Muon Knight shift measurements in PrOsSb
suggest that the perturbing effect of the muon charge on the neighboring
Pr crystalline electric field is negligibly small, and therefore is
unlikely to cause the difference between the SR and rf results.Comment: 10 pages, 7 figure
Detection of Neutron Scattering from Phase IV of Ce0.7La0.3B6: A Confirmation of the Octupole Order
We have performed a single crystal neutron scattering experiment on
Ce0.7La0.3B6 to investigate the order parameter of phase IV microscopically.
Below the phase transition temperature 1.5 K of phase IV, weak but distinct
superlattice reflections at the scattering vector (h/2,h/2,l/2) (h, l = odd
number) have been observed by neutron scattering for the first time. The
intensity of the superlattice reflections is stronger for high scattering
vectors, which is quite different from the usual magnetic form factor of
magnetic dipoles. This result directly evidences that the order parameter of
phase IV has a complex magnetization density, consistent with the recent
experimental and theoretical prediction in which the order parameter is the
magnetic octupoles Tbeta with Gamma5 symmetry of point group Oh. Neutron
scattering experiments using short wavelength neutrons, as done in this study,
could become a general method to study the high-rank multipoles in f electron
systems.Comment: 4 pages, 4 figure
Disorder, inhomogeneity and spin dynamics in f-electron non-Fermi liquid systems
Muon spin rotation and relaxation (SR) experiments have yielded evidence
that structural disorder is an important factor in many f-electron-based
non-Fermi-liquid (NFL) systems. Disorder-driven mechanisms for NFL behaviour
are suggested by the observed broad and strongly temperature-dependent SR
(and NMR) linewidths in several NFL compounds and alloys. Local disorder-driven
theories (Kondo disorder, Griffiths-McCoy singularity) are, however, not
capable of describing the time-field scaling seen in muon spin relaxation
experiments, which suggest cooperative and critical spin fluctuations rather
than a distribution of local fluctuation rates. A strong empirical correlation
is established between electronic disorder and slow spin fluctuations in NFL
materialsComment: 24 pages, 15 figures, submitted to J. Phys.: Condens. Matte
Bowel Preparation for Colonoscopy with Sodium Phosphate Solution versus Polyethylene Glycol-Based Lavage: A Multicenter Trial
Background: Adequate bowel preparation is essential for
accurate colonoscopy. Both oral sodium phosphate (NaP) and
polyethylene glycol-based lavage (PEG-ELS) are used predominantly
as bowel cleansing modalities. NaP has gained popularity due to
low drinking volume and lower costs. The purpose of this
randomized multicenter observer blinded study was to compare
three groups of cleansing (NaP, NaP + sennosides, PEG-ELS +
sennosides) in reference to tolerability, acceptance, and
cleanliness. Patient and Methods: 355 outpatients between 18 and
75 years were randomized into three groups (A, B, C) receiving NaP =
A, NaP, and sennosides = B or PEG-ELS and sennosides = C.
Gastroenterologists performing colonoscopies were blinded to the
type of preparation. All patients documented tolerance and adverse
events. Vital signs, premedication, completeness, discomfort, and
complications were recorded. A quality score (0–4) of cleanliness
was generated. Results: The three groups were similar
with regard to age, sex, BMI, indication for colonoscopy, and
comorbidity. Drinking volumes (L) (A = 4.33 + 1.2, B = 4.56 + 1.18, C = 4.93 + 1.71) were in favor of NaP
(P = .005). Discomfort from
ingested fluid was recorded in A = 39.8% (versus C: P = .015),
B = 46.6% (versus C: P = .147), and C = 54.6%. Differences in tolerability and acceptance between the three groups were
statistically not significant. No differences in adverse events
and the cleanliness effects occurred in the three groups (P = .113).
The cleanliness quality scores 0–2 were calculated in A:
77.7%, B: 86.7%, and C: 85.2%. Conclusions:
These data fail to demonstrate significant differences in
tolerability, acceptance, and preparation quality between the
three types of bowel preparation for colonoscopy. Cleansing with
NaP was not superior to PEG-ELS
Lattice Distortion and Octupole Ordering Model in CexLa1-xB6
Possible order parameters of the phase IV in CexLa1-xB6 are discussed with
special attention to the lattice distortion recently observed. A
\Gamma_{5u}-type octupole order with finite wave number is proposed as the
origin of the distortion along the [111] direction. The \Gamma_8 crystalline
electric field (CEF) level splits into three levels by a mean field with the
\Gamma_{5u} symmetry. The ground and highest singlets have the same quadrupole
moment, while the intermediate doublet has an opposite sign. It is shown that
any collinear order of \Gamma_{5u}-type octupole moment accompanies the
\Gamma_{5g}-type ferro-quadrupole order, and the coupling of the quadrupole
moment with the lattice induces the distortion. The cusp in the magnetization
at the phase transition is reproduced, but the internal magnetic field due to
the octupole moment is smaller than the observed one by an order of magnitude.Comment: 5 pages, 4 figures, submitted to J. Phys. Soc. Jp
Improved theory of laser-enhanced ionization in flames: comparison with experiment
An improved theory for laser enhanced ionization in flames has been developed for one‐ and two‐step laser excitations. The model gives an analytical expression for the sensitivity of the method for a given transition of any element. The theoretical expression is compared with experimentally measured signals for a number of elements and the agreement is found to be generally good
Prevalence of obstructive sleep apnoea in REM behaviour disorder:response to continuous positive airway pressure therapy
Muon Spin Relaxation Study of (La, Ca)MnO3
We report predominantly zero field muon spin relaxation measurements in a
series of Ca-doped LaMnO_3 compounds which includes the colossal
magnetoresistive manganites. Our principal result is a systematic study of the
spin-lattice relaxation rates 1/T_1 and magnetic order parameters in the series
La_{1-x}Ca_xMnO_3, x = 0.0, 0.06, 0.18, 0.33, 0.67 and 1.0. In LaMnO_3 and
CaMnO_3 we find very narrow critical regions near the Neel temperatures T_N and
temperature independent 1/T_1 values above T_N. From the 1/T_1 in LaMnO_3 we
derive an exchange integral J = 0.83 meV which is consistent with the mean
field expression for T_N. All of the doped manganites except CaMnO_3 display
anomalously slow, spatially inhomogeneous spin-lattice relaxation below their
ordering temperatures. In the ferromagnetic (FM) insulating
La_{0.82}Ca_{0.18}MnO_3 and ferromagnetic conducting La_{0.67}Ca_{0.33}MnO_3
systems we show that there exists a bi-modal distribution of \muSR rates
\lambda_f and \lambda_s associated with relatively 'fast' and 'slow' Mn
fluctuation rates, respectively. A physical picture is hypothesized for these
FM phases in which the fast Mn rates are due to overdamped spin waves
characteristic of a disordered FM, and the slower Mn relaxation rates derive
from distinct, relatively insulating regions in the sample. Finally, likely
muon sites are identified, and evidence for muon diffusion in these materials
is discussed.Comment: 21 pages, 17 figure
muSR linewidth and isotropic pairing in superconducting PrOs4Sb12
Transverse-field muon spin rotation measurements in the vortex-lattice mixed
state of the heavy-fermion (HF) superconductor PrOs4Sb12 yield a temperature
dependence of the penetration depth indicative of an isotropic or nearly
isotropic energy gap. This is not seen to date in any other HF superconductor
and is a signature of isotropic pairing symmetry, possibly related to a novel
nonmagnetic "quadrupolar Kondo" HF mechanism in PrOs4Sb12. The T = 0 relaxation
rate \sigma_s(0) = 0.91(1) \mu s^-1 yields an estimated penetration depth
\lambda(0) = 3440(20) \AA, which is considerably shorter than in other HF
superconductors.Comment: 4 pages, 5 figure
Few smooth d-polytopes with n lattice points
We prove that, for fixed n there exist only finitely many embeddings of
Q-factorial toric varieties X into P^n that are induced by a complete linear
system. The proof is based on a combinatorial result that for fixed nonnegative
integers d and n, there are only finitely many smooth d-polytopes with n
lattice points. We also enumerate all smooth 3-polytopes with at most 12
lattice points. In fact, it is sufficient to bound the singularities and the
number of lattice points on edges to prove finiteness.Comment: 20+2 pages; major revision: new author, new structure, new result
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