Excitation spectrum of PrOs(4)Sb(12) under a magnetic field.

The evolution of the magnetic excitation spectrum of the heavy fermion superconductor PrOs(4)Sb(12) was studied by inelastic neutron scattering on crossing the critical field H(c2) for superconductivity at low temperature. The peak positions in energy and the peak intensities of the modes of the triplet split by magnetic field confirm the known crystal field parameters for PrOs(4)Sb(12) in T(h) symmetry. A selective broadening of the lineshape occurs on increasing the magnetic field: the linewidth of the upper mode of the triplet increases while the one of the middle mode does not.

Longitudinal spin density wave order in a quasi-1D Ising-like quantum antiferromagnet.

From neutron diffraction measurements on a quasi-1D Ising-like Co2+ spin compound BaCo2V2O8, we observed an appearance of a novel type of incommensurate ordering in magnetic fields. This ordering is essentially different from the Néel-type ordering, which is expected for the classical system, and the peculiar spin structure is caused by quantum fluctuation inherent in the quantum spin chain. A Tomonaga-Luttinger liquid nature characteristic of the gapless quantum 1D system is responsible for the realization of the incommensurate ordering.

Genetic risk for myocardial infarction determined by polymorphisms of candidate genes in a Japanese population.

BACKGROUND: Although several environmental factors influence the development of myocardial infarction (MI), genetic factors have been shown to contribute to individual susceptibility to this condition. OBJECTIVE: To identify gene polymorphisms that confer susceptibility to MI in order to allow assessment of genetic risk for this condition. METHODS: 3433 unrelated Japanese people (1931 men, 1502 women) were entered into the study. These comprised 1328 subjects with MI (1036 men, 292 women) and 2105 controls (895 men, 1210 women). The genotypes for 40 polymorphisms of 31 candidate genes were determined with a method that combines PCR and sequence-specific oligonucleotide probes with suspension array technology. RESULTS: The chi(2) test revealed that six polymorphisms were significantly (false discovery rate <0.05) related to the prevalence of MI. Further examination by multivariable logistic regression analysis with adjustment for age, sex, body mass index and the prevalence of hypertension, diabetes mellitus and hypercholesterolaemia, in addition to a stepwise forward selection procedure found that the A-->C (Gln1334His) polymorphism (rs3742207) of the collagen type IV alpha-1 gene (COL4A1) and the A-->G polymorphism (rs4804611) of the zinc finger protein 627 gene (ZNF627) were significantly (p<0.05) associated with the prevalence of MI. The variant C allele of COL4A1 was protective against MI, whereas the variant G allele of ZNF627 represented a risk factor for this condition. CONCLUSIONS: Determination of genotypes for COL4A1 and ZNF627 may prove informative for assessment of the genetic risk for MI.

Genetic risk for metabolic syndrome: examination of candidate gene polymorphisms related to lipid metabolism in Japanese people.

BACKGROUND: The aetiology of metabolic syndrome is complex, being determined by the interplay of both genetic and environmental factors. The aim of this study was to identify genetic polymorphisms that confer susceptibility to metabolic syndrome, to allow prediction of genetic risk for this condition. METHODS: The study population comprised 2417 unrelated Japanese subjects (1522 with metabolic syndrome and 895 controls). The genotypes for 44 polymorphisms of 31 candidate genes related to lipid metabolism were determined using a combination of PCR and sequence-specific oligonucleotide probes with suspension array technology. RESULTS: The chi(2) test and subsequent multivariate logistic regression analysis with adjustment for age, sex and smoking status found that the-3A-->G and 553G-->T (Gly185Cys) polymorphisms of APOA5, the 2052T-->C (Val653Val) and 1866C-->T (Asn591Asn) polymorphisms of LDLR, the 13989A-->G (Ile118Val) polymorphism of CYP3A4 and the 1014T-->A polymorphism of C1QTNF5 were significantly (false discovery rate <0.05) associated with the prevalence of metabolic syndrome, with the variant alleles of APOA5 and C1QTNF5 representing risk factors for and those of LDLR and CYP3A4 being protective against this condition. Serum levels of triglycerides and high-density lipoprotein (HDL) cholesterol differed significantly (p<0.05) among APOA5 genotypes; the serum level of HDL cholesterol differed among LDLR genotypes; and the fasting plasma glucose level and body mass index differed between CYP3A4 and C1QTNF5 genotypes, respectively. CONCLUSIONS: APOA5, LDLR, CYP3A4 and C1QTNF5 are susceptibility loci for metabolic syndrome in Japanese people. Genotypes for these polymorphisms may prove informative for prediction of genetic risk for metabolic syndrome.

Probing the coulomb interaction of the unconventional superconductor by phonon spectroscopy.

The phonon dispersion curves of the superconductor PuCoGa(5) were studied by inelastic x-ray scattering at room temperature. The experimental data agree well with ab initio lattice dynamics calculations. An accurate description of the phonon spectrum is obtained only when a local Coulomb repulsion U approximately equal 3 eV among 5f electrons is taken into account.

Magnetization dynamics in the normal and superconducting phases of UPd(2)Al(3): II. Inferences on the nodal gap symmetry.

This paper provides an analysis of neutron inelastic scattering experiments on single crystals of UPd(2)Al(3). The emphasis is on establishing robust general inferences on the joint antiferromagnetic-superconducting state that characterizes UPd(2)Al(3) at low temperatures. A distinction is drawn between these conclusions and various theoretical perspectives of a more model-sensitive nature that have been raised in the literature.

Direct observation of quadrupolar excitons in the heavy-fermion superconductor PrOs4Sb12.

We report inelastic neutron scattering experiments performed to investigate the low energy magnetic excitations on single crystals of the heavy-fermion superconductor PrOs(4)Sb(12). The observed excitation clearly softens at a wave vector Q=(1,0,0), which is the same as the modulation vector of the field-induced antiferro-quadrupolar ordering, and its intensity at Q=(1,0,0) is smaller than that around the zone center. This result directly evidences that this excitonic behavior is derived mainly from nonmagnetic quadrupolar interactions. Furthermore, the narrowing of the linewidths of the excitations below the superconducting transition temperature indicates the close connection between the superconductivity and the excitons.

Spin excitations in an anisotropic bond-alternating quantum s = 1 chain in a magnetic field: contrast to haldane spin chains.

Inelastic neutron scattering experiments on the S = 1 quasi-one-dimensional bond-alternating antiferromagnet Ni(C9D24N4)(NO2)ClO4 have been performed under magnetic fields below and above a critical field Hc at which the energy gap closes. Normal field dependence of Zeeman splitting of the excited triplet modes below Hc has been observed, but the highest mode is unusually small and smears out with increasing field. This can be explained by an interaction with a low-lying two magnon continuum at q(parallel) = pi that is present in dimerized chains but absent in uniform ones. Above Hc, we find only one excited mode, in stark contrast with three massive excitations previously observed in the structurally similar Haldane-gap material NDMAP [A. Zheludev, Phys. Rev. B 68, 134438 (2003)].

Efficacy of methylprednisolone pulse therapy on neuroleptic malignant syndrome in Parkinson's disease.

BACKGROUND: Neuroleptic malignant syndrome (NMS) is a dangerous complication in patients with Parkinson's disease (PD). AIMS: To evaluate the efficacy of methylprednisolone pulse therapy compared to placebo in PD patients with NMS. METHODS: In a double blind, placebo controlled study, 20 PD patients with NMS received steroid pulse therapy for three days, and 20 PD patients received placebo. Both groups received levodopa, bromocriptine, and dantrolene. RESULTS: NMS in the steroid group healed within 10 days in 17 patients; median value of duration of illness of NMS in this group was 7 days (range 4-20). NMS in the placebo group healed within 10 days in five patients; in the remaining 15, it persisted for 12-27 days after the onset of NMS; median value of duration illness of NMS in this group was 18 days. Hyperthermia, rigidity, and consciousness improved within 10 days in many patients in the steroid group; these signs persisted more than 10 days in many patients in the placebo group. CONCLUSIONS: Steroid pulse therapy is useful in NMS for reducing the illness duration and improving symptoms.

Does compensatory hyperparathyroidism predispose to ischemic stroke?

BACKGROUND: Parathyroid hormone (PTH) is vasoactive, and the endothelium is one of the target tissues of this hormone. Hyperparathyroidism is frequently associated with hypertension. OBJECTIVE: To determine if hyperparathyroidism, which develops particularly in elderly women as a compensatory mechanism to osteoporosis, may be a risk factor for ischemic stroke. METHODS: Serum PTH levels and bone mineral density (BMD) in 107 elderly patients with ischemic stroke (>or=65 years old) were assessed on the day of onset. The control group consisted of 107 healthy volunteers matched for age and sex. RESULTS: BMD was significantly lower and serum PTH higher in female stroke patients than in control subjects; there was a negative correlation between these two measurements. One-third of the female stroke patients had a serum PTH level higher than the mean + 2 SD of the control subjects (high PTH group), and the interval between menopause and the stroke was significantly longer in the high PTH group than in the normal PTH group. Multiple logistic analyses revealed hypertension and ischemic heart disease were more prevalent in the high PTH group. BMD and PTH were normal in male stroke patients. CONCLUSION: High serum PTH level may be associated with high incidence of ischemic stroke in women, possibly through the increased incidence of hypertension.

Magnetic structure, phase diagram, and a new type of spin-flop transition dominated by higher order interaction in a localized 5f system U3Pd20Si6.

The magnetic structure of the localized-5f uranium intermetallic compound U3Pd20Si6 has been determined by means of a neutron diffraction experiment. Our data demonstrate that this compound has a collinear coupling of the sublattice ordering of the uranium spins on the 4a and 8c sites. We conclude that higher-order exchange and/or quadrupole interactions are necessary to stabilize this unique collinear structure. We discovered a new type of spin-flop transition against the uniaxial anisotropy induced by this collinear coupling.