Nonreciprocal Phonon Propagation in a Metallic Chiral Magnet

The phonon magnetochiral effect (MChE) is the nonreciprocal acoustic and thermal transports of phonons caused by the simultaneous breaking of the mirror and time-reversal symmetries. So far, the phonon MChE has been observed only in a ferrimagnetic insulator Cu_{2}OSeO_{3}, where the nonreciprocal response disappears above the Curie temperature of 58 K. Here, we study the nonreciprocal acoustic properties of a room-temperature ferromagnet Co_{9}Zn_{9}Mn_{2} for unveiling the phonon MChE close to room temperature. Surprisingly, the nonreciprocity in this metallic compound is enhanced at higher temperatures and observed up to 250 K. This clear contrast between insulating Cu_{2}OSeO_{3} and metallic Co_{9}Zn_{9}Mn_{2} suggests that metallic magnets have a mechanism to enhance the nonreciprocity at higher temperatures. From the ultrasound and microwave-spectroscopy experiments, we conclude that the magnitude of the phonon MChE of Co_{9}Zn_{9}Mn_{2} mostly depends on the Gilbert damping, which increases at low temperatures and hinders the magnon-phonon hybridization. Our results suggest that the phonon nonreciprocity could be further enhanced by engineering the magnon band of materials.

Magnetization-polarization cross-control near room temperature in hexaferrite single crystals

Mutual control of the electricity and magnetism in terms of magnetic (H) and electric (E) fields, the magnetoelectric (ME) effect, offers versatile low power consumption alternatives to current data storage, logic gate, and spintronic devices. Despite its importance, E-field control over magnetization (M) with significant magnitude was observed only at low temperatures. Here we have successfully stabilized a simultaneously ferrimagnetic and ferroelectric phase in a Y-type hexaferrite single crystal up to 450 K, and demonstrated the reversal of large non-volatile M by E field close to room temperature. Manipulation of the magnetic domains by E field is directly visualized at room temperature by using magnetic force microscopy. The present achievement provides an important step towards the application of ME multiferroics.

Mutual control of the electric polarization and magnetization promises for low power consumption spintronic devices but remains challenging. Here the authors show reversal of non-volatile magnetization by electric field as well as the polarization switching by magnetic field in a single-component material, close to room temperature.

Assessment of oral anticoagulation control at pharmacist-managed clinics: A retrospective cohort study

In chronic kidney disease (CKD) patients, the ratio of warfarin enantiomers is changed and becomes unstable due to a reduction of cytochrome P450 (CYP) 2C9 activity of, which contributes to the development of hemorrhagic complications. The aim of this study was to investigate the influence of interventions by clinical pharmacists in addition to guidance by physicians on time in therapeutic range (TTR) control of warfarin therapy for CKD patients with non-valvular atrial fibrillation (NVAF). This retrospective cohort study included NVAF patients with CKD admitted and discharged from a cardiovascular internal medicine ward between March 2011 and July 2013 in Yokosuka Kyousai Hospital. Participants were classified into two groups according to the instructions by clinical pharmacists and physicians (intervention group) and by physicians only (usual care group). The primary outcome was TTR. Secondary outcomes were major bleeding and minor bleeding. In total, 39 participants (28 males, 11 females; mean age: 72.1 years) were classified into the intervention (n = 16) and usual care (n = 23) groups. TTR in the intervention group was significantly higher than in the usual care group. Major bleeding and minor bleeding were not significantly different between the two groups. The intervention of clinical pharmacists with anticoagulation therapy can lead to a proper use of warfarin prescribed by physicians.

The association between the increase in pulse pressure and renal function in chronic kidney disease patients with dyslipidemia

In recent years, an association between chronic kidney disease (CKD) and arteriosclerosis has been identified. Pulse pressure (PP) is used as an index of arteriosclerosis. However, there have been few studies of the relationship between PP and renal dysfunction in patients with CKD. Therefore, we examined the association of increased PP on renal function in patients with CKD and dyslipidemia. This study included 104 patients with CKD who were diagnosed with dyslipidemia and commenced on drug treatment. In the present study, patients with PP ≥65 mmHg were included in the High PP group, and patients with PP <65 mmHg were included in the Low PP group. We compared the High PP group with the Low PP group about background patient characteristics, laboratory data and antihypertensive medications and type. Mutiple logistic regression analysis identified estimated glomerular filtration rate (eGFR) as a significant predictor of PP ≥65 mmHg. In addition, values of BUN, Ccr, and eGFR baseline and 12 months later were compared. In the High PP group, compared with baseline, BUN increased significantly and Ccr and eGFR decreased significantly after 12 months later. We consider that PP may be an auxiliary indicator of generalized arterial sclerosis and renal function.

Electrical magnetochiral effect induced by chiral spin fluctuations

Chirality of matter can produce unique responses in optics, electricity and magnetism. In particular, magnetic crystals transmit their handedness to the magnetism via antisymmetric exchange interaction of relativistic origin, producing helical spin orders as well as their fluctuations. Here we report for a chiral magnet MnSi that chiral spin fluctuations manifest themselves in the electrical magnetochiral effect, i.e. the nonreciprocal and nonlinear response characterized by the electrical resistance depending on inner product of current and magnetic field. Prominent electrical magnetochiral signals emerge at specific temperature-magnetic field-pressure regions: in the paramagnetic phase just above the helical ordering temperature and in the partially-ordered topological spin state at low temperatures and high pressures, where thermal and quantum spin fluctuations are conspicuous in proximity of classical and quantum phase transitions, respectively. The finding of the asymmetric electron scattering by chiral spin fluctuations may explore new electromagnetic functionality in chiral magnets.

The magnetism-induced chirality in electron transportation is of fundamental importantance in condensed matter physics but the origin is still unclear. Here the authors demonstrate that the asymmetric electron scattering by chiral spin fluctuations can be the key to the electrical magnetochiral effect in MnSi.

Robust metastable skyrmions and their triangular-square lattice structural transition in a high-temperature chiral magnet

Skyrmions, topologically protected nanometric spin vortices, are being investigated extensively in various magnets. Among them, many structurally chiral cubic magnets host the triangular-lattice skyrmion crystal (SkX) as the thermodynamic equilibrium state. However, this state exists only in a narrow temperature and magnetic-field region just below the magnetic transition temperature T_c, while a helical or conical magnetic state prevails at lower temperatures. Here we describe that for a room-temperature skyrmion material, β-Mn-type Co ₈Zn ₈Mn ₄, a field-cooling via the equilibrium SkX state can suppress the transition to the helical or conical state, instead realizing robust metastable SkX states that survive over a very wide temperature and magnetic-field region. Furthermore, the lattice form of the metastable SkX is found to undergo reversible transitions between a conventional triangular lattice and a novel square lattice upon varying the temperature and magnetic field. These findings exemplify the topological robustness of the once-created skyrmions, and establish metastable skyrmion phases as a fertile ground for technological applications.

Analysis of factors for poor activated partial thromboplastin time control after dabigatran administration

In this study, we compared patients whose activated partial thromboplastin time (APTT) was prolonged excessively with those whose APTT was controlled within the normal range after dabigatran administration. We analyzed the factors for the APTT prolongation. We divided the patients into two groups: those whose APTTs prolonged to more than 65 s and those whose APTTs were less than 65 s after dabigatran administration. There were 130 patients from March 2011 to July 2013, and we analyzed the background features and laboratory data of these patients. Results showed that there were no significant differences in the patients' background and laboratory data except for the high-density lipoprotein cholesterol (HDL-C) level. However, details of the relationship between the APTT prolongation and the HDL-C level are currently unknown. We hypothesize that the reason for the APTT prolongation is the variability in such parameters as the time of blood drawing, internal time of dabigatran, individual variability, and blood concentration. Therefore, we consider that these parameters need to be carefully evaluated even if APTT does not show prolongation.

Uniaxial stress control of skyrmion phase

Magnetic skyrmions, swirling nanometric spin textures, have been attracting increasing attention by virtue of their potential applications for future memory technology and their emergent electromagnetism. Despite a variety of theoretical proposals oriented towards skyrmion-based electronics (that is, skyrmionics), few experiments have succeeded in creating, deleting and transferring skyrmions, and the manipulation methodologies have thus far remained limited to electric, magnetic and thermal stimuli. Here, we demonstrate a new approach for skyrmion phase control based on a mechanical stress. By continuously scanning uniaxial stress at low temperatures, we can create and annihilate a skyrmion crystal in a prototypical chiral magnet MnSi. The critical stress is merely several tens of MPa, which is easily accessible using the tip of a conventional cantilever. The present results offer a new guideline even for single skyrmion control that requires neither electric nor magnetic biases and consumes extremely little energy.

Chiral magnets can support particle-like magnetization textures called skyrmions which form in lattices and can be manipulated for potential device applications. Here, the authors demonstrate the controlled creation and annihilation of a skyrmion lattice in MnSi single crystals using mechanical stress.

Analysis of factors affecting time in therapeutic range control after warfarin administration

The protective efficacy of warfarin for cardiogenic cerebral embolism has been established. However, warfarin is generally administered to only approximately 35% of the atrial fibrillation patients who required warfarin therapy. It has been reported that international normalized ratio (INR) control was carried out appropriately in < 50% of such patients. Therefore, from the viewpoint of prevention of the onset and recurrence of embolism, the maintenance of a stable anticoagulant level is necessary. In warfarin therapy, in addition to INR control, time in therapeutic range (TTR) also markedly affects the efficacy of warfarin therapy. Therefore, we classified patients into two groups on the basis of the cutoff TTR ≥ 65% at which the inhibitory effect of warfarin on stroke has been observed. We aimed to examine the association between INR and TTR with the correction of the therapeutic efficacy of warfarin by analyzing the factors leading to poor TTR control. The most valuable finding of this study is that marked fluctuations of brain natriuretic peptide levels in patients with complication of heart failure was a risk factor for poor TTR control. Identification of the factors leading to the poor TTR control is useful for making the decision to switch to other anticoagulants, such as dabigatran or apixaban, or to continue warfarin by correcting risk factors in atrial fibrillation patients receiving long-term warfarin therapy.

Elastic stiffness of a Skyrmion crystal

We observe the elastic stiffness and ultrasonic absorption of a Skyrmion crystal in the chiral-lattice magnet MnSi. The Skyrmion crystal lattice exhibits a stiffness 3 orders of magnitude smaller than that of the atomic lattice of MnSi, being as soft as the flux line lattice in type-II superconductors. The observed anisotropic elastic responses are consistent with the cylindrical shape of the Skyrmion spin texture. Phenomenological analysis reveals that the spin-orbit coupling is responsible for the emergence of anisotropic elasticity in the Skyrmion lattice.

Common origin of the circular-dichroism pattern in angle-resolved photoemission spectroscopy of SrTiO3 and Cu(x)Bi2Se3

Circular dichroism in the angular distribution of photoelectrons from SrTiO(3):Nb and Cu(x)Bi(2)Se(3) is investigated by 7-eV laser angle-resolved photoemission spectroscopy. In addition to the well-known node that occurs in the circular dichroism pattern when the incidence plane matches the mirror plane of the crystal, we show that another type of node occurs when the mirror plane of the crystal is vertical to the incidence plane and the electronic state is two-dimensional. The flower-shaped circular dichroism patterns in the angular distribution occurring around the Fermi level of SrTiO(3):Nb and around the Dirac point of Cu(x)Bi(2)Se(3) are explained on equal footings. We point out that the penetration depth of the topological states of Cu(x)Bi(2)Se(3) depends on momentum.

Triakontadipole and high-order dysprosium multipoles in the antiferromagnetic phase of DyB2C2

Resonant soft x-ray Bragg diffraction at the Dy M(4,5) edges has been used to study Dy multipoles in the combined magnetic and orbitally ordered phase of DyB(2)C(2). The analysis incorporates both the intra-atomic magnetic and quadrupolar interactions between the 3d core and 4f valence shells. Additionally, we introduce to the formalism the interference of magnetic and nonmagnetic oscillators. This allows a determination of the higher-order multipole moments of rank 1 (dipole) to 6 (hexacontatetrapole). The strength of the Dy 4f multipole moments have been estimated as being up to 80% of the quadrupolar moment.

X-ray diffractometer combining synchrotron radiation and pulsed magnetic fields up to 40 T

A synchrotron X-ray diffractometer incorporating a pulsed field magnet for high fields up to 40 T has been developed and a detailed description of this instrument is reported. The pulsed field magnet is composed of two coaxial coils with a gap of 3 mm at the mid-plane for passage of the X-rays. The pixel detector PILATUS 100K is used to store the diffracted X-rays. As a test of this instrument, X-ray diffraction by a powder sample of the antiferromagnet CoO is measured below the Néel temperature. A field-dependent lattice distortion of CoO due to magnetostriction is observed up to 38 T.

Thermodynamic properties in the approach to the quantum critical point of the spin-ladder material Na2Co2(C2O4)3(H2O)2

Magnetic susceptibility and heat capacity measurements as a function of temperature on a single-crystal sample of a spin-ladder material, Na2Co2(C2O4)3(H2O)2, are reported. Principal susceptibilities, parallel and perpendicular to the ladder direction, respectively, show broad maxima around 22 and 17 K. Both susceptibilities decay exponentially down to about 5 K and thereafter they are essentially independent of temperature. These findings amount to a signature of a quantum phase transition from a spin-liquid to Néel ordered state previously predicted theoretically. No anomaly is found in the heat capacity around the transition temperature.

Prevention of the rehaemorrhage of bleeding peptic ulcers: effects of Helicobacter pylori eradication and acid suppression

AIM

This study aimed to investigate the consequences of Helicobacter pylori eradication and acid suppression on rehaemorrhage caused by bleeding peptic ulcers.

METHODS

A total of 320 patients who had been diagnosed with bleeding peptic ulcers between January 1994 and December 2001 were included in the study. Cases between 1994 and 1997, prior to the introduction of eradication therapy, were assigned to group A, whereas those between 1998 and 2001, after the eradication therapy, were assigned to group B.

RESULTS

Of the 320 cases, 162 were designated as group A (113 gastric ulcers and 49 duodenal ulcers) and 158 as group B (116 and 42, respectively). Rehaemorrhage occurred in 24 cases (15%) and five cases (3%) in groups A and B, respectively, presenting a significantly decreased rate of rehaemorrhage in group B. Among those without eradication, rehaemorrhage was observed in 15 of 128 cases (12%) that received treatment with histamine(2)-receptor antagonist (famotidine), and 14 of 142 cases (10%) treated with proton-pump inhibitors, with no significant difference between the two.

CONCLUSIONS

Helicobacter pylori eradication lowered the rates of rehaemorrhage. Treatment with histamine(2)-receptor antagonist or proton-pump inhibitors did not produce a difference in the rate of rehaemorrhage.

[Analysis of angiographic computed tomography with rapid helical scan. Clinical usefulness for the diagnosis of hepatocellular carcinoma]

PURPOSE

The aim of this study was to clarify the clinical usefulness of combined CT during arterial portography (CTAP), and CT arteriography (CTA), for the diagnosis of hepatocellular carcinoma.

MATERIALS AND METHODS

CTAP and CTA were performed in 58 patients with a combined 144 hepatocellular carcinoma (HCC) lesions. Arterial vascular access was obtained through bilateral punctures of the femoral artery with selective placement of catheters in the hepatic artery and superior mesenteric artery. CT scans were performed first during injection of contrast media into the superior mesenteric artery, followed by repeated imaging of the liver during injection of contrast media into the hepatic artery. Delayed CT (DCT) was also obtained 5 min after CTA.

RESULTS

The detection rates for all 144 lesions were 73.6% with conventional contrast enhanced CT, 90.3% with CTAP, 95.8% with CTA, 87.5% with DCT, and 98.6% with combined CTAP and CTA. Of early HCC lesions (n = 18), 88.9%, 33.3%, 77.8%, 100%, and 88.9% were detected by conventional contrast enhanced CT, CTAP, CTA, DCT, and combined CTAP and CTA, respectively. Of classical HCC lesions (n = 126), 71.4%, 98.4%, 98.4%, 85.7%, and 100% were detected by conventional contrast enhanced CT, CTAP, CTA, DCT, and combined CTAP and CTA, respectively.

CONCLUSION

Combining CTAP and CTA improved the radiologist's ability to detect lesions with confidence and to differentiate perfusion abnormalities of HCCs.

[Clinical statistics on in-patients and operations during a 20-year period (1975-1994) at Department of Urology, Kansai Medical University]

The patients, diseases and operations experienced between 1975 and 1994 in our department were statistically analyzed. The numbers of in-patients and operations have been increasing since 1977. During these 20 years, endoscopic surgery has replaced many open surgical procedures. The introduction of extracorporeal shock wave lithotripsy has dramatically changed the therapeutic modality for urolithiasis, and decreased of the necessity of open surgery.

[Clinical efficacy of the Porges Urospiral, a reversible intraprostatic spiral stent, in patients with benign prostatic hypertrophy]

The Porges Urospiral, a urethral spiral stent made of stainless steel wire, is designed for patients with benign prostatic hypertrophy. To evaluate the safety and efficacy of the stent, a prospective uncontrolled study was performed on 60 patients who complained of urinary retention (48 patients) or severe dysuria (12 patients) due to prostatic hypertrophy. Four patients had neurogenic disorders resulting in bladder dysfunction. The average age of the patients was 77.4 years old, ranging from 61 to 91 years old. In 48 patients, the stent was used instead of transurethral resection of the prostate (TUR-P) because of the patients poor general conditions, while in 12 patients the stent was transiently used until TUR-P. Subjective symptoms, according to an original scoring system, and objective signs, uroflowmetry measurements and residual urine volume, before and 3 months after stent insertion were compared. The stent was indwelt for more than 3 months in 40 of the 57 patients in whom the stent could be inserted. Out of 37 evaluable patients, subjective symptoms improved in all the patients and objective symptoms improved in 26 patients (70.3%). Complications included urinary incontinence, urination pain, urethral pain, gross hematuria or migration of the stent. Although these complications disappeared in a few days after the insertion of the stent in a majority of the patients, the stent was removed in 17 patients due to complications within 3 months after insertion. The overall clinical efficacy of this stent was 56% in 50 evaluable patients who had no neurogenic disorders.(ABSTRACT TRUNCATED AT 250 WORDS)

Statistics of photoelectric pulses for Gaussian-Lorentzian light

The practical treatment of statistics for Gaussian-Lorentzian light is studied theoretically and experimentally by using the time interval distribution of photoelectric pulses, which is derived in two approaches that are based on Markovian processes and the generating function of photon counting statistics, taking the experimental conditions into account. The limits of the validity of the Markovian assumption are made clear. In arbitrary light intensity it is valid experimentally to employ the practical generating function of photon counting distribution expressed as the product of an ideal generating function and a Poissonian one.