Observation of Collective Resonance Modes in a Chiral Spin Soliton Lattice with Tunable Magnon Dispersion.

A chiral spin soliton lattice (CSL), one of the representative systems of a magnetic superstructure, exhibits reconfigurability in periodicity over a macroscopic length scale. Such coherent and tunable characteristics of the CSL lead to an emergence of elementary excitation of the CSL as phononlike modes due to translational symmetry breaking and bring a controllability of the dispersion relation of the CSL phonon. Using a broadband microwave spectroscopy technique, we directly found that higher-order magnetic resonance modes appear in the CSL phase of a chiral helimagnet CrNb_{3}S_{6}, which is ascribed to the CSL phonon response. The resonance frequency of the CSL phonon can be tuned between 16 and 40 GHz in the vicinity of the critical field, where the CSL period alters rapidly. The frequency range of the CSL phonon is expected to extend over 100 GHz as extrapolated on the basis of the theoretical model. The present results indicate that chiral helimagnets could work as materials useful for broadband signal processing in the millimeter-wave band.

Anomalous Temperature Behavior of the Chiral Spin Helix in CrNb_{3}S_{6} Thin Lamellae.

Using Lorentz transmission electron microscopy and small-angle electron scattering techniques, we investigate the temperature-dependent evolution of a magnetic stripe pattern period in thin-film lamellae of the prototype monoaxial chiral helimagnet CrNb_{3}S_{6}. The sinusoidal stripe pattern appears due to formation of a chiral helimagnetic order (CHM) in this material. We found that as the temperature increases, the CHM period is initially independent of temperature and then starts to shrink above the temperature of about 90 K, which is far below the magnetic phase transition temperature for the bulk material T_{c} (123 K). The stripe order disappears at around 140 K, far above T_{c}. We argue that this cascade of transitions reflects a three-stage hierarchical behavior of melting in two dimensions.

Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscope.

We demonstrate that light-induced heat pulses of different duration and energy can write Skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz transmission electron microscopy, we directly resolve the spatiotemporal evolution of the magnetization ensuing optical excitation. The Skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-µs to µs range, depending on the cooling rate of the system.

First Determination of the Level Structure of an sd-Shell Hypernucleus, _{Λ}

We report on the first observation of γ rays emitted from an sd-shell hypernucleus, _{Λ}^{19}F. The energy spacing between the ground state doublet, 1/2^{+} and 3/2^{+} states, of _{Λ}^{19}F is determined to be 315.5±0.4(stat)_{-0.5}^{+0.6}(syst) keV by measuring the γ-ray energy of the M1(3/2^{+}→1/2^{+}) transition. In addition, three γ-ray peaks are observed and assigned as E2(5/2^{+}→1/2^{+}), E1(1/2^{-}→1/2^{+}), and E1(1/2^{-}→3/2^{+}) transitions. The excitation energies of the 5/2^{+} and 1/2^{-} states are determined to be 895.2±0.3(stat)±0.5(syst) and 1265.6±1.2(stat)_{-0.5}^{+0.7}(syst) keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s- and p-shell hypernuclear data.

Dermoscopic features of pseudoxanthoma elasticum.

Pseudoxanthoma elasticum (PXE) is a disease characterized by aberrant mineralization of soft tissue and fragmentation of elastic fibres. It is often difficult to distinguish PXE clinically from pseudoxanthoma elasticum-like papillary dermal elastolysis (PXE-like PDE). However, we have identified that the dermoscopic findings in PXE include coalescing and reticulated yellow-white clods on a light purple-red background, whereas the dermoscopic findings in PXE-like PDE lack such a coloured background. To our knowledge, this is the first detailed description of dermoscopic differences between PXE and PXE-like PDE.

Chiral Surface Twists and Skyrmion Stability in Nanolayers of Cubic Helimagnets.

Theoretical analysis and Lorentz transmission electron microscopy (LTEM) investigations in an FeGe wedge demonstrate that chiral twists arising near the surfaces of noncentrosymmetric ferromagnets [Meynell et al., Phys. Rev. B 90, 014406 (2014)] provide a stabilization mechanism for magnetic Skyrmion lattices and helicoids in cubic helimagnet nanolayers. The magnetic phase diagram obtained for freestanding cubic helimagnet nanolayers shows that magnetization processes differ fundamentally from those in bulk cubic helimagnets and are characterized by the first-order transitions between modulated phases. LTEM investigations exhibit a series of hysteretic transformation processes among the modulated phases, which results in the formation of the multidomain patterns.

Interlayer magnetoresistance due to chiral soliton lattice formation in hexagonal chiral magnet CrNb3S6.

We investigate the interlayer magnetoresistance (MR) along the chiral crystallographic axis in the hexagonal chiral magnet CrNb3S6. In a region below the incommensurate-commensurate phase transition between the chiral soliton lattice and the forced ferromagnetic state, a negative MR is obtained in a wide range of temperature, while a small positive MR is found very close to the Curie temperature. Normalized data of the negative MR almost falls into a single curve and is well fitted by a theoretical equation of the soliton density, meaning that the origin of the MR is ascribed to the magnetic scattering of conduction electrons by a nonlinear, periodic, and countable array of magnetic soliton kinks.

Chiral magnetic soliton lattice on a chiral helimagnet.

Using Lorenz microscopy and small-angle electron diffraction, we directly present that the chiral magnetic soliton lattice (CSL) continuously evolves from a chiral helimagnetic structure in small magnetic fields in Cr(1/3)NbS2. An incommensurate CSL undergoes a phase transition to a commensurate ferromagnetic state at the critical field strength. The period of a CSL, which exerts an effective potential for itinerant spins, is tuned by simply changing the field strength. Chiral magnetic orders observed do not exhibit any structural dislocation, indicating their high stability and robustness in Cr(1/3)NbS2.

Probing microwave fields and enabling in-situ experiments in a transmission electron microscope.

A technique is presented whereby the performance of a microwave device is evaluated by mapping local field distributions using Lorentz transmission electron microscopy (L-TEM). We demonstrate the method by measuring the polarisation state of the electromagnetic fields produced by a microstrip waveguide as a function of its gigahertz operating frequency. The forward and backward propagating electromagnetic fields produced by the waveguide, in a specimen-free experiment, exert Lorentz forces on the propagating electron beam. Importantly, in addition to the mapping of dynamic fields, this novel method allows detection of effects of microwave fields on specimens, such as observing ferromagnetic materials at resonance.

Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi2Sr2CaCu2O(y)

We studied the conduction noise spectrum in the vortex state of a high-temperature superconductor, Bi(2)Sr(2)CaCu(2)O(y), subject to a uniform driving force. Two characteristic features, a broad-band noise (BBN) and a narrow-band noise (NBN), were observed in the vortex-solid phase. The origin of the large BBN was determined to be plastic motion of the vortices, whereas the NBN was found to originate from the washboard modulation of the translational velocity of the driven vortices. We believe this to be the first observation of washboard noise of dc driven vortices in any superconductor.

Spatial versus temporal stability issues in image processing neuro chips.

A typical image processing neuro chip consists of a regular array of very simple cell circuits. When it is implemented by a CMOS process, two stability issues naturally arise. First, parasitic capacitors of MOS transistors induce temporal dynamics. Since a processed image is given as the stable limit point of the temporal dynamics, a temporally unstable chip is unusable. Second, because of the array structure, the node voltage distribution induces spatial dynamics, and it could behave in a wild manner, e.g. oscillatory. The main contributions are: (i) a clarification of the spatial stability issue; (ii) explicit if and only if conditions for the temporal and the spatial stability in terms of circuit parameters; (iii) a rigorous explanation of the fact that even though the spatial stability is stronger than the temporal stability, the set of parameter values for which the two stability issues disagree is of (Lebesgue) measure zero; and (iv) theoretical estimates of the processing speed.

Minimal incision transinguinal repair for incarcerated obturator hernia.

BACKGROUND: Patients with incarcerated obturator hernia are usually elderly, frail, and physically inactive women with serious comorbidities. Although a laparotomy is standard surgical intervention for emergency incarcerated or strangulated obturator hernia, it is invasive particularly for these high-risk patients. The aim of this study is to show the feasibility of minimum open inguinal approach to reduce surgical risk for preoperatively diagnosed incarcerated obturator hernia. METHODS: Between April 2008 and July 2012, 3 consecutive incarcerated obturator hernia patients at Kamitsuga General Hospital who were diagnosed preoperatively by computed tomography underwent the following procedure. First a 4 cm inguinal hernia incision and preperitoneal dissection through the opening of the deep inguinal ring are made. The obturator hernia can be easily found 2 cm dorsally from the Cooper's ligament extraperitoneally. A small incision is made at medial sharp edge of the hernia defect. The hernia sac and its content can then be reduced. If the incarcerated bowel is viable, a prosthetic mesh is placed as a patch. If the bowel is necrotic, the damaged bowel loop is withdrawn through the wound and easily reconstructed extra-abdominally. RESULTS: All operations were successfully completed with this procedure. All patients recovered without incident. CONCLUSIONS: Minimal incision transinguinal repair for diagnosed incarcerated obturator hernia is feasible and provides an improved option to more invasive procedures.

Dramatic Clinical Response of Relapsed Metastatic Extramammary Paget's Disease to Trastuzumab Monotherapy.

We report the first case of 68-year-old Japanese woman with metastatic HER2-positive extramammary Paget's disease that showed the validity of trastuzumab monotherapy. We administered trastuzumab at a loading dose of 8 mg/kg i.v., followed by a 6 mg/kg maintenance dose every three weeks according to a protocol for HER2-positive metastatic breast cancers and a near-complete response was achieved after the tenth infusion. The patient experienced a moderate headache and flushing during the first infusion, but had no advanced effects during subsequent infusions with ibuprofen and d-chlorpheniramine maleate. Given the dramatic response, the patient has had 17 infusions of trastuzumab with no disease progression. Thus, trastuzumab has few side effects and is well tolerated for elderly patients. It may become a new choice of the adjubant therapy of this disease.

Melanoma in association with acquired melanocytic nevus in Japan: a review of cases in the literature.

BACKGROUND: Malignant melanomas clinically and/or histologically associated with melanocytic nevi have been reported worldwide. Approximately 20% of malignant melanomas in Caucasians, most of which are found on the trunk and proximal extremities, develop in association with pre-existing melanocytic nevi. In Japan, however, over half of all melanomas are acral lentiginous melanomas (ALMs) on the hands and feet; melanomas on sun-exposed areas are seen less frequently in Japanese people than in Caucasians. As ALMs are not usually accompanied by melanocytic nevi and there have been no reviews of the literature or statistical data regarding Japanese cases of melanomas with melanocytic nevi, dermatologists in Japan have few opportunities to see melanomas associated with pre-existing melanocytic nevi. METHODS: Here we report a case of a superficial spreading melanoma that was formed on a melanocytic nevus on the trunk, and we review for the first time the case reports from the Japanese literature. RESULTS AND CONCLUSIONS: With regard to the reported cases, melanomas associated with melanocytic nevi were mainly superficial spreading melanomas and nodular melanomas on the trunk or extremities; ALMs were rarely associated with nevi, indicating a trend similar to that observed in Caucasians. These findings suggest that the low frequency of associations between melanomas and melanocytic nevi in Japan reflects racial differences in the frequencies of each type of melanoma.

[Experimental study on the effect of direct currents on the internal remodeling of a long bone cortex].

The effects of direct currents on internal remodeling were examined using femurs of 21 adult mongrel dogs. The left femurs of all dogs, used as a control, were inserted electrodes only, which were not electrically stimulated. In Group 1, no surgery was done on the right femur. In Group 2, 1 microA continuous direct current (D. C.) was applied for 6 weeks; in Group 3, 10 microA for 2 weeks; in Group 4, 10 microA for 4 weeks; in Group 5, 10 microA for 6 weeks; in Group 6, 10 microA for 16 weeks; and in Group 7 100 microA for 6 weeks. Each group was composed of three dogs. The following histomorphometric parameters were measured to evaluate the effects of electrical stimulation: number of resorption cavities (Ar), number of secondary osteons with osteoid seam (osAf), linear rate of mineralization of osteoid seam (Mo), perimeter of osteoid seam (Sf), cross-sectional area of secondary osteon (Ah) and bone formation rate (Vf). The following results were obtained: In Group 1, resorption cavities and secondary osteon with osteoid seam were observed more in the left femur than in the right. Then, mechanical stimulation of periosteal stripping or cortical drilling enhanced internal remodeling of cortical bone. In other groups (electrical stimulation was applied on the right femur), it seems that internal remodeling, especially activation frequency, was enhanced by D. C. No significant change was noted in the linear rate of mineralization of osteoid seam and cross-sectional area of the secondary osteons. Bone formation rate in the right femur showed increment when length of stimulating period had increased from 2 to 6 weeks. In Group 6 and 7, the enhanced area of bone formation has increased in cross-section, although in Group 7, bone necrosis was observed around the electrode in the right femur. Therefore, the optimum current of electrical stimulation may be just or slightly more than 10 microA. Bone formation rate was correlated with volume of callus in the marrow cavity within the period of six weeks.