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.

First Determination of the Level Structure of an sd-Shell Hypernucleus, _{Λ}^{19}F

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.

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.

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.

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.

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.

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.

Flow Analysis of Injection-Press Molding Process

We developed a method to determine the characteristics of a press machine required for the injection-press molding process. In this paper, a model based on a serial spring connecting two different springs was used. One was spring represented apparent machine rigidity and the other the resistance to compression of the resin. Using this model, we calculated the flow between parallel plates and flow behavior in a “tray” mold.

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.

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.

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.

Squamous metaplasia of Paget's disease

A patient had triple extramammary Paget's disease of both axillary and genital regions. Right inguinal lymphadenopathy was found 1 year after excision of all the skin lesions. Excisional biopsy of the lymph node demonstrated a mixture of Paget cells and atypical squamoid cells with horn pearls suggestive of keratinization. The squamoid cells were positive for cytokeratin 10, a marker of suprabasal epidermis, and also positive for laminin gamma2 which is often expressed in invasive squamous cell carcinoma. The coexistence of these different cells within the same tumour island suggested that the squamoid cells derived from metaplasia of Paget cells.

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.

Assessment of bone density in the distal radius with computer assisted X-ray densitometry (CXD)

A modified and improved radiographic absorptiometry of the distal radius which enables on-site analysis, called computer assisted X-ray densitometry (CXD), was evaluated from the viewpoint of quality assessment. Its precision and the correlation with dual energy X-ray absorptiometry (DXA) was evaluated in 12 volunteers (mean age 44.7 years). The profile of CXD-measured radial bone mineral density (RBMD) from 142 subjects (75 premenopausal and 67 postmenopausal women, mean ages 44.9 and 50.6 years, respectively) were compared with previous data by other methodologies of bone mineral analysis. The intra-assay coefficient of variation (CV) was 0.617%, the inter-assay CV was 2.064%, and the inter-observer CV was 0.673%. The correlation between CXD-measured RBMD and DXA-measured RBMD was of statistical significance (r2 = 0.733, P < 0.01). The correlation of CXD-measured RBMD with age, height or weight corresponded well with previous reports. CXD-measured RBMD and DXA-measured vertebral bone mineral density (VBMD) also had a significant positive correlation, but their correlation was not so close (r2 = 0.149, P < 0.01). The discriminative ability of osteoporosis by CXD was of acceptable level (odd's ratio = 5.72, P < 0.05), when assessed by comparison with bone dystrophy score (BDS) on the plain vertebral radiogram. Although some problems remain in technical standardization, CXD could be an easy, inexpensive, and widely applicable alternative of non-weight bearing cancellous bone densitometry.

Doppler color flow imaging in the detection and quantitative measurement of the gastroduodenal artery blood flow

The purpose of this article was to investigate the detection rate of gastroduodenal artery blood flow (GDABF), and to measure its velocity and volume flow rate using Doppler color imaging. The GDABF was detected in 40 of 41 (98%) normal subjects with longitudinal scanning and in 36 (88%) with transverse scanning. The velocity of the GDABF was 21 +/- 8 cm/sec (m +/- SD) and the volume flow rate was 67 +/- 20 mL/min. Without color Doppler, the vascular lumina of the GDA was demonstrated in 27 (66%) subjects by longitudinal scanning and in 26 (63%) by transverse scanning. The hemodynamics of the GDA were revealed noninvasively using Doppler ultrasonography in a patient with a malignant islet cell tumor of the pancreas and one with a ductal cell carcinoma of the pancreas.

Dependence on pH of permeability towards electrolyte ions of poly(L-lysine-alt-terephthalic acid) microcapsule membranes

Permeation of electrolyte ions through poly(L-lysine-alt-terephthalic acid) microcapsule membranes was studied as a function of the pH of the medium at different ionic strengths. When the pH of the medium was varied, the permeation rate for 5-sulphosalicylate anions, as well as phenyltrimethylammonium cations, was slow at pH values lower than 4, showed a sudden and large increase in the pH range between 4 and 6, and thereafter remained unchanged. This remarkable change in the permeation rate was found to be produced by an abrupt increase in the microcapsule size observed in the same pH range. Increase in the ionic strength of the medium at pH values higher than 6 increased the rate of anion permeation but decreased the rate of cation permeation due to increase in the screening effect of salt ions on the negative charges in the microcapsule membranes.

Quantification of physical and cyto-physiological conditions for the electrofusion of Saccharomyces cerevisiae

Various conditions for obtaining hybrids of the auxotrophic mutants SH1509 and SH1512 of Saccharomyces cerevisiae by electrofusion were investigated. An AC field of 400 Vp/cm and a DC field of 2 square pulses (7 kV/cm; 60 microsec each) at an interval of 0.5 sec were effective. Treatment with 0.2 (SH1509) or 1.0 mg/ml (SH1512) Zymolyase for 1 or 1.5 hr was essential. As to the molarity of the osmotic stabilizer (sorbitol), the hybrid yield peaked at 0.6 M. The presence of CaCl2 (up to 0.4 mM) or 0.1 mM CaCl2 with 0.1 mM MgCl2 enhanced the yield. The temperature of the spheroplast suspension during pulsations also affected the yield, the most suitable temperature being 28 degrees C.

The diagnostic accuracy of magnetic resonance imaging in pancreatic carcinoma based on a retrospective analysis of vascular involvement

A retrospective analysis was made to evaluate the diagnostic accuracy of magnetic resonance (MR) imaging for pancreatic cancer. Twenty-one lesions from 21 patients with pancreatic cancer were examined and all except one, were identified on MR images by a disparity in contrast and/or morphological enlargement. The patients were divided into 3-groups, based on the relationship between the tumor and the portal vein, seen on the MR images. These groups were defined as the separate, touching, and surrounding groups. The MR findings correlated with the findings at laparotomy in 16 patients, 10 of whom underwent tumor excision. In the remaining 4, the MR findings correlated with the angiographic findings. The presence or absence of vascular involvement was correctly diagnosed in 18 of the 21 patients. MR imaging proved useful for detecting pancreatic cancer and cancerous infiltration into the portal vein. MR imaging should therefore aid the surgeon in determining the operability and/or curability of patients with pancreatic cancer.

Enhanced antitumor efficacy with a combination of hyperthermochemotherapy and thermosensitization with polyamine antimetabolites in nude mice

In an attempt to enhance the antitumor effects of hyperthermochemotherapy, methylglyoxal-bis-guanylhydrazone (MGBG) and alpha-difluoromethylornithine (DFMO) were used in combination with hyperthermochemotherapy of 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitrosoure a (ACNU) against human gastric cancer (ST-2) xenotransplanted into nude mice. After priming with DFMO and MGBG, ACNU was given ip and subsequently, a 23 minute-hyperthermia was carried out by placing the leg with the tumor into a water bath of a temperature of 43.5 +/- 0.1 degrees C. The second hyperthermic treatment was given in the same manner after 48 hours. MGBG and DFMO were administered for 4 successive days from the previous day of the first hyperthermia. In mice treated with DFMO plus MGBG, either tumor growth or tumor tripling time was much the same as in the control, while in mice given MGBG, DFMO plus heat, there was a diminution in tumor growth. Hyperthermia together with MGBG, DFMO plus ACNU brought about remarkable antiproliferative effects on ST-2 tumor growth, compared to three regimens with MGBG, DFMO plus heat, MGBG, DFMO plus ACNU, as well as ACNU plus heat. These data suggest that a combination of MGBG with DFMO leads to a favorable thermosensitization to the antitumor efficacy of ACNU.

Combined therapy of polyamine antimetabolites and antitumor drugs for human gastric cancer xenotransplanted into nude mice

Antitumor therapies using polyamine antimetabolites combined with 1-(4-amino-2-methyl-5-pyrimidyl)methyl-3(2-chloroethyl)-3-nitrosourea (ACNU) or fluorinated pyrimidines for human gastric cancer xenotransplanted into nude mice were studied to determine inhibiting post-therapeutic regrowth of the tumor after cessation of antitumor treatments with polyamine antimetabolites alone. ACNU 20 mg/kg, fluorinated pyrimidine, 5-FU 52.8 mg/kg and 5'-deoxy-5-fluorouridine (5'-DFUR) 100 mg/kg as well as polyamine antimetabolites, alpha-difluoromethylornithine (DFMO) 1000 mg/kg and methylglyoxal-bis-guanylhydrazone (MGBG) 50 mg/kg were given intraperitoneally for 5 successive days. When DFMO and MGBG were combined with ACNU, the post-therapeutic regrowth was definitely inhibited, while combined treatments with 5-FU or 5'-DFUR did not inhibit the regrowth. Post-therapeutic DNA biosynthesis was suppressed in mice given DFMO, MGBG plus ACNU. On the contrary, in mice treated with DFMO, MGBG plus 5-FU or 5'-DFUR, suppression of DNA biosynthesis was not observed. Tumor tissue spermine levels in the DFMO, MGBG plus 5-FU or 5'-DFUR group remained unchanged, compared to those in the DFMO + MGBG group. In mice given DFMO, MGBG plus ACNU, however, spermine levels were markedly depressed; and the ACNU alone depressed also the tissue spermine levels. These different results between nitrosourea and fluorinated pyrimidines may relate to mechanisms of action of these antitumor drugs.

[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.

[Effect of tiemonium iodide on colonic motility in dogs]

Effects of tiemonium iodide (tiemonium, 20 micrograms/kg), mepenzolate bromide (mepenzolate, 20 micrograms/kg), butylscopolamine bromide (butylscopolamine, 50 micrograms/kg) and atropine sulfate (atropine, 10 micrograms/kg) on the colonic motility in dogs were evaluated using a balloon method. The frequency of the wave motion was analyzed by fast Fourier transform, and the power spectra were obtained. The value of the first term of the power spectrum is regarded as an indication of the colonic tonus. Inhibitory effects of tiemonium on both the normal proximal colonic motility and the accelerating motility induced by neostigmine metylsulfate (neostigmine, 50 micrograms/kg) were equal to those of butylscopolamine. In the case of distal colonic motility, tiemonium showed potent mepenzolate-like inhibition. When the drugs were injected into the veins after administration of PGF2 alpha (10 micrograms/kg), all of the drugs depressed the colonic constriction induced by PGF2 alpha. The colonic motility was not restored by the administration of tiemonium or mepenzolate before the injection of PGF2 alpha, but such an effect was not observed in the case of butylscopolamine and atropine. It is suggested that tiemonium shows an extensive inhibition on the colonic motility in the mode of mepenzolate-like action and by some additional mechanism.