Effective field theory for Sp(N) antiferromagnets and its phase structure

In this paper, we study quantum Sp(N) antiferromagnetic (AF) Heisenberg models in two dimensions (2D) by using the Schwinger-boson representation and the path-integral methods. An effective field theory, which is an extension of CP^{N-1} model in (2+1)D, is derived and its phase structure is studied by the 1/N-expansion. We introduce a spatial anisotropy in the exchange couplings and show that the effective coupling constant in the CP^{N-1} model is an increasing function of the anisotropy. For the SU(N) AF Heisenberg model, which is a specific case of the Sp(N) model, we found that phase transition from the ordered "N\'eel state" to paramagnetic phase takes place as the anisotropy is increased. In the vicinity of the SU(N) symmetric point, this phase structure is retained. However as a parameter that controls explicit breaking of the SU(N) symmetry is increased, a new phase, which is similar to the spiral-spin phase with a nematic order in frustrated SU(2) spin systems, appears. It is shown that at that phase transition point, a local SU(2) gauge symmetry with composite SU(2) gauge field appears in the low-energy sector. It is another example of symmetry-enhancement phenomenon at low energies. We also introduce a lattice gauge-theoretical model, which is a counterpart of the effective field theory, and study its phase structure by means of the Monte-Carlo simulations.Comment: 30 pages, 15 figure

Ziram, a dithiocarbamate fungicide, exhibits pseudo-cytoprotective actions against oxidative stress in rat thymocytes : Possible environmental risks

Ziram, a dithiocarbamate fungicide, protects various vegetables and fruits against infections by fungus. Recently, there have been increasing anxieties about the risks in the use of dithiocarbamate fungicides. Our previous studies showed that Zn2+ was a determinant of Ziram cytotoxicity. In addition, Zn2+ is linked to H2O2 cytotoxicity. Therefore, in this study, we aimed to test the hypothesis that Ziram could augment the cytotoxicity of H2O2 by examining the changes induced by Ziram in some cellular parameters in rat thymic lymphocytes subjected to H2O2-induced oxidative stress using flow-cytometric methods with fluorescent dyes. Ziram significantly attenuated H2O2-induced cell death at sublethal concentrations. However, in the cells under oxidative stress elicited by H2O2, Ziram promoted the changing over from intact cells to living cells with exposed phosphatidylserine (PS) on plasma membranes, whereas it inhibited the transition from PS-exposed living cells to dead cells. Ziram significantly augmented H2O2 actions, including reduction of cellular glutathione levels and elevation of intracellular Zn2+ concentrations. Conversely, it attenuated H2O2-induced depolarization of mitochondrial membrane potential. Ziram at sublethal concentrations seems to exhibit promotive and suppressive actions on the process of cell death caused by H2O2. Ziram increased the number of living cells with exposed PS, a phenomenon characteristic of early stages of apoptosis. Thus, it is concluded that Ziram exhibits pseudo-cytoprotective actions against H2O2- induced oxidative stress

Highly sensitive spectral interferometric fourwave mixing microscopy near the shot noise limit and its combination with two-photon excited fluorescence microscopy

Isobe K., Ozeki Y., Kawasumi T., et al. Highly sensitive spectral interferometric fourwave mixing microscopy near the shot noise limit and its combination with two-photon excited fluorescence microscopy. Optics Express, 14, 23, 11204. https://doi.org/10.1364/OE.14.011204

Image Quality of the Coronary Angiography with Noise Reduction Technology to Decrease the Radiation Dose

We examined the effects of a reduced exposure dose on the quality of images from an angiography device augmented with a noise reduction algorithm. Before its clinical application, we compared the diameter of the discrimination limit of the hole with that in the conventional method by a visual evaluation with a contrast-detail (C-D) phantom imaged using the target dose. Based on the results, a reducible dose was determined and applied clinically. The sample population consisted of patients being followed up after percutaneous coronary intervention (PCI) for coronary artery disease; we evaluated the effects of the exposure reduction on image quality. A significant dose reduction was observed by the noise-reduction method compared to the conventional method; the radiation dose to the flat panel detector (FPD) could be reduced to 70 nGy per frame. Clinically, a dose reduction of approx. 40% was obtained while maintaining image quality almost equal to that of the conventional method

Variations of cosmic noise absorption (CNA) by energetic electron precipitation (EEP) and changes of the auroral morphology

The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. / Institute of Statistics and Mathematics (ISM) Seminar room 2 (D304) (3rd floor

A case of Falciparum malaria without getting serious by early therapeutic intervention

A １７years old man studying in Nigeria came back to Japan three days before hospitalization date. He came to our emergency department with fever, headache and epigastric pain from the day before. At first, I couldn’t diagnose with physical examination, blood test and image inspection. But my leader suggested that possibility of malaria because of his travel history. Then we checked his peripheral blood smear and found a malaria parasite. Immediately, we hospitalized him and started antimalarial drug. ３ days after admission, fever went down, and malaria parasite disappeared in peripheral blood smear. He discharged in ７ days after admission. A polymerase chain reaction of Plasmodium falciparum was positive at a later date. Plasmodium falciparum is often to become severe, and it is important to diagnose early onset. Our case suggests that rapid diagnostic kit and peripheral blood smear are useful to diagnose malaria, and early therapeutic intervention may prevent severe malaria and complications

Spatial Evolution of Wave‐Particle Interaction Region Deduced From Flash‐Type Auroras and Chorus‐Ray Tracing

In-situ observations of spatial variations of the wave-particle interaction region require a large number of satellite probes. As an alternative, flash-type auroras, a kind of pulsating aurora, driven by discrete chorus elements, can be used to investigate the interaction region with a high spatial resolution. We estimated the spatial extent of wave-particle interaction region from ground-based observations of flash aurora at Gakona (62.39°N, 214.78°E), Alaska at subauroral latitudes, and found that the auroral expansion was predominantly to the low-latitude side. The spatial displacement is thought to be caused by the propagation effects of chorus waves in the magnetosphere. Using ray tracing analysis to take into account chorus wave propagation, we reconstructed the spatiotemporal evolution of the volume emission rate and confirmed that the predominant expansion is toward the lower-latitude side in the ionosphere. This study shows that chorus wave propagation in the magnetosphere gives new insight for characterizing the transverse size (across the geomagnetic field line) of wave-particle interaction regions. The calculated spatial scale of the column auroral emission shows a correlation with the magnetic latitude of the resonance region at magnetic latitudes within 10° of the equatorial plane of the magnetosphere. Our results suggest that the spatial scale of a flash aurora is indirectly related to the chorus amplitude because the latitudinal range of the wave-particle interaction is important for the growth of wave amplitude