Dependence of exciton transition energy of single-walled carbon nanotubes on surrounding dielectric materials

We theoretically investigate the dependence of exciton transition energies on dielectric constant of surrounding materials. We make a simple model for the relation between dielectric constant of environment and a static dielectric constant describing the effects of electrons in core states, $\sigma$ bonds and surrounding materials. Although the model is very simple, calculated results well reproduce experimental transition energy dependence on dielectric constant of various surrounding materials.Comment: 5pages, 4 figure

<Advanced Energy Conversion Division> Nano Optical Science Research Section

3-1. Research Activities in 202

Performance of the Charge Injection Capability of Suzaku XIS

A charge injection technique is applied to the X-ray CCD camera, XIS (X-ray Imaging Spectrometer) onboard Suzaku. The charge transfer inefficiency (CTI) in each CCD column (vertical transfer channel) is measured by the injection of charge packets into a transfer channel and subsequent readout. This paper reports the performances of the charge injection capability based on the ground experiments using a radiation damaged device, and in-orbit measurements of the XIS. The ground experiments show that charges are stably injected with the dispersion of 91eV in FWHM in a specific column for the charges equivalent to the X-ray energy of 5.1keV. This dispersion width is significantly smaller than that of the X-ray events of 113eV (FWHM) at approximately the same energy. The amount of charge loss during transfer in a specific column, which is measured with the charge injection capability, is consistent with that measured with the calibration source. These results indicate that the charge injection technique can accurately measure column-dependent charge losses rather than the calibration sources. The column-to-column CTI correction to the calibration source spectra significantly reduces the line widths compared to those with a column-averaged CTI correction (from 193eV to 173eV in FWHM on an average at the time of one year after the launch). In addition, this method significantly reduces the low energy tail in the line profile of the calibration source spectrum.Comment: Paper contains 18 figures and 15 tables. Accepted for publication in PAS

Mathematical modeling of atopic dermatitis reveals "double switch" mechanisms underlying 4 common disease phenotypes

Background: The skin barrier acts as the first line of defense against constant exposure to biological, microbial, physical and chemical environmental stressors. Dynamic interplay between defects in the skin barrier, dysfunctional immune responses, and environmental stressors are major factors in the development of atopic dermatitis (AD). A systems-biology modeling approach can yield significant insights into these complex and dynamic processes through integration of prior biological data. Objective: To develop a multi-scale mathematical model of AD pathogenesis that describes the dynamic interplay between the skin barrier, environmental stress and immune dysregulation, and use it to achieve a coherent mechanistic understanding of onset, progression and prevention of AD. Methods: We mathematically investigated synergistic effects of known genetic and environmental risk factors on the dynamic onset and progression of the AD phenotype, from a mostly asymptomatic mild phenotype to a severe treatment-resistant form. Results: Our model analysis identified a “double switch”, with two concatenated bistable switches, as a key network motif that dictates AD pathogenesis: The first switch is responsible for the reversible onset of inflammation; The second switch is triggered by long-lasting or frequent activation of the first switch, causing the irreversible onset of systemic Th2 sensitization and worsening of AD symptoms. Conclusions: Our mathematical analysis of the bistable switch predicts that genetic risk factors lower the threshold of environmental stressors to trigger systemic Th2 sensitization. This analysis predicts and explains four common clinical AD phenotypes from a mild and reversible phenotype through to severe and recalcitrant disease and provides a mechanistic explanation for clinically-demonstrated preventive effects of emollient treatments against development of AD

Light hadron spectroscopy in two-flavor QCD with small sea quark masses

We extend the study of the light hadron spectrum and the quark mass in two-flavor QCD to smaller sea quark mass, corresponding to $m_{PS}/m_{V}=0.60$--0.35. Numerical simulations are carried out using the RG-improved gauge action and the meanfield-improved clover quark action at $\beta=1.8$ ($a = 0.2$ fm from $\rho$ meson mass). We observe that the light hadron spectrum for small sea quark mass does not follow the expectation from chiral extrapolations with quadratic functions made from the region of $m_{PS}/m_{V}=0.80$--0.55. Whereas fits with either polynomial or continuum chiral perturbation theory (ChPT) fails, the Wilson ChPT (WChPT) that includes $a^2$ effects associated with explicit chiral symmetry breaking successfully fits the whole data: In particular, WChPT correctly predicts the light quark mass spectrum from simulations for medium heavy quark mass, such as m_{PS}/m_V \simgt 0.5. Reanalyzing the previous data %at $m_{PS}/m_{V}=0.80$--0.55 with the use of WChPT, we find the mean up and down quark mass being smaller than the previous result from quadratic chiral extrapolation by approximately 10%, $m_{ud}^{\bar{\rm MS}}(\mu=2 {GeV}) = 3.11(17)$ [MeV] in the continuum limit.Comment: 33 page

Itinerant ferromagnetism in half-metallic CoS_2

We have investigated electronic and magnetic properties of the pyrite-type CoS_2 using the linearized muffin-tin orbital (LMTO) band method. We have obtained the ferromagnetic ground state with nearly half-metallic nature. The half-metallic stability is studied by using the fixed spin moment method. The non-negligible orbital magnetic moment of Co 3d electrons is obtained as $\mu_L = 0.06 \mu_B$ in the local spin density approximation (LSDA). The calculated ratio of the orbital to spin angular momenta / = 0.15 is consistent with experiment. The effect of the Coulomb correlation between Co 3d electrons is also explored with the LSDA + U method. The Coulomb correlation at Co sites is not so large, $U \lesssim 1$ eV, and so CoS_2 is possibly categorized as an itinerant ferromagnet. It is found that the observed electronic and magnetic behaviors of CoS_2 can be described better by the LSDA than by the LSDA + U.Comment: 4 pages, 3 postscript figure