Anomalous behavior of the energy gap in the one-dimensional quantum XY model

We re-examine the well-studied one dimensional spin-1/2 $XY$ model to reveal its nontrivial energy spectrum, in particular the energy gap between the ground state and the first excited state. In the case of the isotropic $XY$ model -- the $XX$ model -- the gap behaves very irregularly as a function of the system size at a second order transition point. This is in stark contrast to the usual power-law decay of the gap and is reminiscent of the similar behavior at the first order phase transition in the infinite-range quantum $XY$ model. The gap also shows nontrivial oscillatory behavior for the phase transitions in the anisotropic model in the incommensurate phase. We observe a close relation between this anomalous behavior of the gap and the correlation functions. These results, those for the isotropic case in particular, are important from the viewpoint of quantum annealing where the efficiency of computation is strongly affected by the size dependence of the energy gap.Comment: 25 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:1501.0292

First-line Combination Strategy Provides Favorable 5-year Outcomes for Patients with Lupus Nephritis: A Single-center Observational Study

This observational study aimed to clarify the long-term results of the combination of mizoribine (MZB), tacrolimus (TAC) and prednisolone as first-line therapy for lupus nephritis (LN). This was our institution’s standard therapy between 2009 and 2015, when we saw 36 patients with LN. When a patient thus treated achieved SLEDAI remission (= 0) and/or the prednisolone dose could be tapered to 5 mg/day, either MZB or TAC was stopped, and the other was continued for maintenance therapy. If treatment failure or relapse occurred, second-line therapy was introduced. At years 1 and 5, overall complete renal response and SLEDAI remission were 94% and 88%, and 50% and 62%, respectively. Excluding 2 cases lost to follow-up, medications after 5 years were as follows: 20 (59%) were stable on 1 drug (MZB or TAC), 11 (32%) required continuation of both drugs (MZB + TAC), and 3 (9%) required second-line therapy. The 5-year retention rate was 91% (non-secondline), with 0% of relapse in this group. Our first-line combination strategy showed high remission rates in the induction phase, and subsequent maintenance therapy demonstrated good outcomes for up to 5 years. Research that fine-tunes the order of therapeutic agents and institutes appropriate treatment goals may further improve long-term outcomes for patients with LN

Frequency ratios of Sr, Yb and Hg based optical lattice clocks and their applications

This article describes the recent progress of optical lattice clocks with neutral strontium ($^{87}$Sr), ytterbium ($^{171}$Yb) and mercury ($^{199}$Hg) atoms. In particular, we present frequency comparison between the clocks locally via an optical frequency comb and between two Sr clocks at remote sites using a phase-stabilized fibre link. We first review cryogenic Sr optical lattice clocks that reduce the room-temperature blackbody radiation shift by two orders of magnitude and serve as a reference in the following clock comparisons. Similar physical properties of Sr and Yb atoms, such as transition wavelengths and vapour pressure, have allowed our development of a compatible clock for both species. A cryogenic Yb clock is evaluated by referencing a Sr clock. We also report on a Hg clock, which shows one order of magnitude less sensitivity to blackbody radiation, while its large nuclear charge makes the clock sensitive to the variation of fine-structure constant. Connecting all three types of clocks by an optical frequency comb, the ratios of the clock frequencies are determined with uncertainties smaller than possible through absolute frequency measurements. Finally, we describe a synchronous frequency comparison between two Sr-based remote clocks over a distance of 15 km between RIKEN and the University of Tokyo, as a step towards relativistic geodesy.Comment: 11 pages, 5 figures, invited review article in Comptes Rendus de Physique 201

Mizoribine, tacrolimus, and corticosteroid combination therapy successfully induces remission in patients with lupus nephritis

Conventional cyclophosphamide-based treatment regimens for lupus nephritis (LN) are still not considered to be optimal. The aim of this study was to evaluate the efficacy and safety of mizoribine, tacrolimus, and corticosteroid combination therapy for LN. We retrospectively evaluated a combination treatment of mizoribine and tacrolimus with corticosteroids as induction therapy in eight newly diagnosed systemic lupus erythematosus (SLE) patients with biopsy-proven LN. All patients were women, and their mean [standard deviation (SD)] age was 48.5 (20) years. All patients (100 %) had positive anti-double-stranded DNA (anti-dsDNA) antibody titers, and four (50.0 %) were nephrotic. Mean (SD) serum creatinine and daily proteinuria levels were 0.72 (0.4) mg/dl (range 0.33-1.55 mg/dl) and 4.56 (2.8) g (range 0.77-8.2 g), respectively. By month 2, significant improvements in the anti-dsDNA antibody titers, levels of proteinuria, serum albumin, and C3, and SLE disease activity index score were observed. By month 6, seven patients (87.5 %) were in complete remission, with normalized levels of both proteinuria and serum creatinine. This pilot study suggests that mizoribine and tacrolimus treatment with corticosteroids is well tolerated and may prove to be an optimal alternative remission-inducing regimen for LN

Frequency Ratio of 199Hg and 87Sr Optical Lattice Clocks beyond the SI Limit

We report on a frequency ratio measurement of a Hg199-based optical lattice clock referencing a Sr87-based clock. Evaluations of lattice light shift, including atomic-motion-dependent shift, enable us to achieve a total systematic uncertainty of 7.2×10−17 for the Hg clock. The frequency ratio is measured to be νHg/νSr=2.629 314 209 898 909 60(22) with a fractional uncertainty of 8.4×10−17, which is smaller than the uncertainty of the realization of the International System of Units (SI) second, i.e., the SI limit.UTokyo Research掲載「水銀・ストロンチウム光格子時計の高精度直接比較に成功」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/highly-precise-comparison-of-mercury-and-strontium-optical-lattice-clocks.htmlUTokyo Research "Highly-precise comparison of mercury and strontium optical lattice clocks" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/highly-precise-comparison-of-mercury-and-strontium-optical-lattice-clocks.htm

Predictive Factors of Rectal Toxicity After Permanent iodine-125 Seed Implantation: Prospective Cohort Study in 2339 Patients

Purpose: To evaluate the incidence and the associated factors of rectal toxicity in patients with prostate cancer undergoing permanent seed implantation (PI) with or without external beam radiation therapy (EBRT) in a nationwide prospective cohort study in Japan (J-POPS) during the first 2 years. Methods and materials: A total of 2,339 subjects were available for the analyses. Rectal toxicity was evaluated using the National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. Results: The 3-year cumulative incidence for grade ≥2 rectal toxicity was 2.88%, 1.76%, and 6.53% in all subjects, PI group and EBRT combination therapy group, respectively. On multivariate analysis, among all subjects, grade ≥2 rectal toxicity was associated with rectal volumes receiving 100% of the prescribed dose (R100; p Conclusions: Rectal toxicity was relatively rare in this study compared with previous reports. For Japanese prostate cancer patients, R100 < 1 mL in both PI and EBRT combination therapy groups and interactive planning in EBRT combination therapy group may be effective in decreasing the incidence of rectal toxicity

Resistivity due to a Domain Wall in Ferromagnetic Metal

The resistivity due to a domain wall in ferromagnetic metallic wire is calculated based on the linear response theory. The interaction between conduction electrons and the wall is expressed in terms of a classical gauge field which is introduced by the local gauge transformation in the electron spin space. It is shown that the wall contributes to the decoherence of electrons and that this quantum correction can dominate over the Boltzmann resisitivity, leading to a decrease of resisitivity by nucleation of a wall. The conductance fluctuation due to the motion of the wall is also investigated. The results are compared with recent experiments.Comment: 9 pages, 3 figure