Exact Dynamics of the SU(K) Haldane-Shastry Model

The dynamical structure factor $S(q,\omega)$ of the SU(K) (K=2,3,4) Haldane-Shastry model is derived exactly at zero temperature for arbitrary size of the system. The result is interpreted in terms of free quasi-particles which are generalization of spinons in the SU(2) case; the excited states relevant to $S(q,\omega)$ consist of K quasi-particles each of which is characterized by a set of K-1 quantum numbers. Near the boundaries of the region where $S(q,\omega)$ is nonzero, $S(q,\omega)$ shows the power-law singularity. It is found that the divergent singularity occurs only in the lowest edges starting from $(q,\omega) = (0,0)$ toward positive and negative q. The analytic result is checked numerically for finite systems via exact diagonalization and recursion methods.Comment: 35 pages, 3 figures, youngtab.sty (version 1.1

Synchronization of Excitatory Neurons with Strongly Heterogeneous Phase Responses

In many real-world oscillator systems, the phase response curves are highly heterogeneous. However, dynamics of heterogeneous oscillator networks has not been seriously addressed. We propose a theoretical framework to analyze such a system by dealing explicitly with the heterogeneous phase response curves. We develop a novel method to solve the self-consistent equations for order parameters by using formal complex-valued phase variables, and apply our theory to networks of in vitro cortical neurons. We find a novel state transition that is not observed in previous oscillator network models.Comment: 4 pages, 3 figure

Exact spin dynamics of the 1/r^2 supersymmetric t-J model in a magnetic field

The dynamical spin structure factor S^{zz}(Q,omega) in the small momentum region is derived analytically for the one-dimensional supersymmetric t-J model with 1/r^2 interaction. Strong spin-charge separation is found in the spin dynamics. The structure factor S^{zz}(Q,omega) with a given spin polarization does not depend on the electron density in the small momentum region. In the thermodynamic limit, only two spinons and one antispinon (magnon) contribute to S^{zz}(Q,omega). These results are derived via solution of the SU(2,1) Sutherland model in the strong coupling limit.Comment: 20 pages, 8 figures. Accepted for publication in J.Phys.

Electron Addition Spectrum in the Supersymmetric t-J Model with Inverse-Square Interaction

The electron addition spectrum A^+(k,omega) is obtained analytically for the one-dimensional (1D) supersymmetric t-J model with 1/r^2 interaction. The result is obtained first for a small-sized system and its validity is checked against the numerical calculation. Then the general expression is found which is valid for arbitrary size of the system. The thermodynamic limit of A^+(k,omega) has a simple analytic form with contributions from one spinon, one holon and one antiholon all of which obey fractional statistics. The upper edge of A^+(k,omega) in the (k,omega) plane includes a delta-function peak which reduces to that of the single-electron band in the low-density limit.Comment: 5 pages, 1 figure, accepted for publication in Phys. Rev. Let

The Usefulness of CT-Diffusion Weighted Image Mismatch in Patients with Mild to Moderate Traumatic Brain Injury

Traumatic brain injury (TBI) has a complex and heterogeneous pathology. It is frequently difficult to predict the neurological deterioration of patients with TBI, and unpredictable change may occur even when TBI is mild to moderate. When computed tomography (CT) findings are considered to be inconsistent with the traumatic origin or with the neurological deterioration of patients observed on admission, magnetic resonance imaging (MRI) is employed based on the standards of our ethical committee. In this retrospective study, we compared CT and diffusion weighted imaging (DWI) of patients with mild to moderate TBI in the very acute phase. When the high-intensity lesions on DWI are larger than the high-density lesions on CT images, we defined the imaging finding as a ʻCT-DWI mismatchʼ. Between January 2010 and December 2013, 92 patients were inspected using both CT and MRI at admission, and we detected a CT-DWI mismatch in 35 patients. CT-DWI mismatch was 92.6 (95 confidence interval 79.8-97.9) sensitive and 84.6 (95 confidence interval 79.3-86.3) specific for the prediction of enlargement of the hemorrhagic lesions on repeat CT. CT-DWI mismatch is considered to be useful as one of the predictors of the enlargement of hemorrhagic lesions in patients with mild to moderate TBI

イ ジョウコウ ケッチョウ チョクチョウ ノ 3 チョウフクガン ニ タイシテ イッキテキ ニ フククウキョウカ シュジュツ オ シコウ シタ 1レイ

A ５１-years-old man was admitted with anemia. The upper gastrointestinal endoscopy revealed ０-IIa＋IIc lesion in the middle body of the stomach. The colonoscopy revealed type ３ lesion by Borrmann classification with advanced stenosis. Computed tomography of the abdomen revealed the tumor in the ascending colon. We diagnosed a synchronous gastric, ascending colon, and rectal cancer. After neoadjuvant chemotherapy, we performed the laparoscopic operation for the synchronous cancer. There were no remarkable complications due to the collaboration. Laparoscopic approach for synchronous triple cancer is feasible as safety and minimally invasive surgery

Exact dynamical structure factor of the degenerate Haldane-Shastry model

The dynamical structure factor $S(q,\omega)$ of the K-component (K = 2,3,4) spin chain with the 1/r^2 exchange is derived exactly at zero temperature for arbitrary size of the system. The result is interpreted in terms of a free quasi-particle picture which is generalization of the spinon picture in the SU(2) case; the excited states consist of K quasi-particles each of which is characterized by a set of K-1 quantum numbers. Divergent singularities of $S(q,\omega)$ at the spectral edges are derived analytically. The analytic result is checked numerically for finite systems.Comment: 4 pages, 1 figure, accepted for publication in Phys. Rev. Let