Optical Spectra in the Ferromagnetic States near the Charge Ordering

The optical conductivity is studied numerically for the ferromagnetic metallic state close to the charge ordering observed in perovskite manganites.Comment: 11 pages, Latex, 6 ps figure

Stripe orders in the extended Hubbard model

We study stripe orders of charge and spin density waves in the extended Hubbard model with the nearest-neighbor Coulomb repulsion V within the mean field approximation. We obtain V vs. T(temperature) phase diagram for the on-site Coulomb interaction U/t=8.0 and the filling n=0.8, here t is a nearest-neighbor transfer energy. Our result shows that the diagonal stripe spin density wave state (SDW) is stable for small V, but for large V the most stable state changes to a charge density wave-antiferromagnetic (CDW-AF) state. Especially we find at low temperature and for a certain range of value of V, a vertical stripe CDW-AF state becomes stable.Comment: LaTeX 9 pages, 17 figures, uses jpsj.st

Extended Aharonov-Bohm period analysis of strongly correlated electron systems

The `extended Aharonov-Bohm (AB) period' recently proposed by Kusakabe and Aoki [J. Phys. Soc. Jpn (65), 2772 (1996)] is extensively studied numerically for finite size systems of strongly correlated electrons. While the extended AB period is the system length times the flux quantum for noninteracting systems, we have found the existence of the boundary across which the period is halved or another boundary into an even shorter period on the phase diagram for these models. If we compare this result with the phase diagram predicted from the Tomonaga-Luttinger theory, devised for low-energy physics, the halved period (or shorter periods) has a one-to-one correspondence to the existence of the pairing (phase separation or metal-insulator transition) in these models. We have also found for the t-J model that the extended AB period does not change across the integrable-nonintegrable boundary despite the totally different level statistics.Comment: 26 pages, RevTex, 16 figures available on request from [email protected], to be published in J. Phys. Soc. Jpn 66 No. 7(1997), We disscus the extended AB period of strongly correlated systems more systematically by performing numerical calculation for the t-J-J' model and the extended Hubbard model in addition to the 1D t-J model and the t-J ladde

Incidence and Risk Factors for Severity of Postoperative Ileus After Colorectal Surgery: A Prospective Registry Data Analysis

International audienceBackground Defining severe postoperative ileus in terms of consequences could help physicians standardize the management of this condition. The recently described classification based on consequences requires further investigation. The aim of this study was to obtain a snapshot of postoperative ileus in patients undergoing colorectal surgery within enhanced recovery programs and to identify factors associated with non-severe and severe postoperative ileus. Methods This prospective registry data analysis was conducted in 40 centers in five different countries. A total of 786 patients scheduled for colorectal surgery within enhanced recovery programs were included. The primary endpoint was the incidence rate of postoperative ileus as defined by Vather et al. Results A total of 121 patients experienced postoperative ileus (15.4%). Non-severe POI occurred in 48 patients (6.1%), and severe postoperative ileus occurred in 73 patients (9.3%). In multivariate analysis, the male gender and intra-abdominal complications were associated with severe postoperative ileus: odd ratio (OR) = 2.03 [95% confidence interval (CI) 1.14-3.59], p = 0.01 and OR = 3.60 [95% CI 1.75-7.40], p < 0.0001, respectively. Conversely, open laparotomy and urinary retention were associated with non-severe POI: OR = 3.03 [95% CI 1.37-6.72], p = 0.006 and OR = 2.70 [95% CI 0.89-8.23], p = 0.08, respectively. Conclusions Postoperative ileus occurred in 15% of patients after colorectal surgery within enhanced recovery programs. For 60% of patients, this was considered severe. The physiopathology of these two entities could be different, severe POI being linked to intraabdominal complication, while non-severe POI being linked with risk factors for ``primary'' POI. The physician should pay attention to male patients having POI after colorectal surgery and look for features evocating intraabdominal complications