Three-loop order approach to flat polymerized membranes.

We derive the three-loop order renormalization group equations that describe the flat phase of polymerized membranes within the modified minimal subtraction scheme, following the pioneering one-loop order computation of Aronovitz and Lubensky [Phys. Rev. Lett. 60, 2634 (1988)10.1103/PhysRevLett.60.2634] and the recent two-loop order one of Coquand, Mouhanna, and Teber [Phys. Rev. E 101, 062104 (2020)2470-004510.1103/PhysRevE.101.062104]. We analyze the fixed points of these equations and compute the associated field anomalous dimension η at three-loop order. Our results display a marked proximity with those obtained using nonperturbative techniques and reexpanded in powers of ε=4-D. Moreover, the three-loop order value that we get for η at the stable fixed point, η=0.8872, in D=2, is compatible with known theoretical results and within the range of accepted numerical values.

Flat phase of polymerized membranes at two-loop order.

We investigate two complementary field-theoretical models describing the flat phase of polymerized-phantom-membranes by means of a two-loop, weak-coupling, perturbative approach performed near the upper critical dimension D_{uc}=4, extending the one-loop computation of Aronovitz and Lubensky [Phys. Rev. Lett. 60, 2634 (1988)PRLTAO0031-900710.1103/PhysRevLett.60.2634]. We derive the renormalization group equations within the modified minimal substraction scheme, then analyze the corrections coming from two-loop with a particular attention paid to the anomalous dimension and the asymptotic infrared properties of the renormalization group flow. We finally compare our results to those provided by nonperturbative techniques used to investigate these two models.

Treatment challenges in pediatric stroke patients.

Aim. In this study we presented our experience of 18 years on the etiology, risk factors, prophylactic and acute treatment, the effect of treatment to recurrence rate of patients with stroke. Methods. The population included 108 patients who had been treated for stroke at Pediatric Neurology Department of Ankara University with the diagnosis of arterial ischemic stroke and sinovenous thrombosis between January 1992 and August 2010. Forty-one girls (38%) and 67 boys (62%) with mean symptom age 3.1 ± 4.04 years, (0-18 years old) were followed up with a mean period of 4.9 ± 3.78 years (0-17 years). Results. 30 patients had no risk factors, 34 patients had only one risk factor and 44 patients had multiple risk factors. Recurrence was seen in three patients. There was no any statistical correlation between the recurrence of stroke and the existence of risk factors (P = .961). Seventeen patients received prophylactic treatment; 2 of them without any risk factors, 3 had one risk factor, 12 patients, who constituted the majority of our patients, had multiple risk factors (P = .024). Conclusion. With this study we showed that the right prophylaxis for right patients reduces the rate of recurrence.

Assessment of citrullinated myelin by 1H-MR spectroscopy in early-onset multiple sclerosis.

BACKGROUND AND PURPOSE: Myelin instability and citrullinated myelin basic protein have been demonstrated in the brains of patients with chronic and fulminating forms of multiple sclerosis (MS). Our aim was to trace citrulline in the brains of patients with early-onset MS by using proton MR spectroscopy ((1)H-MR spectroscopy). MATERIALS AND METHODS: A short-echo single-voxel (1)H-MR spectroscopy by using the point-resolved proton spectroscopy sequence was performed in 27 patients with MS and 23 healthy subjects. Voxels of interest were chronic demyelinating lesions (CDLs, n = 25) and normal-appearing white matter (NAWM, n = 25) on T2-weighted imaging, and when available in patients with MS, enhancing demyelinating lesions (EDLs, n = 8). Frontal white matter (WM) was studied in control subjects. N-acetylaspartate, choline, and myo-inositol (mIns)-creatine (Cr) ratios and the presence of a citrulline peak were noted. RESULTS: Citrulline peaks were more frequently observed in patients with MS than in control subjects (P = .035), located in the NAWM in 8/25 (32%), in CDLs in 7/25 (28%), and in EDLs of 1/8 (12.5%) patients with MS. The presence of citrulline and measured metabolite/Cr ratios was not related to age at imaging, age at disease onset, duration of disease, or number of relapses. There was no significant metabolic difference between the NAWM of patients with MS and the WM of the control subjects. mIns/Cr was significantly greater in CDLs compared with the NAWM of patients with MS and the WM of healthy subjects. CONCLUSIONS: Citrulline was more frequently identified in the brains of patients with early-onset MS than in healthy subjects by (1)H-MR spectroscopy, suggesting an association of increased citrullination of myelin proteins with demyelinating diseases.