Role of pinch in Argon impurity transport in ohmic discharges of Aditya-U Tokamak

We present experimental results of the trace argon impurity puffing in the ohmic plasmas of Aditya-U tokamak performed to study the argon transport behaviour. Argon line emissions in visible and Vacuum Ultra Violet (VUV) spectral ranges arising from the plasma edge and core respectively are measured simultaneously. During the experiments, space resolved brightness profile of Ar1+ line emissions at 472.69 nm (3p44s 2P3/2-3p44p 2D3/2), 473.59 nm (3p44s 4P5/2-3p44p 4P3/2), 476.49 nm (3p44s 2P1/2-3p44p 2P3/2), 480.60 nm (3p44s 4P5/2-3p44p 4P5/2) are recorded using a high resolution visible spectrometer. Also, a VUV spectrometer has been used to simultaneously observe Ar13+ line emission at 18.79 nm (2s22p 2P3/2-2s2p2 2P3/2) and Ar14+ line emission at 22.11 nm (2s2 1S0-2s2p 1P1). The diffusivity and convective velocity of Ar are obtained by comparing the measured radial emissivity profile of Ar1+ emission and the line intensity ratio of Ar13+ and Ar14+ ions, with those simulated using the impurity transport code, STRAHL. Argon diffusivities ~ 12 m2/s and ~ 0.3 m2/s have been observed in the edge (ρ > 0.85) and core region of the Aditya-U, respectively. The diffusivity values both in the edge and core region are found to be higher than the neo-classical values suggesting that the argon impurity transport is mainly anomalous in the Aditya-U tokamak. Also, an inward pinch of ~ 10 m/s mainly driven by Ware pinch is required to match the measured and simulated data. The measured peaked profile of Ar density suggests impurity accumulation in these discharges.

White Matter Lesion Penumbra Shows Abnormalities on Structural and Physiologic MRIs in the Coronary Artery Risk Development in Young Adults Cohort

BACKGROUND AND PURPOSE

White matter lesions are 1 age-related manifestation of cerebrovascular disease, but subthreshold abnormalities have been identified in nonlesional WM. We hypothesized that structural and physiologic MR imaging findings of early cerebrovascular disease can be measured in middle-aged subjects in tissue adjacent to WM lesions, termed "penumbra."

MATERIALS AND METHODS

WM lesions were defined using automated segmentation in 463 subjects, 43-56 years of age, from the Coronary Artery Risk Development in Young Adults (CARDIA) longitudinal observational cohort study. We described 0- to 2-mm and 2- to 4-mm-thick spatially defined penumbral WM tissue ROIs as rings surrounding WM lesions. The remaining WM was defined as distant normal-appearing WM. Mean signal intensities were measured for FLAIR, T1-, and T2-weighted images, and from fractional anisotropy, mean diffusivity, CBF, and vascular reactivity maps. Group comparisons were made using Kruskal-Wallis and pair-wise t tests.

RESULTS

Lesion volumes averaged 0.738 ± 0.842 cm³ (range, 0.005-7.27 cm³). Mean signal intensity for FLAIR, T2, and mean diffusivity was increased, while T1, fractional anisotropy, and CBF were decreased in white matter lesions versus distant normal-appearing WM, with penumbral tissues showing graded intermediate values (corrected P < .001 for all group/parameter comparisons). Vascular reactivity was significantly elevated in white matter lesions and penumbral tissue compared with distant normal-appearing white matter (corrected P ≤ .001).

CONCLUSIONS

Even in relatively healthy 43- to 56-year-old subjects with small white matter lesion burden, structural and functional MR imaging in penumbral tissue reveals significant signal abnormalities versus white matter lesions and other normal WM. Findings suggest that the onset of WM injury starts by middle age and involves substantially more tissue than evident from focal white matter lesions visualized on structural imaging.

Osteogenesis Imperfecta: An Uncommon Association with Non-Communicating Hydrocephalus

Osteogenesis imperfecta (OI) is a generalised disorder of connective tissue presenting with fragile bones, blue sclera and early deafness. Hydrocephalus is usually associated with type 2 OI. Here we present a rare case of noncommunicating hydrocephalus and patent foramen ovale in type 3 OI. DOI: http://dx.doi.org/10.3126/jnps.v33i1.6692 J Nepal Paediatr Soc. 2013;33(1):63-65

An unusual case of anisocoria in a child with bleeding aneurysm of posterior communicating artery and idiopathic thrombocytopenic purpura (ITP)

Background: It can give rise to bleeding episodes in different parts of the body including the central nervous system with various systemic manifestations. Case: An eight-year old female child, diagnosed as a case of chronic ITP for last two years, developed intense headache and vomiting for a few days before admission. This was associated with right sided mid dilated pupil with brisk reaction to light. MRI-angiography showed a bleeding aneurysm of posterior communicating artery. The features of raised intra cranial tension subsided with conservative management but the anisocoria persisted. Conclusion: A bleeding aneurysm can manifest with anisocoria as a sign of partial third cranial nerve palsy. Key words: ITP, children, leaking aneurysm, anisocoria DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5276 Nepal J Ophthalmol 2011; 3(2): 191-192