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A series of detailed experiments has been conducted in three laboratory plasma devices to measure the dynamo electric field along the equilibrium field line ͑the ␣ effect͒ arising from the correlation between the fluctuating flow velocity and magnetic field. The fluctuating flow velocity is obtained from probe measurement of the fluctuating E؋B drift and electron diamagnetic drift. The three major findings are the following: ͑1͒ The ␣ effect accounts for the dynamo current generation, even in the time dependence through a ''sawtooth'' cycle; ͑2͒ at low collisionality the dynamo is explained primarily by the widely studied pressureless magnetohydrodynamic ͑MHD͒ model, i.e., the fluctuating velocity is dominated by the E؋B drift; ͑3͒ at high collisionality, a new ''diamagnetic dynamo'' is observed, in which the fluctuating velocity is dominated by the electron diamagnetic drift. In addition, direct measurements of the helicity flux indicate that the dynamo activity transports magnetic helicity from one part of the plasma to another, but the total helicity is roughly conserved, verifying Taylor's ͓Phys. Rev. Lett. 33, 1139 ͑1974͒; Rev. Mod. Phys. 58, 741 ͑1986͔͒ conjecture.

The characteristics of low frequency waves in the presence of E x B rotation of a tandem mirror plasma are investigated using the Fraunhofer diffraction method. The observed dispersion relations are in good agreement with those of drift waves including a Doppler shift due to the E x B rotation velocity. The effect of the radial electric field on the drift waves is studied quantitatively by applying a bias voltage to the end plates of the tandem mirror. The fluctuation level is observed to depend on the radial electric field E r . The fluctuation has a maximum value when E r = 0 and decreases with increasing E r , regardless of its sign. The radial confinement time estimated from the particle balance equation decreases as the fluctuation level increases. The dependence of the fluctuation level agrees with that evaluated from the quasi-linear theory of drift wave turbulence.

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D-dimer is a very sensitive indicator of acute venous thrombosis, suggesting that elevations in patients with DAVFs are likely to reflect sinus thrombosis. D-dimer values decreased and nearly normalized in clinically cured patients during a long-term follow-up period, a finding consistent with completion of thrombosis and cure of the disease. To clarify the correlation between DAVF and sinus thrombosis from the aspect of etiology, we should thoroughly check the variation in the concentration of the thrombophilic factors in the patient with chronic sinus occlusion to know the variation in the fistula formation in the further study.

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Fig. 1 Axial (A), coronal (B), and sagittal (C) computed tomography scans with contrast medium showing the destroyed petrous bone, the internal carotid artery and the aneurysm (arrow), which are exposed to the right middle ear, and a massive hematoma in the right middle ear. 578Neurol Med Chir (Tokyo) 50, 578¿580, 2010 AbstractA 60-year-old man presented with a rare case of pseudoaneurysm in the petrous internal carotid artery (ICA) caused by chronic otitis media manifesting as right otorrhagia after the earpick procedure. Computed tomography showed the destroyed petrous bone; the ICA and the aneurysm, which were exposed to the right middle ear; and a massive hematoma in the right middle ear. Right carotid angiography revealed a pseudoaneurysm arising from the ICA coursing through the middle ear. Two weeks later, the right ICA was trapped after external carotid artery-middle cerebral artery bypass surgery using a vein graft. A biopsy specimen was obtained from the middle ear and the histological diagnosis was inflammatory disease. Pseudoaneurysm often causes sudden massive aural bleeding. The appropriate management strategy may be exclusion of the pseudoaneurysm with revascularization to avoid leaving foreign material in the infected middle ear.

A 25-year-old woman presented with complaints of nausea and headache. She had been treated with a ventriculoperitoneal shunt for hydrocephalus when she was 7 months old. Her bilateral optic discs showed moderate atrophy. Right visual acuity allowed only perception of hand movement and left visual acuity was 0.02 (1.2). Computed tomography (CT) showed mild ventricular dilation but no periventricular lucency. Intracranial pressure (ICP) was not high when the shunt valve was punctured. Her visual acuity deteriorated 5 days after the consultation. She was referred again 8 days after the first consultation. The bilateral optic discs were completely pale. Both pupils were dilated on admission, and the bilateral direct light reflexes were absent. The patient could slightly detect only green light stimulus. CT showed moderate enlargement of the ventricle. ICP was 47 cmH 2 O when the shunt valve was punctured. Shuntgraphy showed obstruction of the shunt at the distal end of peritoneal catheter. Emergent total shunt revision was performed. She could detect dark stimulus and the still-dilated left pupil had recovered direct light reflex on the next day. The visual acuity was 0.01 (0.7) on the left 6 months after the operation, although she was blind in the right eye and the bilateral optic discs were completely pale. Visual loss associated with shunt failure remains a major morbidity in shunted congenital hydrocephalus. Early diagnosis and shunt revision may allow visual recovery.