We report the polarization measurement in prompt γ-ray emission of GRB 100826A with the Gamma-Ray Burst Polarimeter (GAP) aboard the small solar power sail demonstrator IKAROS. We detected the firm change of polarization angle (PA) during the prompt emission with 99.9 % (3.5 σ) confidence level, and the average polarization degree (Π) of 27 ± 11 % with 99.4 % (2.9 σ) confidence level. Here the quoted errors are given at 1 σ confidence level for two parameters of interest. The systematic errors have been carefully included in this analysis, unlike any previous reports. Such a high Π can be obtained in several emission models of gamma-ray bursts (GRBs), including synchrotron and photospheric models. However, it is difficult to explain the observed significant change of PA within the framework of axisymmetric jet as considered in many theoretical works. The non-axisymmetric (e.g., patchy) structures of the magnetic fields and/or brightness inside the relativistic jet are therefore required within the observable angular scale of ∼ Γ −1 . Our observation strongly indicates that the polarization measurement is a powerful tool to constrain the GRB production mechanism, and more theoretical works are needed to discuss the data in more details.

We report observations of the dynamic response of micro-fluctuations and turbulent flux to a low-frequency heating power modulation in the Large Helical Device. The responses of heat flux and micro-fluctuation intensity differ from that of the change in temperature gradient. This result violates the local transport model, where turbulence is determined by the local temperature gradient. A new relationship between flux, gradient and turbulence is found. In addition to the temperature gradient, the heating rate is proposed as a new, direct controlling parameter of turbulence to explain the fast response of turbulence against periodic modulation of heating power.

Mutations in Parkin (a ubiquitin protein ligase) are involved in autosomal recessive juvenile parkinsonism, but it is not known how they cause nigral cell death. We examined the effect of Parkin overexpression on cellular levels of oxidative damage, antioxidant defenses, nitric oxide production, and proteasomal enzyme activity. Increasing expression of Parkin by gene transfection in NT-2 and SK-N-MC cells led to increased proteasomal activity, decreased levels of protein carbonyls, 3-nitrotyrosine-containing proteins, and a trend to a reduction in ubiquitinated protein levels. Transfection of these cells with DNA encoding three mutant Parkins associated with autosomal recessive juvenile parkinsonism (Del 3-5, T240R, and Q311X) gave smaller increases in proteasomal activity and led to elevated levels of protein carbonyls and lipid peroxidation. Turnover of the mutant proteins was slower than that of the wild-type protein, and both could be blocked by the proteasome inhibitor, lactacystin. A rise in levels of nitrated proteins and increased levels of NO 2 ؊ /NO 3 ؊ was also observed in cells transfected with mutant Parkins, apparently because of increased levels of neuronal nitricoxide synthase. The presence of mutant Parkin in substantia nigra in juvenile parkinsonism may increase oxidative stress and nitric oxide production, sensitizing cells to death induced by other insults. Parkinson's disease (PD)1 results from degeneration of dopaminergic neurones in the substantia nigra (1). Although most cases appear sporadic and of unknown cause, oxidative stress and apoptosis are associated with disease progression (1). Consistent with this view, increased levels of oxidative damage to DNA, proteins, and lipids and decreased levels of GSH are found in substantia nigra in PD (1-5).Autosomal recessive juvenile parkinsonism (AR-JP), an early onset form of PD, is characterized by loss of tyrosine hydroxylase-immunoreactive neurones in substantia nigra pars compacta and locus ceruleus, usually without Lewy body formation (6). Various mutations (including deletion or point mutations) in the Parkin gene located on chromosome 6 (6q25.2-q27) have been found in AR-JP patients, but no clear correlations exist between types of Parkin mutations and clinical or pathologic features (7-14).Parkin has been identified as a ubiquitin-protein ligase containing 465 amino acids, which consists of a ubiquitin-like (UBL) domain in the N terminus, two ring-finger motifs (termed RING1 and RING2) flanking a Cys-rich domain, named as the in-between RING (IBR) (9, 14). An additional segment is a linker region that connects two regions of UBL and RING1-IBR-RING2 (named as the RING box). Deletional analysis of Parkin revealed that UBL and the linker region are not necessary for association with a specific E2 enzyme. In contrast, the full region of the RING box is necessary for noncovalent association with E2. Therefore, missense mutations in the RING box of Parkin in AR-JP patients have almost completely lost the specific E2-binding activity.2 Thus, ...

OVERVIEW OF THE LARGE HELICAL DEVICE PROJECT. The Large Helical Device (LHD) has successfully started running plasma confinement experiments after a long construction period of eight years. During the construction and machine commissioning phases, a variety of milestones were attained in fusion engineering which successfully led to the first operation, and the first plasma was ignited on 31 March 1998. Two experimental campaigns are planned in 1998. In the first campaign, the magnetic flux mapping clearly demonstrated a nested structure of magnetic surfaces. The first plasma experiments were conducted with second harmonic 84 and 82.6 GHz ECH at a heating power input of 0.35 MW. The magnetic field was set at 1.5 T in these campaigns so as to accumulate operational experience with the superconducting coils. In the second campaign, auxiliary heating with NBI at 3 MW has been carried out. Averaged electron densities of up to 6 × 10 19 m-3 , central temperatures ranging from 1.4 IAEA-F1-CN-69/OV1/4 2 to 1.5 keV and stored energies of up to 0.22 MJ have been attained despite the fact that the impurity level has not yet been minimized. The obtained scarling of energy confinement time has been found to be consistent with the ISS95 scaling law with some enhancement.

This Letter presents the discovery of macroscale electron temperature fluctuations with a long radial correlation length comparable to the plasma minor radius in a toroidal plasma. Their spatiotemporal structure is characterized by a low frequency of ∼1-3  kHz, ballistic radial propagation, a poloidal or toroidal mode number of m/n=1/1 (or 2/1), and an amplitude of ∼2% at maximum. Nonlinear coupling between the long-range fluctuations and the microscopic fluctuations is identified. A change of the amplitude of the long-range fluctuation is transmitted across the plasma radius at the velocity which is of the order of the drift velocity.