Iteration Method to Derive Exact Rotation Curves from Position-Velocity Diagrams of Spiral Galaxies

We present an iteration method to derive exact rotation curves (RC) of spiral galaxies from observed position-velocity diagrams (PVD), which comprises the following procedure. An initial rotation curve, RC0, is adopted from an observed PV diagram (PV0), obtained by any simple method such as the peak-intensity method. Using this rotation curve and an observed radial distribution of intensity (emissivity), we construct a simulated PV diagram (PV1). The difference between a rotation curve obtained from this PV1 and the original RC (e.g., difference between peak-intensity velocities) is used to correct the initial RC to obtain a corrected rotation curve, RC1. This RC1 is used to calculated another PVD (PV2) using the observed intensity distribution, and to obtain the second iterated RC (RC2). This iteration is repeated until PV$i$ converges to PV0, so that the differences between PV$i$ and PV0 becomes minimum. Finally RC$i$ is adopted as the most reliable rotation curve. We apply this method to some observed PVDs of nearby galaxies, and show that the iteration successfully converges to give reliable rotation curves. We show that the method is powerful to detect central massive objects.Comment: To appear in ApJ.Letters, 5 pages Latex with 4 figure

Differential regulation of immune responses and macrophage/neuron interactions in the dorsal root ganglion in young and adult rats following nerve injury

Background: Neuropathic pain is an apparently spontaneous experience triggered by abnormal physiology of the peripheral or central nervous system, which evolves with time. Neuropathic pain arising from peripheral nerve injury is characterized by a combination of spontaneous pain, hyperalgesia and allodynia. There is no evidence of this type of pain in human infants or rat pups; brachial plexus avulsion, which causes intense neuropathic pain in adults, is not painful when the injury is sustained at birth. Since infants are capable of nociception from before birth and display both acute and chronic inflammatory pain behaviour from an early neonatal age, it appears that the mechanisms underlying neuropathic pain are differentially regulated over a prolonged postnatal period.Results: We have performed a microarray analysis of the rat L4/L5 dorsal root ganglia (DRG), 7 days post spared nerve injury, a model of neuropathic pain. Genes that are regulated in adult rats displaying neuropathic behaviour were compared to those regulated in young rats (10 days old) that did not show the same neuropathic behaviour. The results show a set of genes, differentially regulated in the adult DRG, that are principally involved in immune system modulation. A functional consequence of this different immune response to injury is that resident macrophages cluster around the large A sensory neuron bodies in the adult DRG seven days post injury, whereas the macrophages in young DRG remain scattered evenly throughout the ganglion, as in controls.Conclusions: The results show, for the first time, a major difference in the neuroimmune response to nerve injury in the dorsal root ganglion of young and adult rats. Differential analysis reveals a new set of immune related genes in the ganglia, that are differentially regulated in adult neuropathic pain, and that are consistent with the selective activation of macrophages around adult, but not young large A sensory neurons post injury. These differences may contribute to the reduced incidence of neuropathic pain in infants

Yield Measurements for ^7Be and ^<10>Be Productions from ^<nat>Cu, ^<nat>Ag and ^<197>Au by Bremsstrahlung Irradiation at E_0=200 MeV(II. Radiochemistry)

The yields of ^7Be and ^Be produced by bremsstrahlung having a maximum energy (E_0) of 200 MeV in ^Cu, ^Ag and ^Au targets were investigated by the AMS technique at MALT of the University of Tokyo. It was found that the yields at E_0 = 200 MeV were much lower than those at E_0 ≧250 MeV, obtained in our previous work. A change in the yields of the fragmentation component in the target-mass dependence was observed at E_0=200 MeV when compared with those at E_0≧250 MeV. However, the ratios of the fragmentation yield of ^Be to that of ^7Be remained unchanged throughout the concerned E_0

Radial Distribution of the Mass-to-Luminosity Ratio in Spiral Galaxies and Massive Dark Cores

We derive radial profiles of the surface-mass-density for 19 spiral galaxies directly from their high-resolution rotation curves. Using the corresponding luminosity profiles, we obtain the radial distribution of the mass-to-luminosity ratios ($M/L$) from the inner bulge ($\sim$ a few 100 pc) to the outer disk ($\geq$ 2-10 kpc) for 11 galaxies (with inclination < $70^{\circ}$ in order to reduce the influence of the interstellar extinction. The $M/L$s in the bulges of two galaxies with sufficient resolution, NGC 4527 and NGC 6946, are found to increase steeply toward the center at radii $\sim$ 100-500 pc at rates of 15$\pm$3 and 7$\pm$2 times per kpc, respectively. Some other galaxies with fairly high resolution also show signs of an increase toward the center. Such an increase may indicate the existence of a new component, a ``massive dark core'', which may be an object linking the bulge and a central black hole. Based on radial variations of the $M/L$, we further discuss the variation of the dark-mass fraction in spiral galaxies.Comment: Latex 19 pages, 30 ps figures. ApJ in pres

Strong neuroprotection with a novel platinum nanoparticle against ischemic stroke- andtissue plasminogen activator-related brain damages in mice

Reactive oxygen species (ROS) are major exacerbation factor in acute ischemic stroke, and thrombolytic agent tissue plasminogen activator (tPA) may worsen motor function and cerebral infarcts. The platinum nanoparticle (nPt) is a novel ROS scavenger, and thus we examined the clinical and neuroprotective effects of nPt in ischemic mouse brains. Mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min and divided into the following four groups by intravenous administration upon reperfusion, vehicle, tPA, tPA + nPt, and nPt. At 48 h after tMCAO, motor function, infarct volume, immunohistochemical analyses of neurovascular unit (NVU), in vivo imaging of matrix metalloproteinase (MMP), and zymography for MMP-9 activity were examined. Superoxide anion generation at 2 h after tMCAO was also examined with hydroethidine (HEt). As a result, administration of tPA deteriorated the motor function and infarct volume as compared to vehicle. In vivo optical imaging of MMP showed strong fluorescent signals in affected regions of tMCAO groups. Immunohistochemical analyses revealed that tMCAO resulted in a minimal decrease of NAGO and occludin, but a great decrease of collagen IV and a remarkable increase of MMP-9. HEt stain showed increased ROS generation by tMCAO. All these results became pronounced with tPA administration, and were greatly reduced by nPt. The present study demonstrates that nPt treatment ameliorates neurological function and brain damage in acute cerebral infarction with neuroprotective effect on NVU and inactivation of MMP-9. The strong reduction of ROS production by nPt could account for these remarkable neurological and neuroprotective effects against ischemic stroke

New southern blue compact dwarf galaxies in the 2dF Galaxy Redshift Survey

Aiming to find new extremely metal-deficient star-forming galaxies we extracted from the Two-Degree Field Galaxy Redshift Survey (2dFGRS) 100K Data Release 14 emission-line galaxies with relatively strong [OIII] 4363 emission. Spectroscopic and photometric studies of this sample and, in addition, of 7 Tololo and 2 UM galaxies were performed on the basis of observations with the ESO 3.6m telescope. All sample galaxies qualify with respect to their photometric and spectroscopic properties as blue compact dwarf (BCD) galaxies. Additionally, they show a good overlap with a comparison sample of 100 well-studied emission-line galaxies on the 12+log(O/H) vs. log(Ne/O), log(Ar/O) and log(Fe/O) planes. From the analysis of the 2dFGRS subsample we report the discovery of two new extremely metal-deficient BCDs with an oxygen abundance 12+log(O/H) < 7.6 and of another seven galaxies with 12+log(O/H) < 7.8. Furthermore, we confirm previous oxygen abundance determinations for the BCDs Tol 1304-353, Tol 2146-391, UM 559 and UM 570 to be 12+log(O/H) < 7.8.Comment: 26 pages, 65 figures, 5 tables, uses psfig.sty, Accepted for publication in Astronomy and Astrophysics. The paper with high-resolution figures can be downloaded at http://www.uni-sw.gwdg.de/~papade/Publications/Papaderos2006_2dF.pd

Measurement of electric field gradient at 117In on the Cu-site in mavicyanin by perturbed angular correlation of γ-rays

金沢大学理工研究域物質化学系The structure around the metal site of mavicyanin, a protein molecule with a copper site, was investigated in solution by using time-differential perturbed angular correlation of 117In. The electric field gradient (EFG) of the metal site was deduced from the measurement. It demonstrated that the site in a mutant-type mavicyanin, Thr15Ala-Mav, gives an EFG different from that in the wild-type mavicyanin does. The pH dependence of the EFG was also observed for both proteins. © 2008 Springer Science+Business Media B.V