ISM gas studies towards the TeV PWN HESS J1825-137 and northern region

HESS J1825-137 is a pulsar wind nebula (PWN) whose TeV emission extends across ~1 deg. Its large asymmetric shape indicates that its progenitor supernova interacted with a molecular cloud located in the north of the PWN as detected by previous CO Galactic survey (e.g Lemiere, Terrier & Djannati-Ata\"i 2006). Here we provide a detailed picture of the ISM towards the region north of HESS J1825-137, with the analysis of the dense molecular gas from our 7mm and 12mm Mopra survey and the more diffuse molecular gas from the Nanten CO(1-0) and GRS $^{13}$CO(1-0) surveys. Our focus is the possible association between HESS J1825-137 and the unidentified TeV source to the north, HESS J1826-130. We report several dense molecular regions whose kinematic distance matched the dispersion measured distance of the pulsar. Among them, the dense molecular gas located at (RA, Dec)=(18.421h,-13.282$^{\circ}$) shows enhanced turbulence and we suggest that the velocity structure in this region may be explained by a cloud-cloud collision scenario. Furthermore, the presence of a H$\alpha$ rim may be the first evidence of the progenitor SNR of the pulsar PSR J1826-1334 as the distance between the H$\alpha$ rim and the TeV source matched with the predicted SNR radius R$_{\text{SNR}}$~120 pc. From our ISM study, we identify a few plausible origins of the HESS J1826-130 emission, including the progenitor SNR of PSR J1826-1334 and the PWN G018.5-0.4 powered by PSR J1826-1256. A deeper TeV study however, is required to fully identify the origin of this mysterious TeV source.Comment: 19 figures, 27 pages, accepted by MNRA

High Spectral and Spatial Resolution Observations of Shocked Molecular Hydrogen at the Galactic Center

The presence of OH (1720 MHz) masers, and the absence of counterparts at 1665/1667 MHz has proved to be a clear diagnostic of shocked molecular gas associated with Galactic supernova remnants. This suggests that shocked molecular gas should be associated with the OH (1720 MHz) masers that have been detected in the circumnuclear disk (CND) and Sgr A East at the Galactic center. In order to test this hypothesis, we observed the H$_2$ 1--0 S(1) and Br $\gamma$ lines using NICMOS on the HST and UNSWIRF on the AAT, near the regions where OH (1720 MHz) masers are detected in the CND and Sgr A East. We present the distribution of H$_2$ in the North and South lobes of the CND and in Sgr A East. H$_2$ emission accompanies almost all of the maser spots detected at the Galactic center. In particular, we find a striking filamentary structure near the Northwest of the CND and evidence that shocked molecular gas is associated with the 70 \kms molecular cloud at the Galactic center. We argue that the emission from the CND could arise in gas heated by the dissipation of the random motion of clumps by collisions or the dissipation of turbulence in a more homogeneous medium. In addition, highly red-shifted gas of up to 140 \kms\ close to the eastern edge of the Sgr A East shell is detected. These observations combined with OH (1720 MHz) results suggest that the H$_2$ gas is shocked and accelerated by the expansion of Sgr A East into the 50 and the 70 \kms cloud and into the lobes of the CND.Comment: 31 pages plus 14 figures, ApJ (in press

HST Paschen alpha and 1.9 micron imaging of Sgr A West

We present HST/NICMOS images at 0.2" resolution of the HI Paschen Alpha (PaA) emission line in a 70" x 90" region of the Galactic center centered on the non-thermal radio source Sgr A*. The majority of the emission arises from ionized gas in the mini-spiral in the central parsec. PaA emission is also seen from 26 stellar sources, presumably early-type stars with mass-loss winds. The new data reveal significant small-scale structure (<1"~0.04pc) in the ionized gas of the mini-spiral; low surface brightness emission features are also seen for the first time. Extinction, estimated from the ratio of observed PaA emission to 6-cm continuum emission, varies from 20 to 50 mag with a median Av=31.1 mag, in excellent agreement with earlier estimates for the stellar sources and indepedent measurements derived using H92alpha recombination line data. Large increases in extinction are seen along the periphery of the ionized gas, suggesting that the ionized gas is partially extincted by dust in the molecular clouds at the outside of the ionized regions. The small-scale, filamentary structures in the ionized gas have a free thermal expansion time of only ~ 3000 yrs; either magnetic fields or mass-loss winds from the hot emission line stars may contain the ionized filaments. For both the ionized gas and the stellar continuum, the centroids of the emission remain within ~+/- 1" from a radius of 2" out to 40", providing further evidence that Sgr A* is indeed at or extremely close to the dynamical center of the Galactic nucleus stellar distribution. The 1.9 micron surface brightness increases inwards to 0.9" and then decreases or levels off closer to Sgr A*, possibly indicating the core radius of the central stellar distribution or depletion of the late-type stars by stellar collisions near the central black hole.Comment: 43 pages, 15 figures, 2 tables; Accepted to ApJ (9/1/03 issue

EuroSpine Task Force on Research: support for spine researchers

In recognition of the value of research to the practice of spine care, Federico Balagué and Ferran Pellisé, at the time President and Secretary for EuroSpine, asked Margareta Nordin to set up a Task Force on Research (TFR) for EuroSpine during summer 2011. The concept was to stimulate and facilitate a research community within the society, through two main functions: (1) distribution of EuroSpine funds to researchers; (2) develop and deliver research training/education courses. What has the EuroSpine TFR accomplished since its inception

The Effects of Arginine Deficiency on Lymphoma Cells

When L5178Y and L1210 mouse lymphosarcoma cells were incubated with rat or beef liver arginase there was up to 100% cell destruction in 24 hours. This was reversed specifically with arginine and partially with arginino-succinic acid, citrulline and ornithine. The concentration of arginine was critical; at 8 μmol/l the cells remained viable and reversible inhibition could be shown; below this level cells died. L5178Y cells were grown in medium containing from 0 to 80 μmol/l arginine for 24 hours then transferred to fresh medium for 24 hours. Viable cell counts and mitotic indices were determined, and cells were pulsed with 3H-thymidine, 3H-uridine, 14C-leucine and 14C-arginine at various times. Thymidine uptake was affected most and preceded parallel changes in viable cell numbers. It was concluded that arginine is required by these cells even in a “resting” state and despite some evidence for their capacity to utilize precursors, the tumour cells underwent rapid and extensive destruction when available arginine was severely depleted

The use and effectiveness of the eLib subject gateways: a preliminary investigation

Internet subject gateways were set up under the Electronic Libraries Programme (eLib) in order to address some of the problems of searching the Internet which have been identified by information professionals, i.e. locating relevant, good quality information. This preliminary study examines the extent to which academics in two universities use three eLib subject gateways (EEVL, OMNI and SOSIG). The results are generally encouraging for the eLib programme, but it is necessary for the gateways to be more effectively promoted. The study also found that academics do not have the same misgivings about the general search engines as the information professionals and seem to use them more readily than the gateways