Supergalactic winds driven by multiple superstar clusters

We present two dimensional hydrodynamic calculations of free expanding supergalactic winds, taking into consideration strong radiative cooling. Our main premise is that supergalactic winds are powered by collections of superstar clusters. Every individual superstar cluster is a source of a high metallicity radiative supersonic outflow (paper I, 2003, ApJ, 590, 791). The interaction of winds from neighboring knots of star formation is shown to lead to a collection of stationary oblique shocks and crossing shocks, able to structure the general outflow into a network of dense and cold, kpc long filaments that originate near the base of the outflow. The shocks also lead to extended regions of diffuse soft X-ray emission and furthermore, to channel the outflow with a high degree of collimation into the intergalactic medium.Comment: 10 pages, 5 figures, Accepted for publication in The Astrophysical Journa

Ionized and neutral gas in the peculiar star/cluster complex in NGC 6946

The characteristics of ionized and HI gas in the peculiar star/cluster complex in NGC 6946, obtained with the 6-m telescope (BTA) SAO RAS, the Gemini North telescope, and the Westerbork Synthesis Radio Telescope (WSRT), are presented. The complex is unusual as hosting a super star cluster, the most massive known in an apparently non-interacting giant galaxy. It contains a number of smaller clusters and is bordered by a sharp C-shaped rim. We found that the complex is additionally unusual in having peculiar gas kinematics. The velocity field of the ionized gas reveals a deep oval minimum, ~300 pc in size, centered 7" east of the supercluster. The Vr of the ionized gas in the dip center is 100 km/s lower than in its surroundings, and emission lines within the dip appear to be shock excited. This dip is near the center of an HI hole and a semi-ring of HII regions. The HI (and less certainly, HII) velocity fields reveal expansion, with the velocity reaching ~30 km/s at a distance about 300 pc from the center of expansion, which is near the deep minimum position. The super star cluster is at the western rim of the minimum. The sharp western rim of the whole complex is plausibly a manifestation of a regular dust arc along the complex edge. Different hypotheses about the complex and the Vr depression origins are discussed, including a HVC/dark mini-halo impact, a BCD galaxy merging, and a gas outflow due to release of energy from the supercluster stars.Comment: MN RAS, accepte

Spectrophotometric Observations of Blue Compact Dwarf Galaxies: Mrk 370

We present results from a detailed spectrophotometric analysis of the blue compact dwarf galaxy (BCD) Mrk 370, based on deep UBVRI broad-band and Halpha narrow-band observations, and long-slit and two-dimensional spectroscopy of its brightest knots. The spectroscopic data are used to derive the internal extinction, and to compute metallicities, electronic density and temperature in the knots. By subtracting the contribution of the underlying older stellar population, modeled by an exponential function, removing the contribution from emission lines, and correcting for extinction, we can measure the true colors of the young star-forming knots. We show that the colors obtained this way differ significantly from those derived without the above corrections, and lead to different estimates of the ages and star-forming history of the knots. Using predictions of evolutionary synthesis models, we estimate the ages of both the starburst regions and the underlying stellar component. We found that we can reproduce the colors of all the knots with an instantaneous burst of star formation and the Salpeter initial mass function with an upper mass limit of 100 solar masses. The resulting ages range between 3 and 6 Myrs. The colors of the low surface brightness component are consistent with ages larger than 5 Gyr. The kinematic results suggest ordered motion around the major axis of the galaxy.Comment: 26 pages with 14 figures; accepted for publication in Ap

The Nuclear Starburst in NGC 253

We have obtained long-slit spectra of NGC 253 in the J, H, K, and N bands, broadband images in the J, H, and Ks bands, narrowband images centered at the wavelengths of BrGamma and H2(1,0)S(1), and imaging spectroscopy centered on [NeII](12.8um). We use these data and data from the literature in a comprehensive re-assessment of the starburst in this galaxy. We derive the supernova rate from the strength of the infrared [FeII] lines. We find that most of the H2 infrared luminosity is excited by fluorescence in low density gas. We derive a strong upper limit of ~37,000K for the stars exciting the emission lines. We use velocity-resolved infrared spectra to determine the mass in the starburst region. Most of this mass appears to be locked up in the old, pre-existing stellar population. Using these constraints and others to build an evolutionary synthesis model, we find that the IMF originally derived to fit the starburst in M 82 (similar to a Salpeter IMF) also accounts for the properties of NGC 253. The models indicate that rapid massive star formation has been ongoing for 20-30 million years in NGC 253---that is, it is in a late phase of its starburst. We model the optical emission line spectrum expected from a late phase starburst and demonstrate that it reproduces the observed HII/weak-[OI] LINER characteristics.Comment: 48 pages, 14 figures, uses AASTeX macros, to appear in Ap

The Central Velocity Field in NGC 253 : Possible Indication of a Bar

We have investigated whether motion of gas in a bar-like potential can account for the peculiar but systematic velocity field observed in the nuclear region of the starburst galaxy NGC 253. This unusual velocity field with gradients along both major and minor axes was revealed in a high resolution (1.8^{\arcsec}\times 1.0^{\arcsec}) H92$\alpha$ recombination line observation by Anantharamiah and Goss (1996). A simple logarithmic potential is used to model the bar. Assuming that the bulk of the gas flows along closed and non-intersecting x1 (bar) and x2 (anti-bar) orbits of the bar potential, we have computed the expected velocity field and position-velocity diagrams and compared them with the observations. A comparison of the integrated CO intensity maps with the spatial distribution of the x1 and x2 orbits in the model indicates that the nuclear molecular gas in NGC 253 lies mainly on the x2 orbits. We also find that the velocity field observed in the central 100 pc region in the H92$\alpha$ recombination line is well accounted for by the bar model if most of the ionized gas resides in the inner x2 orbits. However, the model is unable to explain the velocity field on a larger scale of $\sim 500$ pc observed using the OVRO interferometer with a resolution of 5^{\arcsec}\times 3^{\arcsec}. The direction of the observed CO velocity field appears twisted compared to the model. We suggest that this perturbation in the velocity field may be due to an accretion event that could have occurred $10^7$ years ago.Comment: 26 latex pages, 7 figures, accepted in Astrophysical Journa

Male breast cancer: a report of 127 cases at a Moroccan institution

Background: Male breast cancer (MBC) is a rare disease representing less than 1% of all malignancies in men and only 1% of all incident breast cancers. Our study details clinico-pathological features, treatments and prognostic factors in a large Moroccan cohort. Findings: One hundred and twenty-seven patients were collected from 1985 to 2007 at the National Institute of Oncology in Rabat, Morocco. Median age was 62 years and median time for consultation 28 months. The main clinical complaint was a mass beneath the areola in 93, 5% of the cases. Most patients have an advanced disease. Ninety-one percent of tumors were ductal carcinomas. Management consisted especially of radical mastectomy; followed by adjuvant radiotherapy and hormonal therapy with or without chemotherapy. The median of follow-up was 30 months. The evolution has been characterized by local recurrence; in twenty two cases (17% of all patients). Metastasis occurred in 41 cases (32% of all patients). The site of metastasis was the bone in twenty cases; lung in twelve cases; liver in seven case; liver and skin in one case and pleura and skin in one case. Conclusion: Male breast cancer has many similarities to breast cancer in women, but there are distinct features that should be appreciated. Future research for better understanding of this disease at national or international level are needed to improve the management and prognosis of male patients

Gene Transfer Using Micellar Nanovectors Inhibits Choroidal Neovascularization In Vivo

PURPOSE: Age-related macular degeneration caused by choroidal neovascularization (CNV) remains difficult to be treated despite the recent advent of several treatment options. In this study, we investigated the in vivo angiogenic control by intravenous injection of polyion complex (PIC) micelle encapsulating plasmid DNA (pDNA) using a mice CNV model. METHODS: The transfection efficiency of the PIC micelle was investigated using the laser-induced CNV in eight-week-old male C57 BJ/6 mice. Firstly, each mouse received intravenous injection of micelle encapsulating pDNA of Yellow Fluorescent Protein (pYFP) on days 1,3 and 5. The expression of YFP was analyzed using fluorescein microscopy and western blotting analysis. In the next experiments, each mouse received intravenous injection of micelle encapsulating pDNA of soluble Fms-like tyrosine kinase-1 (psFlt-1) 1,3 and 5 days after the induction of CNV and the CNV lesion was analyzed by choroidal flatmounts on day 7. RESULTS: Fluorescein microscopy and western blotting analysis revealed that the expression of YFP was confirmed in the CNV area after injection of the PIC micelle, but the expression was not detected neither in mice that received naked pDNA nor those without CNV. Furthermore, the CNV area in the mice that received intravenous injection of the psFlt-1-encapsulated PIC micelle was significantly reduced by 65% compared to that in control mice (p<0.01). CONCLUSIONS: Transfection of sFlt-1 with the PIC micelle by intravenous injection to mice CNV models showed significant inhibition of CNV. The current results revealed the significant potential of nonviral gene therapy for regulation of CNV using the PIC micelle encapsulating pDNA

Unraveling the role of protein dynamics in dihydrofolate reductase catalysis

Protein dynamics have controversially been proposed to be at the heart of enzyme catalysis, but identification and analysis of dynamical effects in enzyme-catalyzed reactions have proved very challenging. Here, we tackle this question by comparing an enzyme with its heavy (15N, 13C, 2H substituted) counterpart, providing a subtle probe of dynamics. The crucial hydride transfer step of the reaction (the chemical step) occurs more slowly in the heavy enzyme. A combination of experimental results, quantum mechanics/molecular mechanics simulations, and theoretical analyses identify the origins of the observed differences in reactivity. The generally slightly slower reaction in the heavy enzyme reflects differences in environmental coupling to the hydride transfer step. Importantly, the barrier and contribution of quantum tunneling are not affected, indicating no significant role for “promoting motions” in driving tunneling or modulating the barrier. The chemical step is slower in the heavy enzyme because protein motions coupled to the reaction coordinate are slower. The fact that the heavy enzyme is only slightly less active than its light counterpart shows that protein dynamics have a small, but measurable, effect on the chemical reaction rate

Deep Near Infrared Mapping of Young and Old Stars in Blue Compact Dwarf Galaxies

We analyze J, H and Ks near-infrared data for 9 Blue Compact Dwarf (BCD) galaxies, selected from a larger sample that we have already studied in the optical. We present contour maps, surface brightness and color profiles, as well as color maps of the sample galaxies. The morphology of the BCDs in the NIR has been found to be basically the same as in the optical. The inner regions of these systems are dominated by the starburst component. At low surface brightness levels the emission is due to the underlying host galaxy; the latter is characterized by red, radially constant colors and isophotes well fit by ellipses. We derive accurate optical near--infrared host galaxy colors for eight of the sample galaxies; these colors are typical of an evolved stellar population. Interestingly, optical near--infrared color maps reveal the presence of a complex, large-scale absorption pattern in three of the sample galaxies. We study the applicability of the Sersic law to describe the surface brightness profiles of the underlying host galaxy, and find that, because of the limited surface brightness interval over which the fit can be made, the derived Sersic parameters are very sensitive to the selected radial interval and to errors in the sky subtraction. Fitting an exponential model gives generally more stable results, and can provide a useful tool to quantify the structural properties of the host galaxy and compare them with those of other dwarf classes as well as with those of star-forming dwarfs at higher redshifts.Comment: 49 pages, 9 figures, 10 tables, accepted for publication in the Astrophysical Journa

A simple dummy liver assist device prolongs anhepatic survival in a porcine model of total hepatectomy by slight hypothermia

<p>Abstract</p> <p>Background</p> <p>Advances in intensive care support such as therapeutic hypothermia or new liver assist devices have been the mainstay of treatment attempting to bridge the gap from acute liver failure to liver transplantation, but the efficacy of the available devices in reducing mortality has been questioned. To address this issue, the present animal study was aimed to analyze the pure clinical effects of a simple extracorporeal dummy device in an anhepatic porcine model of acute liver failure.</p> <p>Methods</p> <p>Total hepatectomy was performed in ten female pigs followed by standardized intensive care support until death. Five animals (dummy group, n = 5) underwent additional cyclic connection to an extracorporeal dummy device which consisted of a plasma separation unit. The separated undetoxified plasma was completely returned to the pigs circulation without any plasma substitution or exchange in contrast to animals receiving intensive care support alone (control group, n = 5). All physiological parameters such as vital and ventilation parameters were monitored electronically; laboratory values and endotoxin levels were measured every 8 hours.</p> <p>Results</p> <p>Survival of the dummy device group was 74 ± 6 hours in contrast to 53 ± 5 hours of the control group which was statistically significant (p < 0.05). Body temperature 24 hours after hepatectomy was significantly lower (36.5 ± 0.5°C vs. 38.2 ± 0.7°C) in the dummy device group. Significant lower values were measured for blood lactate (1.9 ± 0.2 vs. 2.5 ± 0.5 mM/L) from 16 hours, creatinine (1.5 ± 0.2 vs. 2.0 ± 0.3 mg/dL) from 40 hours and ammonia (273 ± 122 vs. 1345 ± 700 μg/dL) from 48 hours after hepatectomy until death. A significant rise of endotoxin levels indicated the onset of sepsis at time of death in 60% (3/5) of the dummy device group animals surviving beyond 60 hours from hepatectomy.</p> <p>Conclusions</p> <p>Episodes of slight hypothermia induced by cyclic connection to the extracorporeal dummy device produced a significant survival benefit of more than 20 hours through organ protection and hemodynamic stabilisation. Animal studies which focus on a survival benefit generated by liver assist devices should especially address the aspect of slight transient hypothermia by extracorporeal cooling.</p