2,062 research outputs found

    CO map and steep Kennicutt-Schmidt relation in the extended UV disk of M63

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    Results from the UV satellite GALEX revealed large extensions of disks in some nearby spiral galaxies, extending out to 3 to 4 times the isophotal radius, r25. M63 is a remarkable example of a spiral galaxy with one of the most extended UV disks, so it offers the opportunity to search for the molecular gas and characterize the star formation in outer disk regions as revealed by the UV emission. We obtained deep CO(1-0) and CO(2-1) observations on the IRAM 30 m telescope along the major axis of the M63 disk from the center out to the galactocentric radius rgal = 1.6 r25 and over a bright UV region at rgal = 1.36 r25. CO(1-0) is detected all along the M63 major axis out to r25, and CO(2-1) is confined to rgal = 0.68 r25, which may betray lower excitation temperatures in the outer disk. CO(1-0) is also detected in the external bright UV region of M63. The radial profiles of the CO emission and of the Halpha, 24 micron, NUV and FUV star formation tracers and HI taken from the literature show a severe drop with the galactocentric radius, such that beyond r25 they are all absent with the exception of a faint UV emission and HI. The CO emission detection in the external UV region, where the UV flux is higher than the UV flux observed beyond r25, highlights a tight correlation between the CO and UV fluxes, namely the amount of molecular gas and the intensity of star formation. This external UV region is dominated by the atomic gas, suggesting that HI is more likely the precursor of H2 rather than the product of UV photodissociation. A broken power law needs to be invoked to describe the Kennicutt-Schmidt (K-S) relation of M63 from the center of the galaxy out to rgal = 1.36 r25. While all along the major axis out to r25 the K-S relation is almost linear, in the external UV region the SFR regime is highly nonlinear and characterized by a steep K-S relation and very low star formation efficiency.Comment: 12 pages, 8 figures, A&A accepte

    Kinematics of disk galaxies in (proto-)clusters at z=1.5

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    We observed star-forming galaxies at z~1.5 selected from the HyperSuprimeCam Subaru Strategic Program. The galaxies are part of two significant overdensities of [OII] emitters identified via narrow-band imaging and photometric redshifts from grizy photometry. We used VLT/KMOS to carry out Halpha integral field spectroscopy of 46 galaxies in total. Ionized gas maps, star formation rates and velocity fields were derived from the Halpha emission line. We quantified morphological and kinematical asymmetries to test for potential gravitational (e.g. galaxy-galaxy) or hydrodynamical (e.g. ram-pressure) interactions. Halpha emission was detected in 36 targets. 34 of the galaxies are members of two (proto-)clusters at z=1.47, confirming our selection strategy to be highly efficient. By fitting model velocity fields to the observed ones, we determined the intrinsic maximum rotation velocity Vmax of 14 galaxies. Utilizing the luminosity-velocity (Tully-Fisher) relation, we find that these galaxies are more luminous than their local counterparts of similar mass by up to ~4 mag in the rest-frame B-band. In contrast to field galaxies at z<1, the offsets of the z~1.5 (proto-)cluster galaxies from the local Tully-Fisher relation are not correlated with their star formation rates but with the ratio between Vmax and gas velocity dispersion sigma_g. This probably reflects that, as is observed in the field at similar redshifts, fewer disks have settled to purely rotational kinematics and high Vmax/sigma_g ratios. Due to relatively low galaxy velocity dispersions (sigma_v < 400 km/s) of the (proto-)clusters, gravitational interactions likely are more efficient, resulting in higher kinematical asymmetries, than in present-day clusters. (abbr.)Comment: Accepted for publication in A&A. 11 pages, 8 figures, 1 tabl

    High dispersion spectroscopy of two A supergiant systems in the Small Magellanic Cloud with novel properties

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    We present the results of a spectroscopic investigation of two novel variable bright blue stars in the SMC, OGLE004336.91-732637.7 (SMC-SC3) and the periodically occulted star OGLE004633.76-731204.3 (SMC-SC4), whose photometric properties were reported by Mennickent et al. (2010). High-resolution spectra in the optical and far-UV show that both objects are actually A + B type binaries. Three spectra of SMC-SC4 show radial velocity variations, consistent with the photometric period of 184.26 days found in Mennickent et al. 2010. The optical spectra of the metallic lines in both systems show combined absorption and emission components that imply that they are formed in a flattened envelope. A comparison of the radial velocity variations in SMC-SC4 and the separation of the V and R emission components in the Halpha emission profile indicate that this envelope, and probably also the envelope around SMC-SC3, is a circumbinary disk with a characteristic orbital radius some three times the radius of the binary system. The optical spectra of SMC-SC3 and SMC-SC4 show, respectively, HeI emission lines and discrete Blue Absorption Components (BACs) in metallic lines. The high excitations of the HeI lines in the SMC-SC3 spectrum and the complicated variations of FeII emission and absorption components with orbital phase in the spectrum of SMC-SC4 suggests that shocks occur between the winds and various static regions of the stars' co-rotating binary-disk complexes. We suggest that BACs arise from wind shocks from the A star impacting the circumbinary disk and a stream of former wind-efflux from the B star accreting onto the A star. We dub these objects prototype of a small group of Magellanic Cloud wind-interacting A + B binaries.Comment: To be published in MNRA

    Gravitational lensing and dynamics in SL2S\,J02140-0535: Probing the mass out to large radius

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    We aim to probe the mass of SL2S\,J02140-0535, a galaxy group at zz = 0.44 from the Strong Lensing Legacy Survey (SL2S). We combine strong lensing modeling and dynamical constraints. The strong lensing analysis is based on multi-band HST/ACS observations exhibiting strong lensing features that we have followed-up spectroscopically with VLT/FORS2. To constrain the scale radius of an NFW mass profile that cannot be constrained by strong lensing, we propose a new method by taking advantage of the large-scale dynamical information provided by VLT/FORS2 and KECK/LRIS spectroscopy of group members. In constrast to other authors, we show that the observed lensing features in SL2S\,J02140-0535 belong to different background sources: one at zz = 1.7 ±\pm 0.1 produces three images, while the other at zz = 1.023 ±\pm 0.001 has only a single image. Our unimodal NFW mass model reproduces these images very well. It is characterized by a concentration parameter c200c_{200} = 6.0 ±\pm 0.6, which is slightly greater than the value expected from Λ\LambdaCDM simulations for a mass of M200_{200} \approx 1 ×\times 1014^{14} M_{\sun}. The spectroscopic analysis of group members also reveals a unimodal structure that exhibits no evidence of merging. We compare our dynamic mass estimate with an independent weak-lensing based mass estimate finding that both are consistent. Our combined lensing and dynamical analysis of SL2S\,J02140-0535 demonstrates the importance of spectroscopic information in reliably identifying the lensing features. Our findings argue that the system is a relaxed, massive galaxy group where mass is traced by light. This work shows a potentially useful method for constraining large-scale properties inaccessible to strong lensing, such as the scale radius of the NFW profile.Comment: Accepted for publication in A&

    A model structure for weakly horizontally invariant double categories

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    We construct a model structure on the category DblCat\mathrm{DblCat} of double categories and double functors, whose trivial fibrations are the double functors that are surjective on objects, full on horizontal and vertical morphisms, and fully faithful on squares; and whose fibrant objects are the weakly horizontally invariant double categories. We show that the functor H ⁣:2CatDblCat\mathbb H^{\simeq}\colon \mathrm{2Cat}\to \mathrm{DblCat}, a more homotopical version of the usual horizontal embedding H\mathbb H, is right Quillen and homotopically fully faithful when considering Lack's model structure on 2Cat\mathrm{2Cat}. In particular, H\mathbb H^{\simeq} exhibits a levelwise fibrant replacement of H\mathbb H. Moreover, Lack's model structure on 2Cat\mathrm{2Cat} is right-induced along H\mathbb H^{\simeq} from the model structure for weakly horizontally invariant double categories. We also show that this model structure is monoidal with respect to B\"ohm's Gray tensor product. Finally, we prove a Whitehead Theorem characterizing the weak equivalences with fibrant source as the double functors which admit a pseudo inverse up to horizontal pseudo natural equivalence

    School quality, safe schools: an emperical analysis

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    While the vast majority of US public schools are safe, problems exist that not only threaten the teaching and learning environment, but cause substantive problems for educators. Sensing that certain troubling student behaviors can lead to greater problems, schools have implemented many safe school programs and strategies. Unfortunately, these approaches are viewed as "add-ons" by the education community; that is, additional activities and work for them. What is needed is a framework where safe school programs and strategies are fully integrated into the schooling process. Such a framework exists, and the purpose of our paper has been to integrate the safe schools literature with the quality schools literature in developing such a framework. After reviewing the school quality and school safety literature we extracted main concepts from both bodies of research, and led to an overriding proposition. The proposition suggests that safe school activities can be successful if they are part of the larger task of developing and sustaining quality schools. An analysis of school quality and safety data collected by the NEA tentatively confirms our main proposition. We found that school quality is significantly related to school safety. Additional findings suggest that safety varies across schools, middle schools have more problems than either elementary or high schools, and that the effect of school quality on safety does not depend on grade level. Taken as a whole, the effect of school quality on school safety appears to be very robus

    A 2Cat-inspired model structure for double categories

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    We construct a model structure on the category DblCat\mathrm{DblCat} of double categories and double functors. Unlike previous model structures for double categories, it recovers the homotopy theory of 2-categories through the horizontal embedding H ⁣:2CatDblCat\mathbb{H}\colon2\mathrm{Cat}\to\mathrm{DblCat}, which is both left and right Quillen, and homotopically fully faithful. Furthermore, we show that Lack's model structure on 2Cat2\mathrm{Cat} is both left- and right-induced along H\mathbb{H} from our model structure on DblCat\mathrm{DblCat}. In addition, we obtain a 2Cat2\mathrm{Cat}-enrichment of our model structure on DblCat\mathrm{DblCat}, by using a variant of the Gray tensor product. Under certain conditions, we prove a Whitehead theorem, characterizing our weak equivalences as the double functors which admit an inverse pseudo double functor up to horizontal pseudo natural equivalence. This retrieves the Whitehead theorem for 2-categories. Analogous statements hold for the category wkDblCats\mathrm{wkDblCat}_s of weak double categories and strict double functors, whose homotopy theory recovers that of bicategories. Moreover, we show that the full embedding DblCatwkDblCats\mathrm{DblCat}\to\mathrm{wkDblCat}_s is a Quillen equivalence

    Complex cardiac surgery in a high-risk patient with new-onset severe mitral regurgitation and aorta to right ventricular fistula after transcatheter aortic valve implantation: a case report.

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    Transcatheter aortic valve implantation (TAVI) is the procedure of choice for aortic stenosis in high surgical risk patients, but it is no free from complications. A 86-year-old patient with severe aortic stenosis underwent TAVI 3 years ago with an Edwards Sapiens valve by femoral access. In the echocardiography follow-up, an aorta-right ventricular (Ao-RV) fistula was noted with restrictive flow and no significant shunt and it was treated conservatively. Three years after TAVI, the patient underwent cardiac surgery because of worsening heart failure due to a severe degenerative mitral regurgitation with tethering of P2 due to left ventricular remodelling, a posterior jet of severe regurgitation, and left ventricular dilatation. Surgical replacement of the TAVI and aortic root with a bioprosthesis (Medtronic Freestyle) and direct closure of the fistula was performed along with the mitral valve replacement. The patient was discharged with a good clinical result and no evidence of remaining Ao-RV fistula at transthoracic echocardiography. Aorta-right ventricular fistula is a rare entity. Most reported cases arise after rupture of a congenital coronary sinus aneurism, endocarditis, trauma, and aortic valve or aortic root surgery. This is the 10th reported case after TAVI (9 after an Edwards Sapiens TAVI). Non-significant shunt can be treated conservatively but development of heart failure and death are described in significant shunts. Balloon post-dilatation and the absence of surgical calcium debridement inherent to TAVI may theoretically contribute to the development of the fistula. Surgical replacement and closure of the fistula is a therapeutic option for this entity even in high-risk patients

    Fabricación y estudio de películas delgadas conductoras y transparentes de nano-hilos metálicos preparadas por spin coating

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    (Eng) Transparent conductive thin films on glass substrates from metal nano-wires were produced by the spin coating method by varying the speed of rotation between 1000 and 9000 RPM. Morphological and structural properties of the deposited layers were studied by Scanning Electron Microscopy (SEM). The electrical and optical properties were studied as a function of layer thickness by the Van Der Paw method and transmittance measurements in the range between 350 and 800 nm. A correlation between the thickness of the deposited layers and their electrical and optical properties is obtained, showing less sheet resistance to larger thickness while its transmittance decreases. Samples with sheet resistance of about 20 Ω/sq and with average 77% light transmittance at 550 nm were obtained.(Spa) Se fabricaron películas delgadas conductoras y transparentes sobre sustratos de vidrio a partir de nano-hilos metálicos por el método spin coating, variando la velocidad de rotación entre 1000 y 9000 revoluciones por minuto. De las capas depositadas se hizo un estudio de sus propiedades morfológicas y estructurales mediante microscopía electrónica de barrido (SEM). Las propiedades eléctricas y ópticas se estudiaron en función del espesor de las capas mediante el método de Van Der Paw y con medidas de transmitancia en el rango entre 350 y 800 nm. Se encuentra una correlación entre el espesor de las capas depositadas y sus propiedades eléctricas y ópticas, presentando menor resistencia de hoja a mayores espesores a la vez que su transmitancia disminuye. Se obtuvieron muestras con resistencia de hoja alrededor de 20 Ω/sq y transmitancia óptica promedio de 77% a 550 nm
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