Extended Far-Infrared CO Emission in the Orion OMC-1 Core

We report on sensitive far-infrared observations of $^{12}$CO pure rotational transitions in the OMC-1 core of Orion. The lines were observed with the Long Wavelength Spectrometer (LWS) in the grating mode on board the Infrared Space Observatory (ISO), covering the 43-197 $\mu$m wavelength range. The transitions from $J_{up}=14$ up to $J_{up}=19$ have been identified across the whole OMC-1 core and lines up to $J_{up}= 43$ have been detected towards the central region, KL/IRc2. In addition, we have taken high-quality spectra in the Fabry-Perot mode of some of the CO lines. In KL/IRc2 the lines are satisfactorily accounted for by a three-temperature model describing the plateau and ridge emission. The fluxes detected in the high-$J$ transitions ($J_{up} > 34$) reveal the presence of a very hot and dense gas component ($T=1500-2500$ K; $\rm N(CO)$=2\times 10^{17}\cmmd$), probably originating from some of the embedded sources previously observed in the$\rm H_2$near-infrared lines. At all other positions in the OMC-1 core, we estimate kinetic temperatures$\geq 80$ K and as high as 150 K at some positions around IRc2, from a simple Large-Velocity Gradient model.Comment: 10 pages, 3 figure

Dark matter within high surface brightness spiral galaxies

We present results from a detailed dynamical analysis of five high surface brightness, late type spirals, studied with the aim to quantify the luminous-to-dark matter ratio inside their optical radii. The galaxies' stellar light distribution and gas kinematics have been observed and compared to hydrodynamic gas simulations, which predict the 2D gas dynamics arising in response to empirical gravitational potentials, which are combinations of differing stellar disk and dark halo contributions. The gravitational potential of the stellar disk was derived from near-infrared photometry, color-corrected to constant (M/L); the dark halo was modelled by an isothermal sphere with a core. Hydrodynamic gas simulations were performed for each galaxy for a sequence of five different mass fractions of the stellar disk and for a wide range of spiral pattern speeds. These two parameters mainly determine the modelled gas distribution and kinematics. The agreement between the non-axisymmetric part of the simulated and observed gas kinematics permitted us to conclude that the galaxies with the highest rotation velocities tend to possess near-maximal stellar disks. In less massive galaxies, with v_max<200 km/s, the mass of the dark halo at least equals the stellar mass within 2-3 R_disk. The simulated gas morphology provides a powerful tool to determine the dominant spiral pattern speed. The corotation radius for all galaxies was found to be constant at R_corotation ~ 3 R_disk and encloses the strong part of the stellar spiral in all cases.Comment: 28 pages, 7 figures; to appear in the Astrophysical Journal, Vol. 586, March 200

Development of expression vectors based on pepino mosaic virus

<p>Abstract</p> <p>Background</p> <p>Plant viruses are useful expression vectors because they can mount systemic infections allowing large amounts of recombinant protein to be produced rapidly in differentiated plant tissues. Pepino mosaic virus (PepMV) (genus <it>Potexvirus</it>, family <it>Flexiviridae</it>), a widespread plant virus, is a promising candidate expression vector for plants because of its high level of accumulation in its hosts and the absence of severe infection symptoms. We report here the construction of a stable and efficient expression vector for plants based on PepMV.</p> <p>Results</p> <p>Agroinfectious clones were produced from two different PepMV genotypes (European and Chilean), and these were able to initiate typical PepMV infections. We explored several strategies for vector development including coat protein (CP) replacement, duplication of the CP subgenomic promoter (SGP) and the creation of a fusion protein using the foot-and-mouth disease virus (FMDV) 2A catalytic peptide. We found that CP replacement vectors were unable to move systemically and that vectors with duplicated SGPs (even heterologous SGPs) suffered from significant transgene instability. The fusion protein incorporating the FMDV 2A catalytic peptide gave by far the best results, maintaining stability through serial passages and allowing the accumulation of GFP to 0.2-0.4 g per kg of leaf tissue. The possible use of PepMV as a virus-induced gene silencing vector to study gene function was also demonstrated. Protocols for the use of this vector are described.</p> <p>Conclusions</p> <p>A stable PepMV vector was generated by expressing the transgene as a CP fusion using the sequence encoding the foot-and-mouth disease virus (FMDV) 2A catalytic peptide to separate them. We have generated a novel tool for the expression of recombinant proteins in plants and for the functional analysis of virus and plant genes. Our experiments have also highlighted virus requirements for replication in single cells as well as intercellular and long-distance movement.</p

Migration with local public goods and the gains from changing places

Without public goods and under fairly standard assumptions, in Hammond and Sempere (J Pub Econ Theory, 8: 145–170, 2006) we show that freeing migration enhances the potential Pareto gains from free trade. Here, we present a generalization allowing local public goods subject to congestion. Unlike the standard literature on fiscal externalities, our result relies on fixing both local public goods and congestion levels at their status quo values. This allows constrained efficient and potentially Pareto improving population exchanges regulated only through appropriate residence charges, which can be regarded as Pigouvian congestion taxes

A Dust-Penetrated Classification Scheme for Bars as Inferred from their Gravitational Force Fields

The division of galaxies into ``barred'' (SB) and ``normal'' (S) spirals is a fundamental aspect of the Hubble galaxy classification system. This ``tuning fork'' view was revised by de Vaucouleurs, whose classification volume recognized apparent ``bar strength'' (SA, SAB, SB) as a continuous property of galaxies called the ``family''. However, the SA, SAB, and SB families are purely visual judgments that can have little bearing on the actual bar strength in a given galaxy. Until very recently, published bar judgments were based exclusively on blue light images, where internal extinction or star formation can either mask a bar completely or give the false impression of a bar in a nonbarred galaxy. Near-infrared camera arrays, which principally trace the old stellar populations in both normal and barred galaxies, now facilitate a quantification of bar strength in terms of their gravitational potentials and force fields. In this paper, we show that the maximum value, Qb, of the ratio of the tangential force to the mean radial force is a quantitative measure of the strength of a bar. Qb does not measure bar ellipticity or bar shape, but rather depends on the actual forcing due to the bar embedded in its disk. We show that a wide range of true bar strengths characterizes the category ``SB'', while de Vaucouleurs category ``SAB'' corresponds to a much narrower range of bar strengths. We present Qb values for 36 galaxies, and we incorporate our bar classes into a dust-penetrated classification system for spiral galaxies.Comment: Accepted for publication in the Astrophysical Journal (LaTex, 30 pages + 3 figures); Figs. 1 and 3 are in color and are also available at http://bama.ua.edu/~rbuta/bars

Non-circular motion evidences in the circumnuclear region of M100 (NGC 4321)

We analyse new integral field spectroscopy of the inner region (central 2.5 kpc) of the spiral galaxy NGC 4321 to study the peculiar kinematics of this region. Fourier analysis of the velocity residuals obtained by subtracting an axisymmetric rotation model from the $\rm H\alpha$ velocity field, indicates that the distortions are {\em global} features generated by an $m=2$ perturbation of the gravitational potential which can be explained by the nuclear bar. This bar has been previously observed in the near-infrared but not in the optical continuum dominated by star formation. We detect the optical counterpart of this bar in the 2D distribution of the old stellar population (inferred from the equivalent width map of the stellar absorption lines). We apply the Tremaine--Weinberg method to the stellar velocity field to calculate the pattern speed of the inner bar, obtaining a value of $\Omega_b$=160$\pm70\rm km s^{-1} kpc^{-1}$. This value is considerably la rger than the one obtained when a simple bar model is considered. However the uncertainties in the pattern speed determination prevent us to give support to alternative scenarios.Comment: 11 pages, 11 figures, accepted for publication in MNRA

Tumor de partes blandas en la vecindad de una prótesis de cadera no cementada

Presentamos el caso de un varón de 63 años de edad que fue diagnosticado de un sarcoma de partes blandas en la cara posterior del muslo seis meses después de implantarle una prótesis total de cadera no cementada. Se discute la posible asociación etiológica entre los tumores malignos y el implante de materiales.We present the case of a 63-year-old man who was diagnosed of a soft tissue sarcoma in the posterior side of the thigh six months after a cementless hip replacement. The possible etiological association between malignant tumours and implant materials is discussed

Habitat colonisation by amphipods : comparison between native and alien algae

Invasion of algal habitat by the alien alga Caulerpa racemosa results in changes to habitat structure, part of which may be due to accumulation of large amounts of detritus. In turn, such changes lead to alterations in the assemblage structure of associated invertebrates. The present study was aimed at testing the hypotheses that (i) invasion by C. racemosa will influence the assemblage structure of amphipods associated with vegetated habitats, since colonisation by the invertebrates will differ between native algal habitat and habitat invaded by the alien alga, and (ii) differences in colonisation are mainly due to accumulation of detritus by the alien alga. To test these hypotheses, field experiments on habitat colonisation were undertaken at two sites within each of two Mediterranean localities (Malta and Spain). Using mesh bags, 3 different habitats were introduced at each site: habitat with the native alga Halopteris scoparia, habitat with C. racemosa, and an artificial habitat resembling algal habitat. Additionally, empty mesh bags were deployed as controls. Mesh bags containing plant material were defaunated prior to deployment. For each of the three habitat types, three supplement treatments were used: (i) no detritus, (ii) low detritus, and (ii) high detritus. The bags were placed on a rocky substratum at a water depth of 4.5–5 m for a period of 14 days, after which they were collected and the amphipod assemblage was assessed. The results showed that, overall, amphipod species richness and abundance were higher in bags containing H. scoparia but some amphipods exhibited a broad capability to colonize new habitat such as C. racemosa. Accumulation of detritus by the alien alga may play an important role but small-scale physical or biological habitat features can affect its ecological role.peer-reviewe

Validation of a nowcasting technique from a hydrological perspective

Nowcasting precipitation is a key point to anticipate risks in flood warning systems. In this environment, weather radars are very useful because of the high resolution of their measurements both in time and space. The aim of this study is to assess the performance of a recently proposed nowcasting technique (SPROG) from a hydrological point of view. This technique is based on the advection of radar precipitation fields and its main point is that the forecasted fields get smoothed as the forecasting time increases, to filter out the smallest scales of the field when they become unpredictable. The evaluation of the forecasted precipitation fields is done in two different ways: a) comparing them against the actually measured precipitation fields and b) according to the concept of “hydrological validation”, comparing the hydrographs calculated by a distributed rainfall-runoff model simulating operational conditions (using the forecasted precipitation fields) against the hydrographs calculated by the model with the entire series of radar measurements. This part of the study has been carried out in the framework of the Besos basin flood forecasting system.Postprint (published version