A methodology for attenuation correction based on the minimization of a cost function

Postprint (published version

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

Fluorescence and absorption properties of chromophoric dissolved organic matter (CDOM) in coastal surface waters of the northwestern Mediterranean Sea, influence of the Rhône River

International audienceSeawater samples were collected monthly in surface waters (2 and 5 m depths) of the Bay of Marseilles (northwestern Mediterranean Sea; 5 • 17 30 E, 43 • 14 30 N) during one year from November 2007 to December 2008 and studied for total organic carbon (TOC) as well as chro-mophoric dissolved organic matter (CDOM) optical properties (absorbance and fluorescence). The annual mean value of surface CDOM absorption coefficient at 350 nm [a CDOM (350)] was very low (0.10 ± 0.02 m −1) in comparison to values usually found in coastal waters, and no significant seasonal trend in a CDOM (350) could be determined. By contrast, the spectral slope of CDOM absorption (S CDOM) was significantly higher (0.023 ± 0.003 nm −1) in summer than in fall and winter periods (0.017 ± 0.002 nm −1), reflecting either CDOM photobleaching or production in surface waters during stratified sunny periods. The CDOM fluorescence, assessed through excitation emission matrices (EEMs), was dominated by protein-like component (peak T; 1.30-21.94 QSU) and marine humic-like component (peak M; 0.55-5.82 QSU), while terrestrial humic-like fluores-cence (peak C; 0.34-2.99 QSU) remained very low. This reflected a dominance of relatively fresh material from biological origin within the CDOM fluorescent pool. At the end of summer, surface CDOM fluorescence was very low and strongly blue shifted, reinforcing the hypothesis of CDOM photobleaching. Our results suggested that unusual Rhône Correspondence to: R. Sempéré ([email protected]) River plume eastward intrusion events might reach Mar-seilles Bay within 2-3 days and induce local phytoplank-ton blooms and subsequent fluorescent CDOM production (peaks M and T) without adding terrestrial fluorescence signatures (peaks C and A). Besides Rhône River plumes, mixing events of the entire water column injected relative aged (peaks C and M) CDOM from the bottom into the surface and thus appeared also as an important source of CDOM in surface waters of the Marseilles Bay. Therefore, the assessment of CDOM optical properties, within the hydrological context, pointed out several biotic (in situ biological production , biological production within Rhône River plumes) and abiotic (photobleaching, mixing) factors controlling CDOM transport, production and removal in this highly urbanized coastal area

Food Sovereignty in the city?: A methodological proposal for evaluating food sovereignty in urban settings

Although the possibility of achieving food sovereignty in urban environments is controversial, we believe that food sovereignty is attainable. In this work we propose a methodology for evaluating it, then test that proposal using San Cristóbal de Las Casas as a case study. For this purpose, we used a participatory methodology to construct a system of food-sovereignty indicators for urban settings. After review and validation by participants and a group of experts, that system consisted of 30 indicators. We tested it by using it to survey households in San Cristóbal. We found that the set of 30 indicators is coherent with the principles of food sovereignty, and that it enabled us to reveal the alimentary vulnerability of the city’s families. We hope that the principles that form the basis for the proposed methodology will be applicable when designing instruments for assessing other cities’ levels of food sovereignty.This work was supported by the Consejo Nacional de Ciencia y Tecnología [561556/307908]

Headache of recent onset in adults: a prospective population-based study

One hundred consecutive adult patients with headache of recent onset were prospectively studied. Every patient was examined by craneal CT scan. Their mean age was 46 years (range 17-82). Neurological examination was normal in 80 patients. Organic headache represented 39% of the entire group, and 26% of them had a normal neurological examination. The yield of CT scan in patients with headaches and a normal neurological examination was 22.5% (95% IC: 14%-33%); of which we encountered the following pathologies: intracranial tumors (13), hydrocephalus (2), arachnoid cyst (l), toxoplasmic abscess (1) and parenchymal hemorrhage (1). The clinical characteristics of the headache on their own was insufficient to rule out the possibility of an intracranial tumor. Neuroimaging studies should be performed in all adult patients with non-vascular headache of recent onset, I and previously headache-free individual

The Eastern Arm of M83 Revisited: High-Resolution Mapping of 12CO 1-0 Emission

We have used the Owens Valley Millimeter Array to map 12CO (J=1-0) along a 3.5 kpc segment of M83's eastern spiral arm at resolutions of 6.5"x3.5", 10", and 16". The CO emission in most of this segment lies along the sharp dust lane demarking the inner edge of the spiral arm, but beyond a certain point along the arm the emission shifts downstream from the dust lane to become better aligned with the young stars seen in blue and H-beta images. This morphology resembles that of the western arm of M100. Three possibilities, none of which is wholly satisfactory, are considered to explain the deviation of the CO arm from the dust lane: heating of the CO by UV radiation from young stars, heating by low-energy cosmic rays, and a molecular medium consisting of two (diffuse and dense) components which react differently to the density wave. Regardless, the question of what CO emission traces along this spiral arm is a complicated one. Strong tangential streaming is observed where the arm crosses the kinematic major axis of the galaxy, implying that the shear becomes locally prograde in the arms. Inferred from the streaming is a very high gas surface density of about 230 solar masses/pc**2 and an arm-interarm contrast greater than 2.3 in the part of the arm near the major axis. Using two different criteria, we find that the gas at this location is well above the threshold for gravitational instability -- much more clearly so than in either M51 or M100.Comment: Accepted for publication in ApJ. 25 pages, 5 figures. Manuscript in LaTeX, figures in pdf. Fig 3 in colo

Utilización inadecuada de un servicio de urgencias hospitalario. Una evaluación con criterios explícitos

ResumenFundamentoExiste un crecimiento del número de visitas en los servicios de urgencias hospitalarios (SUH) con una elevada proporción de utilización inapropiada. Los métodos empleados para identificar el uso inadecuado basados en criterios implícitos limitan las comparaciones entre hospitales. El objetivo de este estudio es conocer la proporción de visitas inadecuadas en un SUH y sus factores asociados, utilizando un método objetivo.Material y métodoSe utilizó un instrumento basado en criterios explícitos e independientes del diagnóstico para identificar las visitas inapropiadas en una muestra aleatoria de 1.845 pacientes mayores de 14 años que acudieron a los servicios médicos de un SUH, y se analizaron los factores asociados a la demanda inadecuada.ResultadosLa proporción de urgencias inadecuadas fue del 26,8% (495/1.845). En el análisis bivariante la menor edad, la ausencia de patología asociada, las visitas espontáneas y determinados grupos diagnósticos (enfermedades de la piel, músculo-esqueléticas, mentales y sintamos mal definidos) se asociaron a una mayor proporción de uso inadecuado del SUH. Al ajustar las variables mediante regresión logística, la edad, la patología asociada, las consultas espontáneas y los grupos diagnósticos, mantuvieron la asociación con el uso inadecuado, pero otras variables como el ser mujer y la llegada al SUH fuera del turno de noche también se asociaron a una mayor utilización inadecuada.ConclusionesAl menos la cuarta parte de las visitas realizadas en los servicios médicos de los SUH no requieren atención urgente. La inadecuación de las visitas se asocia a características del paciente y el proceso asistido.SummaryBackgroundSeveral studies have shown a growth in the number of visits to accident and emergency (A&E) hospital departments with a high proportion of inappropriate utilization. Methods to identify improper use based on implicit criteria limit the comparisons between hospitals. The aim of this study is to know the proportion of inappropriate attendance's in an A&E department and their associated factors, using a method with objective criteria.MethodsAn instrument based on diagnosis-independent explicit criteria was used to identify inappropriate visits in a random sample of 1845 14-year-old greater patients attended to A&E medical services, and the factors associated with improper demand were analysed.ResultsThe proportion of inappropriate attendance's was of the 26,8% (495/1.845). The unadjusted analysis show that the smaller age, absence of comorbidity, spontaneous visit and some diagnostic groups (diseases of the skin, muscle-skeletal, mental, and bad defined symptoms) were associated to a greater proportion of improper use. Upon adjusting the variables through logistics regression, the age, associated pathology, the spontaneous attendance's and diagnostic groups, maintained the association with improper use, but other variables as woman gender, and night hours were also associated to inappropriate utilization.ConclusionsAt least the fourth part of the attendance's in the A&E medical services do not require urgent attention. Inappropriate utilization is associated to characteristic of the patient and the attended process

HII regions in spiral galaxies: Size distribution, luminosity function, and new isochrone diagnostics of density wave kinematics

We investigate the relationship of the HII region luminosity function (HII LF) to the HII region size distribution and density wave triggering in grand-design spiral galaxies. We suggest that the differential nebular size distribution is described by a power law of slope ~ -4, with flattening at radii below ~ 130 pc. This contrasts with the conventional exponential description, but it is physically and quantitatively consistent with the typical observed value of -2 for the HII LF slope. We have developed an interactive code that computes spatial isochrones for the evolving loci of spiral density waves in disk galaxies. This allows comparison of the nebular spatial distribution with the spatial isochrones for simple rotation curve parameters. Our comparisons for four grand-design galaxies suggest that the corotation radius r_co coincides with the outer ends of the star-forming arms. This value for r_co yields the best spatial correspondence between the HII regions and the isochrones, and also appears to yield a coincidence between the Inner Lindblad Resonance with the radial onset of star formation in the arms. Thus, we suggest that isochrones offer a new, simple, and effective technique for determining r_co, and thus the spiral pattern speed. However, application of the isochrones also demonstrates that evolution of the nebular population is difficult to spatially isolate in these galaxies.Comment: 15 pp, 8 figs, uses emulateapj. Accepted to A