4,989 research outputs found

    Determination of Frequency and Distribution of Hessian Fly (Diptera: Cecidomyiidae) Biotypes in the Northeastern Soft Wheat Region

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    Fifteen collections of Hessian flies from the northern soft winter wheat region of the United States were used to determine the composition and frequency of biotypes. The wheat cultivars \u27Seneca\u27 (H7Hs), \u27Monon\u27 (H3), \u27Knox 62\u27 (~, H7Hg), and \u27Abe\u27 (Hs) were used as differentials. Biotypes J and L replaced biotype B as the prevalent biotype in Indiana, since wheat cultivars having the Hs and the H6 genes have been grown. Biotype GP, the least virulent of any Hessian fly biotypes, was still present in New York indicating that wheat cuItivars with no genes for resistance are still being grown there. The genetic variability of Hessian fly biotypes that enables them to overcome the resistance in wheat cultivars is discussed

    Densitometry and Thermometry of Starburst Galaxies

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    With a goal toward deriving the physical conditions in external galaxies, we present a survey of formaldehyde (H2CO) and ammonia (NH3) emission and absorption in a sample of starburst galaxies using the Green Bank Telescope. By extending well-established techniques used to derive the spatial density in star formation regions in our own Galaxy, we show how the relative intensity of the 1(10)-1(11) and 2(11)-2(12) K-doublet transitions of H2CO can provide an accurate densitometer for the active star formation environments found in starburst galaxies (c.f. Mangum et al. 2008). Similarly, we employ the well-established technique of using the relative intensities of the (1,1), (2,2), and (4,4) transitions of NH3 to derive the kinetic temperature in starburst galaxies. Our measurements of the kinetic temperature constrained spatial density in our starburst galaxy sample represent the first mean density measurements made toward starburst galaxies. We note a disparity between kinetic temperature measurements derived assuming direct coupling to dust and those derived from our NH3 measurements which points to the absolute need for direct gas kinetic temperature measurements using an appropriate molecular probe. Finally, our spatial density measurements point to a rough constancy to the spatial density (10^{4.5} to 10^{5.5} cm^{-3}) in our starburst galaxy sample. This implies that the Schmidt-Kennicutt relation between L_{IR} and M_{dense}: (1) Is a measure of the dense gas mass reservoir available to form stars, and (2) Is not directly dependent upon a higher average density driving the star formation process in the most luminous starburst galaxies.Comment: 4 pages, to appear in proceedings of The 5th Zermatt ISM Symposiu

    The Role of Diffusive Shock Acceleration on Nonequilibrium Ionization in Supernova Remnant Shocks II: Emitted Spectra

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    We present a grid of nonequilibrium ionization models for the X-ray spectra from supernova remnants undergoing efficient diffusive shock acceleration. The calculation follows the hydrodynamics of the blast wave as well as the time-dependent ionization of the plasma behind the shock. The ionization state is passed to a plasma emissivity code to compute the thermal X-ray emission, which is combined with the emission from nonthermal synchrotron emission to produce a self-consistent model for the thermal and nonthermal emission from cosmic-ray dominated shocks. We show how plasma diagnostics such as the G'-ratio of He-like ions, defined as the ratio of the sum of the intercombination, forbidden, and satellite lines to the resonance line, can vary with acceleration efficiency, and discuss how the thermal X-ray emission, when the time-dependent ionization is not calculated self-consistently with the hydrodynamics, can differ from the thermal X-ray emission from models which do account for the hydrodynamics. Finally we compare the thermal X-ray emission from models which show moderate acceleration (~ 35%) to the thermal X-ray emission from test-particle models.Comment: 17 pages, 12 figures. accepted for publication in the Astrophysical Journa

    Molecular Diagnostics in the Mycosphaerella Leaf Spot Disease Complex of Banana and for Radopholus similis

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    Mycosphaerella leaf spots and nematodes threaten banana cultivation worldwide. The Mycosphaerella disease complex involves three related ascomycetous fungi: Mycosphaerella fijiensis, M. musicola and M. eumusae. The exact distribution of these three species and their disease epidemiology remain unclear, since their symptoms and life cycles are rather similar. Diagnosing these diseases and the respective causal agents is based on the presence of host symptoms and fungal fruiting structures, but is time consuming and not conducive to preventive management. In the present study, we developed rapid and robust species-specific diagnostic tools to detect and quantify M. fijiensis, M. musicola and M. eumusae. Conventional species-specific PCR primers were developed based on the actin gene that detected as little as 100, 1 and 10 pg/µl DNA from, respectively, M. fijiensis, M. musicola and M. eumusae. Furthermore, TaqMan real-time quantitative PCR assays that were developed based on the ß-tubulin gene detected quantities as low as 1 pg/µl DNA of each species from pure cultures and 1.6 pg/µl DNA/mg of M. fijiensis from dry leaf tissue. The efficacy of the tests was validated using naturally infected banana leaves. Similar technology has been used to develop a quantitative PCR assay for the banana burrowing nematode, Radopholus similis, which is currently being validate

    Distorted cyclotron line profile in Cep X-4 as observed by NuSTAR

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    We present spectral analysis of NuSTAR and Swift observations of Cep X-4 during its outburst in 2014. We observed the source once during the peak of the outburst and once during the decay, finding good agreement in the spectral shape between the observations. We describe the continuum using a powerlaw with a Fermi-Dirac cutoff at high energies. Cep X-4 has a very strong cyclotron resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line with a Gaussian optical depth or a pseudo-Lorentzian profile both fail to describe the shape of the CRSF accurately, leaving significant deviations at the red side of the line. We characterize this asymmetry with a second absorption feature around 19 keV. The line energy of the CRSF, which is not influenced by the addition of this feature, shows a small but significant positive luminosity dependence. With luminosities between (1-6)e36 erg/s, Cep X-4 is below the theoretical limit where such a correlation is expected. This behavior is similar to Vela X-1 and we discuss parallels between the two systems.Comment: 6 pages, 4 figure, accepted for publication in ApJ letter

    Recovery of acetoclastic activity in anaerobic granular sludge, monitored by methanogenic activity measurements and image analysis

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    The specific acetoclastic activity (SAA) of anaerobic granular sludge was recovered in a lab scale EGSB reactor. The inoculum presented a very low acetoclastic activity (0.81+/-2.48mg COD-CH4/gVSS.day). Ethanol was fed at a COD concentration of 1.5g/L, as sole organic carbon source to promote the biogas production through the hydrogenophilic pathway. During the operation period the specific methanogenic activity (SMA)1 in the presence of acetate, propionate, butyrate, ethanol and H2/CO2, and the biomass morphology were quantified. The SAA steadily increased as expected by the reactor performance, achieving a value of 183+/-13mg COD-CH4/gVSS.day at day 108. From the SMA results it was suggested that, until day 62, the initial methane production rate was dominated by the hydrogenotrophic population and afterwards, the developed acetoclastic activity started to play a role in the initial methane production from ethanol. Until day 62 the ratio between the filaments length and aggregates projected area (LfA)2 increased due to the breakdown of granules inside the reactor, after that decreased and granules development was simultaneous with the increase of the SAA. Percentage of aggregates in size range 0.1 to 1mm (equivalent diameter) increased until day 40 due to granules fragmentation. When the system achieved a steady state, the aggregates size increased

    Adaptaciones posturales en el plano sagital y posterior de hombres chilenos Hockistas sobre césped de alto rendimiento.

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    Tesis (Licenciado en Kinesiología)RESUMEN: Introducción: La Postura es un tema que ha sido motivo de diversos estudios desde hace muchos años. Mantener una postura determinada, es esencial al momento de realizar una actividad relacionada con la vida diaria, como en la realización de un gesto o actividad deportiva. Respecto a esto último se ha establecido que la práctica repetitiva de una disciplina deportiva por un tiempo prolongado genera adaptaciones posturales en los sujetos en diferentes segmentos corporales y planos anatómicos. Objetivo:El objetivo de este estudio fue describir las principales adaptaciones posturales en deportistas chilenos hombres de alto rendimiento de la especialidad Hockey sobre Césped. Materiales y Métodos:Se realizó una evaluación postural a través del análisis fotográfico de 15 hombres hockistas sobre césped de alto rendimiento y de 15 sujetos hombres no deportistas, ambos grupos pertenecientes a un rango etario de entre 20 y 30 años. Además se cuantificó la angulación de las curvaturas de la columna mediante dos inclinómetros validados. Resultados y Discusión: Los deportistas de alto rendimiento presentaron una tendencia al aumento de la lordosis lumbar y un ascenso del hemicuerpo derecho respecto al izquierdo en comparación con el grupo control. Comparando ambos grupos se estableció que existían diferencias significativas (p<0,05) en la curvatura lumbar y posición de la pelvis en el plano sagital, mientras que en el plano posterior fue significativa la diferencia sólo en la posición de los hombros. Finalmente se observó que existía anteposición de cabeza en ambos grupos, lo que podría significar que tal adaptación postural no es consecuencia de la práctica deportiva sino que podría estar presente en la población en general

    Quantitative image analysis as a diagnostic tool for identifying structural changes during a revival process of anaerobic granular sludge

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    Due to unspecified operational problems, the specific acetoclastic activity (SAA) of the anaerobic granular sludge present in an industrial UASB reactor was considerably damaged (from 250 to less than 10mL CH4@STP/gVSS.d), significantly reducing the biogas production of that industrial unit. The hydrogenotrophic methanogenic activity exhibited a value of 600mL CH4@STP/gVSS.d, the settling velocity was 31.479.8 m/h, the average equivalent diameter was 0.9270.43mm, and about 70% of the VSS were structured in aggregates larger than 1mm. In order to study the recovery of the SAA, this sludge was collected and inoculated in a lab-scale expanded granular sludge blanket (EGSB) reactor. Ethanol was fed as the sole carbon source during a trial period of 106 days. Process monitoring included COD removal efficiency, methane production, and periodic determination of the specific methanogenic activity in the presence of acetate, propionate, butyrate, ethanol and H2/CO2. Quantitative image analysis allowed for information to be obtained on granular fragmentation/erosion and filaments release. During the first operational period, biogas production was mainly due to the hydrogenotrophic activity. However, after 40 days, the SAA steadily increased achieving a maximum value of 183713mL CH4@STP/gVSS.d. The onset of SAA recovery, granules breakdown and filaments release to the bulk occurred simultaneously. Further increase in SAA was accompanied by granular growth. In the last 25 days of operation, the size distribution was stable with more than 80% of projected area of aggregates corresponding to granules larger than 1mm (equivalent diameter). Confocal images from FISH hybridized sections of the granules showed that after SAA recovery, the granules developed an organized structure where an acidogenic/acetogenic external layer was apparent. Granular fragmentation and increase of filaments in the bulk, simultaneously with the increase in the acetoclastic activity are described for the first time and might represent a structural response of granular sludge to promote the optimal substrate uptake at minimal diffusion limitations.Fundação para a Ciência e a Tecnologia (FCT) - Grants SFRH/BD/3187/2000, SFRH/BD/13317/2003, Project POCTI/BIO/37934/2001 Grants SFRH/BD/3187/2000, SFRH/BD/13317/200

    A New Galactic 6cm Formaldehyde Maser

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    We report the detection of a new H2CO maser in the massive star forming region G23.71-0.20 (IRAS 18324-0820), i.e., the fifth region in the Galaxy where H2CO maser emission has been found. The new H2CO maser is located toward a compact HII region, and is coincident in velocity and position with 6.7 GHz methanol masers and with an IR source as revealed by Spitzer/IRAC GLIMPSE data. The coincidence with an IR source and 6.7 GHz methanol masers suggests that the maser is in close proximity to an embedded massive protostar. Thus, the detection of H2CO maser emission toward G23.71-0.20 supports the trend that H2CO 6cm masers trace molecular material very near young massive stellar objects.Comment: Accepted for publication in The Astrophysical Journal Letter
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