Identification and geographic distribution of genetic groups of Erysiphe necator in Chilean vineyards

The grapevine powdery mildew, caused by the biotrophic fungus Erysiphe necator, is one of the most important diseases of this crop in Chile. We converted existing single nucleotide polymorphisms in β-tubulin, rDNA intergenic spacer region 1 and eburicol 14-α-demethylase into three cleaved amplified polymorphic sequences (CAPS). These CAPS markers were used for the genetic characterization of Erysiphe necator isolates collected on clusters of Vitis vinifera cv. 'Cabernet Sauvignon' in 23 vineyards across Chile. Among the 105 Chilean isolates analyzed, 103 revealed to belong to genetic group B and 2 to genetic group A. These results correspond to the first report of the presence of genetic groups A and B of E. necator in Chile

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

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

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

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

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

Análisis de imagen para la cuantificación de cambios morfológicos en biomasa granular, inducidos por la presencia de nitrato en reactores EGSB

Cuatro reactores EGSB (R1-R4) fueron operados a velocidades de carga orgánica de 10 kgCOD/(m³.d), tiempos de retención hidráulicos de 3.6 h, velocidades superficiales de 10 m/h y diferentes concentraciones de nitrato a la entrada, 0, 20, 60 y 100 mgN-NO3-/L en R1, R2, R3 and R4, respectivamente. Después de 20 días de operación continua, la biomasa granular fue caracterizada en términos de: (i) morfología por análisis de imagen cuantitativo; (ii) actividad metanogénica específica en presencia de acetato, butirato, propionato, etanol y una mezcla gaseosa de H2CO2; velocidad de sedimentación. El parámetro LfA, definido como el cuociente entre la longitud total de filamentos y el área total proyectada, fue determinado y se observó que es suficientemente sensible para la cuantificación de diferencias morfológicas inducidas por la presencia de nitrato. Aunque el crecimiento de estructuras filamentosas en la superficie de los gránulos fue evidente, no hubo una disminución notable en la velocidad de sedimentación de los gránulos, probablemente porque durante el período de operación los gránulos crecieron en tamaño. En el reactor R4 se observó un mayor washout que en R1, R2 y R3.Fundação para a Ciência e Tecnologia (FCT

Image analysis to quantify morphological changes in granular sludge induced by nitrate in EGSB reactors

Four EGSB reactors (R1 to R4) were operated at an organic loading rate of 10 kgCOD/(m³.d), hydraulic retention time of 3.6 h, upflow velocity of 10 m/h and different influent nitrate concentrations (0, 20, 60 and 100 mgN-NO_3-/L for R1, R2, R3 and R4, respectively. After about 20 days of operation, the granular sludge was characterized for: (i) morphology by quantitative image analysis; (ii) specific methanogenic activity in the presence of acetate, propionate, butyrate, ethanol and H_2/CO_2; (iii) settling velocity. LfA parameter, defined as the ratio of total filaments length to total projected area, was determined and was sensitive to quantify the different surface morphology, induced by nitrate to the granular sludge. Although the growth of filamentous structures was evident, no significant decrease on the settling velocity was observed, most likely because granules grew during the trial period. A higher washout occurred in R4, as compared to R1, R2 and R3.Grant SFRH/BD/3187/2000.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/BD/20325/99

Image analysis as a tool to recognize anaerobic granulation time

Image analysis techniques were used to monitor the development of anaerobic granules into an EGSB reactor fed with a synthetic substrate based on glucose (30-40% COD) and volatile fatty acids (70-60% COD) during 400 days. Two types of objects were recognized and quantified: aggregates and free filaments. The aggregates were classified into five ranges based on the equivalent diameter: smaller than 11.3 mm (residual), between 11.3 and 35.7 mm, between 35.7 and 112.8 mm, between 112.8 and 356.8 mm and larger than 356.8 mm. For each size range the following parameters were measured: projected area, number of aggregates, width, length, perimeter, and convex envelop. For filaments, the measurements were: number of free filaments and total free filament length. Other parameters were calculated based upon this data: average equivalent diameter, percentage in number of aggregates, percentage in total area, fractal dimensions and a shape factor (P2A), based on the perimeter and on the projected area. Besides, a new parameter was defined in terms of the ratio of filament length to total floc area (LfA). It showed to be very sensitive to the changes in the morphology of the developing granules, and, based upon our granule definition, it was used to determine the granulation time (θg) in our system (120 days). The P_2A factor allowed the quantification of aggregates roughness and was much more sensitive than fractal dimensions. The study was complemented with measurements of specific methanogenic activity (SMA) of the granules in presence of acetate, propionate, butyrate, ethanol and a gas mixture of hydrogen/carbon dioxide.Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI/BD/20325/99 , SFRH/BD/3187/2000

Monitoring granular stability in an industrial UASB reactor treating brewery wastewater

An industrial scale UASB reactor treating a brewery wastewater was monitored during several months, in order to assess the usefulness of a morphological parameter relating the filaments length to the projected area of aggregates, LfA, to anticipate washout problems. It was observed that a selective washout of filamentous bacterial forms could explain the decrease of the acetoclastic and hydrogenophilic activity observed in the trial period. This selective washout was predicted by a peak in LfA that occurred just before a steady increase in the effluent VSS values.Grant SFRH/BD/3187/2000.Fundação para a Ciência e a Tecnologia (FCT) – PRAXIS XXI/BD/20325/99

Ultra-stable performance of an underground-based laser interferometer observatory for gravitational waves

In order to detect the rare astrophysical events that generate gravitational wave (GW) radiation, sufficient stability is required for GW antennas to allow long-term observation. In practice, seismic excitation is one of the most common disturbances effecting stable operation of suspended-mirror laser interferometers. A straightforward means to allow more stable operation is therefore to locate the antenna, the ``observatory'', at a ``quiet'' site. A laser interferometer gravitational wave antenna with a baseline length of 20m (LISM) was developed at a site 1000m underground, near Kamioka, Japan. This project was a unique demonstration of a prototype laser interferometer for gravitational wave observation located underground. The extremely stable environment is the prime motivation for going underground. In this paper, the demonstrated ultra-stable operation of the interferometer and a well-maintained antenna sensitivity are reported.Comment: 8 pages, to appear on PR

A New Galactic 6cm Formaldehyde Maser

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