Strategic management of nitrogen within an organic cropping system using digestate from biogas production of recirculated crop residues

This project investigates strategic management of nitrogen by integrating crop residue management with biogas production. The approach offers potential for diversified farmer income, as food crops, feedstock for biogas and digestate for nutrient cycling are produced simultaneously. This type of diversification provides multifunctional solutions in organic farming, especially in production without access to animal manure. Biogas production from crop residues offers the possibility of reducing both emissions and leaching of nutrients to the surrounding ecosystems, as compared to the case where crop residue is incorporated into the soil for decomposition (Baggs et al. 2000; Velthof et al. 2002). This type of multifunctional cropping system provides solutions that can also help to solve issues on conventional farms, such as N emissions, and can also provide local production of biogas

Fiabilidad diagnóstica comparativa de la mielografía y de la tomografía axial computarizada en la hernia discal lumbar

Un grupo de 137 pacientes con hernia discal lumbar fue estudiado retrospectivamente , contrastando los hallazgos quirúrgicos con los proporcionado s por la mielografía y la tomografía axial computarizada (TAC), con objeto de comparar la fiabilidad de ambas técnicas de diagnóstico. La hernia discal correspondió al nivel L5-S1 en 76 pacientes y al L4-L5 en 61. Preoperatoriamente se había efectuado una TAC lumbar en 99 paciente s y una mielografía en 77. En 39 casos se efectuaron ambas exploraciones. La fiabilidad diagnóstica cuantificada por el porcentaje de resultados "verdaderos positivos" fue similar en ambas exploraciones, elevándose al 89% y 90% para la TAC y la mielografía respectivamente . De los 39 paciente s a quiene s se le s practicó ambas exploraciones, en 12 (39%) de ellos no existía concordancia en el diagnóstico. No se registraron "falsos negativos" con la TAC. Como conclusión, ambas técnicas diagnósticas tienen una alta y similar fiabilidad para detectar hernias discale s a nivel lumbar. No obstante, las ventajas que aporta la TAC respecto a la mielografía en cuanto a confort para el pacient e y ausencia de reaccione s adversas hac e que esta técnica sea considerada como el método diagnóstico de elección. La mielografía queda relegada a casos con imágene s dudosas con la TAC.In orde r to compar e the diagnosti c accurac y of CT sca n and myelo - graphy, a series of 137 patients with herniated lumbar disc was retrospectively analyzed matching the surgical findings with the images obtained by both diagnostic techniques. Ther e wer e 7 6 herniate d disc s a t th e L5-S1 leve l an d 6 1 a t th e L4-L5. Preoperatively, 99 patients wer e assessed by CT scan and 77 by mielography. In 39 cases, both technique s wer e performed. The diagnosti c accuracy, quantified by the percentage of "true positive" results wa s similar in both techniques: 89% in CT scan and 90% in mielography . In 12 of the 39 patients explore d by bot h CT scan and myelo - graphy, the results wer e discordant. "False negative" case s wer e not found using CT scan. In conclusion, both CT scan and myelography provide equal high diagnosti c accuracy for lumbar herniated disc. However, CT scan has become the primary diagnostic tool because of several advantages, such as the confort for the patients and the lack of adverse reactions

Effects of bioaugmentation by an anaerobic lipolytic bacterium on anaerobic digestion of lipid-rich waste

The effect of bioaugmentation with an anaerobic lipolytic bacterial strain on the anaerobic digestion of restaurant lipid-rich waste was studied in batch experiments with a model waste containing 10% lipids (triolein) under two sets of experimental conditions: (A) methanogenic conditions, and (B) initially acidogenic conditions in the presence of only the lipolytic strain biomass (4 days), followed by methanogenic conditions. The bioaugmenting lipolytic strain, Clostridium lundense (DSM 17049T), was isolated from bovine rumen. The highest lipolytic activity was detected at the beginning of the experiments. A higher methane production rate, 27.7 cm3 CH4(STP) g-1 VSadded day-1 (VS, volatile solids) was observed in experiment A with the presence of the bioaugmenting lipolytic strain under methanogenic conditions. The highest initial oleate concentration, 99% of the total oleate contained in the substrate, was observed in the experiments with the bioaugmenting lipolytic strain under treatment A conditions; the levels of palmitate and stearate were also higher until day 15, indicating that the bioaugmentation strategy improved the hydrolysis of the lipid fraction. In general, the results indicated that degradation of the long chain fatty acids (LCFAs) controlled the digestion process.Swedish Energy Agency ; Fundação para a Ciência e a Tecnologia (FCT

Surface elevation change and mass balance of Icelandic ice caps derived from swath mode CryoSat-2 altimetry

We apply swath processing to CryoSat-2 interferometric mode data acquired over the Icelandic ice caps to generate maps of rates of surface elevation change at 0.5 km postings. This high-resolution mapping reveals complex surface elevation changes in the region, related to climate, ice dynamics, and subglacial geothermal and magmatic processes. We estimate rates of volume and mass change independently for the six major Icelandic ice caps, 90% of Iceland's permanent ice cover, for five glaciological years between October 2010 and September 2015. Annual mass balance is highly variable; during the 2014/2015 glaciological year, the Vatnajökull ice cap (~70% of the glaciated area) experienced positive mass balance for the first time since 1992/1993. Our results indicate that between glaciological years 2010/2011and 2014/2015 Icelandic ice caps have lost 5.8 ± 0.7 Gt a−1 on average, ~40% less than the preceding 15 years, contributing 0.016 ± 0.002 mm a−1 to sea level rise

Performance of a sisal fibre fixed-bed anaerobic digester for biogas production from sisal pulp waste

A single stage anaerobic digester employing a sisal fibre waste fixed bed was studied for biogas production from sisal pulp waste. The fibre was colonized by microorganisms involved in biogas production. The sisal pulp waste to be digested was fed from the top and was sprinkled intermittently with recirculating leachate from the material. Organic loading rates of 0.1-10 kg volatile solids (VS) m-3d-1 could be applied and methane yields in the range of 0.13-0.48 m3 CH4 kg-1 VS added were obtained. The average methane content in the biogas produced from sisal pulp waste was 55%, and the biogas production rate was 0.15-0.54 m3m-3d-1. The methane yield obtained and the highest organic loading rate that could be sustained by this simple, fixed-bed digester are indications of an attractive system in terms of performance and reliability. It is concluded that the sisal fibre waste fixed bed is a promising carrier for microbes and can be employed for long-term operation without changing the bed. Tanzania Journal of Science Vol. 31 (2) 2005: pp. 41-5

Influence of lipid concentration on the hydrolysis and biomethanation of lipid rich wastes

The influence of lipid concentration on hydrolysis and biomethanation of an artificial lipid rich (triolein) waste was evaluated. No inhibition on methane production was observed for tests with 5, 10 and 18 % (w/w, based on COD) of lipid. For higher amounts of lipid (31, 40 and 47 %) inhibition was observed. However, the process was able to recover from the inhibition. When the effect of lipase addition on enzymatic hydrolysis of lipids was studied, results showed that the higher the enzyme concentration, the more accentuated was the inhibition of the methane production. The enzyme seems to enhance the hydrolysis and produced intermediates are causing inhibition of the later steps of the degradation process. Since the VFA profiles presented similar trends for the different lipid amounts tested, the major obstacle to methane production is believed to be the LCFA formed.Fundação para a Ciência e a Tecnologia (FCT).The Swedish Energy Agency

Anaerobic digestion of lipid-rich waste : effects of lipid concentration

The influence of lipid concentration on hydrolysis and biomethanation of a lipid-rich (triolein) model waste was evaluated in batch. The effect of increasing the concentration of lipid from 5% to 47% (w/w), based on chemical oxygen demand (COD), was investigated. The methane recovery observed was above 93% for all tests. An initial lag phase of approximately 6–10 days was observed for all tests. The methane production rate observed was similar for tests with 5%, 10% and 18% lipid (w/w, COD basis). For higher amounts of lipid (31%, 40% and 47%), a stronger inhibition was observed. However, the process was able to recover from the inhibition. When the effect of addition of lipase on enzymatic hydrolysis of lipids was studied, the results showed that the higher the enzyme concentration, the more accentuated was the inhibition of methane production. The enzyme appears to enhance the hydrolysis but the intermediates produced caused inhibition of the later steps in the degradation process. Since the volatile fatty acid (VFA) profiles presented similar trends for the different concentrations of lipid tested, the major obstacle to methane production was the long-chain fatty acids (LCFA) formation.Swedish Energy AgencyFundação para a Ciência e a Tecnologia (FCT

The Jet and the Supernova in GRB990712

The optical light curve of the afterglow following the gamma-ray burst GRB990712 is re-examined. Recently published polarization measurements of that source require a collimated outflow geometry that in turn predicts a break in the light curve. We show that the V-band light curve is consistent with such a break and that the post-break light curve evolution is dominated by a supernova contribution

Polarization in the inner region of Pulsar Wind Nebulae

We present here the first effort to compute synthetic synchrotron polarization maps of Pulsar Wind Nebulae (PWNe). Our goal is to highlight how polarization can be used as an additional diagnostic tool for the flow structure in the inner regions of these nebulae. Recent numerical simulations suggest the presence of flow velocities ~0.5 c in the surroundings of the termination shock, where most of the high energy emission comes from. We construct polarization maps taking into account relativistic effects like Doppler boosting and position angle swing. The effect of different bulk velocities is clarified with the help of a toy-model consisting of a uniformly emitting torus. We also present a map based on recent numerical simulations of the entire nebula and compare it with presently available data. The comparison with upcoming high resolution observations could provide new insight into the inner structure of the nebula and put constraints on the geometrical properties of the magnetic field.Comment: Accepted for publication on A&A, 6 pages, 2 figure