Voltage dip generator for testing wind turbines connected to electrical networks

This paper describes a new voltage dip generator that allows the shape of the time profile of the voltage generated to be configured. The use of this device as a tool to test the fault ride-through capability of wind turbines connected to the electricity grid can provide some remarkable benefits: First, this system offers the possibility of adapting the main features of the time–voltage profile generated (dip depth, dip duration, the ramp slope during the recovery process after clearing fault, etc.) to the specific requirements set forth by the grid operation codes, in accordance with different network electrical systems standards. Second, another remarkable ability of this system is to provide sinusoidal voltage and current wave forms during the overall testing process without the presence of harmonic components. This is made possible by the absence of electronic converters. Finally, the paper includes results and a discussion on the experimental data obtained with the use of a reduced size laboratory prototype that was constructed to validate the operating features of this new device

How future climatic uncertainty and biotic stressors might influence the sustainability of African vegetable production

The study was conducted to determine whether likely global climatic uncertainty in the future will pose substantive risk to small-scale vegetable producers in Africa, and to consider whether climate change threatens the development and sustainability of improved vegetable horticultural systems in Africa. Annual average air temperature and rainfall totals were assessed over the period 1975-2014 or, where possible, for rainfall for longer periods approaching 100 years; the trends in these data sets were determined through linear regression techniques. Predictions of the likely values of annual average air temperatures in the next 25, 50, 75 and 100 years were made. Considerable variability in trends is reported ranging from extremely fast warming in Tunis, Tunisia contrasting with slight cooling in Bamako, Mali. Annual variability in rainfall was substantive but there were no long-term trends of consequence, even when considered over the last 100 years. Consequently, the sustainability of vegetable production will be threatened mostly by changes in pest (e.g., weeds, insects, fungi, bacteria and viruses) damage to crops in small-scale production systems. A call is made for national governments to give these issues enhanced priority in the distribution of future research and capacity-building resources, as most of these production stressors are under-researched and evident solutions to such problems are not currently available

Seminal magnetic fields from Inflato-electromagnetic Inflation

We extend some previous attempts to explain the origin and evolution of primordial magnetic fields during inflation induced from a 5D vacuum. We show that the usual quantum fluctuations of a generalized 5D electromagnetic field cannot provide us with the desired magnetic seeds. We show that special fields without propagation on the extra non-compact dimension are needed to arrive to appreciable magnetic strengths. We also identify a new magnetic tensor field $B_{ij}$ in this kind of extra dimensional theories. Our results are in very good agreement with observational requirements, in particular from TeV Blazars and CMB radiation limits we obtain that primordial cosmological magnetic fields should be close scale invariance.Comment: Improved version. arXiv admin note: text overlap with arXiv:1007.3891 by other author

Banco de semillas de especies arbóreas en bosques nativos del espinal (Entre Ríos)

El objetivo fue evaluar la composición, densidad y frecuencia de especies arbóreas autóctonas en el banco de semillas del suelo, en diferentes agroecosistemas del Espinal entrerriano. El trabajo se realizó en dos áreas de bosques nativos de Entre Ríos sujetas a cambio en el uso de la tierra. Se definieron 4 tratamientos: Bosque nativo estable sin pastoreo (ESP); Bosque nativo estable con pastoreo (ECP); Renoval (REN) y Agricultura (más de 3 años, AGR), evaluándose el banco de semillas del suelo (BSS) a dos profundidades (0-5cm y 5-10cm). Se aplicó el método de la separación física de semillas e identificación bajo lupa binocular. Vachellia caven (espinillo) constituyó la única especie arbórea presente en el BSS de una de las áreas, con muy bajos valores de frecuencia y densidad relativa, mientras que en el otro sitio no se registraron especies arbóreas en el banco. Los resultados obtenidos permiten inferir un bajo potencial de regeneración del estrato arbóreo del bosque nativo a partir del BSS. Es de esperar que la propagación por vía vegetativa (a partir del sistema radical y tocones) constituya un medio de mayor eficacia que el BSS, para asegurar la regeneración natural de las especies arbóreas dominantes de los bosques nativo

Lunasin and Bowman-Birk Protease Inhibitor Concentrations of Protein Extracts from Enzyme-Assisted Aqueous Extraction of Soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent twostage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin

Evolution of the gulf of Cadiz margin and southwest Portugal contourite depositional system : Tectonic, sedimentary and paleoceanographic implications from IODP expedition 339

Acknowledgments This research used samples and data collected through the Integrated Ocean Drilling Program (IODP). The research was partially supported through the CTM 2008-06399-C04/MAR, CTM 2012-39599-C03, CGL2011-26493, CTM2012-38248, SA263U14, IGCP-619, INQUA 1204 and FWF P25831-N29 Projects. Some data were collected with 94-1090-C03-03 (FADO) and MAR-98-0209 (TASYO) Projects. Research was conducted in the framework of the Continental Margins Research Group of the Royal Holloway University of London, People and the Program (Marie Curie Actions) of the European Union's Seventh Framework Program FP7/2007-2013/ under REA Grant Agreement No. 290201 MEDGATE’. We are very grateful to REPSeOL, TGS–NOPEC, and the CSIC-Institut Jaume Almera (http://geodb.ictja.csic.es) for allowing us to use an unpublished seismic data from the Gulf of Cadiz. We thank J. Aguire (UGR, Spain) for comments and suggestions concerning the Pliocene and Quaternary outcrops, B. van den Berg (USAL) for organizing a thought-provoking field-trip to Cadiz, Spain in November, 2014, M. Ángel Caja, L. García Diego, and J. Tritlla (REPSOL) for provenance and diagenetic analysis of early Pliocene sandstones and debrites, and L.J. Lourens (Utrecht University) for providing us the eccentricity and 200-Kys glacio-eustatic sea-level curves included in the Figure 16. Both Prof. D.A.V. Stow (Heriot-Watt Univ., UK) and F.J. Hernández-Molina (RHUL, UK), as the main co-proponents of the IODP Proposal 644 and the co-chiefs of the IODP Exp. 339, thanks to IODP, Exp. IODP 339 Scientists; JR crew and technicians, as well as all people, institutions and companies involved in making IODP a success since 2003. Finally, we also thank the editor, Gert J. De Lange and the reviewers T. Mulder (Bourdeaux Univ.); D. Van Rooij (Ghent Univ) and J. Duarte (Monash Univ.) for their very positive and helpful feedback and discussions in publishing this research.Peer reviewedPublisher PD

Evidence for early disk-locking among low-mass members of the Orion Nebula Cluster

We present high-resolution spectroscopic observations for 91 PMS stars in ONC with masses in the range 0.10-0.25Msun carried out with the multi-fiber spectrograph FLAMES@ESO. Our aim is to better understand the disk-locking scenario in very low-mass stars. We have derived radial velocities, vsini, and full width at 10% of the Halpha emission peak. Using published measurements of infrared excess as disk tracer, and equivalent width of the NIR CaII line lambda8542, mid-IR difference [3.6]-[8.0]micron derived by Spitzer data, and 10% Halpha width as diagnostic of the level of accretion, we have looked for any correlation between vsini divided by the radius and presence of disk and accretion. Four low-mass stars are SB2 systems. The distribution of rotation periods derived from our vsini measurements is unimodal with a peak of few days. Our is lower than the one expected for a random distribution. We find no evidence for a population of fast rotators close to the break-up velocity. A clear correlation between vsini/R and Delta(Ic-K) has been found. While for stars with no circumstellar disk a spread in the rotation rates is seen, stars with a circumstellar disk show an abrupt drop in their rotation rates by a factor of ~5. On the other hand, only a partial correlation between vsini and accretion is observed when other indicators are used. The X-ray coronal activity level shows no dependence on vsini/R suggesting that all stars are in a saturated regime limit. The critical velocity is probably below our vsini detection limit of 9 km/s. The ONC low-mass stars in our sample at present seem to be not locked, but the clear correlation we find between rotation and IR color excess suggests that they were locked once. In addition, the percentage of accretors seems to scale inversely to the stellar mass.Comment: 16 pages, 2 Tables, 17 figures. Accepted by Astronomy and Astrophysics. Full version of abstract is available in the manuscrip

CDK targets Sae2 to control DNA-end resection and homologous recombination

DNA double-strand breaks (DSBs) are repaired by two principal mechanisms: non-homologous end-joining (NHEJ) and homologous recombination (HR)1. HR is the most accurate DSB repair mechanism but is generally restricted to the S and G2 phases of the cell cycle, when DNA has been replicated and a sister chromatid is available as a repair template2-5. By contrast, NHEJ operates throughout the cell cycle but assumes most importance in G1 (refs 4​, ​6). The choice between repair pathways is governed by cyclin-dependent protein kinases (CDKs)2,3,5,7, with a major site of control being at the level of DSB resection, an event that is necessary for HR but not NHEJ, and which takes place most effectively in S and G2 (refs 2​, ​5). Here we establish that cell-cycle control of DSB resection in Saccharomyces cerevisiae results from the phosphorylation by CDK of an evolutionarily conserved motif in the Sae2 protein. We show that mutating Ser 267 of Sae2 to a non-phosphorylatable residue causes phenotypes comparable to those of a sae2Δ null mutant, including hypersensitivity to camptothecin, defective sporulation, reduced hairpin-induced recombination, severely impaired DNA-end processing and faulty assembly and disassembly of HR factors. Furthermore, a Sae2 mutation that mimics constitutive Ser 267 phosphorylation complements these phenotypes and overcomes the necessity of CDK activity for DSB resection. The Sae2 mutations also cause cell-cycle-stage specific hypersensitivity to DNA damage and affect the balance between HR and NHEJ. These findings therefore provide a mechanistic basis for cell-cycle control of DSB repair and highlight the importance of regulating DSB resection

Disease Progression and Serological Assay Performance in Heritage Breed Pigs following Brucella suis Experimental Challenge as a Model for Naturally Infected Feral Swine

Invasive feral swine (Sus scrofa) are one of the most important wildlife species for disease surveillance in the United States, serving as a reservoir for various diseases of concern for the health of humans and domestic animals. Brucella suis, the causative agent of swine brucellosis, is one such pathogen carried and transmitted by feral swine. Serology assays are the preferred field diagnostic for B. suis infection, as whole blood can be readily collected and antibodies are highly stable. However, serological assays frequently have lower sensitivity and specificity, and few studies have validated serological assays for B. suis in feral swine. We conducted an experimental infection of Ossabaw Island Hogs (a breed re-domesticated from feral animals) as a disease-free proxy for feral swine to (1) improve understanding of bacterial dissemination and antibody response following B. suis infection and (2) evaluate potential changes in the performance of serological diagnostic assays over the course of infection. Animals were inoculated with B. suis and serially euthanized across a 16-week period, with samples collected at the time of euthanasia. The 8% card agglutination test performed best, whereas the fluorescence polarization assay demonstrated no capacity to differentiate true positive from true negative animals. Froma disease surveillance perspective, using the 8%card agglutination test in parallel with either the buffered acidified plate antigen test or the Brucella abortus/suis complement fixation test provided the best performance with the highest probability of a positive assay result. Application of these combinations of diagnostic assays for B. suis surveillance among feral swine would improve understanding of spillover risks at the national level

RETRACTED ARTICLE: Age-dependent Increase in Desmosterol Restores DRM Formation and Membrane-related Functions in Cholesterol-free DHCR24−/− Mice

Cholesterol is a prominent modulator of the integrity and functional activity of physiological membranes and the most abundant sterol in the mammalian brain. DHCR24-knock-out mice lack cholesterol and accumulate desmosterol with age. Here we demonstrate that brain cholesterol deficiency in 3-week-old DHCR24−/− mice was associated with altered membrane composition including disrupted detergent-resistant membrane domain (DRM) structure. Furthermore, membrane-related functions differed extensively in the brains of these mice, resulting in lower plasmin activity, decreased β-secretase activity and diminished Aβ generation. Age-dependent accumulation and integration of desmosterol in brain membranes of 16-week-old DHCR24−/− mice led to the formation of desmosterol-containing DRMs and rescued the observed membrane-related functional deficits. Our data provide evidence that an alternate sterol, desmosterol, can facilitate processes that are normally cholesterol-dependent including formation of DRMs from mouse brain extracts, membrane receptor ligand binding and activation, and regulation of membrane protein proteolytic activity. These data indicate that desmosterol can replace cholesterol in membrane-related functions in the DHCR24−/− mouse