675 research outputs found
Greenhouse and field techniques for testing sugar beet for resistance to Rhizoctonia root and crown rot
No full textRhizoctonia-resistant sugar beet varieties are the key to an integrated control strategy for Rhizoctonia root rot. Because of the unpredictable occurrence of Rhizoctonia solani in the field testing of sugar beet for resistance to Rhizoctonia root rot is difficult. The aim of the study was to develop advanced greenhouse and field techniques which allow a reliable assessment of sugar beet for resistance to R. solani. A highly infectious liquid inoculum was used for the first time in this study. It can be produced in large quantities of a standardized quality, sterile, and exactly quantified according to its carbon content. In a greenhouse trial, sugar beet grown in the same way as field grown beet was inoculated by applying a suspension of Rhizoctonia mycelium (equivalent to 10 mg carbon per plant) to the beet crown. After 3 weeks, inoculation had led to uniform and severe root rot. Disease symptoms were similar to those found under natural conditions in the field. No 'escapes', i.e. susceptible plants apparently expressing resistance were observed in the test. A new nine-class disease scale was established and a Rhizoctonia index (RI) was calculated. Reliability of disease assessment was demonstrated on progeny of plants, selected from segregating populations, showing Rhizoctonia resistance more closely related to the resistant parent lines than to the susceptible ones. Sugar beet varieties could be assessed in the greenhouse within only 11 weeks. All varieties were affected by the pathogen but partially resistant varieties could be clearly recognized by a significantly lower Rhizoctonia index. Significant differences in susceptibility were also found within the group of new resistant genotypes. Infection studies performed in the field showed the superiority of the new liquid inoculum compared with a solid form and revealed the influence of inoculation date and inoculum level on the development of Rhizoctonia root rot. In field tests performed at different sites under different environmental conditions, susceptible and partially resistant sugar beet varieties could be reproducibly rated according to their susceptibility to R. solani. On average, susceptible varieties showed a Rhizoctonia index of 8 while resistant genotypes ranged from 5 to 6. The newly developed techniques allow fast and reliable evaluation of sugar beet for resistance to R. solani
The volcanic ash problem
No full textExplosive volcanic eruptions are the result of intensive magma and rock fragmentation, and they produce volcanic ash, which consists of fragments < 2 min in average diameter. The problem with volcanic ash is that its formation is poorly understood from the standpoint of eruption energetics. Because the source of explosive eruption energy should be the thermal energy of magma, and because an explosion requires rapid conversion of energy into a mechanical form, and because of the physical properties of magma thermal energy is dominantly released by conduction, the energy release on a short time scale (explosion) in volcanic processes has to be the result of a special mechanism, probably a positive feedback mechanism of fragmentation and heat exchange. In fact, the most explosive volcanic explosions are characterized by the most intensive fragmentation. In any fragmentation mechanism the generated particle sizes reflect the kinetic energy available (i.e. the fragmentation energy density). Consequently, fine ash (less than or equal to 64 mum) provides information on fragmentation mechanisms that are the most energetic and related to the highest explosive energy release. In this letter we discuss mechanisms of formation of fine volcanic ash, using experimental results, theoretical considerations, and field observations. We focus on the potency of these mechanisms to explain fine ash produced by explosive volcanism. We conclude that quantitative analysis of fine ash particles is necessary to estimate the mechanical energy of volcanic explosions
Identifying magma-water interaction from the surface features of ash particles
No full textThe deposits from explosive volcanic eruptions (those eruptions that release mechanical energy over a short time span(1)) are characterized by an abundance of volcanic ash(2,3). This ash is produced by fragmentation of the magma driving the eruption and by fragmenting and ejecting parts of the pre-existing crust (host rocks). Interactions between rising magma and the hydrosphere (oceans, lakes, and ground water) play an important role in explosive volcanism(4,5), because of the unique thermodynamic properties of water that allow it to very effectively convert thermal into mechanical energy, Although the relative proportion of magma to host-rock fragments is well preserved in the pyroclastic rocks deposited by such eruptions, it has remained difficult to quantitatively assess the interaction of magma with liquid water from the analysis of pyroclastic deposits(2-5). Here we report the results of a study of natural pyroclastic sequences combined with scaled laboratory experiments. We find that surface features of ash grains can be used to identify the dynamic contact of magma with liquid water, The abundance of such ash grains can then be related to the water/magma mass ratios during their interaction
Development of risk mitigation guidance for sensor placement inside mechanically ventilated enclosures – Phase 1
No full textGuidance on Sensor Placement was identified as the top research priority for hydrogen sensors at the 2018 HySafe Research Priority Workshop on hydrogen safety in the category Mitigation, Sensors, Hazard Prevention, and Risk Reduction. This paper discusses the initial steps (Phase 1) to develop such guidance for mechanically ventilated enclosures. This work was initiated as an international collaborative effort to respond to emerging market needs related to the design and deployment equipment for hydrogen infrastructure that is often installed in individual equipment cabinets or ventilated enclosures. The ultimate objective of this effort is to develop guidance for an optimal sensor placement such that, when in-tegrated into a facility design and operation, will allow earlier detection at lower levels of incipient leaks, leading to significant hazard reduction. Reliable and consistent early warning of hydrogen leaks will allow for the risk mitigation by reducing or even elimi-nating the probability of escalation of small leaks into large and uncontrolled events. To address this issue, a study of a real-world mechanically ventilated enclosure containing GH2 equipment was conducted, where CFD modeling of the hydrogen dispersion (performed by AVT and UQTR, and independently by the JRC) was validated by the NREL Sensor laboratory using a Hydrogen Wide Area Monitor (HyWAM) consisting of a 10-point gas and temperature measurement analyzer. In the release test, helium was used as a hydrogen surrogate. Expansion of indoor releases to other larger facilities (including parking struc-tures, vehicle maintenance facilities and potentially tunnels) and incorporation into QRA tools, such as HyRAM is planned for Phase 2. It is anticipated that results of this work will be used to inform national and international standards such as NFPA 2 Hydrogen Technologies Code, Canadian Hydrogen Installation Code (CHIC) and relevant ISO/TC 197 and CEN documents. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
Great Sumatra Earthquake Registers on Electrostatic Sensor
No full textStrong electrical signals that correspond to
the Mw = 9.3 earthquake of 26 December 2004,
which occurred at 0058:50.7 UTC
off the west coast of northern Sumatra, Indonesia,
were recorded by an electrostatic sensor
(a device that detects short-term variations in
Earth’s electrostatic fi eld) at a seismic station
in Italy, which had been installed to study the
infl uence of local earthquakes on a new landslide
monitoring system
MSI-testing in hereditary non-polyposis colorectal carcinoma (HNPCC)
No full textGenomic instability at simple repeated sequences, termed microsatellite instability (MSI). plays an important role in the analysis of sporadic and hereditary colon cancers. In hereditary non-polyposis colorectal cancer syndrome (HNPCC) more than 90% of cases show MSI, whereas only 10-15% of sporadic colorectal cancers do so. Thus. microsatellite analysis is commonly used as the first diagnostic screening test for HNPCC. In 1997, an international collaborative workshop sponsored by the National Cancer Institute (NCI) proposed a set of guidelines for MSI-testing to improve reliability and reproducibility of the analysis as well to allow comparisons between different studies and different laboratories. In this review we assess the value of current protocols for MSI-testing and discuss some diagnostic pitfalls. Our findings support continued use of the MSI marker panel recommended in 1997. Additionally, MSI-testing should be. improved by use of microdissection, which helps to identify additional patients with MSI due to enrichment of tumor cells and therefore increased sensitivity. In our view. immunohistochemical staining for mismatch repair protein expression is not a substitute for MSI-analysis but complements MSI screening and helps direct further testing. In summary, MSI-analysis is a highly sensitive and reliable screening method for HNPCC, that requires a well-equipped laboratory, as well as an experienced pathologist. Integration of family history and histo-pathological features is also critical.NCI NIH HHS [R01 CA067007
MSI-testing in hereditary non-polyposis colorectal carcinoma (HNPCC)
No full textGenomic instability at simple repeated sequences, termed microsatellite instability (MSI). plays an important role in the analysis of sporadic and hereditary colon cancers. In hereditary non-polyposis colorectal cancer syndrome (HNPCC) more than 90% of cases show MSI, whereas only 10-15% of sporadic colorectal cancers do so. Thus. microsatellite analysis is commonly used as the first diagnostic screening test for HNPCC. In 1997, an international collaborative workshop sponsored by the National Cancer Institute (NCI) proposed a set of guidelines for MSI-testing to improve reliability and reproducibility of the analysis as well to allow comparisons between different studies and different laboratories. In this review we assess the value of current protocols for MSI-testing and discuss some diagnostic pitfalls. Our findings support continued use of the MSI marker panel recommended in 1997. Additionally, MSI-testing should be. improved by use of microdissection, which helps to identify additional patients with MSI due to enrichment of tumor cells and therefore increased sensitivity. In our view. immunohistochemical staining for mismatch repair protein expression is not a substitute for MSI-analysis but complements MSI screening and helps direct further testing. In summary, MSI-analysis is a highly sensitive and reliable screening method for HNPCC, that requires a well-equipped laboratory, as well as an experienced pathologist. Integration of family history and histo-pathological features is also critical.NCI NIH HHS [R01 CA067007
Thermohydraulic explosions in phreatomagmatic eruptions as evidenced by the comparison between pyroclasts and products from Molten Fuel Coolant Interaction experiments
No full textThermohydraulic explosions were produced by Molten Fuel Coolant Interaction (MFCI) experiments using remelted shoshonitic rocks from Vulcano (Italy). The fragmentation history and energy release were recorded. The resulting products were recovered and analyzed with the scanning electron microscope. Fine particles from experiments show shape and surface features that result from melt fragmentation in brittle mode. These clasts relate to the thermohydraulic phase of the MFCI, where most of the mechanical energy is released; they are here called "active'' particles. The total surface area of such particles is proportional to the energy of the respective explosions. Other particles from experiments show shape and surface features that result from melt fragmentation in a ductile regime. These fragments, called "passive'' particles, form after the thermohydraulic phase, during the expansion phase of the MFCI. In order to verify thermohydraulic explosions in volcanic eruptions, we compared experimental products with samples from phreatomagmatic base-surge deposits of Vulcano. Ash particles from the experiments show features similar to those from the deposits, suggesting that the experiments reproduced the same fragmentation dynamics. To achieve discrimination between active and passive particles, we calculated shape parameters from image analysis. The mass of active particles in base-surge deposits was calculated. As the material properties for the natural samples are identical to the experimental ones, the energy measurements and calculations of the experiments can be applied. For a single phreatomagmatic eruption at Vulcano, a maximum mechanical energy release of 2.75 x 10(13) J was calculated, representing a TNT analogue of 6.5 kt
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