An Evaluation of Proposed Mechanisms of Slab Flattening in Central Mexico

Central Mexico is the site of an enigmatic zone of flat subduction. The general geometry of the subducting slab has been known for some time and is characterized by a horizontal zone bounded on either side by two moderately dipping sections. We systematically evaluate proposed hypotheses for shallow subduction in Mexico based on the spatial and temporal evidence, and we find no simple or obvious explanation for the shallow subduction in Mexico. We are unable to locate an oceanic lithosphere impactor, or the conjugate of an impactor, that is most often called upon to explain shallow subduction zones as in South America, Japan, and Laramide deformation in the US. The only bathymetric feature that is of the right age and in the correct position on the conjugate plate is a set of unnamed seamounts that are too small to have a significant effect on the buoyancy of the slab. The only candidate that we cannot dismiss is a change in the dynamics of subduction through a change in wedge viscosity, possibly caused by water brought in by the slab

The lack of correlation between flat slabs and bathymetric impactors in South America

Flat slab subduction has been attributed to various causes including mantle wedge dynamics, overriding by the upper plate, age of the subducting plate, and subduction of anomalously thick oceanic crust. One often favored explanation for flat slabs is the subduction of buoyant features on the oceanic plate in the form of an aseismic-ridge or oceanic plateau. We show through plate tectonic reconstructions of the Marquesas, Tuamotu, and Austral plateau, assuming that features on the conjugate plate can be used as proxies for subducted bathymetric anomalies, that there is very little correlation between the subduction of such anomalies and historic zones of flat subduction in South America. It is apparent that subduction of a bathymetric anomaly need not lead to a flat slab and not all flat slabs are associated with the subduction of a bathymetric anomaly

Cavallo's Multiplier for in situ Generation of High Voltage

A classic electrostatic induction machine, Cavallo's multiplier, is suggested for in situ production of very high voltage in cryogenic environments. The device is suitable for generating a large electrostatic field under conditions of very small load current. Operation of the Cavallo multiplier is analyzed, with quantitative description in terms of mutual capacitances between electrodes in the system. A demonstration apparatus was constructed, and measured voltages are compared to predictions based on measured capacitances in the system. The simplicity of the Cavallo multiplier makes it amenable to electrostatic analysis using finite element software, and electrode shapes can be optimized to take advantage of a high dielectric strength medium such as liquid helium. A design study is presented for a Cavallo multiplier in a large-scale, cryogenic experiment to measure the neutron electric dipole moment.Comment: 9 pages, 10 figure

Using yield response curves to measure variation in the tolerance and resistance of wheat cultivars to Fusarium crown rot

The disease crown rot, caused predominantly by the fungal pathogen Fusarium pseudograminearum (Fp), is a major disease of winter cereals in many regions of the world, including Australia. A methodology is proposed, using response curves, to robustly estimate the relationship between grain yield and increasing crown rot pathogen burdens. Using data from a field experiment conducted in northern New South Wales, Australia in 2016, response curves were derived for five commercial wheat cultivars exposed to six increasing rates of crown rot inoculum, where the rates served to establish a range of crown rot pathogen burdens. In this way, the response curve methodology is fundamentally different from alternate approaches that rely on genetic or environmental variation to establish a range in pathogen burdens over which yield loss relationships are estimated. By manipulating only the rates of crown rot inoculum and thus pathogen burden directly, the number of additional confounding factors and interactions are minimised, enabling the robust estimation of the rate of change in yield due to increasing crown rot pathogen burdens for each cultivar. The methodology revealed variation in the rate of change in yield between cultivars, along with the extent of crown rot symptoms expressed by the cultivars. Variation in the rate of change in yield between cultivars provides definitive evidence of differences in the tolerance of commercial Australian wheat cultivars to crown rot caused by Fp, while variation in the extent of crown rot symptoms signifies differences in the resistance of the cultivars to this disease. The response curve methodology also revealed variation in how the different mechanisms of tolerance and resistance act to limit yield losses due to crown rot for different cultivars

Integration of microarray analysis into the clinical diagnosis of hematological malignancies: How much can we improve cytogenetic testing?

PurposeTo evaluate the clinical utility, diagnostic yield and rationale of integrating microarray analysis in the clinical diagnosis of hematological malignancies in comparison with classical chromosome karyotyping/fluorescence in situ hybridization (FISH).MethodsG-banded chromosome analysis, FISH and microarray studies using customized CGH and CGH+SNP designs were performed on 27 samples from patients with hematological malignancies. A comprehensive comparison of the results obtained by three methods was conducted to evaluate benefits and limitations of these techniques for clinical diagnosis.ResultsOverall, 89.7% of chromosomal abnormalities identified by karyotyping/FISH studies were also detectable by microarray. Among 183 acquired copy number alterations (CNAs) identified by microarray, 94 were additional findings revealed in 14 cases (52%), and at least 30% of CNAs were in genomic regions of diagnostic/prognostic significance. Approximately 30% of novel alterations detected by microarray were >20 Mb in size. Balanced abnormalities were not detected by microarray; however, of the 19 apparently "balanced" rearrangements, 55% (6/11) of recurrent and 13% (1/8) of non-recurrent translocations had alterations at the breakpoints discovered by microarray.ConclusionMicroarray technology enables accurate, cost-effective and time-efficient whole-genome analysis at a resolution significantly higher than that of conventional karyotyping and FISH. Array-CGH showed advantage in identification of cryptic imbalances and detection of clonal aberrations in population of non-dividing cancer cells and samples with poor chromosome morphology. The integration of microarray analysis into the cytogenetic diagnosis of hematologic malignancies has the potential to improve patient management by providing clinicians with additional disease specific and potentially clinically actionable genomic alterations

Economic Impact of Beef Cattle Best Management Practices in South Texas: Stocking Strategies during Drought

In a drought situation, forage is normally reduced due to lack of adequate moisture. Moreover, the availability of hay may become limited, and hay prices often escalate. Cow-calf producers are faced with the integral decision to maintain their herds and supplemental feed or reduce the herd to minimize feeding requirements and costs. The management decision to maintain versus destock can significantly impact producer profits and financial position. This paper illustrates the financial implications of alternative management stocking strategies in a drought situation optimizing profitability of ranching operations

Seismic evidence for a fossil slab origin for the Isabella anomaly

A teleseismic receiver function image of a slab-like feature that extends from the Pacific coast to the foothills of the Sierra Nevada beneath central California connects the expected location of the subducted remnant of the Monterey microplate to the high-velocity Isabella anomaly in the upper mantle. The observed structure indicates that this anomaly is a relic of the subduction zone that preceded capture of the Monterey microplate by the Pacific plate and is not due to the delamination of the lithosphere beneath the Sierra Nevada Mountains, as had been previously proposed. The fossil slab connection is also supported by surface wave tomographic images. The images are derived in part from a new linear broad-band array across the western part of central California