Recurrent selection for European corn borer resistance in a maize synthetic

The release of the corn (Zea mays L.) synthetic, BS9(CB)C4, to the hybrid seed industry in 1982 was a significant event to host-plant resistance investigations because it was the first released Corn Belt synthetic specifically developed and selected for resistance to European corn borer (ECB), Ostrinia nubilalis (Hubner), for the whole life of the plant. To determine the efficacy of S(,1) recurrent selection for resistance to the two generations of ECB normally found in Iowa, the base population and four succeeding cycles of selection of BS9 were evaluated for ECB resistance and correlated effects on agronomic traits;Significant increases were found from BS9C0 to BS9(CB)C4 for resistance to first generation (leaf-feeding), second generation (sheath-collar feeding), and stalk tunneling (cavity counts). Averaged over means of S(,1) lines, populations per se, and population testcrosses, ECB damage ratings based on a 1 to 9 scale decreased from 3.9 to 3.0 for first generation and from 6.0 to 4.3 for second generation in BS9C0 and BS9(CB)C4, respectively. Similarly, the average of populations per se and population testcrosses for cavity counts (one cavity is ca. 2.5 cm) decreased from 8.2 to 4.0 in the two populations, respectively;The increase in resistance in populations of BS9 reduced yield losses under artificial infestations of ECB, but the reduction was not sufficient to compensate for the loss in yielding ability that occurred as a correlated effect from selection for ECB resistance. Reduction in the grain yield from BS9C0 to BS9(CB)C4 under no artificial infestation was estimated to be 8.4% caused by changes in gene frequency due to selection and 18.8% caused by inbreeding depression due to drift. Most of the yield reduction, therefore, was caused by a random fixation of heterozygous loci, which may have been increased because of linkages to alleles of other traits under direct and indirect selection. Ear diameter, ear height, and plant height decreased in BS9 possibly as a result of indirect selection for shorter internode length to improve stalk hardness and, thereby, stalk-tunneling resistance;S(,1) recurrent selection, therefore, was effective in increasing resistance throughout the life of the corn plant, but unfavorable responses in other agronomic traits, particularly in grain yield, suggest that the selection criteria for ECB resistance should include yield

High-average-power femtosecond laser at 258 nm

We present an ultrafast fiber laser system delivering 4.6 W average power at 258 nm based on two-stage fourth-harmonic generation in beta barium borate (BBO). The beam quality is close to being diffraction limited with an M2 value of 1.3×1.6. The pulse duration is 150 fs, which, potentially, is compressible down to 40 fs. A plain BBO and a sapphire-BBO compound are compared with respect to the achievable beam quality in the conversion process. This laser is applicable in scientific and industrial fields. Further scaling to higher average power is discussed

Method and device for maximizing memory system bandwidth by accessing data in a dynamically determined order

A data processing system is disclosed which comprises a data processor and memory control device for controlling the access of information from the memory. The memory control device includes temporary storage and decision ability for determining what order to execute the memory accesses. The compiler detects the requirements of the data processor and selects the data to stream to the memory control device which determines a memory access order. The order in which to access said information is selected based on the location of information stored in the memory. The information is repeatedly accessed from memory and stored in the temporary storage until all streamed information is accessed. The information is stored until required by the data processor. The selection of the order in which to access information maximizes bandwidth and decreases the retrieval time

High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafast molecular dynamics with table-top XUV-photon sources. These table-top sources can provide significantly higher repetition rates than the currently operating free-electron lasers and they offer very high temporal resolution due to the intrinsically small timing jitter between pump and probe pulses

Energetic sub-2-cycle laser with 216 W average power

Few-cycle lasers are essential for many research areas such as attosecond physics that promise to address fundamental questions in science and technology. Therefore, further advancements are connected to significant progress in the underlying laser technology. Here, two-stage nonlinear compression of a 660 W femtosecond fiber laser system is utilized to achieve unprecedented average power levels of energetic ultrashort or even few-cycle laser pulses. In a first compression step, 408 W, 320 mu J, 30 fs pulses are achieved, which can be further compressed to 216 W, 170 mu J, 6.3 fs pulses in a second compression stage. To the best of our knowledge, this is the highest average power few-cycle laser system presented so far. It is expected to significantly advance the fields of high harmonic generation and attosecond science. (C) 2016 Optical Society of Americ

Toward a more rigorous application of margins and uncertainties within the nuclear weapons life cycle : a Sandia perspective.

This paper presents the conceptual framework that is being used to define quantification of margins and uncertainties (QMU) for application in the nuclear weapons (NW) work conducted at Sandia National Laboratories. The conceptual framework addresses the margins and uncertainties throughout the NW life cycle and includes the definition of terms related to QMU and to figures of merit. Potential applications of QMU consist of analyses based on physical data and on modeling and simulation. Appendix A provides general guidelines for addressing cases in which significant and relevant physical data are available for QMU analysis. Appendix B gives the specific guidance that was used to conduct QMU analyses in cycle 12 of the annual assessment process. Appendix C offers general guidelines for addressing cases in which appropriate models are available for use in QMU analysis. Appendix D contains an example that highlights the consequences of different treatments of uncertainty in model-based QMU analyses

A planet within the debris disk around the pre-main-sequence star AU Microscopii

AU Microscopii (AU Mic) is the second closest pre main sequence star, at a distance of 9.79 parsecs and with an age of 22 million years. AU Mic possesses a relatively rare and spatially resolved3 edge-on debris disk extending from about 35 to 210 astronomical units from the star, and with clumps exhibiting non-Keplerian motion. Detection of newly formed planets around such a star is challenged by the presence of spots, plage, flares and other manifestations of magnetic activity on the star. Here we report observations of a planet transiting AU Mic. The transiting planet, AU Mic b, has an orbital period of 8.46 days, an orbital distance of 0.07 astronomical units, a radius of 0.4 Jupiter radii, and a mass of less than 0.18 Jupiter masses at 3 sigma confidence. Our observations of a planet co-existing with a debris disk offer the opportunity to test the predictions of current models of planet formation and evolution.Comment: Nature, published June 24th [author spelling name fix