Progress in crystal extraction and collimation

Recent IHEP Protvino experiments show efficiencies of crystal-assisted slow extraction and collimation of 85.3+-2.8%, at the intensities of the channeled beam on the order of 10^12 proton per spill of 2 s duration. The obtained experimental data well follows the theory predictions. We compare the measurements against theory and outline the theoretical potential for further improvement in the efficiency of the technique. This success is important for the efficient use of IHEP accelerator and for implementation of crystal-assisted collimation at RHIC and slow extraction from AGS onto E952, now in preparation. Future applications, spanning in the energy from order of 1 GeV (scraping in SNS, slow extraction from COSY and medical accelerators) to order of 1 TeV and beyond (scraping in Tevatron, LHC, VLHC), can benefit from these studies.Comment: 7pp. Presented at HEACC 2001 (Tsukuba, March 25-30

Screening pearl millet against Eritrean isolates of downy mildew

Following the downy mildew survey in 2000, a unique scientific collaboration between Eritrea, ICRISAT and the Centre for Ariz Zone Studies (CAZS) at Bangor, Wales, UK, has produced valuable data on the resistance of 70 pearl millet genotypes to an Eritrean isolate of the pathogen (Sclerospora graminicola). Screening of the genotypes, which included Eritrean landraces and promising new cultivars from ICRISAT populations, was done in a tropical greenhouse at the CAZS. Susceptible control genotypes 7042(S) and HB 3 showed approximately 50% infection (rather less than expected), and the resistant control genotype P 7-3 proved surprisingly susceptible to this isolate of the pathogen. The Bultug Keren landrace was particularly susceptible with an overall mean infection of 79.5%. Three introduced male-sterile lines (ICMA 98333, ICMA 92444 and ICMA 00888) had 0% infection, while three other introductions (ICMA 99111, P 1449-2 and P 310-17B) showed <2% downy mildew incidence

Crystal experiments on efficient beam extraction

Silicon crystal was channeling and extracting 70-GeV protons from the U-70 accelerator with efficiency of 85.3+-2.8% as measured for a beam of 10^12 protons directed towards crystals of 2 mm length in spills of 1-2 s duration. The experimental data follow very well the prediction of Monte Carlo simulations. This success is important to devise a more efficient use of the U-70 accelerator in Protvino and provides a crucial support for implementation of crystal-assisted collimation of gold ion beam in RHIC and slow extraction from AGS onto E952, now in preparation at Brookhaven Nat'l Lab. Future applications, spanning in the energy from sub-GeV (medical) to order of 1 GeV (scraping in the SNS, extraction from COSY) to order of 1 TeV and beyond (scraping in the Tevatron, LHC, VLHC), can benefit from these studies.Comment: 12pp. Presented at 19-th Intern. Conference on Atomic Collisions in Solids (ICACS-19: Paris, July 29 - August 3, 2001

The Investigations Of Beam Extraction And Collimation At U-70 Proton Synchrotron Of IHEP By Using Short Silicon Crystals

The new results of using short (2-4mm) bent crystals for extraction and collimation of proton beam at IHEP 70 Gev proton synchrotron are reported. A broad range of energies from 6 to 65 GeV has been studied in the same crystal collimation set-up. The efficiency of extraction more than 85% and intensity more than 10E12 were obtained by using crystal with the length 2-mm and the angle 1 mrad. The new regime of extraction is applied now at the accelerator to deliver the beam for different experimental setups within the range of intensity 10E7-10E12ppp.Comment: Presented at EPAC 2002 (Paris, June 3-7), 3p

The improvement of crop yield in marginal environments using ‘on-farm’ seed priming: nodulation, nitrogen fixation, and disease resistance

On-farm seed priming with water is a low-cost, low-risk technology that is easily adopted by resource-poor farmers. It increases the yield of tropical and subtropical annual crops in marginal areas by a combination of better crop establishment and improved individual plant performance. The effects of seed priming, i.e. soaking seeds overnight in water before sowing, on plant growth and development are consequences of faster germination, emergence, and more vigorous early growth. Results from in-vitro, on-station and on-farmexperiments are discussed. Recent work has tested opportunities for resource-poor farmers to use seed priming as a vehicle for applying biofertilisers (Rhizobia). Preliminary results from field experiments suggest that these interventions are very effective over and above the already demonstrated benefits of priming with water alone. In a pot experiment using chickpea, combining a Rhizobium inoculation with seed priming significantly increased nodulation but had little effect on yield. Nevertheless, the results confirmed that Rhizobium inoculation is compatible with on-farm seed priming. Observations in the field have shown that some primed crops show enhanced resistance to disease, either as a consequence of increased vigour, altered phenology, or due to some more fundamental mechanism associated with exposure of seeds to anaerobic conditions during priming. Priming seeds of a highly susceptible cultivar of pearl millet in water for 8 h before sowing significantly reduced the incidence of downy mildew in artificially infected seedlings from 80% to less than 60%

Channeling of Positrons through Periodically Bent Crystals: on Feasibility of Crystalline Undulator and Gamma-Laser

The electromagnetic radiation generated by ultra-relativistic positrons channelling in a crystalline undulator is discussed. The crystalline undulator is a crystal whose planes are bent periodically with the amplitude much larger than the interplanar spacing. Various conditions and criteria to be fulfilled for the crystalline undulator operation are established. Different methods of the crystal bending are described. We present the results of numeric calculations of spectral distributions of the spontaneous radiation emitted in the crystalline undulator and discuss the possibility to create the stimulated emission in such a system in analogy with the free electron laser. A careful literature survey covering the formulation of all essential ideas in this field is given. Our investigation shows that the proposed mechanism provides an efficient source for high energy photons, which is worth to study experimentally.Comment: 52 pages, MikTeX, 14 figure

Mapping quantitative trait Loci for resistance to downy mildew in pearl millet: field and glasshouse screens detect the same QTL

Downy mildew, caused by the pathogen Sclerospora graminicola (Sacc.) J. Schrot, can cause devastating yield losses in pearl millet [Pennisetum glaucum (L.) R. Br.]. Breeding for resistance to downy mildew is facilitated by an artificial glasshouse screening method that can be used worldwide. Quantitative trait loci (QTLs) mapping was used to determine whether resistance QTLs identified under field conditions in India were also detected in glasshouse screens carried out in India and the UK. Quantitative trait loci were mapped using 114 individual pearl millet progeny derived from a resistant x susceptible cross: molecular marker mapping was carried out in an F2 population with restriction fragment length polymorphisms (RFLPs), and disease incidence was assessed on F4 families. Composite interval mapping (CIM) was used to detect associations between F4 family means and marker genotypes. Despite key environmental and methodological differences between the disease screens, the same two QTLs were detected in each screening environment. One QTL had a major effect and explained up to 60% of the phenotypic variation, while the other had a minor effect and explained up to 16% of the phenotypic variation. Two additional QTLs were also consistently detected across screens by examining pair-wise marker interactions. Multiple-trait interval mapping detected all of the QTLs that had been detected in individual screens, including the QTLs that had only been detected by examining pair-wise marker interactions, demonstrating its increased power over single trait mapping. Quantitative trait locus x environment interactions were significant at each QTL due to differences in the magnitude, rather than direction, of QTL effects. The differences in magnitude appeared to be a consequence of the degree of normality of the disease distribution, rather than any differences between screening methods

Predicting temporary threshold shifts in a bottlenose dolphin (Tursiops truncatus) : the effects of noise level and duration

Author Posting. © Acoustical Society of America, 2009. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 125 (2009): 1816-1826, doi:10.1121/1.3068456.Noise levels in the ocean are increasing and are expected to affect marine mammals. To examine the auditory effects of noise on odontocetes, a bottlenose dolphin (Tursiops truncatus) was exposed to octave-band noise (4–8 kHz) of varying durations (<2–30 min) and sound pressures (130–178 dB re 1 µPa). Temporary threshold shift (TTS) occurrence was quantified in an effort to (i) determine the sound exposure levels (SELs) (dB re 1 µPa2 s) that induce TTS and (ii) develop a model to predict TTS onset. Hearing thresholds were measured using auditory evoked potentials. If SEL was kept constant, significant shifts were induced by longer duration exposures but not for shorter exposures. Higher SELs were required to induce shifts in shorter duration exposures. The results did not support an equal-energy model to predict TTS onset. Rather, a logarithmic algorithm, which increased in sound energy as exposure duration decreased, was a better predictor of TTS. Recovery to baseline hearing thresholds was also logarithmic (approximately −1.8 dB/doubling of time) but indicated variability including faster recovery rates after greater shifts and longer recoveries necessary after longer duration exposures. The data reflected the complexity of TTS in mammals that should be taken into account when predicting odontocete TTS.This work was funded by the Office of Naval Research Grant No. 00014-098-1-687 to P.E.N. and the support of Bob Gisiner and Mardi Hasting is noted. Additional support came from SeaSpace to T.A.M