Improved Fast Neutron Spectroscopy via Detector Segmentation

Organic scintillators are widely used for fast neutron detection and spectroscopy. Several effects complicate the interpretation of results from detectors based upon these materials. First, fast neutrons will often leave a detector before depositing all of their energy within it. Second, fast neutrons will typically scatter several times within a detector, and there is a non-proportional relationship between the energy of, and the scintillation light produced by, each individual scatter; therefore, there is not a deterministic relationship between the scintillation light observed and the neutron energy deposited. Here we demonstrate a hardware technique for reducing both of these effects. Use of a segmented detector allows for the event-by-event correction of the light yield non-proportionality and for the preferential selection of events with near-complete energy deposition, since these will typically have high segment multiplicities.Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Research Section

Artemisia annua l. As an alternative potential weed control option

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Ultrastructural and molecular characterization of altered plastids in nuclear gene controlled yellow stripe mutant of Pennisetum americanum

The ultrastructural and molecular biological studies were conducted to elucidate the changes in the nuclear gene controlled plastid alterations in yellow stripe mutant of Pennisetum americanum. The plastids in yellow tissue were bound by a double membrane envelope and no internal thylakoid membrane differentiation, whereas plastid development was normal in the green tissue. The nuclear gene apparently influences the individual plastids as evidenced by the presence of heteroplastidic cells. Ribosomal RNAs were extracted from green and yellow seedlings with homozygous recessive and heterozygous genotypes. Plastid specific 23S and 16S rRNAs were absent in the yellow seedlings irrespective of the genotype. The presence of disorganized lamellar membranes in the rRNA/ribosome deficient plastids indicate that they are synthesized outside the plastid compartment. Restriction endonuclease analysis revealed no detectable differences in fragmentation pattern of the plastid DNAs from green and reverted green seedlings. This is consistent with the suggestion that the nuclear gene is not inducing any change in the plastid genome size and in the restriction enzyme recognition sites

Inheritance of stripe in pearl millet

A nonlethal chlorophyll-deficient mutant named stripe was detected in a pearl millet (Pennisetum americanum (L.) Leeke) accession IP-5009 collected from Nigeria. The stripe plants showed longltudinal yellow stripes alternating with green stripes on leaf blades, leaf sheaths, stems. peduncles, inflorescences, and spikelets. The stripe plants segregated yellow, stripe, and green depending on the number and size of the yellow stripes on the leaf blade. Segregation data from crosses of green and stripe plants did not fit a definite Mendelian ratio. The spikes of the stripe plants have yellow and green spikelets and when yellow spikelets were crossed with green spikelets, segregation data indicated that the yellow spikelet color was monogenic recessive to the green color. Since the yellow and green sectors that are genetically different from each other lie adjacent to each other, the stripe plants are considered to be chimeras

Germplasm From SADCC Countries Maintained At ICRISAT Center And Its Implications On National Programs

The area covered by Southern African Development Coordination Conference (SADCC) member countries extend from near the equator to about 30' S latitude and 11'-41' E longitude. The area has a wide range of environmental conditions ;and ecosystems~ dry areas in the Kalahari desert in Botswana; tropical rainfall in Anqola; coastal climate in Mozambique to continental Zambia; high plateaux in Angola and river basins in Zimbabwe; high altitudes in Lesotho and low' elevations in Tanzania. The dominant cereal crop in the region is maize (Zed mays L. ) followed by sorghum [Sorghum bicolor (L. ) Moenche], pearl millet [Pennisetum glaucum (L, ) R.Br. 1, and finger millet [Eleusine coracana (L. ) Gaertn. ] Among the legumes, groundnut (Arachis hypogaea L. ) is an important crop followed by chickpea (Cicer arietinurn L. ), and then pigeonpea [Cajanus cajan (L.) Millsp. 1, which is usually grown i n backyards

Status and Diversity of African Germplasm Collections Maintained at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)

One of the major objectives of the International Crops Research Institute for the Serni-Arid Tropics (ICRISAT) is to act as a world repository for the genetic resources of its mandate crops: sorghi~mS,o t-gltirntb icolot.(L.)M ocnch: pearl millet, Petllliscrtrnt glatrc~rn(L~ .) R. Br.; chickpea, Ciccr nr-ietittirnl L.; pigeonpea, Cc~jjcrttirsc ajntl (L.)M ill.: and groundnut, Arachis Ilypognen L.. The Institute also assembles and conserves the gennplasm of six minor millets: finger millet; Ele~tsitlec ot.acatln (L.) Gaertn.; foxtail millet, Serai.ia irnlica (L.)P . Beauv.; proso millet, Pntlic~rnt sttntart.ettse Roth. ex Roem. & Schult.; barnyard nill let, Echinoclrloa species; and kodo millet, Pnspcilrrnl sc~+obicrrlntrrnL1. The usefulness of any world germplasm collection, such as the one assernbled at ICRISAT, depends largely on proper sampling from various agroclirnatic zones, the long-term safety and viability of the conserved material, the genetic diversity i t offers in both cultivated landraces and their wild relatives, the accessibility of healthy seed samples along with their passport and evaluation data, appropriate maintenance of the gerniplasm accessions to minimize genetic drift, and the availability of a simple, classified and retrievable documentation systen

Collection Strategies for Food Legumes

Food legumes are consumed as dry seeds, green seeds or the green pods with irmture seeds inside. They are rich i n protein and thus form a natural supplement to carbhydrate-rich foods. This paper addresses the principles of germplasm collection, with reference mainly to one important cool season food legume, chickpea (-Cicer a rietinum L.). Th i s species is known to have originated in Turkey, 'and the crop i s now cultivated under a much wider range of climatic conditions than occurs in that country, i.e., from temperate to subtropical. Chickpea is a self-pollinated crop. Germplasm accessions of chickpea are collected from dry seeds. Collection strategies and some guidelines are discussed in this paper. Other crops are referred to as examples of special cases or uses