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Sample records for maize streak disease

  1. Inducible Resistance to Maize Streak Virus

    PubMed Central

    Shepherd, Dionne N.; Dugdale, Benjamin; Martin, Darren P.; Varsani, Arvind; Lakay, Francisco M.; Bezuidenhout, Marion E.; Monjane, Adérito L.; Thomson, Jennifer A.; Dale, James; Rybicki, Edward P.

    2014-01-01

    Maize streak virus (MSV), which causes maize streak disease (MSD), is the major viral pathogenic constraint on maize production in Africa. Type member of the Mastrevirus genus in the family Geminiviridae, MSV has a 2.7 kb, single-stranded circular DNA genome encoding a coat protein, movement protein, and the two replication-associated proteins Rep and RepA. While we have previously developed MSV-resistant transgenic maize lines constitutively expressing “dominant negative mutant” versions of the MSV Rep, the only transgenes we could use were those that caused no developmental defects during the regeneration of plants in tissue culture. A better transgene expression system would be an inducible one, where resistance-conferring transgenes are expressed only in MSV-infected cells. However, most known inducible transgene expression systems are hampered by background or “leaky” expression in the absence of the inducer. Here we describe an adaptation of the recently developed INPACT system to express MSV-derived resistance genes in cell culture. Split gene cassette constructs (SGCs) were developed containing three different transgenes in combination with three different promoter sequences. In each SGC, the transgene was split such that it would be translatable only in the presence of an infecting MSV’s replication associated protein. We used a quantitative real-time PCR assay to show that one of these SGCs (pSPLITrepIII-Rb-Ubi) inducibly inhibits MSV replication as efficiently as does a constitutively expressed transgene that has previously proven effective in protecting transgenic maize from MSV. In addition, in our cell-culture based assay pSPLITrepIII-Rb-Ubi inhibited replication of diverse MSV strains, and even, albeit to a lesser extent, of a different mastrevirus species. The application of this new technology to MSV resistance in maize could allow a better, more acceptable product. PMID:25166274

  2. Efficient inoculation of rice black-streaked dwarf virus to maize using Laodelphax striatellus Fallen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize rough dwarf disease (MRDD) caused by Rice black-streaked dwarf virus (RBSDV) is the most important viral disease of maize in China. Although deploying disease resistant hybrids would be the most effective way to control the disease, development of resistant hybrids has been limited by virus t...

  3. Comparative analysis of Panicum streak virus and Maize streak virus diversity, recombination patterns and phylogeography

    PubMed Central

    2009-01-01

    Background Panicum streak virus (PanSV; Family Geminiviridae; Genus Mastrevirus) is a close relative of Maize streak virus (MSV), the most serious viral threat to maize production in Africa. PanSV and MSV have the same leafhopper vector species, largely overlapping natural host ranges and similar geographical distributions across Africa and its associated Indian Ocean Islands. Unlike MSV, however, PanSV has no known economic relevance. Results Here we report on 16 new PanSV full genome sequences sampled throughout Africa and use these together with others in public databases to reveal that PanSV and MSV populations in general share very similar patterns of genetic exchange and geographically structured diversity. A potentially important difference between the species, however, is that the movement of MSV strains throughout Africa is apparently less constrained than that of PanSV strains. Interestingly the MSV-A strain which causes maize streak disease is apparently the most mobile of all the PanSV and MSV strains investigated. Conclusion We therefore hypothesize that the generally increased mobility of MSV relative to other closely related species such as PanSV, may have been an important evolutionary step in the eventual emergence of MSV-A as a serious agricultural pathogen. The GenBank accession numbers for the sequences reported in this paper are GQ415386-GQ415401 PMID:19903330

  4. Mapping the distribution of maize streak virus genotypes across the forest and transition zones of Ghana.

    PubMed

    Oppong, Allen; Offei, Samuel K; Ofori, Kwadwo; Adu-Dapaah, Hans; Lamptey, Joseph N L; Kurenbach, Brigitta; Walters, Matthew; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind

    2015-02-01

    Throughout sub-Saharan Africa, maize streak virus strain A (MSV-A), the causal agent of maize streak disease (MSD), is an important biological constraint on maize production. In November/December 2010, an MSD survey was carried out in the forest and transition zones of Ghana in order to obtain MSV-A virulence sources for the development of MSD-resistant maize genotypes with agronomic properties suitable for these regions. In 79 well-distributed maize fields, the mean MSD incidence was 18.544 % and the symptom severity score was 2.956 (1 = no symptoms and 5 = extremely severe). We detected no correlation between these two variables. Phylogenetic analysis of cloned MSV-A isolates that were fully sequenced from samples collected in 51 of these fields, together with those sampled from various other parts of Africa, indicated that all of the Ghanaian isolates occurred within a broader cluster of West African isolates, all belonging to the highly virulent MSV-A1 subtype. Besides being the first report of a systematic MSV survey in Ghana, this study is the first to characterize the full-genome sequences of Ghanaian MSV isolates. The 51 genome sequences determined here will additionally be a valuable resource for the rational selection of representative MSV-A variant panels for MSD resistance screening. PMID:25344899

  5. Quantification of Maize Fine Streak Virus Genomic and Positive-sense RNAs in Infected Maize Reveals High Level Accumulation of ORF 3 and 4 MFSV Transcripts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of Maize fine streak virus genomic and positive-sense RNAs in infected maize reveals high level accumulation of ORF 3 and 4 MFSV transcripts. We improved methods to analyze RNA produced by Maize fine streak virus (MVSF) within infected maize tissue using real-time RT-qPCR. We designe...

  6. Plant host range and leafhopper transmission of Maize fine streak virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize fine streak virus (MFSV), an emerging rhabdovirus species in the genus Nucleorhabdovirus, is persistently transmitted by the black-faced leafhopper, Graminella nigrifrons (Forbes). MFSV was transmitted to maize, wheat, oats, rye, barley, foxtail, annual ryegrass and quackgrass by G. nigrifron...

  7. Nuclear import of Maize fine streak virus proteins in Drosophila S2 cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize fine streak virus (MFSV) is a member of the genus Nucleorhabdovirus, family Rhabdoviridae and is transmitted by the leafhopper Graminella nigrifons. The virus replicates in both its plant host and in its insect vector. Nucleorhabdoviruses replicate in the nucleus and assemble at the inner nu...

  8. Recombination, decreased host specificity and increased mobility may have driven the emergence of maize streak virus as an agricultural pathogen.

    PubMed

    Varsani, Arvind; Shepherd, Dionne N; Monjane, Adérito L; Owor, Betty E; Erdmann, Julia B; Rybicki, Edward P; Peterschmitt, Michel; Briddon, Rob W; Markham, Peter G; Oluwafemi, Sunday; Windram, Oliver P; Lefeuvre, Pierre; Lett, Jean-Michel; Martin, Darren P

    2008-09-01

    Maize streak virus (MSV; family Geminiviridae, genus Mastrevirus), the causal agent of maize streak disease, ranks amongst the most serious biological threats to food security in subSaharan Africa. Although five distinct MSV strains have been currently described, only one of these - MSV-A - causes severe disease in maize. Due primarily to their not being an obvious threat to agriculture, very little is known about the 'grass-adapted' MSV strains, MSV-B, -C, -D and -E. Since comparing the genetic diversities, geographical distributions and natural host ranges of MSV-A with the other MSV strains could provide valuable information on the epidemiology, evolution and emergence of MSV-A, we carried out a phylogeographical analysis of MSVs found in uncultivated indigenous African grasses. Amongst the 83 new MSV genomes presented here, we report the discovery of six new MSV strains (MSV-F to -K). The non-random recombination breakpoint distributions detectable with these and other available mastrevirus sequences partially mirror those seen in begomoviruses, implying that the forces shaping these breakpoint patterns have been largely conserved since the earliest geminivirus ancestors. We present evidence that the ancestor of all MSV-A variants was the recombinant progeny of ancestral MSV-B and MSV-G/-F variants. While it remains unknown whether recombination influenced the emergence of MSV-A in maize, our discovery that MSV-A variants may both move between and become established in different regions of Africa with greater ease, and infect more grass species than other MSV strains, goes some way towards explaining why MSV-A is such a successful maize pathogen. PMID:18753214

  9. Dual transcriptome analysis reveals insights into the response to Rice black-streaked dwarf virus in maize.

    PubMed

    Zhou, Yu; Xu, Zhennan; Duan, Canxing; Chen, Yanping; Meng, Qingchang; Wu, Jirong; Hao, Zhuanfang; Wang, Zhenhua; Li, Mingshun; Yong, Hongjun; Zhang, Degui; Zhang, Shihuang; Weng, Jianfeng; Li, Xinhai

    2016-08-01

    Maize rough dwarf disease (MRDD) is a viral infection that results in heavy yield losses in maize worldwide, particularly in the summer maize-growing regions of China. MRDD is caused by the Rice black-streaked dwarf virus (RBSDV). In the present study, analyses of microRNAs (miRNAs), the degradome, and transcriptome sequences were used to elucidate the RBSDV-responsive pathway(s) in maize. Genomic analysis indicated that the expression of three non-conserved and 28 conserved miRNAs, representing 17 known miRNA families and 14 novel miRNAs, were significantly altered in response to RBSDV when maize was inoculated at the V3 (third leaf) stage. A total of 99 target transcripts from 48 genes of 10 known miRNAs were found to be responsive to RBSDV infection. The annotations of these target genes include a SQUAMOSA promoter binding (SPB) protein, a P450 reductase, an oxidoreductase, and a ubiquitin-related gene, among others. Characterization of the entire transcriptome suggested that a total of 28 and 1085 differentially expressed genes (DEGs) were detected at 1.5 and 3.0 d, respectively, after artificial inoculation with RBSDV. The expression patterns of cell wall- and chloroplast-related genes, and disease resistance- and stress-related genes changed significantly in response to RBSDV infection. The negatively regulated genes GRMZM2G069316 and GRMZM2G031169, which are the target genes for miR169i-p5 and miR8155, were identified as a nucleolin and a NAD(P)-binding Rossmann-fold superfamily protein in maize, respectively. The gene ontology term GO:0003824, including GRMZM2G031169 and other 51 DEGs, was designated as responsive to RBSDV. PMID:27493226

  10. Dual transcriptome analysis reveals insights into the response to Rice black-streaked dwarf virus in maize

    PubMed Central

    Zhou, Yu; Xu, Zhennan; Duan, Canxing; Chen, Yanping; Meng, Qingchang; Wu, Jirong; Hao, Zhuanfang; Wang, Zhenhua; Li, Mingshun; Yong, Hongjun; Zhang, Degui; Zhang, Shihuang; Weng, Jianfeng; Li, Xinhai

    2016-01-01

    Maize rough dwarf disease (MRDD) is a viral infection that results in heavy yield losses in maize worldwide, particularly in the summer maize-growing regions of China. MRDD is caused by the Rice black-streaked dwarf virus (RBSDV). In the present study, analyses of microRNAs (miRNAs), the degradome, and transcriptome sequences were used to elucidate the RBSDV-responsive pathway(s) in maize. Genomic analysis indicated that the expression of three non-conserved and 28 conserved miRNAs, representing 17 known miRNA families and 14 novel miRNAs, were significantly altered in response to RBSDV when maize was inoculated at the V3 (third leaf) stage. A total of 99 target transcripts from 48 genes of 10 known miRNAs were found to be responsive to RBSDV infection. The annotations of these target genes include a SQUAMOSA promoter binding (SPB) protein, a P450 reductase, an oxidoreductase, and a ubiquitin-related gene, among others. Characterization of the entire transcriptome suggested that a total of 28 and 1085 differentially expressed genes (DEGs) were detected at 1.5 and 3.0 d, respectively, after artificial inoculation with RBSDV. The expression patterns of cell wall- and chloroplast-related genes, and disease resistance- and stress-related genes changed significantly in response to RBSDV infection. The negatively regulated genes GRMZM2G069316 and GRMZM2G031169, which are the target genes for miR169i-p5 and miR8155, were identified as a nucleolin and a NAD(P)-binding Rossmann-fold superfamily protein in maize, respectively. The gene ontology term GO:0003824, including GRMZM2G031169 and other 51 DEGs, was designated as responsive to RBSDV. PMID:27493226

  11. Maize Disease Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Worldwide losses in maize due to disease (not including animals or viruses) were estimated to be about 9% in 2001-3 . This varied significantly by region with estimates of 4% in northern Europe and 14% in West Africa and South Asia (http://www.cabicompendium.org/cpc/economic.asp). Losses have tende...

  12. Factors Influencing the Production of MFSV Full-Length Clone: Maize Fine Streak Virus Proteins in Drosophila S2 Cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize fine streak virus (MFSV) is negative-sense RNA virus member of the genus Nucleorhabdovirus. Our goal is to determine whether Drosophila S2 cells can support the production of a full-length clone of MFSV. We have previously demonstrated that the full-length MFSV nucleoprotein (N) and phosphopro...

  13. Transcriptome of the plant virus vector Graminella nigrifrons, and the molecular interactions of Maize fine streak rhabdovirus transmission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Leafhoppers (Hemiptera:Cicadellidae) are plant-phloem feeders that are known for their ability to vector plant pathogens. The black-faced leafhopper (Graminella nigrifrons) has been identified as the only known vector for the Maize fine streak virus (MFSV), an emerging plant pathogen in...

  14. Reconstructing the History of Maize Streak Virus Strain A Dispersal To Reveal Diversification Hot Spots and Its Origin in Southern Africa ▿ †

    PubMed Central

    Monjane, Adérito L.; Harkins, Gordon W.; Martin, Darren P.; Lemey, Philippe; Lefeuvre, Pierre; Shepherd, Dionne N.; Oluwafemi, Sunday; Simuyandi, Michelo; Zinga, Innocent; Komba, Ephrem K.; Lakoutene, Didier P.; Mandakombo, Noella; Mboukoulida, Joseph; Semballa, Silla; Tagne, Appolinaire; Tiendrébéogo, Fidèle; Erdmann, Julia B.; van Antwerpen, Tania; Owor, Betty E.; Flett, Bradley; Ramusi, Moses; Windram, Oliver P.; Syed, Rizwan; Lett, Jean-Michel; Briddon, Rob W.; Markham, Peter G.; Rybicki, Edward P.; Varsani, Arvind

    2011-01-01

    Maize streak virus strain A (MSV-A), the causal agent of maize streak disease, is today one of the most serious biotic threats to African food security. Determining where MSV-A originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. Similarly, determining where the major extant MSV-A lineages arose could identify geographical hot spots of MSV evolution. Here, we use model-based phylogeographic analyses of 353 fully sequenced MSV-A isolates to reconstruct a plausible history of MSV-A movements over the past 150 years. We show that since the probable emergence of MSV-A in southern Africa around 1863, the virus spread transcontinentally at an average rate of 32.5 km/year (95% highest probability density interval, 15.6 to 51.6 km/year). Using distinctive patterns of nucleotide variation caused by 20 unique intra-MSV-A recombination events, we tentatively classified the MSV-A isolates into 24 easily discernible lineages. Despite many of these lineages displaying distinct geographical distributions, it is apparent that almost all have emerged within the past 4 decades from either southern or east-central Africa. Collectively, our results suggest that regular analysis of MSV-A genomes within these diversification hot spots could be used to monitor the emergence of future MSV-A lineages that could affect maize cultivation in Africa. PMID:21715477

  15. Strand-specific real-time RT-PCR quantitation of Maize fine streak virus genomic and positive-sense RNAs using high temperature reverse transcription

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efforts to analyze the replicative RNA produced by Maize fine streak virus (MFSV) within maize tissue was complicated by the lack of specificity during cDNA generation using standard reverse transcriptase protocols. Real-time qRT-PCR using cDNA generated by priming with random hexamers does not dist...

  16. Strand-specific real-time RT-PCR quantitation of Maize fine streak virus genomic and positive-sense RNAs using high temperature reverse transcription

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efforts to analyze the replicative RNA produced by Maize fine streak virus (MVSF) within maize tissue was complicated by the lack of specificity during cDNA generation using standard reverse transcriptase protocols. Real-time qRT-PCR using cDNA generated by priming with random hexamers does not dist...

  17. Adaptive evolution by recombination is not associated with increased mutation rates in Maize streak virus

    PubMed Central

    2012-01-01

    Background Single-stranded (ss) DNA viruses in the family Geminiviridae are proving to be very useful in real-time evolution studies. The high mutation rate of geminiviruses and other ssDNA viruses is somewhat mysterious in that their DNA genomes are replicated in host nuclei by high fidelity host polymerases. Although strand specific mutation biases observed in virus species from the geminivirus genus Mastrevirus indicate that the high mutation rates in viruses in this genus may be due to mutational processes that operate specifically on ssDNA, it is currently unknown whether viruses from other genera display similar strand specific mutation biases. Also, geminivirus genomes frequently recombine with one another and an alternative cause of their high mutation rates could be that the recombination process is either directly mutagenic or produces a selective environment in which the survival of mutants is favoured. To investigate whether there is an association between recombination and increased basal mutation rates or increased degrees of selection favoring the survival of mutations, we compared the mutation dynamics of the MSV-MatA and MSV-VW field isolates of Maize streak virus (MSV; Mastrevirus), with both a laboratory constructed MSV recombinant, and MSV recombinants closely resembling MSV-MatA. To determine whether strand specific mutation biases are a general characteristic of geminivirus evolution we compared mutation spectra arising during these MSV experiments with those arising during similar experiments involving the geminivirus Tomato yellow leaf curl virus (Begomovirus genus). Results Although both the genomic distribution of mutations and the occurrence of various convergent mutations at specific genomic sites indicated that either mutation hotspots or selection for adaptive mutations might elevate observed mutation rates in MSV, we found no association between recombination and mutation rates. Importantly, when comparing the mutation spectra of MSV

  18. Black leaf streak disease affects starch metabolism in banana fruit.

    PubMed

    Saraiva, Lorenzo de Amorim; Castelan, Florence Polegato; Shitakubo, Renata; Hassimotto, Neuza Mariko Aymoto; Purgatto, Eduardo; Chillet, Marc; Cordenunsi, Beatriz Rosana

    2013-06-12

    Black leaf streak disease (BLSD), also known as black sigatoka, represents the main foliar disease in Brazilian banana plantations. In addition to photosynthetic leaf area losses and yield losses, this disease causes an alteration in the pre- and postharvest behavior of the fruit. The aim of this work was to investigate the starch metabolism of fruits during fruit ripening from plants infected with BLSD by evaluating carbohydrate content (i.e., starch, soluble sugars, oligosaccharides, amylose), phenolic compound content, phytohormones, enzymatic activities (i.e., starch phosphorylases, α- and β-amylase), and starch granules. The results indicated that the starch metabolism in banana fruit ripening is affected by BLSD infection. Fruit from infested plots contained unusual amounts of soluble sugars in the green stage and smaller starch granules and showed a different pattern of superficial degradation. Enzymatic activities linked to starch degradation were also altered by the disease. Moreover, the levels of indole-acetic acid and phenolic compounds indicated an advanced fruit physiological age for fruits from infested plots. PMID:23692371

  19. [Development of transgenic maize with anti-rough dwarf virus artificial miRNA vector and their disease resistance].

    PubMed

    Xuan, Ning; Zhao, Chuanzhi; Peng, Zhenying; Chen, Gao; Bian, Fei; Lian, Mingzheng; Liu, Guoxia; Wang, Xingjun; Bi, Yuping

    2015-09-01

    Maize is one of the most important food crops. Rice black-streaked dwarf virus is a maize rough dwarf disease pathogen. The occurrence and transmission of maize rough dwarf disease brings great damage to maize production. The technology of using artificial miRNA to build antiviral plant has been proven effective in a variety of plants. However, such trials in maize have not been reported. We designed primers based on the sequence of maize zea-miR159a precursor and sequence of function protein genes and silencing RBSDV coding genes in RBSDV genome. We constructed amiRNA (artificial miRNA) gene for silencing RBSDV coding gene and gene silencing suppressor. We constructed pCAMBIA3301-121-amiRNA plant expression vector for transforming maize inbred lines Z31 by using agrobacterium mediated method. After molecular analysis of transgenic maize, homozygous lines with high miRNA expression were selected by molecular detection for a subsequent natural infection experiment. We studied the severity of maize rough dwarf disease according to a grading standard (grade 0 to 4). The experiment results showed that the disease resistance of transgenic homozygous maize with the anti-rough dwarf virus amiRNA vector was better than that of wild type. Among the transgenic maize, S6-miR159 transgenic maize had high disease resistance. It is feasible to create new maize variety by the use of artificial miRNA. PMID:26955715

  20. Fine mapping of Msv1, a major QTL for resistance to Maize Streak Virus leads to development of production markers for breeding pipelines.

    PubMed

    Nair, Sudha K; Babu, Raman; Magorokosho, Cosmos; Mahuku, George; Semagn, Kassa; Beyene, Yoseph; Das, Biswanath; Makumbi, Dan; Lava Kumar, P; Olsen, Michael; Boddupalli, Prasanna M

    2015-09-01

    Msv1 , the major QTL for MSV resistance was delimited to an interval of 0.87 cM on chromosome 1 at 87 Mb and production markers with high prediction accuracy were developed. Maize streak virus (MSV) disease is a devastating disease in the Sub-Saharan Africa (SSA), which causes significant yield loss in maize. Resistance to MSV has previously been mapped to a major QTL (Msv1) on chromosome 1 that is germplasm and environment independent and to several minor loci elsewhere in the genome. In this study, Msv1 was fine-mapped through QTL isogenic recombinant strategy using a large F 2 population of CML206 × CML312 to an interval of 0.87 cM on chromosome 1. Genome-wide association study was conducted in the DTMA (Drought Tolerant Maize for Africa)-Association mapping panel with 278 tropical/sub-tropical breeding lines from CIMMYT using the high-density genotyping-by-sequencing (GBS) markers. This study identified 19 SNPs in the region between 82 and 93 Mb on chromosome 1(B73 RefGen_V2) at a P < 1.00E-04, which coincided with the fine-mapped region of Msv1. Haplotype trend regression identified a haplotype block significantly associated with response to MSV. Three SNPs in this haplotype block at 87 Mb on chromosome 1 had an accuracy of 0.94 in predicting the disease reaction in a collection of breeding lines with known responses to MSV infection. In two biparental populations, selection for resistant Msv1 haplotype demonstrated a reduction of 1.03-1.39 units on a rating scale of 1-5, compared to the susceptible haplotype. High-throughput KASP assays have been developed for these three SNPs to enable routine marker screening in the breeding pipeline for MSV resistance. PMID:26081946

  1. Behavioral responses of the leafhopper, Cicadulina storeyi China, a major vector of maize streak virus, to volatile cues from intact and leafhopper-damaged maize.

    PubMed

    Oluwafemi, Sunday; Bruce, Toby J A; Pickett, John A; Ton, Jurriaan; Birkett, Michael A

    2011-01-01

    The chemical ecology of the leafhopper, Cicadulina storeyi China (Homoptera: Cicadellidae), an important vector of Maize Streak Virus (MSV), was studied with a view to developing novel leafhopper control strategies in sub-Saharan Africa. Choice tests using a Y-tube olfactometer revealed that odors from uninfested maize seedlings (Zea mays cv. Delprim) were significantly more attractive to C. storeyi than odors from C. storeyi-infested seedlings. Headspace samples of volatile organic compounds (VOCs) collected from 10 to 12 day-old uninfested seedlings were more attractive than those collected from infested seedlings. While VOCs collected from uninfested maize seedlings were attractive, VOCs collected from C. storeyi-infested seedlings were significantly repellent. Analysis of the collected VOCs by gas chromatography (GC) and coupled GC-mass spectrometry (GC-MS) led to the identification of myrcene, linalool, (E)-2-decen-1-ol, and decanal from uninfested seedlings, and (Z)-3-hexenyl acetate, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), methyl salicylate, benzyl acetate, indole, geranyl acetate, (E)-caryophyllene, α-bergamotene, (E)-β-farnesene, β-sesquiphellandrene, and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene (TMTT) from infested seedlings. Of these, methyl salicylate, (E)-caryophyllene, (E)-β-farnesene, and TMTT were identified previously as volatile semiochemicals involved in plant defense against other sucking insect pests. When tested individually for behavioral activity, all compounds were repellent for C. storeyi. Moreover, when these induced VOCs were added to the blend of VOCs from uninfested maize seedlings, a shift from attraction to repellency was observed. Addition of methyl salicylate, (E)-β-farnesene, or TMTT resulted in a choice for the solvent control (i.e., repulsion), whereas addition of (E)-caryophyllene resulted in no reduction in host VOC attractiveness. These results show that VOCs induced in maize have the potential to be exploited

  2. Cassava brown streak disease: a threat to food security in Africa.

    PubMed

    Patil, Basavaprabhu L; Legg, James P; Kanju, Edward; Fauquet, Claude M

    2015-05-01

    Cassava brown streak disease (CBSD) has emerged as the most important viral disease of cassava (Manihot esculenta) in Africa and is a major threat to food security. CBSD is caused by two distinct species of ipomoviruses, Cassava brown streak virus and Ugandan cassava brown streak virus, belonging to the family Potyviridae. Previously, CBSD was reported only from the coastal lowlands of East Africa, but recently it has begun to spread as an epidemic throughout the Great Lakes region of East and Central Africa. This new spread represents a major threat to the cassava-growing regions of West Africa. CBSD-resistant cassava cultivars are being developed through breeding, and transgenic RNA interference-derived field resistance to CBSD has also been demonstrated. This review aims to provide a summary of the most important studies on the aetiology, epidemiology and control of CBSD and to highlight key research areas that need prioritization. PMID:26015320

  3. Computer analysis between nucleotide and amino acid sequences of bean golden mosaic virus and those of maize streak, wheat dwarf, chloris striate mosaic, and beet curly top viruses.

    PubMed

    Ikegami, M

    1989-01-01

    Bean golden mosaic virus (BGMV) DNA 1 and 2 have little sequence homology with maize streak virus (MSV), wheat dwarf virus (WDV), and chloris striate mosaic virus (CSMV) DNAs. BGMV DNA 1 and beet curly top virus (BCTV) DNA are closely related, whereas BGMV DNA 2 and BCTV DNA are not related. Direct amino acid homologies of predicted proteins between BGMV ORFs and MSV ORFs, WDV ORFs or CSMV ORFs were 40-50%. BGMV 1L1 and BCTV L1, and BGMV IL3 and BCTV L4 were highly conserved. The sequence TAATATTAC was detected in the loops of hairpin structures of 5 gemini-viruses. PMID:2615677

  4. Genetic insights into Graminella nigrifrons competence for Maize fine streak virus infection and transmission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insects are critical for the spread of most plant virus diseases, with >75% of plant viruses depending on an insects for transmission to new, uninfected hosts. However, little is known about the molecular and cellular factors in the insect that are important for virus transmission. The black-faced l...

  5. [Angioid streaks].

    PubMed

    Matonti, F; Conrath, J

    2012-12-01

    Angioid streaks represent breaks in Bruch's membrane, appearing as dark or reddish radial streaks eminating from the optic disc. Usually asymptomatic, these streaks may develop neovascularisation and lead to a maculopathy with marked loss of vision. Some associations with systemic disease are classically described, especially pseudoxanthoma elasticum. This condition may involve cardiovascular complications. A mutation has been found in the ABCC6 gene, which encodes for a membrane transport protein involved in the synthesis of the extracellular matrix. Imaging allows for visualization of the extent of the streaks, and autofluorescence is particularly informative. Spectral domain OCT may also demonstrate early breaks in Bruch's membrane. Neovascular complications, previously responsible for inevitable visual impairment at some point after their occurrence, are now managed by intravitreal injections of anti-VEGFs with clear efficacity. The ophthalmologist must be aware of this condition, in order to guide the patient towards a systemic work-up if necessary, and also to insure quick and targeted treatment in the case of neovascular complications. PMID:23046745

  6. Artificial microRNA-derived resistance to Cassava brown streak disease

    PubMed Central

    Wagaba, Henry; Patil, Basavaprabhu L.; Mukasa, Settumba; Alicai, Titus; Fauquet, Claude M.; Taylor, Nigel J.

    2016-01-01

    Artificial miRNAs (amiRNA) were generated targeting conserved sequences within the genomes of the two causal agents of Cassava brown streak disease (CBSD): Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Transient expression studies on ten amiRNAs targeting 21 nt conserved sequences of P1(CBSV and UCBSV), P3(CBSV and UCBSV), CI(UCBSV), NIb(CBSV and UCBSV), CP(UCBSV) and the un-translated region (3′-UTR) were tested in Nicotiana benthamiana. Four out of the ten amiRNAs expressed the corresponding amiRNA at high levels. Transgenic N. benthamiana plants were developed for the four amiRNAs targeting the P1 and NIb genes of CBSV and the P1 and CP genes of UCBSV and shown to accumulate miRNA products. Transgenic plants challenged with CBSV and UCBSV isolates showed resistance levels that ranged between ∼20–60% against CBSV and UCBSV and correlated with expression levels of the transgenically derived miRNAs. MicroRNAs targeting P1 and NIb of CBSV showed protection against CBSV and UCBSV, while amiRNAs targeting the P1 and CP of UCBSV showed protection against UCBSV but were less efficient against CBSV. These results indicate a potential application of amiRNAs for engineering resistance to CBSD-causing viruses in cassava. PMID:26912232

  7. Artificial microRNA-derived resistance to Cassava brown streak disease.

    PubMed

    Wagaba, Henry; Patil, Basavaprabhu L; Mukasa, Settumba; Alicai, Titus; Fauquet, Claude M; Taylor, Nigel J

    2016-05-01

    Artificial miRNAs (amiRNA) were generated targeting conserved sequences within the genomes of the two causal agents of Cassava brown streak disease (CBSD): Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Transient expression studies on ten amiRNAs targeting 21nt conserved sequences of P1(CBSV and UCBSV), P3(CBSV and UCBSV), CI(UCBSV), NIb(CBSV and UCBSV), CP(UCBSV) and the un-translated region (3'-UTR) were tested in Nicotiana benthamiana. Four out of the ten amiRNAs expressed the corresponding amiRNA at high levels. Transgenic N. benthamiana plants were developed for the four amiRNAs targeting the P1 and NIb genes of CBSV and the P1 and CP genes of UCBSV and shown to accumulate miRNA products. Transgenic plants challenged with CBSV and UCBSV isolates showed resistance levels that ranged between ∼20-60% against CBSV and UCBSV and correlated with expression levels of the transgenically derived miRNAs. MicroRNAs targeting P1 and NIb of CBSV showed protection against CBSV and UCBSV, while amiRNAs targeting the P1 and CP of UCBSV showed protection against UCBSV but were less efficient against CBSV. These results indicate a potential application of amiRNAs for engineering resistance to CBSD-causing viruses in cassava. PMID:26912232

  8. Transgenic RNA interference (RNAi)-derived field resistance to cassava brown streak disease.

    PubMed

    Ogwok, Emmanuel; Odipio, John; Halsey, Mark; Gaitán-Solís, Eliana; Bua, Anton; Taylor, Nigel J; Fauquet, Claude M; Alicai, Titus

    2012-12-01

    Cassava brown streak disease (CBSD), caused by the Ipomoviruses Cassava brown streak virus (CBSV) and Ugandan Cassava brown streak virus (UCBSV), is considered to be an imminent threat to food security in tropical Africa. Cassava plants were transgenically modified to generate small interfering RNAs (siRNAs) from truncated full-length (894-bp) and N-terminal (402-bp) portions of the UCBSV coat protein (ΔCP) sequence. Seven siRNA-producing lines from each gene construct were tested under confined field trials at Namulonge, Uganda. All nontransgenic control plants (n = 60) developed CBSD symptoms on aerial tissues by 6 months after planting, whereas plants transgenic for the full-length ΔCP sequence showed a 3-month delay in disease development, with 98% of clonal replicates within line 718-001 remaining symptom free over the 11-month trial. Reverse transcriptase-polymerase chain reaction (RT-PCR) diagnostics indicated the presence of UCBSV within the leaves of 57% of the nontransgenic controls, but in only two of 413 plants tested (0.5%) across the 14 transgenic lines. All transgenic plants showing CBSD were PCR positive for the presence of CBSV, except for line 781-001, in which 93% of plants were confirmed to be free of both pathogens. At harvest, 90% of storage roots from nontransgenic plants were severely affected by CBSD-induced necrosis. However, transgenic lines 718-005 and 718-001 showed significant suppression of disease, with 95% of roots from the latter line remaining free from necrosis and RT-PCR negative for the presence of both viral pathogens. Cross-protection against CBSV by siRNAs generated from the full-length UCBSV ΔCP confirms a previous report in tobacco. The information presented provides proof of principle for the control of CBSD by RNA interference-mediated technology, and progress towards the potential control of this damaging disease. PMID:22845735

  9. Efficient transmission of Cassava brown streak disease viral pathogens by chip bud grafting

    PubMed Central

    2013-01-01

    Background Techniques to study plant viral diseases under controlled growth conditions are required to fully understand their biology and investigate host resistance. Cassava brown streak disease (CBSD) presents a major threat to cassava production in East Africa. No infectious clones of the causal viruses, Cassava brown streak virus (CBSV) or Ugandan cassava brown streak virus (UCBSV) are available, and mechanical transmission to cassava is not effective. An improved method for transmission of the viruses, both singly and as co-infections has been developed using bud grafts. Findings Axillary buds from CBSD symptomatic plants infected with virulent isolates of CBSV and UCBSV were excised and grafted onto 6–8 week old greenhouse-grown, disease-free cassava plants of cultivars Ebwanateraka, TME204 and 60444. Plants were assessed visually for development of CBSD symptoms and by RT-PCR for presence of the viruses in leaf and storage root tissues. Across replicated experiments, 70-100% of plants inoculated with CBSV developed CBSD leaf and stem symptoms 2–6 weeks after bud grafting. Infected plants showed typical, severe necrotic lesions in storage roots at harvest 12–14 weeks after graft inoculation. Sequential grafting of buds from plants infected with UCBSV followed 10–14 days later by buds carrying CBSV, onto the same test plant, resulted in 100% of the rootstocks becoming co-infected with both pathogens. This dual transmission rate was greater than that achieved by simultaneous grafting with UCBSV and CBSV (67%), or when grafting first with CBSV followed by UCBSV (17%). Conclusions The bud grafting method described presents an improved tool for screening cassava germplasm for resistance to CBSD causal viruses, and for studying pathogenicity of this important disease. Bud grafting provides new opportunities compared to previously reported top and side grafting systems. Test plants can be inoculated as young, uniform plants of a size easily handled in a

  10. Wheat streak mosaic: A classic case of plant disease impact on soil water content and crop water-use efficiency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this article, we describe the relationship between wheat streak mosaic (WSM) severity and soil water content as a prime example of the effect of a plant disease on soil water status and its implications for irrigated agriculture. The present study was part of a larger investigation which included...

  11. Wheat Streak Mosaic: A classic case of plant disease impact on soil water content and crop water-use efficiency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this article, we describe the relationship between wheat streak mosaic (WSM) severity and soil water content as a prime example of the effect of a plant disease on soil water status and its implications for irrigated agriculture. The present study was part of a larger investigation which included...

  12. RNAi-mediated resistance to diverse isolates belonging to two virus species involved in Cassava brown streak disease.

    PubMed

    Patil, Basavaprabhu L; Ogwok, Emmanuel; Wagaba, Henry; Mohammed, Ibrahim U; Yadav, Jitender S; Bagewadi, Basavaraj; Taylor, Nigel J; Kreuze, Jan F; Maruthi, M N; Alicai, Titus; Fauquet, Claude M

    2011-01-01

    Cassava brown streak disease (CBSD) is emerging as one of the most important viral diseases of cassava (Manihot esculenta) and is considered today as the biggest threat to cassava cultivation in East Africa. The disease is caused by isolates of at least two phylogenetically distinct species of single-stranded RNA viruses belonging to the family Potyviridae, genus Ipomovirus. The two species are present predominantly in the coastal lowland [Cassava brown streak virus (CBSV); Tanzania and Mozambique] and highland [Cassava brown streak Uganda virus (CBSUV); Lake Victoria Basin, Uganda, Kenya and Malawi] in East Africa. In this study, we demonstrate that CBSD can be efficiently controlled using RNA interference (RNAi). Three RNAi constructs targeting the highland species were generated, consisting of the full-length (FL; 894 nucleotides), 397-nucleotide N-terminal and 491-nucleotide C-terminal portions of the coat protein (CP) gene of a Ugandan isolate of CBSUV (CBSUV-[UG:Nam:04]), and expressed constitutively in Nicotiana benthamiana. After challenge with CBSUV-[UG:Nam:04], plants homozygous for FL-CP showed the highest resistance, followed by the N-terminal and C-terminal lines with similar resistance. In the case of FL, approximately 85% of the transgenic plant lines produced were completely resistant. Some transgenic lines were also challenged with six distinct isolates representing both species: CBSV and CBSUV. In addition to nearly complete resistance to the homologous virus, two FL plant lines showed 100% resistance and two C-terminal lines expressed 50-100% resistance, whereas the N-terminal lines succumbed to the nonhomologous CBSV isolates. Northern blotting revealed a positive correlation between the level of transgene-specific small interfering RNAs detected in transgenic plants and the level of virus resistance. This is the first demonstration of RNAi-mediated resistance to CBSD and protection across very distant isolates (more than 25% in nucleotide

  13. Role of wheat streak mosaic virus-encoded proteins in disease development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eriophyid mite-transmitted wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are the type species of Tritimovirus and Poacevirus genera, respectively, in the family Potyviridae. TriMV and WSMV exhibit differential symptom phenotypes on wheat: TriMV elicits mild mosaic and mottling ...

  14. Chryse Streak

    NASA Technical Reports Server (NTRS)

    2006-01-01

    6 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak created in the lee -- the downwind side -- of a crater in far eastern Chryse Planitia. The winds responsible for the formation of the streak blew from the upper right (northeast) to the lower left (southwest).

    Location near: 21.5oN, 27.4oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  15. Daedalia Streak

    NASA Technical Reports Server (NTRS)

    2005-01-01

    1 December 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark wind streak formed in the lee of a crater in Daedalia Planum. The winds responsible for the streak blew from right (east) to left (west).

    Location near: 11.7oS, 136.4oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Summer

  16. Wind Streaks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 17 September 2003

    Bright wind streaks are present in the lee of craters and other obstacles in this image, located in Sinus Sabaeus, near the Martian equator. These streaks indicate that the local winds blow from the northeast (upper right in the image). The brightness of the streaks indicates that either bright material has been deposited in the lee of the craters, or that the surface has eroded preferentially in the lee of craters, exposing an underlying bright material. Because the streaks are bright regardless of the surrounding surface brightness, the first hypothesis most likely. The streaks probably all represent deposits of the same bright material that settled out of the atmosphere in the wind shelter provided by topographic peaks.

    Image information: VIS instrument. Latitude -6.3, Longitude 14.1 East (345.9 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the

  17. Seed treatments enhance photosynthesis in maize seedlings by reducing infection with Fusarium spp. and consequent disease development in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of a seed treatment on early season growth, seedling disease development, incidence Fusarium spp. infection, and photosynthetic performance of maize were evaluated at two locations in Iowa in 2007. Maize seed was either treated with Cruiser 2Extreme 250 ® (fludioxonil + azoxystrobin + me...

  18. Genetic analysis and molecular mapping of QTLs for resistance to rice black-streaked dwarf disease in rice

    PubMed Central

    Zhou, Tong; Du, Linlin; Wang, Lijiao; Wang, Ying; Gao, Cunyi; Lan, Ying; Sun, Feng; Fan, Yongjian; Wang, Guoliang; Zhou, Yijun

    2015-01-01

    Rice black-streaked dwarf disease, caused by rice black-streaked dwarf virus (RBSDV), is transmitted by small brown planthoppers (Laodelphax striatellus Fallén, SBPH) and causes severe yield loss in epidemic years in China and other East Asian countries. Breeding for resistance to RBSDV is a promising strategy to control the disease. We identified Tetep that showed resistance to RBSDV using a field test and artificial inoculation test. An evaluation of the resistance mechanism revealed that Tetep was resistant to RBSDV but not to SBPH. Genetic analysis showed that the resistance of Tetep to RBSDV was controlled by quantitative trait loci (QTLs). Three new QTLs for RBSDV resistance were identified in this study, i.e., qRBSDV-3, qRBSDV-10 and qRBSDV-11. The LOD scores of qRBSDV-3, qRBSDV-10 and qRBSDV-11 were 4.07, 2.24 and 2.21, accounting for 17.5%, 0.3% and 12.4% of the total phenotypic variation, respectively. All the resistance loci identified in this study were associated with virus resistance genes. The alleles for enhancing resistance on chromosomes 3 and 11 originated from Tetep, whereas the other allele on chromosome 10 originated from a susceptible parent. The identified new resistance QTLs in this study are useful resources for efficiently breeding resistant rice cultivars to RBSDV. PMID:26198760

  19. The c-terminus of wheat streak mosaic virus coat protein is involved in differential infection of wheat and maize through host-specific long-distance transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multifunctional viral coat proteins (CPs) play important roles in the virus life-cycle. The CP determinants and mechanisms involved in extension of host range of monocot-infecting viruses are poorly understood. The role of the C-terminal region of Wheat streak mosaic virus (WSMV) CP in virus transpo...

  20. Role of Dehydrodiferulates in Maize Resistance to Pests and Diseases

    PubMed Central

    Santiago, Rogelio; Malvar, Rosa A.

    2010-01-01

    Phenolic esters have attracted considerable interest due to the potential they offer for peroxidase catalysed cross-linking of cell wall polysaccharides. Particularly, feruloyl residues undergo radical coupling reactions that result in cross-linking (intra-/intermolecular) between polysaccharides, between polysaccharides and lignin and, between polysaccharides and proteins. This review addresses for the first time different studies in which it is established that cross-linking by dehydrodiferulates contributes to maize’s defences to pests and diseases. Dehydrodiferulate cross-links are involved in maize defence mechanisms against insects such as the European, Mediterranean, and tropical corn borers and, storage pest as the maize weevil. In addition, cross-links are also discussed to be involved in genetic resistance of maize to fungus diseases as Gibberella ear and stalk rot. Resistance against insects and fungus attending dehydrodiferulates could go hand in hand. Quantitative trait loci mapping for these cell wall components could be a useful tool for enhancing resistance to pest and diseases in future breeding programs. PMID:20386661

  1. Development of VNTR Markers to Assess Genetic Diversity of Mycosphaerella Fijiensis, the Causal Agent of Black Leaf Streak Disease in Bananas (Musa spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycosphaerella fijiensis is the causal agent of black leaf streak (BLS) disease in bananas. This pathogen threatens global banana production as the main export cultivars are highly susceptible. As a consequence, commercial banana plantations must be protected chemically with fungicides; up to 40 app...

  2. Variable Number of Tandem Repeat Markers in the Genome Sequence of Mycosphaerella Fijiensis, the Causal Agent of Black Leaf Streak Disease of Banana (Musa spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycosphaerella fijiensis, the causal agent of banana leaf streak disease (commonly known as black Sigatoka), is the most devastating pathogen attacking bananas (Musa spp). Recently the whole genome sequence of M. fijiensis became available. This sequence was screened for the presence of Variable Num...

  3. Development of a genetic linkage map of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in bananas (Musa spp.) using SSR and DArT markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycosphaerella fijiensis is the causal agent of black leaf streak (BLS) disease in bananas. This pathogen threatens global banana production as the main export cultivars are highly susceptible. As a consequence, commercial banana plantations must be protected chemically with fungicides; up to 40 app...

  4. Maize-Pathogen Interactions: An Ongoing Combat from a Proteomics Perspective

    PubMed Central

    Pechanova, Olga; Pechan, Tibor

    2015-01-01

    Maize (Zea mays L.) is a host to numerous pathogenic species that impose serious diseases to its ear and foliage, negatively affecting the yield and the quality of the maize crop. A considerable amount of research has been carried out to elucidate mechanisms of maize-pathogen interactions with a major goal to identify defense-associated proteins. In this review, we summarize interactions of maize with its agriculturally important pathogens that were assessed at the proteome level. Employing differential analyses, such as the comparison of pathogen-resistant and susceptible maize varieties, as well as changes in maize proteomes after pathogen challenge, numerous proteins were identified as possible candidates in maize resistance. We describe findings of various research groups that used mainly mass spectrometry-based, high through-put proteomic tools to investigate maize interactions with fungal pathogens Aspergillus flavus, Fusarium spp., and Curvularia lunata, and viral agents Rice Black-streaked Dwarf Virus and Sugarcane Mosaic Virus. PMID:26633370

  5. Black streak root rot of lentil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Black streak root rot of lentil is caused by the soil borne fungus Thielaviopsis basicola. The pathogen is widespread. The disease shows symptoms of black streaking on root, and stunted plants. The disease is favored by cool and moist weather. Management of the disease rely on avoiding fields wi...

  6. Developing maize germplasm lines with multiple insect and disease resistance and low aflatoxin contamination

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yield and quality losses caused BY insects, diseases, and mycotoxin contaminations are the critical impediments for maize production under warm climate. In order to develop maize germplasm lines with resistance to multiple insect pests and aflatoxin accumulation, a set of 13 reciprocal breeding cro...

  7. Screening for insect and disease resistance and aflatoxin accumulation in experimental maize hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to develop new maize germplasm lines with resistance to multiple insect pests, disease, and aflatoxin accumulation in temperate region, a set of new experimental hybrids was made using exotic tropical and subtropical maize inbred lines. The evaluation of these breeding crosses for insect a...

  8. The Dynamics and Environmental Influence on Interactions Between Cassava Brown Streak Disease and the Whitefly, Bemisia tabaci.

    PubMed

    Jeremiah, S C; Ndyetabula, I L; Mkamilo, G S; Haji, S; Muhanna, M M; Chuwa, C; Kasele, S; Bouwmeester, H; Ijumba, J N; Legg, J P

    2015-05-01

    Cassava brown streak disease (CBSD) is currently the most significant virus disease phenomenon affecting African agriculture. In this study, we report results from the most extensive set of field data so far presented for CBSD in Africa. From assessments of 515 farmers' plantings of cassava, incidence in the Coastal Zone of Tanzania (46.5% of plants; 87% of fields affected) was higher than in the Lake Zone (22%; 34%), but incidences for both zones were greater than previous published records. The whitefly vector, Bemisia tabaci, was more abundant in the Lake Zone than the Coastal Zone, the reverse of the situation reported previously, and increased B. tabaci abundance is driving CBSD spread in the Lake Zone. The altitudinal "ceiling" previously thought to restrict the occurrence of CBSD to regions <1,000 masl has been broken as a consequence of the greatly increased abundance of B. tabaci in mid-altitude areas. Among environmental variables analyzed, minimum temperature was the strongest determinant of CBSD incidence. B. tabaci in the Coastal and Lake Zones responded differently to environmental variables examined, highlighting the biological differences between B. tabaci genotypes occurring in these regions and the superior adaptation of B. tabaci in the Great Lakes region both to cassava and low temperature conditions. Regression analyses using multi-country data sets could be used to determine the potential environmental limits of CBSD. Approaches such as this offer potential for use in the development of predictive models for CBSD, which could strengthen country- and continent-level CBSD pandemic mitigation strategies. PMID:25585059

  9. Fumonisin biomarkers in maize eaters and implications for human disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize is the predominant food source contaminated by fumonisins and this has particular health risks for communities consuming maize as a staple diet. The main biochemical effect of fumonisins is the inhibition of ceramide biosynthesis causing an increase in sphingoid bases and sphingoid base 1-pho...

  10. A Biochemical Phenotype for a Disease Resistance Gene of Maize.

    PubMed Central

    Meeley, RB; Johal, GS; Briggs, SP; Walton, JD

    1992-01-01

    In maize, major resistance to the pathogenic fungus Cochliobolus (Helminthosporium) carbonum race 1 is determined by the dominant allele of the nuclear locus hm. The interaction between C. carbonum race 1 and maize is mediated by a pathogen-produced, low molecular weight compound called HC-toxin. We recently described an enzyme from maize, called HC-toxin reductase, that inactivates HC-toxin by pyridine nucleotide-dependent reduction of an essential carbonyl group. We now report that this enzyme activity is detectable only in extracts of maize that are resistant to C. carbonum race 1 (genotype Hm/Hm or Hm/hm). In several genetic analyses, in vitro HC-toxin reductase activity was without exception associated with resistance to C. carbonum race 1. The results indicate that detoxification of HC-toxin is the biochemical basis of Hm-specific resistance of maize to infection by C. carbonum race 1. PMID:12297630

  11. Microchannel plate streak camera

    DOEpatents

    Wang, Ching L.

    1989-01-01

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 KeV x-rays.

  12. Microchannel plate streak camera

    DOEpatents

    Wang, C.L.

    1989-03-21

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras is disclosed. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1,000 KeV x-rays. 3 figs.

  13. Microchannel plate streak camera

    DOEpatents

    Wang, C.L.

    1984-09-28

    An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (uv to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 keV x-rays.

  14. Co-infection and disease severity of Ohio Maize dwarf mosaic virus and Maize chlorotic dwarf virus strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two major maize viruses have been reported in the United States: Maize dwarf mosaic virus (MDMV) and Maize chlorotic dwarf virus (MCDV). These viruses co-occur in regions where maize is grown such that co-infections are likely. Co-infection of different strains of MCDV is also observed frequently...

  15. Identification and fine-mapping of a QTL, qMrdd1, that confers recessive resistance to maize rough dwarf disease

    PubMed Central

    2013-01-01

    Background Maize rough dwarf disease (MRDD) is a devastating viral disease that results in considerable yield losses worldwide. Three major strains of virus cause MRDD, including maize rough dwarf virus in Europe, Mal de Río Cuarto virus in South America, and rice black-streaked dwarf virus in East Asia. These viral pathogens belong to the genus fijivirus in the family Reoviridae. Resistance against MRDD is a complex trait that involves a number of quantitative trait loci (QTL). The primary approach used to minimize yield losses from these viruses is to breed and deploy resistant maize hybrids. Results Of the 50 heterogeneous inbred families (HIFs), 24 showed consistent responses to MRDD across different years and locations, in which 9 were resistant and 15 were susceptible. We performed trait-marker association analysis on the 24 HIFs and found six chromosomal regions which were putatively associated with MRDD resistance. We then conducted QTL analysis and detected a major resistance QTL, qMrdd1, on chromosome 8. By applying recombinant-derived progeny testing to self-pollinated backcrossed families, we fine-mapped the qMrdd1 locus into a 1.2-Mb region flanked by markers M103-4 and M105-3. The qMrdd1 locus acted in a recessive manner to reduce the disease-severity index (DSI) by 24.2–39.3%. The genetic effect of qMrdd1 was validated using another F6 recombinant inbred line (RIL) population in which MRDD resistance was segregating and two genotypes at the qMrdd1 locus differed significantly in DSI values. Conclusions The qMrdd1 locus is a major resistance QTL, acting in a recessive manner to increase maize resistance to MRDD. We mapped qMrdd1 to a 1.2-Mb region, which will enable the introgression of qMrdd1-based resistance into elite maize hybrids and reduce MRDD-related crop losses. PMID:24079304

  16. Indirect selection for resistance to ear rot and leaf diseases in maize lines using biplots.

    PubMed

    Pereira, G S; Camargos, R B; Balestre, M; Von Pinho, R G; C Melo, W M

    2015-01-01

    Leaf disease and ear rot have caused reductions in maize yield in Brazil and other producer countries. Therefore, the aims of this study were to analyze the association between husked ear yield and the severity of maize white spot, gray leaf spot, helminthosporium, and ear rot caused by Fusarium verticillioides and Diplodia maydis using biplots in a mixed-model approach. The responses of 238 lines introduced to Brazil and four controls were evaluated using an incomplete block design with three replicates in two locations: Lavras and Uberlândia, Minas Gerais, Brazil. Two experiments were conducted in each location, one with F. verticillioides and the other with D. maydis. The mixed models elucidated the relationship between yield, leaf disease, and ear disease. Significant genotype x environment and genotype x pathogen interactions were observed. In conclusion, husked ear yield is more associated with ear rot than with the leaf diseases evaluated, justifying the indirect selection for resistance to kernel rot in maize-F. verticillioides and maize-D. maydis pathosystems by yield evaluation. PMID:26400335

  17. Crater and Wind Streak

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-461, 23 August 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater with a bright wind streak in southern Acidalia Planitia. The streak is mostly likely a very thin coating of dust. The orientation of the streak indicates that the winds responsible for its formation and maintenance came from the northeast (upper right) and blew toward the lower left (southwest). The crater is located near 24.8oN, 39.1oW. The image covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  18. Crater with Streak

    NASA Technical Reports Server (NTRS)

    2005-01-01

    20 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater in the Memnonia region of Mars, around which has formed a wind streak. The bright streak is in the lee of the crater -- that is, it is on the crater's down-wind side. Thus, the winds responsible for the streak blew from the southeast (lower right).

    Location near: 6.7oS, 141.4oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  19. Maize Prolamins Could Induce a Gluten-Like Cellular Immune Response in Some Celiac Disease Patients

    PubMed Central

    Ortiz-Sánchez, Juan P.; Cabrera-Chávez, Francisco; Calderón de la Barca, Ana M.

    2013-01-01

    Celiac disease (CD) is an autoimmune-mediated enteropathy triggered by dietary gluten in genetically prone individuals. The current treatment for CD is a strict lifelong gluten-free diet. However, in some CD patients following a strict gluten-free diet, the symptoms do not remit. These cases may be refractory CD or due to gluten contamination; however, the lack of response could be related to other dietary ingredients, such as maize, which is one of the most common alternatives to wheat used in the gluten-free diet. In some CD patients, as a rare event, peptides from maize prolamins could induce a celiac-like immune response by similar or alternative pathogenic mechanisms to those used by wheat gluten peptides. This is supported by several shared features between wheat and maize prolamins and by some experimental results. Given that gluten peptides induce an immune response of the intestinal mucosa both in vivo and in vitro, peptides from maize prolamins could also be tested to determine whether they also induce a cellular immune response. Hypothetically, maize prolamins could be harmful for a very limited subgroup of CD patients, especially those that are non-responsive, and if it is confirmed, they should follow, in addition to a gluten-free, a maize-free diet. PMID:24152750

  20. Plant–pathogen microevolution: Molecular basis for the origin of a fungal disease in maize

    PubMed Central

    Multani, D. S.; Meeley, R. B.; Paterson, A. H.; Gray, J.; Briggs, S. P.; Johal, G. S.

    1998-01-01

    A new and severe disease of maize caused by a previously unknown fungal pathogen, Cochliobolus carbonum race 1, was first described in 1938. The molecular events that led to the sudden appearance of this disease are described in this paper. Resistance to C. carbonum race 1 was found to be widespread in maize and is conferred by a pair of unlinked duplicate genes, Hm1 and Hm2. Here, we demonstrate that resistance is the wild-type condition in maize. Two events, a transposon insertion in Hm1 and a deletion in Hm2, led to the loss of resistance, resulting in the origin of a new disease. None of the other plant species tested is susceptible to C. carbonum race 1, and they all possess candidate genes with high homology to Hm1 and Hm2. In sorghum and rice, these homologs map to two chromosomal regions that are syntenic with the maize Hm1 and Hm2 loci, indicating that they are related to the maize genes by vertical descent. These results suggest that the Hm-encoded resistance is of ancient origin and probably is conserved in all grasses. PMID:9465077

  1. STREAK damping. Technical report

    SciTech Connect

    Baker, J.; Peyton, S.; Freiberg, H.

    1989-12-01

    This report documents a study aimed at improving the damping in STREAK. A form and value for an artificial viscosity is recommended which appears to control ringing and overshoots without overdamping.

  2. Wind Streak Changes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    2 September 2004 This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows changes in dark wind streak patterns that occurred between 5 April 1999 (image M00-00534) and 17 August 2004 (image R20-00901). Unlike the spaghetti-like streak patterns made by dust devils, these streaks all begin on their upwind ends as tapered forms that fan outward in the downwind direction, and they all indicate winds that blew from the same direction. In both cases, winds blew from the southeast (lower right) toward the northwest (upper left). These streaks and the small pedestal craters found among them occur in the Memnonia region of Mars near 5.9oS, 162.2oW. The 400 meter scale bar is about 437 yards long. Sunlight illuminates each scene from the upper left.

  3. Daedalia Wind Streak

    NASA Technical Reports Server (NTRS)

    2004-01-01

    21 January 2004 This January 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark wind streak in the lee of a small meteor impact crater in Daedalia Planum. The dominant winds responsible for this streak blew from the east (right). This picture is located near 17.1oS, 138.8oW, and covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the left.

  4. Wind Streak and Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    23 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak developed in the lee of a meteor impact crater in western Daedalia Planum. The dominant winds responsible for the streak blew from the bottom/lower right (southeast). The image is located near 9.9oS, 144.9oW. Sunlight illuminates the scene from the lower left; the picture covers an area 3 km (1.9 mi) wide.

  5. A predicted protein interactome identifies conserved global networks and disease resistance subnetworks in maize

    PubMed Central

    Musungu, Bryan; Bhatnagar, Deepak; Brown, Robert L.; Fakhoury, Ahmad M.; Geisler, Matt

    2015-01-01

    Interactomes are genome-wide roadmaps of protein-protein interactions. They have been produced for humans, yeast, the fruit fly, and Arabidopsis thaliana and have become invaluable tools for generating and testing hypotheses. A predicted interactome for Zea mays (PiZeaM) is presented here as an aid to the research community for this valuable crop species. PiZeaM was built using a proven method of interologs (interacting orthologs) that were identified using both one-to-one and many-to-many orthology between genomes of maize and reference species. Where both maize orthologs occurred for an experimentally determined interaction in the reference species, we predicted a likely interaction in maize. A total of 49,026 unique interactions for 6004 maize proteins were predicted. These interactions are enriched for processes that are evolutionarily conserved, but include many otherwise poorly annotated proteins in maize. The predicted maize interactions were further analyzed by comparing annotation of interacting proteins, including different layers of ontology. A map of pairwise gene co-expression was also generated and compared to predicted interactions. Two global subnetworks were constructed for highly conserved interactions. These subnetworks showed clear clustering of proteins by function. Another subnetwork was created for disease response using a bait and prey strategy to capture interacting partners for proteins that respond to other organisms. Closer examination of this subnetwork revealed the connectivity between biotic and abiotic hormone stress pathways. We believe PiZeaM will provide a useful tool for the prediction of protein function and analysis of pathways for Z. mays researchers and is presented in this paper as a reference tool for the exploration of protein interactions in maize. PMID:26089837

  6. Genetic analysis of resistance to six virus diseases in a multiple virus-resistant maize inbred line

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Virus diseases in maize can cause severe yield reductions that threaten crop production and food supplies in some regions of the world. Genetic resistance to different viruses has been characterized in maize populations under diverse environments and screening techniques, and resistance loci have be...

  7. Frosty Wind Streaks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-532, 2 November 2003

    As seasonal polar frosts sublime away each spring, winds may re-distribute some of the frost or move sediment exposed from beneath the frost. This action creates ephemeral wind streaks that can be used by scientists seeking to study the local circulation of the martian [missing text] surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of wind streaks created in subliming carbon dioxide frost. These dark streaks appear to conform to the shape of the slopes on which they occur, suggesting that slope winds play a dominant role in creating and orienting these streaks. This picture is located near 73.8oS, 305.7oW. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide. Winds responsible for the streaks generally blew from the bottom/right (south/southeast) toward the top/upper left (north/northwest).

  8. Endophytic Fusarium verticillioides reduces disease severity caused by Ustilago maydis on maize.

    PubMed

    Lee, Keunsub; Pan, Jean J; May, Georgiana

    2009-10-01

    Endophytic fungi represent diverse taxa that inhabit plant hosts without causing disease symptoms. We used endophytic isolates of Fusarium verticillioides (Sacc.) Nirenberg to understand how endophytic fungi interact with pathogens, in this case, the corn smut pathogen, Ustilago maydis DC (Corda). Endophytic F. verticillioides strains were inoculated onto maize seedlings before, simultaneously, or after inoculation with U. maydis, and the effects on smut disease severity and on plant growth were assessed. When F. verticillioides is simultaneously coinoculated with U. maydis, smut disease severity is significantly decreased and plant growth is increased, compared with other treatments. Controls show that F. verticillioides by itself does not have measurable effects on plant growth. Together, our results suggest that a commonly occurring fungal endophyte on maize, F. verticillioides, ameliorates the effects of a host-specific pathogen, U. maydis, by interfering with the early infection process and limiting disease development, resulting in increased plant growth. PMID:19694816

  9. Huygens Wind Streak

    NASA Technical Reports Server (NTRS)

    2005-01-01

    19 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the results of wind action on the floor of the giant martian impact basin, Huygens. The large crater in this image has a wind streak on its lee side, pointing toward the lower right (southeast). Usually, a light-toned wind streak behind a crater on Mars will be composed of a thin veneer of dust that the wind was not able to erode because it was protected by the presence of the crater's raised rims. In this case, the streak is caused by something different -- by the fact that dark, windblown sand has not been able to accumulate behind the crater.

    Location near: 13.0oS, 303.7oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

  10. Elysium Mons Wind Streak

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-556, 26 November 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wind streak formed behind a meteor impact crater on the lower north flank of the volcano, Elysium Mons. Winds blow down the volcano slope, toward the northeast (toward upper right), causing a tail of uneroded dust to be captured behind the crater. Thin, filamentary dark streaks (resembling pencil scratches in this image) can be seen on the surface of the bright wind streak; these may have formed by disruption of surface dust by passing dust devils. This picture is located near 27.7oN, 212.7oW. The image covers an area 3 km (1.9 mi) wide, and is illuminated by sunlight from the left.

  11. Polar Dust Devil Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    30 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of dunes in the martian north polar region is important because it shows one of the highest northern latitude views of streaks thought to be made by passing dust devils. The dark, thin, filamentary streaks on the dunes and on the adjacent plains were probably formed by dust devils. The dunes occur near 76.6oN, 62.7oW. Dust devil streaks are observed on Mars at very high latitudes, such as this, all the way down to the equator. They are also seen at all elevations, from the deepest parts of the Hellas Basin to the summit of Olympus Mons. This picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  12. Plant-Plant-Microbe Mechanisms Involved in Soil-Borne Disease Suppression on a Maize and Pepper Intercropping System

    PubMed Central

    Mei, Xinyue; Liao, Jingjing; Ding, Xupo; Deng, Weiping; Fan, Limin; He, Xiahong; Vivanco, Jorge M.; Li, Chengyun; Zhu, Youyong; Zhu, Shusheng

    2014-01-01

    Background Intercropping systems could increase crop diversity and avoid vulnerability to biotic stresses. Most studies have shown that intercropping can provide relief to crops against wind-dispersed pathogens. However, there was limited data on how the practice of intercropping help crops against soil-borne Phytophthora disease. Principal Findings Compared to pepper monoculture, a large scale intercropping study of maize grown between pepper rows reduced disease levels of the soil-borne pepper Phytophthora blight. These reduced disease levels of Phytophthora in the intercropping system were correlated with the ability of maize plants to form a “root wall” that restricted the movement of Phytophthora capsici across rows. Experimentally, it was found that maize roots attracted the zoospores of P. capsici and then inhibited their growth. When maize plants were grown in close proximity to each other, the roots produced and secreted larger quantities of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) and 6-methoxy-2-benzoxazolinone (MBOA). Furthermore, MBOA, benzothiazole (BZO), and 2-(methylthio)-benzothiazole (MBZO) were identified in root exudates of maize and showed antimicrobial activity against P. capsici. Conclusions Maize could form a “root wall” to restrict the spread of P. capsici across rows in maize and pepper intercropping systems. Antimicrobe compounds secreted by maize root were one of the factors that resulted in the inhibition of P. capsici. These results provide new insights into plant-plant-microbe mechanisms involved in intercropping systems. PMID:25551554

  13. Expression of a rice chitinase gene in transgenic banana ('Gros Michel', AAA genome group) confers resistance to black leaf streak disease.

    PubMed

    Kovács, Gabriella; Sági, László; Jacon, Géraldine; Arinaitwe, Geofrey; Busogoro, Jean-Pierre; Thiry, Els; Strosse, Hannelore; Swennen, Rony; Remy, Serge

    2013-02-01

    Transgenic banana (Musa acuminata 'Gros Michel') integrating either of two rice chitinase genes was generated and its resistance to Black Leaf Streak disease caused by the fungus Mycosphaerella fijiensis was tested using a leaf disk bioassay. PCR screening indicated the presence of the hpt selectable marker gene in more than 90 % of the lines tested, whereas more than three quarters of the lines contained the linked rice chitinase gene resulting in a co-transformation frequency of at least 71.4 %. Further, a unique stable integration of the transgenes in each line revealed some false negative PCR results and the expected co-transformation frequency of 100 %. The transgene insert number per line ranged from 1 to 5 and single transgene insert lines (25 % of all) were identified. Considerable delay in disease development (up to 63 days post-incoculation) over a monitoring period of 108 days occurred in nine lines with extracellularly targeted chitinase out of 17 transgenic lines tested and their necrotic leaf area decreased by 73-94 % compared to the untransformed susceptible control line. Finally, correlation between symptom development and rice chitinase expression was confirmed in two lines by Western analysis. The potential of rice chitinase genes to enhance resistance against M. fijiensis in banana was demonstrated as well as the usefulness of the leaf disk bioassay for early disease screening in transgenic banana lines. PMID:22791138

  14. Wind Streaks Among Flows

    NASA Technical Reports Server (NTRS)

    2004-01-01

    17 December 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark wind streaks formed by removal of a thin veneer of bright dust covering small craters and lava flow surfacesnorthwest of Olympus Mons near 28.4oN, 129.8oW. Streak orientations indicate that the responsible winds blew from the east/southeast (right/lower right) toward the west/northwest (left/upper left). The image covers an area about 3 km (1.9 mi) wide. Sunlight illuminates thescene from the lower left.

  15. Devil-Streaked Plain

    NASA Technical Reports Server (NTRS)

    2006-01-01

    19 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark streaks on a plain south of the giant impact basin, Hellas Planitia. The streaks map the routes traveled by dozens of individual southern spring and early summer dust devils.

    Location near: 68.4oS, 296.1oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  16. Streak camera receiver definition study

    NASA Technical Reports Server (NTRS)

    Johnson, C. B.; Hunkler, L. T., Sr.; Letzring, S. A.; Jaanimagi, P.

    1990-01-01

    Detailed streak camera definition studies were made as a first step toward full flight qualification of a dual channel picosecond resolution streak camera receiver for the Geoscience Laser Altimeter and Ranging System (GLRS). The streak camera receiver requirements are discussed as they pertain specifically to the GLRS system, and estimates of the characteristics of the streak camera are given, based upon existing and near-term technological capabilities. Important problem areas are highlighted, and possible corresponding solutions are discussed.

  17. Acyl-homoserine lactones produced by Pantoea sp. isolated from the "maize white spot" foliar disease.

    PubMed

    Pomini, Armando M; Paccola-Meirelles, Luzia D; Marsaioli, Anita J

    2007-02-21

    The "maize white spot" foliar disease is a problem of increasing importance to Brazilian maize crops. A bacterium isolated from water-soaked lesions from infected maize leaves was pathogenic in biological assays in vivo. It was identified as a Gram-negative, nonsporulating, facultative anaerobic bacterium, belonging to the genus Pantoea. Chemical study of the extracts from bacterial cultivation media allowed the identification of (S)-(-)-N-butanoyl-homoserine lactone and trace amounts of N-hexanoyl-homoserine lactone, widely recognized quorum-sensing signaling substances employed in cell-to-cell communication systems. The absolute configuration of natural (S)-(-)-N-butanoyl-homoserine lactone was determined by gas chromatography-flame ionization detection with a chiral stationary phase and by comparison of circular dichroism spectroscopic data with enantiopure synthetic substances. Biological evaluations with reporter Agrobacterium tumefaciens NTL4(pZLR4) were carried out with synthetic and natural products and also with extracts from maize leaves contaminated with the isolated bacterium, as well as from healthy leaves. PMID:17256964

  18. Distribution of disease symptoms and mycotoxins in maize ears infected by Fusarium culmorum and Fusarium graminearum.

    PubMed

    Oldenburg, Elisabeth; Ellner, Frank

    2015-08-01

    Red ear rot an important disease of maize cultivated in Europe is caused by toxigenic Fusarium species like Fusarium graminearum and Fusarium culmorum. To get detailed information on the time course of the infection process leading to the accumulation of Fusarium mycotoxins in maize ears, a field study was conducted over 2 years with two maize varieties, which were inoculated with F. culmorum or F. graminearum isolates at the stage of female flowering. Every fortnight after inoculation, infection and contamination progress in the ears was followed by visually evaluating disease signs and analysing Fusarium toxin concentrations in the infected ear tissues. In principle, infection and mycotoxin distribution were similar in respect of pathogens, varieties, and years. External infection symptoms showing some small pale or brown-marbled kernels with dark brown pedicels were mainly seen at the ear tip, whereas internal infection symptoms on the rachis were much more pronounced and spread in the upper half showing greyish brownish or pink discoloration of the pith. Well correlated with disease symptoms, a top-down gradient from high to low toxin levels within the ear with considerably higher concentrations in the rachis compared with the kernels was observed. It is suggested that both Fusarium pathogens primarily infect the rachis from the tip toward the bottom, whereas the kernels are subsequently infected via the rachillae connected to the rachis. A special focus on the pronounced disease symptoms visible in the rachis may be an approach to improve the evaluation of maize-genotype susceptibility against red ear rot pathogens. It has to be underlined that the accumulation of Fusarium mycotoxins in the rachis greatly accelerated 6 weeks after inoculation; therefore, highest contamination risk is indicated for feedstuffs containing large amounts of rachis (e.g., corn cob mix), especially when cut late in growing season. PMID:25904523

  19. Oxidative stress response of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in banana plants, to hydrogen peroxide and paraquat.

    PubMed

    Beltrán-García, Miguel J; Manzo-Sanchez, Gilberto; Guzmán-González, Salvador; Arias-Castro, Carlos; Rodríguez-Mendiola, Martha; Avila-Miranda, Martin; Ogura, Tetsuya

    2009-07-01

    Mycosphaerella fijiensis causes black leaf streak disease in banana and plantain. This fungus is usually attacked by reactive oxygen species secreted by the plant or during exposure to fungicide, however, little is known about the antioxidant response of the fungus. In this study, mycelia were observed to totally decompose 30 mmol/L of hydrogen peroxide (H2O2) within 120 min, liberating oxygen bubbles, and also to survive in concentrations as high as 100 mmol/L H2O2. The oxidative stress responses to H2O2, paraquat, and hydroquinone were characterized in terms of the activities of catalase and superoxide dismutase (SOD). Two active catalase bands were seen in native PAGE induced by H2O2. Band I had monofunctional activity and band II had bifunctional catalase-peroxidase activity. Two isozymes of SOD, distinguishable by their cyanide sensitivity, were found; CuZnSOD was the main one. The combination of H2O2 and 3-aminotriazole reduced the accumulation of biomass up to 40% compared with exposure to H2O2 alone, suggesting that catalase is important for the rapid decomposition of H2O2 and has a direct bearing on cell viability. The results also suggest that the superoxide anion formed through the redox of paraquat and hydroquinone has a greater effect than H2O2 on the cellular viability of M. fijiensis. PMID:19767862

  20. Craters and Streaks

    NASA Technical Reports Server (NTRS)

    2006-01-01

    1 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows two impact craters of nearly equal size, plus their associated wind streaks. These occur in far eastern Chryse Planitia. The wind streaks point toward the southwest (lower left), indicating that the responsible winds blew from the northeast. One of the two craters is shallower than the other, and has a suite of large, windblown ripples on its floor. The shallower crater with the ripples is probably older than the other, deeper crater.

    Location near: 20.6oN, 30.1oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  1. Dust Devil Streaks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    27 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of dark streaks created by spring and summer dust devil activity in Argyre Planitia.

    Location near: 64.9oS, 8.3oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  2. The development and application of a Dot-ELISA assay for diagnosis of southern rice black-streaked dwarf disease in the field.

    PubMed

    Wang, Zhenchao; Yu, Dandan; Li, Xiangyang; Zeng, Mengjiao; Chen, Zhuo; Bi, Liang; Liu, Jiaju; Jin, Linhong; Hu, Deyu; Yang, Song; Song, Baoan

    2012-01-01

    Outbreaks of the southern rice black-streaked dwarf virus (SRBSDV) have caused significant crop losses in southern China in recent years, especially in 2010. There are no effective, quick and practicable methods for the diagnosis of rice dwarf disease that can be used in the field. Traditional reverse transcription-polymerase chain reaction (RT-PCR) methodology is accurate but requires expensive reagents and instruments, as well as complex procedures that limit its applicability for field tests. To develop a sensitive and reliable assay for routine laboratory diagnosis, a rapid dot enzyme-linked immunosorbent assay (dot-ELISA) method was developed for testing rice plants infected by SRBSDV. Based on anti-SRBSDV rabbit antiserum, this new dot-ELISA was highly reliable, sensitive and specific toward SRBSDV. The accuracy of two blotting media, polyvinylidene fluoride membrane (PVDF membrane) and nitrocellulose filter membrane (NC membrane), was compared. In order to facilitate the on-site diagnosis, three county laboratories were established in Shidian (Yunnan province), Jianghua (Hunan Province) and Libo (Guizhou province). Suspected rice cases from Shidian, Yuanjiang and Malipo in Yunnan province were tested and some determined to be positive for SRBSDV by the dot-ELISA and confirmed by the One Step RT-PCR method. To date, hundreds of suspected rice samples collected from 61 districts in southwestern China have been tested, among which 55 districts were found to have rice crops infected by SRBSDV. Furthermore, the test results in the county laboratories showed that Libo, Dehong (suspected samples were sent to Shidian) and Jianghua were experiencing a current SRBSDV outbreak. PMID:22355457

  3. Triton's streaks as windblown dust

    NASA Technical Reports Server (NTRS)

    Sagan, Carl; Chyba, Christopher

    1990-01-01

    Explanations for the surface streaks observed by Voyager 2 on Triton's southern hemisphere are discussed. It is shown that, despite Triton's tenuous atmosphere, low-cohesion dust trains with diameters of about 5 micron or less may be carried into suspension by aeolian surface shear stress, given expected geostrophic wind speeds of about 10 m/s. For geyser-like erupting dust plumes, it is shown that dust-settling time scales and expected wind velocities can produce streaks with length scales in good agreement with those of the streaks. Thus, both geyserlike eruptions or direct lifting by surface winds appear to be viable mechanisms for the origin of the streaks.

  4. Daedalia Planum Wind Streak

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-332, 16 April 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a complex streak formed by deposition and erosion of sediment by wind in the lee of an impact crater in western Daedalia Planum. The winds needed to create this feature blew from the southeast (from the lower right). The picture covers an area 3 km (1.9 mi) wide near 10.1oS, 133.7oW. Sunlight illuminates the scene from the upper left.

  5. Bright Devil Streaks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    4 March 2005 In honor of Giovanni V. Schiaparelli's 170th birthday, we present this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image showing light-toned dust devil streaks on the southern floor of Schiaparelli Crater.

    Location near: 5.3oS, 343.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  6. Bright Streak on Amalthea

    NASA Technical Reports Server (NTRS)

    2000-01-01

    These two images of Jupiter's small, irregularly shaped moon Amalthea, obtained by the camera onboard NASA's Galileo spacecraft in August 1999(left) and November 1999 (right), form a 'stereo pair' that helps scientists determine this moon's shape and the topography of its surface features. Features as small as 3.8 kilometers (2.4 miles) across can be resolved in these images, making them among the highest-resolution images ever taken of Amalthea.

    The large impact crater visible in both images, near the right-hand edge of Amalthea's disk, is about 40 kilometers (about 29 miles) across; two ridges, tall enough to cast shadows, extend from the top of the crater in a V-shape reminiscent of a 'rabbit ears' television antenna. To the left of these ridges, in the top center portion of Amalthea's disk, is a second large impact crater similar in size to the first crater. To the left of this second crater is a linear 'streak' of relatively bright material about 50 kilometers (31 miles) long. In previous spacecraft images of Amalthea taken from other viewing directions, this bright feature was thought to be a small, round, bright 'spot' and was given the name Ida. These new images reveal for the first time that Ida is actually a long, linear 'streak.' This bright streak may represent material ejected during the formation of the adjacent impact crater, or it may just mark the crest of a local ridge. Other patches of relatively bright material can be seen elsewhere on Amalthea's disk, although none of these other bright spots has Ida's linear shape.

    In both images, sunlight is coming from the left and north is approximately up. Note that the north pole of Amalthea is missing in the right-hand image (it was cut off by the edge of the camera frame). The bright streak, Ida, is on the side of the moon that faces permanently away from Jupiter, and the crater near the right-hand edge of the disk is in the center of Amalthea's leading side (the side of the moon that 'leads

  7. Streaking into Middle School Science: The Dell Streak Pilot Project

    ERIC Educational Resources Information Center

    Austin, Susan Eudy

    2012-01-01

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the…

  8. Mapping QTL conferring resistance in maize to gray leaf spot disease caused by Cercospora zeina

    PubMed Central

    2014-01-01

    Background Gray leaf spot (GLS) is a globally important foliar disease of maize. Cercospora zeina, one of the two fungal species that cause the disease, is prevalent in southern Africa, China, Brazil and the eastern corn belt of the USA. Identification of QTL for GLS resistance in subtropical germplasm is important to support breeding programmes in developing countries where C. zeina limits production of this staple food crop. Results A maize RIL population (F7:S6) from a cross between CML444 and SC Malawi was field-tested under GLS disease pressure at five field sites over three seasons in KwaZulu-Natal, South Africa. Thirty QTL identified from eleven field trials (environments) were consolidated to seven QTL for GLS resistance based on their expression in at least two environments and location in the same core maize bins. Four GLS resistance alleles were derived from the more resistant parent CML444 (bin 1.10, 4.08, 9.04/9.05, 10.06/10.07), whereas the remainder were from SC Malawi (bin 6.06/6.07, 7.02/7.03, 9.06). QTLs in bin 4.08 and bin 6.06/6.07 were also detected as joint QTLs, each explained more than 11% of the phenotypic variation, and were identified in four and seven environments, respectively. Common markers were used to allocate GLS QTL from eleven previous studies to bins on the IBM2005 map, and GLS QTL “hotspots” were noted. Bin 4.08 and 7.02/7.03 GLS QTL from this study overlapped with hotspots, whereas the bin 6.06/6.07 and bin 9.06 QTLs appeared to be unique. QTL for flowering time (bin 1.07, 4.09) in this population did not correspond to QTL for GLS resistance. Conclusions QTL mapping of a RIL population from the subtropical maize parents CML444 and SC Malawi identified seven QTL for resistance to gray leaf spot disease caused by C. zeina. These QTL together with QTL from eleven studies were allocated to bins on the IBM2005 map to provide a basis for comparison. Hotspots of GLS QTL were identified on chromosomes one, two, four, five and

  9. Light and Dark Slope Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    21 July 2004 Dark slope streaks are a common feature on slopes thickly-mantled by dust, especially in the Tharsis, Arabia, and western Amazonis regions of Mars. Less common are light-toned slope streaks, which often occur in the same area as dark streaks. They are most common in Arabia Terra, and some are shown in this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image. Slope streaks are probably the result of sudden avalanches of extremely dry dust. The behavior of the avalanching dust is somewhat fluid-like, and new streaks have been observed to form over intervals of a few months to a Mars year. This image is located near 13.4oN, 340.3oW, and covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  10. Stolbur Phytoplasma Transmission to Maize by Reptalus panzeri and the Disease Cycle of Maize Redness in Serbia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize redness (MR), induced by stolbur phytoplasma (Candidatus Phytoplasma solani, subgroup 16SrXII-A), is characterized by midrib, leaf and stalk reddening and abnormal ear development. MR has been reported from Serbia, Romania and Bulgaria for 50 years, and recent epiphytotics reduced yields by 4...

  11. Cerberus Wind Streaks

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 6 May 2002) The Science Cerberus is a dark region on Mars that has shrunk down from a continuous length of about 1000 km to roughly three discontinuous spots a few 100 kms in length in less than 20 years. There are two competing processes at work in the Cerberus region that produce the bright and dark features seen in this THEMIS image. Bright dust settles out of the atmosphere, especially after global dust storms, depositing a layer just thick enough to brighten the dark surfaces. Deposition occurs preferentially in the low wind 'shadow zones' within craters and downwind of crater rims, producing the bright streaks. The direction of the streaks clearly indicates that the dominant winds come from the northeast. Dust deposition would completely blot out the dark areas if it were not for the action of wind-blown sand grains scouring the surface and lifting the dust back into the atmosphere. Again, the shadow zones are protected from the blowing sand, preserving the bright layer of dust. Also visible in this image are lava flow features extending from the flanks of the huge Elysium volcanoes to the northwest. Two shallow channels and a raised flow lobe are just barely discernable. The lava channel in the middle of the image crosses the boundary of the bright and dark surfaces without any obvious change in its morphology. This demonstrates that the bright dust layer is very thin in this location, perhaps as little as a few millimeters. The Story Mars is an ever-changing land of spectacular contrasts. This THEMIS image shows the Cerberus region of Mars, a dark area located near the Elysium volcanoes and fittingly named after the three-headed, dragon-tailed dog who guards the door of the underworld. Two opposing processes are at work here: a thin layer of dust falling from the atmosphere and/or dust storms creating brighter surface areas (e.g. the top left portion of this image) and dust being scoured away by the action of the Martian wind disturbing the sand

  12. Impact of Cell Wall Composition on Maize Resistance to Pests and Diseases

    PubMed Central

    Santiago, Rogelio; Barros-Rios, Jaime; Malvar, Rosa A.

    2013-01-01

    In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among the same plant species, different tissues or even the same tissue at different developmental stages. Thus, it is important to highlight that the role of the cell wall components needs to be tested in diverse genotypes and specific tissues where the feeding or attacking by the pathogen takes place. Understanding the role of cell wall constituents as defense mechanisms may allow modifications of crops to withstand pests and diseases. PMID:23535334

  13. The genetic basis of flecking and its relationship to disease resistance in the IBM maize mapping population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flecking is defined as a mild, often environmentally-dependent lesion phenotype observed on the leaves of several commonly used maize inbred lines. Anecdotal evidence suggests a link between flecking and enhanced broad-spectrum disease resistance. Neither the genetic basis underlying flecking nor ...

  14. Disruption of ceramide biosynthesis and accumulation of sphingoid bases and sphingoid base 1-phosphates: A mechanism for Fusarium verticillioides effects in maize-seedling disease.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In sweet corn at the seedling and seed maturation stages, Fusarium can be a serious field problem. The fungus Fusarium verticillioides infects maize and produces fumonisins, inhibitors of ceramide synthase. To determine the role of fumonisins in maize seedling disease, seeds were inoculated with fu...

  15. Comparison of Streak Tube Performance

    SciTech Connect

    Lerche, R A; Andrews, D S; Bell, P M; Griffiths, R L; Huey, A W; McDonald, J W; de Dios, G V

    2004-11-04

    The performance of four streak tubes in six streak camera configurations is reported. Evaluations were made as part of a search for a streak tube to replace the obsolete RCA C73435 used in the ICF Program's optical streak cameras. Characteristics measured include linearity, spatial and temporal resolution, line-spread function, contrast transfer ratio (CTR), and dynamic range. Tubes evaluated are the RCA C73435, Photonis P510, Photek ST-Y, and Hamamatsu N8059. The RCA C73435 was evaluated in three camera configurations: large format CCD coupled directly to the streak tube, CCD directly coupled to an image intensifier tube (IIT), and the original configuration with a smaller CCD lens coupled to the IIT output. The Photonis and Photek tubes were characterized in configurations where they were directly coupled to large format CCDs. Optimum spatial resolution is achieved when the IIT is removed. Maximum dynamic range requires a configuration where a single photoelectron from the photocathode produces a signal that is {approx}5 times the CCD read noise. The Photonis P510 tube with the E2V CCD forms a well-optimized streak camera system.

  16. Characterization of Dark Streaks on Martian Slopes

    NASA Astrophysics Data System (ADS)

    Fenton, L. K.; Danielson, G. E.; Albee, A.; MGS MOC Science Team

    1998-09-01

    The narrow angle MOC images from the Mars Global Surveyor (MGS) show dozens of examples of dark streaks on Martian hillsides that may be indicative of fluid flow. In many cases multiple streaks seem to initiate from a narrow layer near the tops of steep slopes. They appear from these layers as narrow features that quickly broaden and then either remain the same width downhill or narrow and disappear. The largest streak observed to date is approximately 2 km in length and 100 m in width. MOLA data is not yet available to determine the slope down the length of the streaks. The lack of variation in brightness downhill and across the streaks shows that the formation of each streak occurred quickly. The streaks are widely distributed globally, but seem to be confined to layered materials. The streaks' characteristics show not only that the material forming them moved rapidly downslope but also that the streak material originated within the nearby bedrock. Change in brightness from one streak to another provides relative streak ages, assuming that dust infall causes an increase in streak albedo. The dark streaks are caused by a process that appears similar to fluid flow at the resolution of the MOC images. Possible causes of the streaks are water flow, lava flow, and debris flow. Our results are not yet conclusive as to the origins of the dark streaks, but we narrow the range of possible formation processes.

  17. Streak camera dynamic range optimization

    SciTech Connect

    Wiedwald, J.D.; Lerche, R.A.

    1987-09-01

    The LLNL optical streak camera is used by the Laser Fusion Program in a wide range of applications. Many of these applications require a large recorded dynamic range. Recent work has focused on maximizing the dynamic range of the streak camera recording system. For our streak cameras, image intensifier saturation limits the upper end of the dynamic range. We have developed procedures to set the image intensifier gain such that the system dynamic range is maximized. Specifically, the gain is set such that a single streak tube photoelectron is recorded with an exposure of about five times the recording system noise. This ensures detection of single photoelectrons, while not consuming intensifier or recording system dynamic range through excessive intensifier gain. The optimum intensifier gain has been determined for two types of film and for a lens-coupled CCD camera. We have determined that by recording the streak camera image with a CCD camera, the system is shot-noise limited up to the onset of image intensifier nonlinearity. When recording on film, the film determines the noise at high exposure levels. There is discussion of the effects of slit width and image intensifier saturation on dynamic range. 8 refs.

  18. Complete genome sequence of a novel badnavirus, banana streak IM virus.

    PubMed

    Geering, Andrew D W; Parry, Judith N; Thomas, John E

    2011-04-01

    In 1999, banana streak disease outbreaks occurred at two locations in Australia in new banana hybrids that were being screened for fusarium wilt resistance. Two different badnaviruses, banana streak GF virus and a newly discovered virus called banana streak IM virus (BSIMV), were detected in these plants. The complete nucleotide sequence of the BSIMV genome was determined and comprised 7768 nt. Three open reading frames were detected, the first beginning with a non-conventional start codon (CUG). A 55-nt repetition in the putative pregenomic RNA promoter was also identified. Phylogenetic analysis suggests that BSIMV is most closely related to banana streak VN virus. PMID:21347843

  19. The Rochester Optical Streak System

    NASA Astrophysics Data System (ADS)

    Jaanimagi, P. A.; Boni, R.; Keck, R. L.; Donaldson, W. R.; Meyerhofer, D. D.

    2004-11-01

    A modern, self-calibrating, remotely controlled streak camera platform capable of accepting a variety of different streak tubes has been developed. Our current systems include P510, P820, and PJX streak tubes with both S-1 and S-20 photocathodes. The input may be either fiber delivery or free-space propagation and is relayed to the photocathode with an achromatic Offner triplet. Calibration functions include autofocus of the input and electron optics, geometric distortion and flat-field correction, system gain, and linearity. The four remotely selectable sweep speeds are calibrated with an on-board optical comb generator. The recording system is a fiber-coupled back-illuminated CCD camera. We will present data illustrating the many features of the ROSS camera as applied to laser and plasma diagnostics. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

  20. Circular Scan Streak Tube Development

    NASA Technical Reports Server (NTRS)

    Nevin, S.

    1980-01-01

    A streak tube having circular scan was designed, built and tested. Continuous circular scan, easily derived from out of phase sine waves applied to the conventional deflection plates, permits the timing of pulses traveling long baselines. At the tube's output a circular array of 720 elements is scanned to provide 30 to 40 picosecond resolution. Initial difficulties with electron bombarded silicon arrays were circumvented by using microchannel plates within the streak tube to provide the needed electronic amplification and digital sensitivity and coupling the 720 element arrays to the electron beam by means of a phosphor on a fiber optics. Two ceramic body tubes with S-20 photocathodes were tested and delivered.

  1. Molecular breeding for developing drought tolerant and disease resistant maize in sub Saharan Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The International Maize and Wheat Improvement Center (CIMMYT), in collaboration with public and private partners, is working on developing and disseminating drought tolerant maize for sub Saharan Africa (SSA) using pedigree selection and molecular breeding. In this paper, we provide an overview of ...

  2. Streaking into middle school science: The Dell Streak pilot project

    NASA Astrophysics Data System (ADS)

    Austin, Susan Eudy

    A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the Streak could be used as an effective instructional tool, and if it could be considered an effective instructional resource for reviewing and preparing for the science assessments. A mixed method research design was used for the study to analyze both quantitative and qualitative results to determine if the Dell Streaks' utilization could achieve the following: 1. instructional strategies would change, 2. it would be an effective instructional tool, and 3. a comparison of the students' test scores and benchmark assessments' scores would provide statistically significant difference. Through the use of an ANOVA it was determined a statistically significant difference had occurred. A Post Hoc analysis was conducted to identify where the difference occurred. Finally a T-test determined was there was no statistically significance difference between the mean End-of-Grade tests and four quarterly benchmark scores of the control and the experimental groups. Qualitative research methods were used to gather results to determine if the Streaks were an effective instructional tool. Classroom observations identified that the teacher's teaching styles and new instructional strategies were implemented throughout the pilot project. Students had an opportunity to complete a questionnaire three times during the pilot project. Results revealed what the students liked about using the devices and the challenges they were facing. The teacher completed a reflective questionnaire throughout the pilot project and offered valuable reflections about the use of the devices in an educational setting. The reflection data supporting the case study was drawn

  3. Slope Streaks in Terra Sabaea

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1 Click on image for larger version

    This HiRISE image shows the rim of a crater in the region of Terra Sabaea in the northern hemisphere of Mars.

    The subimage (figure 1) is a close-up view of the crater rim revealing dark and light-toned slope streaks. Slope streak formation is among the few known processes currently active on Mars. While their mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material.

    Other ideas include the triggering of slope streak formation by possible concentrations of near-surface ice or scouring of the surface by running water from aquifers intercepting slope faces, spring discharge (perhaps brines), and/or hydrothermal activity.

    Several of the slope streaks in the subimage, particularly the three longest darker streaks, show evidence that downslope movement is being diverted around obstacles such as large boulders. Several streaks also appear to originate at boulders or clumps of rocky material.

    In general, the slope streaks do not have large deposits of displaced material at their downslope ends and do not run out onto the crater floor suggesting that they have little reserve kinetic energy. The darkest slope streaks are youngest and can be seen to cross cut and superpose older and lighter-toned streaks. The lighter-toned streaks are believed to be dark streaks that have lightened with time as new dust is deposited on their surface.

    Observation Geometry Image PSP_001808_1875 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Dec-2006. The complete image is centered at 7.4 degrees latitude, 47.0 degrees East longitude. The range to the target site was 272.1 km

  4. Molecular Genetic Analysis and Evolution of Segment 7 in Rice Black-Streaked Dwarf Virus in China

    PubMed Central

    Chen, Yanping; Wu, Jirong; Meng, Qingchang; Han, Xiaohua; Hao, Zhuanfang; Li, Mingshun; Yong, Hongjun; Zhang, Degui; Zhang, Shihuang; Li, Xinhai

    2015-01-01

    Rice black-streaked dwarf virus (RBSDV) causes maize rough dwarf disease or rice black-streaked dwarf disease and can lead to severe yield losses in maize and rice. To analyse RBSDV evolution, codon usage bias and genetic structure were investigated in 111 maize and rice RBSDV isolates from eight geographic locations in 2013 and 2014. The linear dsRNA S7 is A+U rich, with overall codon usage biased toward codons ending with A (A3s, S7-1: 32.64%, S7-2: 29.95%) or U (U3s, S7-1: 44.18%, S7-2: 46.06%). Effective number of codons (Nc) values of 45.63 in S7-1 (the first open reading frame of S7) and 39.96 in S7-2 (the second open reading frame of S7) indicate low degrees of RBSDV-S7 codon usage bias, likely driven by mutational bias regardless of year, host, or geographical origin. Twelve optimal codons were detected in S7. The nucleotide diversity (π) of S7 sequences in 2013 isolates (0.0307) was significantly higher than in 2014 isolates (0.0244, P = 0.0226). The nucleotide diversity (π) of S7 sequences in isolates from Jinan (0.0391) was higher than that from the other seven locations (P < 0.01). Only one S7 recombinant was detected in Baoding. RBSDV isolates could be phylogenetically classified into two groups according to S7 sequences, and further classified into two subgroups. S7-1 and S7-2 were under negative and purifying selection, with respective Ka/Ks ratios of 0.0179 and 0.0537. These RBSDV populations were expanding (P < 0.01) as indicated by negative values for Tajima's D, Fu and Li's D, and Fu and Li's F. Genetic differentiation was detected in six RBSDV subpopulations (P < 0.05). Absolute Fst (0.0790) and Nm (65.12) between 2013 and 2014, absolute Fst (0.1720) and Nm (38.49) between maize and rice, and absolute Fst values of 0.0085-0.3069 and Nm values of 0.56-29.61 among these eight geographic locations revealed frequent gene flow between subpopulations. Gene flow between 2013 and 2014 was the most frequent. PMID:26121638

  5. Priming maize resistance by its neighbors: activating 1,4-benzoxazine-3-ones synthesis and defense gene expression to alleviate leaf disease

    PubMed Central

    Ding, Xupo; Yang, Min; Huang, Huichuan; Chuan, Youcong; He, Xiahong; Li, Chengyun; Zhu, Youyong; Zhu, Shusheng

    2015-01-01

    Plant disease can be effectively suppressed in intercropping systems. Our previous study demonstrated that neighboring maize plants can restrict the spread of soil-borne pathogens of pepper plants by secreting defense compounds into the soil. However, whether maize plant can receive benefits from its neighboring pepper plants in an intercropping system is little attention. We examined the effects of maize roots treated with elicitors from the pepper pathogen Phytophthora capsici and pepper root exudates on the synthesis of 1,4-benzoxazine-3-ones (BXs), the expression of defense-related genes in maize, and their ability to alleviate the severity of southern corn leaf blight (SCLB) caused by Bipolaris maydis. We found that SCLB was significantly reduced after the above treatments. The contents of 1,4-benzoxazine-3-ones (BXs: DIBOA, DIMBOA, and MBOA) and the expression levels of BX synthesis and defense genes in maize roots and shoots were up-regulated. DIMBOA and MBOA effectively inhibited the mycelium growth of Bipolaris maydis at physiological concentrations in maize shoots. Further studies suggested that the defense related pathways or genes in maize roots and shoots were activated by elicitors from the P. capsici or pepper root exudates. In conclusion, maize increased the levels of BXs and defense gene expression both in roots and shoots after being triggered by root exudates and pathogen from neighboring pepper plants, eventually enhancing its resistance. PMID:26528303

  6. Root Interactions in a Maize/Soybean Intercropping System Control Soybean Soil-Borne Disease, Red Crown Rot

    PubMed Central

    Gao, Xiang; Wu, Man; Xu, Ruineng; Wang, Xiurong; Pan, Ruqian; Kim, Hye-Ji; Liao, Hong

    2014-01-01

    Background Within-field multiple crop species intercropping is well documented and used for disease control, but the underlying mechanisms are still unclear. As roots are the primary organ for perceiving signals in the soil from neighboring plants, root behavior may play an important role in soil-borne disease control. Principal Findings In two years of field experiments, maize/soybean intercropping suppressed the occurrence of soybean red crown rot, a severe soil-borne disease caused by Cylindrocladium parasiticum (C. parasiticum). The suppressive effects decreased with increasing distance between intercropped plants under both low P and high P supply, suggesting that root interactions play a significant role independent of nutrient status. Further detailed quantitative studies revealed that the diversity and intensity of root interactions altered the expression of important soybean PR genes, as well as, the activity of corresponding enzymes in both P treatments. Furthermore, 5 phenolic acids were detected in root exudates of maize/soybean intercropped plants. Among these phenolic acids, cinnamic acid was released in significantly greater concentrations when intercropped maize with soybean compared to either crop grown in monoculture, and this spike in cinnamic acid was found dramatically constrain C. parasiticum growth in vitro. Conclusions To the best of our knowledge, this study is the first report to demonstrate that intercropping with maize can promote resistance in soybean to red crown rot in a root-dependent manner. This supports the point that intercropping may be an efficient ecological strategy to control soil-borne plant disease and should be incorporated in sustainable agricultural management practices. PMID:24810161

  7. Dark streaks on talus slopes, Mars

    NASA Astrophysics Data System (ADS)

    Ferguson, H. M.; Lucchitta, B. K.

    1984-04-01

    High-resolution pictures of talus slopes on Mars show small, dark streaks that characteristically widen downward. These streaks are different from the thin and even streaks of various albedos that stream from cliffs on talus slopes, but gradations between the two streak types occur and not all streaks can be classified with confidence. In order to study the nature and origin of the small, widening, dark streaks, all Viking pictures with a resolution of less than 100 m/pixel were surveyed. To date several hundred streaks were located, but only few are of high enough resolution to be confidently identified as widening downwards. The approximate dimensions of the streaks were measured and their shapes, numbers, position, and spacing on slopes were noted. They were plotted on a topographic map, and their relation to topography, geologic units, and regions of distinct thermal inertia and albedo were studied. Also noted was the season at which images containing streaks were acquired and the direction of illumination. Albedo measurements are in progress. Several streaks can be seen stereoscopically, but none are observed on color images. The observation of small dark streaks on talus slopes on Mars is compatible with an interpretation of their origin as eruptions of small masses of wet debris in places where steep walls intersect aquifers or where seasonal equatorial warming permits the local melting of ground ice.

  8. Unraveling Genomic Complexity at a Quantitative Disease Resistance Locus in Maize

    PubMed Central

    Jamann, Tiffany M.; Poland, Jesse A.; Kolkman, Judith M.; Smith, Laurie G.; Nelson, Rebecca J.

    2014-01-01

    Multiple disease resistance has important implications for plant fitness, given the selection pressure that many pathogens exert directly on natural plant populations and indirectly via crop improvement programs. Evidence of a locus conditioning resistance to multiple pathogens was found in bin 1.06 of the maize genome with the allele from inbred line “Tx303” conditioning quantitative resistance to northern leaf blight (NLB) and qualitative resistance to Stewart’s wilt. To dissect the genetic basis of resistance in this region and to refine candidate gene hypotheses, we mapped resistance to the two diseases. Both resistance phenotypes were localized to overlapping regions, with the Stewart’s wilt interval refined to a 95.9-kb segment containing three genes and the NLB interval to a 3.60-Mb segment containing 117 genes. Regions of the introgression showed little to no recombination, suggesting structural differences between the inbred lines Tx303 and “B73,” the parents of the fine-mapping population. We examined copy number variation across the region using next-generation sequencing data, and found large variation in read depth in Tx303 across the region relative to the reference genome of B73. In the fine-mapping region, association mapping for NLB implicated candidate genes, including a putative zinc finger and pan1. We tested mutant alleles and found that pan1 is a susceptibility gene for NLB and Stewart’s wilt. Our data strongly suggest that structural variation plays an important role in resistance conditioned by this region, and pan1, a gene conditioning susceptibility for NLB, may underlie the QTL. PMID:25009146

  9. Wind vs. Dust Devil Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    22 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presents a fine illustration of the difference between streaks made by dust devils and streaks made by wind gusts. Dust devils are usually solitary, spinning vortices. They resemble a tornado, or the swirling motion of a familiar, Tasmanian cartoon character. Wind gusts, on the other hand, can cover a larger area and affect more terrain at the same time. The dark, straight, and parallel features resembling scrape marks near the right/center of this image are thought to have been formed by a singular gust of wind, whereas the more haphazard dark streaks that crisscross the scene were formed by dozens of individual dust devils, acting at different times. This southern summer image is located in Noachis Terra near 67.0oS, 316.2oW. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.

  10. Production of α-L-iduronidase in maize for the potential treatment of a human lysosomal storage disease.

    PubMed

    He, Xu; Haselhorst, Thomas; von Itzstein, Mark; Kolarich, Daniel; Packer, Nicolle H; Gloster, Tracey M; Vocadlo, David J; Clarke, Lorne A; Qian, Yi; Kermode, Allison R

    2012-01-01

    Lysosomal storage diseases are a class of over 70 rare genetic diseases that are amenable to enzyme replacement therapy. Towards developing a plant-based enzyme replacement therapeutic for the lysosomal storage disease mucopolysaccharidosis I, here we expressed α-L-iduronidase in the endosperm of maize seeds by a previously uncharacterized mRNA-targeting-based mechanism. Immunolocalization, cellular fractionation and in situ RT-PCR demonstrate that the α-L-iduronidase protein and mRNA are targeted to endoplasmic reticulum (ER)-derived protein bodies and to protein body-ER regions, respectively, using regulatory (5'- and 3'-UTR) and signal-peptide coding sequences from the γ-zein gene. The maize α-L-iduronidase exhibits high activity, contains high-mannose N-glycans and is amenable to in vitro phosphorylation. This mRNA-based strategy is of widespread importance as plant N-glycan maturation is controlled and the therapeutic protein is generated in a native form. For our target enzyme, the N-glycan structures are appropriate for downstream processing, a prerequisite for its potential as a therapeutic protein. PMID:22990858

  11. Complete Genomic Sequence of Maize Rough Dwarf Virus, a Fijivirus Transmitted by the Small Brown Planthopper.

    PubMed

    Lv, Mingfang; Xie, Li; Yang, Jian; Chen, Jianping; Zhang, Heng-Mu

    2016-01-01

    The nucleotide sequences of the 10 genomic segments of an Italian isolate of maize rough dwarf virus (MRDV) were determined. This first complete genomic sequence of MRDV will help understand the phylogenetic relationships among group 2 fijiviruses and especially the closely related rice black-streaked dwarf virus, which is also found to naturally infect maize. PMID:26847903

  12. Disease Lesion Mimics of Maize as a Potential Source of Resistance to Fusarium Ear Rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium ear rot of maize is a major problem worldwide, often resulting in poor quality grain and contamination with a family of mycotoxins called fumonisins. Fumonisins are produced by Fusarium verticillioides and related species and are acutely toxic to certain livestock. They function by inhibi...

  13. Earth and planetary aeolian streaks: A review

    NASA Astrophysics Data System (ADS)

    Cohen-Zada, Aviv Lee; Blumberg, Dan Gabriel; Maman, Shimrit

    2016-03-01

    Wind streaks are abundant aeolian features that have been observed on planetary surfaces by remote sensing means. They have been widely studied, particularly on Mars and Venus and to a much lesser extent on Earth. In imagery, these streaks appear as elongated features that are easily distinguishable from their surroundings. Geomorphologically, these streaks have, thus far, been interpreted as the presence or absence of small loose particles on the surface, deposited or eroded, respectively, by wind. However, the use of different (optical and radar) remote-sensing tools to study wind streaks has led to uncertain interpretations of these features and has hindered their geomorphological definition. Since wind streaks indicate the prevailing wind direction at the time of their formation, they may be used to map near-surface winds and to estimate atmospheric circulation patterns. The aim of this article is to review the main studies focusing on wind streaks and to present the most up-to-date knowledge on this topic. Moreover, a new perspective for wind streak research is suggested: As 'wind streak' is a collective term for a variety of aeolian features that when viewed from above appear as distinctive albedo surface patterns, we suggest that the term should not be used to refer to a geomorphological feature. Since the definition of wind streaks is constrained to remote sensing rather than to geomorphology and is affected by the inherent biases of remote sensing methods, we suggest that 'wind streaks' should be used as a collective term for aeolian surfaces that are discernable from above as bright and dark patterns due to alterations in the characteristics of the surface or to the presence of bedforms. To better understand the mechanisms, time-frames, climate compatibility of wind streaks and the influences of remote sensing on their appearance, we have compiled a new database containing more than 2,900 Earth wind streaks. A comprehensive study of these Earth wind

  14. Wind Streaks on Earth; Exploration and Interpretation

    NASA Astrophysics Data System (ADS)

    Cohen-Zada, Aviv Lee; Blumberg, Dan G.; Maman, Shimrit

    2015-04-01

    Wind streaks, one of the most common aeolian features on planetary surfaces, are observable on the surface of the planets Earth, Mars and Venus. Due to their reflectance properties, wind streaks are distinguishable from their surroundings, and they have thus been widely studied by remote sensing since the early 1970s, particularly on Mars. In imagery, these streaks are interpreted as the presence - or lack thereof - of small loose particles on the surface deposited or eroded by wind. The existence of wind streaks serves as evidence for past or present active aeolian processes. Therefore, wind streaks are thought to represent integrative climate processes. As opposed to the comprehensive and global studies of wind streaks on Mars and Venus, wind streaks on Earth are understudied and poorly investigated, both geomorphologically and by remote sensing. The aim of this study is, thus, to fill the knowledge gap about the wind streaks on Earth by: generating a global map of Earth wind streaks from modern high-resolution remotely sensed imagery; incorporating the streaks in a geographic information system (GIS); and overlaying the GIS layers with boundary layer wind data from general circulation models (GCMs) and data from the ECMWF Reanalysis Interim project. The study defines wind streaks (and thereby distinguishes them from other aeolian features) based not only on their appearance in imagery but more importantly on their surface appearance. This effort is complemented by a focused field investigation to study wind streaks on the ground and from a variety of remotely sensed images (both optical and radar). In this way, we provide a better definition of the physical and geomorphic characteristics of wind streaks and acquire a deeper knowledge of terrestrial wind streaks as a means to better understand global and planetary climate and climate change. In a preliminary study, we detected and mapped over 2,900 wind streaks in the desert regions of Earth distributed in

  15. Orbital objects detection algorithm using faint streaks

    NASA Astrophysics Data System (ADS)

    Tagawa, Makoto; Yanagisawa, Toshifumi; Kurosaki, Hirohisa; Oda, Hiroshi; Hanada, Toshiya

    2016-02-01

    This study proposes an algorithm to detect orbital objects that are small or moving at high apparent velocities from optical images by utilizing their faint streaks. In the conventional object-detection algorithm, a high signal-to-noise-ratio (e.g., 3 or more) is required, whereas in our proposed algorithm, the signals are summed along the streak direction to improve object-detection sensitivity. Lower signal-to-noise ratio objects were detected by applying the algorithm to a time series of images. The algorithm comprises the following steps: (1) image skewing, (2) image compression along the vertical axis, (3) detection and determination of streak position, (4) searching for object candidates using the time-series streak-position data, and (5) selecting the candidate with the best linearity and reliability. Our algorithm's ability to detect streaks with signals weaker than the background noise was confirmed using images from the Australia Remote Observatory.

  16. Wheat streak mosaic virus P1, not HC-Pro, facilitates disease synergism and suppression of post-transcriptional gene silencing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potyvirus HC-Pro is a suppressor of post-transcriptional gene silencing (PTGS). One consequence of PTGS suppression is pathogenicity enhancement, resulting in disease synergism upon mixed infection of a potyvirus and an unrelated virus. Tritimoviruses also encode HC-Pro sharing limited sequence i...

  17. Bright Streaks and Dark Fans

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below.

    The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans.

    Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide.

    Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

  18. Immunofluorescence localization and ultrastructure of Stewart’s wilt disease bacterium Pantoea stewartii in maize leaves and in its flea beetle vector Chaetocnema pulicaria (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pantoea stewartii is the causal agent of Stewart's wilt of sweet corn, the most serious bacterial disease of sweet corn and maize in the North-Central and Eastern USA. P. stewartii is transmitted mainly by the corn flea beetle Chaetocnema pulicaria (Coleoptera: Chrysomelidae) and this bacterium is a...

  19. Unequal Exchange and Meiotic Instability of Disease-Resistance Genes in the Rp1 Region of Maize

    PubMed Central

    Sudupak, M. A.; Bennetzen, J. L.; Hulbert, S. H.

    1993-01-01

    The Rp1 region of maize was originally characterized as a complex locus which conditions resistance to the fungus Puccinia sorghi, the causal organism in the common rust disease. Some alleles of Rp1 are meiotically unstable, but the mechanism of instability is not known. We have studied the role of recombination in meiotic instability in maize lines homozygous for either Rp1-J or Rp1-G. Test cross progenies derived from a line that was homozygous for Rp1-J, but heterozygous at flanking markers, were screened for susceptible individuals. Five susceptible individuals were derived from 9772 progeny. All five had nonparental combinations of flanking markers; three had one combination of recombinant flanking markers while the other two had the opposite pair. In an identical study with Rp1-G, 20 susceptible seedlings were detected out of 5874 test cross progeny. Nineteen of these were associated with flanking marker exchange, 11 and 8 of each recombinant marker combination. Our results indicate that unequal exchange is the primary mechanism of meiotic instability of Rp1-J and Rp1-G. PMID:8417982

  20. Unequal exchange and meiotic instability of disease-resistance genes in the Rp1 region of maize.

    PubMed

    Sudupak, M A; Bennetzen, J L; Hulbert, S H

    1993-01-01

    The Rp1 region of maize was originally characterized as a complex locus which conditions resistance to the fungus Puccinia sorghi, the causal organism in the common rust disease. Some alleles of Rp1 are meiotically unstable, but the mechanism of instability is not known. We have studied the role of recombination in meiotic instability in maize lines homozygous for either Rp1-J or Rp1-G. Test cross progenies derived from a line that was homozygous for Rp1-J, but heterozygous at flanking markers, were screened for susceptible individuals. Five susceptible individuals were derived from 9772 progeny. All five had nonparental combinations of flanking markers; three had one combination of recombinant flanking markers while the other two had the opposite pair. In an identical study with Rp1-G, 20 susceptible seedlings were detected out of 5874 test cross progeny. Nineteen of these were associated with flanking marker exchange, 11 and 8 of each recombinant marker combination. Our results indicate that unequal exchange is the primary mechanism of meiotic instability of Rp1-J and Rp1-G. PMID:8417982

  1. Maize databases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter is a succinct overview of maize data held in the species-specific database MaizeGDB (the Maize Genomics and Genetics Database), and selected multi-species data repositories, such as Gramene/Ensembl Plants, Phytozome, UniProt and the National Center for Biotechnology Information (NCBI), ...

  2. Electro-optic Phase Grating Streak Spectrometer

    SciTech Connect

    Goldin, F. J.

    2012-08-02

    The electro-optic phase grating streak spectrometer (EOPGSS) generates a time-resolved spectra equivalent to that obtained with a conventional spectrometer/streak camera combination, but without using a streak camera (by far the more expensive and problematic component of the conventional system). The EOPGSS is based on a phase, rather than an amplitude grating. Further, this grating is fabricated of electro-optic material such as, for example, KD*P, by either etching grooves into an E-O slab, or by depositing lines of the E-O material onto an optical flat. An electric field normal to the grating alters the material’s index of refraction and thus affects a shift (in angle) of the output spectrum. Ramping the voltage streaks the spectrum correspondingly. The streak and dispersion directions are the same, so a second (static, conventional) grating disperses the spectrum in the orthogonal direction to prevent different wavelengths from “overwriting” each other. Because the streaking is done by the grating, the streaked output spectrum is recorded with a time-integrating device, such as a CCD. System model, typical design, and performance expectations will be presented.

  3. Fumonisin production is necessary for development of the full spectrum of symptoms indicative of Fusarium verticillioides maize-seedling disease and evidence for disruption of sphingolipid metabolism as the proximate cause.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Fusarium verticillioides infects maize and produces fumonisins, inhibitors of ceramide synthase. To determine the role of fumonisins in maize seedling disease, seeds were inoculated with fumonisin producing or non-producing strains of F. verticillioides. Seedlings grown from seeds inocul...

  4. The Rp3 disease resistance gene of maize: mapping and characterization of introgressed alleles.

    PubMed

    Sanz-Alferez, S; Richter, T E; Hulbert, S H; Bennetzen, J L

    1995-07-01

    The Rp3 locus of maize conditions race-specific resistance to a fungal rust pathogen, Puccinia sorghi. Both morphological and DNA markers were employed to characterize alleles of Rp3 and to accurately position Rp3 on the maize genetic map. DNA marker polymorphisms distinctive to each Rp3 allele were identified, allowing the identification of specific Rp3 alleles in cases where rust races that differentiate particular alleles are not available. In a population of 427 progeny, Rp3 and Rg1 were found to be completely linked, while Lg3 was approximately 3 cM proximal on the long arm of chromosome 3. In this same population, 12 RFLP markers were mapped relative to Rp3; the closest markers were UMC102 (about 1cM distal to Rp1) and NPI114 (1-2 cM proximal). These and additional DNA probes were used to characterize the nature and extent of flanking DNA that was carried along when six different Rp3 alleles were backcrossed into a single background. Depending upon the allele investigated, a minimum of 2-10cM of polymorphic DNA flanking the Rp3 locus was retained through the introgression process. In addition, many of the probes that map near Rp3 were found to detect an additional fragment in the Rp3 region, indicating that portions of this chromosomal segment have been tendemly duplicated. The materials and results generated will permit marker-assisted entry of Rp3 into different maize backgrounds and lay the foundation for the eventual map-based cloning of Rp3. PMID:24169663

  5. Four descriptions: 'Mollicutes'; 'Corn stunt Spiroplasma'; 'Maize bushy stunt phytoplasma'; and, 'Maize redness'

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work includes four chapters, one describing mollicute pathogens of plants in general, and three describing specific mollicute pathogens of maize. Chapters describe the distribution, diseases, symptoms, vector epidemiology and detection of corn stunt spiroplasma, maize bushy stunt phytoplasma a...

  6. Compact Optical Technique for Streak Camera Calibration

    SciTech Connect

    Curt Allen; Terence Davies; Frans Janson; Ronald Justin; Bruce Marshall; Oliver Sweningsen; Perry Bell; Roger Griffith; Karla Hagans; Richard Lerche

    2004-04-01

    The National Ignition Facility is under construction at the Lawrence Livermore National Laboratory for the U.S. Department of Energy Stockpile Stewardship Program. Optical streak cameras are an integral part of the experimental diagnostics instrumentation. To accurately reduce data from the streak cameras a temporal calibration is required. This article describes a technique for generating trains of precisely timed short-duration optical pulses that are suitable for temporal calibrations.

  7. Performance comparison of streak camera recording systems

    SciTech Connect

    Derzon, M.; Barber, T.

    1995-07-01

    Streak camera based diagnostics are vital to the inertial confinement fusion program at Sandia National Laboratories. Performance characteristics of various readout systems coupled to an EGG-AVO streak camera were analyzed and compared to scaling estimates. The purpose of the work was to determine the limits of the streak camera performance and the optimal fielding conditions for the Amador Valley Operations (AVO) streak camera systems. The authors measured streak camera limitations in spatial resolution and sensitivity. Streak camera limits on spatial resolution are greater than 18 lp/mm at 4% contrast. However, it will be difficult to make use of any resolution greater than this because of high spatial frequency variation in the photocathode sensitivity. They have measured a signal to noise of 3,000 with 0.3 mW/cm{sup 2} of 830 nm light at a 10 ns/mm sweep speed. They have compared lens coupling systems with and without micro-channel plate intensifiers and systems using film or charge coupled device (CCD) readout. There were no conditions where film was found to be an improvement over the CCD readout. Systems utilizing a CCD readout without an intensifier have comparable resolution, for these source sizes and at a nominal cost in signal to noise of 3, over those with an intensifier. Estimates of the signal-to-noise for different light coupling methods show how performance can be improved.

  8. ZmPep1, an ortholog of Arabidopsis elicitor peptide 1, regulates maize innate immunity and enhances disease resistance.

    PubMed

    Huffaker, Alisa; Dafoe, Nicole J; Schmelz, Eric A

    2011-03-01

    ZmPep1 is a bioactive peptide encoded by a previously uncharacterized maize (Zea mays) gene, ZmPROPEP1. ZmPROPEP1 was identified by sequence similarity as an ortholog of the Arabidopsis (Arabidopsis thaliana) AtPROPEP1 gene, which encodes the precursor protein of elicitor peptide 1 (AtPep1). Together with its receptors, AtPEPR1 and AtPEPR2, AtPep1 functions to activate and amplify innate immune responses in Arabidopsis and enhances resistance to both Pythium irregulare and Pseudomonas syringae. Candidate orthologs to the AtPROPEP1 gene have been identified from a variety of crop species; however, prior to this study, activities of the respective peptides encoded by these orthologs were unknown. Expression of the ZmPROPEP1 gene is induced by fungal infection and treatment with jasmonic acid or ZmPep1. ZmPep1 activates de novo synthesis of the hormones jasmonic acid and ethylene and induces the expression of genes encoding the defense proteins endochitinase A, PR-4, PRms, and SerPIN. ZmPep1 also stimulates the expression of Benzoxazineless1, a gene required for the biosynthesis of benzoxazinoid defenses, and the accumulation of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside in leaves. To ascertain whether ZmPep1-induced defenses affect resistance, maize plants were pretreated with the peptide prior to infection with fungal pathogens. Based on cell death and lesion severity, ZmPep1 pretreatment was found to enhance resistance to both southern leaf blight and anthracnose stalk rot caused by Cochliobolis heterostrophus and Colletotrichum graminicola, respectively. We present evidence that peptides belonging to the Pep family have a conserved function across plant species as endogenous regulators of innate immunity and may have potential for enhancing disease resistance in crops. PMID:21205619

  9. The maize disease resistance gene Htn1 against northern corn leaf blight encodes a wall-associated receptor-like kinase

    PubMed Central

    Hurni, Severine; Scheuermann, Daniela; Krattinger, Simon G.; Kessel, Bettina; Wicker, Thomas; Herren, Gerhard; Fitze, Mirjam N.; Breen, James; Presterl, Thomas; Ouzunova, Milena; Keller, Beat

    2015-01-01

    Northern corn leaf blight (NCLB) caused by the hemibiotrophic fungus Exserohilum turcicum is an important foliar disease of maize that is mainly controlled by growing resistant maize cultivars. The Htn1 locus confers quantitative and partial NCLB resistance by delaying the onset of lesion formation. Htn1 represents an important source of genetic resistance that was originally introduced from a Mexican landrace into modern maize breeding lines in the 1970s. Using a high-resolution map-based cloning approach, we delimited Htn1 to a 131.7-kb physical interval on chromosome 8 that contained three candidate genes encoding two wall-associated receptor-like kinases (ZmWAK-RLK1 and ZmWAK-RLK2) and one wall-associated receptor-like protein (ZmWAK-RLP1). TILLING (targeting induced local lesions in genomes) mutants in ZmWAK-RLK1 were more susceptible to NCLB than wild-type plants, both in greenhouse experiments and in the field. ZmWAK-RLK1 contains a nonarginine-aspartate (non-RD) kinase domain, typically found in plant innate immune receptors. Sequence comparison showed that the extracellular domain of ZmWAK-RLK1 is highly diverse between different maize genotypes. Furthermore, an alternative splice variant resulting in a truncated protein was present at higher frequency in the susceptible parents of the mapping populations compared with in the resistant parents. Hence, the quantitative Htn1 disease resistance in maize is encoded by an unusual innate immune receptor with an extracellular wall-associated kinase domain. These results further highlight the importance of this protein family in resistance to adapted pathogens. PMID:26124097

  10. Analyses of Twelve New Whole Genome Sequences of Cassava Brown Streak Viruses and Ugandan Cassava Brown Streak Viruses from East Africa: Diversity, Supercomputing and Evidence for Further Speciation.

    PubMed

    Ndunguru, Joseph; Sseruwagi, Peter; Tairo, Fred; Stomeo, Francesca; Maina, Solomon; Djikeng, Appolinaire; Djinkeng, Appolinaire; Kehoe, Monica; Boykin, Laura M

    2015-01-01

    Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are frequently found infecting cassava, one of sub-Saharan Africa's most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families without their primary food source, for an entire year. Twelve new whole genomes, including seven of CBSV and five of UCBSV were uncovered in this research, doubling the genomic sequences available in the public domain for these viruses. These new sequences disprove the assumption that the viruses are limited by agro-ecological zones, show that current diagnostic primers are insufficient to provide confident diagnosis of these viruses and give rise to the possibility that there may be as many as four distinct species of virus. Utilizing NGS sequencing technologies and proper phylogenetic practices will rapidly increase the solution to sustainable cassava production. PMID:26439260

  11. Analyses of Twelve New Whole Genome Sequences of Cassava Brown Streak Viruses and Ugandan Cassava Brown Streak Viruses from East Africa: Diversity, Supercomputing and Evidence for Further Speciation

    PubMed Central

    Ndunguru, Joseph; Sseruwagi, Peter; Tairo, Fred; Stomeo, Francesca; Maina, Solomon; Djinkeng, Appolinaire; Kehoe, Monica; Boykin, Laura M.

    2015-01-01

    Cassava brown streak disease is caused by two devastating viruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are frequently found infecting cassava, one of sub-Saharan Africa’s most important staple food crops. Each year these viruses cause losses of up to $100 million USD and can leave entire families without their primary food source, for an entire year. Twelve new whole genomes, including seven of CBSV and five of UCBSV were uncovered in this research, doubling the genomic sequences available in the public domain for these viruses. These new sequences disprove the assumption that the viruses are limited by agro-ecological zones, show that current diagnostic primers are insufficient to provide confident diagnosis of these viruses and give rise to the possibility that there may be as many as four distinct species of virus. Utilizing NGS sequencing technologies and proper phylogenetic practices will rapidly increase the solution to sustainable cassava production. PMID:26439260

  12. Enhanced Virus Resistance in Transgenic Maize Expressing a dsRNA-Specific Endoribonuclease Gene from E. coli

    PubMed Central

    Liu, He; Tian, Lanzhi; Zhang, Aihong; Zhang, Yanjing; Shi, Lindan; Guo, Bihong; Xu, Jin; Duan, Xifei; Wang, Xianbing; Han, Chenggui; Miao, Hongqin; Yu, Jialin; Li, Dawei

    2013-01-01

    Maize rough dwarf disease (MRDD), caused by several Fijiviruses in the family Reoviridae, is a global disease that is responsible for substantial yield losses in maize. Although some maize germplasm have low levels of polygenic resistance to MRDD, highly resistant cultivated varieties are not available for agronomic field production in China. In this work, we have generated transgenic maize lines that constitutively express rnc70, a mutant E. coli dsRNA-specific endoribonuclease gene. Transgenic lines were propagated and screened under field conditions for 12 generations. During three years of evaluations, two transgenic lines and their progeny were challenged with Rice black-streaked dwarf virus (RBSDV), the causal agent of MRDD in China, and these plants exhibited reduced levels of disease severity. In two normal years of MRDD abundance, both lines were more resistant than non-transgenic plants. Even in the most serious MRDD year, six out of seven progeny from one line were resistant, whereas non-transgenic plants were highly susceptible. Molecular approaches in the T12 generation revealed that the rnc70 transgene was integrated and expressed stably in transgenic lines. Under artificial conditions permitting heavy virus inoculation, the T12 progeny of two highly resistant lines had a reduced incidence of MRDD and accumulation of RBSDV in infected plants. In addition, we confirmed that the RNC70 protein could bind directly to RBSDV dsRNA in vitro. Overall, our data show that RNC70-mediated resistance in transgenic maize can provide efficient protection against dsRNA virus infection. PMID:23593318

  13. Update on the Rochester Optical Streak System

    NASA Astrophysics Data System (ADS)

    Jaanimagi, P. A.

    2005-10-01

    The Rochester Optical Streak System (ROSS) is a modern, self-calibrating, remotely controlled streak camera platform capable of accepting a variety of different streak tubes. The optical calibration module (OCM) for the ROSS camera has been completed and integrated with the main streak tube housing. The OCM incorporates an achromatic Offner triplet that allows fiber-delivered input and free-space propagated signals to be simultaneously relayed to the photocathode. It also encloses of the light sources and reticles required to accomplish a full suite of system calibrations including: autofocus of the input and electron optics, geometric distortion and flat-field correction, time base, system gain, and linearity. We will present data illustrating the system capabilities and our latest results comparing the dynamic performance of the P510 and P820 streak tubes. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

  14. Purification and some properties of reovirus-like particles from leafhoppers and their possible involvement in wallaby ear disease of maize.

    PubMed

    Boccardo, G; Hatta, T; Francki, R I; Grivell, C J

    1980-01-30

    Reovirus-like particles, occurring in association with viroplasms, crystalline arrays and tubules, in the cytoplasm of Cicadulina bimaculata capable of inducing wallaby ear disease in maize, were purified from the insects by differential centrifugation, treatment with the nonionic detergent, Nonidet P-40, and sucrose density gradient centrifugation. The purified particles have a double-shelled icosahedral structure about 70 nm in diameter with external projections (A spikes) about 10 nm long located at the 12 vertices. These intact particles (IPs) are morphologically similar to those of Fiji disease virus (FDV), but are more stable. Cores were produced by enzymatic digestion of IPs with alpha-chymotrypsin. The cores are icosahedra about 57 nm in diameter with projections (B spikes) located at the 12 vertices, resembling those of FDV and cytoplasmic polyhedrosis virus. Immunization of a rabbit with purified IPs resulted in the production of antibodies specific to IPs, cores, and dsRNA. Immunoelectron microscopic investigations revealed that there is no relationship between this virus and FDV, maize rough dwarf, oat sterile dwarf, pangola stunt, and rice ragged stunt viruses, all members of the genus Fijivirus in the family Reoviridae. The nucleic acid extracted from partially purified virus was resolved into 10 segments by polyacrylamide gel electrophoresis. Reovirus-like particles or viroplasms could not be detected in thin sections of maize seedlings colonized by C. bimaculata showing wallaby ear symptoms. In the light of these data the possible etiology of wallaby ear disease is discussed. PMID:18631635

  15. Hot streak characterization in serpentine exhaust nozzles

    NASA Astrophysics Data System (ADS)

    Crowe, Darrell S.

    Modern aircraft of the United States Air Force face increasingly demanding cost, weight, and survivability requirements. Serpentine exhaust nozzles within an embedded engine allow a weapon system to fulfill mission survivability requirements by providing denial of direct line-of-sight into the high-temperature components of the engine. Recently, aircraft have experienced material degradation and failure along the aft deck due to extreme thermal loading. Failure has occurred in specific regions along the aft deck where concentrations of hot gas have come in contact with the surface causing hot streaks. The prevention of these failures will be aided by the accurate prediction of hot streaks. Additionally, hot streak prediction will improve future designs by identifying areas of the nozzle and aft deck surfaces that require thermal management. To this end, the goal of this research is to observe and characterize the underlying flow physics of hot streak phenomena. The goal is accomplished by applying computational fluid dynamics to determine how hot streak phenomena is affected by changes in nozzle geometry. The present research first validates the computational methods using serpentine inlet experimental and computational studies. A design methodology is then established for creating six serpentine exhaust nozzles investigated in this research. A grid independent solution is obtained on a nozzle using several figures of merit and the grid-convergence index method. An investigation into the application of a second-order closure turbulence model is accomplished. Simulations are performed for all serpentine nozzles at two flow conditions. The research introduces a set of characterization and performance parameters based on the temperature distribution and flow conditions at the nozzle throat and exit. Examination of the temperature distribution on the upper and lower nozzle surfaces reveals critical information concerning changes in hot streak phenomena due to changes

  16. Characterization of Brown Streak Virus-Resistant Cassava.

    PubMed

    Anjanappa, Ravi B; Mehta, Devang; Maruthi, M N; Kanju, Edward; Gruissem, Wilhelm; Vanderschuren, Hervé

    2016-07-01

    Cassava brown streak disease (CBSD) has become a major constraint to cassava production in East and Central Africa. The identification of new sources of CBSD resistance is essential to deploy CBSD mitigation strategies, as the disease is progressing westwards to new geographical areas. A stringent infection method based on top cleft-grafting combined with precise virus titer quantitation was utilized to screen 14 cassava cultivars and elite breeding lines. When inoculated with mixed infections of Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), the scions of elite breeding lines KBH 2006/18 and KBH 2006/26 remained symptom-free during a 16-week period of virus graft inoculation, while susceptible varieties displayed typical CBSD infection symptoms at 4 weeks after grafting. The identified CBSD resistance was stable under the coinoculation of CBSV and UCBSV with cassava geminiviruses. Double-grafting experiments revealed that transmission of CBSV and UCBSV to CBSD-susceptible top scions was delayed when using intermediate scions of elite breeding lines KBH 2006/18 and KBH 2006/26. Nonetheless, comparison of virus systemic movement using scions from KBH2006/18 and a transgenic CBSD resistant 60444 line (60444-Hp9 line) showed that both CBSV and UCBSV move at undetectable levels through the stems. Further, protoplast-based assays of virus titers showed that the replication of CBSV is inhibited in the resistant line KBH2006/18, suggesting that the identified CBSD resistance is at least partially based on inhibition of virus replication. Our molecular characterization of CBSD resistance in cassava offers a robust virus-host system to further investigate the molecular determinants of CBSD resistance. PMID:27070326

  17. Frost streaks in the south polar cap of Mars

    NASA Technical Reports Server (NTRS)

    Thomas, P.; Veverka, J.; Campos-Marquetti, R.

    1979-01-01

    Viking Orbiter images of the annual south polar cap on Mars exhibit elongated bright features that are associated with craters and resemble wind streaks observed elsewhere on Mars. The study focuses on the well-documented frost streaks. The discussion covers the morphology of frost streaks, occurrence, seasonal behavior, thickness of frost in streak deposits, wind patterns inferred from frost streaks and other eolian features in the south polar region, formation of frost streaks, and other locales of preferential frost accumulation. The form and seasonal behavior of the bright elongated albedo markings which extend from the rims of many craters in the south polar cap suggest that they are accumulations of CO2 frost in the lee of craters. The frost streaks appear in the fall, increasing in length but not changing in direction during fall and winter. The frost streaks indicate a prograde circulation pattern of near-surface winds around the pole. Other details are also presented.

  18. ASTRiDE: Automated Streak Detection for Astronomical Images

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Won

    2016-05-01

    ASTRiDE detects streaks in astronomical images using a "border" of each object (i.e. "boundary-tracing" or "contour-tracing") and their morphological parameters. Fast moving objects such as meteors, satellites, near-Earth objects (NEOs), or even cosmic rays can leave streak-like traces in the images; ASTRiDE can detect not only long streaks but also relatively short or curved streaks.

  19. The first satellite laser echoes recorded on the streak camera

    NASA Technical Reports Server (NTRS)

    Hamal, Karel; Prochazka, Ivan; Kirchner, Georg; Koidl, F.

    1993-01-01

    The application of the streak camera with the circular sweep for the satellite laser ranging is described. The Modular Streak Camera system employing the circular sweep option was integrated into the conventional Satellite Laser System. The experimental satellite tracking and ranging has been performed. The first satellite laser echo streak camera records are presented.

  20. Perception of Randomness: On the Time of Streaks

    ERIC Educational Resources Information Center

    Sun, Yanlong; Wang, Hongbin

    2010-01-01

    People tend to think that streaks in random sequential events are rare and remarkable. When they actually encounter streaks, they tend to consider the underlying process as non-random. The present paper examines the time of pattern occurrences in sequences of Bernoulli trials, and shows that among all patterns of the same length, a streak is the…

  1. Dark Streaks Over-riding Inactive Dunes

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Not all sand dunes on Mars are active in the modern martian environment. This example from the Lycus Sulci (Olympus Mons'aureole') region shows a case where small windblown dunes at the base of a slope have been over-ridden by more recent dark streaks (arrows). The dark streaks are most likely caused by what geologists call mass wasting or mass movement (landslides and avalanches are mass movements). Dark slope streaks such as these are common in dustier regions of Mars, and they appear to result from movement of extremely dry dust or sand in an almost fluidlike manner down a slope. This movement disrupts the bright dust coating on the surface and thus appears darker than the surrounding terrain.

    In this case, the dark slope streaks have moved up and over the dunes at the bottom of the slope, indicating that the process that moves sediment down the slope is more active (that is, it has occurred more recently and hence is more likely to occur) in the modern environment than is the movement of dunes and ripples at this location on Mars. The dunes, in fact, are probably mantled by dust. This October 1997 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture is illuminated from the left and located near 31.6oN, 134.0oW.

  2. Bichromatic particle streak velocimetry bPSV

    NASA Astrophysics Data System (ADS)

    Voss, Björn; Stapf, Julian; Berthe, André; Garbe, Christoph S.

    2012-11-01

    We propose a novel technique for three-dimensional three-component (3D3C) interfacial flow measurement. It is based on the particle streak velocimetry principle. A relatively long integration time of the camera is used for capturing the movement of tracer particles as streaks on the sensor. The velocity along these streaks is extracted by periodically changing the illumination using a known pattern. A dye with different absorption characteristics in two distinct wavelengths is used to color the fluid. The depth of particles relative to the fluid interface can then be computed from their intensities when illuminated with light sources at those two different wavelengths. Hence, from our approach, a bichromatic, periodical illumination together with an image processing routine for precisely extracting particle streak features is used for measuring 3D3C fluid flow with a single camera. The technique is applied to measuring turbulent Rayleigh-Bénard convection at the free air--water interface. Using Lagrangian statistics, we are able to demonstrate a clear transition from the Batchelor regime to the Richardson regime, both of which were postulated for isotropic turbulence. The relative error of the velocity extraction of our new technique was found to be below 0.5 %.

  3. Maize lethal necrosis (MLN), an emerging threat to maize-based food security in sub-Saharan Africa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In sub-Saharan Africa, maize is a staple food and key determinant of food security for smallholder farming communities. Pest and disease outbreaks are key constraints to maize productivity. In September 2011, a serious disease outbreak, later diagnosed as maize lethal necrosis (MLN), was reported on...

  4. Evaluation of banana hybrids for tolerance to black leaf streak (Mycosphaerella fijiensis Morelet) in Puerto Rico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola, respectively, are responsible for significant los...

  5. Chromatin Structure of Wheat Breeding Lines Resistant to Wheat Streak Mosaic Virus.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat Streak Mosaic Virus (WSMV) is an important disease limiting wheat production, however no WSMV resistance effective above 18°C is present within the primary genetic pool of wheat (Triticum aestivum L.). In contrast, the wild relative Thinopyrum intermedium (2n=6x=42) shows good resistance to WS...

  6. Wind Streaks on Venus: Clues to Atmospheric Circulation

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Schubert, Gerald; Limonadi, Daniel; Bender, Kelly C.; Newman, William I.; Thomas, Peggy E.; Weitz, Catherine M.; Wall, Stephen D.

    1994-01-01

    Magellan images reveal surface features on Venus attributed to wind processes. Sand dunes, wind-sculpted hills, and more than 5830 wind streaks have been identified. The streaks serve as local "wind vanes," representing wind direction at the time of streak formation and allowing the first global mapping of near-surface wind patterns on Venus. Wind streaks are oriented both toward the equator and toward the west. When streaks associated with local transient events, such as impact cratering, are deleted, the westward component is mostly lost but the equatorward component remains. This pattern is consistent with a Hadley circulation of the lower atmosphere.

  7. Photonic streaking of attosecond pulse trains

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Taec; Zhang, Chunmei; Ruchon, Thierry; Hergott, Jean-François; Auguste, Thierry; Villeneuve, D. M.; Corkum, P. B.; Quéré, F.

    2013-08-01

    High harmonic radiation, produced when intense laser pulses interact with matter, is composed of a train of attosecond pulses. Individual pulses in this train carry information on ultrafast dynamics that vary from one half-optical-cycle to the next. Here, we demonstrate an all-optical photonic streaking measurement that provides direct experimental access to each attosecond pulse by mapping emission time onto propagation angle. This is achieved by inducing an ultrafast rotation of the instantaneous laser wavefront at the focus. We thus time-resolve attosecond pulse train generation, and hence the dynamics in the nonlinear medium itself. We apply photonic streaking to harmonic generation in gases and directly observe, for the first time, the influence of non-adiabatic electron dynamics and plasma formation on the generated attosecond pulse train. These experimental and numerical results also provide the first evidence of the generation of attosecond lighthouses in gases, which constitute ideal sources for attosecond pump-probe spectroscopy.

  8. First report of bacterial streak of fennel (Foeniculum vulgare) in California caused by Pseudomonas syringae pv. apii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new bacterial streak disease appeared on fennel leaves, stems and bulbs grown in Salinas California production fields. Initial symptoms consisted of small black lesions on stems that spread down the stem to the bulbs and up the stem to leaves as the disease progressed. The disease rendered the pl...

  9. Understanding baseball team standings and streaks

    NASA Astrophysics Data System (ADS)

    Sire, C.; Redner, S.

    2009-02-01

    Can one understand the statistics of wins and losses of baseball teams? Are their consecutive-game winning and losing streaks self-reinforcing or can they be described statistically? We apply the Bradley-Terry model, which incorporates the heterogeneity of team strengths in a minimalist way, to answer these questions. Excellent agreement is found between the predictions of the Bradley-Terry model and the rank dependence of the average number team wins and losses in major-league baseball over the past century when the distribution of team strengths is taken to be uniformly distributed over a finite range. Using this uniform strength distribution, we also find very good agreement between model predictions and the observed distribution of consecutive-game team winning and losing streaks over the last half-century; however, the agreement is less good for the previous half-century. The behavior of the last half-century supports the hypothesis that long streaks are primarily statistical in origin with little self-reinforcing component. The data further show that the past half-century of baseball has been more competitive than the preceding half-century.

  10. Particle Streak Velocimetry of Supersonic Nozzle Flows

    NASA Technical Reports Server (NTRS)

    Willits, J. D.; Pourpoint, T. L.

    2016-01-01

    A novel velocimetry technique to probe the exhaust flow of a laboratory scale combustor is being developed. The technique combines the advantages of standard particle velocimetry techniques and the ultra-fast imaging capabilities of a streak camera to probe high speed flows near continuously with improved spatial and velocity resolution. This "Particle Streak Velocimetry" technique tracks laser illuminated seed particles at up to 236 picosecond temporal resolution allowing time-resolved measurement of one-dimensional flows exceeding 2000 m/s as are found in rocket nozzles and many other applications. Developmental tests with cold nitrogen have been performed to validate and troubleshoot the technique with supersonic flows of much lower velocity and without background noise due to combusting flow. Flow velocities on the order of 500 m/s have been probed with titanium dioxide particles and a continuous-wave laser diode. Single frame images containing multiple streaks are analyzed to find the average slope of all incident particles corresponding to the centerline axial flow velocity. Long term objectives for these tests are correlation of specific impulse to theoretical combustion predictions and direct comparisons between candidate green fuels and the industry standard, monomethylhydrazine, each tested under identical conditions.

  11. ZmPep1, an ortholog of Arabidopsis elicitor Peptide 1, regulates maize innate immunity and enhances disease resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ZmPep1 is a bioactive peptide encoded by a previously uncharacterized maize gene termed ZmPROPEP1. The gene was identified by sequence similarity as an ortholog of the Arabidopsis AtPROPEP1 gene, which encodes the precursor protein of elicitor peptide 1 (AtPep1). Together with its receptors, AtPEPR1...

  12. Reinventing MaizeGDB

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Maize Database (MaizeDB) to the Maize Genetics and Genomics Database (MaizeGDB) turns 20 this year, and such a significant milestone must be celebrated! With the release of the B73 reference sequence and more sequenced genomes on the way, the maize community needs to address various opportunitie...

  13. Mapping QTL Contributing to SCMV Resistance in Tropical Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane mosaic virus (SCMV) has been increasing in importance as a maize disease in Brazil. In this study, were mapped and characterized quantitative trait loci (QTL) associated to resistance to SCMV in a maize population consisting of 150 F2:3 families from the cross between two tropical maize i...

  14. Quantitative trait loci for resistance to Maize rayado fino virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize rayado fino virus (MRFV) causes one of the most important virus diseases of maize in regions of Mexico, Central and South America, where it causes moderate to severe yield losses. The virus is found from the southern United States. to northern Argentina where its vector, the maize leafhopper D...

  15. Maize: Overview

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize is an important cereal crop that is well-suited to industrial agriculture, both in grain production and in grain utilization. Starch, protein and oil are the three major components of the grain. Several processing methods yield many different food ingredients. In addition, whole grain is pr...

  16. Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization

    PubMed Central

    Manching, Heather C.; Balint-Kurti, Peter J.; Stapleton, Ann E.

    2014-01-01

    Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus). Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P < 0.001). Lower species richness—alpha diversity—was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression. PMID:25177328

  17. Signal averaging x-ray streak camera with picosecond jitter

    NASA Astrophysics Data System (ADS)

    Maksimchuk, A.; Kim, M.; Workman, J.; Korn, G.; Squier, J.; Du, D.; Umstadter, D.; Mourou, G.; Bouvier, M.

    1996-03-01

    We have developed an averaging picosecond x-ray streak camera using a dc-biased photoconductive switch as a generator of a high-voltage ramp. The streak camera is operated at a sweep speed of up to 8 ps/mm, shot-to-shot jitter is less than ±1 ps. The streak camera has been used to measure the time history of broadband x-ray emission from an ultrashort pulse laser-produced plasma. Accumulation of the streaked x-ray signals significantly improved the signal-to-noise ratio of the data obtained.

  18. Compressible laminar streaks with wall suction

    NASA Astrophysics Data System (ADS)

    Ricco, Pierre; Shah, Daniel; Hicks, Peter D.

    2013-05-01

    The response of a compressible laminar boundary layer subject to free-stream vortical disturbances and steady mean-flow wall suction is studied. The theoretical frameworks of Leib et al. [J. Fluid Mech. 380, 169-203 (1999), 10.1017/S0022112098003504] and Ricco and Wu [J. Fluid Mech. 587, 97-138 (2007), 10.1017/S0022112007007070], based on the linearized unsteady boundary-region equations, are adopted to study the influence of suction on the kinematic and thermal streaks arising through the interaction between the free-stream vortical perturbations and the boundary layer. In the asymptotic limit of small spanwise wavelength compared with the boundary layer thickness, i.e., when the disturbance flow is conveniently described by the steady compressible boundary region equations, the effect of suction is mild on the velocity fluctuations and negligible on the temperature fluctuations. When the spanwise wavelength is comparable with the boundary layer thickness, small suction values intensify the supersonic streaks, while higher transpiration levels always stabilize the disturbances at all Mach numbers. At larger spanwise wavelengths, very small amplitudes of wall transpiration have a dramatic stabilizing effect on all boundary layer fluctuations, which can take the form of transiently growing thermal streaks, large amplitude streamwise oscillations, or oblique exponentially growing Tollmien-Schlichting waves, depending on the Mach number and the wavelengths. The range of wavenumbers for which the exponential growth occurs becomes narrower and the location of instability is significantly shifted downstream by mild suction, indicating that wall transpiration can be a suitable vehicle for delaying transition when the laminar breakdown is promoted by these unstable disturbances. The typical streamwise wavelength of these disturbances is instead not influenced by suction, and asymptotic triple deck theory predicts the strong changes in growth rate and the very mild

  19. Characterization of the inaA gene and expression of ice nucleation phenotype in Pantoea ananatis isolates from Maize White Spot disease.

    PubMed

    Miller, A M; Figueiredo, J E F; Linde, G A; Colauto, N B; Paccola-Meirelles, L D

    2016-01-01

    Maize White Spot (MWS), a foliar disease caused by Pantoea ananatis, could cause up to 60% yield loss. Some strains of P. ananatis harboring the ice nucleation gene inaA catalyze the formation of ice nuclei, causing tissue damage at temperatures slightly below freezing. Little is known about the relationship between the presence of the ina gene in this maize pathogen and its expression during the phenomenon of ice nucleus formation. Here, we attempted to verify the presence of the inaA gene and the expression of phenotype in vitro. The identity of the isolates and the presence of the inaA gene were determined by P. ananatis species-specific primers. The expression of the inaA gene was assessed in vitro by the visualization of ice-crystal formation in water at subzero temperatures. A total of ninety P. ananatis isolates from MWS lesions were characterized. The presence of the inaA gene was confirmed by gel electrophoresis of the 350-400-bp PCR products. The inaA primers did not lead to DNA fragment amplification in three isolates. The ice nucleation phenotype was expressed in 83.34% of the isolates carrying the inaA gene. Our study showed that the ice nucleation in P. ananatis isolated from MWS lesions was dependent on the presence of a functional ina gene in the genome. We also found evidence indicating that some P. ananatis strains have a mutated form of the inaA gene, producing a non-functional ice nucleation protein. This is the first report on inaA gene characterization in P. ananatis isolates from Maize White Spot. PMID:26985943

  20. Association mapping of quantitative trait loci responsible for resistance to Bacterial Leaf Streak and Spot Blotch in spring wheat landraces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, and spot blotch (SB), caused by Cochliobolus sativus are two major diseases of wheat (Triticum aestivum L.). Planting resistant cultivars is the best approach to manage these diseases and identifying new sources of resistan...

  1. X-ray streak crystal spectography

    SciTech Connect

    Kauffman, R.L.; Brown, T.; Medecki, H.

    1983-07-01

    We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11/sup 0/ to 38/sup 0/ and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/..delta..E > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given.

  2. Pantoea stewartii subsp. stewartii exhibits surface motility, which is a critical aspect of Stewart's wilt disease development on maize.

    PubMed

    Herrera, Carmen M; Koutsoudis, Maria D; Wang, Xiaolei; von Bodman, Susanne B

    2008-10-01

    Pantoea stewartii subsp. stewartii is a plant-pathogenic bacterium that causes Stewart's vascular wilt in maize. The organism is taxonomically described as aflagellated and nonmotile. We recently showed that P. stewartii colonizes the xylem of maize as sessile, cell-wall-adherent biofilms. Biofilm formation is a developmental process that generally involves some form of surface motility. For that reason, we reexamined the motility properties of P. stewartii DC283 based on the assumption that the organism requires some form of surface motility for biofilm development. Here, we show that the organism is highly motile on agar surfaces. This motility is flagella dependent, shown by the fact that a fliC mutant, impaired in flagellin subunit synthesis, is nonmotile. Motility also requires the production of stewartan exopolysaccharide. Moreover, surface motility plays a significant role in the colonization of the plant host. PMID:18785831

  3. Whole-genome expression analysis of Rice black-streaked dwarf virus in different plant hosts and small brown planthopper.

    PubMed

    Xu, Qiufang; Ni, Haiping; Zhang, Jinfeng; Lan, Ying; Ren, Chunmei; Zhou, Yijun

    2015-11-10

    Rice black-streaked dwarf virus (RBSDV) can infect a number of gramineous plants and cause severe crop yield losses in southeast Asian countries. The virus is transmitted by small brown planthopper (SBPH) in a persistent circulative manner. The interactions between RBSDV and its different hosts remain unknown. Besides, how the virus adjusts itself to infect different hosts is unclear. In the present study, the relative RNA levels of the thirteen RBSDV genes in rice, maize, wheat, and SBPH were measured by real-time quantitative PCR. P7-1 and P10 genes were predominantly expressed whereas P8 and P7-2 genes were expressed at low levels in plant hosts. Similar to the expression in rice, P7-1 was the most abundantly expressed gene and P8 was expressed at the lowest level in SBPH, indicating that RBSDV adopts the same strategy to infect distinct hosts. The high expression levels of the P7-1 gene in both plants and insect suggest that it can be used as the target gene for disease diagnostics. However, the expression levels of some genes varied from host to host. P5-1, P6 and P9-1, the components of the RBSDV viroplasm, are differentially expressed in different hosts. Moreover, western blot analysis showed that the quantity of the P9-1 protein was more abundant in SBPH than in plant hosts. These data indicate that the virus may adjust its own gene expression to replicate in different hosts. Analysis of time course of gene expression revealed that P7-1 stands out as the only gene highly expressed at the earliest time point and its expression precedes all others throughout infection from 8 to 24days post-inoculation. The high expression levels of the P7-1 gene suggest that it plays a significant role in RBSDV-host interactions. PMID:26149652

  4. Mass movement slope streaks imaged by the Mars Orbiter Camera

    NASA Astrophysics Data System (ADS)

    Sullivan, Robert; Thomas, Peter; Veverka, Joseph; Malin, Michael; Edgett, Kenneth S.

    2001-10-01

    Narrow, fan-shaped dark streaks on steep Martian slopes were originally observed in Viking Orbiter images, but a definitive explanation was not possible because of resolution limitations. Pictures acquired by the Mars Orbiter Camera (MOC) aboard the Mars Global Surveyor (MGS) spacecraft show innumerable examples of dark slope streaks distributed widely, but not uniformly, across the brighter equatorial regions, as well as individual details of these features that were not visible in Viking Orbiter data. Dark slope streaks (as well as much rarer bright slope streaks) represent one of the most widespread and easily recognized styles of mass movement currently affecting the Martian surface. New dark streaks have formed since Viking and even during the MGS mission, confirming earlier suppositions that higher contrast dark streaks are younger, and fade (brighten) with time. The darkest slope streaks represent ~10% contrast with surrounding slope materials. No small outcrops supplying dark material (or bright material, for bright streaks) have been found at streak apexes. Digitate downslope ends indicate slope streak formation involves a ground-hugging flow subject to deflection by minor topographic obstacles. The model we favor explains most dark slope streaks as scars from dust avalanches following oversteepening of air fall deposits. This process is analogous to terrestrial avalanches of oversteepened dry, loose snow which produce shallow avalanche scars with similar morphologies. Low angles of internal friction typically 10-30¡ for terrestrial loess and clay materials suggest that mass movement of (low-cohesion) Martian dusty air fall is possible on a wide range of gradients. Martian gravity, presumed low density of the air fall deposits, and thin (unresolved by MOC) failed layer depths imply extremely low cohesive strength at time of failure, consistent with expectations for an air fall deposit of dust particles. As speed increases during a dust avalanche, a

  5. SDOSS: A spatially discriminating, optical streaked spectrograph

    SciTech Connect

    Cobble, J.; Evans, S.; Fernandez, J.; Oertel, J.; Watt, R.; Wilde, B.

    1995-05-01

    SDOSS is employed to study broadband laser scattering encompassing SBS, SRS, and the 3/2-{omega} signature of two plasmon decay for ns-scale laser-plasma experiments with 351 or 527-nm drive. It uses a Cassegrain telescope to image scattered light from a laser plasma onto a field stop. The telescope magnification and the stop aperture provide spatial discrimination of target plane scatter. A UV lens relays the image to a 0.25-m spectrograph which is lens coupled to a streak camera with an S-1 photocathode. The streak output is imaged onto a CCD camera. In its 512 x 480 pixel array, the CCD covers a spectral range from 200 to 800 nm with 4-nm resolution and can be adjusted to look from 350 to 1,060 nm. The sweep speed is variable with full window values of 30, 12, 6 ns, and faster. An optical fiducial provides a spectral and temporal marker. On the Livermore Nova laser, SDOSS has been used to determine spatial density in gas-filled hohlraums from SRS signals. At Trident in Los Alamos, it has been employed for similar measurements with long scale length plasmas in SBS and SRS seeding experiments. It has proven to be a versatile tool for studying the physics of laser-generated plasmas.

  6. Radar-visible wind streaks in the Altiplano of Bolivia

    NASA Technical Reports Server (NTRS)

    Greeley, R.; Christensen, P.

    1984-01-01

    Isolated knobs that are erosional remnants of central volcanoes or of folded rocks occur in several areas of the Altiplano are visible on both optical and images. The optically visible streaks occur in the immediate lee of the knobs, whereas the radar visible streaks occur in the zone downwind between the knobs. Aerial reconnaissance and field studies showed that the optically visible streaks consist of a series of small ( 100 m wide) barchan and barchanoid dunes, intradune sand sheets, and sand hummocks (large shrub coppice dunes) up to 15 m across and 5 m high. On LANDSAT images these features are poorly resolved but combine to form a bright streak. On the radar image, this area also appears brighter than the zone of the radar dark streak; evidently, the dunes and hummocks serve as radar reflectors. The radar dark streak consists of a relatively flat, smooth sand sheet which lacks organized aerolian bedforms, other than occasional ripples. Wind velocity profiles show a greater U value in the optically bright streak zone than in the radar dark streak.

  7. A possible scenario for the evolution of Banana streak virus in banana.

    PubMed

    Iskra-Caruana, Marie-Line; Chabannes, Matthieu; Duroy, Pierre-Olivier; Muller, Emmanuelle

    2014-06-24

    Outbreaks of Banana streak virus (BSV) have been recorded worldwide where Musa spp. is grown during the last 20 years with no convincing evidence of epidemics. Epidemics were previously reported in Uganda where BSV is currently endemic. BSV is a plant pararetrovirus of the family Caulimoviridae, genus Badnavirus it causes chlorosis leaf streak disease. The information currently available on banana streak disease makes it possible to identify a complex of distinct BSV species each causing the same disease. BSV exists in two states: one as an episomal form, infecting plant cells; the other as viral DNA integrated within the B genome of banana (endogenous BSV-eBSV) forming a viral genome for de novo viral particles. Both forms can be infectious in banana plants. The BSV phylogeny is polyphyletic with BSV distributed in two clades. Clade 1 clusters BSV species that occur worldwide and may have an eBSV counterpart, whereas Clade 3 only comprises BSV species from Uganda. Clearly, two distinct origins explain such BSV diversity. However, the epidemiology/outbreaks of BSV remains unclear and the role of eBSV needs to be clarified. In this review, the biodiversity of BSV is explained and discussed in the light of field and molecular epidemiology data. A scheme is proposed for the co-evolution of BSV and banana based on old or recent infection hypotheses related to African domestication sites and banana dissemination to explain the disease context. PMID:24457073

  8. Structure-Based Computational Study of Two Disease Resistance Gene Homologues (Hm1 and Hm2) in Maize (Zea mays L.) with Implications in Plant-Pathogen Interactions

    PubMed Central

    Maharana, Jitendra; Sahu, Jagajjit; Sen, Priyabrata; Modi, Mahendra Kumar; Choudhury, Manabendra Dutta; Barooah, Madhumita

    2014-01-01

    The NADPH-dependent HC-toxin reductases (HCTR1 and 2) encoded by enzymatic class of disease resistance homologous genes (Hm1 and Hm2) protect maize by detoxifying a cyclic tetrapeptide, HC-toxin, secreted by the fungus Cochliobolus carbonum race 1(CCR1). Unlike the other classes' resistance (R) genes, HCTR-mediated disease resistance is an inimitable mechanism where the avirulence (Avr) component from CCR1 is not involved in toxin degradation. In this study, we attempted to decipher cofactor (NADPH) recognition and mode of HC-toxin binding to HCTRs through molecular docking, molecular dynamics (MD) simulations and binding free energy calculation methods. The rationality and the stability of docked complexes were validated by 30-ns MD simulation. The binding free energy decomposition of enzyme-cofactor complex was calculated to find the driving force behind cofactor recognition. The overall binding free energies of HCTR1-NADPH and HCTR2-NADPH were found to be −616.989 and −16.9749 kJ mol−1 respectively. The binding free energy decomposition revealed that the binding of NADPH to the HCTR1 is mainly governed by van der Waals and nonpolar interactions, whereas electrostatic terms play dominant role in stabilizing the binding mode between HCTR2 and NADPH. Further, docking analysis of HC-toxin with HCTR-NADPH complexes showed a distinct mode of binding and the complexes were stabilized by a strong network of hydrogen bond and hydrophobic interactions. This study is the first in silico attempt to unravel the biophysical and biochemical basis of cofactor recognition in enzymatic class of R genes in cereal crop maize. PMID:24847713

  9. Effect of temperature on wheat streak mosaic virus replication and movement in resistant and susceptible wheat cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat streak mosaic virus (WSMV) is an economically important virus causing annual average yield losses of ~2-3% in winter wheat across the Great Plains. Temperature is one of the most important environmental factors that influences disease development and severity. The objective of this study was t...

  10. A compensating wheat-Thinopyrum intermedium Robertsonian translocation conferring resistance to wheat streak mosaic virus and Triticum mosaic virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat streak mosaic virus (WSMV), is a potentially devastating disease of common wheat in the Great Plains of North America. So far, two genes conferring resistance to WSMV have been named and used in cultivar improvement. Here we report a new source of resistance that was derived from a wheat-Th. i...

  11. Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a costeffective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chrom...

  12. Streak interactions and breakdown in boundary layer flows

    NASA Astrophysics Data System (ADS)

    Brandt, Luca; de Lange, H. C.

    2008-02-01

    The objective of this paper is to show that the interaction of streamwise velocity streaks of finite length can lead to turbulent breakdown in the flat-plate boundary layer flow. The work is motivated by previous numerical and experimental studies of transitional flows where the high-frequency oscillations leading to turbulence are seen to form in the region of strongest shear induced by streaks in relative motion. Therefore, a model for the interaction of steady and unsteady (i.e., slowly moving in the spanwise direction) spanwise periodic streaks is proposed. The interaction of two subsequent streaks is investigated for varying collision parameters. In particular, the relative spanwise position and angle are considered. The results show that the interaction is able to produce both a symmetric and asymmetric breakdown without the need for additional random noise from the main stream. Velocity structures characteristic of both scenarios are analyzed. Hairpin and Λ vortices are found in the case of symmetric collision between a low-speed region and an incoming high-speed streak, when a region of strong wall-normal shear is induced. Alternatively, when the incoming high-momentum fluid is misaligned with the low-speed streak in front, single quasi-streamwise vortices are identified. Despite the different symmetry at the breakdown, the detrimental interaction involves for both cases the tail of a low-speed region and the head of a high-speed streak. Further, the breakdown appears in both scenarios as an instability of three-dimensional shear layers formed between the two streaks. The streak interaction scenario is suggested to be of relevance for turbulence production in wall-bounded flows.

  13. High Performance Imaging Streak Camera for the National Ignition Facility

    SciTech Connect

    Opachich, Y. P.; Kalantar, D.; MacPhee, A.; Holder, J.; Kimbrough, J.; Bell, P. M.; Bradley, D.; Hatch, B.; Brown, C.; Landen, O.; Perfect, B. H.; Guidry, B.; Mead, A.; Charest, M.; Palmer, N.; Homoelle, D.; Browning, D.; Silbernagel, C.; Brienza-Larsen, G.; Griffin, M.; Lee, J. J.; Haugh, M. J.

    2012-01-01

    An x-ray streak camera platform has been characterized and implemented for use at the National Ignition Facility. The camera has been modified to meet the experiment requirements of the National Ignition Campaign and to perform reliably in conditions that produce high EMI. A train of temporal UV timing markers has been added to the diagnostic in order to calibrate the temporal axis of the instrument and the detector efficiency of the streak camera was improved by using a CsI photocathode. The performance of the streak camera has been characterized and is summarized in this paper. The detector efficiency and cathode measurements are also presented.

  14. Temporal Contrast Changes in Dark Slope Streaks on Mars

    NASA Astrophysics Data System (ADS)

    Chilton, H.; Phillips, C. B.; Fenton, L. K.; Brown, A. J.

    2012-12-01

    Dark slope streaks on Mars, first observed in Viking images, provide insight into one of the most active and dynamic processes observed on the planet's surface. While various formation models have been suggested [1][2][3], dust avalanches seem to best explain streak origin and characteristics[4][5]. New dark streaks are observed to have the greatest contrast to their surroundings while older streaks have lower contrast, suggesting that streaks fade over time. One theory for this is atmospheric dust fallout slowly raising the albedo of the surface exposed by the dust avalanche, resulting in increased streak albedo over time until the streak becomes indistinguishable from the surrounding surface. In this study, we attempt an initial evaluation of changes in streak brightness relative to surroundings, with a first order correction for incidence angle[6] based on MOLA data. CRISM images were first identified for spatial and temporal overlap, then further selected for those image sets with well-matched viewing geometries. Locations included Nicholson Crater (CRISM images: frt0000c287_07_de165l, hrl0000d0f1_7_de165l, frt00018c69_07_de165l) and South of Nestus Valles (CRISM images: hrl00004a5e_07_de181l, hrl0000812a_07_de182l) as well as Naktong Vallis (CRISM images: hrl0000898d_07_de182l, hrl00005337_07_de182l) and an area in Lycus Sulci (CRISM images: hrl0000a52a_07_de166l, hrl0000ce5f_07_if175l). We focused on 1 micron wavelength CRISM images in order to reduce atmosphric interference. From here, brightness (observed radiance divided by solar irradiance at Mars divided by pi) values were collected along individual streaks, with measurements at multiple locations along the streak length and alongside at points of similar elevation to streak measurements to establish an average contrast ratio. Both on-streak and off-streak values were divided by the cosine of their respective local MOLA incidence angles to correct for brightness variation due to solar flux and

  15. Active Processes: Bright Streaks and Dark Fans

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    In a region of the south pole known informally as 'Ithaca' numerous fans of dark frost form every spring. HiRISE collected a time lapse series of these images, starting at Ls = 185 and culminating at Ls = 294. 'Ls' is the way we measure time on Mars: at Ls = 180 the sun passes the equator on its way south; at Ls = 270 it reaches its maximum subsolar latitude and summer begins.

    In the earliest image (figure 1) fans are dark, but small narrow bright streaks can be detected. In the next image (figure 2), acquired at Ls = 187, just 106 hours later, dramatic differences are apparent. The dark fans are larger and the bright fans are more pronounced and easily detectable. The third image in the sequence shows no bright fans at all.

    We believe that the bright streaks are fine frost condensed from the gas exiting the vent. The conditions must be just right for the bright frost to condense.

    Observation Geometry Image PSP_002622_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 16-Feb-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 246.9 km (154.3 miles). At this distance the image scale is 49.4 cm/pixel (with 2 x 2 binning) so objects 148 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 05:46 PM and the scene is illuminated from the west with a solar incidence angle of 88 degrees, thus the sun was about 2 degrees above the horizon. At a solar longitude of 185.1 degrees, the season on Mars is Northern Autumn.

  16. Temporal Contrast Changes in Dark Slope Streaks on Mars

    NASA Astrophysics Data System (ADS)

    Chilton, Heather; Phillips, C. B.; Brown, A.; Fenton, L.

    2013-01-01

    Dark slope streaks on Mars are among the most active and dynamic processes observed on the planet's surface. While various formation models have been suggested [1][2][3], dust avalanches seem to best explain streak origin and characteristics[4][5]. New streaks have the highest contrast suggesting they fade over time. One theory for this is atmospheric dust fallout slowly raising the albedo of the surface exposed by the dust avalanche, progressively increasing streak albedo until the streak becomes indistinguishable from the surrounding surface. In this study, we attempt an initial evaluation of changes in streak brightness relative to surroundings with a first order correction for incidence angle[6]. CRISM images were identified for spatial overlap and temporal range, then further selected for image sets with well-matched viewing geometries. The 1 micron wavelength band was used to reduce atmospheric interference and brightness values then collected at multiple locations within and alongside individual streaks, with on-streak/off-streak pairs at points of similar elevation. Values were then divided by the cosine of the corresponding MOLA incidence angle for brightness variation correction due to topography. Measurements for overlapping images established local and overall averages for the rate of change in contrast ratio. Results showed a range of trends including streaks that darkened, brightened, brightened then darkened or vice versa. We continue to explore the possibility of non-linear brightening as well as streak reactivation and localized events, surface characteristics, and topography. Further study will focus on these and other morphological changes observed from vast data sets of other instruments including the Mars Reconnaissance Orbter HiRISE and CTX, Mars Express HRSC, Mars Odyssey THEMIS (visible), and the Mars Global Surveyor MOC. [1] Morris (1982) JGR, 87, 1164-1178. [2] Ferguson and Lucchita (1984) NASA Tech. Memo., TM-86246, 188-190. [3] Miyamoto

  17. Virus-independent and common transcriptome responses of leafhopper vectors feeding on maize infected with semi-persistently and persistent propagatively transmitted viruses

    PubMed Central

    2014-01-01

    Background Insects are the most important epidemiological factors for plant virus disease spread, with >75% of viruses being dependent on insects for transmission to new hosts. The black-faced leafhopper (Graminella nigrifrons Forbes) transmits two viruses that use different strategies for transmission: Maize chlorotic dwarf virus (MCDV) which is semi-persistently transmitted and Maize fine streak virus (MFSV) which is persistently and propagatively transmitted. To date, little is known regarding the molecular and cellular mechanisms in insects that regulate the process and efficiency of transmission, or how these mechanisms differ based on virus transmission strategy. Results RNA-Seq was used to examine transcript changes in leafhoppers after feeding on MCDV-infected, MFSV-infected and healthy maize for 4 h and 7 d. After sequencing cDNA libraries constructed from whole individuals using Illumina next generation sequencing, the Rnnotator pipeline in Galaxy was used to reassemble the G. nigrifrons transcriptome. Using differential expression analyses, we identified significant changes in transcript abundance in G. nigrifrons. In particular, transcripts implicated in the innate immune response and energy production were more highly expressed in insects fed on virus-infected maize. Leafhoppers fed on MFSV-infected maize also showed an induction of transcripts involved in hemocoel and cell-membrane linked immune responses within four hours of feeding. Patterns of transcript expression were validated for a subset of transcripts by quantitative real-time reverse transcription polymerase chain reaction using RNA samples collected from insects fed on healthy or virus-infected maize for between a 4 h and seven week period. Conclusions We expected, and found, changes in transcript expression in G. nigrifrons feeding of maize infected with a virus (MFSV) that also infects the leafhopper, including induction of immune responses in the hemocoel and at the cell membrane. The

  18. Semiclassical model for attosecond angular streaking.

    PubMed

    Smolarski, M; Eckle, P; Keller, U; Dörner, R

    2010-08-16

    Attosecond angular streaking is a new technique to achieve unsurpassed time accuracy of only a few attoseconds. Recently this has been successfully used to set an upper limit on the electron tunneling delay time in strong laser field ionization. The measurement technique can be modeled with either the time-dependent Schrödinger equation (TDSE) or a more simple semiclassical approach that describes the process in two steps in analogy to the three-step model in high harmonic generation (HHG): step one is the tunnel ionization and step two is the classical motion in the strong laser field. Here we describe in detail a semiclassical model which is based on the ADK theory for the tunneling step, with subsequent classical propagation of the electron in the laser field. We take into account different ellipticities of the laser field and a possible wavelength-dependent ellipticity that is typically observed for pulses in the two-optical-cycle regime. This semiclassical model shows excellent agreement with the experimental result. PMID:20721150

  19. Simulation of FEL pulse length calculation with THz streaking method.

    PubMed

    Gorgisyan, I; Ischebeck, R; Prat, E; Reiche, S; Rivkin, L; Juranić, P

    2016-05-01

    Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pump-probe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostics is the THz streak camera which is capable of simultaneously measuring the lengths of the photon pulses and their arrival times with respect to the pump laser. This work presents simulations of a THz streak camera performance. The simulation procedure utilizes FEL pulses with two different photon energies in hard and soft X-ray regions, respectively. It recreates the energy spectra of the photoelectrons produced by the photon pulses and streaks them by a single-cycle THz pulse. Following the pulse-retrieval procedure of the THz streak camera, the lengths were calculated from the streaked spectra. To validate the pulse length calculation procedure, the precision and the accuracy of the method were estimated for streaking configuration corresponding to previously performed experiments. The obtained results show that for the discussed setup the method is capable of measuring FEL pulses with about a femtosecond accuracy and precision. PMID:27140142

  20. Simulation of FEL pulse length calculation with THz streaking method

    PubMed Central

    Gorgisyan, I.; Ischebeck, R.; Prat, E.; Reiche, S.; Rivkin, L.; Juranić, P.

    2016-01-01

    Having accurate and comprehensive photon diagnostics for the X-ray pulses delivered by free-electron laser (FEL) facilities is of utmost importance. Along with various parameters of the photon beam (such as photon energy, beam intensity, etc.), the pulse length measurements are particularly useful both for the machine operators to measure the beam parameters and monitor the stability of the machine performance, and for the users carrying out pump–probe experiments at such facilities to better understand their measurement results. One of the most promising pulse length measurement techniques used for photon diagnostics is the THz streak camera which is capable of simultaneously measuring the lengths of the photon pulses and their arrival times with respect to the pump laser. This work presents simulations of a THz streak camera performance. The simulation procedure utilizes FEL pulses with two different photon energies in hard and soft X-ray regions, respectively. It recreates the energy spectra of the photoelectrons produced by the photon pulses and streaks them by a single-cycle THz pulse. Following the pulse-retrieval procedure of the THz streak camera, the lengths were calculated from the streaked spectra. To validate the pulse length calculation procedure, the precision and the accuracy of the method were estimated for streaking configuration corresponding to previously performed experiments. The obtained results show that for the discussed setup the method is capable of measuring FEL pulses with about a femtosecond accuracy and precision. PMID:27140142

  1. Study of Geometric Parameters of Slope Streaks on Mars.

    NASA Astrophysics Data System (ADS)

    Brusnikin, Eugene; Kreslavsky, Mikhail; Karachevtseva, Irina; Zubarev, Anatoliy; Patratiy, Vyacheslav

    2015-04-01

    Slope streaks are a unique active phenomenon observed in low-latitude dusty regions on Mars. They are dark markings formed by an unknown type of run-away downslope propagation of surface disturbance. There are two kinds of hypotheses of their formation mechanism: "dry", involving granular follow, in particular, dust avalanche, and "wet", involving liquid flow, in particular, percolation of concentrated brines in shallow subsurface (1). Study of geometric characteristics of the slope streaks, especially their slopes, is a way to decipher their origin. We are carrying out an extensive set of measurements of geometric parameters of the slope streaks. We use stereo pairs of images obtained by High Resolution Imaging Science Experiment (HiRISE) onboard MRO orbital mission to Mars. These stereo pairs potentially allow geometric measurements (both horizontal and vertical) with accuracy on an order of a meter. Unfortunately, the digital terrain model is currently released for only one stereo pair in the regions of slope streak occurrence, and we have to work with raw, unprocessed stereo pairs. We perform direct photogrammetric measurements using PHOTOMOD software complex (http://www.racurs.ru/). We use our custom software to import "raw" HiRISE imgas (EDRs) and supplementary geometric information from SPICE into PHOTOMOD (2). We select tens to a hundred meters long segments in the beginning and the end of selected streaks and register length, azimuth, and slope of each segment. We also search for anomalously gentle parts of streaks. We analyze the obtained results by means of ESRI ArcGIS software. Our survey is in progress. So far we registered over a hundred of streaks. We found that the extent of the streaks varies from several meters to hundreds of meters. The streaks are formed in locales with a slope from 17 to 37 degrees. The lower boundary indicates that the streaks can propagate on slopes that are significantly gentler than the static angle of repose. Distal

  2. RNAi-mediated resistance to Cassava brown streak Uganda virus in transgenic cassava.

    PubMed

    Yadav, Jitender S; Ogwok, Emmanuel; Wagaba, Henry; Patil, Basavaprabhu L; Bagewadi, Basavaraj; Alicai, Titus; Gaitan-Solis, Eliana; Taylor, Nigel J; Fauquet, Claude M

    2011-09-01

    Cassava brown streak disease (CBSD), caused by Cassava brown streak Uganda virus (CBSUV) and Cassava brown streak virus (CBSV), is of new epidemic importance to cassava (Manihot esculenta Crantz) production in East Africa, and an emerging threat to the crop in Central and West Africa. This study demonstrates that at least one of these two ipomoviruses, CBSUV, can be efficiently controlled using RNA interference (RNAi) technology in cassava. An RNAi construct targeting the near full-length coat protein (FL-CP) of CBSUV was expressed constitutively as a hairpin construct in cassava. Transgenic cassava lines expressing small interfering RNAs (siRNAs) against this sequence showed 100% resistance to CBSUV across replicated graft inoculation experiments. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed the presence of CBSUV in leaves and some tuberous roots from challenged controls, but not in the same tissues from transgenic plants. This is the first demonstration of RNAi-mediated resistance to the ipomovirus CBSUV in cassava. PMID:21726367

  3. Maize aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize is one of the most economically important food crops grown on acid soils, where aluminum (Al) toxicity greatly limits crop yields. Considerable variation for Al tolerance exists in maize, and this variation has been exploited for many years by plant breeders to enhance maize Al tolerance. Curr...

  4. Streak detection and analysis pipeline for optical images

    NASA Astrophysics Data System (ADS)

    Virtanen, J.; Granvik, M.; Torppa, J.; Muinonen, K.; Poikonen, J.; Lehti, J.; Säntti, T.; Komulainen, T.; Flohrer, T.

    2014-07-01

    We describe a novel data processing and analysis pipeline for optical observations of moving objects, either of natural (asteroids, meteors) or artificial origin (satellites, space debris). The monitoring of the space object populations requires reliable acquisition of observational data to support the development and validation of population models, and to build and maintain catalogues of orbital elements. The orbital catalogues are, in turn, needed for the assessment of close approaches (for asteroids, with the Earth; for satellites, with each other) and for the support of contingency situations or launches. For both types of populations, there is also increasing interest to detect fainter objects corresponding to the small end of the size distribution. We focus on the low signal-to-noise (SNR) detection of objects with high angular velocities, resulting in long and faint object trails, or streaks, in the optical images. The currently available, mature image processing algorithms for detection and astrometric reduction of optical data cover objects that cross the sensor field-of-view comparably slowly, and, particularly for satellites, within a rather narrow, predefined range of angular velocities. By applying specific tracking techniques, the objects appear point-like or as short trails in the exposures. However, the general survey scenario is always a 'track-before-detect' problem, resulting in streaks of arbitrary lengths. Although some considerations for low-SNR processing of streak-like features are available in the current image processing and computer vision literature, algorithms are not readily available yet. In the ESA-funded StreakDet (Streak detection and astrometric reduction) project, we develop and evaluate an automated processing pipeline applicable to single images (as compared to consecutive frames of the same field) obtained with any observing scenario, including space-based surveys and both low- and high-altitude populations. The algorithmic

  5. Responses of Maize (Zea mays L.) near isogenic lines carrying Wsm1, Wsm2 and Wsm3 to three viruses in the Potyviridae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three independent genes controlling resistance to Wheat streak mosaic virus (WSMV; family Potyviridae; genus Tritimovirus) were previously identified on chromosomes six (Wsm1), three (Wsm2) and ten (Wsm3) in the resistant maize (Zea mays L.) inbred line Pa405. Near isogenic lines (NIL) carrying eac...

  6. MaizeCyc: Metabolic networks in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeCyc is a catalog of known and predicted metabolic and transport pathways that enables plant researchers to graphically represent the metabolome of maize (Zea mays), thereby supporting integrated systems-biology analysis. Supported analyses include molecular and genetic/phenotypic profiling (e.g...

  7. Hitting Is Contagious in Baseball: Evidence from Long Hitting Streaks

    PubMed Central

    Bock, Joel R.; Maewal, Akhilesh; Gough, David A.

    2012-01-01

    Data analysis is used to test the hypothesis that “hitting is contagious”. A statistical model is described to study the effect of a hot hitter upon his teammates’ batting during a consecutive game hitting streak. Box score data for entire seasons comprising streaks of length games, including a total observations were compiled. Treatment and control sample groups () were constructed from core lineups of players on the streaking batter’s team. The percentile method bootstrap was used to calculate confidence intervals for statistics representing differences in the mean distributions of two batting statistics between groups. Batters in the treatment group (hot streak active) showed statistically significant improvements in hitting performance, as compared against the control. Mean for the treatment group was found to be to percentage points higher during hot streaks (mean difference increased points), while the batting heat index introduced here was observed to increase by points. For each performance statistic, the null hypothesis was rejected at the significance level. We conclude that the evidence suggests the potential existence of a “statistical contagion effect”. Psychological mechanisms essential to the empirical results are suggested, as several studies from the scientific literature lend credence to contagious phenomena in sports. Causal inference from these results is difficult, but we suggest and discuss several latent variables that may contribute to the observed results, and offer possible directions for future research. PMID:23251507

  8. Design and Field Test of a Galvanometer Deflected Streak Camera

    SciTech Connect

    Lai, C C; Goosman, D R; Wade, J T; Avara, R

    2002-11-08

    We have developed a compact fieldable optically-deflected streak camera first reported in the 20th HSPP Congress. Using a triggerable galvanometer that scans the optical signal, the imaging and streaking function is an all-optical process without incurring any photon-electron-photon conversion or photoelectronic deflection. As such, the achievable imaging quality is limited mainly only by optical design, rather than by multiple conversions of signal carrier and high voltage electron-optics effect. All core elements of the camera are packaged into a 12 inch x 24 inch footprint box, a size similar to that of a conventional electronic streak camera. At LLNL's Site-300 Test Site, we have conducted a Fabry-Perot interferometer measurement of fast object velocity using this all-optical camera side-by-side with an intensified electronic streak camera. These two cameras are configured as two independent instruments for recording synchronously each branch of the 50/50 splits from one incoming signal. Given the same signal characteristics, the test result has undisputedly demonstrated superior imaging performance for the all-optical streak camera. It produces higher signal sensitivity, wider linear dynamic range, better spatial contrast, finer temporal resolution, and larger data capacity as compared with that of the electronic counterpart. The camera had also demonstrated its structural robustness and functional consistence to be well compatible with field environment. This paper presents the camera design and the test results in both pictorial records and post-process graphic summaries.

  9. The Dellistrique 2S - A 200 Channel Streak Camera

    NASA Astrophysics Data System (ADS)

    Majumdar, S.

    1985-02-01

    Despite a great deal of effort to improve time resolution of streak cameras, the best reported time resolution remained just under one picosecond for more than a decade. However, the sensitivity and resolution of these devices have improved substantially over this time. In this paper the design of a very high performance streak camera, capable of resolving one picosecond on 200 parallel channels with single photo-electron detection capability: the Dellistrique 2S. The system comprises of a streak tube type Picotron 200 with a photocathode resolving 200 spatial channels along a slit and with an extraction field near the photocathode of greater than 16 KV per cm and with a non saturating phosphor screen as the main component. There is post streak tube intensification of 30,000 at the streak tube output wavelength which increases both the sensitivity of the system. The intensifier is coupled to a CCD readout device fibre-optically for producing a two dimensional image with a dynamic range of greater than 500. The camera can be operated at a repetition rate of between 80 MHz and 240 MHz using R.F. scanning methods. Upto 20 parallel channels have been tried with parallel information recording, which is well below the tube's capability of recording 200 independent channels. The image is virtually distortion free across the whole usable screen length of 45 mm for a large screen tube.

  10. Vascular Streak Dieback of cacao in Southeast Asia detection and Melanesia: in planta detection of the pathogen and a new taxonomy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vascular Streak Dieback (VSD) disease of cacao (Theobroma cacao) in Southeast Asia and Melanesia is caused by a basidiomycete (Ceratobasidiales) fungus described in a monotypic genus as Oncobasidium theobromae (syn. =Thanatephorus theobromae). The symptoms of the disease include green-spotted chloro...

  11. A time-resolved image sensor for tubeless streak cameras

    NASA Astrophysics Data System (ADS)

    Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

    2014-03-01

    This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

  12. Attosecond streaking in a nano-plasmonic field

    NASA Astrophysics Data System (ADS)

    Kelkensberg, F.; Koenderink, A. F.; Vrakking, M. J. J.

    2012-09-01

    A theoretical study of the application of attosecond streaking spectroscopy to time-resolved studies of the plasmonic fields surrounding isolated, resonantly excited spherical nanoparticles is presented. A classification of the different regimes in attosecond streaking is proposed and identified in our results that are derived from Mie calculations of plasmon fields, coupled to classical electron trajectory simulations. It is shown that in an attosecond streaking experiment, the electrons are almost exclusively sensitive to the component of the field parallel to the direction in which they are detected. This allows one to probe the different components of the field individually by resolving the angle of emission of the electrons. Finally, simulations based on fields calculated by finite-difference time-domain (FDTD) are compared with the results obtained using Mie fields. The two are found to be in good agreement with each other, supporting the notion that FDTD methods can be used to reliably investigate non-spherical structures.

  13. Mead Crater, Venus - Aerodynamic roughness of wind streaks

    NASA Astrophysics Data System (ADS)

    Williams, K. K.; Greeley, R.

    1997-03-01

    Radar backscatter images of Venus returned by the Magellan spacecraft revealed many aeolian features on the planet's surface. While much work has focused on terrestrial wind streaks, the harsh environment of Venus limits direct measurement of surface properties, such as aerodynamic roughness, that affect aeolian features on that planet. However, a correlation between radar backscatter and aerodynamic roughness (Z0) for the S-band radar system on Magellan can be used to study the aerodynamic roughnesses of areas in which Venusian wind streaks occur. The aerodynamic roughness of areas with both radar-bright and radar-dark wind streaks near Mead crater are calculated and compared to z0 values measured on Earth in order to compare the surface of Venus with known terrestrial surface textures.

  14. Streak Camera Performance with Large-Format CCD Readout

    SciTech Connect

    Lerche, R A; Andrews, D S; Bell, P M; Griffith, R L; McDonald, J W; Torres, P III; Vergel de Dios, G

    2003-07-08

    The ICF program at Livermore has a large inventory of optical streak cameras that were built in the 1970s and 1980s. The cameras include micro-channel plate image-intensifier tubes (IIT) that provide signal amplification and early lens-coupled CCD readouts. Today, these cameras are still very functional, but some replacement parts such as the original streak tube, CCD, and IIT are scarce and obsolete. This article describes recent efforts to improve the performance of these cameras using today's advanced CCD readout technologies. Very sensitive, large-format CCD arrays with efficient fiber-optic input faceplates are now available for direct coupling with the streak tube. Measurements of camera performance characteristics including linearity, spatial and temporal resolution, line-spread function, contrast transfer ratio (CTR), and dynamic range have been made for several different camera configurations: CCD coupled directly to the streak tube, CCD directly coupled to the IIT, and the original configuration with a smaller CCD lens coupled to the IIT output. Spatial resolution (limiting visual) with and without the IIT is 8 and 20 lp/mm, respectively, for photocathode current density up to 25% of the Child-Langmuir (C-L) space-charge limit. Temporal resolution (fwhm) deteriorates by about 20% when the cathode current density reaches 10% of the C-L space charge limit. Streak tube operation with large average tube current was observed by illuminating the entire slit region through a Ronchi ruling and measuring the CTR. Sensitivity (CCD electrons per streak tube photoelectron) for the various configurations ranged from 7.5 to 2,700 with read noise of 7.5 to 10.5 electrons. Optimum spatial resolution is achieved when the IIT is removed. Maximum dynamic range requires a configuration where a single photoelectron from the photocathode produces a signal that is 3 to 5 times the read noise.

  15. Breeding for Improved Resistance to Fumonisin Contamination in Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize grain infected by Fusarium verticillioides may contain the mycotoxin fumonisin, which is associated with livestock and human diseases. To reduce levels of fumonisin in grain, efforts are underway to identify sources of maize with increased resistance to fungal infection and fumonisin contamin...

  16. Wheat streak mosaic virus-Structural parameters for a Potyvirus

    SciTech Connect

    Parker, Lauren; Kendall, Amy; Berger, P.H.; Shiel, P.J.; Stubbs, Gerald . E-mail: gerald.stubbs@vanderbilt.edu

    2005-09-15

    Wheat streak mosaic virus is a Tritimovirus, a member of the Potyviridae family, which includes the very large Potyvirus genus. We have examined wheat streak mosaic virus by electron microscopy and fiber diffraction from partially oriented sols, and analyzed the results to estimate the symmetry and structural parameters of the viral helix. The virions have an apparent radius of 63 {+-} 5 A. The viral helix has a pitch of 33.4 A {+-} 0.6 A. There appear to be 6.9 subunits per turn of the helix, although we cannot completely eliminate values of 5.9 or 7.9 for this parameter.

  17. Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) would likely be under positive selection pressure. We examined the novel proposition that naturally occurring allelic variants may confer MDR. To do so, we applied a ...

  18. Hot streaks and phantom cooling in a turbine rotor passage. I - Separate effects

    NASA Technical Reports Server (NTRS)

    Roback, Richard J.; Dring, Robert P.

    1992-01-01

    Experimental documentation and analytical correlations demonstrating the effects of hot streak accumulation and phantom cooling on turbine rotor airfoil surface temperature. Test results are shown for a range of controlling variables to identify where streak accumulation and phantom cooling are most likely to be strongest. These variables include streak injection location, streak-to-free stream density ratio and coolant-to-free stream density and velocity ratios.

  19. Cellular Tracking and Gene Profiling of Fusarium graminearum during Maize Stalk Rot Disease Development Elucidates Its Strategies in Confronting Phosphorus Limitation in the Host Apoplast

    PubMed Central

    Jia, Lei-Jie; Yuan, Ting-Lu; Zhang, Dong; Guo, Yan; Wang, Yufeng; Tang, Wei-Hua

    2016-01-01

    The ascomycete fungus Fusarium graminearum causes stalk rot in maize. We tracked this pathogen’s growth in wound-inoculated maize stalks using a fluorescence-labeled fungal isolate and observed that invasive hyphae grew intercellularly up to 24 h post inoculation, grew intra- and inter-cellularly between 36–48 h, and fully occupied invaded cells after 72 h. Using laser microdissection and microarray analysis, we profiled changes in global gene expression during pathogen growth inside pith tissues of maize stalk from 12 h to six days after inoculation and documented transcriptomic patterns that provide further insights into the infection process. Expression changes in transcripts encoding various plant cell wall degrading enzymes appeared to correlate with inter- and intracellular hyphal growth. Genes associated with 36 secondary metabolite biosynthesis clusters were expressed. Expression of several F. graminearum genes potentially involved in mobilization of the storage lipid triacylglycerol and phosphorus-free lipid biosynthesis were induced during early infection time points, and deletion of these genes caused reduction of virulence in maize stalk. Furthermore, we demonstrated that the F. graminearum betaine lipid synthase 1 (BTA1) gene was necessary and sufficient for production of phosphorus-free membrane lipids, and that deletion of BTA1 interfered with F. graminearum’s ability to advance intercellularly. We conclude that F. graminearum produces phosphorus-free membrane lipids to adapt to a phosphate-limited extracellular microenvironment during early stages of its invasion of maize stalk. PMID:26974960

  20. Cellular Tracking and Gene Profiling of Fusarium graminearum during Maize Stalk Rot Disease Development Elucidates Its Strategies in Confronting Phosphorus Limitation in the Host Apoplast.

    PubMed

    Zhang, Yan; He, Juan; Jia, Lei-Jie; Yuan, Ting-Lu; Zhang, Dong; Guo, Yan; Wang, Yufeng; Tang, Wei-Hua

    2016-03-01

    The ascomycete fungus Fusarium graminearum causes stalk rot in maize. We tracked this pathogen's growth in wound-inoculated maize stalks using a fluorescence-labeled fungal isolate and observed that invasive hyphae grew intercellularly up to 24 h post inoculation, grew intra- and inter-cellularly between 36-48 h, and fully occupied invaded cells after 72 h. Using laser microdissection and microarray analysis, we profiled changes in global gene expression during pathogen growth inside pith tissues of maize stalk from 12 h to six days after inoculation and documented transcriptomic patterns that provide further insights into the infection process. Expression changes in transcripts encoding various plant cell wall degrading enzymes appeared to correlate with inter- and intracellular hyphal growth. Genes associated with 36 secondary metabolite biosynthesis clusters were expressed. Expression of several F. graminearum genes potentially involved in mobilization of the storage lipid triacylglycerol and phosphorus-free lipid biosynthesis were induced during early infection time points, and deletion of these genes caused reduction of virulence in maize stalk. Furthermore, we demonstrated that the F. graminearum betaine lipid synthase 1 (BTA1) gene was necessary and sufficient for production of phosphorus-free membrane lipids, and that deletion of BTA1 interfered with F. graminearum's ability to advance intercellularly. We conclude that F. graminearum produces phosphorus-free membrane lipids to adapt to a phosphate-limited extracellular microenvironment during early stages of its invasion of maize stalk. PMID:26974960

  1. Processing Particle-Streak Imagery On A Personal Computer

    NASA Technical Reports Server (NTRS)

    Cho, Y. C.; Mclachlan, B. G.

    1991-01-01

    Report describes simple flow experiment in which streak images of particles suspended in fluid and illuminated for short times processed into maps of velocity vectors. In experiment, semiautomatic data-reduction scheme used which recovers significant image data more efficiently than currently available automatic scheme.

  2. Soft x-ray streak camera for laser fusion applications

    SciTech Connect

    Stradling, G.L.

    1981-04-01

    This thesis reviews the development and significance of the soft x-ray streak camera (SXRSC) in the context of inertial confinement fusion energy development. A brief introduction of laser fusion and laser fusion diagnostics is presented. The need for a soft x-ray streak camera as a laser fusion diagnostic is shown. Basic x-ray streak camera characteristics, design, and operation are reviewed. The SXRSC design criteria, the requirement for a subkilovolt x-ray transmitting window, and the resulting camera design are explained. Theory and design of reflector-filter pair combinations for three subkilovolt channels centered at 220 eV, 460 eV, and 620 eV are also presented. Calibration experiments are explained and data showing a dynamic range of 1000 and a sweep speed of 134 psec/mm are presented. Sensitivity modifications to the soft x-ray streak camera for a high-power target shot are described. A preliminary investigation, using a stepped cathode, of the thickness dependence of the gold photocathode response is discussed. Data from a typical Argus laser gold-disk target experiment are shown.

  3. Silent polypoidal choroidal vasculopathy in a patient with angioid streaks.

    PubMed

    Cebeci, Zafer; Bayraktar, Serife; Oray, Merih; Kir, Nur

    2016-01-01

    We present a case of silent polypoidal choroidal vasculopathy (PCV) in a patient with angioid streaks. PCV was detected during a routine ophthalmic examination and confirmed by fluorescein angiography, indocyanine green angiography, and optical coherence tomography. After 2 years of follow-up, the PCV remained silent without any complications. We report this rare coexistence and review literature on this topic. PMID:27463636

  4. Improved approach to characterizing and presenting streak camera performance

    SciTech Connect

    Wiedwald, J.D.; Jones, B.A.

    1985-07-15

    The performance of a streak camera recording system is strongly linked to the technique used to amplify, detect and quantify the streaked image. At the Lawrence Livermore National Laboratory (LLNL) streak camera images have been recorded both on film and by fiber-optically coupling to charge-coupled devices (CCD's). During the development of a new process for recording these images (lens coupling the image onto a cooled CCD) the definitions of important performance characteristics such as resolution and dynamic range were re-examined. As a result of this development, these performance characteristics are now presented to the streak camera user in a more useful format than in the past. This paper describes how these techniques are used within the Laser Fusion Program at LLNL. The system resolution is presented as a modulation transfer function, including the seldom reported effects that flare and light scattering have at low spatial frequencies. Data are presented such that a user can adjust image intensifier gain and pixel averaging to optimize the useful dynamic range in any particular application.

  5. Analysis of hot streak effects on turbine rotor heat load

    SciTech Connect

    Shang, T.; Epstein, A.H.

    1997-07-01

    The influence of inlet hot streak temperature distortion on turbine blade heat load was explored on a transonic axial flow turbine stage test article using a three-dimensional, multiblade row unsteady Euler code. The turbine geometry was the same as that used for a recently reported testing of hot streak influence. Emphasis was placed on elucidating the physical and mechanisms by which hot streaks affect turbine durability. It was found that temperature distortion significantly increases both blade surface heat load nonuniformity and total blade heat load by as much as 10--30% (mainly in the pressure surface), and that the severity of this influence is a strong function of turbine geometry and flow conditions. Three physical mechanisms were identified that drive the heat load nonuniformity: buoyancy, wake convection (the Kerrebrock-Mikolajczak effect), and rotor-stator interactions. The latter can generate significant nonuniformity of the time-averaged relative frame rotor inlet temperature distribution. Dependence of these effects on turbine design variables was investigated to shed light on the design space, which minimizes the adverse effects of hot streaks.

  6. Attosecond time-resolved streaked photoemission from solids

    NASA Astrophysics Data System (ADS)

    Liao, Qing; Thumm, Uwe

    2015-05-01

    We established a quantum-mechanical model for infrared (IR) laser streaked photoelectron (PE) emission from metal solids by an ultrashort extreme ultraviolet (XUV) pulse. Special emphasis was laid on the influence of the energy dispersion of PEs inside the solids on the photoemission time delay. We first applied this model to Mg(0001) surfaces, assuming free-electron dispersion and found good agreement with measured streaked PE spectra and streaking time delays. Next, we investigate W(110) surfaces for which non-free PE dispersion must be included in order to reproduce the measured photoemission delays at different XUV central photon energies. Our model reproduces a series of measured streaked spectrograms and photoemission delays for different metal solids, including clean Mg(0001) and W(110) surfaces and Mg-covered W(110) surfaces. It incorporates modeling of the target band structure, electron mean free paths, energy dispersion, and screening of the IR laser field on the surface. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy under Grant No. DE-FG02-86ER13491 and NSF Grant PHY-1068752.

  7. Reliable and Repeatable Characterization of Optical Streak Cameras

    SciTech Connect

    Michael Charest Jr., Peter Torres III, Christopher Silbernagel, and Daniel Kalantar

    2008-10-31

    Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

  8. Reliable and Repeatable Characterication of Optical Streak Cameras

    SciTech Connect

    Kalantar, D; Charest, M; Torres III, P; Charest, M

    2008-05-06

    Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

  9. Hitting is contagious in baseball: evidence from long hitting streaks.

    PubMed

    Bock, Joel R; Maewal, Akhilesh; Gough, David A

    2012-01-01

    Data analysis is used to test the hypothesis that "hitting is contagious". A statistical model is described to study the effect of a hot hitter upon his teammates' batting during a consecutive game hitting streak. Box score data for entire seasons comprising [Formula: see text] streaks of length [Formula: see text] games, including a total [Formula: see text] observations were compiled. Treatment and control sample groups ([Formula: see text]) were constructed from core lineups of players on the streaking batter's team. The percentile method bootstrap was used to calculate [Formula: see text] confidence intervals for statistics representing differences in the mean distributions of two batting statistics between groups. Batters in the treatment group (hot streak active) showed statistically significant improvements in hitting performance, as compared against the control. Mean [Formula: see text] for the treatment group was found to be [Formula: see text] to [Formula: see text] percentage points higher during hot streaks (mean difference increased [Formula: see text] points), while the batting heat index [Formula: see text] introduced here was observed to increase by [Formula: see text] points. For each performance statistic, the null hypothesis was rejected at the [Formula: see text] significance level. We conclude that the evidence suggests the potential existence of a "statistical contagion effect". Psychological mechanisms essential to the empirical results are suggested, as several studies from the scientific literature lend credence to contagious phenomena in sports. Causal inference from these results is difficult, but we suggest and discuss several latent variables that may contribute to the observed results, and offer possible directions for future research. PMID:23251507

  10. The Symptom and Genetic Diversity of Cassava Brown Streak Viruses Infecting Cassava in East Africa

    PubMed Central

    Mohammed, I. U.; Abarshi, M. M.; Muli, B.; Hillocks, R. J.; Maruthi, M. N.

    2012-01-01

    The genetic and symptom diversity of six virus isolates causing cassava brown streak disease (CBSD) in the endemic (Kenya, Mozambique, and Tanzania) and the recently affected epidemic areas (Uganda) of eastern Africa was studied. Five cassava varieties; Albert, Colombian, Ebwanateraka, TMS60444 (all susceptible) and Kiroba (tolerant) were graft inoculated with each isolate. Based on a number of parameters including the severity of leaf and root symptoms, and the extent of virus transmission by grafting, the viruses were classified as either severe or relatively mild. These results were further confirmed by the mechanical inoculation of 13 herbaceous hosts in which the virulent isolates caused plant death in Nicotiana clevelandii and N. benthamiana whereas the milder isolates did not. Phylogenetic analysis of complete coat protein gene sequences of these isolates together with sequences obtained from 14 other field-collected samples from Kenya and Zanzibar, and reference sequences grouped them into two distinct clusters, representing the two species of cassava brown streak viruses. Put together, these results did not suggest the association of a hypervirulent form of the virus with the current CBSD epidemic in Uganda. Identification of the severe and milder isolates, however, has further implications for disease management and quarantine requirements. PMID:22454639

  11. Effect of Amirkabiria odorastissima mozaffarian on the development and progression of fatty streaks in hypercholesterolemic rabbits.

    PubMed

    Asgary, S; Naderi, Gh; Dashti, Gh; Paknahad, Z

    2004-05-01

    New studies have introduced atherosclerosis as an inflammatory disease. Different factors affect the development of inflammation that can be linked to free radicals, hypertention, diabetes mellitus, genetic changes, hypercholesterolemia and some of the microorganisms. Using anti-inflammatory drugs can be useful in preventing atherosclerosis. Finding drugs from natural sources and without side-effects can be useful. Amirkabiria odoratissima (umbelliferae) is from Iranian fl ora and is used traditionally as an anti-inflammatory drug. This study was designed to assess the effects of this plant on the development and progression of fatty streaks. Male rabbits were fed: (a) rabbit chow; (b) 1% cholesterol diet; (c) cholesterol diet supplemented with the plant; (d) normal diet supplemented with the plant. After 12 weeks, the animals were sacrificed and the aorta, right and left branches of coronary arteries were dissected and histologically processed. Before and after the end of the study, biochemical factors were measured. The amounts of cholesterol, LDL, HDL, triglyceride and fasting blood sugar (FBS) were determined by enzymatic methods, quantitative CRP was determined by turbidimetric methods, malondialdehyde (MDA) and antioxidant capacity were determined by speceterophotometric methods. The results indicate that there is a significant difference between the groups supplemented with herbal medicine and others (p < 0.05) in the mean grade of fatty streak of right and left coronary artery and aorta. At the end of the 12-week period cholesterol, LDL and CRP were significantly reduced in the groups which received herbal medicine (p < 0.05). The data suggests that Amirkabiria odoratissima Mozaffarian has beneficial effects to prevent development of fatty streak; however, further studies are needed to understand the mechanisms whereby this plant exerts its anti-atherosclerotic effects. PMID:15173995

  12. Ipomoviruses: Squash vein yellowing virus, Cucumber vein yellowing virus, Cassava brown streak virus, and Ugandan cassava brown streak virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ipomoviruses including Squash vein yellowing virus, Cucumber vein yellowing virus and Cassava brown streak virus are currently causing significant economic impact on crop production in several regions of the world. Only recently have results of detailed characterization of their whitefly transmissi...

  13. MaizeGDB, the maize model organism database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the maize research community's database for maize genetic and genomic information. In this seminar I will outline our current endeavors including a full website redesign, the status of maize genome assembly and annotation projects, and work toward genome functional annotation. Mechanis...

  14. Monitoring Nonadiabatic Electron-Nuclear Dynamics in Molecules by Attosecond Streaking of Photoelectrons.

    PubMed

    Kowalewski, Markus; Bennett, Kochise; Rouxel, Jérémy R; Mukamel, Shaul

    2016-07-22

    Streaking of photoelectrons has long been used for the temporal characterization of attosecond extreme ultraviolet pulses. When the time-resolved photoelectrons originate from a coherent superposition of electronic states, they carry additional phase information, which can be retrieved by the streaking technique. In this contribution we extend the streaking formalism to include coupled electron and nuclear dynamics in molecules as well as initial coherences. We demonstrate how streaked photoelectrons offer a novel tool for monitoring nonadiabatic dynamics as it occurs in the vicinity of conical intersections and avoided crossings. Streaking can provide high time resolution direct signatures of electronic coherences, which affect many primary photochemical and biological events. PMID:27494470

  15. Monitoring Nonadiabatic Electron-Nuclear Dynamics in Molecules by Attosecond Streaking of Photoelectrons

    NASA Astrophysics Data System (ADS)

    Kowalewski, Markus; Bennett, Kochise; Rouxel, Jérémy R.; Mukamel, Shaul

    2016-07-01

    Streaking of photoelectrons has long been used for the temporal characterization of attosecond extreme ultraviolet pulses. When the time-resolved photoelectrons originate from a coherent superposition of electronic states, they carry additional phase information, which can be retrieved by the streaking technique. In this contribution we extend the streaking formalism to include coupled electron and nuclear dynamics in molecules as well as initial coherences. We demonstrate how streaked photoelectrons offer a novel tool for monitoring nonadiabatic dynamics as it occurs in the vicinity of conical intersections and avoided crossings. Streaking can provide high time resolution direct signatures of electronic coherences, which affect many primary photochemical and biological events.

  16. Maize Genetic Resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter describes the resources held at the Maize Genetics Cooperation • Stock Center in detail and also provides some information about the North Central Regional Plant Introduction Station (NCRPIS) in Ames, IA, Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) in Mexico, and the N...

  17. Sorghum and Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorghum and maize are closely related cereal grains grown throughout the world. Sorghum, a drought tolerant crop grown in semi-arid regions, is a basic food staple in many parts of the developing world, while primarily an animal feed in western countries. Maize, a major worldwide crop, is used for...

  18. MAIZE ALLELIC DIVERSITY PROJECT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Of the estimated 250-300 races of maize, only 24 races are represented in materials utilized by the Germplasm Enhancement of Maize (GEM) project, a collaborative effort between USDA-ARS and public and private sector research scientists. This is largely a result of poor performance of many races in ...

  19. Identification of multiple ear-colonizing insect and disease resistance in CIMMYT maize inbred lines with varying levels of silk maysin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ninety four corn inbred lines selected from International Center for the Improvement of Maize and Wheat (CIMMYT) in Mexico were evaluated for levels of silk maysin in 2001 and 2002. Damage by major ear-feeding insects [i.e., the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), the m...

  20. First report of Maize chlorotic mottle virus and maize (corn) lethal necrosis in Kenya

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In September 2011, high incidence of a new maize (Zea mays L.) disease was reported at lower elevations (1900 masl) in the Longisa division of Bomet County, Southern Rift Valley of Kenya. Later the disease was noted in Bomet Central division, spreading into the neighboring Chepalungu and Narok South...

  1. Maize Lethal Necrosis (MLN), an Emerging Threat to Maize-Based Food Security in Sub-Saharan Africa.

    PubMed

    Mahuku, George; Lockhart, Benham E; Wanjala, Bramwel; Jones, Mark W; Kimunye, Janet Njeri; Stewart, Lucy R; Cassone, Bryan J; Sevgan, Subramanian; Nyasani, Johnson O; Kusia, Elizabeth; Kumar, P Lava; Niblett, C L; Kiggundu, Andrew; Asea, Godfrey; Pappu, Hanu R; Wangai, Anne; Prasanna, Boddupalli M; Redinbaugh, Margaret G

    2015-07-01

    In sub-Saharan Africa, maize is a staple food and key determinant of food security for smallholder farming communities. Pest and disease outbreaks are key constraints to maize productivity. In September 2011, a serious disease outbreak, later diagnosed as maize lethal necrosis (MLN), was reported on maize in Kenya. The disease has since been confirmed in Rwanda and the Democratic Republic of Congo, and similar symptoms have been reported in Tanzania, Uganda, South Sudan, and Ethiopia. In 2012, yield losses of up to 90% resulted in an estimated grain loss of 126,000 metric tons valued at $52 million in Kenya alone. In eastern Africa, MLN was found to result from coinfection of maize with Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV), although MCMV alone appears to cause significant crop losses. We summarize here the results of collaborative research undertaken to understand the biology and epidemiology of MLN in East Africa and to develop disease management strategies, including identification of MLN-tolerant maize germplasm. We discuss recent progress, identify major issues requiring further research, and discuss the possible next steps for effective management of MLN. PMID:25822185

  2. Development of streak camera with anisotropic focusing electron optical system

    NASA Astrophysics Data System (ADS)

    Tian, J.; Ding, Y.; Cao, X.; Liu, S.; Xu, X.; Hu, X.; Wen, W.; Wang, J.; Wang, C.; Liu, H.; Dong, G.; Zhang, T.; Lu, Y.; Wang, Xi.; Liu, J.

    2013-05-01

    In this paper, the anisotropic focusing technique is used to make a novel streak tube. The salient features are the introduction of both temporally focusing electrodes and spatially focusing electric quadrupole lens. The simulation showed that physical temporal dispersion of 0.38 ps and edge spatial resolution of 56 lp/mm can be achieved. The Nd:YLF 8ps pulse laser was used to calibrate the performance index of streak camera. The static and dynamic spatial resolutions are 35 lp/mm and 25 lp/mm respectively. The dynamic range more than 950:1 and time resolution 8ps can be reached. Furthermore, the magnifications in slit and scanning direction can be adjusted respectively, so it is very convenient to select amplification needed when it is coupled with KB microscope.

  3. Megahertz streak-mode Fourier domain optical coherence tomography

    PubMed Central

    Wang, Rui; Yun, Julie X.; Yuan, Xiaocong; Goodwin, Richard; Markwald, Roger R.; Gao, Bruce Z.

    2011-01-01

    Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz resonant scanner as the streak scanner, 1,016,000 A-scans have been obtained in 1 s. This method's effectiveness has been demonstrated by recording in vivo OCT-image sequences of embryonic chick hearts at 1000 frames/s. In addition, 2-megahertz OCT data have been obtained with another high speed camera. PMID:21721817

  4. Streak cameras for soft x-ray and optical radiation

    SciTech Connect

    Medecki, H.

    1983-09-01

    The principal component of a streak camera is the image converter tube. A slit-shaped photocathode transforms the radiation into a proportional emission of electrons. An electron - optics arrangement accelerates the electrons and projects them into a phosphor screen creating the image of the slit. A pair of deflection plates deflects the electronic beam along a direction perpendicular to the main dimension of the slit. Different portions of the phosphor screen show the instantaneous image of the slit with brightness proportional to the number of emitted electrons and, consequently, to the intensity of the radiation. For our x-ray streak cameras, we use the RCA C73435A image conventer tube intended for the measurement of the radiation of light and modified to have an x-ray sensitive photocathode. Practical considerations lead to the use of transparent rather than reflecting photocathodes. Several of these camera tubes are briefly described.

  5. rf streak camera based ultrafast relativistic electron diffraction.

    PubMed

    Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Tran, T

    2009-01-01

    We theoretically and experimentally investigate the possibility of using a rf streak camera to time resolve in a single shot structural changes at the sub-100 fs time scale via relativistic electron diffraction. We experimentally tested this novel concept at the UCLA Pegasus rf photoinjector. Time-resolved diffraction patterns from thin Al foil are recorded. Averaging over 50 shots is required in order to get statistics sufficient to uncover a variation in time of the diffraction patterns. In the absence of an external pump laser, this is explained as due to the energy chirp on the beam out of the electron gun. With further improvements to the electron source, rf streak camera based ultrafast electron diffraction has the potential to yield truly single shot measurements of ultrafast processes. PMID:19191429

  6. Viruses in maize and johnsongrass in southern ohio.

    PubMed

    Stewart, L R; Teplier, R; Todd, J C; Jones, M W; Cassone, B J; Wijeratne, S; Wijeratne, A; Redinbaugh, M G

    2014-12-01

    ABSTRACT The two major U.S. maize viruses, Maize dwarf mosaic virus (MDMV) and Maize chlorotic dwarf virus (MCDV), emerged in southern Ohio and surrounding regions in the 1960s and caused significant losses. Planting resistant varieties and changing cultural practices has dramatically reduced virus impact in subsequent decades. Current information on the distribution, diversity, and impact of known and potential U.S. maize disease-causing viruses is lacking. To assess the current reservoir of viruses present at the sites of past disease emergence, we used a combination of serological testing and next-generation RNA sequencing approaches. Here, we report enzyme-linked immunosorbent assay and RNA-Seq data from samples collected over 2 years to assess the presence of viruses in cultivated maize and an important weedy reservoir, Johnsongrass (Sorghum halepense). Results revealed a persistent reservoir of MDMV and two strains of MCDV in Ohio Johnsongrass. We identified sequences of several other grass-infecting viruses and confirmed the presence of Wheat mosaic virus in Ohio maize. Together, these results provide important data for managing virus disease in field corn and sweet corn maize crops, and identifying potential future virus threats. PMID:24918609

  7. 9. VIEW OF 'BLUE STREAK' HAMMER MILL (Prater Pulverizer Co., ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. VIEW OF 'BLUE STREAK' HAMMER MILL (Prater Pulverizer Co., Chicago, Illinois), LOCATED IN THE SOUTHEAST CORNER OF THE BASEMENT, WAS ADDED IN THE EARLY 1930s. THIS WAS THE MILL'S FIRST ELECTRIC-POWERED MACHINERY. THE HAMMER MILL WAS USED TO PULVERIZE OATS, ALFALFA MEAL, AND CORN. Photographer: Louise Taft Cawood, July 1986 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH

  8. Bacterial endophytes from wild maize suppress Fusarium graminearum in modern maize and inhibit mycotoxin accumulation

    PubMed Central

    Mousa, Walaa K.; Shearer, Charles R.; Limay-Rios, Victor; Zhou, Ting; Raizada, Manish N.

    2015-01-01

    Wild maize (teosinte) has been reported to be less susceptible to pests than their modern maize (corn) relatives. Endophytes, defined as microbes that inhabit plants without causing disease, are known for their ability to antagonize plant pests and pathogens. We hypothesized that the wild relatives of modern maize may host endophytes that combat pathogens. Fusarium graminearum is the fungus that causes Gibberella Ear Rot (GER) in modern maize and produces the mycotoxin, deoxynivalenol (DON). In this study, 215 bacterial endophytes, previously isolated from diverse maize genotypes including wild teosintes, traditional landraces and modern varieties, were tested for their ability to antagonize F. graminearum in vitro. Candidate endophytes were then tested for their ability to suppress GER in modern maize in independent greenhouse trials. The results revealed that three candidate endophytes derived from wild teosintes were most potent in suppressing F. graminearum in vitro and GER in a modern maize hybrid. These wild teosinte endophytes could suppress a broad spectrum of fungal pathogens of modern crops in vitro. The teosinte endophytes also suppressed DON mycotoxin during storage to below acceptable safety threshold levels. A fourth, less robust anti-fungal strain was isolated from a modern maize hybrid. Three of the anti-fungal endophytes were predicted to be Paenibacillus polymyxa, along with one strain of Citrobacter. Microscopy studies suggested a fungicidal mode of action by all four strains. Molecular and biochemical studies showed that the P. polymyxa strains produced the previously characterized anti-Fusarium compound, fusaricidin. Our results suggest that the wild relatives of modern crops may serve as a valuable reservoir for endophytes in the ongoing fight against serious threats to modern agriculture. We discuss the possible impact of crop evolution and domestication on endophytes in the context of plant defense. PMID:26500660

  9. Bacterial endophytes from wild maize suppress Fusarium graminearum in modern maize and inhibit mycotoxin accumulation.

    PubMed

    Mousa, Walaa K; Shearer, Charles R; Limay-Rios, Victor; Zhou, Ting; Raizada, Manish N

    2015-01-01

    Wild maize (teosinte) has been reported to be less susceptible to pests than their modern maize (corn) relatives. Endophytes, defined as microbes that inhabit plants without causing disease, are known for their ability to antagonize plant pests and pathogens. We hypothesized that the wild relatives of modern maize may host endophytes that combat pathogens. Fusarium graminearum is the fungus that causes Gibberella Ear Rot (GER) in modern maize and produces the mycotoxin, deoxynivalenol (DON). In this study, 215 bacterial endophytes, previously isolated from diverse maize genotypes including wild teosintes, traditional landraces and modern varieties, were tested for their ability to antagonize F. graminearum in vitro. Candidate endophytes were then tested for their ability to suppress GER in modern maize in independent greenhouse trials. The results revealed that three candidate endophytes derived from wild teosintes were most potent in suppressing F. graminearum in vitro and GER in a modern maize hybrid. These wild teosinte endophytes could suppress a broad spectrum of fungal pathogens of modern crops in vitro. The teosinte endophytes also suppressed DON mycotoxin during storage to below acceptable safety threshold levels. A fourth, less robust anti-fungal strain was isolated from a modern maize hybrid. Three of the anti-fungal endophytes were predicted to be Paenibacillus polymyxa, along with one strain of Citrobacter. Microscopy studies suggested a fungicidal mode of action by all four strains. Molecular and biochemical studies showed that the P. polymyxa strains produced the previously characterized anti-Fusarium compound, fusaricidin. Our results suggest that the wild relatives of modern crops may serve as a valuable reservoir for endophytes in the ongoing fight against serious threats to modern agriculture. We discuss the possible impact of crop evolution and domestication on endophytes in the context of plant defense. PMID:26500660

  10. Angioid streaks - a rare cause of neovascular glaucoma. Case report.

    PubMed

    Ungureanu, E; Geamanu, A; Careba, I; Grecescu, M; Gradinaru, S

    2014-01-01

    Rationale. Neovascular glaucoma is the type of glaucoma most refractory to treatment. The most frequent causes are those associated with retinal hypoxia, such as proliferative diabetic retinopathy, central retinal vein occlusion, branch retinal vein occlusion, central retinal arterial occlusion, ischemic ocular syndrome etc. Rare causes of neovascular glaucoma are multiple and are due to VEGF synthesis associated with chorioretinal inflammations or degenerations. We present a case with neovascular glaucoma associated with an extremely rare cause, angioid streaks Objective. The objective of our prsentation was to asses efficacy of the 5-FU associated trabeculectomy following bevacizumab intravitreal administration Methods and results. Case report of a 48 years old female patient which presented at the emergency room with painful red left eye. At presentation best corrected left eye visual acuity was 1/10, intraocular pressure was 36 mm Hg. Examination established the diagnosis of Neovascular glaucoma associated with angioid streaks. After intravenous Manitol, oral Acetazolamide and topical treatment with fixed combination timolol-brinzolamide, topical steroid and mydriatic intraocular pressure decreased. Intravitreal bevacizumab injection was performed, followed after 3 weeks by trabeculectomy. Discussion. Angioid streaks are an extremely rare cause of neovascular glaucoma. The treatment is similar to the treatment for other causes of neovascular glaucoma. PMID:27057253

  11. Automatic coil selection for streak artifact reduction in radial MRI.

    PubMed

    Xue, Yiqun; Yu, Jiangsheng; Kang, Hyun Seon; Englander, Sarah; Rosen, Mark A; Song, Hee Kwon

    2012-02-01

    In radial MR imaging, streaking artifacts contaminating the entire field of view can arise from regions at the outer edges of the prescribed field of view. This can occur even when the Nyquist criterion is satisfied within the desired field of view. These artifacts become exacerbated when parts of the object lie in the superior/inferior regions of the scanner where the gradient strengths become weakened. When multiple coil arrays are used for signal reception, coils at the outer edges can be disabled before data acquisition to reduce the artifact levels. However, as the weakened gradient strengths near the edges often distort the object, causing the signal to become highly concentrated into a small region, the streaks are often not completely removed. Data from certain coils can also be excluded during reconstruction by visually inspecting the individual coil images, but this is impractical for routine use. In this work, a postprocessing method is proposed to automatically identify those coils whose images contain high levels of streaking for subsequent exclusion during reconstruction. The proposed method was demonstrated in vivo dynamic contrast enhanced MRI datasets acquired using a three-dimensional hybrid radial sequence. The results demonstrate that the proposed strategy substantially improves the image quality and show excellent agreement with images reconstructed with manually determined coil selection. PMID:21656562

  12. Streak artifact reduction in cardiac cone beam CT

    NASA Astrophysics Data System (ADS)

    Shechter, Gilad; Naveh, Galit; Lessick, Jonathan; Altman, Ami

    2005-04-01

    Cone beam reconstructed cardiac CT images suffer from characteristic streak artifacts that affect the quality of coronary artery imaging. These artifacts arise from inhomogeneous distribution of noise. While in non-tagged reconstruction inhomogeneity of noise distribution is mainly due to anisotropy of the attenuation of the scanned object (e.g. shoulders), in cardiac imaging it is largely influenced by the non-uniform distribution of the acquired data used for reconstructing the heart at a given phase. We use a cardiac adaptive filter to reduce these streaks. In difference to previous methods of adaptive filtering that locally smooth data points on the basis of their attenuation values, our filter is applied as a function of the noise distribution of the data as it is used in the phase selective reconstruction. We have reconstructed trans-axial images without adaptive filtering, with a regular adaptive filter and with the cardiac adaptive filter. With the cardiac adaptive filter significant reduction of streaks is achieved, and thus image quality is improved. The coronary vessel is much more pronounced in the cardiac adaptive filtered images, in slab MIP the main coronary artery branches are more visible, and non-calcified plaque is better differentiated from vessel wall. This improvement is accomplished without altering significantly the border definition of calcified plaques.

  13. Angioid streaks - a rare cause of neovascular glaucoma. Case report.

    PubMed Central

    Ungureanu, E; Geamanu, A; Careba, I; Grecescu, M; Gradinaru, S

    2014-01-01

    Rationale. Neovascular glaucoma is the type of glaucoma most refractory to treatment. The most frequent causes are those associated with retinal hypoxia, such as proliferative diabetic retinopathy, central retinal vein occlusion, branch retinal vein occlusion, central retinal arterial occlusion, ischemic ocular syndrome etc. Rare causes of neovascular glaucoma are multiple and are due to VEGF synthesis associated with chorioretinal inflammations or degenerations. We present a case with neovascular glaucoma associated with an extremely rare cause, angioid streaks Objective. The objective of our prsentation was to asses efficacy of the 5-FU associated trabeculectomy following bevacizumab intravitreal administration Methods and results. Case report of a 48 years old female patient which presented at the emergency room with painful red left eye. At presentation best corrected left eye visual acuity was 1/10, intraocular pressure was 36 mm Hg. Examination established the diagnosis of Neovascular glaucoma associated with angioid streaks. After intravenous Manitol, oral Acetazolamide and topical treatment with fixed combination timolol-brinzolamide, topical steroid and mydriatic intraocular pressure decreased. Intravitreal bevacizumab injection was performed, followed after 3 weeks by trabeculectomy. Discussion. Angioid streaks are an extremely rare cause of neovascular glaucoma. The treatment is similar to the treatment for other causes of neovascular glaucoma PMID:27057253

  14. Infrared imagery of streak formation in a breaking wave

    NASA Astrophysics Data System (ADS)

    Handler, Robert A.; Savelyev, Ivan; Lindsey, Michael

    2012-12-01

    High resolution infrared imagery of breaking waves in a wave-tank free of wind shear or current reveals the production of a "streaky," quasi-periodic thermal pattern produced during the breaking process. The streaks, or elongated patterns of warm and cold fluid, are found to form only when surface turbulence is present before wave breaking occurs. This suggests that wave-turbulence interaction is one mechanism that can lead to streak formation in breaking wave systems. More specifically, the streaky structures observed in these experiments may be caused by an intense, rapid tilting, and stretching of pre-existing vertical vorticity by the Stokes drift generated at or near the breaking wave crests, thereby generating a coherent system of counter-rotating vortices. We attempt to relate our observations to the recent theory of Teixeira and Belcher [J. Fluid Mech. 458, 229-267 (2002), 10.1017/S0022112002007838]. Some properties of the streaks, such as the dependence of their lifetimes and spanwise scale on wave amplitude, are presented.

  15. Design of microcontroller based system for automation of streak camera

    SciTech Connect

    Joshi, M. J.; Upadhyay, J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P.

    2010-08-15

    A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers.

  16. Resolution limitations and optimization of the LLNL streak camera focus

    SciTech Connect

    Lerche, R.A.; Griffith, R.L.

    1987-09-01

    The RCA C73435 image tube is biased at voltages far from its original design in the LLNL ultrafast (10 ps) streak camera. Its output resolution at streak camera operating potentials has been measured as a function of input slit width, incident-light wavelength, and focus-grid voltage. The temporal resolution is insensitive to focus-grid voltage for a narrow (100 ..mu..m) input slit, but is very sensitive to focus-grid voltage for a wide (2 mm) input slit. At the optimum wide-slit focus voltage, temporal resolution is insensitive to slit width. Spatial resolution is nearly independent of focus-grid voltage for values that give good temporal resolution. Both temporal and spatial resolution depend on the incident-light wavelength. Data for 1.06-..mu..m light show significantly better focusing than for 0.53-..mu..m light. Streak camera operation is simulated with a computer program that calculates photoelectron trajectories. Electron ray tracing describes all of the observed effects of slit width, incident-light wavelength, and focus-grid voltage on output resolution. 7 refs.

  17. Slope streaks on Mars: A new “wet” mechanism

    NASA Astrophysics Data System (ADS)

    Kreslavsky, Mikhail A.; Head, James W.

    2009-06-01

    Slope steaks are one of the most intriguing modern phenomena observed on Mars. They have been mostly interpreted as some specific type of granular flow. We propose another mechanism for slope streak formation on Mars. It involves natural seasonal formation of a modest amount of highly concentrated chloride brines within a seasonal thermal skin, and runaway propagation of percolation fronts. Given the current state of knowledge of temperature regimes and the composition and structure of the surface layer in the slope streak regions, this mechanism is consistent with the observational constraints; it requires an assumption that a significant part of the observed chlorine to be in form of calcium and ferric chloride, and a small part of the observed hydrogen to be in form of water ice. This "wet" mechanism has a number of appealing advantages in comparison to the widely accepted "dry" granular flow mechanism. Potential tests for the "wet" mechanism include better modeling of the temperature regime and observations of the seasonality of streak formation.

  18. Design of microcontroller based system for automation of streak camera

    NASA Astrophysics Data System (ADS)

    Joshi, M. J.; Upadhyay, J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P.

    2010-08-01

    A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers.

  19. Stabilization of boundary layer streaks by plasma actuators

    NASA Astrophysics Data System (ADS)

    Riherd, Mark; Roy, Subrata

    2014-03-01

    A flow's transition from laminar to turbulent leads to increased levels of skin friction. In recent years, dielectric barrier discharge actuators have been shown to be able to delay the onset of turbulence in boundary layers. While the laminar to turbulent transition process can be initiated by several different instability mechanisms, so far, only stabilization of the Tollmien-Schlichting path to transition has received significant attention, leaving the stabilization of other transition paths using these actuators less explored. To fill that void, a bi-global stability analysis is used here to examine the stabilization of boundary layer streaks in a laminar boundary layer. These streaks, which are important to both transient and by-pass instability mechanisms, are damped by the addition of a flow-wise oriented plasma body force to the boundary layer. Depending on the magnitude of the plasma actuation, this damping can be up to 25% of the perturbation's kinetic energy. The damping mechanism appears to be due to highly localized effects in the immediate vicinity of the body force, and when examined using a linearized Reynolds-averaged Navier-Stokes energy balance, indicate negative production of the perturbation's kinetic energy. Parametric studies of the stabilization have also been performed, varying the magnitude of the plasma actuator's body force and the spanwise wavenumber of the actuation. Based on these parametric studies, the damping of the boundary layer streaks appears to be linear with respect to the total amount of body force applied to the flow.

  20. Analysis of extraembryonic mesodermal structure formation in the absence of morphological primitive streak.

    PubMed

    Jin, Jiu-Zhen; Zhu, Yuanqi; Warner, Dennis; Ding, Jixiang

    2016-08-01

    During mouse gastrulation, the primitive streak is formed on the posterior side of the embryo. Cells migrate out of the primitive streak to form the future mesoderm and endoderm. Fate mapping studies revealed a group of cell migrate through the proximal end of the primitive streak and give rise to the extraembryonic mesoderm tissues such as the yolk sac blood islands and allantois. However, it is not clear whether the formation of a morphological primitive streak is required for the development of these extraembryonic mesodermal tissues. Loss of the Cripto gene in mice dramatically reduces, but does not completely abolish, Nodal activity leading to the absence of a morphological primitive streak. However, embryonic erythrocytes are still formed and assembled into the blood islands. In addition, Cripto mutant embryos form allantoic buds. However, Drap1 mutant embryos have excessive Nodal activity in the epiblast cells before gastrulation and form an expanded primitive streak, but no yolk sac blood islands or allantoic bud formation. Lefty2 embryos also have elevated levels of Nodal activity in the primitive streak during gastrulation, and undergo normal blood island and allantois formation. We therefore speculate that low level of Nodal activity disrupts the formation of morphological primitive streak on the posterior side, but still allows the formation of primitive streak cells on the proximal side, which give rise to the extraembryonic mesodermal tissues formation. Excessive Nodal activity in the epiblast at pre-gastrulation stage, but not in the primitive streak cells during gastrulation, disrupts extraembryonic mesoderm development. PMID:27273137

  1. Response of maize (Zea mays L.) lines carrying Wsm1, Wsm2 and Wsm3 to the potyviruses Johnsongrass mosaic virus and Sorghum mosaic virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize dwarf mosaic disease is one of the most important viral diseases of maize throughout the world. It is caused by a set of related viruses in the family Potyviridae, genus Potyvirus, including Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), Johnsongrass mosaic virus (JGMV), and S...

  2. Maize (Zea mays L.).

    PubMed

    Frame, Bronwyn; Warnberg, Katey; Main, Marcy; Wang, Kan

    2015-01-01

    Agrobacterium tumefaciens-mediated transformation is an effective method for introducing genes into maize. In this chapter, we describe a detailed protocol for genetic transformation of the maize genotype Hi II. Our starting plant material is immature embryos cocultivated with an Agrobacterium strain carrying a standard binary vector. In addition to step-by-step laboratory transformation procedures, we include extensive details in growing donor plants and caring for transgenic plants in the greenhouse. PMID:25300834

  3. On the nature and visibility of crater-associated streaks on Mars

    NASA Technical Reports Server (NTRS)

    Veverka, J.; Thomas, P.; Sagan, C.

    1978-01-01

    The paper considers Mariner 9 and Viking data that contradict Kuzmin's (1975) hypothesis that all crater-associated wind streaks on Mars are depositional and consist of unresolved barchan-like dunes. According to Kuzmin's hypothesis, any streak can appear either bright or dark relative to its surroundings depending on the sun's position. The spacecraft images, however, show examples of dark and light streaks visible at the same azimuth angle of the sun. Evidence that bright and dark streaks differ both in morphology and in character is considered. It is suggested that the common ragged dark streaks are probably erosion scars while most bright streaks probably represent accumulations of bright dust-storm fallout.

  4. Hot streaks and phantom cooling in a turbine rotor passage. II - Combined effects and analytical modelling

    NASA Technical Reports Server (NTRS)

    Roback, Richard J.; Dring, Robert P.

    1992-01-01

    Experimental documentation and analytical correlations demonstrating the effects of hot streak accumulation and phantom cooling on turbine rotor airfoil surface temperature are presented. Results are shown which quantify the impact of a nonuniform temperature profile at the entrance of a turbine due to combustor-generated hot and cold streaks, and cooling air discharged from the trailing edge of the upstream stator. Experimental results are shown for a range of controlling variables to identify where streak accumulation and phantom cooling were most likely to be strongest. These variables include streak-to-free stream density ratio, streak injection location, and coolant-to-free stream density and velocity ratios. Experimental results are shown for the combined effects of hot streak and stator coolant on the adiabatic recovery temperature of the rotor.

  5. Effects of the Fusarium verticillioides mycotoxin, fumonisin B1, on maize stomatal behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium verticillioides is a non-obligate plant pathogen causing a number of maize diseases and is responsible for the production of fumonisin B1 (FB1), a potential human carcinogen and agent of fatal farm animal diseases. The effect of FB1 on the health and development of maize seedlings was recen...

  6. Global Maize Trade and Food Security: Implications from a Social Network Model

    PubMed Central

    Wu, Felicia; Guclu, Hasan

    2013-01-01

    In this study, we developed a social network model of the global trade of maize: one of the most important food, feed, and industrial crops worldwide, and critical to food security. We used this model to analyze patterns of maize trade among nations, and to determine where vulnerabilities in food security might arise if maize availability were decreased due to factors such as diversion to non-food uses, climatic factors, or plant diseases. Using data on imports and exports from the United Nations Commodity Trade Statistics Database for each year from 2000 to 2009 inclusive, we summarized statistics on volumes of maize trade between pairs of nations for 217 nations. There is evidence of market segregation among clusters of nations; with three prominent clusters representing Europe, Brazil and Argentina, and the United States. The United States is by far the largest exporter of maize worldwide, while Japan and the Republic of Korea are the largest maize importers. In particular, the star-shaped cluster of the network that represents US maize trade to other nations indicates the potential for food security risks because of the lack of trade these other nations conduct with other maize exporters. If a scenario arose in which US maize could not be exported in as large quantities, maize supplies in many nations could be jeopardized. We discuss this in the context of recent maize ethanol production and its attendant impacts on food prices elsewhere worldwide. PMID:23656551

  7. Global maize trade and food security: implications from a social network model.

    PubMed

    Wu, Felicia; Guclu, Hasan

    2013-12-01

    In this study, we developed a social network model of the global trade of maize: one of the most important food, feed, and industrial crops worldwide, and critical to food security. We used this model to analyze patterns of maize trade among nations, and to determine where vulnerabilities in food security might arise if maize availability was decreased due to factors such as diversion to nonfood uses, climatic factors, or plant diseases. Using data on imports and exports from the U.N. Commodity Trade Statistics Database for each year from 2000 to 2009 inclusive, we summarized statistics on volumes of maize trade between pairs of nations for 217 nations. There is evidence of market segregation among clusters of nations; with three prominent clusters representing Europe, Brazil and Argentina, and the United States. The United States is by far the largest exporter of maize worldwide, whereas Japan and the Republic of Korea are the largest maize importers. In particular, the star-shaped cluster of the network that represents U.S. maize trade to other nations indicates the potential for food security risks because of the lack of trade these other nations conduct with other maize exporters. If a scenario arose in which U.S. maize could not be exported in as large quantities, maize supplies in many nations could be jeopardized. We discuss this in the context of recent maize ethanol production and its attendant impacts on food prices elsewhere worldwide. PMID:23656551

  8. Surface properties of the Pettit wind streak on Mars Implications for sediment transport

    NASA Astrophysics Data System (ADS)

    Zimbelman, J. R.

    1986-04-01

    Satellite imagery of the Pettit streak on Amazonis Planitia are discussed in terms of the details of wind streaks and their associated sediments. Increasingly more detailed blow-ups of the available imagery demonstrate that the Pettit streak holds both a Type I bright streak (at the crater rim) and a Type II dark streak beginning at the dark patch within the crater. The lowest albedos measured, 0.20-0.22, are associated with the highest thermal inertia, indicative of grain diameters similar to medium sand, i.e., ranging from 250-350 microns. The brightest portions of the streak have albedos over 0.26 and a low thermal inertia, in the range 3-4, which implies the presence of fine-grained sand, diameters from 50-100 microns. The particle grains are less than 50 microns diameter in the surrounding plains, which have an approximately uniform albedo (0.27) and a thermal inertia of 2.5, characteristics typical of silt or clay. Current streak models describe the dark streak well, but do not account for the bright streak, which may be optically thick patches of very fine dust.

  9. Defrosting Polar Dunes--Dark Spots and Wind Streaks

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The first time that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)team saw dark spots on defrosting dune surfaces was in August and September of 1998. At that time, it was the north polar seasonal frost cap that was subliming away (more recent images from 1999 have shown the south polar frosts). This picture (above) shows a small portion of the giant dune field that surrounds the north polar region, as it appeared on August 23, 1998. At the time, it was early northern spring and the dunes were still covered with winter frost.

    Dark spots had appeared on the north polar dunes, and many of them exhibited a radial or semi-radial pattern of dark streaks and streamers. At first, there was speculation that the streaks indicated that the defrosting process might somehow involve explosions! The dark spots seemed to resemble small craters with dark, radial ejecta. It seemed possible that frozen carbon dioxide trapped beneath water ice might somehow heat up, turn to gas, expand, and then 'explode' in either a small blast or at least a 'puff' of air similar to that which comes from the blowhole of a surfacing whale or seal.

    The image shown here changed the earlier impression. The dark spots and streaks do not result from explosions. The spots--though not well understood--represent the earliest stages of defrosting on the sand dunes. The streaks, instead of being caused by small explosions, are instead the result of wind. In this picture, the fine, dark streaks show essentially identical orientations from spot to spot (e.g., compare the spots seen in boxes (a) and (b)). Each ray of dark material must result from wind blowing from a particular direction--for example, all of the spots in this picture exhibit a ray that points toward the upper left corner of the image, and each of these rays indicates the same wind regime. Each spot also has a ray pointing toward the lower right and top/upper-right. These, too, must indicate periods when the wind was strong

  10. Streaked radiography measurements of convergent ablator performance (invited)

    SciTech Connect

    Hicks, D. G.; Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.

    2010-10-15

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other ablator rocket parameters have been measured using a single streaked x-ray radiograph. A regularization technique has been used to determine the ablator density profile {rho}(r) at each time step; moments of {rho}(r) then provide the areal density, average radius, and mass of the unablated, or remaining, ablator material, with the velocity determined from the time derivative of the average radius. The technique has been implemented on experiments at the OMEGA laser facility.

  11. Maize Photoperiod Control: Part II

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the 2007 and 2008 seasons, the staff of the Germplasm Enhancement of Maize Project and the Maize Curatorial Project staff of the North Central Regional Plant Introduction Station experimented with various types of structures to ensure that field plantings of tropical maize germplasm were expo...

  12. Simultaneous detection and differentiation of Rice black streaked dwarf virus (RBSDV) and Southern rice black streaked dwarf virus (SRBSDV) by duplex real time RT-PCR

    PubMed Central

    2013-01-01

    Background The diseases caused by Rice black streaked dwarf virus (RBSDV) and Southern rice black streaked dwarf virus (SRBSDV) have been occurring epidemically in China and southeastern Asia in recent years. A sensitive, reliable and quantitative method is required to detect and distinguish for RBSDV and SRBSDV in rice and vector insects. Results We developed a sensitive and lineage-specific duplex real time RT-qPCR for detection of RBSDV and SRBSDV in a single or/and double infection in rice samples. The duplex RT-qPCR was optimized using standard samples transcribed by T7 Large Scale RNA Production System in vitro. We developed a reliable system for duplex RT-qPCR, in which its co-efficiency of RBSDV and SRBSDV, were 91.6% and 90.7%, respectively. The coefficient of determination was more than 0.990; the slope of linear equation was −3.542, and −3.567, respectively. Out of 30 samples collected in North and Central China, which were suspected to be infected with these two viruses, 10 samples were detected RBSDV positive by RT-PCR and 12 samples by RT-qPCR. No mixed infections were found. Simultaneously, out of total 60 samples collected from Southern China, which were also suspected to be infected with these two viruses, 41 samples were determined SRBSDV positive by RT-PCR and 47 samples by RT-qPCR. Also in this case no mixed infections were found. The rice genes eEF-1a and UBQ5 were selected as internal controls for quantification assay also performed as good expression stability. Conclusion The duplex RT-qPCR assay provided as a sufficiently sensitive, specific, accurate, reproducible and rapid tool for the detection and differentiation of RBSDV and SRBSDV. The RT-qPCR assay can be used in routine diagnostic of these two viruses in order to study the disease epidemiology in rice crops. PMID:23331990

  13. Microprocessor-controlled, wide-range streak camera

    SciTech Connect

    Amy E. Lewis, Craig Hollabaugh

    2006-09-01

    Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera’s user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.

  14. Range accuracy analysis of streak tube imaging lidar systems

    NASA Astrophysics Data System (ADS)

    Ye, Guangchao; Fan, Rongwei; Chen, Zhaodong; Yuan, Wei; Chen, Deying; He, Ping

    2016-02-01

    Streak tube imaging lidar (STIL) is an active imaging system that has a high range accuracy and a wide range gate with the use of a pulsed laser transmitter and streak tube receiver to produce 3D range images. This work investigates the range accuracy performance of STIL systems based on a peak detection algorithm, taking into account the effects of blurring of the image. A theoretical model of the time-resolved signal distribution, including the static blurring width in addition to the laser pulse width, is presented, resulting in a modified range accuracy analysis. The model indicates that the static blurring width has a significant effect on the range accuracy, which is validated by both the simulation and experimental results. By using the optimal static blurring width, the range accuracies are enhanced in both indoor and outdoor experiments, with a stand-off distance of 10 m and 1700 m, respectively, and corresponding, best range errors of 0.06 m and 0.25 m were achieved in a daylight environment.

  15. [Further development of a streak retinoscope with calibrated collimator].

    PubMed

    Rohrschneider, K; Koch, H R

    1992-08-01

    Development and rationale of a new streak retinoscope have been discussed in an earlier paper. In contrast to classical retinoscopy this retinoscope determines the refraction by forming the narrowest streak in the test person's pupil with a calibrated collimator. In addition to the first prototype the extension of the lamp according to variation of the refraction is measured electronically and the data are transposed into a computer. This allows to freely choose a working distance in a range from about 30 to 120 cm and therefore it is possible to examine restless patients. Accuracy of the measurement was less than or equal to 0.25 D for Ametropia from -0.5 to 5.0 D in a working distance of 30 cm or from -4.0 to -1.5 D in 100 cm. In most persons it is not necessary to use additional glasses during refraction by choosing the adequate distance. Therefore this method can help to refract kids and other persons which could not be refracted by use of glasses. In addition this method excludes the accommodation of the patient as apposed to regular refractometers. PMID:1434382

  16. THEMIS-IR Emissivity Spectrum of a Large "Dark Streak" near Olympus Mons

    NASA Astrophysics Data System (ADS)

    Brumby, S. P.

    2004-03-01

    "Dark streaks" are unusual transient surface features found on Mars. We have obtained an infrared emissivity spectrum of a large dark streak on the north western edge of Olympus Mons, using imagery from the THEMIS instrument on the Mars Odyssey 2001 spacecraft.

  17. X-ray streak camera diagnostics of picosecond laser-plasma interactions

    SciTech Connect

    Cobble, J.A.; Fulton, R.D.; Jones, L.A.; Kyrala, G.A.; Schappert, G.T.; Taylor, A.J.; Wahlin, E.K.

    1992-05-01

    An x-ray streak camera is used to diagnose a laser-produced Al plasma with time resolution of {approximately}10 ps. A streak record of filtered emission and a time-integrated transmission grating spectrum reveal that the plasma radiation is dominated by emission from He- and H-like resonance lines. 11 refs.

  18. X-ray streak camera diagnostics of picosecond laser-plasma interactions

    SciTech Connect

    Cobble, J.A.; Fulton, R.D.; Jones, L.A.; Kyrala, G.A.; Schappert, G.T.; Taylor, A.J.; Wahlin, E.K.

    1992-01-01

    An x-ray streak camera is used to diagnose a laser-produced Al plasma with time resolution of {approximately}10 ps. A streak record of filtered emission and a time-integrated transmission grating spectrum reveal that the plasma radiation is dominated by emission from He- and H-like resonance lines. 11 refs.

  19. Averaging picosecond streak camera for time resolved x-ray and XUV spectroscopy of ultrashort plasmas

    NASA Astrophysics Data System (ADS)

    Maksimchuk, A.; Nantel, M.; Workman, J.; Umstadter, D.; Mourou, G.; Pikuz, S.

    1996-11-01

    We have developed an averaging picosecond x-ray streak camera that uses a DC-biased semi-insulating GaAs photoconductive switch as a generator of a high-voltage ramp for the deflection plates of the streak camera. The streak camera is operated at a sweep speed of up to 8 ps/mm, with a shot-to-shot jitter of 1 ps. The streak camera driven by this switch is absolutely synhronized with the femtosecond laser pulse and allows the direct accumulation of the x-ray temporal signals at a 10 Hz repetition rate. The streak camera has been used for the investigation of temporal behavior of keV x-ray lines and spectrally resolved XUV emission from solid target at the laser intensity of 10^17 W/cm^2. This work is supported by NSF under Grant STC PHY 8920108.

  20. Satellite Observations of Plume-like Streaks in a Cloud Field in Canada

    NASA Astrophysics Data System (ADS)

    Grasso, Lewis; Lindsey, Daniel T.; Seaman, Curtis J.; Stocks, Brian; Rabin, Robert M.

    2015-04-01

    On the afternoon of 28 October 2013, plume-like streaks were detected by geostationary and polar orbiting satellites over eastern Ontario, Canada. These streaks were characterized by enhanced reflectivity in the visible bands and warmer brightness temperatures at 3.9 µm. These streaks were part of a low-level liquid water cloud layer. Due to the similarity of the streaks to plume-like features in marine stratocumulus caused by smoke from the stacks of ships, so-called ship tracks, a local source of emitted aerosols was suspected and subsequently identified as the burning of logging residue. This event provides further support for the ability of locally enhanced aerosol loading to alter microphysical characteristics of clouds. Ship tracks, pollution plumes from industrial burning, and pyro-cumulus are known examples of this type of interaction. In addition, the plume-like streaks could be used indirectly to identify the location of the source of the emitted particles.

  1. Sub-picosecond streak camera measurements at LLNL: From IR to x-rays

    SciTech Connect

    Kuba, J; Shepherd, R; Booth, R; Steward, R; Lee, E W; Cross, R R; Springer, P T

    2003-12-21

    An ultra fast, sub-picosecond resolution streak camera has been recently developed at the LLNL. The camera is a versatile instrument with a wide operating wavelength range. The temporal resolution of up to 300 fs can be achieved, with routine operation at 500 fs. The streak camera has been operated in a wide wavelength range from IR to x-rays up to 2 keV. In this paper we briefly review the main design features that result in the unique properties of the streak camera and present its several scientific applications: (1) Streak camera characterization using a Michelson interferometer in visible range, (2) temporally resolved study of a transient x-ray laser at 14.7 nm, which enabled us to vary the x-ray laser pulse duration from {approx}2-6 ps by changing the pump laser parameters, and (3) an example of a time-resolved spectroscopy experiment with the streak camera.

  2. Betting Decision Under Break-Streak Pattern: Evidence from Casino Gaming.

    PubMed

    Fong, Lawrence Hoc Nang; So, Amy Siu Ian; Law, Rob

    2016-03-01

    Cognitive bias is prevalent among gamblers, especially those with gambling problems. Grounded in the heuristics theories, this study contributes to the literature by examining a cognitive bias triggered by the break streak pattern in the casino setting. We postulate that gamblers tend to bet on the latest outcome when there is a break-streak pattern. Moreover, three determinants of the betting decision under break-streak pattern, including the streak length of the alternative outcome, the frequency of the latest outcome, and gender, were identified and examined in this study. A non-participatory observational study was conducted among the Cussec gamblers in a casino in Macao. An analysis of 1229 bets confirms our postulation, particularly when the streak of the alternative outcome is long, the latest outcome is frequent, and the gamblers are females. The findings provide meaningful implications for casino management and public policymakers regarding the minimization of gambling harm. PMID:25967106

  3. Characterization of X-ray streak cameras for use on Nova

    SciTech Connect

    Kalantar, D.H.; Bell, P.M.; Costa, R.L.; Hammel, B.A.; Landen, O.L.; Orzechowski, T.J.; Hares, J.D.; Dymoke-Bradshaw, A.K.L.

    1996-09-01

    There are many different types of measurements that require a continuous time history of x-ray emission that can be provided with an x-ray streak camera. In order to properly analyze the images that are recorded with the x-ray streak cameras operated on Nova, it is important to account for the streak characterization of each camera. We have performed a number of calibrations of the streak cameras both on the bench as well as with Nova disk target shots where we use a time modulated laser intensity profile (self-beating of the laser) on the target to generate an x-ray comb. We have measured the streak camera sweep direction and spatial offset, curvature of the electron optics, sweep rate, and magnification and resolution of the electron optics.

  4. Characterization of X-ray streak cameras for use on Nova

    SciTech Connect

    Kalantar, D.H.; Bell, P.M.; Costa, R.L.; Hammel, B.A.; Landen, O.L.; Orzechowski, T.J.; Hares, J.D.; Dymoke-Bradshaw, A.K.L.

    1996-10-01

    There are many different types of measurements that require a continuous time history of x-ray emission that can be provided with an x-ray streak camera. In order to properly analyze the images that are recorded with the x-ray streak cameras operated on Nova, it is important to account for the streak characterization of each camera. We have performed a number of calibrations of the streak cameras both on the bench as well as with Nova disk target shots where we use a time modulated laser intensity profile (self-beating of the laser) an the target to generate an x-ray comb. We have measured the streak camera sweep direction and spatial offset, curvature of the electron optics, sweep rate, and magnification and resolution of the electron optics.

  5. MaizeGDB Community Curation Tools

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB (http://www.maizegdb.org) is the community database for maize genetics and genomics. The success of the MaizeGDB project largely can be attributed to the involvement of the community of maize geneticists. Members of the community have (1) made their data available by contributing to MaizeGD...

  6. MaizeGDB - Past, present, and future

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Maize Genetics and Genomics Database (MaizeGDB) turns 20 this year. This editorial outlines MaizeGDB's history and connection to the Maize Genetics Cooperation, describes key components of how the MaizeGDB interface will be completely redesigned over the course of the next two years to meet cur...

  7. Use of an Advanced Intercross Line Population for Precise Mapping of Quantitative Trait Loci for Gray Leaf Spot Resistance in Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grey leaf spot (GLS) (caused by Cercospora zeae-maydis) of maize (Zea mays L.)is an important fungal disease of maize in the U.S. and worldwide. The IBM population, an advanced intercross recombinant inbred line population derived from a cross between the maize lines Mo17 (resistant) and B73 (sus...

  8. On the convectively unstable nature of optimal streaks in boundary layers

    NASA Astrophysics Data System (ADS)

    Brandt, Luca; Cossu, Carlo; Chomaz, Jean-Marc; Huerre, Patrick; Henningson, Dan S.

    2003-06-01

    The objective of the study is to determine the absolute/convective nature of the secondary instability experienced by finite-amplitude streaks in the flat-plate boundary layer. A family of parallel streaky base flows is defined by extracting velocity profiles from direct numerical simulations of nonlinearly saturated optimal streaks. The computed impulse response of the streaky base flows is then determined as a function of streak amplitude and streamwise station. Both the temporal and spatio-temporal instability properties are directly retrieved from the impulse response wave packet, without solving the dispersion relation or applying the pinching point criterion in the complex wavenumber plane. The instability of optimal streaks is found to be unambiguously convective for all streak amplitudes and streamwise stations. It is more convective than the Blasius boundary layer in the absence of streaks; the trailing edge-velocity of a Tollmien Schlichting wave packet in the Blasius boundary layer is around 35% of the free-stream velocity, while that of the wave packet riding on the streaky base flow is around 70%. This is because the streak instability is primarily induced by the spanwise shear and the associated Reynolds stress production term is located further away from the wall, in a larger velocity region, than for the Tollmien Schlichting instability. The streak impulse response consists of the sinuous mode of instability triggered by the spanwise wake-like profile, as confirmed by comparing the numerical results with the absolute/convective instability properties of the family of two-dimensional wakes introduced by Monkewitz (1988). The convective nature of the secondary streak instability implies that the type of bypass transition studied here involves streaks that behave as amplifiers of external noise.

  9. Quality Protein Maize for Africa: Closing the Protein Inadequacy Gap in Vulnerable Populations12

    PubMed Central

    Nuss, Emily T.; Tanumihardjo, Sherry A.

    2011-01-01

    Africa shares a unique relationship with maize (Zea mays). After its introduction from New World explorers, maize was quickly adopted as the cornerstone of local cuisine, especially in sub-Saharan countries. Although maize provides macro- and micronutrients required for humans, it lacks adequate amounts of the essential amino acids lysine and tryptophan. For those consuming >50% of their daily energy from maize, pandemic protein malnutrition may exist. Severe protein and energy malnutrition increases susceptibility to life-threatening diseases such as tuberculosis and gastroenteritis. A nutritionally superior maize cultivar named quality protein maize (QPM) represents nearly one-half century of research dedicated to malnutrition eradication. Compared with traditional maize types, QPM has twice the amount of lysine and tryptophan, as well as protein bioavailability that rivals milk casein. Animal and human studies suggest that substituting QPM for common maize results in improved health. However, QPM’s practical contribution to maize-subsisting populations remains unresolved. Herein, total protein and essential amino acid requirements recommended by the WHO and the Institute of Medicine were applied to estimate QPM target intake levels for young children and adults, and these were compared with mean daily maize intakes by African country. The comparisons revealed that ∼100 g QPM is required for children to maintain adequacy of lysine, the most limiting amino acid, and nearly 500 g is required for adults. This represents a 40% reduction in maize intake relative to common maize to meet protein requirements. The importance of maize in Africa underlines the potential for QPM to assist in closing the protein inadequacy gap. PMID:22332054

  10. Fusarium graminearum: an pathogen of maize in Nepal, pathogenic variability and mycotoxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium graminearum is an important pathogen of maize in hills of Nepal. It predominantly occurs on maize grown in cool and humid environment of high hills. The pathogen is also known to infect other cereal crops including wheat and rice causing important diseases. The incidence of ear rot is hi...

  11. Nitric oxide detoxification by Fusarium verticillioides flavohemoglobin and role in pathogenicity of maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium verticillioides is a non-obligate plant pathogen of maize causing a number of specific diseases, including root rot, kernel rot, seed rot, stalk rot, and seedling blight. The saprophytic nature of this fungus, its production of the mycotoxin fumonisin, and complex relationship maize puts t...

  12. Diallel analysis of resistance to fusarium ear rot and fumonisin contamination in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Fusarium verticillioides infects maize ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with the mycotoxin fumonisin. Typical hybrid maize breeding programs involve selection for both favorable inbred and hybrid performance, and the...

  13. Maize terpenoid phytoalexins function in resistance against both abiotic and biotic stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize (Zea mays) crop production, which is an essential part of the world’s grain supply, is limited by insect pests, pathogen diseases, and unfavorable weather, such as drought. Zealexins and kauralexins belong to recently identified families of terpenoid phytoalexins that function in maize defense...

  14. In planta reduction of maize seedling stalk lesions by the bacterial endophyte Bacillus mojavensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to autoinfection and alloinfection, maize is susceptible to infection by Fusarium verticillioides resulting in diseases and contamination of maize kernels with the fumonisin mycotoxins. Attempts at controlling this fungus are currently being done with biocontrol agents such as bacteria and this...

  15. Betaine deficiency in maize

    SciTech Connect

    Lerma, C. ); Rich, P.J.; Ju, G.C.; Yang, Wenju; Rhodes, D. ); Hanson, A.D. )

    1991-04-01

    Maize (Zea mays L.) is a betaine-accumulating species, but certain maize genotypes lack betaine almost completely; a single recessive gene has been implicated as the cause of this deficiency. This study was undertaken to determine whether betaine deficiency in diverse maize germplasm is conditioned by the same genetic locus, and to define the biochemical lesion(s) involved. Complementation tests indicated that all 13 deficient genotypes tested shared a common locus. One maize population (P77) was found to be segregating for betaine deficiency, and true breeding individuals were used to produce related lines with and without betaine. Leaf tissue of both betaine-positive and betaine-deficient lines readily converted supplied betaine aldehyde to betaine, but only the betaine-containing line was able to oxidize supplied choline to betaine. This locates the lesion in betaine-deficient plants at the choline {r arrow} betaine aldehyde step of betaine synthesis. Consistent with this location, betaine-deficient plants were shown to have no detectable endogenous pool of betaine aldehyde.

  16. (Genomic variation in maize)

    SciTech Connect

    Rivin, C.J.

    1991-01-01

    These studies have sought to learn how different DNA sequences and sequence arrangements contribute to genome plasticity in maize. We describe quantitative variation among maize inbred lines for tandemly arrayed and dispersed repeated DNA sequences and gene families, and qualitative variation for sequences homologous to the Mutator family of transposons. The potential of these sequences to undergo unequal crossing over, non-allelic (ectopic) recombination and transposition makes them a source of genome instability. We have found examples of rapid genomic change involving these sequences in Fl hybrids, tissue culture cells and regenerated plants. We describe the repetitive portion of the maize genome as composed primarily of sequences that vary markedly in copy number among different genetic stocks. The most highly variable is the 185 bp repeat associated with the heterochromatic chromosome knobs. Even in lines without visible knobs, there is a considerable quantity of tandemly arrayed repeats. We also found a high degree of variability for the tandemly arrayed 5S and ribosomal DNA repeats. While such variation might be expected as the result of unequal cross-over, we were surprised to find considerable variation among lower copy number, dispersed repeats as well. One highly repeated sequence that showed a complex tandem and dispersed arrangement stood out as showing no detectable variability among the maize lines. In striking contrast to the variability seen between the inbred stocks, individuals within a stock were indistinguishable with regard to their repeated sequence multiplicities.

  17. High-speed TV cameras for streak tube readout

    SciTech Connect

    Yates, G.J.; Gallegos, R.A.; Holmes, V.H. ); Turko, B.T. )

    1991-01-01

    Two fast framing TV cameras have been characterized and compared as readout media for imaging of 40 mm diameter streak tube (P-11) phosphor screens. One camera is based upon a Focus-Projection-Scan (FPS) high-speed electrostatic deflected vidicon with 30-mm-diameter PbO target. The other uses an interline transfer charge-coupled device (CCD) with 8.8 {times} 11.4 mm rectangular Si target. The field-of-view (FOV), resolution, responsivity, and dynamic range provided by both cameras when exposed to short duration ({approx} 10 {mu} full width at half maximum (FWHM)) transient illumination followed by a single field readout period of {lt}3 ms are presented. 11 refs., 8 figs., 3 tabs.

  18. Interference effects in angular streaking with a rotating terahertz field

    NASA Astrophysics Data System (ADS)

    Kazansky, A. K.; Bozhevolnov, A. V.; Sazhina, I. P.; Kabachnik, N. M.

    2016-01-01

    A method of angular streaking with a rotating terahertz electric field for photoelectrons produced by femtosecond extreme ultraviolet pulses is suggested and theoretically analyzed. The method can be used for free electron laser (FEL) pulse characterization on a shot-to-shot basis. It is shown that in related measurements an interesting phenomenon appears: formation of very bright and sharp features in the angular resolved electron spectra measured in the plane perpendicular to the collinear beam direction. These features are similar to the conventional caustics in the wave propagation. The caustics are accompanied by a well-developed interference structure. The intensity distribution along the caustic is determined by the envelope of the FEL pulse.

  19. Steering continuum electron dynamics by low-energy attosecond streaking

    NASA Astrophysics Data System (ADS)

    Geng, Ji-Wei; Xiong, Wei-Hao; Xiao, Xiang-Ru; Gong, Qihuang; Peng, Liang-You

    2016-08-01

    A semiclassical model is developed to understand the electronic dynamics in the low-energy attosecond streaking. Under a relatively strong infrared (IR) pulse, the low-energy part of photoelectrons initialized by a single attosecond pulse (SAP) can either rescatter with the ionic core and induce interferences structures in the momentum spectra of the ionized electrons or be recaptured into the Rydberg states. The Coulomb potential plays essential roles in both the electron rescattering and recapturing processes. We find that by changing the time delay between the SAP and the IR pulse, the photoelectrons yield or the population of the Rydberg states can be effectively controlled. The present study demonstrates a fascinating way to steer the electron motion in the continuum.

  20. Cloning and sequence analysis of banana streak virus DNA.

    PubMed

    Harper, G; Hull, R

    1998-01-01

    Banana streak virus (BSV), a member of the Badnavirus group of plant viruses, causes severe problems in banana cultivation, reducing fruit yield and restricting plant breeding and the movement of germplasm. Current detection methods are relatively insensitive. In order to develop a PCR-based diagnostic method that is both reliable and sensitive, the genome of a Nigerian isolate of BSV has been sequenced and shown to comprise 7389 bp and to be organized in a manner characteristic of badnaviruses. Comparison of this sequence with those of other badnaviruses showed that BSV is a distinct virus. PCR with primers based on sequence data indicated that BSV sequences are present in the banana genome. PMID:9926402

  1. StreakDet data processing and analysis pipeline for space debris optical observations

    NASA Astrophysics Data System (ADS)

    Virtanen, Jenni; Flohrer, Tim; Muinonen, Karri; Granvik, Mikael; Torppa, Johanna; Poikonen, Jonne; Lehti, Jussi; Santti, Tero; Komulainen, Tuomo; Naranen, Jyri

    We describe a novel data processing and analysis pipeline for optical observations of space debris. The monitoring of space object populations requires reliable acquisition of observational data, to support the development and validation of space debris environment models, the build-up and maintenance of a catalogue of orbital elements. In addition, data is needed for the assessment of conjunction events and for the support of contingency situations or launches. The currently available, mature image processing algorithms for detection and astrometric reduction of optical data cover objects that cross the sensor field-of-view comparably slowly, and within a rather narrow, predefined range of angular velocities. By applying specific tracking techniques, the objects appear point-like or as short trails in the exposures. However, the general survey scenario is always a “track before detect” problem, resulting in streaks, i.e., object trails of arbitrary lengths, in the images. The scope of the ESA-funded StreakDet (Streak detection and astrometric reduction) project is to investigate solutions for detecting and reducing streaks from optical images, particularly in the low signal-to-noise ratio (SNR) domain, where algorithms are not readily available yet. For long streaks, the challenge is to extract precise position information and related registered epochs with sufficient precision. Although some considerations for low-SNR processing of streak-like features are available in the current image processing and computer vision literature, there is a need to discuss and compare these approaches for space debris analysis, in order to develop and evaluate prototype implementations. In the StreakDet project, we develop algorithms applicable to single images (as compared to consecutive frames of the same field) obtained with any observing scenario, including space-based surveys and both low- and high-altitude populations. The proposed processing pipeline starts from the

  2. Illusory Streaks from Corners and Their Perceptual Integration

    PubMed Central

    Roncato, Sergio; Guidi, Stefano; Parlangeli, Oronzo; Battaglini, Luca

    2016-01-01

    Perceptual grouping appears both as organized forms of real figural units and as illusory or “phantom” figures. The phenomenon is visible in the Hermann grid and in configurations which generate color spreading, e.g., “neon effects.” These configurations, generally regular repetitive patterns, appear to be crossed by illusory bands filled with a brighter shade or a colored tinge connecting the various loci of illusory effects. In this work, we explore a particular new illusion showing a grouping effect. It manifests as illusory streaks irradiating from the vertexes of angular contours and connecting pairs of figures nearby. It is only clearly visible when more than one figure is shown, and takes the shape of a net crossing their corners. Although the grouping effect is vivid, the local source of the illusion is completely hidden. Theories explaining this effect as due to the irradiation of illusory streaks (mainly that of Grossberg and Mingolla, 1985a,b) do not fully explain the figural patterns presented here. Illusory effects have already been documented at the angles of various figures, causing them to alter in amplitude and brightness; however, the figure illustrated here appears to have different features and location. Phenomenological observations and an experiment were conducted to assess the role played by geometric and photometric parameters in this illusion. Results showed that sharp angles, in low contrast with the surround, are the main source of the illusion which, however, only becomes visible when at least two figures are close together. These findings are discussed with respect to theories of contour processing and perceptual grouping, and in relation to other illusions. PMID:27445922

  3. Illusory Streaks from Corners and Their Perceptual Integration.

    PubMed

    Roncato, Sergio; Guidi, Stefano; Parlangeli, Oronzo; Battaglini, Luca

    2016-01-01

    Perceptual grouping appears both as organized forms of real figural units and as illusory or "phantom" figures. The phenomenon is visible in the Hermann grid and in configurations which generate color spreading, e.g., "neon effects." These configurations, generally regular repetitive patterns, appear to be crossed by illusory bands filled with a brighter shade or a colored tinge connecting the various loci of illusory effects. In this work, we explore a particular new illusion showing a grouping effect. It manifests as illusory streaks irradiating from the vertexes of angular contours and connecting pairs of figures nearby. It is only clearly visible when more than one figure is shown, and takes the shape of a net crossing their corners. Although the grouping effect is vivid, the local source of the illusion is completely hidden. Theories explaining this effect as due to the irradiation of illusory streaks (mainly that of Grossberg and Mingolla, 1985a,b) do not fully explain the figural patterns presented here. Illusory effects have already been documented at the angles of various figures, causing them to alter in amplitude and brightness; however, the figure illustrated here appears to have different features and location. Phenomenological observations and an experiment were conducted to assess the role played by geometric and photometric parameters in this illusion. Results showed that sharp angles, in low contrast with the surround, are the main source of the illusion which, however, only becomes visible when at least two figures are close together. These findings are discussed with respect to theories of contour processing and perceptual grouping, and in relation to other illusions. PMID:27445922

  4. Chapter 11 Insect transmitted virus and mollicute disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect-transmitted diseases of maize are found throughout the maize growing regions of the world. These diseases are caused by viruses, phytoplasmas and spiroplasmas. The pathogens, vectors and plant hosts for the major insect-transmitted diseases of maize world-wide are reviewed. Factors leading to...

  5. Comparative analysis of virus-derived small RNAs within cassava (Manihot esculenta Crantz) infected with cassava brown streak viruses.

    PubMed

    Ogwok, Emmanuel; Ilyas, Muhammad; Alicai, Titus; Rey, Marie E C; Taylor, Nigel J

    2016-04-01

    Infection of plant cells by viral pathogens triggers RNA silencing, an innate antiviral defense mechanism. In response to infection, small RNAs (sRNAs) are produced that associate with Argonaute (AGO)-containing silencing complexes which act to inactivate viral genomes by posttranscriptional gene silencing (PTGS). Deep sequencing was used to compare virus-derived small RNAs (vsRNAs) in cassava genotypes NASE 3, TME 204 and 60444 infected with the positive sense single-stranded RNA (+ssRNA) viruses cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), the causal agents of cassava brown streak disease (CBSD). An abundance of 21-24nt vsRNAs was detected and mapped, covering the entire CBSV and UCBSV genomes. The 21nt vsRNAs were most predominant, followed by the 22 nt class with a slight bias toward sense compared to antisense polarity, and a bias for adenine and uracil bases present at the 5'-terminus. Distribution and frequency of vsRNAs differed between cassava genotypes and viral genomes. In susceptible genotypes TME 204 and 60444, CBSV-derived sRNAs were seen in greater abundance than UCBSV-derived sRNAs. NASE 3, known to be resistant to UCBSV, accumulated negligible UCBSV-derived sRNAs but high populations of CBSV-derived sRNAs. Transcript levels of cassava homologues of AGO2, DCL2 and DCL4, which are central to the gene-silencing complex, were found to be differentially regulated in CBSV- and UCBSV-infected plants across genotypes, suggesting these proteins play a role in antiviral defense. Irrespective of genotype or viral pathogen, maximum populations of vsRNAs mapped to the cytoplasmic inclusion, P1 and P3 protein-encoding regions. Our results indicate disparity between CBSV and UCBSV host-virus interaction mechanisms, and provide insight into the role of virus-induced gene silencing as a mechanism of resistance to CBSD. PMID:26811902

  6. Comparing the regional epidemiology of the cassava mosaic and cassava brown streak virus pandemics in Africa.

    PubMed

    Legg, J P; Jeremiah, S C; Obiero, H M; Maruthi, M N; Ndyetabula, I; Okao-Okuja, G; Bouwmeester, H; Bigirimana, S; Tata-Hangy, W; Gashaka, G; Mkamilo, G; Alicai, T; Lava Kumar, P

    2011-08-01

    The rapid geographical expansion of the cassava mosaic disease (CMD) pandemic, caused by cassava mosaic geminiviruses, has devastated cassava crops in 12 countries of East and Central Africa since the late 1980s. Region-level surveys have revealed a continuing pattern of annual spread westward and southward along a contiguous 'front'. More recently, outbreaks of cassava brown streak disease (CBSD) were reported from Uganda and other parts of East Africa that had been hitherto unaffected by the disease. Recent survey data reveal several significant contrasts between the regional epidemiology of these two pandemics: (i) severe CMD radiates out from an initial centre of origin, whilst CBSD seems to be spreading from independent 'hot-spots'; (ii) the severe CMD pandemic has arisen from recombination and synergy between virus species, whilst the CBSD pandemic seems to be a 'new encounter' situation between host and pathogen; (iii) CMD pandemic spread has been tightly linked with the appearance of super-abundant Bemisia tabaci whitefly vector populations, in contrast to CBSD, where outbreaks have occurred 3-12 years after whitefly population increases; (iv) the CMGs causing CMD are transmitted in a persistent manner, whilst the two cassava brown streak viruses appear to be semi-persistently transmitted; and (v) different patterns of symptom expression mean that phytosanitary measures could be implemented easily for CMD but have limited effectiveness, whereas similar measures are difficult to apply for CBSD but are potentially very effective. An important similarity between the pandemics is that the viruses occurring in pandemic-affected areas are also found elsewhere, indicating that contrary to earlier published conclusions, the viruses per se are unlikely to be the key factors driving the two pandemics. A diagrammatic representation illustrates the temporal relationship between B. tabaci abundance and changing incidences of both CMD and CBSD in the Great Lakes region

  7. Dust Devils Seen Streaking Across Mars: PART 1--What Are These?

    NASA Technical Reports Server (NTRS)

    2000-01-01

    PIA02376 [figure removed for brevity, see original site]

    Dark streaks, everywhere! Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of the middle latitudes of the northern and southern hemispheres of Mars show wild patterns of criss-crossing dark streaks. Many of these streaks are straight and narrow, others exhibit curly arcs, twists, and loops. They often cross over hills, run straight across dunes and ripples, and go through fields of house-sized boulders. The two examples shown above were acquired in the last three months. Both pictures are illuminated by sunlight from the upper left. The first picture (left), showing dark streaks on the rippled flats of Argyre Planitia, covers an area 3 km by 5 km (1.9 by 3.1 miles) at a latitude of 51oS. The second picture (right) shows an area approximately 3 km by 5 km in Promethei Terra at a latitude of 58oS.

    For many months the MOC science team was seeing streaks such as these, but were uncertain how they formed. One speculation was that they might result from the passage of dust devils. Each dust devil would leave a dark streak by removing bright dust from the terrain in its path, revealing a darker surface underneath. An image described by the MOC team in July 1998 showed examples of streaks that were, at the time, speculated to be caused by dust devils.

  8. Flat-field response and geometric distortion measurements of optical streak cameras

    SciTech Connect

    Montgomery, D.S.; Drake, R.P.; Jones, B.A.; Wiedwald, J.D.

    1987-08-01

    To accurately measure pulse amplitude, shape, and relative time histories of optical signals with an optical streak camera, it is necessary to correct each recorded image for spatially-dependent gain nonuniformity and geometric distortion. Gain nonuniformities arise from sensitivity variations in the streak-tube photocathode, phosphor screen, image-intensifier tube, and image recording system. These nonuniformities may be severe, and have been observed to be on the order of 100% for some LLNL optical streak cameras. Geometric distortion due to optical couplings, electron-optics, and sweep nonlinearity not only affects pulse position and timing measurements, but affects pulse amplitude and shape measurements as well. By using a 1.053-..mu..m, long-pulse, high-power laser to generate a spatially and temporally uniform source as input to the streak camera, the combined effects of flat-field response and geometric distortion can be measured under the normal dynamic operation of cameras with S-1 photocathodes. Additionally, by using the same laser system to generate a train of short pulses that can be spatially modulated at the input of the streak camera, we can effectively create a two-dimensional grid of equally-spaced pulses. This allows a dynamic measurement of the geometric distortion of the streak camera. We will discuss the techniques involved in performing these calibrations, will present some of the measured results for LLNL optical streak cameras, and will discuss software methods to correct for these effects. 6 refs., 6 figs.

  9. Efficient and stable expression of GFP through Wheat streak mosaic virus-based vectors in cereal hosts using a range of cleavage sites: Formation of dense fluorescent aggregates for sensitive virus tracking

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of Wheat streak mosaic virus (WSMV)-based expression vectors were developed by engineering cycle 3 GFP (GFP) cistron between P1 and HC-Pro cistrons with several catalytic/cleavage peptides at the C-terminus of GFP. WSMV-GFP vectors with the Foot-and-mouth disease virus 1D/2A or 2A catalytic...

  10. A genome-wide association study reveals genes associated with fusarium ear rot resistance in a maize core diversity panel

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium ear rot is a common disease of maize that affects food and feed quality globally. Resistance to the disease is highly quantitative, and maize breeders have difficulty incorporating polygenic resistance alleles from unadapted donor sources into elite breeding populations without having a ne...

  11. Stabilization of the hypersonic boundary layer by finite-amplitude streaks

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Fu, Song; Hanifi, Ardeshir

    2016-02-01

    Stabilization of two-dimensional disturbances in hypersonic boundary layer flows by finite-amplitude streaks is investigated using nonlinear parabolized stability equations. The boundary-layer flows at Mach numbers 4.5 and 6.0 are studied in which both first and second modes are supported. The streaks considered here are driven either by the so-called optimal perturbations (Klebanoff-type) or the centrifugal instability (Görtler-type). When the streak amplitude is in an appropriate range, i.e., large enough to modulate the laminar boundary layer but low enough to not trigger secondary instability, both first and second modes can effectively be suppressed.

  12. Improvements in Off-Center Focusing in an X-ray Streak Camera

    SciTech Connect

    McDonald, J W; Weber, F; Holder, J P; Bell, P M

    2003-07-17

    Due to the planar construction of present x-ray streak tubes significant off-center defocusing is observed in both static and dynamic images taken with one-dimensional resolution slits. Based on the streak tube geometry curved photocathodes with radii of curvature ranging from 3.5 to 18 inches have been fabricated. We report initial off-center focusing performance data on the evaluation of these ''improved'' photocathodes in an X-ray streak camera and an update on the theoretical simulations to predict the optimum cathode curvature.

  13. Ultra Fast X-ray Streak Camera for TIM Based Platforms

    SciTech Connect

    Marley, E; Shepherd, R; Fulkerson, E S; James, L; Emig, J; Norman, D

    2012-05-02

    Ultra fast x-ray streak cameras are a staple for time resolved x-ray measurements. There is a need for a ten inch manipulator (TIM) based streak camera that can be fielded in a newer large scale laser facility. The LLNL ultra fast streak camera's drive electronics have been upgraded and redesigned to fit inside a TIM tube. The camera also has a new user interface that allows for remote control and data acquisition. The system has been outfitted with a new sensor package that gives the user more operational awareness and control.

  14. Emissivity spectrum of a large "dark streak" from themis infrared imagery

    SciTech Connect

    Brumby, Steven P.; Vaniman, D. T.; Bish, D. L.

    2003-01-01

    'Dark streaks', also known as 'slope streaks', are unusual surface features found on Mars that are known to appear and fade away on timescales of years. Various explanations have been proposed for their origin and composition, including dry avalanches and wet debris or precipitates from brines. Previous investigations have been based on analysis of panchromatic imagery and altimetry from Viking and Mars Global Surveyor missions. We have obtained an infrared emissivity spectrum of a large dark streak on the north western edge of Olympus Mons, using imagery from the THEMIS instrument on the Mars Odyssey 2001 spacecraft.

  15. MaizeGDB: The Maize Genetics and Genomics Database.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the community database for biological information about the crop plant Zea mays. Genomic, genetic, sequence, gene product, functional characterization, literature reference, and person/organization contact information are among the datatypes stored at MaizeGDB. At the project’s website...

  16. Genetic mechanisms of Maize dwarf mosaic virus resistance in maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize resistance to viruses has been well-characterized at the genetic level, and loci responsible for resistance to potyviruses including Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), Sorghum mosaic virus (SrMV), and Johnsongrass mosaic virus (JGMV), have been mapped in several ge...

  17. MaizeGDB: The Maize Genetics and Genomics Database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the community database for biological information about the crop plant Zea mays. Genetic, genomic, sequence, gene product, functional characterization, literature reference, and person/organization contact information are among the datatypes stored at MaizeGDB. At the project's website...

  18. Streak camera recording of shock wave transit times at large distances using laser illumination

    NASA Astrophysics Data System (ADS)

    Tyburczy, J. A.; Blayney, J. L.; Miller, W. F.; Ahrens, T. J.

    1984-09-01

    A pulsed laser illumination system for streak camera recording of impact-induced shock wave transit times (˜1 μs) during impact experiments is described. Laser illumination of centimeter-sized subjects offers many advantages over diffuse illumination techniques for streak photography. Source-to-sample and sample-to-camera distances of ˜100 to 102 m can be employed. Light filtering, and simultaneous recording of both the impact event and the camera streak rate calibration, can be carried out easily. For use in such a system we describe a Pockels cell controller in which the reference 10-MHz oscillator signal is synchronously divided down to 38 Hz to provide a trigger signal for laser and streak camera testing.

  19. Effect of Process Variables on the Formation of Streak Defects on Anodized Aluminum Extrusions: An Overview

    NASA Astrophysics Data System (ADS)

    Zhu, Hanliang; Couper, Malcolm J.; Dahle, Arne K.

    2012-04-01

    Streak defects are often present on anodized extrusions of 6xxx series aluminum alloys, increasing the fabrication cost of these products. Moreover, streaking often only becomes visible after etching and anodizing treatments, rather than in the as-extruded condition, making it difficult to identify the original causes and influencing factors of these defects. In this paper, various process variables that influence the formation of streak defects on anodized aluminium extrusions are reviewed on the basis of a literature review, industrial practice and experimental results. The influencing factors involved in various processing steps such as billet quality, extrusion process, die design and etching process are considered. Effective measures for preventing the formation of streak defects in industrial extrusion products are discussed.

  20. Standard design for National Ignition Facility x-ray streak and framing cameras

    SciTech Connect

    Kimbrough, J. R.; Bell, P. M.; Bradley, D. K.; Holder, J. P.; Kalantar, D. K.; MacPhee, A. G.; Telford, S.

    2010-10-15

    The x-ray streak camera and x-ray framing camera for the National Ignition Facility were redesigned to improve electromagnetic pulse hardening, protect high voltage circuits from pressure transients, and maximize the use of common parts and operational software. Both instruments use the same PC104 based controller, interface, power supply, charge coupled device camera, protective hermetically sealed housing, and mechanical interfaces. Communication is over fiber optics with identical facility hardware for both instruments. Each has three triggers that can be either fiber optic or coax. High voltage protection consists of a vacuum sensor to enable the high voltage and pulsed microchannel plate phosphor voltage. In the streak camera, the high voltage is removed after the sweep. Both rely on the hardened aluminum box and a custom power supply to reduce electromagnetic pulse/electromagnetic interference (EMP/EMI) getting into the electronics. In addition, the streak camera has an EMP/EMI shield enclosing the front of the streak tube.

  1. Standard design for National Ignition Facility x-ray streak and framing camerasa)

    NASA Astrophysics Data System (ADS)

    Kimbrough, J. R.; Bell, P. M.; Bradley, D. K.; Holder, J. P.; Kalantar, D. K.; MacPhee, A. G.; Telford, S.

    2010-10-01

    The x-ray streak camera and x-ray framing camera for the National Ignition Facility were redesigned to improve electromagnetic pulse hardening, protect high voltage circuits from pressure transients, and maximize the use of common parts and operational software. Both instruments use the same PC104 based controller, interface, power supply, charge coupled device camera, protective hermetically sealed housing, and mechanical interfaces. Communication is over fiber optics with identical facility hardware for both instruments. Each has three triggers that can be either fiber optic or coax. High voltage protection consists of a vacuum sensor to enable the high voltage and pulsed microchannel plate phosphor voltage. In the streak camera, the high voltage is removed after the sweep. Both rely on the hardened aluminum box and a custom power supply to reduce electromagnetic pulse/electromagnetic interference (EMP/EMI) getting into the electronics. In addition, the streak camera has an EMP/EMI shield enclosing the front of the streak tube.

  2. Incidence of Fusarium Species and Mycotoxins in Silage Maize

    PubMed Central

    Eckard, Sonja; Wettstein, Felix E.; Forrer, Hans-Rudolf; Vogelgsang, Susanne

    2011-01-01

    Maize is frequently infected by the Fusarium species producing mycotoxins. Numerous investigations have focused on grain maize, but little is known about the Fusarium species in the entire plant used for silage. Furthermore, mycotoxins persist during the ensiling process and thus endanger feed safety. In the current study, we analyzed 20 Swiss silage maize samples from growers’ fields for the incidence of Fusarium species and mycotoxins. The species spectrum was analyzed morphologically and mycotoxins were measured by LC-MS/MS. A pre-harvest visual disease rating showed few disease symptoms. In contrast, the infection rate of two-thirds of the harvest samples ranged from 25 to 75% and twelve different Fusarium species were isolated. The prevailing species were F. sporotrichioides, F. verticillioides and F. graminearum. No infection specificity for certain plant parts was observed. The trichothecene deoxynivalenol (DON) was found in each sample (ranging from 780 to 2990 µg kg−1). Other toxins detected in descending order were zearalenone, further trichothecenes (nivalenol, HT-2 and T-2 toxin, acetylated DON) and fumonisins. A generalized linear regression model containing the three cropping factors harvest date, pre-precrop and seed treatment was established, to explain DON contamination of silage maize. Based on these findings, we suggest a European-wide survey on silage maize. PMID:22069750

  3. Split ring resonator based THz-driven electron streak camera featuring femtosecond resolution

    PubMed Central

    Fabiańska, Justyna; Kassier, Günther; Feurer, Thomas

    2014-01-01

    Through combined three-dimensional electromagnetic and particle tracking simulations we demonstrate a THz driven electron streak camera featuring a temporal resolution on the order of a femtosecond. The ultrafast streaking field is generated in a resonant THz sub-wavelength antenna which is illuminated by an intense single-cycle THz pulse. Since electron bunches and THz pulses are generated with parts of the same laser system, synchronization between the two is inherently guaranteed. PMID:25010060

  4. Streak detection and analysis pipeline for space-debris optical images

    NASA Astrophysics Data System (ADS)

    Virtanen, Jenni; Poikonen, Jonne; Säntti, Tero; Komulainen, Tuomo; Torppa, Johanna; Granvik, Mikael; Muinonen, Karri; Pentikäinen, Hanna; Martikainen, Julia; Näränen, Jyri; Lehti, Jussi; Flohrer, Tim

    2016-04-01

    We describe a novel data-processing and analysis pipeline for optical observations of moving objects, either of natural (asteroids, meteors) or artificial origin (satellites, space debris). The monitoring of the space object populations requires reliable acquisition of observational data, to support the development and validation of population models and to build and maintain catalogues of orbital elements. The orbital catalogues are, in turn, needed for the assessment of close approaches (for asteroids, with the Earth; for satellites, with each other) and for the support of contingency situations or launches. For both types of populations, there is also increasing interest to detect fainter objects corresponding to the small end of the size distribution. The ESA-funded StreakDet (streak detection and astrometric reduction) activity has aimed at formulating and discussing suitable approaches for the detection and astrometric reduction of object trails, or streaks, in optical observations. Our two main focuses are objects in lower altitudes and space-based observations (i.e., high angular velocities), resulting in long (potentially curved) and faint streaks in the optical images. In particular, we concentrate on single-image (as compared to consecutive frames of the same field) and low-SNR detection of objects. Particular attention has been paid to the process of extraction of all necessary information from one image (segmentation), and subsequently, to efficient reduction of the extracted data (classification). We have developed an automated streak detection and processing pipeline and demonstrated its performance with an extensive database of semisynthetic images simulating streak observations both from ground-based and space-based observing platforms. The average processing time per image is about 13 s for a typical 2k-by-2k image. For long streaks (length >100 pixels), primary targets of the pipeline, the detection sensitivity (true positives) is about 90% for

  5. Characterization results from several commercial soft x-ray streak cameras

    SciTech Connect

    Stradling, G.L.; Studebaker, J.K.; Cavailler, C.; Launspach, J.; Planes, J.

    1986-01-01

    The spatio-temporal performance of four soft x-ray streak cameras has been characterized. The objective in evaluating the performance capability of these instruments is to enable us to optimize experiment designs, to encourage quantitative analysis of streak data and to educate the ultra high speed photography and photonics community about the x-ray detector performance which is available. These measurements have been made collaboratively over the space of two years at the Forge pulsed x-ray source at Los Alamos and at the Ketjak laser facility an CEA Limeil-Valenton. The x-ray pulse lengths used for these measurements at these facilities were 150 psec and 50 psec respectively. The results are presented as dynamically-measured modulation transfer functions. Limiting temporal resolution values were also calculated. Emphasis is placed upon shot noise statistical limitations in the analysis of the data. Space charge repulsion in the streak tube limits the peak flux at ultra short experiments duration times. This limit results in a reduction of total signal and a decrease in signal to noise ratio in the streak image. The four cameras perform well with 20 1p/mm resolution discernable in data from the French C650X, the Hadland X-Chron 540 and the Hamamatsu C1936X streak cameras. The Kentech x-ray streak camera has lower modulation and does not resolve below 10 1p/mm but has a longer photocathode. The C650X bi-lamellar design shows uniform high fidelity recording across both spatial and temporal dimensions. The other three streak cameras show resolution degradation off axis. This must be weighed against a 10X lower streak tube throughput for the C650X.

  6. Measurement of width and intensity of particle streaks in turbulent flows

    NASA Astrophysics Data System (ADS)

    Håkansson, Karl M. O.; Kvick, Mathias; Lundell, Fredrik; Prahl Wittberg, Lisa; Söderberg, L. Daniel

    2013-06-01

    Fibre streaks are observed in experiments with fibre suspensions in a turbulent half-channel flow. The preferential concentration methods, most commonly used to quantify preferential particle concentration, are in one dimension found to be concentration dependent. Two different new streak quantification methods are evaluated, one based on Voronoi analysis and the other based on artificial particles with an assigned fixed width. The width of the particle streaks and a measure of the intensity of the streaks, i.e. streakiness, are sought. Both methods are based on the auto-correlation of a signal, generated by summing images in the direction of the streaks. Common for both methods is a severe concentration dependency, verified in experiments keeping the flow conditions constant while the (very dilute) concentration of fibres is altered. The fixed width method is shown to be the most suitable method, being more robust and less computationally expensive. By assuming the concentration dependence to be related to random noise, an expression is derived, which is shown to make the streak width and the streakiness independent of the concentration even at as low concentrations as 0.05 particles per pixel column in an image. The streakiness is obtained by applying an artificial particle width equal to 20 % of the streak width. This artificial particle width is in this study found to be large enough to smoothen the correlation without altering the streakiness nor the streak width. It is concluded that in order to make quantitative comparisons between different experiments or simulations, the evaluation has to be performed with care and be very well documented.

  7. Intial synchroscan streak camera imaging at the A0 photoinjector

    SciTech Connect

    Lumpkin, A.H.; Ruan, J.; /Fermilab

    2008-04-01

    At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10 to 20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5-ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of {approx}1 ps over 10s of minutes. This allowed us to measure both the UV laser pulse train at 244 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 1 nC per micropulse. We also did electron beam bunch length vs. micropulse charge measurements to identify a significant e-beam micropulse elongation from 10 to 30 ps (FWHM) for charges from 1 to 4.6 nC. This effect is attributed to space-charge effects in the PC gun as reproduced by ASTRA calculations. Chromatic temporal dispersion effects in the optics were also characterized and will be reported.

  8. An Optical Streaking Method for Measuring Femtosecond Electron Bunches

    SciTech Connect

    Ding, Yuantao; Bane, Karl L.F.; Huang, Zhirong; /SLAC

    2011-12-14

    The measurement of the ultra-short electron bunch length on the femtosecond time scale constitutes a very challenging problem. In the x-ray free electron laser facilities such as the Linac Coherent Light Source, generation of a sub-ten femtoseconds electron beam with 20pC charge is possible, but direct measurements are very difficult due to the resolution limit of the present diagnostics. We propose a new method here based on the measurement of the electron beam energy modulation induced from laser-electron interaction in a short wiggler. A typical optical streaking method requires a laser wavelength much longer than the electron bunch length. In this paper a laser with its wavelength shorter than the electron bunch length has been adopted, while the slope on the laser intensity envelope is used to distinguish the different periods. With this technique it is possible to reconstruct the bunch longitudinal profile from a single shot measurement. Generation of ultrashort x-ray pulses at femtoseconds (fs) scale is of great interest within synchrotron radiation and free electron laser (FEL) user community. One of the simple methods is to operate the FEL facility at low charge. At the Linac Coherent Light Source (LCLS), we have demonstrated the capability of generating ultrashort electron-beam (e-beam) with a duration of less than 10 fs fwhm using 20 pC charge. The x-ray pulses have been delivered to the x-ray users with a similar or even shorter pulse duration. However, The measurement of such short electron or x-ray pulse length at the fs time-scale constitutes a challenging problem. A standard method using an S-band radio-frequency (rf) transverse deflector has been established at LCLS, which works like a streak camera for electrons and is capable of resolving bunch lengths as short as 25 fs fwhm. With this device, the electrons are transversely deflected by the high-frequency time-variation of the deflecting fields. Increasing the deflecting voltage and rf frequency

  9. Polar Dunes In Summer Exhibit Frost Patches, Wind Streaks

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Mars Global Surveyor passes over the north polar region of the red planet twelve times each day, offering many opportunities to observe how the polar cap frosts and dunes are changing as the days goby. Right now it is summer in the north. This picture, taken the second week of April 1999, shows darks and dunes and remnant patches of bright frost left over from the winter that ended in July 1998. Dark streaks indicate recent movement of sand. The picture covers an area only 1.4 kilometers (0.9 miles)across and is illuminated from the upper right.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  10. Optimizing Data Recording for the NIF Core Diagnostic X-ray Streak Camera

    SciTech Connect

    Kalantar, D H; Bell, P M; Perry, T S; Sewall, N; Diamond, C; Piston, K

    2000-06-13

    The x-ray streak camera is an important instrument for recording a continuous time history of x-ray emitted from laser target experiments. X-ray streak cameras were used to diagnose experiments in inertially confined fusion and high energy density sciences on the Nova laser. These streak cameras are now used for similar experiments conducted at the OMEGA laser facility, and cameras of this type will be used for experiments on the National Ignition Facility (NIF). The Nova x-ray streak cameras (SSCs) used a sealed optical image intensifier coupled to film to record the streaked x-ray data. In order to develop the core x-ray streak camera for NIF (ref Kimbrough) using a CCD based recording system, we evaluate the performance of the SSCs under a variety of detector configurations. We performed laboratory bench characterization tests of the SSCs to measure the spatial resolution and to evaluate the dynamic range and signal to noise for different configurations of the SSC. We present results of these tests here.

  11. Effects of streaking laser intensity on the characterization of isolated attosecond pulses

    NASA Astrophysics Data System (ADS)

    Wang, He; Khan, Sabih; Chini, Michael; Chen, Shouyuan; Chang, Zenghu

    2009-05-01

    Single isolated attosecond extreme ultraviolet (XUV) pulses can be characterized by streaking photoelectrons using a near infrared (NIR) laser field. Classically, the streaking resolution is determined by the Rayleigh criterion, which requires the minimum NIR intensity of 5.5x10^13 W/cm^2 to resolve 90 as XUV pulses. Under such high NIR intensity, the electrons generated from multi-photon processes overlap with the streaked electrons in the spectrogram, which unavoidably introduces errors in the final XUV reconstruction. When the FROG-CRAB (Frequency-Resolved Optical Gating for Complete Reconstruction of Attosecond Bursts) technique is used to reconstruct the XUV pulses from the spectrogram, it was found that the minimum streaking intensity needed to resolve single attosecond pulses is dependent on the maximum count of the spectrogram. With a peak count of 100 in the spectrogram, chirped attosecond pulses with spectral bandwidth supporting 90-as transform limited pulse durations can be retrieved from the spectrogram with streaking intensity two orders of magnitude smaller than that derived from the Rayleigh criterion. Such low streaking field intensity is desirable to suppress the ATI background, which is important for the characterization of even shorter XUV attosecond pulses because it significantly reduces the intensity constraints on the experiments.

  12. New observations of Bolivian wind streaks by JPL Airborne SAR: Preliminary results

    NASA Technical Reports Server (NTRS)

    Blumberg, Dan G.; Greeley, Ronald

    1995-01-01

    In 1993 NASA's Jet Propulsion Laboratory Airborne Synthetic Aperture Radar system (AIRSAR) was deployed to South America to collect multi-parameter radar data over pre-selected targets. Among the sites targeted was a series of wind streaks located in the Altiplano of Bolivia. The objective of this investigation is to study the effect of wavelength, polarization, and incidence angle on the visibility of wind streaks in radar data. Because this is a preliminary evaluation of the recently acquired data we will focus on one scene and, thus, only on the effects of wavelength and polarization. Wind streaks provide information on the near-surface prevailing winds and on the abundance of winderodible material, such as sand. The potential for a free-flyer radar system that could provide global radar images in multiple wavelengths, polarizations, and incidence angles requires definition of system parameters for mission planning. Furthermore, thousands of wind streaks were mapped from Magellan radar images of Venus; their interpretation requires an understanding of the interaction of radar with wind streaks and the surrounding terrain. Our experiment was conducted on wind streaks in the Altiplano of Bolivia to address these issues.

  13. On the origin and evolution of streaks in polymeric shear flows

    NASA Astrophysics Data System (ADS)

    Page, Jacob; Zaki, Tamer

    2013-11-01

    Streaks are a ubiquitous feature in transitional shear flows of both Newtonian and complex fluids. A model problem is formulated where streaks are generated in response to forcing by a decaying streamwise vortex in an Oldroyd-B fluid, and the effects of inertia and elasticity are examined. The dynamics are found to be largely governed by a single parameter: the ratio of the solvent diffusion to the polymer relaxation timescales. When the time scales are disparate, the ``quasi-Newtonian'' and ``elastic'' dynamics can be distinguished. The ``quasi-Newtonian'' evolution of the streaks in the polymeric flow matches the Newtonian equivalent at the same total (solvent) Reynolds number when polymer relaxation is very fast (slow). The ``elastic'' response is significant, when the polymer relaxation time is long, and leads to significant streak amplification even with very weak inertia. When the diffusion and polymer relaxation timescales are commensurate, the streaks are re-energised in a periodic cycle. This behaviour is enhanced in the instantaneously elastic limit where the governing equation reduces to a wave equation with harmonic forcing. The streak re-energisation is demonstrated to be a superposition of trapped inertio-elastic shear waves.

  14. Spatial relationships among the cellular tapetum, visual streak and rod density in dogs

    PubMed Central

    YAMAUE, Yasuhiro; HOSAKA, Yoshinao Z.; UEHARA, Masato

    2014-01-01

    The dog visual system is well suited to dim light conditions due to rod-dominated retina and the reflective tapetum. The topographical distributions of rods and thickness of the tapetum of the dog were quantified in retinal whole mounts stained with thionine, and spatial relationships among the tapetum, rod density and visual streak of high ganglion cell density were elucidated. The relationship between the retina and tapetum was analyzed in parasagittal sections stained with thionine or hematoxylin-eosin. The tapetum was thick in its center, and the thickest part consisted of 9 to 12 tapetal cell layers. Rod density ranged from 200,000 to 540,000/mm2. Maximum rod density was found in the area dorsal to the visual streak, and the density in that area was significantly higher than the rod density in the visual streak and accorded spatially with the thickest part of the tapetum. The horizontal visual streak was found over the horizontal line through the optic disc in the temporal half and extended slightly into the nasal half. The central area of the highest density of ganglion cells was approximately located midway between the nasal and temporal ends of the visual streak. The visual streak was located within the tapetal area, but ventrally to the thick part of the tapetum. PMID:25728250

  15. Maize rhabdovirus-vector transmission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    oth of the plant-infecting rhabdovirus genera, Nucleorhabdovirus and Cytorhabdovirus, contain viruses that infect maize (Zea mays L.). The maize infecting rhabdoviruses are transmitted by hemipteran insects in the families Cicadellidae and Delphacidae in a persistent propagative manner. This chapt...

  16. Maize Genetics and Genomics Database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This report is provided each year to our stakeholders in the maize genetic community. In this report, we describe the five-year plan for MaizeGDB reviewed in early 2008 by the USDA-ARS peer review process and which was developed with inputs from our Working Group and the Allerton 2007 Report (MNL 82...

  17. AN INTEGRATED MAP FOR MAIZE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Maize Mapping Project (MMP) is focused on developing genetic, physical, and database resources for the maize genome. A key resource being developed by the MMP is a well-integrated genetic and physical map that will expedite the identification of DNA sequences underlying key traits that have been...

  18. The MaizeGDB Genome Browser

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB (http://www.maizegdb.org) is the community database for maize genetics and genomics. As part of an effort to develop MaizeGDB as a more sequence-centric resource, we implemented a genome browser based on information we gathered by surveying the community of maize geneticists. Based on commu...

  19. Metabolic pathway resources at MaizeGDB

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two maize metabolic networks are available at MaizeGDB: MaizeCyc (http://maizecyc.maizegdb.org, also at Gramene) and CornCyc (http://corncyc.maizegdb.org, also at the Plant Metabolic Network). MaizeCyc was developed by Gramene, and CornCyc by the Plant Metabolic Network, both in collaboration with M...

  20. Maize variety and method of production

    DOEpatents

    Pauly, Markus; Hake, Sarah; Kraemer, Florian J

    2014-05-27

    The disclosure relates to a maize plant, seed, variety, and hybrid. More specifically, the disclosure relates to a maize plant containing a Cal-1 allele, whose expression results in increased cell wall-derived glucan content in the maize plant. The disclosure also relates to crossing inbreds, varieties, and hybrids containing the Cal-1 allele to produce novel types and varieties of maize plants.

  1. Seasonal and secular variation of wind streaks on Mars - An analysis of Mariner 9 and Viking data

    NASA Technical Reports Server (NTRS)

    Thomas, P.; Veverka, J.

    1979-01-01

    Viking orbiter observations extending over 1 Martian year have been used in conjunction with Mariner 9 data obtained in 1971-1972 to study the seasonal and secular behavior of several kinds of wind streaks. Most bright streaks, inferred to consist of dust storm fallout in the lees of obstacles, have changed very little in form or orientation over a period of 3 Martian years. Some are extremely stable and have experienced no effective eolian action over the 3 years. A few bright streaks changed rapidly during global dust storms; these streaks are located in areas subject to both global and topographic winds. Viking images have shown for the first time that dark, erosional streaks are stable from the time of their formation after major dust storms until the onset of the next episode of major storm activity. Available evidence shows that the large, dark streaks in Oxia Palus consist of material deflated from dune fields within the associated craters. These streaks lengthened secularly since 1972; changes appear to occur episodically during southern summer. The great majority of all streaks reflect winds during the period from late southern spring to early southern fall, although some changes occur throughout the year. The global pattern of wind streaks and the variability of the streaks thus depend strongly upon the current south-north asymmetry of seasons on Mars.

  2. Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

    1999-01-01

    Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

  3. Genetic erosion in maize's center of origin.

    PubMed

    Dyer, George A; López-Feldman, Alejandro; Yúnez-Naude, Antonio; Taylor, J Edward

    2014-09-30

    Crop genetic diversity is an indispensable resource for farmers and professional breeders responding to changing climate, pests, and diseases. Anecdotal appraisals in centers of crop origin have suggested serious threats to this diversity for over half a century. However, a nationwide inventory recently found all maize races previously described for Mexico, including some formerly considered nearly extinct. A flurry of social studies seems to confirm that farmers maintain considerable diversity. Here, we compare estimates of maize diversity from case studies over the past 15 y with nationally and regionally representative matched longitudinal data from farmers across rural Mexico. Our findings reveal an increasing bias in inferences based on case study results and widespread loss of diversity. Cross-sectional, case study data suggest that farm-level richness has increased by 0.04 y(-1) nationwide; however, direct estimates using matched longitudinal data reveal that richness dropped -0.04 y(-1) between 2002 and 2007, from 1.43 to 1.22 varieties per farm. Varietal losses occurred across regions and altitudinal zones, and regardless of farm turnover within the sector. Extinction of local maize populations may not have resulted in an immediate loss of alleles, but low varietal richness and changes in maize's metapopulation dynamics may prevent farmers from accessing germplasm suitable to a rapidly changing climate. Declining yields could then lead farmers to leave the sector and result in a further loss of diversity. Similarities in research approaches across crops suggest that methodological biases could conceal a loss of diversity at other centers of crop origin. PMID:25197088

  4. Intravitreal bevacizumab for choroidal neovascularization secondary to angioid streaks: A report of two patients

    PubMed Central

    Ozkaya, Abdullah; Alkin, Zeynep; Faiz, Miray; Yazici, Ahmet Taylan; Demirok, Ahmet

    2013-01-01

    The aim of this study is to report clinical course of choroidal neovascularization secondary to angioid streaks (AS) in two patients who underwent intravitreal bevacizumab therapy. Fundus examination, fluorescein angiography (FA) and optical coherence tomography (OCT) revealed the diagnosis of subfoveal classic choroidal neovascularization (CNV) in the right eye in patient 1 and in the left eye in patient 2. After three consecutive bevacizumab injections, visual acuity improved from 20/40 to 20/25 in patient 1 and from 20/80 to 20/50 in patient 2. After 3 months of therapy, additional bevacizumab injection was administered when the lesion showed recurrence. After a follow-up time of 24-months, patient 1 received 14 intravitreal bevacizumab injections; patient 2 received only 4 injections. Visual acuities remained stable at 20/32 and 20/50 in patient 1 and patient 2, respectively. Though, the patients of CNV secondary to AS showed similar clinical appearance at the beginning, this report provides the data for different responses to intravitreal bevacizumab therapy. While fewer injections were required to control the disease in one patient, the other patient needed much more injections for stabilization of the CNV. Further studies are required to understand the cause of varied treatment responses in those patients. PMID:25473350

  5. Registration of OhVRS-1 Maize Synthetic Population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The OhVRS-1 maize (Zea mays L.) population was developed by the USDA Corn and Soybean Research Unit at the Ohio Agricultural Research and Development Center in Wooster, OH, and released as a germplasm resource for resistance to virus diseases. It is a synthetic population made up of tropical and co...

  6. Root Infection and Systemic Colonization of Maize by Colletotrichum graminicola▿

    PubMed Central

    Sukno, Serenella A.; García, Verónica M.; Shaw, Brian D.; Thon, Michael R.

    2008-01-01

    Colletotrichum graminicola is a filamentous ascomycete that causes anthracnose disease of maize. While the fungus can cause devastating foliar leaf blight and stalk rot diseases, little is known about its ability to infect roots. Previously published reports suggest that C. graminicola may infect maize roots and that root infections may contribute to the colonization of aboveground plant tissues, leading to disease. To determine whether C. graminicola can infect maize roots and whether root infections can result in the colonization of aboveground plant tissues, we developed a green fluorescent protein-tagged strain and used it to study the plant root colonization and infection process in vivo. We observed structures produced by other root pathogenic fungi, including runner hyphae, hyphopodia, and microsclerotia. A mosaic pattern of infection resulted from specific epidermal and cortical cells becoming infected by intercellular hyphae while surrounding cells were uninfected, a pattern that is distinctly different from that described for leaves. Interestingly, falcate conidia, normally restricted to acervuli, were also found filling epidermal cells and root hairs. Twenty-eight percent of plants challenged with soilborne inoculum became infected in aboveground plant parts (stem and/or leaves), indicating that root infection can lead to asymptomatic systemic colonization of the plants. Many of the traits observed for C. graminicola have been previously reported for other root-pathogenic fungi, suggesting that these traits are evolutionally conserved in multiple fungal lineages. These observations suggest that root infection may be an important component of the maize anthracnose disease cycle. PMID:18065625

  7. Aflatoxin resistance in maize: what have we learned lately?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxin contamination of maize grain is a huge economic and health problem, causing death and increased disease burden in much of the developing world and income loss in the developed world. Despite the gravity of the problem, deployable solutions are still being sought. In the past 15 years, much...

  8. Chiral oily streaks in a smectic-A liquid crystal.

    PubMed

    Nemitz, Ian R; Ferris, Andrew J; Lacaze, Emmanuelle; Rosenblatt, Charles

    2016-08-21

    The liquid crystal octylcyanobiphenyl (8CB) was doped with the chiral agent CB15 and spin-coated onto a substrate treated for planar alignment of the director, resulting in a film of thickness several hundred nm in the smectic-A phase. In both doped and undoped samples, the competing boundary conditions - planar alignment at the substrate and vertical alignment at the free surface - cause the liquid crystal to break into a series of flattened hemicylinders to satisfy the boundary conditions. When viewed under an optical microscope with crossed polarizers, this structure results in a series of dark and light stripes ("oily streaks") of period ∼1 μm. In the absence of chiral dopant the stripes run perpendicular to the substrate's easy axis. However, when doped with chiral CB15 at concentrations up to c = 4 wt%, the stripe orientation rotates by a temperature-dependent angle φ with respect to the c = 0 stripe orientation, where φ increases monotonically with c. φ is largest just below the nematic - smectic-A transition temperature TNA and decreases with decreasing temperature. As the temperature is lowered, φ relaxes to a steady-state orientation close to zero within ∼1 °C of TNA. We suggest that the rotation phenomenon is a manifestation of the surface electroclinic effect: The rotation is due to the weak smectic order parameter and resulting large director tilt susceptibility with respect to the smectic layer normal near TNA, in conjunction with an effective surface electric field due to polar interactions between the liquid crystal and substrate. PMID:27426740

  9. Mars Eolian Geology at Airphoto Scales: The Large Wind Streaks of Western Arabia Terra

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.

    2001-01-01

    More than 27,000 pictures at aerial photograph scales (1.5-12 m/pixel) have been acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) since September 1997. The pictures are valuable for testing hypotheses about geologic history and processes of Mars. Of particular interest are eolian features connected to surface albedo patterns. This work is focused on low-albedo wind streaks, some over 100 km long, in western Arabia Terra. Each streak is widest where it originates at an impact crater (typically 25-150 km diameter). The streaks taper downwind. Within the associated craters there is a lower-albedo surface that, in nearly all observed cases, includes barchan dunes indicative of transport in the same direction as the wind streaks. Upwind of the dunes there is usually an outcrop of layered material that might have served as a source for dune sand. MOC images show that the west Arabia streaks consist of a smooth-surfaced, multiple-meters-thick, mantle (smooth at 1.5 m/pixel) that appears to be superposed on local surfaces. No dunes are present, indicating that down-streak transport of sediment via saltation and traction have not occurred. Two models might explain the observed properties: (1) the streaks consist of dark silt- and clay-sized grains deflated from the adjacent crater interiors and deposited from suspension or (2) they are remnants (protected in the lee of impact crater rims) of a formerly much larger, regional covering of low albedo, smooth-surfaced mantle. The latter hypothesis is based on observation of low albedo mantled surfaces occurring south of west Arabia in Terra Meridiani. For reasons yet unknown, a large fraction of the martian equatorial regions are covered by low albedo, mesa-forming material that lies unconformably atop eroded layered and cratered terrain. Both hypotheses are being explored via continued selective targeting of new MOC images as well as analyses of the new data.

  10. Dust Devils Seen Streaking Across Mars: PART 1--What Are These?

    NASA Technical Reports Server (NTRS)

    2000-01-01

    PIA02376 [figure removed for brevity, see original site]

    PIA02377 [figure removed for brevity, see original site]

    Dark streaks, everywhere! Many Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of the middle latitudes of the northern and southern hemispheres of Mars show wild patterns of criss-crossing dark streaks. Many of these streaks are straight and narrow, others exhibit curly arcs, twists, and loops. They often cross over hills, run straight across dunes and ripples, and go through fields of house-sized boulders. The two examples shown above were acquired in the last three months. Both pictures are illuminated by sunlight from the upper left. The first picture (left), showing dark streaks on the rippled flats of Argyre Planitia, covers an area 3 km by 5 km (1.9 by 3.1 miles) at a latitude of 51oS. The second picture (right) shows an area approximately 3 km by 5 km in Promethei Terra at a latitude of 58oS.

    For many months the MOC science team was seeing streaks such as these, but were uncertain how they formed. One speculation was that they might result from the passage of dust devils. Each dust devil would leave a dark streak by removing bright dust from the terrain in its path, revealing a darker surface underneath. An image described by the MOC team in July 1998 showed examples of streaks that were, at the time, speculated to be caused by dust devils.

  11. Effects of elevated [CO2 ] on maize defence against mycotoxigenic Fusarium verticillioides.

    PubMed

    Vaughan, Martha M; Huffaker, Alisa; Schmelz, Eric A; Dafoe, Nicole J; Christensen, Shawn; Sims, James; Martins, Vitor F; Swerbilow, Jay; Romero, Maritza; Alborn, Hans T; Allen, Leon Hartwell; Teal, Peter E A

    2014-12-01

    Maize is by quantity the most important C4 cereal crop; however, future climate changes are expected to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce productivity. While rising atmospheric [CO2 ] is a driving force behind the warmer temperatures and drought, which aggravate fungal disease and mycotoxin accumulation, our understanding of how elevated [CO2 ] will effect maize defences against such pathogens is limited. Here we report that elevated [CO2 ] increases maize susceptibility to Fusarium verticillioides proliferation, while mycotoxin levels are unaltered. Fumonisin production is not proportional to the increase in F. verticillioides biomass, and the amount of fumonisin produced per unit pathogen is reduced at elevated [CO2 ]. Following F. verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones and downstream phytoalexins is dampened in maize grown at elevated [CO2 ]. The attenuation of maize 13-LOXs and jasmonic acid production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2 ]. Our findings suggest that elevated [CO2 ] will compromise maize LOX-dependent signalling, which will influence the interactions between maize and mycotoxigenic fungi. PMID:24689748

  12. The sedimentology and dynamics of crater-affiliated wind streaks in western Arabia Terra, Mars and Patagonia, Argentina

    USGS Publications Warehouse

    Rodriguez, J.A.P.; Tanaka, K.L.; Yamamoto, A.; Berman, D.C.; Zimbelman, J.R.; Kargel, J.S.; Sasaki, S.; Jinguo, Y.; Miyamoto, H.

    2010-01-01

    Wind streaks comprise recent aeolian deposits that have been extensively documented on Venus, Earth and Mars. Martian wind streaks are among the most abundant surface features on the planet and commonly extend from the downwind margins of impact craters. Previous studies of wind streaks emerging from crater interior deposits suggested that the mode of emplacement was primarily related to the deposition of silt-sized particles as these settled from plumes. We have performed geologic investigations of two wind streaks clusters; one situated in western Arabia Terra, a region in the northern hemisphere of Mars, and another in an analogous terrestrial site located in southern Patagonia, Argentina, where occurrences of wind streaks emanate from playas within maar craters. In both these regions we have identified bedforms in sedimentary deposits on crater floors, along wind-facing interior crater margins, and along wind streaks. These observations indicate that these deposits contain sand-sized particles and that sediment migration has occurred via saltation from crater interior deposits to wind streaks. In Arabia Terra and in Patagonia wind streaks initiate from crater floors that contain lithic and evaporitic sedimentary deposits, suggesting that the composition of wind streak source materials has played an important role in development. Spatial and topographic analyses suggest that regional clustering of wind streaks in the studied regions directly correlates to the areal density of craters with interior deposits, the degree of proximity of these deposits, and the craters' rim-to-floor depths. In addition, some (but not all) wind streaks within the studied clusters have propagated at comparable yearly (Earth years) rates. Extensive saltation is inferred to have been involved in its propagation based on the studied terrestrial wind streak that shows ripples and dunes on its surface and the Martian counterpart changes orientation toward the downslope direction where it

  13. Exploiting the combination of natural and genetically engineered resistance to cassava mosaic and cassava brown streak viruses impacting cassava production in Africa.

    PubMed

    Vanderschuren, Hervé; Moreno, Isabel; Anjanappa, Ravi B; Zainuddin, Ima M; Gruissem, Wilhelm

    2012-01-01

    Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) are currently two major viral diseases that severely reduce cassava production in large areas of Sub-Saharan Africa. Natural resistance has so far only been reported for CMD in cassava. CBSD is caused by two virus species, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). A sequence of the CBSV coat protein (CP) highly conserved between the two virus species was used to demonstrate that a CBSV-CP hairpin construct sufficed to generate immunity against both viral species in the cassava model cultivar (cv. 60444). Most of the transgenic lines showed high levels of resistance under increasing viral loads using a stringent top-grafting method of inoculation. No viral replication was observed in the resistant transgenic lines and they remained free of typical CBSD root symptoms 7 month post-infection. To generate transgenic cassava lines combining resistance to both CBSD and CMD the hairpin construct was transferred to a CMD-resistant farmer-preferred Nigerian landrace TME 7 (Oko-Iyawo). An adapted protocol allowed the efficient Agrobacterium-based transformation of TME 7 and the regeneration of transgenic lines with high levels of CBSV-CP hairpin-derived small RNAs. All transgenic TME 7 lines were immune to both CBSV and UCBSV infections. Further evaluation of the transgenic TME 7 lines revealed that CBSD resistance was maintained when plants were co-inoculated with East African cassava mosaic virus (EACMV), a geminivirus causing CMD. The innovative combination of natural and engineered virus resistance in farmer-preferred landraces will be particularly important to reducing the increasing impact of cassava viral diseases in Africa. PMID:23049780

  14. Roles of Stolbur phytoplasma and Reptalus panzeri (Cixiinae, Auchenorrhyncha) in the epidemiology of Maize redness in Serbia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40-90% in southern Banat, Serbia. MR was recently associated with the presence of th...

  15. mRNA isoforms in the maize endophyte/pathogen Fusarium verticillioides: And a little story about KP4

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The filamentous fungus Fusarium verticillioides is a pathogen and endophyte of maize. At some stages of its life, it may synthesize a family of mycotoxins called fumonisins that may contaminate maize products. Ingestion of fumonisin is linked to a variety of animal diseases including cancer in som...

  16. Proteomic analysis of the maize rachis: Potential roles of constitutive and induced proteins in resistance to Aspergillus flavus and aflatoxin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infection of the maize (Zea mays L.) with aflatoxigenic fungus Aspergillus flavus and consequent contamination with carcinogenic aflatoxin is a persistent and serious agricultural problem causing disease and significant crop losses worldwide. The rachis (cob) is an important structure of maize ear ...

  17. Roles of Stolbur Phytoplasma and Reptalus Panzeri (Cixiinae, Auchenorrhyncha) in the Epidemiology of Maize Redness in Serbia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40-90% in southern Banat, Serbia. MR was recently associated with the presence of th...

  18. Ets2-dependent trophoblast signalling is required for gastrulation progression after primitive streak initiation.

    PubMed

    Polydorou, Christiana; Georgiades, Pantelis

    2013-01-01

    Although extraembryonic ectoderm trophoblast signals the embryo for primitive streak initiation, a prerequisite for gastrulation, it is unknown whether it also signals for the progression of gastrulation after primitive streak initiation. Here, using Ets2-/- mice, we show that trophoblast signalling is also required in vivo for primitive streak elongation, completion of intraembryonic mesoderm epithelial-mesenchymal transition and the development of anterior primitive streak derivatives such as the node. We show that Ets2-dependent trophoblast signalling is required for the maintenance of high levels of Nodal and Wnt3 expression in the epiblast and for the induction of Snail expression in the primitive streak, between embryonic day 6.3 and 6.7. Within extraembryonic ectoderm trophoblast, Ets2 maintains the expression of the transcription factors Elf5, Cdx2 and Eomes, and that of the signalling molecule Bmp4. We propose a model that provides a genetic explanation as to how Ets2 in trophoblast mediates the progression of gastrulation within the epiblast. PMID:23552073

  19. Comparative analysis of virus-derived small RNAs within cassava (Manihot esculenta Crantz) infected with cassava brown streak viruses

    PubMed Central

    Ogwok, Emmanuel; Ilyas, Muhammad; Alicai, Titus; Rey, Marie E.C.; Taylor, Nigel J.

    2016-01-01

    Infection of plant cells by viral pathogens triggers RNA silencing, an innate antiviral defense mechanism. In response to infection, small RNAs (sRNAs) are produced that associate with Argonaute (AGO)-containing silencing complexes which act to inactivate viral genomes by posttranscriptional gene silencing (PTGS). Deep sequencing was used to compare virus-derived small RNAs (vsRNAs) in cassava genotypes NASE 3, TME 204 and 60444 infected with the positive sense single-stranded RNA (+ssRNA) viruses cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), the causal agents of cassava brown streak disease (CBSD). An abundance of 21–24 nt vsRNAs was detected and mapped, covering the entire CBSV and UCBSV genomes. The 21 nt vsRNAs were most predominant, followed by the 22 nt class with a slight bias toward sense compared to antisense polarity, and a bias for adenine and uracil bases present at the 5′-terminus. Distribution and frequency of vsRNAs differed between cassava genotypes and viral genomes. In susceptible genotypes TME 204 and 60444, CBSV-derived sRNAs were seen in greater abundance than UCBSV-derived sRNAs. NASE 3, known to be resistant to UCBSV, accumulated negligible UCBSV-derived sRNAs but high populations of CBSV-derived sRNAs. Transcript levels of cassava homologues of AGO2, DCL2 and DCL4, which are central to the gene-silencing complex, were found to be differentially regulated in CBSV- and UCBSV-infected plants across genotypes, suggesting these proteins play a role in antiviral defense. Irrespective of genotype or viral pathogen, maximum populations of vsRNAs mapped to the cytoplasmic inclusion, P1 and P3 protein-encoding regions. Our results indicate disparity between CBSV and UCBSV host-virus interaction mechanisms, and provide insight into the role of virus-induced gene silencing as a mechanism of resistance to CBSD. PMID:26811902

  20. Intravitreal ranibizumab for bilateral choroidal neovascularisation in a patient with angioid streaks

    PubMed Central

    Yilmaz, Ihsan; Ozkaya, Abdullah; Alkin, Zeynep; Yazici, Ahmet Taylan

    2014-01-01

    Angioid streaks are described as irregular lines deep into the retina, configured in a radiating fashion which results from breaks in Bruch’s membrane. Optic nerve head drusen are acellular, globular deposits located within the optic nerve head. Angioid streaks and optic nerve head drusen may coexist in patients with pseudoxanthoma elasticum. Both disorders may cause choroidal neovascularisation. In this case report we aimed to present a 48-year-old man with pseudoxanthoma elasticum. The patient had bilateral choroidal neovascularisation secondary to angioid streaks and was treated with intravitreal ranibizumab injections. Visual acuity was increased and maintained at the same level during the follow-up time. There was no complication related to the injection. PMID:25073527

  1. Effects of diabatic heating on the ageostrophic circulation of an upper tropospheric jet streak

    NASA Technical Reports Server (NTRS)

    Keyser, D. A.; Johnson, D. R.

    1984-01-01

    Higher temporal resolution data from NASA's fourth Atmospheric Variability Experiment (April 24-25, 1975) are used to study the role of diabatic heating within the convective region in altering the ageostrophic mass circulation in the entrance region of the jet streak. The modifying effect this diabatic heating in the mesoscale storm exerts on the synoptic-scale environmental flow through dynamical mechanisms which link the mass circulation of these two scales is examined. The effect of diabatic heating on the ageostrophic motion within the thermally direct circulation of the jet streak and the mesoscale convective complexes is investigated. Diabatic modes of ageostrophic motion that intensify the upper tropospheric jet streak downstream are identified.

  2. Critical evaluation of attosecond time delays retrieved from photoelectron streaking measurements

    NASA Astrophysics Data System (ADS)

    Wei, Hui; Morishita, Toru; Lin, C. D.

    2016-05-01

    A photoelectron streaking experiment which was conceived as a means to extract the electron wave packet of single-photon ionization has also been employed to retrieve time delays in the fundamental photoemission processes. The discrepancies between the time delays thus measured and those from many sophisticated theoretical calculations have generated a great deal of controversy in recent years. Here we present a careful examination of the methods that were used to retrieve the time delays and demonstrate the difficulty of achieving an accuracy of the retrieved time delays of a few to tens of attoseconds in typical streaking measurements. The difficulty owes more to the lower sensitivity of the streaking spectra to the phase of the photoionization transition dipole than to the spectral phase of the attosecond light pulse in the experiment. The retrieved time delay contains extra errors when the attochirp of the attosecond pulse is large so that the dipole phase becomes negligible compared to it.

  3. Impact of laser phase and amplitude noises on streak camera temporal resolution

    SciTech Connect

    Wlotzko, V.; Uhring, W.; Summ, P.

    2015-09-15

    Streak cameras are now reaching sub-picosecond temporal resolution. In cumulative acquisition mode, this resolution does not entirely rely on the electronic or the vacuum tube performances but also on the light source characteristics. The light source, usually an actively mode-locked laser, is affected by phase and amplitude noises. In this paper, the theoretical effects of such noises on the synchronization of the streak system are studied in synchroscan and triggered modes. More precisely, the contribution of band-pass filters, delays, and time walk is ascertained. Methods to compute the resulting synchronization jitter are depicted. The results are verified by measurement with a streak camera combined with a Ti:Al{sub 2}O{sub 3} solid state laser oscillator and also a fiber oscillator.

  4. Unsteady hot streak simulation through a 1-1/2 stage turbine engine

    NASA Astrophysics Data System (ADS)

    Takahashi, R. K.; Ni, R. H.

    1991-06-01

    The temperature redistribution process in a 1-1/2 stage turbine (consisting of a first stator, first rotor, and second stator) was analyzed using an unsteady 3D Euler flow solver. The study concentrated on tracking a hot streak from the inlet of the first stator to the exit of the second stator. The redistribution of the hot streak in the second stator passage was very different from that in the rotor passage, with no signs of temperature segregation in the second stator passage, and with rotor-generated vortices which persist through the second stator passage and partake in redistributing the remains of the hot streak. The unsteady code predicts different time-averaged temperatures and secondary flow in the second stator passage than in the steady multistage code, although the steady code may be sufficient for predicting time-averaged pressure loadings on both rotor and second stator airfoils, and time-averaged secondary flow vortices in the rotor passage.

  5. Imaging plasmonic fields near gold nanospheres in attosecond time-resolved streaked photoelectron spectra

    NASA Astrophysics Data System (ADS)

    Li, Jianxiong; Thumm, Uwe

    2016-05-01

    To study time-resolved photoemission from gold nanospheres, we introduce a quantum-mechanical approach, including the plasmonic near-field-enhancement of the streaking field at the surface of the nanosphere. We use Mie theory to calculate the plasmonically enhanced fields near 10 to 200 nm gold nanospheres, driven by incident near infrared (NIR) or visible laser pulses. We model the gold conduction band in terms of a spherical square well potential. Our simulated streaked photoelectron spectra reveal a plasmonic amplitude enhancement and phase shift related to calculations that exclude the induced plasmonic field. The phase shift is due to the plasma resonance. This suggests the use of streaked photoelectron spectroscopy for imaging the dielectric response and plasmonic field near nanoparticles. Supported by the NSD-EPSCoR program, NSF, and the USDoE.

  6. Absolute calibration method for fast-streaked, fiber optic light collection, spectroscopy systems.

    SciTech Connect

    Johnston, Mark D.; Frogget, Brent; Oliver, Bryan Velten; Maron, Yitzhak; Droemer, Darryl W.; Crain, Marlon D.

    2010-04-01

    This report outlines a convenient method to calibrate fast (<1ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such a system is used to collect spectral data on plasmas generated in the A-K gap of electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA). On RITS, light is collected through a small diameter (200 micron) optical fiber and recorded on a fast streak camera at the output of 1 meter Czerny-Turner monochromator (F/7 optics). To calibrate such a system, it is necessary to efficiently couple light from a spectral lamp into a 200 micron diameter fiber, split it into its spectral components, with 10 Angstroms or less resolution, and record it on a streak camera with 1ns or less temporal resolution.

  7. Performances of a solid streak camera based on conventional CCD with nanosecond time resolution

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Bai, Yonglin; Zhu, Bingli; Gou, Yongsheng; Xu, Peng; Bai, XiaoHong; Liu, Baiyu; Qin, Junjun

    2015-02-01

    Imaging systems with high temporal resolution are needed to study rapid physical phenomena ranging from shock waves, including extracorporeal shock waves used for surgery, to diagnostics of laser fusion and fuel injection in internal combustion engines. However, conventional streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. Here we report an CMOS streak camera project consists in reproducing completely this streak camera functionality with a single CMOS chip. By changing the mode of charge transfer of CMOS image sensor, fast photoelectric diagnostics of single point with linear CMOS and high-speed line scanning with array CMOS sensor can be achieved respectively. A fast photoelectric diagnostics system has been designed and fabricated to investigate the feasibility of this method. Finally, the dynamic operation of the sensors is exposed. Measurements show a sample time of 500 ps and a time resolution better than 2 ns.

  8. Effects of elevated [CO2] on maize defence against mycotoxigenic Fusarium verticillioides

    PubMed Central

    Vaughan, Martha M; Huffaker, Alisa; Schmelz, Eric A; Dafoe, Nicole J; Christensen, Shawn; Sims, James; Martins, Vitor F; Swerbilow, Jay; Romero, Maritza; Alborn, Hans T; Allen, Leon HARTWELL; Teal, Peter EA

    2014-01-01

    Maize is by quantity the most important C4 cereal crop; however, future climate changes are expected to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce productivity. While rising atmospheric [CO2] is a driving force behind the warmer temperatures and drought, which aggravate fungal disease and mycotoxin accumulation, our understanding of how elevated [CO2] will effect maize defences against such pathogens is limited. Here we report that elevated [CO2] increases maize susceptibility to Fusarium verticillioides proliferation, while mycotoxin levels are unaltered. Fumonisin production is not proportional to the increase in F. verticillioides biomass, and the amount of fumonisin produced per unit pathogen is reduced at elevated [CO2]. Following F. verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones and downstream phytoalexins is dampened in maize grown at elevated [CO2]. The attenuation of maize 13-LOXs and jasmonic acid production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2]. Our findings suggest that elevated [CO2] will compromise maize LOX-dependent signalling, which will influence the interactions between maize and mycotoxigenic fungi. Elevated [CO2] increases maize susceptibility to Fusarium verticillioides proliferation but mycotoxin levels are unaltered. The attenuation of maize 13-LOXs and JA production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2]. PMID:24689748

  9. Complete genome sequence of nine isolates of canna yellow streak virus reveals its relationship to the sugarcane mosaic virus (SCMV) subgroup of potyviruses.

    PubMed

    Chauhan, Ravendra P; Rajakaruna, Punsasi; Verchot, Jeanmarie

    2015-03-01

    Complete genome sequences were obtained from nine isolates of canna yellow streak virus (CaYSV). CaYSV belongs to the sugarcane mosaic virus (SCMV) subgroup of potyviruses with johnsongrass mosaic virus (JGMV) as its closest relative. Multiple sequence alignments showed a pattern of amino acid substitutions in the CP sequences, which enabled us to relate these isolates to South East Asian or European isolates. Biological characterization of CaYSV identified Nicotiana benthamiana, Chenopodium quinoa and Phaseolus vulgaris as experimental hosts. Given the popularity and global trade of cannas, a clear picture of the genetic diversity of CaYSV is critical to disease management. PMID:25567205

  10. Development of a multiplexed PCR detection method for Barley and Cereal Yellow Dwarf Viruses, Wheat Spindle Streak Virus, Wheat Streak Mosaic Virus and Soil-Borne Wheat Mosaic Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley and Cereal Yellow Dwarf Viruses (B/CYDVs), Wheat Spindle Streak Mosaic (WSSMV), Soil-Borne Wheat Mosaic (SBWMV) Mosaic Virus and Wheat Streak Mosaic Virus (WSMV) constitute the most economically important group of wheat viruses. In this paper, a multiplex reverse transcription polymerase chai...

  11. System for photometric calibration of optoelectronic imaging devices especially streak cameras

    DOEpatents

    Boni, Robert; Jaanimagi, Paul

    2003-11-04

    A system for the photometric calibration of streak cameras and similar imaging devices provides a precise knowledge of the camera's flat-field response as well as a mapping of the geometric distortions. The system provides the flat-field response, representing the spatial variations in the sensitivity of the recorded output, with a signal-to-noise ratio (SNR) greater than can be achieved in a single submicrosecond streak record. The measurement of the flat-field response is carried out by illuminating the input slit of the streak camera with a signal that is uniform in space and constant in time. This signal is generated by passing a continuous wave source through an optical homogenizer made up of a light pipe or pipes in which the illumination typically makes several bounces before exiting as a spatially uniform source field. The rectangular cross-section of the homogenizer is matched to the usable photocathode area of the streak tube. The flat-field data set is obtained by using a slow streak ramp that may have a period from one millisecond (ms) to ten seconds (s), but may be nominally one second in duration. The system also provides a mapping of the geometric distortions, by spatially and temporarily modulating the output of the homogenizer and obtaining a data set using the slow streak ramps. All data sets are acquired using a CCD camera and stored on a computer, which is used to calculate all relevant corrections to the signal data sets. The signal and flat-field data sets are both corrected for geometric distortions prior to applying the flat-field correction. Absolute photometric calibration is obtained by measuring the output fluence of the homogenizer with a "standard-traceable" meter and relating that to the CCD pixel values for a self-corrected flat-field data set.

  12. Many maize genes are expressed in an oat background carrying a specific maize chromosome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oat-maize addition (OMA) lines are derived from oat x maize sexual hybrids in which individual maize chromosomes have been retained in plants containing a full complement of oat chromosomes. Many of the OMA lines display specific phenotypes, which indicate that maize genes are likely expressed and c...

  13. A grazing incidence x-ray streak camera for ultrafast, single-shot measurements

    SciTech Connect

    Feng, Jun; Engelhorn, K.; Cho, B.I.; Lee, H.J.; Greaves, M.; Weber, C.P.; Falcone, R.W.; Padmore, H. A.; Heimann, P.A.

    2010-02-18

    An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20 degree and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600fs temporal resolution, and 6mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo non-reversible changes.

  14. Linear stability of optimal streaks in the log-layer of turbulent channel flows

    NASA Astrophysics Data System (ADS)

    Alizard, Frédéric

    2015-10-01

    The importance of secondary instability of streaks for the generation of vortical structures attached to the wall in the logarithmic region of turbulent channels is studied. The streaks and their linear instability are computed by solving equations associated with the organized motion that include an eddy-viscosity modeling the effect of incoherent fluctuations. Three friction Reynolds numbers, Reτ = 2000, 3000, and 5000, are investigated. For all flow cases, optimal streamwise vortices (i.e., having the highest potential for linear transient energy amplification) are used as initial conditions. Due to the lift-up mechanism, these optimal perturbations lead to the nonlinear growth of streaks. Based on a Floquet theory along the spanwise direction, we observe the onset of streak secondary instability for a wide range of spanwise wavelengths when the streak amplitude exceeds a critical value. Under neutral conditions, it is shown that streak instability modes have their energy mainly concentrated in the overlap layer and propagate with a phase velocity equal to the mean streamwise velocity of the log-layer. These neutral log-layer modes exhibit a sinuous pattern and have characteristic sizes that are proportional to the wall distance in both streamwise and spanwise directions, in agreement with the Townsend's attached eddy hypothesis (A. Townsend, the structure of turbulent shear flow, Cambridge university press, 1976 2nd edition). In particular, for a distance from the wall varying from y+ ≈ 100 (in wall units) to y ≈ 0.3h, where h is half the height of the channel, the neutral log-layer modes are self-similar with a spanwise width of λz ≈ y/0.3 and a streamwise length of λx ≈ 3λz, independently of the Reynolds number. Based on this observation, it is suggested that compact vortical structures attached to the wall can be ascribed to streak secondary instabilities. In addition, spatial distributions of fluctuating vorticity components show that the onset

  15. 78 FR 24199 - Streak Products, Inc. v. UTi, United States, Inc.; Notice of Filing of Complaint and Assignment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-24

    ... Streak Products, Inc. v. UTi, United States, Inc.; Notice of Filing of Complaint and Assignment Notice is... Products, Inc. (``Streak''), hereinafter ``Complainant,'' against UTi, United States, Inc. (``UTi...). Complainant also alleges that ``UTi engaged in an unfair or unjustly discriminatory practice in violation...

  16. Isotopic streaks suggest a stripy plume under the Marquesas

    NASA Astrophysics Data System (ADS)

    Chauvel, C.; Blais, S.; Maury, R.; Lewin, E.

    2009-12-01

    underlying the southern and the northern islands is the same. We believe that the stripes are mantle plume characteristics. Their presence and persistent occurrence for the 5 Ma of Marquesas volcanism suggest that isotopically distinct mantle sources cohabitate but do not mix at distances less than 100 km. Furthermore, the isotopic range observed at the island scale is also very large, suggesting melting of extremely heterogeneous plume material. To account for all these observations, as well as the geophysical constraints and the age distribution of the islands, we suggest a model like that of Davaille (Nature, 1999) for general plume structures, and Farnetani and Hofmann (EPSL, 2009) for the internal structure of the Hawaiian plume: several small conduits that originated in a single deep mantle plume bring magma to the surface at different locations at the same time. The material melting in the plume is highly heterogeneous at all scales (10 to 100 km) but because systematic trends occur, an organized pattern must persist through time. The inference is that the heterogeneities in the plume were streaked out vertically and parallel to the direction of plume ascent.

  17. Inbreeding drives maize centromere evolution

    PubMed Central

    Schneider, Kevin L.; Xie, Zidian; Wolfgruber, Thomas K.; Presting, Gernot G.

    2016-01-01

    Functional centromeres, the chromosomal sites of spindle attachment during cell division, are marked epigenetically by the centromere-specific histone H3 variant cenH3 and typically contain long stretches of centromere-specific tandem DNA repeats (∼1.8 Mb in maize). In 23 inbreds of domesticated maize chosen to represent the genetic diversity of maize germplasm, partial or nearly complete loss of the tandem DNA repeat CentC precedes 57 independent cenH3 relocation events that result in neocentromere formation. Chromosomal regions with newly acquired cenH3 are colonized by the centromere-specific retrotransposon CR2 at a rate that would result in centromere-sized CR2 clusters in 20,000–95,000 y. Three lines of evidence indicate that CentC loss is linked to inbreeding, including (i) CEN10 of temperate lineages, presumed to have experienced a genetic bottleneck, contain less CentC than their tropical relatives; (ii) strong selection for centromere-linked genes in domesticated maize reduced diversity at seven of the ten maize centromeres to only one or two postdomestication haplotypes; and (iii) the centromere with the largest number of haplotypes in domesticated maize (CEN7) has the highest CentC levels in nearly all domesticated lines. Rare recombinations introduced one (CEN2) or more (CEN5) alternate CEN haplotypes while retaining a single haplotype at domestication loci linked to these centromeres. Taken together, this evidence strongly suggests that inbreeding, favored by postdomestication selection for centromere-linked genes affecting key domestication or agricultural traits, drives replacement of the tandem centromere repeats in maize and other crop plants. Similar forces may act during speciation in natural systems. PMID:26858403

  18. Inbreeding drives maize centromere evolution.

    PubMed

    Schneider, Kevin L; Xie, Zidian; Wolfgruber, Thomas K; Presting, Gernot G

    2016-02-23

    Functional centromeres, the chromosomal sites of spindle attachment during cell division, are marked epigenetically by the centromere-specific histone H3 variant cenH3 and typically contain long stretches of centromere-specific tandem DNA repeats (∼1.8 Mb in maize). In 23 inbreds of domesticated maize chosen to represent the genetic diversity of maize germplasm, partial or nearly complete loss of the tandem DNA repeat CentC precedes 57 independent cenH3 relocation events that result in neocentromere formation. Chromosomal regions with newly acquired cenH3 are colonized by the centromere-specific retrotransposon CR2 at a rate that would result in centromere-sized CR2 clusters in 20,000-95,000 y. Three lines of evidence indicate that CentC loss is linked to inbreeding, including (i) CEN10 of temperate lineages, presumed to have experienced a genetic bottleneck, contain less CentC than their tropical relatives; (ii) strong selection for centromere-linked genes in domesticated maize reduced diversity at seven of the ten maize centromeres to only one or two postdomestication haplotypes; and (iii) the centromere with the largest number of haplotypes in domesticated maize (CEN7) has the highest CentC levels in nearly all domesticated lines. Rare recombinations introduced one (CEN2) or more (CEN5) alternate CEN haplotypes while retaining a single haplotype at domestication loci linked to these centromeres. Taken together, this evidence strongly suggests that inbreeding, favored by postdomestication selection for centromere-linked genes affecting key domestication or agricultural traits, drives replacement of the tandem centromere repeats in maize and other crop plants. Similar forces may act during speciation in natural systems. PMID:26858403

  19. Numerical analysis of three-dimensional unsteady hot streak migration and shock interaction in a turbine stage

    SciTech Connect

    Saxer, A.P.; Felici, H.M.

    1996-04-01

    A three-dimensional unsteady flow computation has been performed for a transonic first turbine stage under the influence of streaks of hot gas exiting the combustion chamber. Realistic flow conditions are obtained by using an unequal stator-to-rotor pitch, a single-streak/multistator channel configuration, and periodic boundary conditions. The resulting unsteady shock wave system and the hot streak migration as well as the shock wave/streak interaction are presented and discussed. In addition, the time average of the periodic unsteady solution is analyzed and compared with a steady-state computation. The steady-state solution matches the time-averaged one in terms of the pressure field and the maximum stagnation temperature on the rotor blade surface. However, the rotor blade temperature patterns are different with a stronger radial secondary flow present in the time-averaged solution due to the retention of the circumferential streak variations at the stator/rotor interface.

  20. MaizeGDB's New Genome Browser Project

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB (http://www.maizegdb.org) is the community database for maize genetics and genomics. Based upon the 2006 MaizeGDB Working Group Report (available at http://www.maizegdb.org/working_group.php) and the Allerton Report (http://www.maizegdb.org/AllertonReport.doc), it has become evident that th...

  1. The MaizeGDB Genome Browser

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB (http://www.maizegdb.org) is the community database for maize genetics and genomics. As part of a larger effort to develop MaizeGDB into a more sequence-centric resource, we recently implemented a genome browser. The GBrowse platform was chosen for this endeavor based on results of a survey...

  2. MaizeGDB: New tools and resource

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB, the USDA-ARS genetics and genomics database, is a highly curated, community-oriented informatics service to researchers focused on the crop plant and model organism Zea mays. MaizeGDB facilitates maize research by curating, integrating, and maintaining a database that serves as the central...

  3. The Genetic Architecture of Maize Flowering Time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flowering time is the key trait controlling adaptation of plants to their local environment, and, in an outcrossing species like maize, it is a complex trait. Variation for this complex trait was dissected in maize using a novel set of 5000 recombinant inbred lines (maize Nested Association Mapping...

  4. MaizeGDB Becomes Sequence-centric

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the maize research community’s central repository for genetic and genomic information about the crop plant and research model Zea mays ssp. mays. The MaizeGDB team endeavors to meet research needs as they evolve based on researcher feedback and guidance. Recent work has focused on bett...

  5. Maize, tropical (Zea mays L.).

    PubMed

    Assem, Shireen K

    2015-01-01

    Maize (Zea mays L.) is the third most important food crop globally after wheat and rice. In sub-Saharan Africa, tropical maize has traditionally been the main staple of the diet; 95 % of the maize grown is consumed directly as human food and as an important source of income for the resource-poor rural population. The biotechnological approach to engineer biotic and abiotic traits implies the availability of an efficient plant transformation method. The production of genetically transformed plants depends both on the ability to integrate foreign genes into target cells and the efficiency with which plants are regenerated. Maize transformation and regeneration through immature embryo culture is the most efficient system to regenerate normal transgenic plants. However, this system is highly genotype dependent. Genotypes adapted to tropic areas are difficult to regenerate. Therefore, transformation methods used with model genotypes adapted to temperate areas are not necessarily efficient with tropical lines. Agrobacterium-mediated transformation is the method of choice since it has been first achieved in 1996. In this report, we describe a transformation method used successfully with several tropical maize lines. All the steps of transformation and regeneration are described in details. This protocol can be used with a wide variety of tropical lines. However, some modifications may be needed with recalcitrant lines. PMID:25300835

  6. Optical Comb Generation for Streak Camera Calibration for Inertial Confinement Fusion Experiments

    SciTech Connect

    Ronald Justin, Terence Davies, Frans Janson, Bruce Marshall, Perry Bell, Daniel Kalantar, Joseph Kimbrough, Stephen Vernon, Oliver Sweningsen

    2008-09-18

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is coming on-line to support physics experimentation for the U.S. Department of Energy (DOE) programs in Inertial Confinement Fusion (ICF) and Stockpile Stewardship (SS). Optical streak cameras are an integral part of the experimental diagnostics instrumentation at NIF. To accurately reduce streak camera data a highly accurate temporal calibration is required. This article describes a technique for simultaneously generating a precise +/- 2 ps optical marker pulse (fiducial reference) and trains of precisely timed, short-duration optical pulses (so-called “comb” pulse trains) that are suitable for the timing calibrations. These optical pulse generators are used with the LLNL optical streak cameras. They are small, portable light sources that, in the comb mode, produce a series of temporally short, uniformly spaced optical pulses, using a laser diode source. Comb generators have been produced with pulse-train repetition rates up to 10 GHz at 780 nm, and somewhat lower frequencies at 664 nm. Individual pulses can be as short as 25-ps FWHM. Signal output is via a fiber-optic connector on the front panel of the generator box. The optical signal is transported from comb generator to streak camera through multi-mode, graded-index optical fiber.

  7. Physiological responses of hard red winter wheat to infection by wheat streak mosaic virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat streak mosaic virus (WSMV) causes significant yield loss in hard red winter wheat in the U.S. Southern High Plains. Despite the prevalence of this pathogen, little is known about the physiological response of wheat to WSMV infection. A 2-year study was initiated to (i) investigate the effect o...

  8. Economic impact of wheat streak mosaic virus in the Texas High Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite Aceria tosichella Keifer, is a major limiting factor in wheat production in the Texas Panhandle. It is the most frequently encountered virus in the region, affecting both shoot and root biomass, and consequently it can drastically red...

  9. Multiplex Real Time PCR For Detection of Wheat Streak Mosaic Virus and Triticum Mosaic Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TRIMV) are widespread throughout the southwestern Great Plains states. Using conventional diagnostics such as Enzyme-Linked Immunosorbent Assays (ELISA), these two viruses are commonly found together in infected wheat samples. Methods for m...

  10. Complete genome sequence of an emerging genotype of tobacco streak virus in the U.S.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the complete genome sequence of an emerging genotype of Tobacco streak virus (TSV) infecting zucchini squash in Florida (TSV_FL13-07), through deep sequencing of sRNAs and validation by Sanger sequencing. TSV_FL13-07 only shares less than 90% sequence identity in three genomic ribonucleic...

  11. Pedicle streaking: A novel and simple aid in pedicle positioning in free tissue transfer

    PubMed Central

    Aggarwal, Aditya; Singh, Hardeep; Mahendru, Sanjay; Brajesh, Vimalendu; Singh, Sukhdeep; Khare, Ashish; Kothari, Umang; Khazanchi, Rakesh Kumar

    2015-01-01

    Introduction: The pedicle positioning in free tissue transfer is critical to its success. Long thin pedicles are especially prone to this complication where even a slight twist in the perforator can result in flap loss. Pedicles passing through the long tunnels are similarly at risk. Streaking the pedicle with methylene blue is a simple and safe method which increases the safety of free tissue transfer. Materials and Methods: Once the flap is islanded on the pedicle and the vascularity of the flap is confirmed, the pedicle is streaked with methylene blue dye at a distance of 6-7 mm. The streaking starts from the origin of the vessels and continued distally on to the under surface of flap to mark the complete course of the pedicle in alignment. The presence of streaking in some parts and not in rest indicates twist in the pedicle. Observation and Results: Four hundred and sixty five free flaps have been done at our centre in the last 5 years. The overall success rate of free flaps is 95.3% (22 free flap failures). There has not been a single case of pedicle twist leading to flap congestion and failure. Conclusion: This simple and novel method is very reliable for pedicle positioning avoiding any twist necessary for successful free tissue transfer. PMID:26933280

  12. Simultaneous velocity interferometry and electronic streak photography of laser-launched plates

    SciTech Connect

    Paisley, D.L.; Stahl, D.B.; Garcia, I.A.

    1991-01-01

    Laser-launched, miniature, pseudo-one-dimensional flyer plates are evaluated by three distinct optical techniques that may be incorporated into an optical diagnostic system to give a complete understanding of the plate performance. These techniques are: velocity interferometry, streak photography, and pulsed laser stereo photography. 2 refs., 5 figs.

  13. Standard design for National Ignition Facility x-ray streak and framing cameras.

    PubMed

    Kimbrough, J R; Bell, P M; Bradley, D K; Holder, J P; Kalantar, D K; MacPhee, A G; Telford, S

    2010-10-01

    The x-ray streak camera and x-ray framing camera for the National Ignition Facility were redesigned to improve electromagnetic pulse hardening, protect high voltage circuits from pressure transients, and maximize the use of common parts and operational software. Both instruments use the same PC104 based controller, interface, power supply, charge coupled device camera, protective hermetically sealed housing, and mechanical interfaces. Communication is over fiber optics with identical facility hardware for both instruments. Each has three triggers that can be either fiber optic or coax. High voltage protection consists of a vacuum sensor to enable the high voltage and pulsed microchannel plate phosphor voltage. In the streak camera, the high voltage is removed after the sweep. Both rely on the hardened aluminum box and a custom power supply to reduce electromagnetic pulse/electromagnetic interference (EMP/EMI) getting into the electronics. In addition, the streak camera has an EMP/EMI shield enclosing the front of the streak tube. PMID:21034058

  14. Diverse soybean accessions identified with temperature-sensitive resistance to Tobacco streak virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tobacco streak virus (TSV) is a pathogen that has been reported in soybean in Brazil and the United States, for which resistance has only been reported in the “hay-type” soybean cultivar Tanner. To find additional resistant soybean genotypes, over 1000 soybean accessions from the USDA Soybean Germpl...

  15. Laboratory Simulations and Spectral Analyses of Recurring Slope Streaks on Mars

    NASA Astrophysics Data System (ADS)

    Wing, B.; Irvin, B.; Hibbitts, C.; Mushkin, A.

    2014-12-01

    Low albedo streaks on Martian slopes have been cited as possible evidence for present-day intermittent and repeated surface flow of water, or brine (Mushkin et al., 2010). Also termed as Recurring Slope Lineae (1), such streaks can grow, fade, and recur repeatedly on the same slopes. Although distinguishable by being darker than surrounding terrain slope streaks have no diagnostic spectral absorption features (2). A leading hypothesis is formation by multiple wetting and drying events. Laboratory investigations have previously explored this possibility (e.g 3). When wetted with brines, soils darken, but as the sample dries, it brightens again. Wetting also results in absorption bands near 1.5 and 2 microns, which are not detected in spectra of slope streaks. Additionally, dried brines of most salts such as MgSO4, or other sulfates and many chlorides are brighter than Martian soils. However, iron chlorides are a salt that have lower albedo than most other salts and may present a mechanism for darkening slope streaks without inducing a spectral absorption feature. To explore this hypothesis, we have begun to conduct experiments investigating the spectra of iron chloride chloride solutions wetting palagonite and subsequently drying under Martian atmospheric conditions. Preliminary experiments demonstrate that FeIII chloride dried onto palagonite has no absorption features in the NIR and SWIR and remains dark and red. However, these chlorides will oxidize under terrestrial conditions forming Fe2O3 as they dry. We have constructed an environmental chamber that mimics Martian oxygen fugacity though a combination of vacuum and N2 purging, allowing for sample wetting and drying while concurrently taking spectra from 0.4 to 2.4 microns. Results from this experimental setup under Martian atmospheric conditions will be presented. References: (1) McEwen et al., (2011) Science, 333, 740-743, (2) Mushkin et al., (2010) Geophys. Res. Lett., 37, L22201, doi: 10.1029/2010GL044535

  16. MaizeGDB update: new tools, data and interface for the maize model organism database

    PubMed Central

    Andorf, Carson M.; Cannon, Ethalinda K.; Portwood, John L.; Gardiner, Jack M.; Harper, Lisa C.; Schaeffer, Mary L.; Braun, Bremen L.; Campbell, Darwin A.; Vinnakota, Abhinav G.; Sribalusu, Venktanaga V.; Huerta, Miranda; Cho, Kyoung Tak; Wimalanathan, Kokulapalan; Richter, Jacqueline D.; Mauch, Emily D.; Rao, Bhavani S.; Birkett, Scott M.; Sen, Taner Z.; Lawrence-Dill, Carolyn J.

    2016-01-01

    MaizeGDB is a highly curated, community-oriented database and informatics service to researchers focused on the crop plant and model organism Zea mays ssp. mays. Although some form of the maize community database has existed over the last 25 years, there have only been two major releases. In 1991, the original maize genetics database MaizeDB was created. In 2003, the combined contents of MaizeDB and the sequence data from ZmDB were made accessible as a single resource named MaizeGDB. Over the next decade, MaizeGDB became more sequence driven while still maintaining traditional maize genetics datasets. This enabled the project to meet the continued growing and evolving needs of the maize research community, yet the interface and underlying infrastructure remained unchanged. In 2015, the MaizeGDB team completed a multi-year effort to update the MaizeGDB resource by reorganizing existing data, upgrading hardware and infrastructure, creating new tools, incorporating new data types (including diversity data, expression data, gene models, and metabolic pathways), and developing and deploying a modern interface. In addition to coordinating a data resource, the MaizeGDB team coordinates activities and provides technical support to the maize research community. MaizeGDB is accessible online at http://www.maizegdb.org. PMID:26432828

  17. MaizeGDB update: new tools, data and interface for the maize model organism database.

    PubMed

    Andorf, Carson M; Cannon, Ethalinda K; Portwood, John L; Gardiner, Jack M; Harper, Lisa C; Schaeffer, Mary L; Braun, Bremen L; Campbell, Darwin A; Vinnakota, Abhinav G; Sribalusu, Venktanaga V; Huerta, Miranda; Cho, Kyoung Tak; Wimalanathan, Kokulapalan; Richter, Jacqueline D; Mauch, Emily D; Rao, Bhavani S; Birkett, Scott M; Sen, Taner Z; Lawrence-Dill, Carolyn J

    2016-01-01

    MaizeGDB is a highly curated, community-oriented database and informatics service to researchers focused on the crop plant and model organism Zea mays ssp. mays. Although some form of the maize community database has existed over the last 25 years, there have only been two major releases. In 1991, the original maize genetics database MaizeDB was created. In 2003, the combined contents of MaizeDB and the sequence data from ZmDB were made accessible as a single resource named MaizeGDB. Over the next decade, MaizeGDB became more sequence driven while still maintaining traditional maize genetics datasets. This enabled the project to meet the continued growing and evolving needs of the maize research community, yet the interface and underlying infrastructure remained unchanged. In 2015, the MaizeGDB team completed a multi-year effort to update the MaizeGDB resource by reorganizing existing data, upgrading hardware and infrastructure, creating new tools, incorporating new data types (including diversity data, expression data, gene models, and metabolic pathways), and developing and deploying a modern interface. In addition to coordinating a data resource, the MaizeGDB team coordinates activities and provides technical support to the maize research community. MaizeGDB is accessible online at http://www.maizegdb.org. PMID:26432828

  18. Global maize production, utilization, and consumption.

    PubMed

    Ranum, Peter; Peña-Rosas, Juan Pablo; Garcia-Casal, Maria Nieves

    2014-04-01

    Maize (Zea mays), also called corn, is believed to have originated in central Mexico 7000 years ago from a wild grass, and Native Americans transformed maize into a better source of food. Maize contains approximately 72% starch, 10% protein, and 4% fat, supplying an energy density of 365 Kcal/100 g and is grown throughout the world, with the United States, China, and Brazil being the top three maize-producing countries in the world, producing approximately 563 of the 717 million metric tons/year. Maize can be processed into a variety of food and industrial products, including starch, sweeteners, oil, beverages, glue, industrial alcohol, and fuel ethanol. In the last 10 years, the use of maize for fuel production significantly increased, accounting for approximately 40% of the maize production in the United States. As the ethanol industry absorbs a larger share of the maize crop, higher prices for maize will intensify demand competition and could affect maize prices for animal and human consumption. Low production costs, along with the high consumption of maize flour and cornmeal, especially where micronutrient deficiencies are common public health problems, make this food staple an ideal food vehicle for fortification. PMID:24650320

  19. Investigations on Fusarium spp. and their mycotoxins causing Fusarium ear rot of maize in Kosovo.

    PubMed

    Shala-Mayrhofer, Vitore; Varga, Elisabeth; Marjakaj, Robert; Berthiller, Franz; Musolli, Agim; Berisha, Defrime; Kelmendi, Bakir; Lemmens, Marc

    2013-01-01

    After wheat, maize (Zea mays L.) is the second most important cereal crop in Kosovo and a major component of animal feed. The purpose of this study was to analyse the incidence and identity of the Fusarium species isolated from naturally infected maize kernels in Kosovo in 2009 and 2010, as well as the mycotoxin contamination. The disease incidence of Fusarium ear rot (from 0.7% to 40% diseased ears) on maize in Kosovo is high. The most frequently Fusarium spp. identified on maize kernels were Fusarium subglutinans, F. verticillioides/F. proliferatum and F. graminearum. Maize kernel samples were analysed by LC-MS/MS and found to be contaminated with deoxynivalenol (DON), DON-3-glucoside, 3-acetyl-DON, 15-acetyl-DON, zearalenone, zearalenone-14-sulphate, moniliformin, fumonisin B1 and fumonisin B2. This is the first report on the incidence and identification of Fusarium species isolated from naturally infected maize as well as the mycotoxin contamination in Kosovo. PMID:24779930

  20. Use of Mutant-Assisted Gene Identification and Characterization (MAGIC) to identify novel genetic loci that modify the maize hypersensitive response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The partially-dominant, autoactive maize disease resistance gene Rp1-D21 causes hypersensitive response (HR) lesions to form spontaneously on the leaves and stem in the absence of pathogen recognition. The maize nested association mapping (NAM) population consists of 25 200-line subpopulations each...

  1. A single extraction method for the analysis by liquid chromatography/tandem mass spectrometry of fumonisins and biomarkers of disrupted sphingolipid metabolism in tissues of maize seedlings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Fusarium verticillioides is a pathogen of many plants and produces fumonisins. In addition to their well-studied animal toxicoses these toxins contribute to the development of maize seedling disease in susceptible maize varieties. Fumonisin disruption of sphingolipid biosynthesis occurs ...

  2. Development of maize starch granules

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize kernels of self-pollinated inbred line B73 harvested on various days after pollination (DAP) were subjected for starch granule development studies. Starch in endosperms was first observed on 6 DAP. A small amount of starch granules (<2% of dry weight) was found in the endosperm on 12 DAP. S...

  3. Maize Genetics and Genomics Database

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The 2007 report for MaizeGDB lists the new hires who will focus on curation/outreach and the genome sequence, respectively. Currently all sequence in the database comes from a PlantGDB pipeline and is presented with deep links to external resources such as PlantGDB, Dana Farber, GenBank, the Arizona...

  4. Flowering and Determinacy in Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    All plant organs are produced by meristems, groups of stem cells located in the tips of roots and shoots. Indeterminate meristems make an indefinite number of organs, whereas determinate meristems are consumed after making a specific number of organs. Maize is an ideal system to study the genetic co...

  5. Betaine Deficiency in Maize 1

    PubMed Central

    Lerma, Claudia; Rich, Patrick J.; Ju, Grace C.; Yang, Wen-Ju; Hanson, Andrew D.; Rhodes, David

    1991-01-01

    Maize (Zea mays L.) is a betaine-accumulating species, but certain maize genotypes lack betaine almost completely; a single recessive gene has been implicated as the cause of this deficiency (D Rhodes, PJ Rich [1988] Plant Physiol 88: 102-108). This study was undertaken to determine whether betaine deficiency in diverse maize germplasm is conditioned by the same genetic locus, and to define the biochemical lesion(s) involved. Complementation tests indicated that all 13 deficient genotypes tested shared a common locus. One maize population (P77) was found to be segregating for betaine deficiency, and true breeding individuals were used to produce related lines with and without betaine. Leaf tissue of both betaine-positive and betaine-deficient lines readily converted supplied betaine aldehyde to betaine, but only the betaine-containing line was able to oxidize supplied choline to betaine. This locates the lesion in betaine-deficient plants at the choline → betaine aldehyde step of betaine synthesis. Consistent with this location, betaine-deficient plants were shown to have no detectable endogenous pool of betaine aldehyde. PMID:16668098

  6. Evaluation of nitric oxide detoxifying flavohaemoglobin in the Fusarium verticillioides – maize interaction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium verticillioides is a non-obligate pathogen causing a number of maize diseases. Apart from these diseases, F. verticillioides is also known to asymptomatically infect most tissues of the plant. The production of the mycotoxin fumonisin B1 by F. verticillioides and other complexities of the i...

  7. Enantioselective Phytotoxicity of Imazamox Against Maize Seedlings.

    PubMed

    Wei, Jing; Zhang, Xiaoxiao; Li, Xuesheng; Zeng, Dongqiang; Tan, Huihua

    2016-02-01

    There is increasing concern about the enantioselective effects of chiral herbicides. To study the enantioselective toxicity of the chiral herbicide imazamox on maize, maize seedlings (Zhengda 619, Zea mays L.) were exposed to imazamox racemate and enantiomers in hydroponic experiments. The results showed that imazamox enantiomers selectively affected maize. The effective concentration of Rac-, S- and R-imazamox that caused 50 % inhibition after 5 days treatments (EC50,5d) were 0.4212, 1.2142 and 0.2460 mg L(-1), respectively, for maize root length; 0.0002, 0.1005, 0.0032 mg L(-1), respectively, for maize root fresh weight; 0.7114, 1.4056 and 0.4530 mg L(-1), respectively, for maize shoot height; 0.6220, 1.5418, 0.2286 mg L(-1), respectively, for maize shoot fresh weight; and 0.1100, 0.3306, 0.0307 mg L(-1), respectively, for the total chlorophyll content of leaves. The root morphological parameters and root activity reflected the toxicity effects in the order R-imazamox > Rac-imazamox > S-imazamox. Maize roots were more sensitive to imazamox than maize shoots. The chiral herbicide imazamox poses enantioselective phytotoxicity on maize seedlings: the order of toxicity is R-imazamox > Rac-imazamox > S-imazamox. PMID:26508428

  8. Genomic variability and molecular evolution of Asian isolates of sugarcane streak mosaic virus.

    PubMed

    Liang, Shan-Shan; Alabi, Olufemi J; Damaj, Mona B; Fu, Wei-Lin; Sun, Sheng-Ren; Fu, Hua-Ying; Chen, Ru-Kai; Mirkov, T Erik; Gao, San-Ji

    2016-06-01

    Sugarcane streak mosaic virus (SCSMV), an economically important causal agent of mosaic disease of sugarcane, is a member of the newly created genus Poacevirus in the family Potyviridae. In this study, we report the molecular characterization of three new SCSMV isolates from China (YN-YZ211 and HN-YZ49) and Myanmar (MYA-Formosa) and their genetic variation and phylogenetic relationship to SCSMV isolates from Asia and the type members of the family Potyviridae. The complete genome of each of the three isolates was determined to be 9781 nucleotides (nt) in size, excluding the 3' poly(A) tail. Phylogenetic analysis of the complete polyprotein amino acid (aa) sequences (3130 aa) revealed that all SCSMV isolates clustered into a phylogroup specific to the genus Poacevirus and formed two distinct clades designated as group I and group II. Isolates YN-YZ211, HN-YZ49 and MYA-Formosa clustered into group I, sharing 96.8-99.5 % and 98.9-99.6 % nt (at the complete genomic level) and aa (at the polyprotein level) identity, respectively, among themselves and 81.2-98.8 % and 94.0-99.6 % nt (at the complete genomic level) and aa (at the polyprotein level) identity, respectively, with the corresponding sequences of seven Asian SCSMV isolates. Population genetic analysis revealed greater between-group (0.190 ± 0.004) than within-group (group I = 0.025 ± 0.001 and group II = 0.071 ± 0.003) evolutionary divergence values, further supporting the results of the phylogenetic analysis. Further analysis indicated that natural selection might have contributed to the evolution of isolates belonging to the two identified SCSMV clades, with infrequent genetic exchanges occurring between them over time. These findings provide a comprehensive analysis of the population genetic structure and driving forces for the evolution of SCSMV with implications for global exchange of sugarcane germplasm. PMID:26973230

  9. Angioid Streaks in Types I and II Congenital Dyserythropoietic Anaemia (CDA).

    PubMed

    Frimmel, S; Kniestedt, C

    2016-04-01

    Background. Angioid streaks (AS) are visible irregular breaks in Bruch's membrane, extending radially from the optic nerve head and with overlaying atrophic retinal pigment epithelium. In 50 % of patients, AS are associated with Pseudoxanthoma elasticum, Ehlers-Danlos syndrome, sickle cell anaemia or Paget's disease. In 50 % of patients, AS are idiopathic. Congenital Dyserythropoietic Anaemia (CDA) is a rare, inherited disorder of ineffective erythropoiesis with morphologically abnormal erythroblasts. CDA was first recognised as a separate entity in 1968 and classified into three main groups. CDA demographics have identified 614 known families and > 700 cases worldwide. A few case reports of AS in CDA I and III have been published, but there is no report of AS in CDA II, the most frequent of the CDAs, as well no follow-up. History and Signs. 8 eyes of 4 CDA patients were examined. The CDA I patients were a 46 year old man and a 52 year old woman. They were first seen in 2009 and followed up for 9 and 11 months, respectively. The 2 female CDA II patients were seen in 2010 and were aged 35 and 42 years at first presentation. Vision, Amsler grid, optical coherence tomography (OCT), fundus pictures and fluorescent angiography were performed. Blood was drawn for neutrophil elastase determination (ELA2). Therapy and Outcome. All patients showed bilateral AS. Mean best corrected visual acuity was 20/20 without metamorphopsia and with normal OCT. During the follow-up period, no progression occurred. No choroidal neovascularisation (CNV) was detected. ELA2 serum levels were normal. Conclusions. This is the first report of AS in CDA II and the first follow-up in CDA I. No evidence of progression was seen within this period of time. Longer follow-up is needed to detect whether AS progresses. All patients with AS should be seen by an ophthalmologist on a regular basis. The risk of CNV is given. Therapy is possible and the outcome is best if the CNV is recognised and

  10. Optical streak camera images of wire-array z-pinches on the 1-MA COBRA pulsed power generator

    NASA Astrophysics Data System (ADS)

    McBride, Ryan; Pikuz, Sergei; Blesener, Isaac; Zhao, Yu Tao; Greenly, John; Hammer, David; Kusse, Bruce

    2006-10-01

    Initial optical streak camera imaging experiments of wire array z-pinches on the 1 MA COBRA pulsed power generator are presented. The imaging system makes use of a Hamamatsu C7700 streak unit, which is coupled to a V7669-06 image intensifier with an MCP, and a C4742-98 CCD camera. A long focal length optical system is employed to relay the z-pinch produced light from the experiment chamber to the input slit of the streak camera -- a total transmission distance of approximately 14 m. The optical streak camera images produced, along with data from other supporting diagnostics, are presented for z-pinch implosions of various wire array geometries and materials.

  11. Initial tests of the dual-sweep streak camera system planned for APS particle-beam diagnostics

    SciTech Connect

    Lumpkin, A.; Yang, B.; Gai, W.; Cieslik, W.

    1995-07-01

    Initial tests of a dual-sweep streak system planned for use on the Advanced Photon Source (APS) have been performed using assets of the Argonne Wakefield Accelerator (AWA) facility. The short light pulses from the photoelectric injector drive laser in both the visible ({lambda}=496 nm, {Delta}t{approximately}1.5 ps (FWHM)), and the ultraviolet ({lambda}=248 nm, {Delta}t{approximately}5 ps (FWHM)) were used. Both a UV-visible S20 photocathode streak tube and a UV-to-x-ray Au photocathode streak tube were tested. Calibration data with an etalon were also obtained. A sample of dual-sweep streak data using optical synchrotron radiation on the APS injector synchrotron is also presented.

  12. Streaked radiography of an irradiated foam sample on the National Ignition Facility

    SciTech Connect

    Cooper, A. B. R.; Schneider, M. B.; MacLaren, S. A.; Young, P. E.; Hsing, W. W.; Seugling, R.; Foord, M. E.; Sain, J. D.; May, M. J.; Marrs, R. E.; Maddox, B. R.; Lu, K.; Dodson, K.; Smalyuk, V.; Moore, A. S.; Graham, P.; Foster, J. M.; Back, C. A.; Hund, J. F.

    2013-03-15

    Streaked x-ray radiography images of annular patterns in an evolving tantalum oxide foam under the influence of a driven, subsonic radiation wave were obtained on the National Ignition Facility. This is the first successful radiography measurement of the evolution of well-defined foam features under a driven, subsonic wave in the diffusive regime. A continuous record of the evolution was recorded on an x-ray streak camera, using a slot-apertured point-projection backlighter with an 8 ns nickel source (7.9 keV). Radiography images were obtained for four different annular patterns, which were corrected using a source-dependent flat-field image. The evolution of the foam features was well-modeled using the 3D KULL radiation hydrodynamics code. This experimental and modeling platform can be modified for scaled high-energy-density laboratory astrophysics experiments.

  13. Effects of diabatic heating on the ageostrophic circulation of an upper tropospheric jet streak

    NASA Technical Reports Server (NTRS)

    Keyser, D. A.; Johnson, D. R.

    1982-01-01

    Interaction between the mass circulation within a mesoscale convective complex (MCC) and a direct mass circulation in the entrance region of an upper tropospheric polar jet streak was examined within the isentropic structure to investigate mechanisms responsible for linking these two scales of motion. The results establish that latent heating in the MCC modifies the direct mass circulation in the jet streak entrance region through the diabatically induced components of ageostrophic motion analyzed within isentropic coordinates. Within the strong mesoscale mass circulation of each MCC, strong horizontal mass flux convergence into the MCC at low levels is balanced by strong horizontal mass flux divergence away from the convergence at upper levels. Locations of large diabatic heating rates correspond well to the MCC position for each case; diabatic heating forces the upward vertical branch for the mesoscale mass circulation.

  14. A distinct tospovirus causing necrotic streak on Alstroemeria sp. in Colombia.

    PubMed

    Hassani-Mehraban, Afshin; Botermans, Marleen; Verhoeven, J Th J; Meekes, Ellis; Saaijer, Janneke; Peters, Dick; Goldbach, Rob; Kormelink, Richard

    2010-03-01

    A tospovirus causing necrotic streaks on leaves was isolated from Alstroemeria sp. in Colombia. Infected samples reacted positively with tomato spotted wilt virus (TSWV) antiserum during preliminary serological tests. Further analysis revealed a close serological relationship to tomato chlorotic spot virus (TCSV) and groundnut ringspot virus (GRSV). A major part of the S-RNA segment, encompassing the nucleocapsid (N) protein gene, the 5' untranslated region and a part of the intergenic region 3' of the N gene, was cloned and sequenced. The deduced N protein sequence showed highest amino acid identity (82%) to that of TCSV, indicating that the virus represents a new tospovirus species, for which the name Alstroemeria necrotic streak virus (ANSV) is coined. Phylogenetic analysis based on the N protein sequence revealed that this Alstroemeria-infecting tospovirus clustered with tospoviruses from the American continent. Frankliniella occidentalis was identified as potential vector species for ANSV. PMID:20151164

  15. Time-Resolved Spectra of Dense Plasma Focus Using Spectrometer, Streak Camera, CCD Combination

    SciTech Connect

    F. J. Goldin, B. T. Meehan, E. C. Hagen, P. R. Wilkins

    2010-10-01

    A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny–Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

  16. Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination

    SciTech Connect

    Goldin, F. J.; Meehan, B. T.; Hagen, E. C.; Wilkins, P. R.

    2010-10-15

    A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

  17. Protocol for observing molecular dipole excitations by attosecond self-streaking

    NASA Astrophysics Data System (ADS)

    Wachter, Georg; Nagele, Stefan; Sato, Shunsuke A.; Pazourek, Renate; Wais, Michael; Lemell, Christoph; Tong, Xiao-Min; Yabana, Kazuhiro; Burgdörfer, Joachim

    2015-12-01

    We propose a protocol to probe the ultrafast evolution and dephasing of coherent electronic excitation in molecules in the time domain by the intrinsic streaking field generated by the molecule itself. Coherent electronic motion in the endohedral fullerene Ne@C 60 is initiated by a moderately intense femtosecond UV-visible pulse leading to coherent oscillations of the molecular dipole moment that persist after the end of the laser pulse. The resulting time-dependent molecular near field is probed through the momentum modulation of photoemission from the central neon atom by a time-delayed attosecond XUV pulse. Our ab initio time-dependent density functional theory and classical trajectory simulations predict that this self-streaking signal accurately traces the molecular dipole oscillations in real time. We discuss the underlying processes and give an analytical model that captures the essence of our ab initio simulations.

  18. Extra-embryonic Wnt3 regulates the establishment of the primitive streak in mice

    PubMed Central

    Yoon, Yeonsoo; Huang, Tingting; Tortelote, Giovane G.; Wakamiya, Maki; Hadjantonakis, Anna-Katerina; Behringer, Richard R.; Rivera-Pérez, Jaime A.

    2015-01-01

    The establishment of the head to tail axis at early stages of development is a fundamental aspect of vertebrate embryogenesis. In mice, experimental embryology, genetics and expression studies have suggested that the visceral endoderm, an extra-embryonic tissue, plays an important role in anteroposterior axial development. Here we show that absence of Wnt3 in the posterior visceral endoderm leads to delayed formation of the primitive streak and that interplay between anterior and posterior visceral endoderm restricts the position of the primitive streak. Embryos lacking Wnt3 in the visceral endoderm, however, appear normal by E9.5. Our results suggest a model for axial development in which multiple signals are required for anteroposterior axial development in mammals. PMID:25907228

  19. Recording the synchrotron radiation by a picosecond streak camera for bunch diagnostics in cyclic accelerators

    NASA Astrophysics Data System (ADS)

    Vereshchagin, A. K.; Vorob'ev, N. S.; Gornostaev, P. B.; Dorokhov, V. L.; Kryukov, S. S.; Lozovoi, V. I.; Meshkov, O. I.; Nikiforov, D. A.; Smirnov, A. V.; Shashkov, E. V.; Schelev, M. Ya

    2016-02-01

    A PS-1/S1 picosecond streak camera with a linear sweep is used to measure temporal characteristics of synchrotron radiation pulses on a damping ring (DR) at the Budker Institute of Nuclear Physics (BINP) of the Siberian Branch of the Russian Academy of Sciences (Novosibirsk). The data obtained allow a conclusion as to the formation processes of electron bunches and their 'quality' in the DR after injection from the linear accelerator. The expediency of employing the streak camera as a part of an optical diagnostic accelerator complex for adjusting the injection from a linear accelerator is shown. Discussed is the issue of designing a new-generation dissector with a time resolution up to a few picoseconds, which would allow implementation of a continuous bunch monitoring in the DR during mutual work with the electron-positron colliders at the BINP.

  20. Route to One Atomic Unit of Time: Development of a Broadband Attosecond Streak Camera

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Zhang, Qi; Chini, Michael; Chang, Zenghu

    A new attosecond streak camera based on a three-meter-long magnetic-bottle time-of-flight electron spectrometer (MBES) is developed. The temporal resolution of the photoelectron detection system is measured to be better than 250 ps, which is sufficient to achieve an energy resolution of 0.5 eV at 150 eV photoelectron energy. In preliminary experiments, a 94-as isolated XUV pulse was generated and characterized. With a new algorithm to retrieve the amplitude and phase of XUV pulses (PROOF—phase retrieval by omega oscillation filtering), the attosecond streak camera will be able to characterize isolated attosecond pulses as short as one atomic unit of time (25 as).

  1. Single-shot visualization of evolving laser wakefields using an all-optical streak camera.

    PubMed

    Li, Zhengyan; Tsai, Hai-En; Zhang, Xi; Pai, Chih-Hao; Chang, Yen-Yu; Zgadzaj, Rafal; Wang, Xiaoming; Khudik, V; Shvets, G; Downer, M C

    2014-08-22

    We visualize ps-time-scale evolution of an electron density bubble--a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse--from the phase "streak" that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometric techniques, reveal the formation, propagation, and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell simulations validate the observed density-dependent bubble evolution, and correlate it with the generation of a quasimonoenergetic ∼ 100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at a plasma density n(e) ≈ 2 × 10(19) cm(-3), inefficient acceleration at lower density, and dephasing limits at higher density. PMID:25192102

  2. Temporal resolution limit estimation of x-ray streak cameras using a CsI photocathode

    SciTech Connect

    Li, Xiang; Gu, Li; Zong, Fangke; Zhang, Jingjin; Yang, Qinlao

    2015-08-28

    A Monte Carlo model is developed and implemented to calculate the characteristics of x-ray induced secondary electron (SE) emission from a CsI photocathode used in an x-ray streak camera. Time distributions of emitted SEs are investigated with an incident x-ray energy range from 1 to 30 keV and a CsI thickness range from 100 to 1000 nm. Simulation results indicate that SE time distribution curves have little dependence on the incident x-ray energy and CsI thickness. The calculated time dispersion within the CsI photocathode is about 70 fs, which should be the temporal resolution limit of x-ray streak cameras that use CsI as the photocathode material.

  3. A novel compact high speed x-ray streak camera (invited)

    SciTech Connect

    Hares, J. D.; Dymoke-Bradshaw, A. K. L.

    2008-10-15

    Conventional in-line high speed streak cameras have fundamental issues when their performance is extended below a picosecond. The transit time spread caused by both the spread in the photoelectron (PE) ''birth'' energy and space charge effects causes significant electron pulse broadening along the axis of the streak camera and limits the time resolution. Also it is difficult to generate a sufficiently large sweep speed. This paper describes a new instrument in which the extraction electrostatic field at the photocathode increases with time, converting time to PE energy. A uniform magnetic field is used to measure the PE energy, and thus time, and also focuses in one dimension. Design calculations are presented for the factors limiting the time resolution. With our design, subpicosecond resolution with high dynamic range is expected.

  4. Mach-zehnder based optical marker/comb generator for streak camera calibration

    SciTech Connect

    Miller, Edward Kirk

    2015-03-03

    This disclosure is directed to a method and apparatus for generating marker and comb indicia in an optical environment using a Mach-Zehnder (M-Z) modulator. High speed recording devices are configured to record image or other data defining a high speed event. To calibrate and establish time reference, the markers or combs are indicia which serve as timing pulses (markers) or a constant-frequency train of optical pulses (comb) to be imaged on a streak camera for accurate time based calibration and time reference. The system includes a camera, an optic signal generator which provides an optic signal to an M-Z modulator and biasing and modulation signal generators configured to provide input to the M-Z modulator. An optical reference signal is provided to the M-Z modulator. The M-Z modulator modulates the reference signal to a higher frequency optical signal which is output through a fiber coupled link to the streak camera.

  5. High-Speed Observer: Automated Streak Detection for the Aerospike Engine

    NASA Technical Reports Server (NTRS)

    Rieckhoff, T. J.; Covan, M. A.; OFarrell, J. M.

    2001-01-01

    A high-frame-rate digital video camera, installed on test stands at Stennis Space Center (SSC), has been used to capture images of the aerospike engine plume during test. These plume images are processed in real time to detect and differentiate anomalous plume events. Results indicate that the High-Speed Observer (HSO) system can detect anomalous plume streaking events that are indicative of aerospike engine malfunction.

  6. Complete genome sequence of an emerging genotype of tobacco streak virus in the United States.

    PubMed

    Padmanabhan, Chellappan; Gao, Shan; Li, Rugang; Zhang, Shouan; Fei, Zhangjun; Ling, Kai-Shu

    2014-01-01

    We report here the complete genome sequence of an emerging genotype of tobacco streak virus (TSV) infecting zucchini squash in Florida (TSV_FL13-07), obtained using deep sequencing of short RNAs (sRNAs) and validation by Sanger sequencing. TSV_FL13-07 shares only <90% sequence identity in all three genomic RNAs to several known U.S. isolates. PMID:25377714

  7. Molecular organization of the cholesteryl ester droplets in the fatty streaks of human aorta.

    PubMed Central

    Engelman, D M; Hillman, G M

    1976-01-01

    X-ray diffraction patterns from human arterial specimens containing atherosclerotic fatty streak lesions exhibited a single sharp reflection, corresponding to a structural spacing of about 35 A. Specimens without lesions did not. When specimens with fatty streaks were heated, an order-to-disorder phase transition was revealed by the disappearance of the sharp reflection. The transition was thermally reversible and its temperature varied from aorta to aorta over a range from 28 degrees to 42 degrees C. Since cholesteryl ester droplets are a major component of fatty streaks, comparison studies were made of the diffraction behavior from pure cholesteryl esters. We found that the diffraction patterns of the fatty streak material could be accounted for by the organization of the cholesteryl esters into a liquid-crystalline smectic phase that melts from the smectic to a less ordered phase upon heating. When combined with the conclusions of others from polarized light microscopy, our study shows that a droplet in the smectic phase has well-defined concentric layers of lipid molecules. In each layer, the long axes of the molecules have a net radial orientation with respect to the droplet, but the side-to-side organization is disordered. We suggest that the accessibility of portions of the lipids for specific binding to enzymes or transport proteins may be restricted when they are in the smectic state, and that exchange of lipids with surrounding membranes or other potential binding sites may likewise be inhibited. The restriction in the smectic phase should be greater than in the less ordered phases that exist at higher temperatures. Images PMID:965500

  8. Comparative Sequence Analysis of the Sorghum Rph Region and the Maize Rp1 Resistance Gene Complex

    PubMed Central

    Ramakrishna, Wusirika; Emberton, John; SanMiguel, Phillip; Ogden, Matthew; Llaca, Victor; Messing, Joachim; Bennetzen, Jeffrey L.

    2002-01-01

    A 268-kb chromosomal segment containing sorghum (Sorghum bicolor) genes that are orthologous to the maize (Zea mays) Rp1 disease resistance (R) gene complex was sequenced. A region of approximately 27 kb in sorghum was found to contain five Rp1 homologs, but most have structures indicating that they are not functional. In contrast, maize inbred B73 has 15 Rp1 homologs in two nearby clusters of 250 and 300 kb. As at maize Rp1, the cluster of R gene homologs is interrupted by the presence of several genes that appear to have no resistance role, but these genes were different from the ones found within the maize Rp1 complex. More than 200 kb of DNA downstream from the sorghum Rp1-orthologous R gene cluster was sequenced and found to contain many duplicated and/or truncated genes. None of the duplications currently exist as simple tandem events, suggesting that numerous rearrangements were required to generate the current genomic structure. Four truncated genes were observed, including one gene that appears to have both 5′ and 3′ deletions. The maize Rp1 region is also unusually enriched in truncated genes. Hence, the orthologous maize and sorghum regions share numerous structural features, but all involve events that occurred independently in each species. The data suggest that complex R gene clusters are unusually prone to frequent internal and adjacent chromosomal rearrangements of several types. PMID:12481055

  9. A maize wall-associated kinase confers quantitative resistance to head smut.

    PubMed

    Zuo, Weiliang; Chao, Qing; Zhang, Nan; Ye, Jianrong; Tan, Guoqing; Li, Bailin; Xing, Yuexian; Zhang, Boqi; Liu, Haijun; Fengler, Kevin A; Zhao, Jing; Zhao, Xianrong; Chen, Yongsheng; Lai, Jinsheng; Yan, Jianbing; Xu, Mingliang

    2015-02-01

    Head smut is a systemic disease in maize caused by the soil-borne fungus Sporisorium reilianum that poses a grave threat to maize production worldwide. A major head smut quantitative resistance locus, qHSR1, has been detected on maize chromosome bin2.09. Here we report the map-based cloning of qHSR1 and the molecular mechanism of qHSR1-mediated resistance. Sequential fine mapping and transgenic complementation demonstrated that ZmWAK is the gene within qHSR1 conferring quantitative resistance to maize head smut. ZmWAK spans the plasma membrane, potentially serving as a receptor-like kinase to perceive and transduce extracellular signals. ZmWAK was highly expressed in the mesocotyl of seedlings where it arrested biotrophic growth of the endophytic S. reilianum. Impaired expression in the mesocotyl compromised ZmWAK-mediated resistance. Deletion of the ZmWAK locus appears to have occurred after domestication and spread among maize germplasm, and the ZmWAK kinase domain underwent functional constraints during maize evolution. PMID:25531751

  10. Maize ZmRACK1 Is Involved in the Plant Response to Fungal Phytopathogens

    PubMed Central

    Wang, Baosheng; Yu, Jingjuan; Zhu, Dengyun; Chang, Yujie; Zhao, Qian

    2014-01-01

    The receptor for activated C kinase 1 (RACK1) belongs to a protein subfamily containing a tryptophan-aspartic acid-domain (WD) repeat structure. Compelling evidence indicates that RACK1 can interact with many signal molecules and affect different signal transduction pathways. In this study, we cloned a maize RACK1 gene (ZmRACK1) by RT-PCR. The amino acid sequence of ZmRACK1 had seven WD repeats in which there were typical GH (glycine-histidine) and WD dipeptides. Comparison with OsRACK1 from rice revealed 89% identity at the amino acid level. Expression pattern analysis by RT-PCR showed that ZmRACK1 was expressed in all analyzed tissues of maize and that its transcription in leaves was induced by abscisic acid and jasmonate at a high concentration. Overexpression of ZmRACK1 in maize led to a reduction in symptoms caused by Exserohilum turcicum (Pass.) on maize leaves. The expression levels of the pathogenesis-related protein genes, PR-1 and PR-5, increased 2.5–3 times in transgenic maize, and reactive oxygen species production was more active than in the wild-type. Yeast two-hybrid assays showed that ZmRACK1 could interact with RAC1, RAR1 and SGT1. This study and previous work leads us to believe that ZmRACK1 may form a complex with regulators of plant disease resistance to coordinate maize reactions to pathogens. PMID:24865494

  11. 2-ps Hard X-Ray Streak Camera Measurements at Sector 7 Beamline of the Advanced Photon Source

    SciTech Connect

    Chollet, M.; Ahr, B.; Walko, D.A.; Rose-Petruck, C.; Adams, B.

    2011-08-02

    A hard X-ray streak camera capable of 2-ps time resolution is in operation at the Sector 7 beamline of the Advanced Photon Source. It is used for laser-pump, X-ray probe experiments using the Ti:Sapphire femtosecond laser system installed on the beamline. This streak camera, combined with standardized and prealigned experimental setups, can perform time-resolved liquid-phase absorption spectroscopy, reflectivity, and diffraction experiments.

  12. Reducing photoperiod response of tropical maize germplasm for use in Midwestern maize introgression

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Germplasm Enhancement of Maize Project (GEM) is a cooperative effort of USDA-ARS, public and private sector scientists to broaden the genetic diversity of maize germplasm. Tropical maize germplasm is an important source of alleles for biotic and abiotic stress resistance and numerous value-adde...

  13. MaizeGDB: Global support for maize research through open access information [abstract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the open-access global repository for maize genetic and genomic information – from single genes that determine nutritional quality to whole genome-scale data for complex traits including yield and drought tolerance. The data and tools at MaizeGDB enable researchers from Ethiopia to Ghan...

  14. Kernel Composition, Starch Structure, and Enzyme Digestibility of Opaque-2 Maize and Quality Protein Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Objectives of this study were to understand how opaque-2 (o2) mutation and quality protein maize (QPM) affect maize kernel composition and starch structure, property, and enzyme digestibility. Kernels of o2 maize contained less protein (9.6−12.5%) than those of the wild-type (WT) counterparts (12...

  15. Development of intelligent control system for X-ray streak camera in diagnostic instrument manipulator

    NASA Astrophysics Data System (ADS)

    Pei, Chengquan; Wu, Shengli; Tian, Jinshou; Liu, Zhen; Fang, Yuman; Gao, Guilong; Liang, Lingliang; Wen, Wenlong

    2015-11-01

    An intelligent control system for an X ray streak camera in a diagnostic instrument manipulator (DIM) is proposed and implemented, which can control time delay, electric focusing, image gain adjustment, switch of sweep voltage, acquiring environment parameters etc. The system consists of 16 A/D converters and 16 D/A converters, a 32-channel general purpose input/output (GPIO) and two sensors. An isolated DC/DC converter with multi-outputs and a single mode fiber were adopted to reduce the interference generated by the common ground among the A/D, D/A and I/O. The software was designed using graphical programming language and can remotely access the corresponding instrument from a website. The entire intelligent control system can acquire the desirable data at a speed of 30 Mb/s and store it for later analysis. The intelligent system was implemented on a streak camera in a DIM and it shows a temporal resolution of 11.25 ps, spatial distortion of less than 10% and dynamic range of 279:1. The intelligent control system has been successfully used in a streak camera to verify the synchronization of multi-channel laser on the Inertial Confinement Fusion Facility.

  16. High-Throughput Single-Cell Cultivation on Microfluidic Streak Plates.

    PubMed

    Jiang, Cheng-Ying; Dong, Libing; Zhao, Jian-Kang; Hu, Xiaofang; Shen, Chaohua; Qiao, Yuxin; Zhang, Xinyue; Wang, Yapei; Ismagilov, Rustem F; Liu, Shuang-Jiang; Du, Wenbin

    2016-04-01

    This paper describes the microfluidic streak plate (MSP), a facile method for high-throughput microbial cell separation and cultivation in nanoliter sessile droplets. The MSP method builds upon the conventional streak plate technique by using microfluidic devices to generate nanoliter droplets that can be streaked manually or robotically onto petri dishes prefilled with carrier oil for cultivation of single cells. In addition, chemical gradients could be encoded in the droplet array for comprehensive dose-response analysis. The MSP method was validated by using single-cell isolation of Escherichia coli and antimicrobial susceptibility testing of Pseudomonas aeruginosa PAO1. The robustness of the MSP work flow was demonstrated by cultivating a soil community that degrades polycyclic aromatic hydrocarbons. Cultivation in droplets enabled detection of the richest species diversity with better coverage of rare species. Moreover, isolation and cultivation of bacterial strains by MSP led to the discovery of several species with high degradation efficiency, including four Mycobacterium isolates and a previously unknown fluoranthene-degrading Blastococcus species. PMID:26850294

  17. Attosecond streaking of molecules in the low-energy region studied by a wavefunction splitting scheme

    NASA Astrophysics Data System (ADS)

    Hou, Xue-Feng; Peng, Liang-You; Ning, Qi-Cheng; Gong, Qihuang

    2012-04-01

    We present a theoretical study of the low-energy photoelectron spectra of hydrogen molecular ion generated by a single attosecond pulse in the presence of an infrared (IR) laser field. In order to investigate this type of attosecond streaking of molecules, we developed a very efficient grid-based numerical method to solve the two-centre time-dependent Schrödinger equation (TDSE) in the prolate spheroidal coordinates. Specifically, the radial coordinate is discretized with the finite-element discrete variable representation (FE-DVR) for easy parallel computation and the angular coordinate with the usual DVR. A wavefunction splitting scheme is utilized to reduce the demanding requirement of the computational resource to solve the corresponding TDSE when an IR field is present. After verification of the accuracy and efficiency of our method, we then apply it to investigate the attosecond streaking spectra of H+2 in the low-energy region. In contrast to the usual attosecond streaking in the high-energy region, part of the low-energy electrons may be driven back to rescatter with the residual two-centre core. Very interesting interference structures are present in the low-energy region. When the internuclear distance is small, they are very similar to what we have recently observed in the atomic case.

  18. Optical fiducial timing system for X-ray streak cameras with aluminum coated optical fiber ends

    DOEpatents

    Nilson, David G.; Campbell, E. Michael; MacGowan, Brian J.; Medecki, Hector

    1988-01-01

    An optical fiducial timing system is provided for use with interdependent groups of X-ray streak cameras (18). The aluminum coated (80) ends of optical fibers (78) are positioned with the photocathodes (20, 60, 70) of the X-ray streak cameras (18). The other ends of the optical fibers (78) are placed together in a bundled array (90). A fiducial optical signal (96), that is comprised of 2.omega. or 1.omega. laser light, after introduction to the bundled array (90), travels to the aluminum coated (82) optical fiber ends and ejects quantities of electrons (84) that are recorded on the data recording media (52) of the X-ray streak cameras (18). Since both 2.omega. and 1.omega. laser light can travel long distances in optical fiber with only a slight attenuation, the initial arial power density of the fiducial optical signal (96) is well below the damage threshold of the fused silica or other material that comprises the optical fibers (78, 90). Thus the fiducial timing system can be repeatably used over long durations of time.

  19. Altitude Starting Characteristics of an Afterburner with Autoignition and Hot-streak Ignition

    NASA Technical Reports Server (NTRS)

    Renas, P E; Jansen, E T; Harvey, R W , Sr

    1953-01-01

    An investigation was conducted in an altitude test chamber at the NACA Lewis Laboratory to determine the altitude starting characteristics of an afterburner with autoignition and with hot-streak ignition. Transient afterburner ignition data were obtained over a range of altitudes from 30,000 to 50,000 feet at a flight Mach number of 0.60. Afterburner ignition with a torch igniter located axially at approximately the midpoint of the combustion chamber was possible over the entire range, but ignition ignition with a torch igniter located in the transition section 1 5/8 inches upstream of the turbine stators proved unsatisfactory at an altitude of 50,000 feet due to the inability to obtain flame through the turbine. Increasing the afterburner-inlet total pressure at a constant afterburner fuel-air ratio decreased the afterburner ignition time. Hot-streak ignition was possible within 2 seconds after the time required to obtain the preset, normal afterburner fuel pressure, whereas autoignition required 4 to 7 seconds for the range of altitudes investigated. Following the ignition there was a period of oscillatory operation existing in the engine-afterburner before steady-state operation was attained. The time required for steady-state stable operation decreased as afterburner inlet total pressure increased. The duration of oscillations also decreased with hot-streak ignition because the fuel-air mixture was ignited before a large volume of combustible mixture was accumulated in the afterburner.

  20. Unsteady numerical simulation of hot streak/blades interaction and film cooling

    NASA Astrophysics Data System (ADS)

    Yi, Weilin; Ji, Lucheng; Xiao, Yunhan

    2010-10-01

    Deeply research on management and application of hot streak is an important way to breakthrough technique obstacle of aero engine hot components. Numerical method is a useful instrument to investigate the correlative problems. Firstly the paper developed independently three dimensional unsteady parallel computational code-MpiTurbo based on Fortran 90 and MPI at Linux operating system. Then unsteady numerical simulation was carried out to investigate impacts of the factors, which included circumferential locations of hot streak and clocking positions of blade rows, on the thermal environment of a 1+1 counter-rotating turbine. The results clearly indicated that clocking positions of hot streak/blade row and blade row/blade row had great influence on the time-averaged temperature distribution of the third blade row. Therefore, it can be effective for improving thermal environment of turbine to optimize blade parameters and clocking positions. Lastly film cooling layout was designed by the repetitious steady simulation based on source term method. And the flow structure detail was given by the unsteady simulation.

  1. Laser Activated Streak Camera for Measurement of Electron Pulses with Femtosecond Resolution

    NASA Astrophysics Data System (ADS)

    Zandi, Omid; Desimone, Alice; Wilkin, Kyle; Yang, Jie; Centurion, Martin

    2015-05-01

    The duration of femtosecond electron pulses used in time-resolved diffraction and microscopy experiments is challenging to measure in-situ. To overcome this problem, we have fabricated a streak camera that uses the time-varying electric field of a discharging parallel plate capacitor. The capacitor is discharged using a laser-activated GaAs photoswitch, resulting in a damped oscillation of the electric field. The delay time between the laser pulse and electron pulse is set so that the front and back halves of the bunch encounter opposite electric fields of the capacitor and are deflected in opposite directions. Thus, the electron bunch appears streaked on the detector with a length proportional to its duration. The temporal resolution of the streak camera is proportional to the maximum value of the electric field and the frequency of the discharge oscillation. The capacitor is charged by high voltage short pulses to achieve a high electric field and prevent breakdown. We have achieved an oscillation frequency in the GHz range by reducing the circuit size and hence its inductance. The camera was used to measure 100 keV electron pulses with up to a million electrons that are compressed transversely by magnetic lenses and longitudinally by an RF cavity. This work was supported mainly by the Air Force Office of Scientific Research, Ultrashort Pulse Laser Matter Interaction program, under grant # FA9550-12-1-0149.

  2. Low Albedo Surfaces and Eolian Sediment: Mars Orbiter Camera Views of Western Arabia Terra Craters and Wind Streaks

    NASA Technical Reports Server (NTRS)

    Edgett, Kenneth S.

    2001-01-01

    High spatial resolution (1.5 to 12 m/pixel) Mars Global Surveyor Mars Orbiter Camera images obtained September 1997 through June 2001 indicate that the large, dark wind streaks of western Arabia Terra each originate at a barchan dune field on a crater floor. The streaks consist of a relatively thin coating of sediment deflated from the dune fields and their vicinity. This sediment drapes a previous mantle that more thickly covers nearly all of western Arabia Terra. No dunes or eolian bedforms are found within the dark wind streaks, nor do any of the intracrater dunes climb up crater walls to provide sand to the wind streaks. The relations between dunes, wind streak, and subjacent terrain imply that dark-toned grains finer than those which comprise the dunes are lifted into suspension and carried out of the craters to be deposited on the adjacent terrain. Such grains are most likely in the silt size range (3.9-62.5 micrometers). The streaks change in terms of extent, relative albedo, and surface pattern over periods measured in years, but very little evidence for recent eolian activity (dust plumes, storms, dune movement) has been observed.

  3. In planta reduction of maize seedling stalk lesions by the bacterial endophyte Bacillus mojavensis.

    PubMed

    Bacon, Charles W; Hinton, Dorothy M

    2011-06-01

    Maize (Zea mays L.) is susceptible to infection by Fusarium verticillioides through autoinfection and alloinfection, resulting in diseases and contamination of maize kernels with the fumonisin mycotoxins. Attempts at controlling this fungus are currently being done with biocontrol agents such as bacteria, and this includes bacterial endophytes, such as Bacillus mojavensis . In addition to producing fumonisins, which are phytotoxic and mycotoxic, F. verticillioides also produces fusaric acid, which acts both as a phytotoxin and as an antibiotic. The question now is Can B. mojavensis reduce lesion development in maize during the alloinfection process, simulated by internode injection of the fungus? Mutant strains of B. mojavensis that tolerate fusaric acid were used in a growth room study to determine the development of stalk lesions, indicative of maize seedling blight, by co-inoculations with a wild-type strain of F. verticillioides and with non-fusaric acid producing mutants of F. verticillioides. Lesions were measured on 14-day-old maize stalks consisting of treatment groups inoculated with and without mutants and wild-type strains of bacteria and fungi. The results indicate that the fusaric-acid-tolerant B. mojavensis mutant reduced stalk lesions, suggesting an in planta role for this substance as an antibiotic. Further, lesion development occurred in maize infected with F. verticillioides mutants that do not produce fusaric acid, indicating a role for other phytotoxins, such as the fumonisins. Thus, additional pathological components should be examined before strains of B. mojavensis can be identified as being effective as a biocontrol agent, particularly for the control of seedling disease of maize. PMID:21635192

  4. The iojap gene in maize

    SciTech Connect

    Martienssen, Robert

    2001-12-01

    The classical maize mutant iojap (Iodent japonica) has variegated green and white leaves. Green sectors have cells with normal chloroplasts whereas white sectors have cells where plastids fail to differentiate. These mutant plastids, when transmitted through the female gametophyte, do not recover in the presence of wild type Iojap. We cloned the Ij locus, and we have investigated the mechanism of epigenetic inheritance and phenotypic expression. More recently, a modifier of this type of variegation, ''Inhibitor of striate'', has also been cloned. Both the iojap and inhibitor of striate proteins have homologs in bacteria and are members of ancient conserved families found in multiple species. These tools can be used to address fundamental questions of inheritance and variegation associated with this classical conundrum of maize genetics. Since the work of Rhoades there has been considerable speculation concerning the nature of the Iojap gene product, the origin of leaf variegation and the mechanism behind the material inheritance of defective plastids. This has made Iojap a textbook paradigm for cytoplasmic inheritance and nuclear-organellar interaction for almost 50 years. Cloning of the Iojap gene in maize, and homologs in other plants and bacteria, provides a new means to address the origin of heteroplastidity, variegation and cytoplasmic inheritance in higher plants.

  5. Comparative Genome Mapping of Sorghum and Maize

    PubMed Central

    Whitkus, R.; Doebley, J.; Lee, M.

    1992-01-01

    Linkage relationships were determined among 85 maize low copy number nuclear DNA probes and seven isozyme loci in an F(2) population derived from a cross of Sorghum bicolor ssp. bicolor X S. bicolor ssp. arundinaceum. Thirteen linkage groups were defined, three more than the 10 chromosomes of sorghum. Use of maize DNA probes to produce the sorghum linkage map allowed us to make several inferences concerning processes involved in the evolutionary divergence of the maize and sorghum genomes. The results show that many linkage groups are conserved between these two genomes and that the amount of recombination in these conserved linkage groups is roughly equivalent in maize and sorghum. Estimates of the proportions of duplicated loci suggest that a larger proportion of the loci are duplicated in the maize genome than in the sorghum genome. This result concurs with a prior estimate that the nuclear DNA content of maize is three to four times greater than that of sorghum. The pattern of conserved linkages between maize and sorghum is such that most sorghum linkage groups are composed of loci that map to two maize chromosomes. This pattern is consistent with the hypothesized ancient polyploid origin of maize and sorghum. There are nine cases in which locus order within shared linkage groups is inverted in sorghum relative to maize. These may have arisen from either inversions or intrachromosomal translocations. We found no evidence for large interchromosomal translocations. Overall, the data suggest that the primary processes involved in divergence of the maize and sorghum genomes were duplications (either by polyploidy or segmental duplication) and inversions or intrachromosomal translocations. PMID:1360933

  6. Quantification of southern rice black streaked dwarf virus and rice black streaked dwarf virus in the organs of their vector and nonvector insect over time.

    PubMed

    Hajano, Jamal-U-Ddin; Wang, Biao; Ren, Yingdang; Lu, Chuantao; Wang, Xifeng

    2015-10-01

    Southern rice black streaked dwarf virus (SRBSDV) and rice black streaked dwarf virus (RBSDV) are serious rice-infecting reoviruses, which are transmitted by different planthoppers in a persistent propagative manner. In this study, we quantitatively compared the spatial distribution of SRBSDV and RBSDV contents over time in their vector and nonvector insects using real time-PCR. Genome equivalent copies (GEC) were assessed every 2 days from 0 to 14 days after a 3-days acquisition access period (AAP) on infected plants. Results revealed 293.2±21.6 to 404.1±46.4 SRBSDV GEC/ng total RNA in whole body of white-backed planthopper (WBPH, Sogatella furcifera) at day 0 and 12 and 513.5±88.4 to 816.8±110.7 RBSDV GEC/ng total RNA in the whole body of small brown planthopper (SBPH, Laodelphax striatellus) at day 0 and 14, respectively, after 3-days AAP. Highest GEC of both viruses were found in the gut of their respective vectors. Although SRBSDV was detected in the gut of SBPH, it did not spread into the hemolymph or other organs. After an 8-day latent period, the transmission efficiency of SRBSDV and RBSDV by their respective vectors was significantly positively correlated with GEC in the salivary gland (r(2)=0.7808, P=0.0036 and r(2)=0.9351, P<0.0001, respectively, at α=0.05). Together, these results confirm that accumulation of >200 SRBSDV or RBSDV GEC/ng total RNA in the gut of vector, indicated threshold for further spread and the virus content in the salivary gland was significantly correlated with transmission efficiency by their respective vectors. PMID:26116274

  7. Measuring 8–250 ps short pulses using a high-speed streak camera on kilojoule, petawatt-class laser systems

    SciTech Connect

    Qiao, J.; Jaanimagi, P. A.; Boni, R.; Bromage, J.; Hill, E.

    2013-07-15

    Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a more-uniform streak image and enables one to characterize space-charge-induced pulse-broadening effects.

  8. Synchronous time-resolved optical and x-ray emission from simultaneous optical and x-ray streak cameras driven by a master ramp generator

    SciTech Connect

    Balmer, J.E.; Lampert, W.; Roschger, E.; Hares, J.D.; Kilkenny, J.D.

    1985-05-01

    An optical and an x-ray streak camera have been synchronized by driving the deflection plates of both cameras from the same ramp generator. The relative timing of the two cameras was calibrated by running UV light onto the x-ray streak camera. The x-ray streak camera was then used to measure the time of the x-ray emission from a laser plasma with respect to the laser pulse.

  9. A meteorologically driven maize stress indicator model

    NASA Technical Reports Server (NTRS)

    Taylor, T. W.; Ravet, F. W. (Principal Investigator)

    1981-01-01

    A maize soil moisture and temperature stress model is described which was developed to serve as a meteorological data filter to alert commodity analysts to potential stress conditions in the major maize-producing areas of the world. The model also identifies optimum climatic conditions and planting/harvest problems associated with poor tractability.

  10. Use of tropical maize for bioethanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lo...

  11. Maize metabolic network construction and transcriptome analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A framework for understanding the synthesis and catalysis of metabolites and other biochemicals by proteins is crucial for unraveling the physiology of cells. To create such a framework for Zea mays ssp. mays (maize), we developed MaizeCyc a metabolic network of enzyme catalysts, proteins, carbohydr...

  12. The genetic architecture of maize height

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Height is one of the most heritable and easily measured traits in maize (Zea mays L.). Given a pedigree or estimates of the genomic identity-by-state (IBS) among related plants, height is also accurately predictable. But, mapping alleles explaining natural variation in maize height remains a formida...

  13. Aflatoxin accumulation in a maize diallel cross

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aflatoxins, produced by the fungus Aspergillus flavus, occur naturally in maize. Contamination of maize grain with aflatoxin is a major food and feed safety problem and greatly reduces the value of the grain. Plant resistance is generally considered a highly desirable approach to reduction or elimin...

  14. Germplasm Enhancement of Maize (GEM) Project Overview

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Germplasm Enhancement of Maize Project (GEM) is a collaborative effort of public and private sector researchers to broaden and enhance the maize germplasm base. The GEM Project has cooperators from 26 private companies, 17 Universities, 7 USDA-ARS Research Units, 1 NGO, and 12 international pub...

  15. MaizeGDB's New Data Types, Resources, and Activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the Maize Genetics and Genomics Database. Available at MaizeGDB are diverse data that support maize research including maps, gene product information, loci and their various alleles, phenotypes (both naturally occurring and as a result of directed mutagenesis), stocks, sequences, molecul...

  16. Functional Allelic Variation at Key Photoperiod Response QTL in Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tropical maize represents a valuable genetic resource containing unique alleles not present in elite temperate maize. The strong delay in flowering in response to long daylength photoperiods exhibited by most tropical maize hinders its incorporation into temperate maize breeding programs. We tested ...

  17. MaizeGDB's new data types, resources, and activities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    MaizeGDB is the Maize Genetics and Genomics Database. Available at MaizeGDB are diverse data that support maize research including maps, gene product information, loci and their various alleles, phenotypes (both naturally occurring and as a result of directed mutagenesis), stocks, sequences, molecul...

  18. Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems

    SciTech Connect

    Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

    2012-08-15

    This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 {mu}m) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ('hotspot') was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm{sup 2}/steradian/nm). Error analysis shows this method to be accurate to within +/- 20%, which represents a high level of accuracy for this type of measurement.

  19. Significant seismic streaks corresponding to lithological contrasts in Mesozoic and Paleozoic accretion units, southwest Japan

    NASA Astrophysics Data System (ADS)

    Maeda, S.; Toda, S.; Katao, H.

    2014-12-01

    While high-density seismic streaks are commonly seen in aftershocks of a strike-slip earthquake, significant linear clusters in background seismicity are rare. A typical example of such sustained streaks is observed along the creeping section of the San Andreas fault, in which strain localization associated with frictional heterogeneity takes a responsibility. Here we show other examples from Tamba and Wakayama regions, around Osaka-Kyoto district, where a number of several-to-20-km-long seismic streaks are observed. We explore the role of geologic heterogeneity into the seismicity comparing spatial distribution of earthquakes with geologic structure in both regions, where a significant high background rate of seismicity has been continuously recorded since the mid-1900. Epicenters of numerous small earthquakes are located mainly on the Mesozoic metamorphic rocks and Mesozoic-Paleozoic accretion units, whereas low seismicity is characterized in granite and ultra-mafic rocks. Within the Wakayama seismic zone, in particular, we observe many E-W and ENE-WSW trending dense seismic clusters in hypocenters of Japan Meteorological Agency (JMA) data relocated with the hypo DD algorithm of Waldhauser and Ellsworth (2000). Most of the E-W trending seismic clusters possibly correspond to the E-W trending local scale geologic faults, folds, bedding planes, and schistosity. However, well-determined fault plane solutions by JMA and the National Research Institute for Earth Science and Disaster Prevention (NIED) show NS-trending reverse faults corresponding to EW compression. We further sought the focal mechanisms for smaller earthquakes using waveform data recorded in the SATARN seismic network system of DPRI, Kyoto University. As a result, among the many reverse fault mechanisms, we found some amounts of strike-slip ones, which may associate with the visible EW-trending seismic clusters.

  20. Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems

    NASA Astrophysics Data System (ADS)

    Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

    2012-08-01

    This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 μm) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ("hotspot") was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm2/steradian/nm). Error analysis shows this method to be accurate to within +/- 20%, which represents a high level of accuracy for this type of measurement.

  1. A Dust Devil Making a Streak and Climbing a Crater Wall

    NASA Technical Reports Server (NTRS)

    2002-01-01

    MGS MOC Release No. MOC2-318, 8 August 2002 [figure removed for brevity, see original site] One of the key elements of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is to look for and monitor changes taking place on the planet over the course of a second--and, eventually, a third--martian year. MGS is now well into its second Mars year, which will draw to a close in December 2002. Among the changes the MOC has observed are streaks believed to be caused by the passage of dust devils. Thousands of MOC images show these streaks, dozens show that they change over time, but far fewer images have actually captured a dust devil in the act of creating a streak. At the center right of this image (above left) is a dust devil that, on May 21, 2002, was seen climbing the wall of a crater at 4.1oS, 9.5oW. This crater (above right) is in western Terra Meridiani. The dust devil was moving toward the northeast (upper right), leaving behind a dark trail where a thin coating of surficial dust was removed or disrupted as the dust devil advanced. Dust devils most commonly form after noon on days when the martian air is still (that is, when there isn't even a faint breeze). On such days, the ground is better able to heat up the air immediately above the surface. As the warmed near-surface air begins to rise, it also begins to spin, creating a vortex. The spinning column then moves across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it a tornado-like appearance. The dust devil in this image has a very short, dark shadow cast to the right of the bright column; this shadow is short because the sun was nearly overhead.

  2. Direct Shock-Timing Measurements in CH Using Streaked X-Ray Radiography

    NASA Astrophysics Data System (ADS)

    Nilson, P. M.; Lafon, M.; Stillman, C. R.; Mileham, C.; Boni, R.; Boehly, T. R.; Froula, D. H.; Meyerhofer, D. D.

    2014-10-01

    One-dimensional streaked x-ray radiography is used to measure shock coalescence in multishocked plastic. A two-shock system was generated using a ramped drive on the OMEGA EP Laser System. The data show the first shock wave propagating into solid material, followed 2 ns later by the second shock wave. The measured shock trajectories were used to track the system dynamics and determine the shock-coalescence times for different initial shock strengths. The measured shock timings are compared to radiation-hydrodynamic model predictions. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  3. Physics and roller coasters-The Blue Streak at Cedar Point

    NASA Astrophysics Data System (ADS)

    Speers, Robert R.

    1991-06-01

    The use of a roller coaster for external classroom studies of kinematics, forces, dynamics, and energy conservation is discussed. Experimental accelerometer measurements of the vertical forces acting on riders of the Blue Streak at Cedar Point in Sandusky, Ohio are presented. Theoretically, the track profile is used to calculate/predict the vertical forces acting on a rider at the hilltops, valley bottoms, and several other points of interest along the track. Finally the experimental results and theoretical predictions are compared in the context of a rider's experiences.

  4. Capsule Ablator Inflight Performance Measurements Via Streaked Radiography Of ICF Implosions On The NIF*

    NASA Astrophysics Data System (ADS)

    Dewald, E. L.; Tommasini, R.; Mackinnon, A.; MacPhee, A.; Meezan, N.; Olson, R.; Hicks, D.; LePape, S.; Izumi, N.; Fournier, K.; Barrios, M. A.; Ross, S.; Pak, A.; Döppner, T.; Kalantar, D.; Opachich, K.; Rygg, R.; Bradley, D.; Bell, P.; Hamza, A.; Dzenitis, B.; Landen, O. L.; MacGowan, B.; LaFortune, K.; Widmayer, C.; Van Wonterghem, B.; Kilkenny, J.; Edwards, M. J.; Atherton, J.; Moses, E. I.

    2016-03-01

    Streaked 1-dimensional (slit imaging) radiography of 1.1 mm radius capsules in ignition hohlraums was recently introduced on the National Ignition Facility (NIF) and gives an inflight continuous record of capsule ablator implosion velocities, shell thickness and remaining mass in the last 3-5 ns before peak implosion time. The high quality data delivers good accuracy in implosion metrics that meets our requirements for ignition and agrees with recently introduced 2-dimensional pinhole radiography. Calculations match measured trajectory across various capsule designs and laser drives when the peak laser power is reduced by 20%. Furthermore, calculations matching measured trajectories give also good agreement in ablator shell thickness and remaining mass.

  5. Loop-mediated Isothermal Amplification Assay to Rapidly Detect Wheat Streak Mosaic Virus in Quarantined Plants

    PubMed Central

    Lee, Siwon; Kim, Jin-Ho; Choi, Ji-Young; Jang, Won-Cheoul

    2015-01-01

    We developed a loop-mediated isothermal amplification (LAMP) method to rapidly diagnose Wheat streak mosaic virus (WSMV) during quarantine inspections of imported wheat, corn, oats, and millet. The LAMP method was developed as a plant quarantine inspection method for the first time, and its simplicity, quickness, specificity and sensitivity were verified compared to current reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR quarantine methods. We were able to quickly screen for WSMV at quarantine sites with many test samples; thus, this method is expected to contribute to plant quarantine inspections. PMID:26674930

  6. Loop-mediated Isothermal Amplification Assay to Rapidly Detect Wheat Streak Mosaic Virus in Quarantined Plants.

    PubMed

    Lee, Siwon; Kim, Jin-Ho; Choi, Ji-Young; Jang, Won-Cheoul

    2015-12-01

    We developed a loop-mediated isothermal amplification (LAMP) method to rapidly diagnose Wheat streak mosaic virus (WSMV) during quarantine inspections of imported wheat, corn, oats, and millet. The LAMP method was developed as a plant quarantine inspection method for the first time, and its simplicity, quickness, specificity and sensitivity were verified compared to current reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR quarantine methods. We were able to quickly screen for WSMV at quarantine sites with many test samples; thus, this method is expected to contribute to plant quarantine inspections. PMID:26674930

  7. Temporal Characterization of Electron Beam Bunches with a Fast Streak Camera at the JLab FEL Facility

    SciTech Connect

    S. Zhang; S.V. Benson; D. Douglas; D. Hardy; C. Hernandez-Garcia; K. Jordan; G. Neil; Michelle D. Shinn

    2005-08-21

    The design and construction of an optical transport that brings synchrotron radiation from electron bunches to a fast streak camera in a remote area has become a useful tool for online observation of bunch length and stability. This paper will report on the temporal measurements we have done, comparison with simulations, and the on-going work for another imaging optical transport system that will make possible the direct measurement of the longitudinal phase space by measuring the bunch length as a function of energy

  8. Transient electric fields in laser plasmas observed by proton streak deflectometry

    SciTech Connect

    Sokollik, T.; Schnuerer, M.; Ter-Avetisyan, S.; Nickles, P. V.; Risse, E.; Kalashnikov, M.; Sandner, W.; Priebe, G.; Amin, M.; Toncian, T.; Willi, O.; Andreev, A. A.

    2008-03-03

    A novel proton imaging technique was applied which allows a continuous temporal record of electric fields within a time window of several nanoseconds. This 'proton streak deflectometry' was used to investigate transient electric fields of intense ({approx}10{sup 17} W/cm{sup 2}) laser irradiated foils. We found out that these fields with an absolute peak of up to 10{sup 8} V/m extend over millimeter lateral extension and decay at nanosecond duration. Hence, they last much longer than the (approximately picosecond) laser excitation and extend much beyond the laser irradiation focus.

  9. Host specificity in Sporisorium reilianum is determined by distinct mechanisms in maize and sorghum.

    PubMed

    Poloni, Alana; Schirawski, Jan

    2016-06-01

    Smut fungi are biotrophic plant pathogens that exhibit a very narrow host range. The smut fungus Sporisorium reilianum exists in two host-adapted formae speciales: S. reilianum f. sp. reilianum (SRS), which causes head smut of sorghum, and S. reilianum f. sp. zeae (SRZ), which induces disease on maize. It is unknown why the two formae speciales cannot form spores on their respective non-favoured hosts. By fungal DNA quantification and fluorescence microscopy of stained plant samples, we followed the colonization behaviour of both SRS and SRZ on sorghum and maize. Both formae speciales were able to penetrate and multiply in the leaves of both hosts. In sorghum, the hyphae of SRS reached the apical meristems, whereas the hyphae of SRZ did not. SRZ strongly induced several defence responses in sorghum, such as the generation of H2 O2 , callose and phytoalexins, whereas the hyphae of SRS did not. In maize, both SRS and SRZ were able to spread through the plant to the apical meristem. Transcriptome analysis of colonized maize leaves revealed more genes induced by SRZ than by SRS, with many of them being involved in defence responses. Amongst the maize genes specifically induced by SRS were 11 pentatricopeptide repeat proteins. Together with the microscopic analysis, these data indicate that SRZ succumbs to plant defence after sorghum penetration, whereas SRS proliferates in a relatively undisturbed manner, but non-efficiently, on maize. This shows that host specificity is determined by distinct mechanisms in sorghum and maize. PMID:26419898

  10. Fusarium verticillioides gene clusters associated with biotransformation of maize allelopathic compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize produces the benzoxazinones DIMBOA and DIBOA, which naturally transform into the more stable benzoxazolinones MBOA and BOA, respectively. These weed-suppressive allelopathic compounds are also implicated in resistance to microbial diseases and insect feeding. Fusarium verticillioides is able t...

  11. Interaction of fusaric acid and maize seedling lesion development and reduction by isolates of Bacillus mogavensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to autoinfection and alloinfection, maize is parasitized by Fusarium verticillioides and subject to contamination from its mycotoxins, the fumonisins. Attempts at controlling both the disease and mycotoxins resulting from infection are desirable since in some cultivars infections do not always ...

  12. Maize resistance and susceptibility to multiple ear-damaging pests: Progress and prospects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three sets of corn germplasm (including both inbred lines and experimental hybrids from diverse genetic background) have been examined separately for major ear-feeding insect and ear-colonizing disease resistance for two years. The ear-feeding insect damage assessment included corn earworm, maize w...

  13. Using Maize chlorotic dwarf virus to explore future frontiers in plant virology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize chlorotic dwarf virus (MCDV) causes a chlorosis and stunting disease of corn throughout the Midwest United States. It is a waikavirus transmitted by the leafhopper Graminella nigrifrons. Although waikaviruses are economically important viruses in corn and rice, little is known about the viru...

  14. Characterization of strains of Bacillus mojavensis for biocontrol of a maize pathogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The endophytic bacterium, Bacillus mojavensis controls fungal diseases in maize and other plants. The bacterium and its cultural extracts have been shown to be antagonistic to a pathogenic and mycotoxic fungus, Fusarium verticillioides. Extracts prepared from cultures of B. mojavensis contained an...

  15. Maize dwarf mosaic can reduce weed suppressive ability of sweet corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize dwarf mosaic (MDM) stunts corn growth, delays development, and is the most prevalent viral disease of sweet corn grown in many regions of North America and Europe. Although weeds evade control in most sweet corn fields, the extent to which MDM influences the weed suppressive ability of the cro...

  16. Maize dwarf mosaic in sweet corn contributes to weed growth and seed production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize dwarf mosaic (MDM) stunts corn growth, delays development, and is the most prevalent viral disease of sweet corn. Although weeds evade control in most sweet corn fields, the extent to which MDM influences the crop’s weed suppressive ability is unknown. Field studies were conducted over a three...

  17. A genome-wide association study for partial resistance to maize common rust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantitative resistance to maize common rust (causal agent Puccinia sorghi) was assessed in an association mapping population of 274 diverse inbred lines. Resistance to common rust was found to be moderately correlated with resistance to three other diseases and with the severity of the hypersensiti...

  18. Deciphering maize genetics and ecology to reduce insect damage and aflatoxin accumulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ear-colonizing insects and diseases, which reduce yield and impose health threats via mycotoxin contaminations, are critical impediments for maize production in the southern US states. To address this problem a combination of basic and applied research approaches are being conducted by the interdis...

  19. INTEGRATED WEED CONTROL IN MAIZE.

    PubMed

    Latré, J; Dewitte, K; Derycke, V; De Roo, B; Haesaert, G

    2015-01-01

    Integrated pest management has been implemented as a general practice by EU legislation. As weed control actually is the most important crop protection measure in maize for Western Europe, the new legislation will have its impact. The question is of course which systems can be successfully implemented in practice with respect to labour efficiency and economical parameters. During 3 successive growing seasons (2007, 2008, 2009) weed control in maize was evaluated, the main focus was put on different techniques of integrated weed control and was compared with chemical weed control. Additionally, during 4 successive growing seasons (2011, 2012, 2013 and 2014) two objects based on integrated weed control and two objects based on mechanical weed control were compared to about twenty different objects of conventional chemical weed control. One of the objects based on mechanical weed control consisted of treatment with the flex-tine harrow before and after emergence in combination with chemical weed control at a reduced rate in 3-4 leave stage. The second one consisted of broadcast mechanical treatments before and after emergence followed by a final in-row application of herbicides and an inter-row cultivation at 6-7(8) leave stage. All trials were conducted on the Experimental farm of Bottelare HoGent-UGent on a sandy loam soil. Maize was growing in 1/3 crop rotation. The effect on weed growth as well as the economic impact of the different applications was evaluated. Combining chemical and mechanical weed control is a possible option in conventional farming but the disadvantages must be taken into account. A better planned weed control based on the real present weed-population in combination with a carefully thought-out choice of herbicides should also be considered as an IPM--approach. PMID:27145588

  20. Characterization and Comparison of Clavibacter michiganensis subsp. nebraskensis Strains Recovered from Epiphytic and Symptomatic Infections of Maize in Iowa

    PubMed Central

    Robertson, Alison E.

    2015-01-01

    Clavibacter michiganensis subsp. nebraskensis (Cmn), the causal organism of Goss’s wilt and leaf blight of maize, can be detected in the phyllosphere of its host prior to disease development. We compared the morphology and pathogenicity of 37 putative isolates of Cmn recovered from asymptomatic and symptomatic maize leaves. Thirty-three of the isolates produced mucoid orange colonies, irrespective of the source of isolation and all but four of these isolates were pathogenic on maize. The remaining 4 isolates recovered from asymptomatic leaves had large fluidal yellow colonies, and were non-pathogenic on maize. Isolates varied in their aggressiveness on a susceptible hybrid of maize but no significant differences in aggressiveness were detected between epiphytic isolates and those recovered from diseased maize tissues. The genomics of Cmn is poorly understood; therefore as a first step to determining what genes may play a role in virulence, we compared 33 putative virulence gene sequences from 6 pathogenic and a non-pathogenic isolate recovered from the phyllosphere. Sequence polymorphisms were detected in 5 genes, cellulase A, two endoglucanases, xylanase B and a pectate lyase but there was no relationship with pathogenicity. Further research is needed to determine what genes play a role in virulence of Cmn. Our data show however, that the virulence factors in Cmn likely differ from those reported for the closely related subspecies michiganensis and sepedonicus. PMID:26599211

  1. Wind Streaks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 12 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

    Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

    Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

    Image information: VIS instrument. Latitude 6.9, Longitude 69.4 East (290.6 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Preliminary Performance Measurements for a Streak Camera with a Large-Format Direct-Coupled CCD Readout

    SciTech Connect

    Lerche, R A; McDonald, J W; Griffith, R L; de Dios, G V; Andrews, D S; Huey, A W; Bell, P M; Landen, O L; Jaanimagi, P A; Boni, R

    2004-04-13

    Livermore's ICF Program has a large inventory of optical streak cameras built in the 1970s and 1980s. The cameras are still very functional, but difficult to maintain because many of their parts are obsolete including the original streak tube and image-intensifier tube. The University of Rochester's Laboratory for Laser Energetics is leading an effort to develop a fully automated, large-format streak camera that incorporates modern technology. Preliminary characterization of a prototype camera shows spatial resolution better than 20 lp/mm, temporal resolution of 12 ps, line-spread function of 40 {micro}m (fwhm), contrast transfer ratio (CTR) of 60% at 10 lp/mm, and system sensitivity of 16 CCD electrons per photoelectron. A dynamic range of 60 for a 2 ns window is determined from system noise, linearity and sensitivity measurements.

  3. Frequency-Domain Streak Camera and Tomography for Ultrafast Imaging of Evolving and Channeled Plasma Accelerator Structures

    NASA Astrophysics Data System (ADS)

    Li, Zhengyan; Zgadzaj, Rafal; Wang, Xiaoming; Reed, Stephen; Dong, Peng; Downer, Michael C.

    2010-11-01

    We demonstrate a prototype Frequency Domain Streak Camera (FDSC) that can capture the picosecond time evolution of the plasma accelerator structure in a single shot. In our prototype Frequency-Domain Streak Camera, a probe pulse propagates obliquely to a sub-picosecond pump pulse that creates an evolving nonlinear index "bubble" in fused silica glass, supplementing a conventional Frequency Domain Holographic (FDH) probe-reference pair that co-propagates with the "bubble". Frequency Domain Tomography (FDT) generalizes Frequency-Domain Streak Camera by probing the "bubble" from multiple angles and reconstructing its morphology and evolution using algorithms similar to those used in medical CAT scans. Multiplexing methods (Temporal Multiplexing and Angular Multiplexing) improve data storage and processing capability, demonstrating a compact Frequency Domain Tomography system with a single spectrometer.

  4. Picosecond-resolved X-ray absorption spectroscopy at low signal contrast using a hard X-ray streak camera

    SciTech Connect

    Adams, Bernhard W.; Rose-Petruck, Christoph; Jiao, Yishuo

    2015-06-24

    A picosecond-resolving hard-X-ray streak camera has been in operation for several years at Sector 7 of the Advanced Photon Source (APS). Several upgrades have been implemented over the past few years to optimize integration into the beamline, reduce the timing jitter, and improve the signal-to-noise ratio. These include the development of X-ray optics for focusing the X-rays into the sample and the entrance slit of the streak camera, and measures to minimize the amount of laser light needed to generate the deflection-voltage ramp. For the latter, the photoconductive switch generating the deflection ramp was replaced with microwave power electronics. With these, the streak camera operates routinely at 88 MHz repetition rate, thus making it compatible with all of the APS fill patterns including use of all the X-rays in the 324-bunch mode. Sample data are shown to demonstrate the performance.

  5. Effects of salts on the gelatinization and retrogradation properties of maize starch and waxy maize starch.

    PubMed

    Wang, Wei; Zhou, Hongxian; Yang, Hong; Zhao, Siming; Liu, Youming; Liu, Ru

    2017-01-01

    The objective of this study was to evaluate the effects of salts on the gelatinization and retrogradation of maize and waxy maize starch. Experimental results showed that the salting-out or structure-making ions, such as F(-) and SO4(2-), decreased the swelling power, solubility and transparency of both starches, but increased the gelatinization temperature, enthalpy, and syneresis, due to the tendency of these ions to protect the hydrogen bond links among starch molecules. On the other hand, the salting-in or structure-breaking ions, such as I(-) and SCN(-), exhibited the opposite effects. Microscopic observations confirmed such effects of salts on both starches. Furthermore, the effects of salts were more significant on waxy maize and on normal maize starch. Generally, salts could significantly influence on the gelatinization and retrogradation of maize and waxy maize starch, following the order of the Hofmeister series. PMID:27507481

  6. Foliar diseases of corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf blights and spots caused by fungi are some of the most destructive diseases of corn in the US and around the world. Correct identification of the disease is very important in determining the best means of control. For example, gray leaf spot of maize can be caused by one of at least two species...

  7. Nutrient absorbtion of weeds in maize.

    PubMed

    Lehoczky, E; Kismányoky, A; Nagy, P; Németh, T

    2008-01-01

    Our study was carried out in Hungary at Keszthely, in 2007. The effect of different cultivation methods: no-till drill, disk tillage, conventional tillage (ploughing) and five increasing N doses were studied on the weediness. The bi-factorial trial was arranged in split plot design with four replications. Crop rotation: winter wheat-winter wheat-maize-maize. The seeding of maize was 23rd of April in 2007. The weed survey was made with Balázs-Ujvárosi coenological method on the 17th of May. In the experiment were found 21 weed species. We collected all plants of every weed species by plots. The sample area was 1 m2. Furthermore five maize plants per plot were sampled on the 22nd of May. Maize was at 3-4 leaves stage. For reason of competition studies no herbicides were applied on sampling sites. The aerial parts of weeds and maize plants were collected, and the fresh and dry matter weight was measured. We analyzed in detail, the occurrence of weed species, and the biomass production of weeds in comparison with maize. The effect of different cultivation methods markedly demonstrated the weed cover, the number of perennial and annual weeds and the number of occurring weed species. PMID:19226848

  8. Antimicrobial activity of pyrrocidines from Acremonium zeae against endophytes and pathogens of maize.

    PubMed

    Wicklow, Donald T; Poling, Stephen M

    2009-01-01

    Acremonium zeae produces pyrrocidines A and B, which are polyketide-amino acid-derived antibiotics, and is recognized as a seedborne protective endophyte of maize which augments host defenses against microbial pathogens causing seedling blights and stalk rots. Pyrrocidine A displayed significant in vitro activity against Aspergillus flavus and Fusarium verticillioides in assays performed using conidia as inoculum, with pyrrocidine A being more active than B. In equivalent assays performed with conidia or hyphal cells as inoculum, pyrrocidine A revealed potent activity against major stalk and ear rot pathogens of maize, including F. graminearum, Nigrospora oryzae, Stenocarpella (Diplodia) maydis, and Rhizoctonia zeae. Pyrrocidine A displayed significant activity against seed-rotting saprophytes A. flavus and Eupenicillium ochrosalmoneum, as well as seed-infecting colonists of the phylloplane Alternaria alternata, Cladosporium cladosporioides, and Curvularia lunata, which produces a damaging leaf spot disease. Protective endophytes, including mycoparasites which grow asymptomatically within healthy maize tissues, show little sensitivity to pyrrocidines. Pyrrocidine A also exhibited potent activity against Clavibacter michiganense subsp. nebraskense, causal agent of Goss's bacterial wilt of maize, and Bacillus mojaviense and Pseudomonas fluorescens, maize endophytes applied as biocontrol agents, but were ineffective against the wilt-producing bacterium Pantoea stewartii. PMID:19055442

  9. Inhibition of polyamine oxidase activity affects tumor development during the maize-Ustilago maydis interaction.

    PubMed

    Jasso-Robles, Francisco Ignacio; Jiménez-Bremont, Juan Francisco; Becerra-Flora, Alicia; Juárez-Montiel, Margarita; Gonzalez, María Elisa; Pieckenstain, Fernando Luis; García de la Cruz, Ramón Fernando; Rodríguez-Kessler, Margarita

    2016-05-01

    Ustilago maydis is a biotrophic plant pathogenic fungus that leads to tumor development in the aerial tissues of its host, Zea mays. These tumors are the result of cell hypertrophy and hyperplasia, and are accompanied by the reprograming of primary and secondary metabolism of infected plants. Up to now, little is known regarding key plant actors and their role in tumor development during the interaction with U. maydis. Polyamines are small aliphatic amines that regulate plant growth, development and stress responses. In a previous study, we found substantial increases of polyamine levels in tumors. In the present work, we describe the maize polyamine oxidase (PAO) gene family, its contribution to hydrogen peroxide (H2O2) production and its possible role in tumor development induced by U. maydis. Histochemical analysis revealed that chlorotic lesions and maize tumors induced by U. maydis accumulate H2O2 to significant levels. Maize plants inoculated with U. maydis and treated with the PAO inhibitor 1,8-diaminooctane exhibit a notable reduction of H2O2 accumulation in infected tissues and a significant drop in PAO activity. This treatment also reduced disease symptoms in infected plants. Finally, among six maize PAO genes only the ZmPAO1, which encodes an extracellular enzyme, is up-regulated in tumors. Our data suggest that H2O2 produced through PA catabolism by ZmPAO1 plays an important role in tumor development during the maize-U. maydis interaction. PMID:26926794

  10. Production of highly concentrated, heat-stable hepatitis B surface antigen in maize.

    PubMed

    Hayden, Celine A; Egelkrout, Erin M; Moscoso, Alessa M; Enrique, Cristina; Keener, Todd K; Jimenez-Flores, Rafael; Wong, Jeffrey C; Howard, John A

    2012-10-01

    Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat-stable, oral alternative to parenterally administered commercial vaccines. Here, we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than fourfold higher than any previously reported lines. HBsAg expressed in maize seeds was extremely heat stable, tolerating temperatures up to 55 °C for 1 month without degradation. Optimal heat stability was achieved after oil extraction of ground maize material, either by supercritical fluid extraction or hexane treatment. The contributions of this material towards the development of a practical oral vaccine delivery system are discussed. PMID:22816734

  11. A multivariate regression model for detection of fumonisins content in maize from near infrared spectra.

    PubMed

    Giacomo, Della Riccia; Stefania, Del Zotto

    2013-12-15

    Fumonisins are mycotoxins produced by Fusarium species that commonly live in maize. Whereas fungi damage plants, fumonisins cause disease both to cattle breedings and human beings. Law limits set fumonisins tolerable daily intake with respect to several maize based feed and food. Chemical techniques assure the most reliable and accurate measurements, but they are expensive and time consuming. A method based on Near Infrared spectroscopy and multivariate statistical regression is described as a simpler, cheaper and faster alternative. We apply Partial Least Squares with full cross validation. Two models are described, having high correlation of calibration (0.995, 0.998) and of validation (0.908, 0.909), respectively. Description of observed phenomenon is accurate and overfitting is avoided. Screening of contaminated maize with respect to European legal limit of 4 mg kg(-1) should be assured. PMID:23993617

  12. Slit-mounted LED fiducial system for rotating mirror streak cameras

    SciTech Connect

    Shaw, L.L.; Muelder, S.A.; Rivera, A.T.

    1991-01-01

    We have developed a fiducial system for rotating mirror streak cameras that utilizes light emitting diodes mounted at the slit position of the camera. The diodes are driven to the required high brightness by a unique pulse power circuit designed to provide high voltage, high current pulses 18 nanoseconds in length at a frequency of up to 2.5 megahertz. The availability of super bright light emitting diodes with a wavelength of 630 to 640 nanometers allows us to record fiducial pulses, at streaking speeds in excess of 20mm per microsecond, on all the black and white films commonly used in high speed photography. The time marks on the film record are referenced to the real time of the experiment from a clock-driver that controls the start and frequency of the fiducial pulse train and by three adjustable and discreet blanked fiducials. This paper discusses the development of this system and describes the full setup as used at LLNL. 6 refs., 4 figs.

  13. Synchroscan streak camera imaging at a 15-MeV photoinjector with emittance exchange

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Ruan, J.; Thurman-Keup, R.

    2012-09-01

    At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a fast single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10-20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5 ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of ˜1 ps over 10 s of minutes. These steps allowed us to measure both the UV laser pulse train at 263 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 0.25-1 nC per micropulse. The phase-locked delay box allowed us to assess chromatic temporal effects and instigated another upgrade to an all-mirror input optics barrel. In addition, we added a slow sweep horizontal deflection plug-in unit to provide dual-sweep capability for the streak camera. We report on a series of measurements made during the commissioning of these upgrades including bunch-length and phase effects using the emittance exchange beamline and simultaneous imaging of a UV drive laser component, OTR, and the 800 nm diagnostics laser.

  14. An Optical Streak Diagnostic for Observing Anode-Cathode Plasmas for Radiographic Source Development

    SciTech Connect

    Droemer, Darryl W.; Crain, Marlon D.; Lare, Gregory A.; Bennett, Nichelle L.; Johnston, Mark D.

    2013-06-13

    National Security Technologies, LLC, and Sandia National Laboratories are collaborating in the development of pulsed power–driven flash x-ray radiographic sources that utilize high-intensity electron beam diodes. The RITS 6 (Radiographic Integrated Test Stand) accelerator at Sandia is used to drive a self magnetic pinch diode to produce a Bremsstrahlung x-ray source. The high electric fields and current densities associated with these short A-K gap pinch beam diodes present many challenges in diode development. Plasmas generated at both the anode and cathode affect the diode performance, which is manifested in varying spot (source) sizes, total dose output, and impedance profiles. Understanding the nature of these plasmas including closure rates and densities is important in modeling their behavior and providing insight into their mitigation. In this paper we describe a streak camera–based optical diagnostic that is capable of observing and measuring plasma evolution within the A-K gap. By imaging a region of interest onto the input slit of a streak camera, we are able to produce a time-resolved one-dimensional image of the evolving plasma. Typical data are presented.

  15. Nonlinear response of the photocathode of an x-ray streak camera to UV light

    SciTech Connect

    Kyrala, G.A.; Oro, D.M.; Studebaker, J.K.; Wood, W.M.; Schappert, G.T.; Watts, S.; Fulton, R.D.

    1994-09-01

    We have found that a potassium-iodide photocathode of an x-ray streak camera responds to UV light at {lambda}=308 nm. The photocathode surface work function, 6.5 eV, is larger than the 4 eV energy of the UV photon, hence the source of the response is interesting. We will present results on the response of a transmission type potassium-iodide photocathode to the UV light from a {lambda}308 nm, subpicosecond XeCl laser and from a {lambda}=326 nm HeCd laser. We will test for the nonlinearity of the yield to measure of the number of photons that are needed to be absorbed before a signal is recorded. We will present data on the effect of the UV irradiance on the yield, as well as on the temporal width of the recorded signal. We will give an explanation of the observation and its effect on the dynamic-range response of the streak-camera. We will show that the response is linear with the incident irradiance, up to an incident irradiance of 10{sup 8} W/cm{sup 2} and we will explain the observation.

  16. Automatic Reacquisition of Satellite Positions by Detecting Their Expected Streaks in Astronomical Images

    NASA Astrophysics Data System (ADS)

    Levesque, M.

    Artificial satellites, and particularly space junk, drift continuously from their known orbits. In the surveillance-of-space context, they must be observed frequently to ensure that the corresponding orbital parameter database entries are up-to-date. Autonomous ground-based optical systems are periodically tasked to observe these objects, calculate the difference between their predicted and real positions and update object orbital parameters. The real satellite positions are provided by the detection of the satellite streaks in the astronomical images specifically acquired for this purpose. This paper presents the image processing techniques used to detect and extract the satellite positions. The methodology includes several processing steps including: image background estimation and removal, star detection and removal, an iterative matched filter for streak detection, and finally false alarm rejection algorithms. This detection methodology is able to detect very faint objects. Simulated data were used to evaluate the methodology's performance and determine the sensitivity limits where the algorithm can perform detection without false alarm, which is essential to avoid corruption of the orbital parameter database.

  17. PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics

    SciTech Connect

    Garanin, S G; Bel'kov, S A; Rogozhnikov, G S; Rukavishnikov, N N; Romanov, V V; Voronich, I N; Vorob'ev, N S; Gornostaev, P B; Lozovoi, V I; Shchelev, M Ya

    2014-08-31

    A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 10{sup 3}) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 – 1.5 ps. (extreme light fields and their applications)

  18. Attosecond photoelectron streaking with enhanced energy resolution for small-bandgap materials.

    PubMed

    Guggenmos, Alexander; Akil, Ayman; Ossiander, Marcus; Schäffer, Martin; Azzeer, Abdallah Mohammed; Boehm, Gerhard; Amann, Markus-Christian; Kienberger, Reinhard; Schultze, Martin; Kleineberg, Ulf

    2016-08-15

    Attosecond photoelectron streaking spectroscopy allows time-resolved electron dynamics with a temporal resolution approaching the atomic unit of time. Studies have been performed in numerous systems, including atoms, molecules, and surfaces, and the quest for ever higher temporal resolution called for ever wider spectral extent of the attosecond pulses. For typical experiments relying on attosecond pulses with a duration of 200 as, the time-bandwidth limitation for a Gaussian pulse implies a minimal spectral bandwidth larger than 9 eV translating to a corresponding spread of the detected photoelectron kinetic energies. Here, by utilizing a specially tailored narrowband reflective XUV multilayer mirror, we explore experimentally the minimal spectral width compatible with attosecond time-resolved photoelectron spectroscopy while obtaining the highest possible spectral resolution. The validity of the concept is proven by recording attosecond electron streaking traces from the direct semiconductor gallium arsenide (GaAs), with a nominal bandgap of 1.42 eV at room temperature, proving the potential of the approach for tracking charge dynamics also in these technologically highly relevant materials that previously have been inaccessible to attosecond science. PMID:27519070

  19. Attosecond time-resolved streaked photoemission from Mg-covered W(110) surfaces

    NASA Astrophysics Data System (ADS)

    Liao, Qing; Thumm, Uwe

    2015-09-01

    We formulate a quantum-mechanical model for infrared-streaked photoelectron (PE) emission by ultrashort extreme ultraviolet (XUV) pulses from an adsorbate-covered metal surface, exposing the influence of microscopic PE dispersion in substrate and adsorbate on the interpretation of streaked photoemission spectra and photoemission time delays. We validate this numerical model first by reproducing measured relative photoemission delays (a) between valence-band and 2 p -core-level (CL) PEs emitted from clean Mg(0001) surfaces and (b) between conduction-band (CB) and 4 f -CL PEs from clean W(110) surfaces at two XUV-pulse central photon energies. Next, applying this model to ultrathin Mg adsorbate layers on W(110) substrates, we reproduce (i) the measured nonmonotonic dependence of relative photoemission delays between CB and Mg (2 p ) PEs and (ii) the monotonic dependence of relative delays between W (4 f ) and Mg (2 p ) PEs in a recent experiment [S. Neppl et al., Nature (London) 517, 342 (2015), 10.1038/nature14094].

  20. Single-shot visualization of evolving laser wakefields using an all-optical streak camera

    NASA Astrophysics Data System (ADS)

    Li, Zhengyan; Tsai, Hai-En; Zhang, Xi; Pai, Chih-Hao; Chang, Yen-Yu; Zgadzaj, Rafal; Wang, Xiaoming; Khudik, Vladimir; Shvets, Gennady; Downer, Michael

    2014-10-01

    We visualize ps-time-scale evolution of an electron density bubble, a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse, from the phase ``streak'' that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometry, reveal formation, propagation and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell (PIC) simulations validate the observed density-dependent bubble evolution, and correlate it with generation of a quasi-monoenergetic ~100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at plasma density ne ~2e19 cm-3, at which the bubble formed and persisted until the jet exit, enabling acceleration over a distance slightly exceeding the dephasing length. In contrast, at lower density, electrons accelerated inefficiently due to weak laser self-focusing and late bubble formation. At higher density, overly strong self-focusing also led to low quality electrons due to early bubble formation and strong dephasing. Bubble coalescence due to beam loading further degraded electron acceleration. This work was supported by DOE grants DESC0011617 and DE-SC0007889 and by the NSF-DOE Partnership in Plasma Science program.

  1. A Method for Analysing High Resolution, Time Domain, Streak Camera Calibration Data

    SciTech Connect

    Silbernagel, C

    2004-07-02

    Many experiments that require a highly accurate continuous time history of photon emission incorporate streak cameras into their setup. Nonlinear recordings both in time and spatial displacement are inherent to streak camera measurements. These nonlinearities can be attributed to sweep rate electronics, curvature of the electron optics, the magnification, and resolution of the electron optics. These nonlinearities are systematic; it has been shown that a short pulse laser source, an air-spaced etalon of known separation, and a defined spatial resolution mask can provide the proper image information to correct for the resulting distortion. A set of Interactive Data Language (IDL){sup 1} software routines were developed to take a series of calibration images showing temporally and spatially displaced points, and map these points from a nonlinear to a linear space-time resultant function. This correction function, in combination with standardized image correction techniques, can be applied to experiment data to minimize systematic errors and improve temporal and spatial resolution measurements.

  2. PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics

    NASA Astrophysics Data System (ADS)

    Garanin, S. G.; Bel'kov, S. A.; Rogozhnikov, G. S.; Rukavishnikov, N. N.; Romanov, V. V.; Voronich, I. N.; Vorob'ev, N. S.; Gornostaev, P. B.; Lozovoi, V. I.; Shchelev, M. Ya

    2014-08-01

    A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 103) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 - 1.5 ps.

  3. Gas-phase lifetimes of nucleobase analogues by picosecond pumpionization and streak techniques.

    PubMed

    Blaser, Susan; Frey, Hans-Martin; Heid, Cornelia G; Leutwyler, Samuel

    2014-01-01

    The picosecond (ps) timescale is relevant for the investigation of many molecular dynamical processes such as fluorescence, nonradiative relaxation, intramolecular vibrational relaxation, molecular rotation and intermolecular energy transfer, to name a few. While investigations of ultrafast (femtosecond) processes of biological molecules, e.g. nucleobases and their analogues in the gas phase are available, there are few investigations on the ps time scale. We have constructed a ps pump-ionization setup and a ps streak camera fluorescence apparatus for the determination of lifetimes of supersonic jet-cooled and isolated molecules and clusters. The ps pump-ionization setup was used to determine the lifetimes of the nucleobase analogue 2-aminopurine (2AP) and of two 2AP˙(H2O)n water cluster isomers with n=1 and 2. Their lifetimes lie between 150 ps and 3 ns and are strongly cluster-size dependent. The ps streak camera setup was used to determine accurate fluorescence lifetimes of the uracil analogue 2-pyridone (2PY), its self-dimer (2PY)2, two isomers of its trimer (2PY)3 and its tetramer (2PY)4, which lie in the 7-12 ns range. PMID:24983611

  4. Hardness methods for testing maize kernels.

    PubMed

    Fox, Glen; Manley, Marena

    2009-07-01

    Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect

  5. The dynamic nature and spectral characteristics of low-albedo slope streaks on Mars and their possible hydrologic implications

    NASA Astrophysics Data System (ADS)

    Mushkin, A.; Stillman, D. E.; Gillespie, A. R.; Montgomery, D. R.; Schreiber, B. C.; Hibbitts, C.

    2014-12-01

    Low-albedo down-slope streaks that form repeatedly within weekly time-scales and subsequently fade over seasonal to decadal periods are commonly observed in the tropical and mid-latitudes of Mars. 'Dry' mass-wasting processes vs. 'wet' modification of the surface by aqueous phases are the mechanisms typically considered to explain their formation. Recently, high frequency HiRISE image time-series of seasonal recurrence, incremental growth and fading of small (meter-decameter scale) slope streaks, also termed 'recurring slope lineae' (RSL), have been presented in support of a 'wet' origin likely associated with brine seepage. Here, we present new results that demonstrate comparable recurrence, incremental growth and fading characteristics over yearly time-scales for decameter-kilometer scale low-albedo slope-streaks in Lycus Sulci, Amazonis Planitia and Arabia Terra. These dynamic characteristics support the previous association of low-albedo slope streaks with brine seepage based on their geomorphic and spectral relations with surrounding unaffected slopes. Low-albedo slope streaks are typically not associated with detectable erosion or terminal, down-slope depositional activity at the resolution of 25 cm/pixel HiRISE images. CRISM observations consistently indicate that darkened slope-streak surfaces are spectrally enriched in FeOx and are void of detectable water/ice spectral absorption bands. Thus, the liquid seeps considered for the formation of meter to kilometer scale slope streaks are likely low-volume transient events that evaporate and/or freeze and sublime leaving behind a meta-stable dry precipitate that 'stains' the surface dark and may provide insights into the possible composition of such brines. Slope streak formation through a 'wet' brine seepage mechanism supports the possible presence of pressurized sub-surface aquifers that may be released via faults or cracks able to produce recurring transient discharge events during favorably warm daily

  6. [Effects of intercropping different crops with maize on the Cd uptake by maize].

    PubMed

    Li, Ning-Yu; Li, Zhi-An; Ding, Yong-Zhen; Zou, Bi; Zhuang, Ping

    2008-06-01

    A greenhouse experiment was conducted to investigate the effects of intercropping 7 kinds of crops on the Cd uptake by maize (Zea mays L.). The results showed that most intercrops had no significant effects on the growth of maize, only with purple haricot reduced the maize biomass by 32.2% of the control. Legume crops enhanced the total quantity of Cd in maize in a great magnitude, and chickpea worked most efficiently, which doubled the Cd quantity in maize. The 7 intercrops showed different capability of Cd uptake, among which, rape and amaranth absorbed larger amount of Cd, with a Cd level of 53.9 mg x kg(-1) and 51.0 mg x kg(-1) in their aboveground parts, respectively, and of 91.8 mg x kg(-1) in amaranth root when the soil Cd content was 3 mg x kg(-1) soil. There was an interaction between maize and intercrops in Cd uptake. Legumes absorbed smaller amount of Cd but significantly increased the Cd uptake by maize, while amaranth was in adverse. Rape had a higher level of Cd concentration in its shoot, but reduced the Cd in aboveground part of maize. It was indicated that if maize was used for phytoremediation of Cd-contaminated soil, a higher efficiency of Cd removal could be achieved by intercropping it with legumes. Rape and amaranth could be the two promising plants for phytoremediation because of their high Cd accumulation. PMID:18808034

  7. MaizeGDB: The Maize Model Organism Database for Basic, Translational, and Applied Research

    PubMed Central

    Lawrence, Carolyn J.; Harper, Lisa C.; Schaeffer, Mary L.; Sen, Taner Z.; Seigfried, Trent E.; Campbell, Darwin A.

    2008-01-01

    In 2001 maize became the number one production crop in the world with the Food and Agriculture Organization of the United Nations reporting over 614 million tonnes produced. Its success is due to the high productivity per acre in tandem with a wide variety of commercial uses. Not only is maize an excellent source of food, feed, and fuel, but also its by-products are used in the production of various commercial products. Maize's unparalleled success in agriculture stems from basic research, the outcomes of which drive breeding and product development. In order for basic, translational, and applied researchers to benefit from others' investigations, newly generated data must be made freely and easily accessible. MaizeGDB is the maize research community's central repository for genetics and genomics information. The overall goals of MaizeGDB are to facilitate access to the outcomes of maize research by integrating new maize data into the database and to support the maize research community by coordinating group activities. PMID:18769488

  8. Introgression of chromosome segments from multiple alien species in wheat breeding lines with wheat streak mosaic virus resistance.

    PubMed

    Ali, N; Heslop-Harrison, Js Pat; Ahmad, H; Graybosch, R A; Hein, G L; Schwarzacher, T

    2016-08-01

    Pyramiding of alien-derived Wheat streak mosaic virus (WSMV) resistance and resistance enhancing genes in wheat is a cost-effective and environmentally safe strategy for disease control. PCR-based markers and cytogenetic analysis with genomic in situ hybridisation were applied to identify alien chromatin in four genetically diverse populations of wheat (Triticum aestivum) lines incorporating chromosome segments from Thinopyrum intermedium and Secale cereale (rye). Out of 20 experimental lines, 10 carried Th. intermedium chromatin as T4DL*4Ai#2S translocations, while, unexpectedly, 7 lines were positive for alien chromatin (Th. intermedium or rye) on chromosome 1B. The newly described rye 1RS chromatin, transmitted from early in the pedigree, was associated with enhanced WSMV resistance. Under field conditions, the 1RS chromatin alone showed some resistance, while together with the Th. intermedium 4Ai#2S offered superior resistance to that demonstrated by the known resistant cultivar Mace. Most alien wheat lines carry whole chromosome arms, and it is notable that these lines showed intra-arm recombination within the 1BS arm. The translocation breakpoints between 1BS and alien chromatin fell in three categories: (i) at or near to the centromere, (ii) intercalary between markers UL-Thin5 and Xgwm1130 and (iii) towards the telomere between Xgwm0911 and Xbarc194. Labelled genomic Th. intermedium DNA hybridised to the rye 1RS chromatin under high stringency conditions, indicating the presence of shared tandem repeats among the cereals. The novel small alien fragments may explain the difficulty in developing well-adapted lines carrying Wsm1 despite improved tolerance to the virus. The results will facilitate directed chromosome engineering producing agronomically desirable WSMV-resistant germplasm. PMID:27245423

  9. Plant growth hormones suppress the development of Harpophora maydis, the cause of late wilt in maize.

    PubMed

    Degani, Ofir; Drori, Ran; Goldblat, Yuval

    2015-01-01

    Late wilt, a severe vascular disease of maize caused by the fungus Harpophora maydis, is characterized by rapid wilting of maize plants before tasseling and until shortly before maturity. The pathogen is currently controlled by resistant maize cultivars, but the disease is constantly spreading to new areas. The plant's late phenological stage at which the disease appears suggests that plant hormones may be involved in the pathogenesis. This work revealed that plant growth hormones, auxin (Indole-3-acetic acid) and cytokinin (kinetin), suppress H. maydis in culture media and in a detached root assay. Kinetin, and even more auxin, caused significant suppression of fungus spore germination. Gibberellic acid did not alter colony growth rate but had a signal suppressive effect on the pathogens' spore germination. In comparison, ethylene and jasmonic acid, plant senescing and defense response regulators, had minor effects on colony growth and spore germination rate. Their associate hormone, salicylic acid, had a moderate suppressive effect on spore germination and colony growth rate, and a strong influence when combined with auxin. Despite the anti-fungal auxin success in vitro, field experiments with dimethylamine salt of  2,4-dichlorophenoxyacetic acid (that mimics the influence of auxin) failed to suppress the late wilt. The lines of evidence presented here reveal the suppressive influence of the three growth hormones studied on fungal development and are important to encourage further and more in-depth examinations of this intriguing hormonal complex regulatory and its role in the maize-H. maydis interactions. PMID:25649030

  10. Rhizobium etli maize populations and their competitiveness for root colonization.

    PubMed

    Rosenblueth, Mónica; Martínez-Romero, Esperanza

    2004-05-01

    Rhizobium etli, which normally forms nitrogen-fixing nodules on Phaseolus vulgaris (common bean), is a natural maize endophyte. The genetic diversity of R. etli strains from bulk soil, bean nodules, the maize rhizosphere, the maize root, and inside stem tissue in traditional fields where maize is intercropped with P. vulgaris-beans was analyzed. Based on plasmid profiles and alloenzymes, it was determined that several R. etli types were preferentially encountered as putative maize endophytes. Some of these strains from maize were more competitive maize-root colonizers than other R. etli strains from the rhizosphere or from bean nodules. The dominant and highly competitive strain Ch24-10 was the most tolerant to 6-methoxy-2-benzoxazolinone (MBOA), a maize antimicrobial compound that is inhibitory to some bacteria and fungi. The R. tropici strain CIAT899, successfully used as inoculant of P. vulgaris, was also found to be a competitive maize endophyte in inoculation experiments. PMID:15024554

  11. Choosing a Genome Browser for a Model Organism Database (MOD): Surveying the Maize Community

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the maize genome sequencing is nearing its completion, the Maize Genetics and Genomics Database (MaizeGDB), the Model Organism Database for maize, integrated a genome browser to its already existing Web interface and database. The addition of the MaizeGDB Genome Browser to MaizeGDB will allow it ...

  12. Agriculture: Weather dilemma for African maize

    NASA Astrophysics Data System (ADS)

    Auffhammer, Maximilian

    2011-04-01

    The impact of climate change on food production remains uncertain, particularly in the tropics. Research that exploits the results of historical crop trials indicates that Africa's maize crop could be at risk of significant yield losses.

  13. Molecular Genetics of Mitochondrial Biogenesis in Maize.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mitochondrial genome encodes proteins essential for mitochondrial respiration and ATP synthesis. Nuclear gene products, however, are required for the expression of mitochondrial genes and the elaboration of functional mitochondrial protein complexes. We are exploiting a unique collection of maiz...

  14. Open chromatin reveals the functional maize genome

    PubMed Central

    Rodgers-Melnick, Eli; Vera, Daniel L.; Bass, Hank W.

    2016-01-01

    Cellular processes mediated through nuclear DNA must contend with chromatin. Chromatin structural assays can efficiently integrate information across diverse regulatory elements, revealing the functional noncoding genome. In this study, we use a differential nuclease sensitivity assay based on micrococcal nuclease (MNase) digestion to discover open chromatin regions in the maize genome. We find that maize MNase-hypersensitive (MNase HS) regions localize around active genes and within recombination hotspots, focusing biased gene conversion at their flanks. Although MNase HS regions map to less than 1% of the genome, they consistently explain a remarkably large amount (∼40%) of heritable phenotypic variance in diverse complex traits. MNase HS regions are therefore on par with coding sequences as annotations that demarcate the functional parts of the maize genome. These results imply that less than 3% of the maize genome (coding and MNase HS regions) may give rise to the overwhelming majority of phenotypic variation, greatly narrowing the scope of the functional genome. PMID:27185945

  15. Open chromatin reveals the functional maize genome.

    PubMed

    Rodgers-Melnick, Eli; Vera, Daniel L; Bass, Hank W; Buckler, Edward S

    2016-05-31

    Cellular processes mediated through nuclear DNA must contend with chromatin. Chromatin structural assays can efficiently integrate information across diverse regulatory elements, revealing the functional noncoding genome. In this study, we use a differential nuclease sensitivity assay based on micrococcal nuclease (MNase) digestion to discover open chromatin regions in the maize genome. We find that maize MNase-hypersensitive (MNase HS) regions localize around active genes and within recombination hotspots, focusing biased gene conversion at their flanks. Although MNase HS regions map to less than 1% of the genome, they consistently explain a remarkably large amount (∼40%) of heritable phenotypic variance in diverse complex traits. MNase HS regions are therefore on par with coding sequences as annotations that demarcate the functional parts of the maize genome. These results imply that less than 3% of the maize genome (coding and MNase HS regions) may give rise to the overwhelming majority of phenotypic variation, greatly narrowing the scope of the functional genome. PMID:27185945

  16. A European perspective on maize history.

    PubMed

    Tenaillon, Maud Irène; Charcosset, Alain

    2011-03-01

    Maize was domesticated at least 8700 years ago in the highlands of Mexico. Genome-wide studies have greatly contributed to shed light into the diffusion of maize through the Americas from its center of origin. Also the presence of two European introductions in southern and northern Europe is now established. Such a spread was accompanied by an extreme diversification, and adaptation to the long days and low temperatures of temperate climates has been a key step in maize evolution. Linkage mapping and association mapping have successfully led to the identification of a handful set of the genetic factors that have contributed to maize adaptation, opening the way to new discoveries. Ultimately, these alleles will contribute to sustain breeding efforts to meet the new challenges raised by the evolution of mankind. PMID:21377617

  17. [Effects of nitrogen management on maize nitrogen utilization and residual nitrate nitrogen in soil under maize/soybean and maize/sweet potato relay strip intercropping systems].

    PubMed

    Wang, Xiao-Chun; Yang, Wen-Yu; Deng, Xiao-Yan; Zhang, Qun; Yong, Tai-Wen; Liu, Wei-Guo; Yang, Feng; Mao, Shu-Ming

    2014-10-01

    A large amount of nitrogen (N) fertilizers poured into the fields severely pollute the environment. Reasonable application of N fertilizer has always been the research hotpot. The effects of N management on maize N utilization and residual nitrate N in soil under maize/soybean and maize/ sweet potato relay strip intercropping systems were reported in a field experiment in southwest China. It was found that maize N accumulation, N harvest index, N absorption efficiency, N contribution proportion after the anthesis stage in maize/soybean relay strip intercropping were increased by 6.1%, 5.4%, 4.3%, and 15.1% than under maize/sweet potato with an increase of 22.6% for maize yield after sustainable growing of maize/soybean intercropping system. Nitrate N accumulation in the 0-60 cm soil layer was 12.9% higher under maize/soybean intercropping than under maize/sweet potato intercropping. However, nitrate N concentration in the 60-120 cm soil layer when intercropped with soybean decreased by 10.3% than when intercropped with sweet potato, indicating a decrease of N leaching loss. Increasing of N application rate enhanced N accumulation of maize and decreased N use efficiency and significantly increased nitrate concentration in the soil profile except in the 60-100 cm soil layer, where no significant difference was observed with nitrogen application rate at 0 to 270 kg · hm(-2). Further application of N fertilizer significantly enhanced nitrate leaching loss. Postponing N application increased nitrate accumulation in the 60-100 cm soil layer. The results suggested that N application rates and ratio of base to top dressing had different influences on maize N concentration and nitrate N between maize/soybean and maize/sweet potato intercropping. Maize N concentration in the late growing stage, N harvest index and N use efficiency under maize/soybean intercropping increased (with N application rate at 180-270 kg · hm(-2) and ratio of base to top dressing = 3:2:5) and

  18. Can transgenic maize affect soil microbial communities?

    PubMed

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-09-29

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  19. Can Transgenic Maize Affect Soil Microbial Communities?

    PubMed Central

    Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

    2006-01-01

    The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short

  20. Analysis of Dark Slope Streaks on Mars based on Multitemporal HRSC Data

    NASA Astrophysics Data System (ADS)

    Schreiner, Björn; van Gasselt, Stephan; Jan-Peter, Muller

    2016-04-01

    Recurring slope lineae (RSL) on Mars are dark and narrow downhill oriented surface features found in equatorial regions (1) associated with water or hydrated salt flows (2). On the other hand there are Dark Slope Streaks which seem to be dry avalanches on dust covered slopes (3). The origin of both ist still under discussion. We found linear features in eastern Noctis Labyrinthus region (6°S, 265°E) with lengths of up to several kilometres and lateral extensions of 20-30 metres. As described by (4), RSL fade and recur in the same location over multiple Mars years. Similarily, Dark Slope Streaks form on at least annual to decade-long timescales (5). During 10 years of HRSC observation time (2005-2015) several linear features in Noctis Labyrinthus changed in visibility. Slope parameters and seasonal illumination conditions are investigated based on a digital elevation model derived from HRSC data. For large datasets a feature identification is presented which involves spatial filtering in conjunction with elevation data analysis. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n° 607379. (1) McEwen, A.S., et al. (2014): Recurring slope lineae in equatorial regions of Mars. Nat. Geosci 7: 53-58. (2) Ojha, L. et al. (2015): Spectral evidence for hydrated salts in recurring slope linear on Mars. Nat. Geosci, DOI:10.1038/NGEO2546. (3) Sullivan, R. et al. (2001). Mass Movement Slope Streaks Imaged by the Mars Orbiter Camera. J. Geophys. Res., 106(E10), 23,607-23,633. (4) McEwen, A.S., et al. (2011): Seasonal Flows on Warm Martian Slopes. Science, Vol. 333, Issue 6043, pp. 740-743. (5) Malin, M.C.; Edgett, K.S. (2001). Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission. J. Geophys. Res., 106(E10), 23,429-23,570.