APPLICATION OF SOMACLONAL VARIABILITY TO PRODUCTION OF FAST-GROWING TREES AS A RAW MATERIAL FOR BIOFUEL

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Voinikov V.K.

2012-08-01

Full Text Available Wood is one of the most widespread materials on the Earth. Wood raw materials may be used either to generate energy directly or to produce biofuel. The demand for sufficient amount of wood for these purposes necessitated establishment of arboreal plantations. Poplar тополь (Populus sp. is the most promising object to produce wood from plantations. In the last few years the Institute has been involved in the studies of potential of somaclonal variability in tissue cultivars to select plants with high growth indices. Berlin polar (P. × berolinensis, has been selected for this purpose, as its pyramid-shaped crown allows to place more plants on a plantation square area unit. It easily propagates by grafts and coppice shoots and is fairly resistant to leaf rust. Fast-growing trees may be acquired due to somaclonal variability and genetic transformation. In both cases an indispensable preliminary condition is a well-tested protocol of acquiring regenerates and their propagation in the cultivar of isolated tissues. Such a protocol has been worked out by now. It comprises the following phases: 1 isolation of stem tops in the first half of summer ant their sterilization; 2 cutting of explantates and their cultivation on the medium to induce regeneration; 3 propagation of regenerates on propagation medium; 4 elongation of regenerants; 5 rooting of regenerants; 6 acclimation and transfer of plants to the field for growth. At phases 3, 4 and 5 plants with desirable somaclonal changes are selected. Somaclonal varieties are selected on the basis of a large number of regenerants. For their further growth prior to planting on the Institute test site hydroponic units installed at the artificial climate station are used. This ensures equal conditions of nutrition and moisturizing for all the regenerants planted. Little plants cultivated in vitro, which are acquired at this stage of the work, will be further used for genetic transformation. A gene

RAPD analysis of colchicine induced variation of the Dendrobium ...

African Journals Online (AJOL)

STORAGESEVER

2009-04-20

Apr 20, 2009 ... species of the Dendrobium genera, and 13 orchids across generas. ... to detect variations at species level and among somaclonal variants in this study. ..... alternative for colchicines in in vitro choromosome doubling of Lilium.

Optimization of culture conditions (sucrose, pH, and photoperiod) for in vitro regeneration and early detection of somaclonal variation in ginger lime (Citrus assamensis).

Science.gov (United States)

Yaacob, Jamilah Syafawati; Mahmad, Noraini; Mat Taha, Rosna; Mohamed, Normadiha; Mad Yussof, Anis Idayu; Saleh, Azani

2014-01-01

Various explants (stem, leaf, and root) of Citrus assamensis were cultured on MS media supplemented with various combinations and concentrations (0.5-2.0 mg L(-1)) of NAA and BAP. Optimum shoot and root regeneration were obtained from stem cultures supplemented with 1.5 mg L(-1) NAA and 2.0 mg L(-1) BAP, respectively. Explant type affects the success of tissue culture of this species, whereby stem explants were observed to be the most responsive. Addition of 30 gL(-1) sucrose and pH of 5.8 was most optimum for in vitro regeneration of this species. Photoperiod of 16 hours of light and 8 hours of darkness was most optimum for shoot regeneration, but photoperiod of 24 hours of darkness was beneficial for production of callus. The morphology (macro and micro) and anatomy of in vivo and in vitro/ex vitro Citrus assamensis were also observed to elucidate any irregularities (or somaclonal variation) that may arise due to tissue culture protocols. Several minor micromorphological and anatomical differences were observed, possibly due to stress of tissue culture, but in vitro plantlets are expected to revert back to normal phenotype following full adaptation to the natural environment.

Investigation of the somaclonal and mutagen induced variability in barley by the application of protein and DNA markers

International Nuclear Information System (INIS)

Atanassov, A.; Todorovska, E.; Trifonova, A.; Petrova, M.; Marinova, E.; Gramatikova, M.; Valcheva, D.; Zaprianov, S.; Mersinkov, N.

1998-01-01

Barley, Hordeum vulgare L., is one of the most important crop species for Bulgaria. The characterisation of the genetic pool is of great necessity for the Bulgarian barley breeding programme which is directed toward improving quantitative and qualitative traits. Molecular markers [protein, restriction fragment length polymorphisms (RFLP) and randomly amplified polymorphic DNA (RAPD)] have been applied to characterise the Bulgarian barley cultivars and their regenerants. The changes in DNA loci coding for 26S, 5.8S and 18S rRNA repeats, C hordein locus and mitochondrial DNA organisation have been investigated. The potential for ribosomal DNA length polymorphism in Bulgarian barley cultivars appear to be limited to three different repeat lengths (10.2, 9.5 and 9.0kb) and three plant rDNA phenotypes. Polymorphism was not observed in ribosomal DNA repeat units in somaclonal variants. Variation concerning C hordein electrophoretic pattern was observed in one line from cultivar Jubiley. Analysis of the HorI locus reveals RFLPs in sequences coding for C hordeins in this line. Mitochondrial molecular markers are convenient for detection of DNA polymorphisms in the variant germplasm as well as for the somaclonal variants derived from it. Two lines from Ruen revealed polymorphic bands after hybridisation with mitochondrial DNA probe. RAPD assays have been carried out by using 20 different 10-mer primers. Heritable polymorphism in several tissue culture derived (TCD) lines was observed. RAPD assay is a sensitive and representative approach to distinguish the variability created by tissue culture and mutagenesis

Avaliação de variante somaclonal de porte baixo de bananeira 'Nanicão Jangada' (Musa sp em duas densidades Evaluation of a dwarf somaclonal variant of banana 'Nanicão Jangada' (Musa sp in two planting densities

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Patricia da Costa Zonetti

2003-12-01

Full Text Available Avaliou-se, sob duas densidades de plantio, um variante somaclonal de porte baixo de bananeira, comparando-o com a variedade Nanicão Jangada que lhe deu origem. Os materiais genéticos 'Nanicão Jangada'(controle e o variante somaclonal representado pelas seleções 224 e 225 de um ensaio anterior, foram avaliados nos espaçamentos 2,0m X 2,0m (densidade 2500 plantas ha-1 e 3,0m X 2,0m (1666plantas ha-1, na Fazenda de Ensino e Pesquisa da Faculdade de Engenharia - UNESP, Campus de Ilha Solteira-SP. O ensaio foi conduzido em blocos ao acaso com cinco repetições, com utilização de mudas micropropagadas, sob irrigação por gotejamento, no período de dezembro de 1998 a março de 2001, com avaliação dos dois primeiros ciclos de produção. Constatou-se efeito da densidade e do ciclo sobre a produção estimada de frutos sendo que no cultivo mais denso, a média foi de 81,25 t.ha-1 no primeiro ciclo de produção e 67,93 t.ha-1 no segundo ciclo. No cultivo de menor densidade a produção estimada no primeiro ciclo foi de 51,35 t.ha-1 e 44,08 t.ha-1 no segundo. As seleções do variante de porte baixo apresentaram menor altura da planta e mostraram-se relativamente mais precoces e com produção semelhante a cv. Nanicão Jangada no primeiro ciclo. No segundo ciclo houve uma queda na produção do bananal, com maior intensidade para a seleção 225 do variante.A dwarf somaclonal variant of banana was evaluated under two planting densities. It was compared with the cultivar "Nanicão Jangada", the original clone from which the variant derived. The genotypes 'Nanicão Jangada'(control and the somaclone, represented by selections 224 and 225 from a previous experiment, were evaluated at spaced 2.0 m X 2.0 m (density of 2500 plants ha-1 and 3.0 m X 2.0 m (1666 plants ha-1 at the "Fazenda de Ensino e Pesquisa da Faculdade de Engenharia - UNESP", Campus de Ilha Solteira, SP. The experiment was conducted in randomized complete blocks with 5

Detection of somaclonal variation in micropropagated Hibiscus ...

African Journals Online (AJOL)

The main objective of micropropagation is to produce clones i.e. plants which are phenotypically and genetically identical to the mother plants. The culture of organized meristems usually guarantees the production of true-to-type plants but variations in the progenies have been widely reported. Hibiscus sabdariffa L. plants ...

Comparative studies on cellular behaviour of carnation (Dianthus caryophyllus Linn. cv. Grenadin) grown in vivo and in vitro for early detection of somaclonal variation.

Science.gov (United States)

Yaacob, Jamilah Syafawati; Taha, Rosna Mat; Khorasani Esmaeili, Arash

2013-01-01

The present study deals with the cytological investigations on the meristematic root cells of carnation (Dianthus caryophyllus Linn.) grown in vivo and in vitro. Cellular parameters including the mitotic index (MI), chromosome count, ploidy level (nuclear DNA content), mean cell and nuclear areas, and cell doubling time (Cdt) were determined from the 2 mm root tip segments of this species. The MI value decreased when cells were transferred from in vivo to in vitro conditions, perhaps due to early adaptations of the cells to the in vitro environment. The mean chromosome number was generally stable (2n = 2x = 30) throughout the 6-month culture period, indicating no occurrence of early somaclonal variation. Following the transfer to the in vitro environment, a significant increase was recorded for mean cell and nuclear areas, from 26.59 ± 0.09  μm² to 35.66 ± 0.10  μm² and 142.90 ± 0.59  μm² to 165.05 ± 0.58  μm², respectively. However, the mean cell and nuclear areas of in vitro grown D. caryophyllus were unstable and fluctuated throughout the tissue culture period, possibly due to organogenesis or rhizogenesis. Ploidy level analysis revealed that D. caryophyllus root cells contained high percentage of polyploid cells when grown in vivo and maintained high throughout the 6-month culture period.

Use of AFLP marker system on sugarcane somaclones to study their resistance to rust

OpenAIRE

María Ileana Oloriz; Luis Rojas; Víctor Gil; Milady Mendoza; Ariel Arencibia; Elva Rosa Carmona; Elio Jiménez

2002-01-01

AFLPs (amplified fragment length polymorphism) was carried out from genomic DNA of five rust resistant sugar cane somaclons and their susceptible donor, Saccharum officinarum var B 4362, using three combinations of primers (EcoRI/aca: MseI/acc; EcoRI/aca: MseI/atg and EcoRI/aca: MseI/agg). Six polymorphic bands were obtained, two of these only appeared in the resistant genotypes, which are probably DNA sequences, related to rust resistance locus. These fragments have been cloned to study thei...

Identificação de variantes somaclonais em bananeiras 'Prata Anã', utilizando técnicas moleculares e citogenéticas Identification of somaclonal variants in 'Prata Anã' banana using molecular and cytogenetic techniques

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Nilson César Castanheira Guimarães

2009-04-01

Full Text Available Variação somaclonal é uma variação fenotípica de origem genética, ou seja, uma variação cromossômica que se torna herdável nas gerações seguintes, ou epigenética, que é uma variação transitória devido ao estresse fisiológico que o material sofre, quando submetido ao cultivo in vitro. Um problema específico envolvendo a variação somaclonal em bananeiras 'Prata Anã' foi observado em Andradas, Minas Gerais, em plantas oriundas de micropropagação. A maior dificuldade na separação dos indivíduos normais e variantes é que os caracteres morfológicos, que são inerentes a este tipo de variação, só se tornam evidentes quando a planta está adulta, o que impossibilita a eliminação dos indivíduos variantes ainda em viveiro. Com o objetivo de identificar, ainda em viveiro aqueles indivíduos variantes somaclonais, técnicas moleculares (RAPD e SSR e citogenéticas (contagem cromossômica e citometria de fluxo foram utilizadas. Cento e três primers RAPD, 11 combinações de dois primers RAPD, e 33 pares de primers SSR foram utilizados na tentativa de se encontrar marcadores polimórficos capazes de distinguir os indivíduos normais dos variantes, além de distinguir bananeiras 'Prata Anã' de 'Prata'. O primer OPW-08 gerou um fragmento polimórfico que distinguiu uma planta variante de todas as demais, provando que a variação não ocorre de maneira uniforme no genoma dos indivíduos variantes e que não há um retorno à cultivar Prata. As análises com marcadores SSR e a contagem cromossômica não possibilitaram a distinção dos indivíduos variantes, nem a separação das cultivares Prata e Prata Anã. As análises de citometria de fluxo evidenciaram a grande instabilidade cromossômica das bananeiras, porém elas não foram eficientes na identificação de variantes somaclonais.Somaclonal variation is a phenotypical variation of genetic origin, that is, a chromosomal variation that becomes inheritable in the

Use of AFLP marker system on sugarcane somaclones to study their resistance to rust

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María Ileana Oloriz

2002-10-01

Full Text Available AFLPs (amplified fragment length polymorphism was carried out from genomic DNA of five rust resistant sugar cane somaclons and their susceptible donor, Saccharum officinarum var B 4362, using three combinations of primers (EcoRI/aca: MseI/acc; EcoRI/aca: MseI/atg and EcoRI/aca: MseI/agg. Six polymorphic bands were obtained, two of these only appeared in the resistant genotypes, which are probably DNA sequences, related to rust resistance locus. These fragments have been cloned to study their nucleotide sequence and to investigate their roll in resistance mechanism develop by these mutants during Puccinia melanocephala infection. Key words: molecular markers, Puccinia. melanocephala, Saccharum

The effects of gamma-ray irradiation to strawberry (Fragaria x ananassa Duch.) calli on shoot regeneration, achene formation and morphological variations of regenerants

International Nuclear Information System (INIS)

Kasumi, Masakazu

2002-01-01

Strawberry (Fragaria x ananassa 'Nyoho') calli, derived from anthers, were irradiated with gamma -ray at dosages from 100 to 1,600 Gy (10 Gy · hr - 1) and their effects on callus growth, plant regeneration, and somaclonal variation were analyzed. The growth of callus and percentage of plant regeneration from the callus were reduced slightly at dosages less than 200 Gy, moderately at 400 Gy, and markedly above 800 Gy. Fruit growth associated with seed fertility (>50 % ) was morphologically normal at less than 100 Gy, whereas achene formation was significantly inhibited above 200 Gy. The percentages of morphological variation in regenerants formed from the irradiated callus were:13.7 (no irradiation), 18.6 (100 Gy), 66.0 (200 Gy), 75.7 (400 Gy), and 97.0 (800 Gy). Furthermore, higher dosages yielded wider variations, e.g., thick and small leaf, light leaf color, white flesh, and long fruit. In some regenerants, more than one morphological aberrations developed, some of which were transmissible to daughter plants. These results revealed that the irradiating strawberry callus with gamma - ray resulted in a higher degree and wider spectrum of somaclonal variation than did simple callus culture. (author)

Physiological responses of somaclonal variants of triploid bermudagrass (Cynodon transvaalensis x Cynodon dactylon) to drought stress.

Science.gov (United States)

Lu, Shaoyun; Chen, Chuanhao; Wang, Zhongcheng; Guo, Zhenfei; Li, Haihang

2009-03-01

Eight somaclonal variants with enhanced drought tolerance were isolated from regenerated plants of triploid bermudagrass (Cynodon dactylon x Cynodon transvaalensis cv., TifEagle). Three of them (10-17, 89-02, 117-08) with strong drought tolerance were selected for investigations of physiological responses to drought stress. Compared to the parent control, TifEagle, the somaclonal variants had higher relative water contents and relative growth, and lower ion leakages in the greenhouse tests, while no difference in evapotranspirational water losses and soil water contents was observed between the variants and TifEagle. The variants also had less leaf firing in the field tests under drought stress. Superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities decreased gradually in responses to drought stress in all plants and exhibited negative correlations with ion leakage, indicating that the declined activities of these antioxidant enzymes were associated with drought injury in the triploid bermudagrass. However, CAT activities were significantly higher in all three variants than in TifEagle during drought stress. Two variants, 10-17 and 89-02, also had significantly higher APX activities than TifEagle before and during the first 4 days of drought treatments. These two lines also showed higher SOD activities after prolonged drought stress. Proline, total soluble sugars and sucrose were accumulated under drought stress in all plants and exhibited positive correlations with ion leakage. More proline and sugars were accumulated in TifEagle than in the variants. The results indicated that higher activities of the antioxidant enzymes in the variants during drought stress are associated with their increased drought tolerance.

Novel Prunus rootstock somaclonal variants with divergent ability to tolerate waterlogging.

Science.gov (United States)

Pistelli, Laura; Iacona, Calogero; Miano, Dario; Cirilli, Marco; Colao, Maria Chiara; Mensuali-Sodi, Anna; Muleo, Rosario

2012-03-01

Plants require access to free water for nutrient uptake, but excess water surrounding the roots can be injurious or even lethal because it blocks the transfer of free oxygen between the soil and the atmosphere. Genetic improvement efforts in this study were focused on the increased tolerance in roots to waterlogging. Among a pool of clones generated in vitro from leaf explants of rootstock Mr.S.2/5 of Prunus cerasifera L., the S.4 clone was flood tolerant whereas the S.1 clone was sensitive. The S.4 clone formed adventitious roots on exposure to flooding. Moreover, the chlorophyll content and mitochondrial activity in the leaf and root, soluble sugar content, alcohol dehydrogenase activity and ethylene content were different between the clones. The sorbitol transporter gene (SOT1) was up-regulated during hypoxia, the alcohol dehydrogenase genes (ADH1 and ADH3) were up-regulated in the leaves and down-regulated in the roots of the S.4 clone during hypoxia, and the 1-aminocyclopropane-1-oxidase gene (ACO1) was up-regulated in the leaves and roots of the S.4 clone during hypoxia and down-regulated in the wild-type roots. In addition, in the S.4 root, hypoxia induced significant down-regulation of a glycosyltransferase-like gene (GTL), which has a yet-undefined role. Although the relevant variation in the S.4 genome has yet to be determined, genetic alteration clearly conferred a flooding-tolerant phenotype. The isolation of novel somaclonals with the same genomic background but with divergent tolerance to flooding may offer new insights in the elucidation of the genetic machinery of resistance to flooding and aid in the selection of new Prunus rootstocks to be used in various adverse environments.

GENETIC VARIABILITY OF CULTURED PLANT TISSUES UNDER NORMAL CONDITIONS AND UNDER STRESS

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Dolgikh Yu.I.

2012-08-01

Full Text Available The genetic variability induced by in vitro conditions known as somaclonal variation is of practical interest due to its potential uses in plant breeding but, on the other hand, if clonal propagation or transformation is main goal, it becomes an unwelcome phenomenon. Thus, it is important to know frequency, the genomic distribution, the mechanisms and factors influencing somaclonal variation. We studied variability of PCR-based DNA markers of cultured tissues and regenerated plants of maize and bread wheat. The original A188 line of maize and the somaclones obtained were tested using 38 RAPD and 10 ISSR primers. None of the A188 plants showed variation in the RAPD and ISSR spectra for any of the primers used. However, the PCR spectra obtained from the somaclones demonstrated some variations, i.e., 22 RAPD primers and 6 ISSR primers differentiated at least one somaclonal variant from the progenitor line. Six SCAR markers were developed based on several RAPD and ISSR fragments. The inheritance of these SCAR markers was verified in the selfing progeny of each somaclone in the R1–R4 generations and in the hybrids, with A188 as the parental line in the F1 and F2 generations. These markers were sequenced and bioinformatic searches were performed to understand the molecular events that may underlie the variability observed in the somaclones. All changes were found in noncoding sequences and were induced by different molecular events, such as the insertion of long terminal repeat transposon, precise miniature inverted repeat transposable element (MITE excision, microdeletion, recombination, and a change in the pool of mitochondrial DNA. In two groups of independently produced somaclones, the same features (morphological, molecular were variable, which confirms the theory of ‘hot spots’ occurring in the genome. The presence of the same molecular markers in the somaclones and in different non-somaclonal maize variants suggests that in some cases

Regenerant arabidopsis lineages display a distinct genome-wide spectrum of mutations conferring variant phenotypes

KAUST Repository

Jiang, Caifu

2011-07-28

Multicellular organisms can be regenerated from totipotent differentiated somatic cell or nuclear founders [1-3]. Organisms regenerated from clonally related isogenic founders might a priori have been expected to be phenotypically invariant. However, clonal regenerant animals display variant phenotypes caused by defective epigenetic reprogramming of gene expression [2], and clonal regenerant plants exhibit poorly understood heritable phenotypic ("somaclonal") variation [4-7]. Here we show that somaclonal variation in regenerant Arabidopsis lineages is associated with genome-wide elevation in DNA sequence mutation rate. We also show that regenerant mutations comprise a distinctive molecular spectrum of base substitutions, insertions, and deletions that probably results from decreased DNA repair fidelity. Finally, we show that while regenerant base substitutions are a likely major genetic cause of the somaclonal variation of regenerant Arabidopsis lineages, transposon movement is unlikely to contribute substantially to that variation. We conclude that the phenotypic variation of regenerant plants, unlike that of regenerant animals, is substantially due to DNA sequence mutation. 2011 Elsevier Ltd. All rights reserved.

Regenerant arabidopsis lineages display a distinct genome-wide spectrum of mutations conferring variant phenotypes

KAUST Repository

Jiang, Caifu; Mithani, Aziz; Gan, Xiangchao; Belfield, Eric J.; Klingler, John  P.; Zhu, Jian-Kang; Ragoussis, Jiannis; Mott, Richard; Harberd, Nicholas  P.

2011-01-01

Multicellular organisms can be regenerated from totipotent differentiated somatic cell or nuclear founders [1-3]. Organisms regenerated from clonally related isogenic founders might a priori have been expected to be phenotypically invariant. However, clonal regenerant animals display variant phenotypes caused by defective epigenetic reprogramming of gene expression [2], and clonal regenerant plants exhibit poorly understood heritable phenotypic ("somaclonal") variation [4-7]. Here we show that somaclonal variation in regenerant Arabidopsis lineages is associated with genome-wide elevation in DNA sequence mutation rate. We also show that regenerant mutations comprise a distinctive molecular spectrum of base substitutions, insertions, and deletions that probably results from decreased DNA repair fidelity. Finally, we show that while regenerant base substitutions are a likely major genetic cause of the somaclonal variation of regenerant Arabidopsis lineages, transposon movement is unlikely to contribute substantially to that variation. We conclude that the phenotypic variation of regenerant plants, unlike that of regenerant animals, is substantially due to DNA sequence mutation. 2011 Elsevier Ltd. All rights reserved.

Características morfoanatômicas da epiderme foliar de plantas variantes e não variantes somaclonais de bananeiras (Musa sp. Colla cv. Prata-anã cultivadas in vitro Morphoanatomical characteristics of the leaf epidermis of variant plants and somaclonal non-variants of banana trees (Musa sp. Colla cv. Prata-anã cultivated in vitro

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Guilherme Araújo Lacerda

2008-03-01

Full Text Available A variação somaclonal corresponde ao aparecimento de plantas anormais durante o processo de multiplicação in vitro, principalmente relacionada à estatura, no caso o gigantismo. O objetivo deste trabalho foi averiguar as diferenças morfoanatômicas da epiderme foliar na tentativa de diferenciar as plantas de 'Prata-anã' em relação aos seus variantes somaclonais. A análise por microscopia eletrônica de varredura mostrou uma diferença significativa entre o diâmetro polar dos estômatos da 'Prata-anã' não variante e suas variantes, ambas em condições in vitro, observando-se que o mesmo não ocorre para as plantas in vivo. O número médio de estômatos é menor nas plantas variantes somaclonais, porém sem diferenças significativas a não ser para a planta PIII. A descamação de cera é evidente somente nas plantas variantes de ambos os materiais (in vitro e in vivo. Conclui-se que os caracteres morfoanatômicos da epiderme foliar, como densidade estomática, diâmetro estomático polar e a uniformidade da cera atuam como marcadores morfológicos para caracterizar as plantas micropropagadas de 'Prata-anã' em relação aos seus variantes somaclonais para a característica gigantismo.Somaclonal variation corresponds to the emergence of abnormal plants during the process of multiplication in vitro, mainly related to stature, in the case the gigantism. The aim of this work was to discover morphoanatomical differences of the leaf epidermis in an attempt to differentiate plants of "Prata-anã" from their somaclonal variants. Analysis by scanning electronic microscopy showed significant difference between the polar diameter of the stomata of the "Prata-anã" non-variant and its variants, both in vitro. The same does not happen for plants in vivo. The average number of stomata is lower in the somaclonal variant plants, but without significant differences except for plant PIII. Wax peeling is only evident in the variant plants of both the

In vitro selection of salinity tolerant variants from triploid bermudagrass (Cynodon transvaalensis x C. dactylon) and their physiological responses to salt and drought stress.

Science.gov (United States)

Lu, Shaoyun; Peng, Xinxiang; Guo, Zhenfei; Zhang, Gengyun; Wang, Zhongcheng; Wang, Congying; Pang, Chaoshu; Fan, Zhen; Wang, Jihua

2007-08-01

A protocol was established for in vitro selection of salinity tolerant somaclonal variations from suspension cultured calli of triploid bermudagrass cv. TifEagle. To induce somaclonal variations the calli were subcultured for 18 months and were then subject to three-round selections for salt-tolerant calli by placing on solid medium containing 0.3 M NaCl for 10 days followed by a recovery for 2 weeks. The surviving calli were regenerated on regeneration medium containing 0.1 M NaCl. Three somaclonal variant lines (2, 71, and 77) were obtained and analyzed. The selected somaclonal lines showed higher relative growth and less injury than TifEagle under salt stress, indicating that they increased salt tolerance. In addition, they had higher relative water content and lower electrolyte leakage than TifEagle after withholding irrigation, indicating that they also increased drought tolerance. The three somaclonal variant lines had higher proline content than TifEagle under normal growth condition. The line 71 had a higher K(+)/Na(+) ratio, whereas the lines 2 and 77 had higher CAT activity under control and salt stress conditions, indicating that different mechanisms for salt tolerance might exist in these three lines.

Field performance of Populus expressing somaclonal variation in resistance to Septoria musiva

Science.gov (United States)

M. E. Ostry; K. T. Ward

2003-01-01

Over 1500 trees from two hybrid poplar clones regenerated from tissue culture and expressing somatic variation in leaf disease resistance in a laboratory leaf disk bioassay were field-tested for 5-11 years to examine their resistance to Septoria leaf spot and canker and to assess their growth characteristics compared with the source clones....

Physiological differences and changes in global DNA methylation levels in Agave angustifolia Haw. albino variant somaclones during the micropropagation process.

Science.gov (United States)

Duarte-Aké, Fátima; Castillo-Castro, Eduardo; Pool, Felipe Barredo; Espadas, Francisco; Santamaría, Jorge M; Robert, Manuel L; De-la-Peña, Clelia

2016-12-01

Global DNA methylation changes caused by in vitro conditions are associated with the subculturing and phenotypic variation in Agave angustifolia Haw. While the relationship between the development of albinism and in vitro culture is well documented, the role of epigenetic processes in this development leaves some important questions unanswered. During the micropropagation of Agave angustifolia Haw., we found three different phenotypes, green (G), variegated (V) and albino (A). To understand the physiological and epigenetic differences among the somaclones, we analyzed several morphophysiological parameters and changes in the DNA methylation patterns in the three phenotypes during their in vitro development. We found that under in vitro conditions, the V plantlets maintained their CAM photosynthetic capacity, while the A variant showed no pigments and lost its CAM photosynthetic ability. Epigenetic analysis revealed that global DNA methylation increased in the G phenotype during the first two subcultures. However, after that time, DNA methylation levels declined. This hypomethylation correlated with the appearance of V shoots in the G plantlets. A similar correlation occurred in the V phenotype, where an increase of 2 % in the global DNA methylation levels was correlated with the generation of A shoots in the V plantlets. This suggests that an "epigenetic stress memory" during in vitro conditions causes a chromatin shift that favors the generation of variegated and albino shoots.

Plant genetics poised to revolutionize agriculture

Energy Technology Data Exchange (ETDEWEB)

Sharp, W.R.; Evans, D.A.; Ammirato, P.V.

1984-05-01

The biotechnology tools of somaclonal variation, gametoclonal variation, protoplast fusion technology and clonal propagation offer a shorter fuse than recombinant DNA technology for development of new plant varieties fine-tuned for industrial and consumer agricultural products. DNA Plant Technology Corporation (DNAP) has an aggressive somaclonal variation program for development of tomato varieties. Gametoclonal variation has commercial opportunities for some cereals such as wheat and rice. Protoplast fusion technology has greatest application to crops such as tobacco, tomato, potato, carrot, rapeseed, lettuce and alfalfa. Clonal propagation is especially useful in root and tuber crops and is currently providing the means for large scale propagation and mechanical delivery systems.

Assessment of somaclonal variation in sugarcane

African Journals Online (AJOL)

admin

2012-10-30

Oct 30, 2012 ... and Mee, 1969; Nagai et al., 1986) and chromosome number (Sreenivasan and Jalaja, 1982; ... for sexual improvement through tissue culture. The somatic chromosome number of this variety is 2n = 108. .... rearrangements in repetitive sequences might be the reason for the difference between the control ...

Regeneracion adventicia de somaclones de uchuva (Physalis peruviana

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Santana Gloria E.

1997-06-01

Full Text Available

Hipocoti1os de uchuva (Physalis peruvjana L. fueron utilizados en la inducción de callos y regeneración de plántulas. El medio basal de Murashige y Skoog (MS fue suplementado con bencil amino purina (BAP de 0 a 5,0 ppm, acido giberelico (GA₃ 0 Y 1,0 ppm en combinacion con acido naftalenoacetico (ANA de 0 a 1.0 ppm o con acido 2,4 diclorofenoxiacetico (2,4-D  de 0 a 1.0 ppm. La inducción de callos dependió de las interacciones hormonales y condiciones de luz. La regeneración de plántulas en medias que contenían ANA o cuando el medio no fue suplementado  con 2,4-D fue nula o muy poca. EI mayor numero de plántulas regeneradas fue observado en medios complementados con 1.0 ppm de BAP, 1,0 ppm de GA y 0,5 ppm de 2,4-D en condiciones de luz. Las plántulas regeneradas fueron micropropagadas en el medio basal de MS sin ningún suplemento hormonal. Finalmente, las plantas se evaluaron in vitro bajo condiciones de heladas simuladas.

Palabras claves: Variaci6n somaclonal, inducción de callos morfogénesis indirecta, cultivo in vitro.

Selection of wheat lines with resistance to Fusarium graminearum by somaclonal variation

International Nuclear Information System (INIS)

Sun Guangzu

1997-10-01

The screening wheat new lines which have the resistance to Fusarium graminearum were completed by in vitro induced mutation and cell screening. Four new lines with resistance to Fusarium graminearum were obtained. The field inoculating determination in 1990∼1996 showed that their resistance was 1∼2 degree higher than that of parents, and there were variations in main agronomic traits between the new lines and their parents. Changes of the defensive enzymes (SOD, POD), sugar-protein on cell surface, and ultrastructure were investigated by using new lines and their parents under the action of toxin of Fusarium graminearum. The new lines under the action of toxin of Fusarium graminearum have the ability to increase the defensive enzyme activity and thickness of sugarprotein on cell surface and to reduce the damage of cell membrane system that would result in resistance increasing. (8 refs., 3 figs., 3 tabs.)

Gamma irradiation-induced variation in carrots (Daucus carota L.)

International Nuclear Information System (INIS)

Al-Safadi, B.; Simon, P.W.

1996-01-01

Carrot tissue cultures, germinating seed, and dry seed were exposed to gamma radiation. Irradiation accelerated germination of carrot seed in the M1 generation at low doses (0.5 and 1 krad), whereas higher doses delayed germination. A high negative correlation was observed between dose and survival of plants after seed irradiation. Plant size and root weight were 20% to 35% greater than control plants after seeds, but not tissue cultures, were exposed to low doses of gamma irradiation. Higher doses reduced M1 plant size by 50% in germinating seed and tissue culture treatments but less for the dry seed treatment. Seed production decreased while phenotypic variation of M1 plants increased with increasing gamma ray dosage. Root weight and total dissolved solids were highly variable in M2 families. Less variation was observed in total carotene content and none was seen in sugar type (reducing vs. non reducing sugars). Induced variation in root color and root shape was also observed. Irradiation of germinating seed and tissue cultures yielded more M2 variation than irradiation of dry seed. Putative point mutations were not observed. Unirradiated carrot tissue cultures did not yield significant M2 somaclonal variation. Average root weight of M2 plants increased with increasing gamma ray dosage, especially for the dry seed treatment

Gamma irradiation induced variation in carrots (Daucus Carota L.)

International Nuclear Information System (INIS)

Al-Safady, B.; Simon, P.W.

1999-01-01

Carrot tissue cultures, germinating seed, and dry seed were exposed to gamma radiation. Irradiation accelerated germination of carrot seed in the M 1 generation at low doses (0.5 and 1 krad), whereas higher doses delayed germination. A high negative correlation was observed between dose and survival of plants after seed irradiation. Plant size and root weight were 20% to 35% greater than control plants after seeds, but not tissue culture, were exposed to low doses of gamma irradiation. Higher doses reduced M 1 plant size by > 50% in germinating seed and tissue culture treatments but less for the dry seed treatment. Seed production decreased while phenotypic variation of M 1 plants increased with increasing gamma ray dosage. Root weight and total dissolved solids were highly variable in M 2 families. Less variation was observed in total carotene content and none was seen in sugar type [reducing vs. non reducing sugars]. Induced variation in root color and rot shape was also observed. Irradiation of germinating seed and tissue cultures yielded more M 2 variation than irradiation of dry seed. Putative point mutations were not observed. Unirradiated carrot tissue cultures did not yield significant M 2 somaclonal variation. Average root weight of M 2 plants increased with increasing gamma ray dosage, especially for the dry seed treatment (Author)

Meristem micropropagation of cassava (Manihot esculenta) evokes genome-wide changes in DNA methylation

OpenAIRE

Shedrack Reuben Kitimu; Shedrack Reuben Kitimu; Julian eTaylor; Timothy J March; Fred eTairo; Mike J Wilkinson; Carlos Marcelino Rodriguez Lopez

2015-01-01

There is great interest in the phenotypic, genetic and epigenetic changes associated with plant in vitro culture known as somaclonal variation. In vitro propagation systems that are based on the use of microcuttings or meristem cultures are considered analogous to clonal cuttings and so widely viewed to be largely free from such somaclonal effects. In this study, we surveyed for epigenetic changes during propagation by meristem culture and by field cuttings in five cassava (Manihot esculenta...

Detection of somaclonal variation in micropropagated Hibiscus ...

African Journals Online (AJOL)

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Paper Accepted on 26 July 2010. Abstract. The main ... micropropagated propagules of ornamental pineapple (Santos et al., 2008) and in cucumber ... fleshy calyces are used for wine making, juice, jam, jelly, syrup, gelatin, pudding, ice cream ...

Regeneration ability and genetic transformation of root type chicory ...

African Journals Online (AJOL)

This simple, efficient and reproducible protocol could be useful for inducing somaclonal variation and genetic modification of root chicory cultivars to broaden genetic variation and transferring of important genes. Keywords: Chicory, regeneration, transformation, 1-Naphthaleneacetic acid (NAA), indole-3-acetic acid (IAA), ...

Somaclonal variation associated with oil palm (Elaeis guineensis ...

African Journals Online (AJOL)

aghomotsegin

2014-02-26

Feb 26, 2014 ... Malaysia and Indonesia together accounting for around. 83% of world palm oil production in 2001 (Wahid et al.,. 2004). The oil palm is an important economic crop, producing food and raw materials for the food, confectionary, cosmetics and ... inherently very slow, and high heterogeneity is still observed ...

Evaluation of Sugarcane (Saccharum officinarum L. Somaclonals Tolerance to Salinity Via In Vitro and In Vivo

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HAMID RAJABI MEMARI

2011-06-01

Full Text Available Tissue culture technique was used to obtain salt tolerant variants from embryogenic calluses of sugarcane (Saccharum sp. var. CP48-103 that cultured on a selective medium containing different levels of NaCl (0, 0.2, 0.4, 0.6, and 0.8% NaCl. A total of four plants regenerated from the tolerant calluses were selected but the best of them in vigor grown in in vitro and hydroponic systems under salinity stress to comparison with source variety. With increasing supply of NaCl in both systems, root growth was more adversely affected than was shoot growth. Chlorophyll contents showed a decreasing trend and dry matter yield of plants reduced but in a slow rate in tolerant somaclonal than source variety. The biochemical analysis showed that at high salt concentration, Cl- and Na+ content in shoot and root increased. With rising salt concentration from 0 to 0.8%, content of Cl- in shoot and root of tolerant variant changed lower than parent showed that this variant had genetic lowest ratio of shoot/root chloride and had minimum transport of Cl- to shoots. Also this variant had high content of Ca2+ in shoot and high K+/Na+ ratio at all salinity levels. Thus it probably has genetic potential to avoid harmful ions uptake.

Progressive erosion of genetic and epigenetic variation in callus-derived cocoa (Theobroma cacao) plants.

Science.gov (United States)

Rodríguez López, Carlos M; Wetten, Andrew C; Wilkinson, Michael J

2010-06-01

*Relatively little is known about the timing of genetic and epigenetic forms of somaclonal variation arising from callus growth. We surveyed for both types of change in cocoa (Theobroma cacao) plants regenerated from calli of various ages, and also between tissues from the source trees. *For genetic change, we used 15 single sequence repeat (SSR) markers from four source trees and from 233 regenerated plants. For epigenetic change, we used 386 methylation-sensitive amplified polymorphism (MSAP) markers on leaf and explant (staminode) DNA from two source trees and on leaf DNA from 114 regenerants. *Genetic variation within source trees was limited to one slippage mutation in one leaf. Regenerants were far more variable, with 35% exhibiting at least one mutation. Genetic variation initially accumulated with culture age but subsequently declined. MSAP (epigenetic) profiles diverged between leaf and staminode samples from source trees. Multivariate analysis revealed that leaves from regenerants occupied intermediate eigenspace between leaves and staminodes of source plants but became progressively more similar to source tree leaves with culture age. *Statistical analysis confirmed this rather counterintuitive finding that leaves of 'late regenerants' exhibited significantly less genetic and epigenetic divergence from source leaves than those exposed to short periods of callus growth.

Field evaluation of regenerated plants by somatic embryogenesis from shoots apexes of axillary buds in ´Navolean’ (Musa spp., AAB.

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Jorge López

2005-04-01

Full Text Available The use of shoots apexes from axilary buds for callus induction with embryogenic structures in plantain ‘Navolean’ (Group AAB permitted to develop a plant regeneration method through out somatic embryogenesis. In order to know the phenotypic variants that may be produced with the previously mentioned method , 1000 plants were planted in field conditions in comparison to those coming from somatic embryos obtained from multibuds as initial explants and organogenesis-derived plants (shoot tipsand conventionally derived plants (corms, during two growing cycles. The main morphological characters and yield components were evaluated. The total frequency of somaclonal variation during the first growing cycle in plants coming from somatic embryos obtained from shoots apexes from axilary buds as initial explants were 1.1%, and 8,6% in regenerated plants from somatic embryos obtained from multi-buds as initial explants. Later, in this same growing cycle, plants regenerated from somatic embryos (both sources showed a similar performance between them and they were significantly superior in all evaluated variants in comparison to corm-derived plants. In the second growing cycle, significant differences were not observed in yield components of suckers from evaluated plants, in spite of the propagation method used. With regard to somaclonal variation, the best performance was obtained with shoots apexes from axilary buds as explants. Finally, the feasibility of using the new method was shown. Key words: embryogenic cell suspensions, somaclonal variation

Elimination of Grapevine leafroll associated virus-3, Grapevine rupestris stem pitting associated virus and Grapevine virus A from a Tunisian Cultivar by Somatic Embryogenesis and Characterization of the Somaclones Using Ampelographic Descriptors.

Science.gov (United States)

Bouamama-Gzara, Badra; Selmi, Ilhem; Chebil, Samir; Melki, Imene; Mliki, Ahmed; Ghorbel, Abdelwahed; Carra, Angela; Carimi, Francesco; Mahfoudhi, Naima

2017-12-01

Prospecting of local grapevine ( Vitis vinifera L.) germplasm revealed that Tunisia possesses a rich patrimony which presents diversified organoleptic characteristics. However, viral diseases seriously affect all local grapevine cultivars which risk a complete extinction. Sanitation programs need to be established to preserve and exploit, as a gene pool, the Tunisian vineyards areas. The presence of the Grapevine leafroll associated virus-3 (GLRaV-3), Grapevine stem pitting associated virus (GRSPaV) and Grapevine virus A (GVA), were confirmed in a Tunisian grapevine cultivar using serological and molecular analyses. The association between GRSPaV and GVA viruses induces more rugose wood symptoms and damages. For this reason the cleansing of the infected cultivar is highly advisable. Direct and recurrent somatic embryos of cv. 'Hencha' were successfully induced from filament, when cultured on Chée and Pool (1987). based-medium, enriched with 2 mg 1 -1 of 2,4-dichlorophenoxyacetic acid and 2.5 mg 1 -1 of Thidiazuron, after 36 weeks of culture. After six months of acclimatization, RT-PCR carried on 50 somaplants confirmed the absence of GVA, GRSPa-V as well as GLRaV-3 viruses in all somaplants. Ampelographic analysis, based on eight OIV descriptors, was carried out on two years acclimated somaplants, compared to the mother plant. Results demonstrated that the shape and contours of 46 somaclones leaves are identical to mother plant leaves and four phenotypically off-type plants were observed. The healthy state of 100% 'Hencha' somaclones and the high percentage of phenotypically true-to-type plants demonstrate that somatic embryogenesis is a promising technique to adopt for grapevine viruses elimination.

Elimination of Grapevine leafroll associated virus-3, Grapevine rupestris stem pitting associated virus and Grapevine virus A from a Tunisian Cultivar by Somatic Embryogenesis and Characterization of the Somaclones Using Ampelographic Descriptors

Directory of Open Access Journals (Sweden)

Badra Bouamama-Gzara

2017-12-01

Full Text Available Prospecting of local grapevine (Vitis vinifera L. germplasm revealed that Tunisia possesses a rich patrimony which presents diversified organoleptic characteristics. However, viral diseases seriously affect all local grapevine cultivars which risk a complete extinction. Sanitation programs need to be established to preserve and exploit, as a gene pool, the Tunisian vineyards areas. The presence of the Grapevine leafroll associated virus-3 (GLRaV-3, Grapevine stem pitting associated virus (GRSPaV and Grapevine virus A (GVA, were confirmed in a Tunisian grapevine cultivar using serological and molecular analyses. The association between GRSPaV and GVA viruses induces more rugose wood symptoms and damages. For this reason the cleansing of the infected cultivar is highly advisable. Direct and recurrent somatic embryos of cv. ‘Hencha’ were successfully induced from filament, when cultured on Chée and Pool (1987. based-medium, enriched with 2 mg 1−1 of 2,4-dichlorophenoxyacetic acid and 2.5 mg 1−1 of Thidiazuron, after 36 weeks of culture. After six months of acclimatization, RT-PCR carried on 50 somaplants confirmed the absence of GVA, GRSPa-V as well as GLRaV-3 viruses in all somaplants. Ampelographic analysis, based on eight OIV descriptors, was carried out on two years acclimated somaplants, compared to the mother plant. Results demonstrated that the shape and contours of 46 somaclones leaves are identical to mother plant leaves and four phenotypically off-type plants were observed. The healthy state of 100% ‘Hencha’ somaclones and the high percentage of phenotypically true-to-type plants demonstrate that somatic embryogenesis is a promising technique to adopt for grapevine viruses elimination.

Feeding the world with induced mutations and biotechnology

International Nuclear Information System (INIS)

Mohan Jain, S.

2002-01-01

The paper discussed the following subjects: biotechnology - somaclonal variation, somatic embryogenesis, somatic cell hybridization; induced mutations - in banana, ornamental plants; in vitro mutagenesis; T-DNA insertional mutagenesis. Suggestions for improving biotechnology in the developing countries also presented in the paper

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African Journals Online (AJOL)

ACSS

2014-08-22

Aug 22, 2014 ... Printed in Uganda. All rights reserved ..... somaclonal variation and survival rate in soil of. 90%. In other ... higher auxin supply and thus needed higher TDZ .... The study was funded by the World Bank and ... Australia. Lichter ...

Gamma greenhouse for chronic irradiation in plant mutation breeding

International Nuclear Information System (INIS)

Azhar Mohamad; Rusli Ibrahim; Sobri Hussein

2009-01-01

The gamma greenhouse makes use of chronic irradiation from a 137 Cs source (double encapsulated 800 Ci caesium-137 pencil) producing a low dose rate, which is considered to be more effective in recovering and producing useful mutants in comparison to acute irradiation. The irradiation facility comprises an open topped irradiation area 30 m in diameter, protected by a partial concrete wall with entry maze and site topography. For safety, the facility is protected by a sophisticated interlock system, which only allows the source to be exposed when all the prerequisite safety conditions are met, and automatically returns the source to the safe storage position if any safety device is compromised. The main irradiation area is further protected by a 300 m diameter exclusion zone that is also protected by the safety interlock circuit. The facility can accommodate a wide range of plant materials such as seeds, seedlings in pots, cuttings, callus, somatic embryos and suspension cell cultures. Plant samples will be exposed to low dose gamma radiation over long periods of time (hours, weeks, months), depending on their nature and sensitivity. There was evidence whereby exposure of tissue culture materials to continuous low dose gamma irradiation resulting in considerably elevated somaclonal variation frequency without negative effects on culture response. It is not surprising that in vitro culture generating somaclonal variation together with in vitro mutagenesis inducing mutation lead to a higher variation frequency due to possible addition of mutagenic effect by in vitro mutagenesis to somaclonal variability arising from in vitro culture as well as the interaction between them. (Author)

Regeneration of multiple shoots from transgenic potato events facilitates the recovery of phenotypically normal lines: assessing a cry9Aa2 gene conferring insect resistance

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Jacobs Jeanne ME

2011-10-01

Full Text Available Abstract Background The recovery of high performing transgenic lines in clonal crops is limited by the occurrence of somaclonal variation during the tissue culture phase of transformation. This is usually circumvented by developing large populations of transgenic lines, each derived from the first shoot to regenerate from each transformation event. This study investigates a new strategy of assessing multiple shoots independently regenerated from different transformed cell colonies of potato (Solanum tuberosum L.. Results A modified cry9Aa2 gene, under the transcriptional control of the CaMV 35S promoter, was transformed into four potato cultivars using Agrobacterium-mediated gene transfer using a nptII gene conferring kanamycin resistance as a selectable marker gene. Following gene transfer, 291 transgenic lines were grown in greenhouse experiments to assess somaclonal variation and resistance to potato tuber moth (PTM, Phthorimaea operculella (Zeller. Independently regenerated lines were recovered from many transformed cell colonies and Southern analysis confirmed whether they were derived from the same transformed cell. Multiple lines regenerated from the same transformed cell exhibited a similar response to PTM, but frequently exhibited a markedly different spectrum of somaclonal variation. Conclusions A new strategy for the genetic improvement of clonal crops involves the regeneration and evaluation of multiple shoots from each transformation event to facilitate the recovery of phenotypically normal transgenic lines. Most importantly, regenerated lines exhibiting the phenotypic appearance most similar to the parental cultivar are not necessarily derived from the first shoot regenerated from a transformed cell colony, but can frequently be a later regeneration event.

Exploitation de la variabilité somaclonale pour la recherche d'oeillet (Dianthus caryophyllus L. tolérant à la salinité

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Haouala, F.

2003-01-01

Full Text Available Exploitation of Somaclonal Variability for Research of Carnation (Dianthus caryophyllus L. Tolerant to Salinity. Callogenesis in carnation (Dianthus caryophyllus L. 'Légion d'Honneur' is possible from internodes in a medium containing 0.1 mg.l-1 NAA and 0.1 mg.l-1 TDZ. Regeneration from callus needs 2 mg.l-1 BA. Shoots rooting is obtained on a medium containing 0.5 mg.l-1 IBA. Callus growth is reduced and regeneration rate is very affected in presence of NaCl 100 mM. Shoot rooting is better without NaCl. Regenerated plants present somaclonal variation and those obtained under salt stress have a better relative tolerance to salinity than plants regenerated without salt.

An assessment of genetic fidelity of in vitro grown plantlets of rose ...

African Journals Online (AJOL)

A simple and routine method for the analysis of somaclonal variation among tissue culture derived rose plants is a prerequisite for precise monitoring of quality control during rapid mass micropropagation. Random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) molecular marker techniques ...

Micropropagation, genetic engineering, and molecular biology of Populus

Science.gov (United States)

N. B. Klopfenstein; Y. W. Chun; M. -S. Kim; M. A. Ahuja; M. C. Dillon; R. C. Carman; L. G. Eskew

1997-01-01

Thirty-four Populus biotechnology chapters, written by 85 authors, are comprised in 5 sections: 1) in vitro culture (micropropagation, somatic embryogenesis, protoplasts, somaclonal variation, and germplasm preservation); 2) transformation and foreign gene expression; 3) molecular biology (molecular/genetic characterization); 4) biotic and abiotic resistance (disease,...

Potential role of biotechnology tools for genetic improvement of “lost ...

African Journals Online (AJOL)

The paper considers the potential role of biotechnology applications like DNA markers in understanding the evolution, origin, distribution and diversity of fonio in Africa; somaclonal variation in generating genetic variability in fonio; and genetic transformation in circumventing fonio breeding barriers to introduce alien genes ...

Plant cell engineering: current research, application and future prospects

International Nuclear Information System (INIS)

Wang Xunqing; Liu Luxiang

2008-01-01

This paper reviewed the current status of basic research in plant cell engineering, highlighted the application of embryo culture, double haploid (DH) technology, protoplast culture and somatic hybridization, somaclonal variation, rapid propagation, and bio-products production of plant-origin, and t he prospects. (authors)

A review of somaclonal variation in plantain (Musa spp ...

African Journals Online (AJOL)

SARAH

2013-07-30

Jul 30, 2013 ... Plant tissue has contributed immensely in large-scale production of resistant and pest free plantlets, .... Potato is a native of South America (Peru) where considerable ..... An efficient, short and cost-effective regeneration ...

Use of protoplast, cell, and shoot tip culture in an elm germ plasm improvement program

Science.gov (United States)

R. Daniel Lineberger; M.B. Sticklen; P.M. Pijut; Mark A. Kroggel; C.V.M. Fink; S.C. Domir

1990-01-01

An elm germplasm improvement program was established using three distinct approaches: (1) development of protoplast regeneration protocols with the goal of attempting somatic hybridization between Ulmus americana and disease resistant hybrids; (2) evaluation of the extent of somaclonal variation in plants regenerated from protoplasts; and (3)...

Regeneration and molecular analysis of date palm ( Phoenix ...

African Journals Online (AJOL)

Clonal plants of date palm (Poenix dactylifera L.) were regenerated from juvenile leaves on regimes consisting of the use of 2,4-D. Success depended on the concentrations of 2,4-D tested. The cultures produced adventitious shoot buds directly at the basal part of leaves as well as excessive calli. Somaclonal variation in ...

Plant Regeneration and Cellular Behaviour Studies in Celosia cristata Grown In Vivo and In Vitro

Science.gov (United States)

Taha, Rosna Mat; Wafa, Sharifah Nurashikin

2012-01-01

Tissue culture studies of Celosia cristata were established from various explants and the effects of various hormones on morphogenesis of this species were examined. It was found that complete plant regeneration occurred at highest percentage on MS medium supplemented with 2.0 mg/L NAA and 1.5 mg/L BAP, with the best response showed by shoot explants. In vitro flowering was observed on MS basal medium after six weeks. The occurrence of somaclonal variation and changes in cellular behavior from in vivo and in vitro grown plants were investigated through cytological studies and image analysis. It was observed that Mitotic Index (MI), mean chromosome numbers, and mean nuclear to cell area ratio of in vitro root meristem cells were slightly higher compared to in vivo values. However, in vitro plants produced lower mean cell areas but higher nuclear areas when compared to in vivo plants. Thus, no occurrence of somaclonal variation was detected, and this was supported by morphological features of the in vitro plants. PMID:22593677

SELECCIÓN Y REGENERACIÓN in vitro DE SOMACLONES DE TOMATE DE ÁRBOL (Solanum betacea cav. Sendt UTILIZANDO FILTRADOS DE CULTIVO DE Colletotrichum acutatum CON ACTIVIDAD PECTINASA SELECTION AND in vitro REGENERATION OF SOMACLONES OF TREE TOMATO (Solanum betacea cav. Sendt USING CULTURE FILTRATES OF Colletotrichum acutatum WITH PECTINASA ACTIVITY

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Carlos Patiño Torres

2007-12-01

Full Text Available Se utilizaron filtrados de cultivo de Colletotrichum acutatum, agente causal de la antracnosis del tomate de árbol, para la selección in vitro de variantes somaclonales de ésta planta con resistencia potencial a la enfermedad. El filtrado, utilizado a varias concentraciones, demostró ser un agente de selección efectivo cuando se integró al medio de cultivo, pues causó niveles elevados de mortalidad de los explantes comparado con los tratamientos sin filtrado. Igualmente, se estudió el efecto de la benziladenina (BA ó BAP sobre la respuesta organogénica de explantes de tejido foliar de tomate de árbol.Culture filtrates of Colletotrichum acutatum, causal agent of the anthracnose disease in tree tomato, were used for the in vitro selection of somaclonal variants with potential resistance to this disease. Culture filtrates used at different concentrations, showed to be an effective agent of selection when they were mixed with the growth media. The findings indicated a high level of mortality for the explants growing on the ammended media as compared with these growing on non ammended one. The effect of the benziladenina (BA ó BAP on the organogenic response of leaf explants of tomato tree was also studied.

Somaclonal variation in hybrid poplars for resistance to Septoria leaf spot

Science.gov (United States)

M.E. Ostry; D. D. Skilling

1987-01-01

Tissue culture techniques have been used to obtain hybrid poplars with putative resistance to leaf spot caused by Septoria musiva from clones previously susceptible to the disease. Stem internode explants were used to obtain proliferating callus cultures. Adventitious bud formation and shoot proliferation were then induced. Elongated shoots were excised and rooted in a...

DNA fingerprinting of sugarcane for detecting molecular evidence of somaclonal variation

International Nuclear Information System (INIS)

Ramos Leal, M.; Canales, E.; Michel, R.; Coto, O.; Cornide, M.T.

1998-01-01

Molecular characterisation of eight sugarcane mutants which tolerate 1% NaCl, was performed by means of restriction fragment length polymorphism (RFLP) analysis at the genomic level, using a group of molecular probes for ribosomal DNAs and two others, Δ-pyrroline-5-carboxylate reductase (ΔP5CR) and ATPase, probably related to salinity stress tolerance. Results showed the molecular evidence of genetic changes in comparison to the susceptible donor variety and the possible presence of more that one mechanism to tolerate salt stress. (author)

Optimization of an Efficient Non-Tissue Culture Transformation Method for Brassica Juncea

International Nuclear Information System (INIS)

Naeem, I.; Munir, I.; Iqbal, A.; Ullah, F.

2016-01-01

The major hurdles in successful in vitro transformation of Brassica juncea through standard tissue culture (STC) method are: culture contamination, somaclonal variations, and lack of expertise. Moreover, the current STC method is time consuming and needs continuous electricity. In the present study, the in planta transformation method through floral dip with or without vacuum infiltration was optimized for successful transformation of B. juncea. The B. juncea CV RAYA Anmol was used for transformation through Agrobacterium tumefaciens strain GV3101 harboring the binary vector plasmid pBinGlyBar4-EADcT. Based on the resistance reaction to the herbicide Basta, 20 and 40 resistant seedlings were obtained from 2000 seed germinated from the plants transformed through floral dip and vacuum infiltration methods, respectively. The PCR analyses further confirmed the presence of transgene in 3 floral dipped plants without vacuum infiltration and 17 floral dipped plants with vacuum infiltration, giving the transformation frequencies of 1.5*10/sup -3/ and 8.5*10/sup -3/, respectively. This method, which avoids tissue culture, will reduce the somaclonal variation accompanying prolonged culture of cells in a dedifferentiated state, will facilitate functional genomics and improvement of Brassica juncea with novel desirable traits while reducing time and expense. (author)

Assessment of genetic and epigenetic changes in virus-free garlic (Allium sativum L.) plants obtained by meristem culture followed by in vitro propagation.

Science.gov (United States)

Gimenez, Magalí Diana; Yañez-Santos, Anahí Mara; Paz, Rosalía Cristina; Quiroga, Mariana Paola; Marfil, Carlos Federico; Conci, Vilma Cecilia; García-Lampasona, Sandra Claudia

2016-01-01

This is the first report assessing epigenetic variation in garlic. High genetic and epigenetic polymorphism during in vitro culture was detected.Sequencing of MSAP fragments revealed homology with ESTs. Garlic (Allium sativum) is a worldwide crop of economic importance susceptible to viral infections that can cause significant yield losses. Meristem tissue culture is the most employed method to sanitize elite cultivars.Often the virus-free garlic plants obtained are multiplied in vitro (micro propagation). However, it was reported that micro-propagation frequently produces somaclonal variation at the phenotypic level, which is an undesirable trait when breeders are seeking to maintain varietal stability. We employed amplification fragment length polymorphism and methylation sensitive amplified polymorphism (MSAP) methodologies to assess genetic and epigenetic modifications in two culture systems: virus-free plants obtained by meristem culture followed by in vitro multiplication and field culture. Our results suggest that garlic exhibits genetic and epigenetic polymorphism under field growing conditions. However, during in vitro culture system both kinds of polymorphisms intensify indicating that this system induces somaclonal variation. Furthermore, while genetic changes accumulated along the time of in vitro culture, epigenetic polymorphism reached the major variation at 6 months and then stabilize, being demethylation and CG methylation the principal conversions.Cloning and sequencing differentially methylated MSAP fragments allowed us to identify coding and unknown sequences of A. sativum, including sequences belonging to LTR Gypsy retrotransposons. Together, our results highlight that main changes occur in the initial 6 months of micro propagation. For the best of our knowledge, this is the first report on epigenetic assessment in garlic.

Tobacco clones derived from tissue culture with supersensitivity to ozone

International Nuclear Information System (INIS)

Sun, E.J.; Kang, H.W.

2003-01-01

New tobacco clones supersensitive to ozone were obtained from tissue culture. - At least two supersensitive tobacco somaclones were obtained from tissue culture (TC) , when this approach was used to asexually propagate Bel-W3 tobacco indicator plants. These somaclones can detect as low as 30 ppb ozone for a 4-h exposure duration both within CSTR exposure chambers and in ambient air. Comparison of the injury index and their coefficient of variance showed that the TC plantlets usually have more uniform performance in response to ozone in addition to their higher sensitivity. A quick regeneration procedure was established to preserve the supersensitive germplasm immediately when it was found. The TC plantlets will flower and produce seed similar to seed-grown tobacco. The TC approach proved to be a better propagation system for valuable indicator plant species. The mechanism that causes the variation and the possible difference in their genome from seed-grown tobacco is still unknown. Further studies are needed in the future to determine if factors in the TC system may be responsible for the sensitivity difference

The examination of Hevea brasiliensis plants produced by in vitro culture and mutagenesis by DNA fingerprinting techniques

International Nuclear Information System (INIS)

Low, F.C.; Atan, S.; Jaafar, H.

1998-01-01

Rubber (Hevea brasiliensis) plants derived from anther and ovule culture as well as gamma-irradiated plants were examined by several DNA marker techniques. These include restriction fragment length polymorphisms (RFLPs), random amplified polymorphic DNA (RAPD), sequence tagged microsatellite sites (STMS), DNA amplification fingerprinting (DAF) and amplified fragment length polymorphisms (AFLPs). Compared to control plants produced by vegetative propagation (cutting and budding), plants produced by in vitro culture appeared to have a reduction in the number of rDNA loci. Two RAPD protocols were compared and found to be similar in amplification of the major DNA bands. After confirmation that the RAPD method adopted was reproducible, the technique was applied to the present studies. Eight out of the 60 primers screened were able to elicit polymorphisms between pooled DNA from in vitro culture plants. Variations in DNA patterns were observed between pooled DNA samples of anther-derived plants as well as between anther-derived and ovule-derived plants. Comparisons of RAPD patterns obtained between anther-derived plants exposed to increasing dosages of gamma-irradiation with non irradiated anther-derived plants revealed distinct DNA polymorphisms. The changes in DNA profiles did not appear to be correlated to the dosage of irradiation. Since somaclonal variation was detected, it was difficult to identify changes which were specifically caused by irradiation. Application of the STMS technique to tag micro satellite sequences (GA) n , (TA) n and (TTA) n in the hydroxymethylglutaryl coenzyme A reductase-1 (hmgr-1) gene failed to detect differences between plants derived from anther and ovule culture. Although restriction endonuclease digestions with methylation sensitive enzymes suggested that four in vitro culture plants examined exhibited similar digestion patterns as the controls, a change in cytosine methylation in one anther-derived plant was detected. Examination of

Effect of X-Rays on Growth Rate of Rose Shoot Cultures and the Ability of Isolated Protoplasts to Form Cell Colonies

International Nuclear Information System (INIS)

Moustafa, R. A. K.

2004-01-01

The popularity of rose as a garden plant, allied with its use in the production of cut flowers and also as a source of aromatic rose oils, make it one of the most important ornamental crops. Roses, however, have suffered from a narrow genetic base to which only few species have contributed significantly. In vitro culture of plants might facilitate the improvement of rose via the exploitation of somaclonal variation to generate new genetic variability and selection within the variation for desirable traits. The application of mutagens for in vitro cultures, in addition to the induced mutations, may lead to increase the somaclonal variation, thus providing additional variation for selection. On the other hand, plant protoplasts offer exciting possibilities to establish in vitro selection programs based on single cells. Induced variation in isolated protoplasts using mutagen agents may be one mean to select useful mutants. Thus the present experiments were conducted to determine the effect of X-rays on shoot cultures and the isolated protoplasts of rose (Rosa sp.). The materials consisted of the three rose varieties Rosa wichuriana, Paricer charm and Heckenzauber.The applied doses were 0, 10, 20, 30, 40, 50 and 60 Gy. Obtained results indicated that the genotypes differed in their sensitivity to X-rays. Rosa wichuriana seemed to be the most sensitive variety to radiation, where a dose of 20 Gy caused approximately 50% reduction in growth rate of shoot cultures, while the same dose decreased the growth rate of Paricer charm only by 25% and did not affect the growth of Heckenzauber. Results also revealed that the ability of irradiated protoplasts to form cell colonies increased when a dose of 10 Gy was performed. Doses higher than that level caused gradual decreasing in the forming of cell colonies, but however, the protoplasts could form colonies even when a dose of 60 Gy was applied. (Author)

Effect of Cryopreservation and Post-Cryopreservation Somatic Embryogenesis on the Epigenetic Fidelity of Cocoa (Theobroma cacao L.).

Science.gov (United States)

Adu-Gyamfi, Raphael; Wetten, Andy; Marcelino Rodríguez López, Carlos

2016-01-01

While cocoa plants regenerated from cryopreserved somatic embryos can demonstrate high levels of phenotypic variability, little is known about the sources of the observed variability. Previous studies have shown that the encapsulation-dehydration cryopreservation methodology imposes no significant extra mutational load since embryos carrying high levels of genetic variability are selected against during protracted culture. Also, the use of secondary rather than primary somatic embryos has been shown to further reduce the incidence of genetic somaclonal variation. Here, the effect of in vitro conservation, cryopreservation and post-cryopreservation generation of somatic embryos on the appearance of epigenetic somaclonal variation were comparatively assessed. To achieve this we compared the epigenetic profiles, generated using Methylation Sensitive Amplified Polymorphisms, of leaves collected from the ortet tree and from cocoa somatic embryos derived from three in vitro conditions: somatic embryos, somatic embryos cryopreserved in liquid nitrogen and somatic embryos generated from cryoproserved somatic embryos. Somatic embryos accumulated epigenetic changes but these were less extensive than in those regenerated after storage in LN. Furthermore, the passage of cryopreserved embryos through another embryogenic stage led to further increase in variation. Interestingly, this detected variability appears to be in some measure reversible. The outcome of this study indicates that the cryopreservation induced phenotypic variability could be, at least partially, due to DNA methylation changes. Phenotypic variability observed in cryostored cocoa somatic-embryos is epigenetic in nature. This variability is partially reversible, not stochastic in nature but a directed response to the in-vitro culture and cryopreservation.

In-vitro neoformation of woody plants (apple, pear, Weigela)

International Nuclear Information System (INIS)

Chevreau, E.; Dufour, M.; Duron, M.

1990-01-01

Full text: Adventitious bud neoformation may induce variability in two ways: somaclonal variation, if the explant has undergone undifferentiated growth (callus); induced mutations, if a physical or chemical mutagen has been applied to the explant prior to the regeneration. Three apple scion cultivars ('Gala', 'Granny Smith', 'Golden Delicious') and four apple rootstock cultivars ('Mark', 'Novole', 'Lancep', 'Cepiland') were grown on basal apple multiplication medium. Leaves, internodes and roots were used for callogenesis and/or regeneration experiments. Scion varieties were more responsive than rootstocks. 1000 'Gala' neoformations will be planted in the field to investigate somaclonal variation. In pear, shoot regeneration was obtained from in-vitro leaves of 3 varieties of Pyrus communis ('Seckel', 'Louise Bonne', 'Comice') and one variety of Pyrus bretschneideri ('Crystal Pear'). It was observed that regeneration is still possible from leaves irradiated with up to 40 Gy of γ rays, or treated with 5mM ENU for one hour. In Weigela, stem segments (0.5 cm) from rooted in vitro plants of 5 cultivars were used in experiments to induce adventitious buds. On the cultivar 'Eva Rathke' the adventitious buds were detected as early as 10 to 15 days after the beginning of the culture. A mutagenic treatment was carried out by immersing explants of 'Bristol Ruby' in a suspension of ethyl methane sulfonate (EMS). Among 400 plants regenerated from treated explants, 5 mutants were detected after 5 years of field observation. Two of them seem to be solid mutants. Apparently in Weigela both homogeneous mutants and chimeras are produced by adventitious regeneration from mutagenised explants. (author)

Meristem micropropagation of cassava (Manihot esculenta) evokes genome-wide changes in DNA methylation.

Science.gov (United States)

Kitimu, Shedrack R; Taylor, Julian; March, Timothy J; Tairo, Fred; Wilkinson, Mike J; Rodríguez López, Carlos M

2015-01-01

There is great interest in the phenotypic, genetic and epigenetic changes associated with plant in vitro culture known as somaclonal variation. In vitro propagation systems that are based on the use of microcuttings or meristem cultures are considered analogous to clonal cuttings and so widely viewed to be largely free from such somaclonal effects. In this study, we surveyed for epigenetic changes during propagation by meristem culture and by field cuttings in five cassava (Manihot esculenta) cultivars. Principal Co-ordinate Analysis of profiles generated by methylation-sensitive amplified polymorphism revealed clear divergence between samples taken from field-grown cuttings and those recovered from meristem culture. There was also good separation between the tissues of field samples but this effect was less distinct among the meristem culture materials. Application of methylation-sensitive Genotype by sequencing identified 105 candidate epimarks that distinguish between field cutting and meristem culture samples. Cross referencing the sequences of these epimarks to the draft cassava genome revealed 102 sites associated with genes whose homologs have been implicated in a range of fundamental biological processes including cell differentiation, development, sugar metabolism, DNA methylation, stress response, photosynthesis, and transposon activation. We explore the relevance of these findings for the selection of micropropagation systems for use on this and other crops.

Mutation breeding in vivo and in vitro in vegetatively propagated crops

International Nuclear Information System (INIS)

Tulmann Neto, A.; Latado, R.R.; Tsai, S.M.; Derbyshire, M.T.; Yemma, A.F.; Scarpare Filho, J.A.; Ceravolo, L.; Rossi, A.C.; Namekata, T.; Pompeu, J. Jr.; Figueiredo, J.O.; Pio, R.; Tobias Domingues, E.; Santos, P.C.; Boliani, A.

2001-01-01

Mutation breeding in vivo and/or in vitro in vegetatively propagated crops as well as somaclonal variation can be used in Brazil in several crops to increase the genetic variability in characteristics of high importance. This was the objective of this research using ornamentals, citrus and bananas. Somaclonal variants can also be useful in these crops, based on the preliminary results observed in banana (Mycosphaerella musicola); where a short plant variant was selected in Brazil and the mutant resistant to yellow sigatoka, selected in Venezuela, showed resistance also in Brazil. Despite the increase in genetic variability in M 1 V 4 generation obtained after in vitro irradiation of meristems in banana, mutants resistant or tolerant to Fusarium were not selected, perhaps due to the limited number of plants evaluated. In citrus the first results from yield trials showed that following bud irradiation, it was possible to select plants of interest, e.g. mutants with a reduced number of seeds in the fruits. In ornamentals mutants induced by gamma rays in this project were released to the farmers. The results obtained in this research showed that biotechnology is a powerful tool that can be used in several ways in association with mutation breeding. (author)

In vitro technology for mutation breeding

International Nuclear Information System (INIS)

1986-10-01

The ultimate aim of the Co-ordinated Research Programme on In Vitro Technology for Mutation Breeding is to provide new effective tools for plant breeders to construct new cultivars, thus increasing agricultural production of food, feed and industrial raw material, particularly in developing countries. The participants of the research co-ordination meetings considered the potential of new advances of agricultural biotechnology, especially the use of in vitro techniques for mutation breeding. They discussed and co-ordinated plans in conjunction with the impact on plant breeding of novel technologies, such as use of somaclonal variation, cell hybridization and molecular genetics

Somaclonal variation of sugar beet resistant to pathogenic root rot Fusarium oxysporum var. orthoceras

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Urazaliev Kairat

2013-01-01

Full Text Available Sugar beet (Beta vulgaris L. - one of the most important crop in the world. In Kazakhstan, it is a traditional and major source of domestic sugar. The industry of cultivation and production of sugar beet is one of the priority areas of agricultural development of the country. In this paper, we studied the regeneration ability of different genotypes of sugar beet explants on selective media with the culture filtrate of the pathogen fungus F. oxysporum var. orthoceras. From the roots and shoots of sugar beet the pathogen Fusarium root rot was isolated. Was obtained pure cultures of the isolated pathogen. As a result, of morphological and cultural descriptions, as well as microbiological analysis it was revealed that the isolated pathogen is Fusarium Oxysporum. The results showed the pathogenicity of the fungus. For regeneration in vitro of the sugar beet genotypes resistant to the pathogen the culture media was optimized to the culture filtrate of the fungus F. oxysporum var. orthoceras. The frequency of shoot regeneration, depending on the genotype, was 1,0-12,5 %. On these explants the multiple shoot formations were observed.

Hezu 8, a new wheat variety developed with in vitro mutation technique

International Nuclear Information System (INIS)

Gao Mingwei

1992-01-01

A new wheat variety named Hezu 8 was developed by in vitro mutation techniques combining the somatic tissue culture with the radiation-induced mutation. This is the first one in the world for breeding wheat variety in such a way, that the nuclear technology was successfully applied to biotechnology. Hezu 8 is featured by high yield potential, early maturity, disease resistance, tolerance to moisture as well as good grain quality. In vitro mutation technique has proved to be helpful in increment of the frequency of somaclonal variation, promotion of the variation stability, acceleration of breeding process, reduction of the population size for variant selection, and finally, improvement of the breeding efficiency. In vitro mutation technique can be also widely applied to other crops and will open up a brilliant prospect for crop improvement

In vitro mutagenesis for the improvement of Josapine pineapple

International Nuclear Information System (INIS)

Rusli Ibrahim; Amir Hamzah

2006-01-01

Pineapple is the most important fruit in terms of revenue earner in Malaysia. There are about 10,000 ha cultivated with this fruit and half of this is owned by estates and planted for the canning industry. The export of canned pineapple is about 2 million standard cases annually valued at RM 60 million, while the export of fresh pineapple is about 40,000 tonnes worth about RM 10 million. The industry for canning is however, an ailing industry with production on the decline since the 70s. Somaclonal variations and induced mutation using irradiation in breeding are least invasive in changes to genetic make-up of an established variety and will be useful for improving the pineapple varieties. The use of tissue culture to generate somaclones with minute genetic changes that do not damage the overall varietal identity would be the most suitable tool to improve the variety. Protocols for the production of tissue culture plantlets of pineapple using bioreactor technology has been developed and proved to be much more efficient and productive compared to conventional method. In vitro mutagenesis using adventitious buds had produced new plants with smooth leaves, vigorous growth and ornamental-like characters. A total of 30,000 plants derived from tissue culture will be planted and screened in the field for the improvement of Josapine pineapple against bacterial heart rot disease and multiple crown. (Author)

Meristem micropropagation of cassava (Manihot esculenta evokes genome-wide changes in DNA methylation

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Shedrack Reuben Kitimu

2015-08-01

Full Text Available There is great interest in the phenotypic, genetic and epigenetic changes associated with plant in vitro culture known as somaclonal variation. In vitro propagation systems that are based on the use of microcuttings or meristem cultures are considered analogous to clonal cuttings and so widely viewed to be largely free from such somaclonal effects. In this study, we surveyed for epigenetic changes during propagation by meristem culture and by field cuttings in five cassava (Manihot esculenta cultivars. Principal Co-ordinate Analysis of profiles generated by Methylation Sensitive Amplified Polymorphism (MSAP revealed clear divergence between samples taken from field-grown cuttings and those recovered from meristem culture. There was also good separation between the tissues of field samples but this effect was less distinct among the meristem culture materials. Application of methylation-sensitive Genotype By Sequencing (msGBS identified 105 candidate epimarks that distinguish between field cutting and meristem culture samples. Cross referencing the sequences of these epimarks to the draft cassava genome revealed 102 sites associated with genes whose homologues have been implicated in a range of fundamental biological processes including cell differentiation, development, sugar metabolism, DNA methylation, stress response, photosynthesis, and transposon activation. We explore the relevance of these findings for the selection of micropropagation systems for use on this and other crops.

Increase of genetic variation in 'Blue Daisy' (Brachycome multifida) by in-vitro mutagenesis and polyploidization

International Nuclear Information System (INIS)

Walther, F.; Sauer, A.

1989-01-01

'Blue Daisy' was recently introduced from Australia and became a popular ornamental in Europe, but it lacks genetic variation and does not produce seeds under European environment conditions. Thus, the development of new cultivars is handicapped. 'Blue Daisy' is vegetatively propagated by cuttings. Techniques were developed to increase genetic variation by in-vitro mutation induction and polyploidization. For in-vitro propagation nodal segments with one pinnate leaf were placed on MS-medium containing 0.1 mg/l NAA and 2 mg/l BAP (medium 'a') or 2 mg/l IAA and 0.2 mg/l BAP (medium 'b') solidified by 0.6% Oxoid agar. 25 deg C and 16 h illumination (800 lux) resulted in highest propagation rates. After 4 weeks on medium 'b' large numbers of axillary shoots could be cut off and placed for rooting on 1/3 strength MS-medium supplemented with 2 mg/l IAA. Another 3 weeks later plantlets could be transferred into the greenhouse for further cultivation. The chromosome number of B. multifida is 2n=14. Polyploidy was obtained by placing in-vitro derived explants for about 3 weeks on solid MS-medium 'a' containing 0.1% colchicine. The resulting axillary buds were transferred for 3-5 months to medium 'b' for shoot development. After rooting and transfer into the greenhouse polyploidy was first determined by comparison of pollen grains from treated and untreated plants. For confirmation, the number of chromosomes was counted using the orcein-acetic squash method. Two different polyploid types were obtained: one more erect and one more hanging phenotype, both having enlarged leaves and flowers. X-ray doses of 10-50 Gy were applied to freshly cut nodal segments. The explants were placed on solid medium 'b' in petri dishes. Inhibition of shoot development was used as criterium of radiosensitivity. The described procedure of in-vitro propagation of Brachycome during 3 years did not give any somaclonal variant. The shoots developing after application of X-rays were rooted and all

Polymorphism and methylation patterns in Agave tequilana Weber var. 'Azul' plants propagated asexually by three different methods.

Science.gov (United States)

Díaz-Martínez, Miriam; Nava-Cedillo, Alejandro; Guzmán-López, José Alfredo; Escobar-Guzmán, Rocío; Simpson, June

2012-04-01

Genetic variation in three forms of asexually propagated Agave tequilana Weber var. 'Azul' plants namely offsets, bulbils and in vitro cultured individuals was studied by AFLP analysis. Low levels of variation were observed between mother plants and offsets and a higher level between mother plant and bulbils. Families obtained from commercial plantations showed lower levels of variation in comparison to families grown as ornamentals. No variation was observed between the original explant and four generations of in vitro cultured plants. Epigenetic variation was also studied by analyzing changes in methylation patterns between mother plants and offspring in each form of asexual reproduction. Offsets and bulbils showed an overall decrease in methylation whereas in vitro cultured plants showed patterns specific to each generation: Generations 1 and 4 showed overall demethylation whereas Generations 2 and 3 showed increased methylation. Analysis of ESTs associated with transposable elements revealed higher proportions of ESTs from Ty1-copia-like, Gypsy and CACTA transposable elements in cDNA libraries obtained from pluripotent tissue suggesting a possible correlation between methylation patterns, expression of transposable element associated genes and somaclonal variation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

The influence of micropropagation on growth and coppicing ability of Eucalyptus polybractea.

Science.gov (United States)

Goodger, Jason Q D; Woodrow, Ian E

2010-02-01

A micropropagation protocol was recently developed for Eucalyptus polybractea R.T. Baker, a commercially important eucalypt grown in short-rotation coppice cultivation and harvested for its foliar 1,8-cineole oil. Micropropagation of elite E. polybractea trees has resulted in selection gains for foliar oil traits, but decreased above-ground biomass accumulation has been observed in clones compared to related half-sibling families. This study aims to use a greenhouse study to investigate if micropropagation induces somaclonal variation that can account for the reduction in above-ground biomass in E. polybractea clones. Secondly, the study aims to compare the coppicing ability of micropropagated clones with related half-sibling seedlings using de-topped plantation-grown saplings. The results of the greenhouse study suggest that micropropagation of E. polybractea induces somaclonal variation that manifests in more mature leaf morphologies such as increased foliar oil concentrations and lower specific leaf area (SLA), attributable to an isobilateral arrangement of increased palisade mesophyll layers. Lower SLA, rather than differences in root allocation, is likely to be a key contributor to the lower relative growth rates observed in early sapling growth of micropropagated clones. In the field study, all micropropagated and seedling-derived E. polybractea saplings coppiced vigorously in the 12 months after de-topping. The coppice growth was so vigorous in the 12 months after de-topping that total above-ground biomass equalled that of the 27-month-old saplings, irrespective of propagation source. The morphological distinction between leaves of micropropagated and seed-derived plants was no longer evident in the coppice regrowth. The results presented here suggest that the micropropagated leaf morphology and the resultant growth reduction is transient and micropropagated plants coppice just as vigorously as seed-derived plants. Therefore, micropropagation is unlikely to

Micropropagation of Gerbera (Gerbera jamesonii Bolus).

Science.gov (United States)

Minerva, Ghani; Kumar, Surinder

2013-01-01

Gerbera (Gerbera jamesonii Bolus) is one of the most popular ornamental flowers worldwide and used both as cut flower and potted plant. Some of them show excellent agronomic characters such as color, floral diameter, stem length, and vigor, which make this plant of commercial importance. Conventionally, multiplication is done through seeds or rhizome cuttings. Rapid multiplication of elite cultivars of Gerbera, with improved agronomic traits, has been achieved by using both direct and indirect tissue culture methods. Direct shoot regeneration was accomplished from stem apices on MS medium supplemented with 1 mg/L 6-benzyladenine (BA) and 1 mg/L kinetin. Indirect shoot induction succeeded from callus differentiation has been achieved on MS medium containing 2 mg/L 2,4-dichlorophenoxyacetic acid, 0.5 mg/L indole-3-acetic acid, and 2 mg/L BA. The in vitro shoots, 4-5 cm long, were rooted by quick dipping the shoot bases for 3-5 s in 2,000 mg/L indole-3-butyric acid solution followed by transfer to the pots containing farmyard manure, soil, and sand (1:1:1 by volume). Initially, in vitro plantlets were covered with glass jars to maintain a high relative humidity (85-90%). As soon as new shoot growth begins, relative humidity is decreased by exposing them to the open environmental conditions prior transferring to the glasshouse. Indirect shoot regeneration increased the frequency of somaclonal variations. The selected somaclones were used in developing new and novel cultivars.

Genetic chimerism of Vitis vinifera cv. Chardonnay 96 is maintained through organogenesis but not somatic embryogenesis

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Butterlin Gisèle

2005-09-01

Full Text Available Abstract Background Grapevine can be a periclinal chimera plant which is composed at least of two distinct cell layers (L1, L2. When the cell layers of this plant are separated by passage through somatic embryogenesis, regenerated plants could show distinct DNA profiles and a novel phenotype which proved different from that of the parent plant. Results Genetically Chardonnay clone 96 is a periclinal chimera plant in which is L1 and L2 cell layers are distinct. Plants obtained via organogenesis through meristematic bulks are shown to be composed of both cell layers. However, plants regenerated through somatic embryogenesis starting from anthers or nodal explants are composed only of L1 cells. These somaclones do not show phenotypic differences to the parental clone up to three years after regeneration. Interestingly, the only somaclone showing an atypical phenotype (asymmetric leave shows a genotypic modification. Conclusion These results suggest that the phenotype of Chardonnay 96 does not result from an interaction between the two distinct cell layers L1 and L2. If phenotype conformity is further confirmed, somatic embryogenesis will result in true-to-type somaclones of Chardonnay 96 and would be well suitable for gene transfer.

In-vitro mutation breeding technology in maize

International Nuclear Information System (INIS)

Nesticky, M.

1988-08-01

Gamma-irradiation and in-vitro culture, separately or combined, as a tool for inducing mutation in maize were evaluated. This type of research has been hampered in maize because (i) maize is a cross pollinating crop and highly heterozygous and (ii) embryogenesis and plant regeneration of plants from in-vitro culture have been difficult. In the present study, carefully designed and elaborated experiments were conducted using an inbred line CH1 31 which is capable of somatic embryogenesis for the subject of mutagenesis and another line Bu 8Ro 2 for the test cross partner. Results showed: 1) Both the regeneration of plants from in-vitro culture and gamma-irradiation induced a similar spectrum of morphological variation. Although the variation with somaclones was more frequent that radiation induced mutations under the conditions used, combination of explant irradiation and in-vitro culture gave the highest frequencies of genetic variation. 2) Some of the mutations in quantitative characters can be recogned in heterozygous state. 3) Mutation can cause variation in combining ability (extent of heterosis). 4) Efficiency at embryogenesis differs with genotypes of maize. 3 refs, 11 figs, 4 tabs

SELEKSI IN VITRO UNTUK TOLERANSI TERHADAP KEKERINGAN PADA JAGUNG (Zea mays L. DENGAN POLYETHYLENE GLYCOL (PEG

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Kaswan Badami

2010-03-01

Full Text Available Genetic variation is a prerequisite for many breeding program that one of which can be generated through somaclon variation.  The objective of this research was to investigate effective media to induce embryo callii and to do in vitro callii regeneration for maize, and  in vitro selection was conducted by growing embryogenic callii on mediun containing polyethylene glycol (PEG.  Plant material used in this study was  5 madura cultivars i.e elos, tambin, guluk-guluk, talango and manding.   The results showed that (1 increasing addition 2,4-D on MS medium was significantly affected callii weight, however supplying 8 ppm 2,4-D was best for callii diameter, (2 The best medium to induce embryogenic callii formation was MS + 2 ppm 2,4-D + 3% manitol, (3 Increasing addition PEG  on MS medium can return the mays ES growth, and (4 A tambin and guluk-guluk cultivars was tolerance cultivars whereas manding cultivar was drought sensitive cultivar.

High-performance liquid chromatographic quantification of plumbagin from transformed rhizoclones of Plumbago zeylanica L.: inter-clonal variation in biomass growth and plumbagin production.

Science.gov (United States)

Nayak, Pranati; Sharma, Mukesh; Behera, Sailesh N; Thirunavoukkarasu, Manikkannan; Chand, Pradeep K

2015-02-01

An optimized protocol for induction and establishment of Agrobacterium rhizogenes-mediated hairy root cultures of Plumbago zeylanica L. was developed through selection of suitable explant type and the bacterial strain. The infection of internodal explants from an in vivo plant and leaves of in vitro origin with the A4 strain resulted in the emergence of hairy roots at a transformation frequency of 86.33 and 42.33 %, respectively. Independent transformed root somaclones (rhizoclones) capable of sustained growth were maintained under a low illumination in auxin-free agar-solidified Murashige and Skoog (MS) medium through subcultures at periodic intervals. The presence of pRi T L-DNA rolB or rolC genes and pRi T R-DNA mas2 gene in the transformed rhizoclone genome was ascertained by PCR amplification. Concentrations and type of carbon source, auxin and media strength were optimized for root biomass growth. Five independent rhizoclones each from A4- and LBA9402-transformed root lines were studied for their plumbagin accumulation at different growth phases, using HPLC analysis. The potential for plumbagin biosynthesis was expressed in all the tested rhizoclones, although distinct inter-clonal variations were noted. It was evident that maturation of hairy roots was more important for plumbagin accumulation; slow-growing and early-maturing rhizoclones accumulated more plumbagin compared to fast-growing and late-maturing rhizoclones. A4-induced rhizoclone HRA2B5 was identified as the most superior clone with a higher plumbagin yield potential in comparison with other tested hairy root clones, in vitro-grown non-transformed roots and in vivo roots of naturally occurring P. zeylanica.

CALLUS INDUCTION FROM 15 CARNATION (DIANTHUS CARYOPHYLLUS L. CULTIVARS

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Jaime A. TEIXEIRA DA SILVA

2014-12-01

Full Text Available Plant growth regulators (PGRs were used to induce callus in 15 carnation (Dianthus caryophyllus L.; Caryophyllaceae cultivars: Orange Sherbert, Avalanche, Magenta, La France, Stripe Red, Marie, Concerto PVP, Snap, Lucky Pierot, Cinnamon Tea, White Love, Siberia, Magesta, Spark Bruno, and Honono no Estejo. Seeds were initially sown on autoclaved moistened filter paper and internodes of surface-sterilized seedlings were used as explants. Most callus was induced in the presence of 0.5 mg/L α-naphthaleneacetic acid used together with 1 mg/L 6-benzyladenine or 1 mg/L 2,4-dichlorophenoxyacetic acid on basal Murashige and Skoog medium. Callus is not a desirable method to clonally propagate important germplasm but can serve as one possible way of deriving periclinal mutants as a result of somaclonal variation.

Crocus sativus L

African Journals Online (AJOL)

SAM

2014-06-25

709-712. Sivanesan I, Jana S, Jeong BR (2014). In-vitro shoot regeneration and microcorm development in Crocus vernus (L.) hill. Pak. J. Bot. 46(2):693-697. Sivanesan I, Jeong BR (2012). Identification of somaclonal variants in.

Somatic embryogenesis in plantain cultivar 'FHIA - 25' (AAB from meristem tips

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Dayana Rodríguez González

2015-07-01

Full Text Available Plantain cultivar 'FHIA – 25' (AAB shows high yielding qualities and high resistance to Black Sigatoka disease, but its sugar content in the fruit is low, so a regeneration method at cell level is necessary, such as somatic embryogenesis supported by biotechnological tools to improve fruit quality. This work was performed with the aim of establishing a plant regeneration method via somatic embryogenesis using initial explants of shoot apices from axillary buds in liquid culture medium. Homogenous embryogenic cell suspensions were obtained from mentioned explants. The highest cellular multiplication rates were achieved at 3,0% density. The incubation of somatic embryos during 30 days in the maturation culture medium permitted to increase germination. During the acclimatization stage, plants regenerated from somatic embryos, as well as plants from organogenesis, showed a high survival percentage (98 and 97 respectively, without somaclonal variation.

Somatic Embryogenesis: Still a Relevant Technique in Citrus Improvement.

Science.gov (United States)

Omar, Ahmad A; Dutt, Manjul; Gmitter, Frederick G; Grosser, Jude W

2016-01-01

The genus Citrus contains numerous fresh and processed fruit cultivars that are economically important worldwide. New cultivars are needed to battle industry threatening diseases and to create new marketing opportunities. Citrus improvement by conventional methods alone has many limitations that can be overcome by applications of emerging biotechnologies, generally requiring cell to plant regeneration. Many citrus genotypes are amenable to somatic embryogenesis, which became a key regeneration pathway in many experimental approaches to cultivar improvement. This chapter provides a brief history of plant somatic embryogenesis with focus on citrus, followed by a discussion of proven applications in biotechnology-facilitated citrus improvement techniques, such as somatic hybridization, somatic cybridization, genetic transformation, and the exploitation of somaclonal variation. Finally, two important new protocols that feature plant regeneration via somatic embryogenesis are provided: protoplast transformation and Agrobacterium-mediated transformation of embryogenic cell suspension cultures.

The induction of streptomycin resistance in tomato

International Nuclear Information System (INIS)

Jansen, D.E.; Snel, E.A.M.; Akerboom, M.; HiIle, J.

1990-01-01

Full text: The aim of the research is to investigate cytoplasmic genetics. For the analysis of organelle transfer and segregation in cybrids the presence of selectable and easily screenable genetic markers on organelles is indispensable. Streptomycin resistance is the best characterised cytoplasmic marker. The resistance is dominant and can be induced by a single basepair change in the chloroplast DNA. Protoplasts were treated with several MNU concentrations directly after isolation. Three months after the protoplast mutagenesis about 600 green colonies were isolated from 28x10 6 treated protoplasts. These colonies were retested several times on streptomycin containing media and approximately 150 colonies remained. We distinguished four classes of streptomycin resistance. Experiments were also done without the use of MNU. By somaclonal variation, only a small quantity of streptomycin resistant colonies was isolated at a 50 fold lower frequency. (author)

BIOTECHNOLOGY AND MOLECULAR-BASED METHODS FOR GENETIC IMPROVEMENT OF TULIPS

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Aurel Popescu

2012-04-01

Full Text Available Although the conventional methods of improvement have changed significantly throughout the last fifty years, additional tools and novel approaches are needed in order to fasten the process of creation new and highly valuable tulip varieties. The genetic base of tulip production can be preserved and widen by an integration of biotechnology tools in conventional breeding. Micropropagation in vitro may produce very fast large numbers of vigorous plants with high quality and free of endogenous pathogens. The in vitro rescue of embryos resulted from interspecific crosses between more or less distant species, chromosome doubling, somaclonal variation, transformation, and marker-aided selection and breeding are just a few of the examples of the applications of biotechnology in tulip improvement. This review provides an overview of the opportunities presented by the integration of plant biotechnology into the tulip improvement efforts.

Variational principles for locally variational forms

International Nuclear Information System (INIS)

Brajercik, J.; Krupka, D.

2005-01-01

We present the theory of higher order local variational principles in fibered manifolds, in which the fundamental global concept is a locally variational dynamical form. Any two Lepage forms, defining a local variational principle for this form, differ on intersection of their domains, by a variationally trivial form. In this sense, but in a different geometric setting, the local variational principles satisfy analogous properties as the variational functionals of the Chern-Simons type. The resulting theory of extremals and symmetries extends the first order theories of the Lagrange-Souriau form, presented by Grigore and Popp, and closed equivalents of the first order Euler-Lagrange forms of Hakova and Krupkova. Conceptually, our approach differs from Prieto, who uses the Poincare-Cartan forms, which do not have higher order global analogues

Tissue culture-induced genetic and epigenetic alterations in rice pure-lines, F1 hybrids and polyploids.

Science.gov (United States)

Wang, Xiaoran; Wu, Rui; Lin, Xiuyun; Bai, Yan; Song, Congdi; Yu, Xiaoming; Xu, Chunming; Zhao, Na; Dong, Yuzhu; Liu, Bao

2013-05-05

Genetic and epigenetic alterations can be invoked by plant tissue culture, which may result in heritable changes in phenotypes, a phenomenon collectively termed somaclonal variation. Although extensive studies have been conducted on the molecular nature and spectrum of tissue culture-induced genomic alterations, the issue of whether and to what extent distinct plant genotypes, e.g., pure-lines, hybrids and polyploids, may respond differentially to the tissue culture condition remains poorly understood. We investigated tissue culture-induced genetic and epigenetic alterations in a set of rice genotypes including two pure-lines (different subspecies), a pair of reciprocal F1 hybrids parented by the two pure-lines, and a pair of reciprocal tetraploids resulted from the hybrids. Using two molecular markers, amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP), both genetic and DNA methylation alterations were detected in calli and regenerants from all six genotypes, but genetic alteration is more prominent than epigenetic alteration. While significant genotypic difference was observed in frequencies of both types of alterations, only genetic alteration showed distinctive features among the three types of genomes, with one hybrid (N/9) being exceptionally labile. Surprisingly, difference in genetic alteration frequencies between the pair of reciprocal F1 hybrids is much greater than that between the two pure-line subspecies. Difference also exists in the pair of reciprocal tetraploids, but is to a less extent than that between the hybrids. The steady-state transcript abundance of genes involved in DNA repair and DNA methylation was significantly altered in both calli and regenerants, and some of which were correlated with the genetic and/or epigenetic alterations. Our results, based on molecular marker analysis of ca. 1,000 genomic loci, document that genetic alteration is the major cause of somaclonal variation in rice

The high frequency of variegated forms after in vitro mutagenesis in Saintpaulia ionantha Wendl.

Directory of Open Access Journals (Sweden)

Marek Gaj

2014-01-01

Full Text Available The leaf-explants of Saintpaulia ionantha Wendl. var.'miniature' were treated by different doses of MNH and cultured on shoot regeneration medium. A strong toxic effect of some MNH doses on explant survival during the first two subcultures was noticed. The explants surviving treatment regenerated shoots with the efficiency comparable to the control. The high number of shoots regenerated from mutagenised leaves showed chlorophyll chimerism (so-called variegated forms. The use of 5 mM MNH for 1.5 or 2 h was found very effective, as 100% of survived explants regenerated variegated shoots. Besides hundreds of variegated forms also leaf-shape and flower-colour variants were observed in MNH-treated culture. Somaclonal variation was not observed in the control culture. The results indicate the great efficiency of in vitro applied MNH for in-duction of morphological variants of Saintpaulia, and especially variegated forms.

In vitro techniques for crop improvement

International Nuclear Information System (INIS)

1985-01-01

The film refers to principles of plant tissue culture - laboratory requirements, media preparation, explant establishment and subculturing method. In vitro growth and development of crop plants are demonstrate and the application of in vitro techniques in plant breeding is discussed. The second part of the film shows the application of cell, tissue and organ culture in plants. Micropropagation and virus eradication are important technologies for the improvement of vegetatively propagated plants; zygotic embryo rescue techniques are used for distant hybridization, especially in cereals. Plant biotechnology offers a potent means for the in vitro generation of enhanced genetic variability - somaclonal and mutagen induced variation. Principles of the isolation and culture of plant protoplasts are explained and their potential for somatic hybridization in higher plants is demonstrated. Haploids are valuable to accelerate breeding cycles of plants. Plant biotechnology is described as an important complementary tool to conventional plant breeding methods

Estimation of genetic diversity in rice ( Oryza sativa L. ) genotypes ...

African Journals Online (AJOL)

Thirty rice genotypes comprising land races, pure lines, somaclones, breeding lines and varieties specifically adapted to costal saline environments were characterized by SSR markers and morphological characters in this study. Out of 35 primers of SSR markers, 28 were found to be polymorphic. The PIC value ranged ...

Food Fingerprinting: Characterization of the Ecuadorean Type CCN-51 of Theobroma cacao L. Using Microsatellite Markers.

Science.gov (United States)

Herrmann, Luise; Felbinger, Christine; Haase, Ilka; Rudolph, Barbara; Biermann, Bernhard; Fischer, Markus

2015-05-13

The cocoa type "Colección Castro Naranjal 51" (CCN-51) is known for its resistance to specific climate conditions and its high yield, but it shows a weaker flavor profile and therefore is marketed as bulk cocoa. In a previous study, the two cocoa types Arriba and CCN-51 could easily be distinguished, but differences among the CCN-51 samples were observed. This was unexpected, as CCN-51 is reported to be a clone. To confirm whether CCN-51 is a pure clone, 10 simple sequence repeats (SSR) located on the nuclear genome were used to analyze various CCN-51 samples in comparison to the cocoa varieties Arriba and Criollo. As expected, there are differences in the SSR pattern among CCN-51, Arriba, and Criollo, but a variability within the CCN-51 sample set was detected as well. The previously described sequence variation in the chloroplast genome was confirmed by a variability in the microsatellite loci of the nuclear genome for a comprehensive cultivar collection of CCN-51 of both bean and leaf samples. In summary, beneath somaclonal variation, misidentification of plant collections and also sexual reproduction of CCN-51 can be suggested.

Dynamics of nonholonomic systems from variational principles embedded variation identity

International Nuclear Information System (INIS)

Guo Yongxin; Liu Shixing; Liu Chang; Chang Peng

2009-01-01

Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

Dynamics of nonholonomic systems from variational principles embedded variation identity

Energy Technology Data Exchange (ETDEWEB)

Guo Yongxin, E-mail: yxguo@lnu.edu.c [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Shixing [College of Physics, Liaoning University, Shenyang 110036 (China); Liu Chang; Chang Peng [Department of Applied Mechanics, Beijing Institute of Technology, Beijing 100081 (China)

2009-10-19

Nondeterminacy of dynamics, i.e., the nonholonomic or the vakonomic, fundamental variational principles, e.g., the Lagrange-d'Alembert or Hamiltonian, and variational operators, etc., of nonholonomic mechanical systems can be attributed to the non-uniqueness of ways how to realize nonholonomic constraints. Making use of a variation identity of nonholonomic constraints embedded into the Hamilton's principle with the method of Lagrange undetermined multipliers, three kinds of dynamics for the nonholonomic systems including the vakonomic and nonholonomic ones and a new one are obtained if the variation is respectively reduced to three conditional variations: vakonomic variation, Hoelder's variation and Suslov's variation, defined by the identity. Therefore, different dynamics of nonholonomic systems can be derived from an integral variational principle, utilizing one way of embedding constraints into the principle, with different variations. It is verified that the similar embedding of the identity into the Lagrange-d'Alembert principle gives rise to the nonholonomic dynamics but fails to give the vakonomic one unless the constraints are integrable.

Genetic variability of woolly aphid (Adelges laricis Vall.) resistance in European larch (Larix decidua Mill.)

Energy Technology Data Exchange (ETDEWEB)

Blada, I. [Forest Research Inst., Bucharest (Romania)

1995-12-31

One hundred and eleven clones of European larch were exposed to the woolly aphid and then outplanted in three locations using a randomized complete block design. At ages 11 and 19 years resistance was measured on 102 clones at 2 locations. Highly significant genetic differences were observed among the clones at both locations and at both ages. Highly significant clone x location, clone x location x age interactions were also observed. Differences between the most resistant and most susceptible clones was 483%. Sufficient genetic variation for a breeding program was present. Broad-sense heritability estimates for Adelges resistance varied by location. Significant age to age, location to location and age to location phenotypic correlation for resistance were found. Larch resistance seems to be under polygenic control. A substantial genetic gain could be achieved by selecting the best clones and using vegetative propagation, including somaclonal embryogenesis, for multiplication. 23 refs, 2 figs, 8 tabs

Micropropagation and Biomass Production of True-to-Type Stevia rebaudiana Bertoni.

Science.gov (United States)

Modi, Arpan R; Sharma, Vikas; Patil, Ghanshyam; Singh, Amritpal S; Subhash, N; Kumar, Nitish

2016-01-01

Here we describe an efficient micropropagation protocol for Stevia rebaudiana Bertoni. We present experiments carried out to optimize the suitable media for in vitro shoot multiplication and root induction and to study the effect of culture vessel on shoot multiplication. Among all different media tested for in vitro shoot multiplication, hormone-free liquid medium is most suitable. The highest number of nodes per shoot (5.4) and length of shoot (4.76 cm) at 4 weeks after subculturing are observed when single node explants are placed on modified MS medium supplemented with 1 % sucrose and 0.7 % agar. The highest response of multiplication rate (9.56) is observed on half strength of macroelement of MS with full strength of microelement of MS and 170 mg/l KH2PO4, and 185 mg/l MgSO4 in plastic growth container. Further, RAPD marker analysis of in vitro-raised plants maintained their clonal fidelity and true-to-type without showing any somaclonal variation.

EFFECTIVENESS OF SELECTION OF WHEAT TO MODERN REQUIREMENTS FOR SUSTAINABLE DEVELOPMENT OF AGRICULTURE III. ENERGY PRODUCTIVITY OF CROPS

Directory of Open Access Journals (Sweden)

Elisaveta Vasileva

2014-03-01

Full Text Available Aim of the study was to conclude on adaptation of modern varieties to the requirements of sustainable agriculture and hence the effectiveness of their methods of selection with respect to these requirements. The comparison between genotypes in two directions - by the selection methods by which they were established and according to the time of their creation. Energy assessment shows that the gross energy yield of grain is higher ( in average 5% over standard for varieties produced by the methods of the Intervarietal hybridization and during the period 1995 to 1999. While absolute maximum values of the energy productivity of grain (at N18 and maximum average total gross energy productivity of crops (4% above standard were detected in genotypes generated by the methods of mutagenesis by irradiation with gamma rays. Absolute maximum value of the energy productivity of crops were reported in cultivar Zdravko (at N18, which was established by the method of plant biotechnology by combining and somaclonal variation.

Genetic variability of woolly aphid (Adelges laricis Vall.) resistance in European larch (Larix decidua Mill.)

Energy Technology Data Exchange (ETDEWEB)

Blada, I [Forest Research Inst., Bucharest (Romania)

1996-12-31

One hundred and eleven clones of European larch were exposed to the woolly aphid and then outplanted in three locations using a randomized complete block design. At ages 11 and 19 years resistance was measured on 102 clones at 2 locations. Highly significant genetic differences were observed among the clones at both locations and at both ages. Highly significant clone x location, clone x location x age interactions were also observed. Differences between the most resistant and most susceptible clones was 483%. Sufficient genetic variation for a breeding program was present. Broad-sense heritability estimates for Adelges resistance varied by location. Significant age to age, location to location and age to location phenotypic correlation for resistance were found. Larch resistance seems to be under polygenic control. A substantial genetic gain could be achieved by selecting the best clones and using vegetative propagation, including somaclonal embryogenesis, for multiplication. 23 refs, 2 figs, 8 tabs

Evaluation of genetic variability in micropropagated propagules of ornamental pineapple [Ananas comosus var. bracteatus (Lindley) Coppens and Leal] using RAPD markers.

Science.gov (United States)

Santos, M D M; Buso, G C S; Torres, A C

2008-10-21

The objective of the present study was to evaluate the genetic variability in micropropagated plantlets of ornamental pineapple, after the fourth period of subculture. The basal culture medium consisted of MS salts, vitamins, 3% sucrose, liquid formulation, supplemented with 6-benzylaminopurine (BAP) at concentrations of 0.125, 0.25, 0.5, 1.0, and 2.0 mg/L. The addition of BAP influenced the occurrence of genetic variation revealed using random amplified polymorphic DNA (RAPD) markers. Of a total of 520 primers tested, 44 were selected and amplified; 402 monomorphic bands (97.2%) and 18 polymorphic bands (2.8%) resulted among regenerated plantlets. The polymorphic fragments were produced by 12 primers (OPA-01, OPA-20, OPB-01, OPB-19, OPC-19, OPF-13, OPL-17, OPM-13, OPP-16, OPT-07, OPV-19, and OPX-03). Among the primers that identified polymorphism, OPA-01, OPA-20, OPB-19, OPC-19, OPL-17, OPP-16, and OPX-3 each showed, one polymorphic band and OPF-13 amplified a maximum of three bands. In this study, the RAPD technique was effective in showing the occurrence of somaclonal variations that occur during the micropropagation process of ornamental pineapple cultivation in BAP-supplemented medium, and it is possible to detect the presence of genetic variation in early stages of plant development.

Calculus of variations

CERN Document Server

Elsgolc, L E; Stark, M

1961-01-01

Calculus of Variations aims to provide an understanding of the basic notions and standard methods of the calculus of variations, including the direct methods of solution of the variational problems. The wide variety of applications of variational methods to different fields of mechanics and technology has made it essential for engineers to learn the fundamentals of the calculus of variations. The book begins with a discussion of the method of variation in problems with fixed boundaries. Subsequent chapters cover variational problems with movable boundaries and some other problems; sufficiency

Evaluation of sugarcane ( Saccharum officinarum L.) somaclonal ...

African Journals Online (AJOL)

A total of four plants which regenerated from the tolerant calli were selected but the best in vigor were grown in in vitro and hydroponic systems under salinity stress (with the previous levels) as compared to source variety. With increasing supply of NaCl in both systems, root growth was more adversely affected than shoot ...

Variational and quasi-variational inequalities in mechanics

CERN Document Server

Kravchuk, Alexander S

2007-01-01

The essential aim of the present book is to consider a wide set of problems arising in the mathematical modelling of mechanical systems under unilateral constraints. In these investigations elastic and non-elastic deformations, friction and adhesion phenomena are taken into account. All the necessary mathematical tools are given: local boundary value problem formulations, construction of variational equations and inequalities, and the transition to minimization problems, existence and uniqueness theorems, and variational transformations (Friedrichs and Young-Fenchel-Moreau) to dual and saddle-point search problems. Important new results concern contact problems with friction. The Coulomb friction law and some others are considered, in which relative sliding velocities appear. The corresponding quasi-variational inequality is constructed, as well as the appropriate iterative method for its solution. Outlines of the variational approach to non-stationary and dissipative systems and to the construction of the go...

Calculus of variations

CERN Document Server

Elsgolc, Lev D

2007-01-01

This concise text offers both professionals and students an introduction to the fundamentals and standard methods of the calculus of variations. In addition to surveys of problems with fixed and movable boundaries, it explores highly practical direct methods for the solution of variational problems.Topics include the method of variation in problems with fixed boundaries; variational problems with movable boundaries and other problems; sufficiency conditions for an extremum; variational problems of constrained extrema; and direct methods of solving variational problems. Each chapter features nu

Somatic embryogenesis on Musa AAAB, cv. FHIA-18, using liquids culture mediums

Directory of Open Access Journals (Sweden)

Luis A. Barranco

2002-04-01

Full Text Available Homogenous cell suspensions were iniciated from somatic embryos in the globular stage and the greatest volume of cell biomass on multiplying the suspensions at a density of 3.0% PCV. From the fifteenth day in culture medium for the formation of embryos, structures consisting of proembryos and somatic embryos in the globular stage started to form. With respect to the densities studied, the best results were obtained with 100 mgFW, where 1 871 SE.l-1 formed with a weight of 248 mgFW.l-1 after 30 days. With an initial density of 0.6 gFW in the culture medium for secondary multiplication, an increase of 42.9-fold the initial amount of fresh weight was obtained; after 60 days of culture 15 985 SE.l-1 were obtained. The greatest percentage of maturation was obtained with 400 mgFW with 70% of mature somatic embryos. The positive effect of Biobras-6 (brassinosteroid analogous was confirmed, with a concentration of 0.01 mg.l-1 the best germination percentages were obtained in liquid and semisolid culture medium. Embryo germination in temporaly inmersion (RITA was achieved with an inoculum density of 0.5 gFW for system with 85% germination. One thousand plants obtained from somatic embryos were taken to ex vitro environment, along with plants derived from conventional micropropagation (shoot tips to carry out studies on the possible presence of somaclonal variation. During the first cycle of production, the plants derived from the two methods in vitro culture showed differences with respect to the plants derived from corms in height, diameter and number of suckers. In the second production cycle, the plants from somatic embryos showed similar characteristics to the plants derived from shoot tip and corms with respect to the morphological parameters evaluated, with only 0.2% of the plants with phenotypic changes. Key Words: Banana, cellular density, germination, somaclonal variability, somatic embryo

Optimization of Protocols for In Vitro Regeneration of Sugarcane (Saccharum officinarum

Directory of Open Access Journals (Sweden)

Shakra Jamil

2017-01-01

Full Text Available Sugarcane contributes 60–70% of annual sugar production in the world. Somaclonal variation has potential to enhance genetic variation present within a species. Present study was done to optimize an in vitro propagation protocol for sugarcane. The experiments included four varieties, 9 callus induction media, 27 regeneration media, and 9 root induction media under two-factor factorial CRD. Data were recorded on callus induction, embryogenic callus formation, shoot elongation (cm, root induction, and plant regeneration. Statistically significant differences existed between genotypes and treatments for callus induction (%, embryogenic callus formation (%, shoot elongation (cm, root induction, and plant regeneration (%. All parameters showed dependency on genotypes, culture media, and their interaction. Highest callus induction (95% embryogenic callus formation (95% was observed in callus induction media 5. Highest plantlet regeneration (98.9% capacity was observed in regeneration media 11 whereas maximum shoot elongation (12.13 cm and root induction (8.32 were observed in rooting media 4. G1 showed best response for all traits and vice versa for G4. Hence it was concluded that G1, callus induction media 5, regeneration media 11, and rooting media 4 are the best conditions for in vitro propagation of sugarcane.

Is there much variation in variation? Revisiting statistics of small area variation in health services research

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Ibáñez Berta

2009-04-01

Full Text Available Abstract Background The importance of Small Area Variation Analysis for policy-making contrasts with the scarcity of work on the validity of the statistics used in these studies. Our study aims at 1 determining whether variation in utilization rates between health areas is higher than would be expected by chance, 2 estimating the statistical power of the variation statistics; and 3 evaluating the ability of different statistics to compare the variability among different procedures regardless of their rates. Methods Parametric bootstrap techniques were used to derive the empirical distribution for each statistic under the hypothesis of homogeneity across areas. Non-parametric procedures were used to analyze the empirical distribution for the observed statistics and compare the results in six situations (low/medium/high utilization rates and low/high variability. A small scale simulation study was conducted to assess the capacity of each statistic to discriminate between different scenarios with different degrees of variation. Results Bootstrap techniques proved to be good at quantifying the difference between the null hypothesis and the variation observed in each situation, and to construct reliable tests and confidence intervals for each of the variation statistics analyzed. Although the good performance of Systematic Component of Variation (SCV, Empirical Bayes (EB statistic shows better behaviour under the null hypothesis, it is able to detect variability if present, it is not influenced by the procedure rate and it is best able to discriminate between different degrees of heterogeneity. Conclusion The EB statistics seems to be a good alternative to more conventional statistics used in small-area variation analysis in health service research because of its robustness.

THE PARTICULARITIES OF PROLONGED CULTIVATION OF PLANTS-REGENERANTS OF TOMATO INTERSPECIFIC HYBRIDS

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T. N. Miroshnichenko

2015-01-01

Full Text Available The particularities of the changes of the morphological parameters of plants-regenerants of tomato hybrids F1 during prolonged cultivation in conditions of in vitro have been studied. The cultivation during 12 passages in hormoneless MS medium does not lead to somaclonal variants, but act to raise the increasing of coefficient of variability of plants-regenerants features. 

Quantum Variational Calculus

OpenAIRE

Malinowska , Agnieszka B.; Torres , Delfim

2014-01-01

International audience; Introduces readers to the treatment of the calculus of variations with q-differences and Hahn difference operators Provides the reader with the first extended treatment of quantum variational calculus Shows how the techniques described can be applied to economic models as well as other mathematical systems This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of it...

Genetics and variation

Science.gov (United States)

John R. Jones; Norbert V. DeByle

1985-01-01

The broad genotypic variability in quaking aspen (Populus tremuloides Michx.), that results in equally broad phenotypic variability among clones is important to the ecology and management of this species. This chapter considers principles of aspen genetics and variation, variation in aspen over its range, and local variation among clones. For a more...

Somaclonal variation and irradiation in sugarcane calli for selection against red rot, water-logged conditions and delayed or non-flowering characters

International Nuclear Information System (INIS)

Samad, M.A.; Begum, S.; Majid, M.A.

2001-01-01

A protocol for callus induction and plant regeneration from primordial leaf culture was established in sugarcane cv. 'Isd-16'. The regenerated (R 1 ) plants were grown in field, and the subsequent propagations (R 2 -R 4 ) were screened for resistance to red rot disease and waterlogged conditions. Three clones showed moderate resistance (MR) to red rot and 3 clones were tolerant to water-logging in R 4 . In another experiment, callus cultures were irradiated with 2 to 10 Gy gamma rays. The maximum regeneration was obtained from 3 Gy treatment. Of the 768 R 1 plants, 50 survived to maturity. R 2 and R 3 populations were selected for delayed or non-flowering types. Five R 3 canes showed delayed flowering. (author)

Some remarks on variational and quasi-variational inequalities of monotone operators

International Nuclear Information System (INIS)

Siddiqi, A.H.

1990-08-01

In this paper we study a fairly general class of variational and quasi-variational inequalities problem which represent some important physical phenomena. Several well-known results concerning variational inequalities are special cases of our results. Existence, uniqueness and numerical analysis of this problem have been studied. (author). 39 refs

Ensembl variation resources

Directory of Open Access Journals (Sweden)

Marin-Garcia Pablo

2010-05-01

Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.

Short rotation Wood Crops Program

Energy Technology Data Exchange (ETDEWEB)

Wright, L.L.; Ehrenshaft, A.R.

1990-08-01

This report synthesizes the technical progress of research projects in the Short Rotation Woody Crops Program for the year ending September 30, 1989. The primary goal of this research program, sponsored by the US Department of Energy's Biofuels and Municipal Waste Technology Division, is the development of a viable technology for producing renewable feedstocks for conversion to biofuels. One of the more significant accomplishments was the documentation that short-rotation woody crops total delivered costs could be $40/Mg or less under optimistic but attainable conditions. By taking advantage of federal subsidies such as those offered under the Conservation Reserve Program, wood energy feedstock costs could be lower. Genetic improvement studies are broadening species performance within geographic regions and under less-than-optimum site conditions. Advances in physiological research are identifying key characteristics of species productivity and response to nutrient applications. Recent developments utilizing biotechnology have achieved success in cell and tissue culture, somaclonal variation, and gene-insertion studies. Productivity gains have been realized with advanced cultural studies of spacing, coppice, and mixed-species trials. 8 figs., 20 tabs.

Gene pool conservation and tree improvement in Serbia

Directory of Open Access Journals (Sweden)

Isajev Vasilije

2009-01-01

Full Text Available This paper presents the concepts applied in the gene pool conservation and tree improvement in Serbia. Gene pool conservation of tree species in Serbia includes a series of activities aiming at the sustainability and protection of genetic and species variability. This implies the investigation of genetic resources and their identification through the research of the genetic structure and the breeding system of individual species. Paper also includes the study of intra- and inter-population variability in experiments - provenance tests, progeny tests, half- and full-sib lines, etc. The increased use of the genetic potential in tree improvement in Serbia should be intensified by the following activities: improvement of production of normal forest seed, application of the concept of new selections directed primarily to the improvement of only one character, because in that case the result would be certain, establishment and management of seed orchards as specialized plantations for long-term production of genetically good-quality forest seeds, and the shortening of the improvement process by introducing new techniques and methods (molecular markers, somaclonal variation, genetic engineering, protoplast fusion, micropropagation, etc..

In vitro regeneration of Amazonian pineapple (Ananas comosus plants ecotype Gobernadora

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Héctor Alexander Blanco Flores

2017-01-01

Full Text Available There are a number of pineapple (Ananas comosus cultivars and ecotypes of local commercial importance in Venezuela, among them the Amazonian ones, cultivated mainly by the aboriginal Piaroa, are of relevance. They sow the propagules, which restricts the availability of material for large-scale cultivation. This limitation was approached by plant tissue culture for in vitro propagation of Amazonian pineapple plants, Gobernadora ecotype, through somatic embryogenesis (ES and adventitious organogenesis (OA. Basal and intermediate sections of leaves were tested. Only the leaf base sections (FBS were morphogenically induced. The highest number of vitroplants (1.58 plants / explant was obtained from the embryogenic callus induced in MS medium with Picloram 10 mg.L-1 + Thidiazuron 2 mg.L-1, transferred to MS medium without hormones. In the organogenic process, the highest number of plants/explants (5 was obtained directly in MS with naphthaleneacetic acid 5 mg.L-1 + benzylaminopurine 0.25 mg.L-1, transferred to MS. The latter being the best in vitro culture system due to its productivity and for being a method that minimizes somaclonal variation.

Uv - b irradiation effects on biological activities and cytological behavior of sainfoin (onobrychis viciifolia scop.) grown in vivo and in vitro

International Nuclear Information System (INIS)

Mohajer, S.; Taha, R. M.; Mohajer, M.; Javan, I. Y.

2015-01-01

To investigate the feasibility of UV-B irradiation (312 nm), seeds of Onobrychis viciifolia were exposed to five different intensities for determining the effectiveness of cellular behavior, nutritional constituents and biological activities in In vivo and In vitro growth cultures. The atomic spectroscopy analysis confirmed that concentrations of two macronutrients (P and N) improved after UV-B exposure as compared with control plants. Near infrared radiation conducted on both In vivo and In vitro plants showed significant differences on dry matter digestibility (DMD) and crude fiber (CF). Flavonoid and phenolic compounds were increased in both growth cultures by 40 percentage intensity of UV-B irradiation, although In vitro plants had the higher compounds than intact plants. Increasing the UV-B irradiation intensity was also found to yield positive effect on anthocyanin. Observations on cellular behavior such as determination of nuclear and cell areas, mitotic index and chromosomal aberrations were proven to be essential in deducing the effectiveness of UV-B irradiation to induce somaclonal variation in sainfoin. (author)

Variation and Mathematics Pedagogy

Science.gov (United States)

Leung, Allen

2012-01-01

This discussion paper put forwards variation as a theme to structure mathematical experience and mathematics pedagogy. Patterns of variation from Marton's Theory of Variation are understood and developed as types of variation interaction that enhance mathematical understanding. An idea of a discernment unit comprising mutually supporting variation…

Microsatellite loci and peroxidase alleles correlation in somaclonal ...

African Journals Online (AJOL)

STORAGESEVER

2010-07-19

Jul 19, 2010 ... 1Department of Plant Breeding, Faculty of Agriculture and Natural Resources, Islamic Azad University, Karaj Branch, ... Due to open pollination of this species, ... callus initiation and embryonic calli in lettuce (Xiaoli et al.,.

Intrapopulation genome size variation in D. melanogaster reflects life history variation and plasticity.

Directory of Open Access Journals (Sweden)

Lisa L Ellis

2014-07-01

Full Text Available We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions.

Intrapopulation Genome Size Variation in D. melanogaster Reflects Life History Variation and Plasticity

Science.gov (United States)

Ellis, Lisa L.; Huang, Wen; Quinn, Andrew M.; Ahuja, Astha; Alfrejd, Ben; Gomez, Francisco E.; Hjelmen, Carl E.; Moore, Kristi L.; Mackay, Trudy F. C.; Johnston, J. Spencer; Tarone, Aaron M.

2014-01-01

We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions. PMID:25057905

The contribution of additive genetic variation to personality variation: heritability of personality.

Science.gov (United States)

Dochtermann, Ned A; Schwab, Tori; Sih, Andrew

2015-01-07

Individual animals frequently exhibit repeatable differences from other members of their population, differences now commonly referred to as 'animal personality'. Personality differences can arise, for example, from differences in permanent environmental effects--including parental and epigenetic contributors--and the effect of additive genetic variation. Although several studies have evaluated the heritability of behaviour, less is known about general patterns of heritability and additive genetic variation in animal personality. As overall variation in behaviour includes both the among-individual differences that reflect different personalities and temporary environmental effects, it is possible for personality to be largely genetically influenced even when heritability of behaviour per se is quite low. The relative contribution of additive genetic variation to personality variation can be estimated whenever both repeatability and heritability are estimated for the same data. Using published estimates to address this issue, we found that approximately 52% of animal personality variation was attributable to additive genetic variation. Thus, while the heritability of behaviour is often moderate or low, the heritability of personality is much higher. Our results therefore (i) demonstrate that genetic differences are likely to be a major contributor to variation in animal personality and (ii) support the phenotypic gambit: that evolutionary inferences drawn from repeatability estimates may often be justified. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Gerbera micropropagation.

Science.gov (United States)

Cardoso, Jean C; Teixeira da Silva, Jaime A

2013-12-01

Gerbera jamesonii (gerbera) is an important cut-flower in the global floricultural industry. Micropropagation is the main system used to clonally propagate gerbera in vitro resulting in the production of millions of plantlets each year. Numerous types of explants and protocols for micropropagation have been established and used for gerbera. Shoot tips are the commonly used explant while adventitious shoot induction from the capitulum is also a popular method. Most papers in the literature have focused on testing the influence of different types and combinations of plant growth regulators with the aim of improving the regeneration and multiplication stage of one or few cultivars. Genotype is one of the most influential factors on the response of gerbera in vitro. Despite this, no successful universal protocol has yet been developed for multiple cultivars, limiting the usefulness of current protocols for commercial biotechnology labs. Slow-growing endogenous bacteria are one of the most important problems in gerbera micropropagation but require more studies on control and prevention. Individual shoots are normally easy to root, usually in excess of 90% of plantlets, but the acclimatization stage requires improvements and new technologies to increase the survival of plants. Epigenetic variations in micropropagated gerbera are frequently observed only with high concentrations of cytokinins in the culture medium but somaclonal variation is rare. Copyright © 2013 Elsevier Inc. All rights reserved.

Variational submanifolds of Euclidean spaces

Science.gov (United States)

Krupka, D.; Urban, Z.; Volná, J.

2018-03-01

Systems of ordinary differential equations (or dynamical forms in Lagrangian mechanics), induced by embeddings of smooth fibered manifolds over one-dimensional basis, are considered in the class of variational equations. For a given non-variational system, conditions assuring variationality (the Helmholtz conditions) of the induced system with respect to a submanifold of a Euclidean space are studied, and the problem of existence of these "variational submanifolds" is formulated in general and solved for second-order systems. The variational sequence theory on sheaves of differential forms is employed as a main tool for the analysis of local and global aspects (variationality and variational triviality). The theory is illustrated by examples of holonomic constraints (submanifolds of a configuration Euclidean space) which are variational submanifolds in geometry and mechanics.

Bilateral renal artery variation

OpenAIRE

Üçerler, Hülya; Üzüm, Yusuf; İkiz, Z. Aslı Aktan

2014-01-01

Each kidney is supplied by a single renal artery, although renal artery variations are common. Variations of the renal arteryhave become important with the increasing number of renal transplantations. Numerous studies describe variations in renalartery anatomy. Especially the left renal artery is among the most critical arterial variations, because it is the referred side forresecting the donor kidney. During routine dissection in a formalin fixed male cadaver, we have found a bilateral renal...

Studying Variation in Tunes

NARCIS (Netherlands)

Janssen, B.; van Kranenburg, P.

2014-01-01

Variation in music can be caused by different phenomena: conscious, creative manipulation of musical ideas; but also unconscious variation during music recall. It is the latter phenomenon that we wish to study: variation which occurs in oral transmission, in which a melody is taught without the help

Anatomic variation and orgasm: Could variations in anatomy explain differences in orgasmic success?

Science.gov (United States)

Emhardt, E; Siegel, J; Hoffman, L

2016-07-01

Though the public consciousness is typically focused on factors such as psychology, penis size, and the presence of the "G-spot," there are other anatomical and neuro-anatomic differences that could play an equal, or more important, role in the frequency and intensity of orgasms. Discovering these variations could direct further medical or procedural management to improve sexual satisfaction. The aim of this study is to review the available literature of anatomical sexual variation and to explain why this variation may predispose some patients toward a particular sexual experience. In this review, we explored the available literature on sexual anatomy and neuro-anatomy. We used PubMed and OVID Medline for search terms, including orgasm, penile size variation, clitoral variation, Grafenberg spot, and benefits of orgasm. First we review the basic anatomy and innervation of the reproductive organs. Then we describe several anatomical variations that likely play a superior role to popular known variation (penis size, presence of g-spot, etc). For males, the delicate play between the parasympathetic and sympathetic nervous systems is vital to achieve orgasm. For females, the autonomic component is more complex. The clitoris is the primary anatomical feature for female orgasm, including its migration toward the anterior vaginal wall. In conclusions, orgasms are complex phenomena involving psychological, physiological, and anatomic variation. While these variations predispose people to certain sexual function, future research should explore how to surgically or medically alter these. Clin. Anat. 29:665-672, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Introduction to global variational geometry

CERN Document Server

Krupka, Demeter

2015-01-01

The book is devoted to recent research in the global variational theory on smooth manifolds. Its main objective is an extension of the classical variational calculus on Euclidean spaces to (topologically nontrivial) finite-dimensional smooth manifolds; to this purpose the methods of global analysis of differential forms are used. Emphasis is placed on the foundations of the theory of variational functionals on fibered manifolds - relevant geometric structures for variational principles in geometry, physical field theory and higher-order fibered mechanics. The book chapters include: - foundations of jet bundles and analysis of differential forms and vector fields on jet bundles, - the theory of higher-order integral variational functionals for sections of a fibred space, the (global) first variational formula in infinitesimal and integral forms- extremal conditions and the discussion of Noether symmetries and generalizations,- the inverse problems of the calculus of variations of Helmholtz type- variational se...

Genome Variation Map: a data repository of genome variations in BIG Data Center

OpenAIRE

Song, Shuhui; Tian, Dongmei; Li, Cuiping; Tang, Bixia; Dong, Lili; Xiao, Jingfa; Bao, Yiming; Zhao, Wenming; He, Hang; Zhang, Zhang

2017-01-01

Abstract The Genome Variation Map (GVM; http://bigd.big.ac.cn/gvm/) is a public data repository of genome variations. As a core resource in the BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, GVM dedicates to collect, integrate and visualize genome variations for a wide range of species, accepts submissions of different types of genome variations from all over the world and provides free open access to all publicly available data in support of worldwide research a...

Quantum variational calculus

CERN Document Server

Malinowska, Agnieszka B

2014-01-01

This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of its results is that they are able to deal with nondifferentiable (even discontinuous) functions, which are important in applications. Possible applications in economics are discussed. Economists model time as continuous or discrete. Although individual economic decisions are generally made at discrete time intervals, they may well be less than perfectly synchronized in ways discrete models postulate. On the other hand, the usual assumption that economic activity takes place continuously, is nothing else than a convenient abstraction that in many applications is far from reality. The Hahn quantum calculus helps to bridge the gap between the two families of models: continuous and discrete. Quantum Variational Calculus is self-contained and unified in presentation. It provides an opportunity for an introduction to the quantum calculus of variations fo...

Transcriptome profiling of resistant and susceptible Cavendish banana roots following inoculation with Fusarium oxysporum f. sp. cubense tropical race 4

Directory of Open Access Journals (Sweden)

Li Chun-yu

2012-08-01

Full Text Available Abstract Background Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4, is considered the most lethal disease of Cavendish bananas in the world. The disease can be managed in the field by planting resistant Cavendish plants generated by somaclonal variation. However, little information is available on the genetic basis of plant resistance to Foc TR4. To a better understand the defense response of resistant banana plants to the Fusarium wilt pathogen, the transcriptome profiles in roots of resistant and susceptible Cavendish banana challenged with Foc TR4 were compared. Results RNA-seq analysis generated more than 103 million 90-bp clean pair end (PE reads, which were assembled into 88,161 unigenes (mean size = 554 bp. Based on sequence similarity searches, 61,706 (69.99% genes were identified, among which 21,273 and 50,410 unigenes were assigned to gene ontology (GO categories and clusters of orthologous groups (COG, respectively. Searches in the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG mapped 33,243 (37.71% unigenes to 119 KEGG pathways. A total of 5,008 genes were assigned to plant-pathogen interactions, including disease defense and signal transduction. Digital gene expression (DGE analysis revealed large differences in the transcriptome profiles of the Foc TR4-resistant somaclonal variant and its susceptible wild-type. Expression patterns of genes involved in pathogen-associated molecular pattern (PAMP recognition, activation of effector-triggered immunity (ETI, ion influx, and biosynthesis of hormones as well as pathogenesis-related (PR genes, transcription factors, signaling/regulatory genes, cell wall modification genes and genes with other functions were analyzed and compared. The results indicated that basal defense mechanisms are involved in the recognition of PAMPs, and that high levels of defense-related transcripts may contribute to Foc TR4 resistance in

Vascular Variations Associated with Intracranial Aneurysms.

Science.gov (United States)

Orakdogen, Metin; Emon, Selin Tural; Somay, Hakan; Engin, Taner; Is, Merih; Hakan, Tayfun

2017-01-01

To investigate the vascular variations in patients with intracranial aneurysm in circle of Willis. We used the data on 128 consecutive intracranial aneurysm cases. Cerebral angiography images were analyzed retrospectively. Arteries were grouped as anterior cerebral arterial system (ACS), posterior cerebral arterial system (PCS) and middle cerebral arterial system (MCS) for grouping vascular variations. Lateralization, being single/multiple, gender; and also any connection with accompanying aneurysms" number, localization, dimension, whether bleeding/incidental aneurysm has been inspected. Variations were demonstrated in 57.8% of the cases. The most common variation was A1 variation (34.4%). The rate of variations was 36.7%, 24.2% and 10.2% respectively in ACS, PCS and MCS. MCS variations were significantly higher in males. Anterior communicating artery (ACoA) aneurysm observance rates were significantly higher and posterior communicating artery (PCoA) aneurysm and middle cerebral artery (MCA) aneurysm observance rates were significantly lower when compared to "no ACS variation detected" cases. In "PCS variation detected" cases, PCoA aneurysm observance rates and coexistence of multiple variations were significantly higher. The rate of vascular variations in patients with aneurysms was 57.8%. Arterial hypoplasia and aplasia were the most common variations. ACS was the most common region that variations were located in; they were mostly detected on the right side. Coexistence of ACoA aneurysm was higher than PCoA and MCA aneurysms. In the PCS variations group, PCoA aneurysms were the most common aneurysms that accompanying the variation and multiple variations were more common than in the other two groups. The variations in MCS were most common in males.

Cytoplasmic genetic variation and extensive cytonuclear interactions influence natural variation in the metabolome

DEFF Research Database (Denmark)

Joseph, Bindu; Corwin, Jason A.; Li, Baohua

2013-01-01

Understanding genome to phenotype linkages has been greatly enabled by genomic sequencing. However, most genome analysis is typically confined to the nuclear genome. We conducted a metabolomic QTL analysis on a reciprocal RIL population structured to examine how variation in the organelle genomes...... was a central hub in the epistatic network controlling the plant metabolome. This epistatic influence manifested such that the cytoplasmic background could alter or hide pairwise epistasis between nuclear loci. Thus, cytoplasmic genetic variation plays a central role in controlling natural variation...... in metabolomic networks. This suggests that cytoplasmic genomes must be included in any future analysis of natural variation....

Variation tolerant SoC design

Science.gov (United States)

Kozhikkottu, Vivek J.

The scaling of integrated circuits into the nanometer regime has led to variations emerging as a primary concern for designers of integrated circuits. Variations are an inevitable consequence of the semiconductor manufacturing process, and also arise due to the side-effects of operation of integrated circuits (voltage, temperature, and aging). Conventional design approaches, which are based on design corners or worst-case scenarios, leave designers with an undesirable choice between the considerable overheads associated with over-design and significantly reduced manufacturing yield. Techniques for variation-tolerant design at the logic, circuit and layout levels of the design process have been developed and are in commercial use. However, with the incessant increase in variations due to technology scaling and design trends such as near-threshold computing, these techniques are no longer sufficient to contain the effects of variations, and there is a need to address variations at all stages of design. This thesis addresses the problem of variation-tolerant design at the earliest stages of the design process, where the system-level design decisions that are made can have a very significant impact. There are two key aspects to making system-level design variation-aware. First, analysis techniques must be developed to project the impact of variations on system-level metrics such as application performance and energy. Second, variation-tolerant design techniques need to be developed to absorb the residual impact of variations (that cannot be contained through lower-level techniques). In this thesis, we address both these facets by developing robust and scalable variation-aware analysis and variation mitigation techniques at the system level. The first contribution of this thesis is a variation-aware system-level performance analysis framework. We address the key challenge of translating the per-component clock frequency distributions into a system-level application

Exploring language variation across Europe

DEFF Research Database (Denmark)

Hovy, Dirk; Johannsen, Anders Trærup

2016-01-01

Language varies not only between countries, but also along regional and sociodemographic lines. This variation is one of the driving factors behind language change. However, investigating language variation is a complex undertaking: the more factors we want to consider, the more data we need. Tra...... use of large amounts of data and provides statistical analyses, maps, and interactive features that enable scholars to explore language variation in a data-driven way.......Language varies not only between countries, but also along regional and sociodemographic lines. This variation is one of the driving factors behind language change. However, investigating language variation is a complex undertaking: the more factors we want to consider, the more data we need...... training in both variational linguistics and computational methods, a combination that is still not common. We take a first step here to alleviate the problem by providing an interface to explore large-scale language variation along several socio-demographic factors without programming knowledge. It makes...

Isolation of carrot plant lines with altered carotene contents from gamma irradiated explants

International Nuclear Information System (INIS)

Pawlicki, N.; Sangwan, R.S.; Sangwan-Norreel, B.S.

2001-01-01

irradiated embryos, were always lower compared to controls of the same variety except for one plant in variety 'Scarla' (SC 11 ). The mean carotene level in SC 11 , based on 10 analyses, was 142.8 μg/g compared with 55.9 μg/g in other irradiated plant SC 12 , 65.1 μg/g for the plant regenerated from control somatic embryo (SC 1 ). The difference between SC 1 and SC 12 was not significant, at 5% level, but were significant between SC 1 , and SC 11 . The roots of irradiated somatic embryos of the other two cultivars 'Boltex' and 'Tantal' showed similar carotene levels, mean BOI=117.6 μg/g, and TAI=489.3 μg/g, respectively, but lower than those in plants from non-irradiated somatic embryos. It is concluded that a wide variation in carotene production exists in somaclonal populations derived through somatic embryogenesis with or without gamma-irradiation of carrot. The result is in agreement with the reports that somaclonal variation represents a new source of variability, and therefore, constitutes an additional tool for the breeder

Variational principles

CERN Document Server

Moiseiwitsch, B L

2004-01-01

This graduate-level text's primary objective is to demonstrate the expression of the equations of the various branches of mathematical physics in the succinct and elegant form of variational principles (and thereby illuminate their interrelationship). Its related intentions are to show how variational principles may be employed to determine the discrete eigenvalues for stationary state problems and to illustrate how to find the values of quantities (such as the phase shifts) that arise in the theory of scattering. Chapter-by-chapter treatment consists of analytical dynamics; optics, wave mecha

Pluck or Luck: Does Trait Variation or Chance Drive Variation in Lifetime Reproductive Success?

Science.gov (United States)

Snyder, Robin E; Ellner, Stephen P

2018-04-01

While there has been extensive interest in how intraspecific trait variation affects ecological processes, outcomes are highly variable even when individuals are identical: some are lucky, while others are not. Trait variation is therefore important only if it adds substantially to the variability produced by luck. We ask when trait variation has a substantial effect on variability in lifetime reproductive success (LRS), using two approaches: (1) we partition the variation in LRS into contributions from luck and trait variation and (2) we ask what can be inferred about an individual's traits and with what certainty, given their observed LRS. In theoretical stage- and size-structured models and two empirical case studies, we find that luck usually dominates the variance of LRS. Even when individuals differ substantially in ways that affect expected LRS, unless the effects of luck are substantially reduced (e.g., low variability in reproductive life span or annual fecundity), most variance in lifetime outcomes is due to luck, implying that departures from "null" models omitting trait variation will be hard to detect. Luck also obscures the relationship between realized LRS and individual traits. While trait variation may influence the fate of populations, luck often governs the lives of individuals.

Genome Variation Map: a data repository of genome variations in BIG Data Center.

Science.gov (United States)

Song, Shuhui; Tian, Dongmei; Li, Cuiping; Tang, Bixia; Dong, Lili; Xiao, Jingfa; Bao, Yiming; Zhao, Wenming; He, Hang; Zhang, Zhang

2018-01-04

The Genome Variation Map (GVM; http://bigd.big.ac.cn/gvm/) is a public data repository of genome variations. As a core resource in the BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, GVM dedicates to collect, integrate and visualize genome variations for a wide range of species, accepts submissions of different types of genome variations from all over the world and provides free open access to all publicly available data in support of worldwide research activities. Unlike existing related databases, GVM features integration of a large number of genome variations for a broad diversity of species including human, cultivated plants and domesticated animals. Specifically, the current implementation of GVM not only houses a total of ∼4.9 billion variants for 19 species including chicken, dog, goat, human, poplar, rice and tomato, but also incorporates 8669 individual genotypes and 13 262 manually curated high-quality genotype-to-phenotype associations for non-human species. In addition, GVM provides friendly intuitive web interfaces for data submission, browse, search and visualization. Collectively, GVM serves as an important resource for archiving genomic variation data, helpful for better understanding population genetic diversity and deciphering complex mechanisms associated with different phenotypes. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Genome Variation Map: a data repository of genome variations in BIG Data Center

Science.gov (United States)

Tian, Dongmei; Li, Cuiping; Tang, Bixia; Dong, Lili; Xiao, Jingfa; Bao, Yiming; Zhao, Wenming; He, Hang

2018-01-01

Abstract The Genome Variation Map (GVM; http://bigd.big.ac.cn/gvm/) is a public data repository of genome variations. As a core resource in the BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, GVM dedicates to collect, integrate and visualize genome variations for a wide range of species, accepts submissions of different types of genome variations from all over the world and provides free open access to all publicly available data in support of worldwide research activities. Unlike existing related databases, GVM features integration of a large number of genome variations for a broad diversity of species including human, cultivated plants and domesticated animals. Specifically, the current implementation of GVM not only houses a total of ∼4.9 billion variants for 19 species including chicken, dog, goat, human, poplar, rice and tomato, but also incorporates 8669 individual genotypes and 13 262 manually curated high-quality genotype-to-phenotype associations for non-human species. In addition, GVM provides friendly intuitive web interfaces for data submission, browse, search and visualization. Collectively, GVM serves as an important resource for archiving genomic variation data, helpful for better understanding population genetic diversity and deciphering complex mechanisms associated with different phenotypes. PMID:29069473

Development and Phytochemical Characterization of High Polyphenol Red Lettuce with Anti-Diabetic Properties

Science.gov (United States)

Cheng, Diana M.; Pogrebnyak, Natalia; Kuhn, Peter; Krueger, Christian G.; Johnson, William D.; Raskin, Ilya

2014-01-01

Polyphenol-rich Rutgers Scarlet Lettuce (RSL) (Lactuca sativa L.) was developed through somaclonal variation and selection in tissue culture. RSL may contain among the highest reported contents of polyphenols and antioxidants in the category of common fruits and vegetables (95.6 mg/g dry weight and 8.7 mg/g fresh weight gallic acid equivalents and 2721 µmol/g dry weight and 223 µmol/g fresh weight Trolox equivalents). Three main compounds accumulate at particularly high levels in RSL: chlorogenic acid, up to 27.6 mg/g dry weight, cyanidin malonyl-glucoside, up to 20.5 mg/g dry weight, and quercetin malonyl-glucoside, up to 35.7 mg/g dry weight. Major polyphenolic constituents of RSL have been associated with health promotion as well as anti-diabetic and/or anti-inflammatory activities. Daily oral administration of RSL (100 or 300 mg/kg) for up to eight days acutely reduced hyperglycemia and improved insulin sensitivity in high fat diet-induced obese hyperglycemic mice compared to vehicle (water) control. Data presented here support possible use of RSL as a functional food for the dietary management of diabetes. PMID:24637790

Production of Basella plants resistant to rust by irradiation of seeds and vegetative tissue

International Nuclear Information System (INIS)

Makambila, C.

1997-01-01

Basella is classified in the family Chenopodiaceae or Basellaceae. Also known as African spinach, this plant is consumed in Central Africa and several other African countries. There are two types of varieties grown in Congo: i. a local variety characterized by red leaves and stalks in which the principal way of propagation is from cuttings; ii. a group of varieties which have green or purple leaves and stalks. These varieties are called Basella alba and Basella rubra. These varieties have sexual reproduction. Among the two groups of varieties, the local variety is propagated vegetatively but is resistant to rust, while varieties with green leaves or with purple leaves (B. alba and B. rubra) that are propagated from seed are susceptible to rust. Since hybrid cannot be made by conventional crossing, the following procedures have been adopted to produce plants with disease tolerance: 1. production of resistant variants by irradiation of Basella alba seeds with Cesium 137; 2. production of resistant variants by irradiation of vegetative tissues obtained by culture of meristematic cells of B alba; and 3. obtaining resistant plants through somaclonal variation. 1 tab

Traditional genetic improvement and use of biotechnological techniques in searching of resistance to main fungi pathogens of Musa spp.

Directory of Open Access Journals (Sweden)

Michel Leiva-Mora

2006-07-01

Full Text Available Bananas and plantain are important food staple in human diet, even cooked or consumed fresh. Fungal diseases caused by Fusarium oxysporum f. sp. cubense (Foc and Mycosphaerella fijiensis have threated to distroy Musa spp. Those crops are difficult to breed genetically because they are steriles, do not produce fertil seeds and they are partenocarpic. Genetic crossing by hibridization have been used successfully in FHIA and IITA Musa breeding programs, they have released numerous improved hybrids to those diseases. Plant Biotechnology has developed a set of techniques for Musa micropropagation to increase multiplication rates, healthy and safety plant material for plantation. Mutagenic techniques, somaclonal variation, somatic embryogenesis and more recient genetic transformation have enabled advances and complementation with clasical Musa breeding for searching resistance to principal fungal pathogen of Musa spp. Field evaluation systems to find Musa resistant genotypes to Foc and M. fijiensis have demostrated to be usefull but laborious. Nevertheless to enhance eficacy in selection of promissory genotypes the development of reproducible early evaluation methodologies by using fungal pathogens or their derivates is needed. Key words: evaluation and selection, Fusarium oxysporum, improvement

Development and phytochemical characterization of high polyphenol red lettuce with anti-diabetic properties.

Directory of Open Access Journals (Sweden)

Diana M Cheng

Full Text Available Polyphenol-rich Rutgers Scarlet Lettuce (RSL (Lactuca sativa L. was developed through somaclonal variation and selection in tissue culture. RSL may contain among the highest reported contents of polyphenols and antioxidants in the category of common fruits and vegetables (95.6 mg/g dry weight and 8.7 mg/g fresh weight gallic acid equivalents and 2721 µmol/g dry weight and 223 µmol/g fresh weight Trolox equivalents. Three main compounds accumulate at particularly high levels in RSL: chlorogenic acid, up to 27.6 mg/g dry weight, cyanidin malonyl-glucoside, up to 20.5 mg/g dry weight, and quercetin malonyl-glucoside, up to 35.7 mg/g dry weight. Major polyphenolic constituents of RSL have been associated with health promotion as well as anti-diabetic and/or anti-inflammatory activities. Daily oral administration of RSL (100 or 300 mg/kg for up to eight days acutely reduced hyperglycemia and improved insulin sensitivity in high fat diet-induced obese hyperglycemic mice compared to vehicle (water control. Data presented here support possible use of RSL as a functional food for the dietary management of diabetes.

Search for methylation-sensitive amplification polymorphisms associated with the mantled variant phenotype in oil palm (Elaeis guineensis Jacq).

Science.gov (United States)

Jaligot, E; Beulé, T; Baurens, F-C; Billotte, N; Rival, A

2004-02-01

The methylation-sensitive amplification polymorphism (MSAP) technique has been employed on somatic embryo-derived oil palms (Elaeis guineensis Jacq.) to identify methylation polymorphisms correlated with the "mantled" somaclonal variation. The variant phenotype displays an unstable feminization of male organs in both male and female flowers. Using MSAP, the methylation status of CCGG sites was compared in three normal versus three mantled regenerants sampled in clonal populations obtained through somatic embryogenesis from four genotypically distinct mother palms. Overall, 64 selective primer combinations were used and they have amplified 23 markers exhibiting a differential methylation pattern between the two phenotypes. Our results indicate that CCGG sites are poorly affected by the considerable decrease in global DNA methylation that has been previously associated with the mantled phenotype. Each of the 23 markers isolated in the present study could discriminate between the two phenotypes only when they were from the same genetic origin. This result hampers at the moment the direct use of MSAP markers for the early detection of variants, even though valuable information on putative target sequences will be obtained from a further characterization of these polymorphic markers.

Genetic stability evaluation of quercus suber l. somatic embryogenesis by rapd analysis

International Nuclear Information System (INIS)

Fernandes, P.; Costa, A.; Rocha, A.C.C.; Santos, C.

2011-01-01

A reliable protocol for adult Quercus suber L. somatic embryogenesis (SE) was developed recently. To evaluate the potential use of this protocol in cork oak forest breeding programs, it is essential to guarantee somatic embryos/emblings genetic stability. Random Amplification of Polymorphic DNA (RAPD) is currently used to assess somaclonal variation providing information on genetic variability of the micropropagation process. In this work, SE was induced from adult trees by growing leaf explants on MS medium supplemented with 2,4-D and zeatin. Embling conversion took place on MS medium without growth regulators. DNA from donor tree, somatic embryos and emblings was used to assess genetic variability by RAPD fingerprinting. Fourteen primers produced 165 genetic loci with high quality and reproducibility. Despite somatic embryos originated some poor quality PCR-profiles, replicable and excellent fingerprints were obtained for both donor plant and embling. Results presented no differences among regenerated emblings and donor plant. Hence, the SE protocol used did not induce, up to moment, any genetic variability, confirming data previously obtained with other molecular/genetic techniques, supporting that this protocol may be used to provide true-to-type plants from important forestry species. (author)

Production of Basella plants resistant to rust by irradiation of seeds and vegetative tissue

Energy Technology Data Exchange (ETDEWEB)

Makambila, C [Laboratory of Phytopathology, Faculty of Sciences, Univ. of Brazzaville, Brazzaville (Congo)

1997-12-01

Basella is classified in the family Chenopodiaceae or Basellaceae. Also known as African spinach, this plant is consumed in Central Africa and several other African countries. There are two types of varieties grown in Congo: i. a local variety characterized by red leaves and stalks in which the principal way of propagation is from cuttings; ii. a group of varieties which have green or purple leaves and stalks. These varieties are called Basella alba and Basella rubra. These varieties have sexual reproduction. Among the two groups of varieties, the local variety is propagated vegetatively but is resistant to rust, while varieties with green leaves or with purple leaves (B. alba and B. rubra) that are propagated from seed are susceptible to rust. Since hybrid cannot be made by conventional crossing, the following procedures have been adopted to produce plants with disease tolerance: 1. production of resistant variants by irradiation of Basella alba seeds with Cesium 137; 2. production of resistant variants by irradiation of vegetative tissues obtained by culture of meristematic cells of B alba; and 3. obtaining resistant plants through somaclonal variation. 1 tab.

Biotechnology and genetic optimization of fast-growing hardwoods

Energy Technology Data Exchange (ETDEWEB)

Garton, S.; Syrkin-Wurtele, E.; Griffiths, H.; Schell, J.; Van Camp, L.; Bulka, K. (NPI, Salt Lake City, UT (United States))

1991-02-01

A biotechnology research program was initiated to develop new clones of fast-growing Populus clones resistant to the herbicide glyphosate and resistant to the leaf-spot and canker disease caused by the fungus Septoria musiva. Glyphosate-resistant callus was selected from stem segments cultured in vitro on media supplemented with the herbicide. Plants were regenerated from the glyphosate-resistant callus tissue. A portion of plants reverted to a glyphosate susceptible phenotype during organogenesis. A biologically active filtrate was prepared from S. musiva and influenced fresh weight of Populus callus tissue. Disease-resistant plants were produced through somaclonal variation when shoots developed on stem internodes cultured in vitro. Plantlets were screened for disease symptoms after spraying with a suspension of fungal spores. A frequency of 0.83 percent variant production was observed. Genetically engineered plants were produced after treatment of plant tissue with Agrobacterium tumefasciens strains carrying plasmid genes for antibiotic resistance. Transformers were selected on media enriched with the antibiotic, kanamycin. Presence of foreign DNA was confirmed by Southern blot analysis. Protoplasts of popular were produced but did not regenerate into plant organs. 145 refs., 12 figs., 36 tabs.

Development of somaclones in sugarcane genotype BF-162 and ...

African Journals Online (AJOL)

pris

2012-02-21

Feb 21, 2012 ... Baksha R, Alam R, Karim MZ, Paul SK, Hossain MA, Miah MAS,. Rahman ABMM (2002). In vitro Shoot Tip Culture of Sugarcane. (Saccharum officinarum) Variety Isd 28. Int. Quarterly J. Biotech. 1: 67-72. Brisibe E, Miyake AH, Taniguchi T, Maeda E (1994). Regulation of somatic embryogenesis in long-term ...

General inverse problems for regular variation

DEFF Research Database (Denmark)

Damek, Ewa; Mikosch, Thomas Valentin; Rosinski, Jan

2014-01-01

Regular variation of distributional tails is known to be preserved by various linear transformations of some random structures. An inverse problem for regular variation aims at understanding whether the regular variation of a transformed random object is caused by regular variation of components ...

Variationally Asymptotically Stable Difference Systems

Directory of Open Access Journals (Sweden)

Goo YoonHoe

2007-01-01

Full Text Available We characterize the h-stability in variation and asymptotic equilibrium in variation for nonlinear difference systems via n∞-summable similarity and comparison principle. Furthermore we study the asymptotic equivalence between nonlinear difference systems and their variational difference systems by means of asymptotic equilibria of two systems.

Variational Transition State Theory

Energy Technology Data Exchange (ETDEWEB)

Truhlar, Donald G. [Univ. of Minnesota, Minneapolis, MN (United States)

2016-09-29

This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.

Existence of evolutionary variational solutions via the calculus of variations

Science.gov (United States)

Bögelein, Verena; Duzaar, Frank; Marcellini, Paolo

In this paper we introduce a purely variational approach to time dependent problems, yielding the existence of global parabolic minimizers, that is ∫0T ∫Ω [uṡ∂tφ+f(x,Du)] dx dt⩽∫0T ∫Ω f(x,Du+Dφ) dx dt, whenever T>0 and φ∈C0∞(Ω×(0,T),RN). For the integrand f:Ω×R→[0,∞] we merely assume convexity with respect to the gradient variable and coercivity. These evolutionary variational solutions are obtained as limits of maps depending on space and time minimizing certain convex variational functionals. In the simplest situation, with some growth conditions on f, the method provides the existence of global weak solutions to Cauchy-Dirichlet problems of parabolic systems of the type ∂tu-divDξf(x,Du)=0 in Ω×(0,∞).

Evaluation and Selection of Mutative Artemisia (Artemisia annua L. According to the Altitude Variants

Directory of Open Access Journals (Sweden)

ENDANG GATI LESTARI

2011-03-01

Full Text Available Induction of genetic variant of Artemisia annua L. was conducted through the application of gamma ray irradiation in 2007-2008. The aim was to obtain a plant with high artemisine content ≥ 0.5% and late flowering period of about ≥ 7 month after planting. Tweleve selected genotypes were subsequently examined to gain genetic stability on altitude of 1500, 950, and 540 m asl. The results showed that the plants had shorter flowering age in Cicurug (540 m asl than that of in Pacet (950 m asl and Gunung Putri (1540 m asl. Genotype 8 had the latest age of flowering in the three locations than the other genotypes, however, the growth and biomass were the lowest. Vegetative growth of Artemisia in Pacet and Gunung Putri was better than those in Cicurug. Genotype of 15 in Cicurug and 5A genotype in Gunung Putri and Pacet had higher wet and dry weight than that of two other associates. Based on plant biomass, 5 genotypes from Gunung Putri and Pacet i.e. 1D, 3, 5A, 14, and 15 genotypes were selected, as well as 5 genotypes i.e. 1D, 3, 4, 5A, and 15 genotypes from Cicurug. Analisys on artemisin content successfully obtained 5 selected somaclone lines i.e. 1B, 2, 4, 14, and 3 somaclones.

Early evaluation and on field conditions of resistance to Mycosphaerella fijiensis Morelet of plants from Grande naine (AAA cultivar, obtained through out tissue culture and mutations induction

Directory of Open Access Journals (Sweden)

Lourdes R. García

2003-04-01

Full Text Available The present work was carried out in the Plants Biotechnology Institute of the Central University of Las Villas. The plant material from the cv. Grande Naine (AAA was treated with physical mutagenic agents(gamma radiation 60Co source to induce genetic variability. The behaviour of the population to the black Sigatoka was evaluated. A somaclone was selected by its disease resistance and was in vitro multiplied and the plants were acclimatized to evaluate its behaviour facing the disease on greenhouse conditions and in a second cycle of multiplication in the field. The results showed that in the majority of the plants were not found differences respect cv Grande Naine, just one presented similar reaction to cv. ‘FHIA 18’ (AAAB (partially resistant as for the variable evaluated, being obtained a frequency of 0.018% for this character. This plant was named IBP 446. After 60 days of application of the mycelial homogenized of M. fijiensis in micropropagated plants of this somaclone, differences in the respect affectation states were found at susceptible witness in greenhouse conditions. When plants of the IBP 446 were evaluated in a second cycle of multiplication differences were found with the susceptible control only at flowering, while they behaved similar at susceptible control in the crop. Key words: early detection, breeding, mutation, Black Sigatoka

Genetic Variation in the Nuclear and Organellar Genomes Modulates Stochastic Variation in the Metabolome, Growth, and Defense

Science.gov (United States)

Joseph, Bindu; Corwin, Jason A.; Kliebenstein, Daniel J.

2015-01-01

Recent studies are starting to show that genetic control over stochastic variation is a key evolutionary solution of single celled organisms in the face of unpredictable environments. This has been expanded to show that genetic variation can alter stochastic variation in transcriptional processes within multi-cellular eukaryotes. However, little is known about how genetic diversity can control stochastic variation within more non-cell autonomous phenotypes. Using an Arabidopsis reciprocal RIL population, we showed that there is significant genetic diversity influencing stochastic variation in the plant metabolome, defense chemistry, and growth. This genetic diversity included loci specific for the stochastic variation of each phenotypic class that did not affect the other phenotypic classes or the average phenotype. This suggests that the organism's networks are established so that noise can exist in one phenotypic level like metabolism and not permeate up or down to different phenotypic levels. Further, the genomic variation within the plastid and mitochondria also had significant effects on the stochastic variation of all phenotypic classes. The genetic influence over stochastic variation within the metabolome was highly metabolite specific, with neighboring metabolites in the same metabolic pathway frequently showing different levels of noise. As expected from bet-hedging theory, there was more genetic diversity and a wider range of stochastic variation for defense chemistry than found for primary metabolism. Thus, it is possible to begin dissecting the stochastic variation of whole organismal phenotypes in multi-cellular organisms. Further, there are loci that modulate stochastic variation at different phenotypic levels. Finding the identity of these genes will be key to developing complete models linking genotype to phenotype. PMID:25569687

Induction of somaclonal variation and mutations in sugarcane calli for selecting mutants with resistance to red-rot and tolerance to water-logged conditions

International Nuclear Information System (INIS)

Shaikh, M.A.Q.; Begum, S.; Samad, M.A.; Shmsuzzaman, K.M.

1997-01-01

Immature leaves of cv. 'Isd-16' of sugarcane were cultured on modified MS medium supplemented with 3.0 mg/l 2,4-D for callus induction. The calli were transferred to MS medium supplemented with 5.0 mg/l IAA and 2.0 mg/l KIN for shoot regeneration. The shoots were rooted on MS medium supplemented with 5.0 mg/1NAA and 70 g/l sucrose. The regenerated plants were screened against red-rot disease and water-logged condition in a field. Of the 368 plants inoculated with red-rot pathogen, only one was moderately resistant and two were moderately susceptible. In another set of 500 R 1 plants, six clones were tolerant to water-logged condition. Four week-old callus cultures were irradiated with doses of 2, 3, 4, 5, 6, 7, 8 and 10 Gy gamma-rays. Survival of calli decreased with increase in radiation dose and ranged from 58 to 91%. Regenerated shoots were obtained from all irradiated calli except those treated with 8 and 10 Gy. Shoot regeneration from the irradiated calli ranged from 8 to 50%, and gave 768 R 1 plants. The highest regeneration of plants was obtained from calli treated with 3 Gy. These plants are being grown in a field for screening against red-rot and water-logged conditions. (author). 10 refs, 2 tabs

Induction of somaclonal variation and mutations in sugarcane calli for selecting mutants with resistance to red-rot and tolerance to water-logged conditions

Energy Technology Data Exchange (ETDEWEB)

Shaikh, M A.Q.; Begum, S; Samad, M A; Shmsuzzaman, K M [Bangladesh Inst. of Nuclear Agriculture, Mymensingh (Bangladesh)

1997-07-01

Immature leaves of cv. `Isd-16` of sugarcane were cultured on modified MS medium supplemented with 3.0 mg/l 2,4-D for callus induction. The calli were transferred to MS medium supplemented with 5.0 mg/l IAA and 2.0 mg/l KIN for shoot regeneration. The shoots were rooted on MS medium supplemented with 5.0 mg/1NAA and 70 g/l sucrose. The regenerated plants were screened against red-rot disease and water-logged condition in a field. Of the 368 plants inoculated with red-rot pathogen, only one was moderately resistant and two were moderately susceptible. In another set of 500 R{sub 1} plants, six clones were tolerant to water-logged condition. Four week-old callus cultures were irradiated with doses of 2, 3, 4, 5, 6, 7, 8 and 10 Gy gamma-rays. Survival of calli decreased with increase in radiation dose and ranged from 58 to 91%. Regenerated shoots were obtained from all irradiated calli except those treated with 8 and 10 Gy. Shoot regeneration from the irradiated calli ranged from 8 to 50%, and gave 768 R{sub 1} plants. The highest regeneration of plants was obtained from calli treated with 3 Gy. These plants are being grown in a field for screening against red-rot and water-logged conditions. (author). 10 refs, 2 tabs.

The role of topolins in micropropagation and somaclonal variation of banana cultivars ´Williams´ and ´Grand Naine´ (Musa spp. AAA)

Czech Academy of Sciences Publication Activity Database

Bairu, M. W.; Stirk, W.A.; Doležal, Karel; van Staden, J.

2008-01-01

Roč. 95, č. 3 (2008), s. 373-379 ISSN 0167-6857 R&D Projects: GA ČR GA522/06/0108 Institutional research plan: CEZ:AV0Z50380511 Keywords : Abnormality index * Banana * Micropropagation Subject RIV: ED - Physiology Impact factor: 1.017, year: 2008

Toward Meaningful Manufacturing Variation Data in Design - Feature Based Description of Variation in Manufacturing Processes

DEFF Research Database (Denmark)

Eifler, Tobias; Boorla, Srinivasa Murthy; Howard, Thomas J.

2016-01-01

The need to mitigate the effects of manufacturing variation already in design is nowadays commonly acknowledged and has led to a wide use of predictive modeling techniques, tolerancing approaches, etc. in industry. The trustworthiness of corresponding variation analyses is, however, not ensured...... by the availability of sophisticated methods and tools alone, but does evidently also depend on the accuracy of the input information used. As existing approaches for the description of manufacturing variation focus however, almost exclusively, on monitoring and controlling production processes, there is frequently...... a lack of objective variation data in design. As a result, variation analyses and tolerancing activities rely on numerous assumptions made to fill the gaps of missing or incomplete data. To overcome this hidden subjectivity, a schema for a consistent and standardised description of manufacturing...

Fimbrial phase variation

DEFF Research Database (Denmark)

Khandige, Surabhi; Møller-Jensen, Jakob

2016-01-01

Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question if the fimb......Surface fimbriae of pathogenic Escherichia coli facilitate sensing, adhesion and even invasion of host epithelial cells. While it is known that the pathogen has the potential to express a plethora of fimbrial variants susceptible to rapid phase ON/OFF variation, it is an open question...... if the fimbrial diversity seen at the population level is the product of random stochasticity or a concerted effort based on active communication. Here we discuss the possibility of a mechanism alternative to a stochastic fimbrial phase variation model affecting the dynamics of a heterogeneous population....

Variational principles in physics

CERN Document Server

Basdevant, Jean-Louis

2007-01-01

Optimization under constraints is an essential part of everyday life. Indeed, we routinely solve problems by striking a balance between contradictory interests, individual desires and material contingencies. This notion of equilibrium was dear to thinkers of the enlightenment, as illustrated by Montesquieu’s famous formulation: "In all magistracies, the greatness of the power must be compensated by the brevity of the duration." Astonishingly, natural laws are guided by a similar principle. Variational principles have proven to be surprisingly fertile. For example, Fermat used variational methods to demonstrate that light follows the fastest route from one point to another, an idea which came to be known as Fermat’s principle, a cornerstone of geometrical optics. Variational Principles in Physics explains variational principles and charts their use throughout modern physics. The heart of the book is devoted to the analytical mechanics of Lagrange and Hamilton, the basic tools of any physicist. Prof. Basdev...

Variation Tolerant On-Chip Interconnects

CERN Document Server

Nigussie, Ethiopia Enideg

2012-01-01

This book presents design techniques, analysis and implementation of high performance and power efficient, variation tolerant on-chip interconnects.  Given the design paradigm shift to multi-core, interconnect-centric designs and the increase in sources of variability and their impact in sub-100nm technologies, this book will be an invaluable reference for anyone concerned with the design of next generation, high-performance electronics systems. Provides comprehensive, circuit-level explanation of high-performance, energy-efficient, variation-tolerant on-chip interconnect; Describes design techniques to mitigate problems caused by variation; Includes techniques for design and implementation of self-timed on-chip interconnect, delay variation insensitive communication protocols, high speed signaling techniques and circuits, bit-width independent completion detection and process, voltage and temperature variation tolerance.                          

Water quality, Multivariate statistical techniques, submarine out fall, spatial variation, temporal variation

International Nuclear Information System (INIS)

Garcia, Francisco; Palacio, Carlos; Garcia, Uriel

2012-01-01

Multivariate statistical techniques were used to investigate the temporal and spatial variations of water quality at the Santa Marta coastal area where a submarine out fall that discharges 1 m3/s of domestic wastewater is located. Two-way analysis of variance (ANOVA), cluster and principal component analysis and Krigging interpolation were considered for this report. Temporal variation showed two heterogeneous periods. From December to April, and July, where the concentration of the water quality parameters is higher; the rest of the year (May, June, August-November) were significantly lower. The spatial variation reported two areas where the water quality is different, this difference is related to the proximity to the submarine out fall discharge.

Variational integrators for electric circuits

International Nuclear Information System (INIS)

Ober-Blöbaum, Sina; Tao, Molei; Cheng, Mulin; Owhadi, Houman; Marsden, Jerrold E.

2013-01-01

In this contribution, we develop a variational integrator for the simulation of (stochastic and multiscale) electric circuits. When considering the dynamics of an electric circuit, one is faced with three special situations: 1. The system involves external (control) forcing through external (controlled) voltage sources and resistors. 2. The system is constrained via the Kirchhoff current (KCL) and voltage laws (KVL). 3. The Lagrangian is degenerate. Based on a geometric setting, an appropriate variational formulation is presented to model the circuit from which the equations of motion are derived. A time-discrete variational formulation provides an iteration scheme for the simulation of the electric circuit. Dependent on the discretization, the intrinsic degeneracy of the system can be canceled for the discrete variational scheme. In this way, a variational integrator is constructed that gains several advantages compared to standard integration tools for circuits; in particular, a comparison to BDF methods (which are usually the method of choice for the simulation of electric circuits) shows that even for simple LCR circuits, a better energy behavior and frequency spectrum preservation can be observed using the developed variational integrator

A survey of variational principles

International Nuclear Information System (INIS)

Lewins, J.D.

1993-01-01

In this article survey of variational principles has been given. Variational principles play a significant role in mathematical theory with emphasis on the physical aspects. There are two principals used i.e. to represent the equation of the system in a succinct way and to enable a particular computation in the system to be carried out with greater accuracy. The survey of variational principles has ranged widely from its starting point in the Lagrange multiplier to optimisation principles. In an age of digital computation, these classic methods can be adapted to improve such calculations. We emphasize particularly the advantage of basic finite element methods on variational principles. (A.B.)

The effect of gamma irradiation and ethyl methan sulfonate on somatic embryo formation of soybean (Glycine max L.)

International Nuclear Information System (INIS)

Ragapadmi Purnamaningsih; Ika Mariska; Lestari, E.G.; Sri Hutami; Rossa Yunita

2014-01-01

Soybean is a source of protein and vegetable oil. Global climate change affect the productivity of soybean, so that new cultivars that have superior characteristic can be produced. In vitro techniques through somaclonal variation and mutation is one alternative for obtaining new varieties when genetic material as the material selection is not available. Mutation induction can be performed on embryogenic cell populations using gamma irradiation or chemical compounds, such as Ethyl Methane Sulfonate (EMS). Both of these methods have been widely used to increase the genetic diversity of plants and have produced new clones with superior characteristic. The main component that must be controlled in the implementation of these technologies is somatic cells regeneration after mutation treatment in order to get in vitro shoots. Regeneration methods which are successfully applied to certain varieties, often is not successfully for other varieties of the same species. Some factors that influence it, are such as explants source, genotype, medium composition, genotype, medium composition, etc. Somaclonal variation and mutation treatment can cause cell damage that is sometimes necessary need modifications of the regeneration method that has been produced before. The aim of the experiment was to get cell population and planlet mutation with gamma irradiation and Ethyl Methan Sulfonate (EMS). Young embryozygotic was used as explant came from young pod that was harvested at 12-20 days after fertilization of Willis, Burangrang and Baluran varieties and accession No B 3592. Embryogenic callus induction was done by using MS media with vitamin B5 added with 20 mg/l of 2,4-D and 3% sucrose. The callus were irradiated by gamma rays 400 rad or dilute in EMS solution with 0.1%, 0.3% and 0.5% concentration for 1, 2, and 3 hours. After mutation treatment, the callus were sub culture for seed somatic induction. The results showed that callus formation was influenced by plant genotype. All

Effect of α variation on a prospective experiment to detect variation of me/mp in diatomic molecules

International Nuclear Information System (INIS)

Beloy, K.; Borschevsky, A.; Schwerdtfeger, P.; Flambaum, V. V.

2011-01-01

We consider the influence of variation in the fine structure constant α on a promising experiment proposed by DeMille et al. to search for variation in the electron-to-proton mass ratio μ using diatomic molecules [DeMille et al., Phys. Rev. Lett. 100, 043202 (2008)]. The proposed experiment involves spectroscopically probing the splitting between two nearly degenerate vibrational levels supported by different electronic potentials. Here we demonstrate that this splitting may be equally or more sensitive to variation in α as to variation in μ. For the anticipated experimental precision, this implies that the α variation may not be negligible, as previously assumed, and further suggests that the method could serve as a competitive means to search for α variation as well.

Ladder variational autoencoders

DEFF Research Database (Denmark)

Sønderby, Casper Kaae; Raiko, Tapani; Maaløe, Lars

2016-01-01

Variational autoencoders are powerful models for unsupervised learning. However deep models with several layers of dependent stochastic variables are difficult to train which limits the improvements obtained using these highly expressive models. We propose a new inference model, the Ladder...... Variational Autoencoder, that recursively corrects the generative distribution by a data dependent approximate likelihood in a process resembling the recently proposed Ladder Network. We show that this model provides state of the art predictive log-likelihood and tighter log-likelihood lower bound compared...

Ladder Variational Autoencoder

DEFF Research Database (Denmark)

Sønderby, Casper Kaae; Raiko, Tapani; Maaløe, Lars

2016-01-01

Variational autoencoders are powerful models for unsupervised learning. However deep models with several layers of dependent stochastic variables are difficult to train which limits the improvements obtained using these highly expressive models. We propose a new inference model, the Ladder...... Variational Autoencoder, that recursively corrects the generative distribution by a data dependent approximate likelihood in a process resembling the recently proposed Ladder Network. We show that this model provides state of the art predictive log-likelihood and tighter log-likelihood lower bound compared...

Individual diet variation in a marine fish assemblage: Optimal Foraging Theory, Niche Variation Hypothesis and functional identity

Science.gov (United States)

Cachera, M.; Ernande, B.; Villanueva, M. C.; Lefebvre, S.

2017-02-01

Individual diet variation (i.e. diet variation among individuals) impacts intra- and inter-specific interactions. Investigating its sources and relationship with species trophic niche organization is important for understanding community structure and dynamics. Individual diet variation may increase with intra-specific phenotypic (or "individual state") variation and habitat variability, according to Optimal Foraging Theory (OFT), and with species trophic niche width, according to the Niche Variation Hypothesis (NVH). OFT proposes "proximate sources" of individual diet variation such as variations in habitat or size whereas NVH relies on "ultimate sources" related to the competitive balance between intra- and inter-specific competitions. The latter implies as a corollary that species trophic niche overlap, taken as inter-specific competition measure, decreases as species niche width and individual niche variation increase. We tested the complementary predictions of OFT and NVH in a marine fish assemblage using stomach content data and associated trophic niche metrics. The NVH predictions were tested between species of the assemblage and decomposed into a between- and a within-functional group component to assess the potential influence of species' ecological function. For most species, individual diet variation and niche overlap were consistently larger than expected. Individual diet variation increased with intra-specific variability in individual state and habitat, as expected from OFT. It also increased with species niche width but in compliance with the null expectation, thus not supporting the NVH. In contrast, species niche overlap increased significantly less than null expectation with both species niche width and individual diet variation, supporting NVH corollary. The between- and within-functional group components of the NVH relationships were consistent with those between species at the assemblage level. Changing the number of prey categories used to

Techniques to assess biological variation in destructive data

NARCIS (Netherlands)

Tijskens, L.M.M.; Schouten, R.E.; Jongbloed, G.; Konopacki, P.J.

2018-01-01

Variation is present in all measured data, due to variation between individuals (biological variation) and variation induced by the measuring system (technical variation). Biological variation present in experimental data is not the result of a random process but strictly subject to deterministic

Non-storm irregular variation of the Dst index

Directory of Open Access Journals (Sweden)

S. Nakano

2012-01-01

Full Text Available The Dst index has a long-term variation that is not associated with magnetic storms. We estimated the long-term non-storm component of the Dst variation by removing the short-term variation related to magnetic storms. The results indicate that the variation of the non-storm component includes not only a seasonal variation but also an irregular variation. The irregular long-term variation is likely to be due to an anti-correlation with the long-term variation of solar-wind activity. In particular, a clear anti-correlation is observed between the non-storm component of Dst and the long-term variation of the solar-wind dynamic pressure. This means that in the long term, the Dst index tends to increase when the solar-wind dynamic pressure decreases. We interpret this anti-correlation as an indication that the long-term non-storm variation of Dst is influenced by the tail current variation. The long-term variation of the solar-wind dynamic pressure controls the plasma sheet thermal pressure, and the change of the plasma sheet thermal pressure would cause the non-storm tail current variation, resulting in the non-storm variation of Dst.

Solution of problems in calculus of variations via He's variational iteration method

International Nuclear Information System (INIS)

Tatari, Mehdi; Dehghan, Mehdi

2007-01-01

In the modeling of a large class of problems in science and engineering, the minimization of a functional is appeared. Finding the solution of these problems needs to solve the corresponding ordinary differential equations which are generally nonlinear. In recent years He's variational iteration method has been attracted a lot of attention of the researchers for solving nonlinear problems. This method finds the solution of the problem without any discretization of the equation. Since this method gives a closed form solution of the problem and avoids the round off errors, it can be considered as an efficient method for solving various kinds of problems. In this research He's variational iteration method will be employed for solving some problems in calculus of variations. Some examples are presented to show the efficiency of the proposed technique

Seasonal variation in sports participation.

Science.gov (United States)

Schüttoff, Ute; Pawlowski, Tim

2018-02-01

This study explores indicators describing socio-demographics, sports participation characteristics and motives which are associated with variation in sports participation across seasons. Data were drawn from the German Socio-Economic Panel which contains detailed information on the sports behaviour of adults in Germany. Overall, two different measures of seasonal variation are developed and used as dependent variables in our regression models. The first variable measures the coefficient of (seasonal) variation in sport-related energy expenditure per week. The second variable measures whether activity drops below the threshold as defined by the World Health Organization (WHO). Results suggest that the organisational setting, the intensity and number of sports practised, and the motive for participation are strongly correlated with the variation measures used. For example, both, participation in a sports club and a commercial facility, are associated with reduced seasonal variation and a significantly higher probability of participating at a volume above the WHO threshold across all seasons. These findings give some impetus for policymaking and the planning of sports programmes as well as future research directions.

Environmental variation partitioned into separate heritable components

DEFF Research Database (Denmark)

Ørsted, Michael; Rohde, Palle Duun; Hoffmann, Ary A

2018-01-01

Trait variation is normally separated into genetic and environmental components, yet genetic factors also control the expression of environmental variation, encompassing plasticity across environmental gradients and within-environment responses. We defined four components of environmental variation......: plasticity across environments, variability in plasticity, variation within environments, and differences in within-environment variation across environments. We assessed these components for cold tolerance across five rearing temperatures using the Drosophila melanogaster Genetic Reference Panel (DGRP...

Coarse Grained Exponential Variational Autoencoders

KAUST Repository

Sun, Ke; Zhang, Xiangliang

2017-01-01

Variational autoencoders (VAE) often use Gaussian or category distribution to model the inference process. This puts a limit on variational learning because this simplified assumption does not match the true posterior distribution, which is usually

Frequency variations of discrete cranial traits in major human populations. I. Supernumerary ossicle variations.

Science.gov (United States)

Hanihara, T; Ishida, H

2001-06-01

Four supernumerary ossicle variations-the ossicle at the lambda, the parietal notch bone, the asterionic bone, and the occipitomastoid bone-were examined for laterality differences, intertrait correlations, sex differences, and between group variations in the samples from around the world. Significant laterality differences were not detected in almost all samples. In some pairs of traits, significant association of occurrence were found. Several geographic samples were sexually dimorphic with respect to the asterionic bone and to a lesser extent for the parietal notch bone. East/Northeast Asians including the Arctic populations in general had lower frequencies of the 4 accessory ossicles. Australians, Melanesians and the majority of the New World peoples, on the other hand, generally had high frequencies. In the western hemisphere of the Old World, Subsaharan Africans had relatively high frequencies. Except for the ossicle at the lambda, the distribution pattern in incidence showed clinal variation from south to north. Any identifiable adaptive value related to environmental or subsistence factors may be expressed in such clinal variation. This may allow us to hypothesise that not only mechanical factors but a founder effect, genetic drift, and population structure could have been the underlying causes for interregional variation and possible clines in the incidences of the accessory ossicles.

Intraspecific variation in social organization by genetic variation, developmental plasticity, social flexibility or entirely extrinsic factors.

Science.gov (United States)

Schradin, Carsten

2013-05-19

Previously, it was widely believed that each species has a specific social organization, but we know now that many species show intraspecific variation in their social organization. Four different processes can lead to intraspecific variation in social organization: (i) genetic variation between individuals owing to local adaptation (between populations) or evolutionarily stable strategies within populations; (ii) developmental plasticity evolved in long-term (more than one generation) unpredictable and short-term (one generation) predictable environments, which is mediated by organizational physiological effects during early ontogeny; (iii) social flexibility evolved in highly unpredictable environments, which is mediated by activational physiological effects in adults; (iv) entirely extrinsic factors such as the death of a dominant breeder. Variation in social behaviour occurs between individuals in the case of genetic variation and developmental plasticity, but within individuals in the case of social flexibility. It is important to study intraspecific variation in social organization to understand the social systems of species because it reveals the mechanisms by which species can adapt to changing environments, offers a useful tool to study the ultimate and proximate causes of sociality, and is an interesting phenomenon by itself that needs scientific explanation.

Solar ultraviolet irradiance variations: a review

International Nuclear Information System (INIS)

Lean, J.

1987-01-01

Despite the geophysical importance of solar ultraviolet radiation, specific aspects of its temporal variations have not yet been adequately determined experimentally, nor are the mechanisms for the variability completely understood. Satellite observations have verified the reality of solar ultraviolet irradiance variations over time scales of days and months, and model calculations have confirmed the association of these short-term variations with the evolution and rotation of regions of enhanced magnetic activity on the solar disc. However, neither rocket nor satellite measurements have yet been made with sufficient accuracy and regularity to establish unequivocally the nature of the variability over the longer time of the 11-year solar cycle. The comparative importance for the long-term variations of local regions of enhanced magnetic activity and global scale activity perturbations is still being investigated. Solar ultraviolet irradiance variations over both short and long time scales are reviewed, with emphasis on their connection to solar magnetic activity. Correlations with ground-based measures of solar variability are examined because of the importance of the ground-based observations as historical proxies of ultraviolet irradiance variations. Current problems in understanding solar ultraviolet irradiance variations are discussed, and the measurements planned for solar cycle 22, which may resolve these problems, are briefly described. copyright American Geophysical Union 1987

Accommodating variation: dialects, idiolects, and speech processing.

Science.gov (United States)

Kraljic, Tanya; Brennan, Susan E; Samuel, Arthur G

2008-04-01

Listeners are faced with enormous variation in pronunciation, yet they rarely have difficulty understanding speech. Although much research has been devoted to figuring out how listeners deal with variability, virtually none (outside of sociolinguistics) has focused on the source of the variation itself. The current experiments explore whether different kinds of variation lead to different cognitive and behavioral adjustments. Specifically, we compare adjustments to the same acoustic consequence when it is due to context-independent variation (resulting from articulatory properties unique to a speaker) versus context-conditioned variation (resulting from common articulatory properties of speakers who share a dialect). The contrasting results for these two cases show that the source of a particular acoustic-phonetic variation affects how that variation is handled by the perceptual system. We also show that changes in perceptual representations do not necessarily lead to changes in production.

Variational transition state theory

International Nuclear Information System (INIS)

Truhlar, D.G.

1986-01-01

This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. They have developed and implemented several practical versions of variational transition state theory (VTST), namely canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (μVT). They have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small-curvature semiclassical adiabatic (SCSA), large-curvature version-3 (LC3), and least-action (LA) approximations. They have applied the methods to thermal rate constants, using transmission coefficients based on ground-state tunneling, and they have also presented and applied adiabatic and diabatic extensions to calculated rate constants for vibrationally excited reactants. Their general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of their work is the determination or modeling, semi-empirically and/or from electronic structure calculations, of potential energy surfaces

Influence of Design Variations on Systems Performance

Science.gov (United States)

Tumer, Irem Y.; Stone, Robert B.; Huff, Edward M.; Norvig, Peter (Technical Monitor)

2000-01-01

High-risk aerospace components have to meet very stringent quality, performance, and safety requirements. Any source of variation is a concern, as it may result in scrap or rework. poor performance, and potentially unsafe flying conditions. The sources of variation during product development, including design, manufacturing, and assembly, and during operation are shown. Sources of static and dynamic variation during development need to be detected accurately in order to prevent failure when the components are placed in operation. The Systems' Health and Safety (SHAS) research at the NASA Ames Research Center addresses the problem of detecting and evaluating the statistical variation in helicopter transmissions. In this work, we focus on the variations caused by design, manufacturing, and assembly of these components, prior to being placed in operation (DMV). In particular, we aim to understand and represent the failure and variation information, and their correlation to performance and safety and feed this information back into the development cycle at an early stage. The feedback of such critical information will assure the development of more reliable components with less rework and scrap. Variations during design and manufacturing are a common source of concern in the development and production of such components. Accounting for these variations, especially those that have the potential to affect performance, is accomplished in a variety ways, including Taguchi methods, FMEA, quality control, statistical process control, and variation risk management. In this work, we start with the assumption that any of these variations can be represented mathematically, and accounted for by using analytical tools incorporating these mathematical representations. In this paper, we concentrate on variations that are introduced during design. Variations introduced during manufacturing are investigated in parallel work.

Avaliação por RAPD de plantas de abacaxizeiro cultivar Smooth Cayenne derivadas do seccionamento do talo e cultura de tecidos Evaluation of pineapple plants cultivar Smooth Cayenne from peduncle division and tissue culture by RAPD

Directory of Open Access Journals (Sweden)

MARIA VITÓRIA CECCHETTI GOTTARDI

2002-04-01

least 18 months to obtain the new seedlings. By RAPD analysis of plants obtained by tissue culture were observed different patterns in some samples, those could be related to somaclonal variation.

Normal variation of hepatic artery

International Nuclear Information System (INIS)

Kim, Inn; Nam, Myung Hyun; Rhim, Hyun Chul; Koh, Byung Hee; Seo, Heung Suk; Kim, Soon Yong

1987-01-01

This study was an analyses of blood supply of the liver in 125 patients who received hepatic arteriography and abdominal aortography from Jan. 1984 to Dec. 1986 at the Department of Radiology of Hanyang University Hospital. A. Variations in extrahepatic arteries: 1. The normal extrahepatic artery pattern occurred in 106 of 125 cases (84.8%) ; Right hepatic and left hepatic arteries arising from the hepatic artery proper and hepatic artery proper arising from the common hepatic artery. 2. The most common type of variation of extrahepatic artery was replaced right hepatic artery from superior mesenteric artery: 6 of 125 cases (4.8%). B. Variations in intrahepatic arteries: 1. The normal intrahepatic artery pattern occurred in 83 of 125 cases (66.4%). Right hepatic and left hepatic arteries arising from the hepatic artery proper and middle hepatic artery arising from lower portion of the umbilical point of left hepatic artery. 2. The most common variation of intrahepatic arteries was middle hepatic artery. 3. Among the variation of middle hepatic artery; Right, middle and left hepatic arteries arising from the same location at the hepatic artery proper was the most common type; 17 of 125 cases (13.6%)

Diural TSH variations in hypothyroidism.

Science.gov (United States)

Weeke, J; Laurberg, P

1976-07-01

There is a circadian variation in serum TSH in euthyroid subjects. A similar diurnal variation has been demonstrated in patients with hypothyroidism. In the present study the 24-hour pattern of serum TSH was investigated in eight patients with hypothyroidism of varying severity and in five hypothyroid patients treated with thyroxine (T4). There was a circadian variation in serum TSH in patients with hypothyroidism of moderate degree, and in patients treated for severe hypothyrodism with thyroxine. The pattern was similar to that found in normal subjects, i.e., low TSH levels in the daytime and higher levels at night. In severely hypothyroid patients, no diurnal variation in serum TSH was observed. A practical consequence is that blood samples for TSH measurements in patients with moderately elevated TSH levels are best taken after 1100 h, when the low day levels are reached.

Identification and evaluation of two diagnostic markers linked to Fusarium wilt resistance (race 4) in banana (Musa spp.).

Science.gov (United States)

Wang, Wei; Hu, Yulin; Sun, Dequan; Staehelin, Christian; Xin, Dawei; Xie, Jianghui

2012-01-01

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubense race 4 (FOC4) results in vascular tissue damage and ultimately death of banana (Musa spp.) plants. Somaclonal variants of in vitro micropropagated banana can hamper success in propagation of genotypes resistant to FOC4. Early identification of FOC4 resistance in micropropagated banana plantlets is difficult, however. In this study, we identified sequence-characterized amplified region (SCAR) markers of banana associated with resistance to FOC4. Using pooled DNA from resistant or susceptible genotypes and 500 arbitrary 10-mer oligonucleotide primers, 24 random amplified polymorphic DNA (RAPD) products were identified. Two of these RAPD markers were successfully converted to SCAR markers, called ScaU1001 (GenBank accession number HQ613949) and ScaS0901 (GenBank accession number HQ613950). ScaS0901 and ScaU1001 could be amplified in FOC4-resistant banana genotypes ("Williams 8818-1" and Goldfinger), but not in five tested banana cultivars susceptible to FOC4. The two SCAR markers were then used to identify a somaclonal variant of the genotype "Williams 8818-1", which lost resistance to FOC4. Hence, the identified SCAR markers can be applied for a rapid quality control of FOC4-resistant banana plantlets immediately after the in vitro micropropagation stage. Furthermore, ScaU1001 and ScaS0901 will facilitate marker-assisted selection of new banana cultivars resistant to FOC4.

Comparing variation across European countries

DEFF Research Database (Denmark)

Thygesen, Lau C; Baixauli-Pérez, Cristobal; Librero-López, Julián

2015-01-01

BACKGROUND: In geographical studies, population distribution is a key issue. An unequal distribution across units of analysis might entail extra-variation and produce misleading conclusions on healthcare performance variations. This article aims at assessing the impact of building more homogeneou...

Variation across mitochondrial gene trees provides evidence for systematic error: How much gene tree variation is biological?

Science.gov (United States)

Richards, Emilie J; Brown, Jeremy M; Barley, Anthony J; Chong, Rebecca A; Thomson, Robert C

2018-02-19

The use of large genomic datasets in phylogenetics has highlighted extensive topological variation across genes. Much of this discordance is assumed to result from biological processes. However, variation among gene trees can also be a consequence of systematic error driven by poor model fit, and the relative importance of biological versus methodological factors in explaining gene tree variation is a major unresolved question. Using mitochondrial genomes to control for biological causes of gene tree variation, we estimate the extent of gene tree discordance driven by systematic error and employ posterior prediction to highlight the role of model fit in producing this discordance. We find that the amount of discordance among mitochondrial gene trees is similar to the amount of discordance found in other studies that assume only biological causes of variation. This similarity suggests that the role of systematic error in generating gene tree variation is underappreciated and critical evaluation of fit between assumed models and the data used for inference is important for the resolution of unresolved phylogenetic questions.

Matter tensor from the Hilbert variational principle

International Nuclear Information System (INIS)

Pandres, D. Jr.

1976-01-01

We consider the Hilbert variational principle which is conventionally used to derive Einstein's equations for the source-free gravitational field. We show that at least one version of the equivalence principle suggests an alternative way of performing the variation, resulting in a different set of Einstein equations with sources automatically present. This illustrates a technique which may be applied to any theory that is derived from a variational principle and that admits a gauge group. The essential point is that, if one first imposes a gauge condition and then performs the variation, one obtains field equations with source terms which do not appear if one first performs the variation and then imposes the gauge condition. A second illustration is provided by the variational principle conventionally used to derive Maxwell's equations for the source-free electromagnetic field. If one first imposes the Lorentz gauge condition and then performs the variation, one obtains Maxwell's equations with sources present

[Correlation of intraocular pressure variation after visual field examination with 24-hour intraocular pressure variations in primary open-angle glaucoma].

Science.gov (United States)

Noro, Takahiko; Nakamoto, Kenji; Sato, Makoto; Yasuda, Noriko; Ito, Yoshinori; Ogawa, Shumpei; Nakano, Tadashi; Tsuneoka, Hiroshi

2014-10-01

We retrospectively examined intraocular pressure variations after visual field examination in primary open angle glaucoma (POAG), together with its influencing factors and its association with 24-hour intraocular pressure variations. Subjects were 94 eyes (52 POAG patients) subjected to measurements of 24-hour intraocular pressure and of changes in intraocular pressure after visual field examination using a Humphrey Visual Field Analyzer. Subjects were classified into three groups according to the magnitude of variation (large, intermediate and small), and 24-hour intraocular pressure variations were compared among the three groups. Factors influencing intraocular pressure variations after visual field examination and those associated with the large variation group were investigated. Average intraocular pressure variation after visual field examination was -0.28 ± 1.90 (range - 6.0(-) + 5.0) mmHg. No significant influencing factors were identified. The intraocular pressure at 3 a.m. was significantly higher in the large variation group than other two groups (p field examination. Increases in intraocular pressure during the night might be associated with large intraocular pressure variations after visual field examination.

On Gap Functions for Quasi-Variational Inequalities

Directory of Open Access Journals (Sweden)

Kouichi Taji

2008-01-01

Full Text Available For variational inequalities, various merit functions, such as the gap function, the regularized gap function, the D-gap function and so on, have been proposed. These functions lead to equivalent optimization formulations and are used to optimization-based methods for solving variational inequalities. In this paper, we extend the regularized gap function and the D-gap functions for a quasi-variational inequality, which is a generalization of the variational inequality and is used to formulate generalized equilibrium problems. These extensions are shown to formulate equivalent optimization problems for quasi-variational inequalities and are shown to be continuous and directionally differentiable.

Exploiting natural variation in Arabidopsis

NARCIS (Netherlands)

Molenaar, J.A.; Keurentjes, J.J.B.; Sanchez-Serrano, J.J.; Salinas, J.

2014-01-01

Natural variation for many traits is present within the species Arabidopsis thaliana. This chapter describes the use of natural variation to elucidate genes underlying the regulation of quantitative traits. It deals with the development and use of mapping populations, the detection and handling of

The four variational principles of mechanics

International Nuclear Information System (INIS)

Gray, C.G.; Karl, G.; Novikov, V.A.

1996-01-01

We argue that there are four basic forms of the variational principles of mechanics: Hamilton close-quote s least action principle (HP), the generalized Maupertuis principle (MP), and their two reciprocal principles, RHP and RMP. This set is invariant under reciprocity and Legendre transformations. One of these forms (HP) is in the literature: only special cases of the other three are known. The generalized MP has a weaker constraint compared to the traditional formulation, only the mean energy bar E is kept fixed between virtual paths. This reformulation of MP alleviates several weaknesses of the old version. The reciprocal Maupertuis principle (RMP) is the classical limit of Schroedinger close-quote s variational principle of quantum mechanics, and this connection emphasizes the importance of the reciprocity transformation for variational principles. Two unconstrained formulations (UHP and UMP) of these four principles are also proposed, with completely specified Lagrange multipliers Percival close-quote s variational principle for invariant tori and variational principles for scattering orbits are derived from the RMP. The RMP is very convenient for approximate variational solutions to problems in mechanics using Ritz type methods Examples are provided. Copyright copyright 1996 Academic Press, Inc

Observer variation in skeletal radiology

Energy Technology Data Exchange (ETDEWEB)

Cockshott, W.P.; Park, W.M.

1983-08-01

The factors that affect observer variation in bone radiology are analysed from data in the literature and on the basis of studies carried out at McMaster University on the hands and sacroiliac joints. A plea is made for presenting results in terms of Kappa statistics so that agreement due purely to chance is eliminated. In the conclusions the main variables that affect concordance are listed so that strategies can be developed to reduce observer variation. This is important in serial studies to ensure that the observer variations are smaller than the effect one wishes to measure.

Variation, structure and norms

DEFF Research Database (Denmark)

Harder, Peter

2014-01-01

in linguistics: those that see linguistic norms as antithetical to a descriptive and variational linguistics. Once such a re-evaluation has taken place, however, the social recontextualization of cognition will enable linguistics (including sociolinguistics as an integral part), to eliminate the cracks...... that an evolutionary account can reintegrate the opposed fragments into a whole picture that puts each of them in their ‘ecological position’ with respect to each other. Empirical usage facts should be seen in the context of operational norms in relation to which actual linguistic choices represent adaptations....... Variational patterns should be seen in the context of structural categories without which there would be only ‘differences’ rather than variation. And emergence, individual choice, and flux should be seen in the context of the individual’s dependence on lineages of community practice sustained by collective...

Technical aspects in understanding effects of gamma irradiation on flower colour changes in Dendrobium Sonia

International Nuclear Information System (INIS)

Sakinah Ariffin; Azhar Mohammad; Ratnam, W.

2012-01-01

Colour is one of the most important traits in orchids and has created great interest in breeding programmes. Gamma irradiation is an alternative way for generation of somaclonal variation for new flower colours. Phenotypic changes are usually observed during screening and selection of mutants. Understanding of targeted gene expression level and evaluation of the changes facilitate in the development of functional markers for selection of desired flower colour mutants. Four Dendrobium orchid sequences (NCBI accessions: AM490639, AY41319, FM209429 and DQ462460) were selected to design gene specific primers based on information for chalcone synthase (CHS) from NCBI database. Quantitative real-time PCR (qPCR) was used to understand flower colour expression quantitatively derived from the CHS gene activities in different flower tissues (petal and sepal) from control Dendrobium Sonia (red purple), mutant DS 35-1/M (purple pink) and mutant DS 35-WhiteA. It was found that expression of CHS gene was highest in sepals of white flowers and lowest in both sepals and petals of purple pink flowers. Genomic DNA was amplified and PCR products were sequenced, aligned and compared. Sequence variations of CHS partial gene in Dendrobium Sonia mutants with different flower colour showed that two protein positions have been changed as compared to the control. These non-synonymous mutations may have contributed to the colour alterations in the white and purple pink mutants. This paper describes important procedures to quantify gene expression such as RNA isolation (quantity and quality), cDNA synthesis and primer design steps for CHS genes. (author)

Do key dimensions of seed and seedling functional trait variation capture variation in recruitment probability?

Science.gov (United States)

1. Plant functional traits provide a mechanistic basis for understanding ecological variation among plant species and the implications of this variation for species distribution, community assembly and restoration. 2. The bulk of our functional trait understanding, however, is centered on traits rel...

General quantum variational calculus

Directory of Open Access Journals (Sweden)

Artur M. C. Brito da Cruz

2018-02-01

Full Text Available We develop a new variational calculus based in the general quantum difference operator recently introduced by Hamza et al. In particular, we obtain optimality conditions for generalized variational problems where the Lagrangian may depend on the endpoints conditions and a real parameter, for the basic and isoperimetric problems, with and without fixed boundary conditions. Our results provide a generalization to previous results obtained for the $q$- and Hahn-calculus.

Generalized quasi variational inequalities

Energy Technology Data Exchange (ETDEWEB)

Noor, M.A. [King Saud Univ., Riyadh (Saudi Arabia)

1996-12-31

In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.

Convergence analysis of variational and non-variational multigrid algorithms for the Laplace-Beltrami operator

KAUST Repository

Bonito, Andrea

2012-09-01

We design and analyze variational and non-variational multigrid algorithms for the Laplace-Beltrami operator on a smooth and closed surface. In both cases, a uniform convergence for the V -cycle algorithm is obtained provided the surface geometry is captured well enough by the coarsest grid. The main argument hinges on a perturbation analysis from an auxiliary variational algorithm defined directly on the smooth surface. In addition, the vanishing mean value constraint is imposed on each level, thereby avoiding singular quadratic forms without adding additional computational cost. Numerical results supporting our analysis are reported. In particular, the algorithms perform well even when applied to surfaces with a large aspect ratio. © 2011 American Mathematical Society.

Micropropagation of Phalaenopsis orchids via protocorms and protocorm-like bodies.

Science.gov (United States)

Paek, Kee Yoeup; Hahn, Eun Joo; Park, So Young

2011-01-01

Phalaenopsis orchids have high economic value in the floriculture industry. Hybridization or cross-pollination in the breeding program have proven to be very reliable techniques for the production of a wide range of successful cultivars with attractive combinations of spray length, bud number, flower color and type, fragrance, seasonality, and compactness. In vitro propagation makes it possible to clonally mass propagate hybrids of commercial value and conserved species. However, in vitro culture technologies are still a challenge because of the slow growth of plantlets, low multiplication rate, poor rooting, and somaclonal variation. Although seed-raised plants can be used for conservation and breeding for the selection of superior features, genetic characteristics including seasonality, inflorescence, flower color, and type are not uniform. In this regard, micropropagation through protocorm-like bodies obtained from germinating embryos and somatic tissues is an important strategy in obtaining genetically stable plants and the improvement of quality. However, not all genotypes of Phalaenopsis respond to the same protocol under the same culture conditions and often result in the development of undesirable characteristics. In this chapter, plantlet production in Phalaenopsis orchids via the culture of protocorms from seeds and protocorm-like bodies from leaf sections and root tips are detailed.

Variational integrators in plasma physics

International Nuclear Information System (INIS)

Kraus, Michael

2013-01-01

To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

Variation as a main feature of norm

Directory of Open Access Journals (Sweden)

S. Poladova

2017-09-01

Full Text Available The past half-century has witnessed remarkable growth in the study of language variation, and it has now become a highly productive subfield of research in sociolinguistics. Variability is everywhere in language, from the unique details in each production of a sound or sign to the auditory or visual processing of the linguistic signal. All languages that we can observe today show variation; what is more, they vary in identical ways, namely geographically and socially. It’s no secret that languages like English are full of variation. So, the aim of the article is to detect the reasons of variation and to uncover rates of usage of different free variations for a given set of lexical items. The research work is carried out by using the descriptive, comparative methods by subjecting to analysis the specific language materials. The discovery of law of variation became a starting point for the evolution of linguistics. The problem of search of variation facts and its role in the functioning of language system concerns many specialists from the outset. The scope of the investigation was to set up a system out of chaos of phenomena. Currently, the fact of conditionality of variation by system relations existing in the language is considered to be established.

Genetic Variation in Cardiomyopathy and Cardiovascular Disorders.

Science.gov (United States)

McNally, Elizabeth M; Puckelwartz, Megan J

2015-01-01

With the wider deployment of massively-parallel, next-generation sequencing, it is now possible to survey human genome data for research and clinical purposes. The reduced cost of producing short-read sequencing has now shifted the burden to data analysis. Analysis of genome sequencing remains challenged by the complexity of the human genome, including redundancy and the repetitive nature of genome elements and the large amount of variation in individual genomes. Public databases of human genome sequences greatly facilitate interpretation of common and rare genetic variation, although linking database sequence information to detailed clinical information is limited by privacy and practical issues. Genetic variation is a rich source of knowledge for cardiovascular disease because many, if not all, cardiovascular disorders are highly heritable. The role of rare genetic variation in predicting risk and complications of cardiovascular diseases has been well established for hypertrophic and dilated cardiomyopathy, where the number of genes that are linked to these disorders is growing. Bolstered by family data, where genetic variants segregate with disease, rare variation can be linked to specific genetic variation that offers profound diagnostic information. Understanding genetic variation in cardiomyopathy is likely to help stratify forms of heart failure and guide therapy. Ultimately, genetic variation may be amenable to gene correction and gene editing strategies.

MDCT evaluation of sternal variations: Pictorial essay

International Nuclear Information System (INIS)

Duraikannu, Chary; Noronha, Olma V; Sundarrajan, Pushparajan

2016-01-01

Sternal variations and anomalies have been identified in the past during autopsy or cadaveric studies. Recently, an increasing number of minor sternal variations have been reported with the advent of multidetector computed tomography (CT). Although there are many sternal variations that occur with varying appearance and prevalence, most of them are not recognized or are underreported during routine imaging of thorax. Identification of sternal variations is important to differentiate from pathological conditions and to prevent fatal complications prior to sternal interventions like marrow aspiration or acupuncture. This article aims to describe the minor and asymptomatic sternal variations by multidetector CT and their clinical significance

General strongly nonlinear variational inequalities

International Nuclear Information System (INIS)

Siddiqi, A.H.; Ansari, Q.H.

1990-07-01

In this paper we develop iterative algorithms for finding approximate solutions for new classes of variational and quasi-variational inequalities which include, as special case, some known results in this field. It is shown that the solutions of the iterative schemes converge to the exact solutions. (author). 15 refs

HGVA: the Human Genome Variation Archive

OpenAIRE

Lopez, Javier; Coll, Jacobo; Haimel, Matthias; Kandasamy, Swaathi; Tarraga, Joaquin; Furio-Tari, Pedro; Bari, Wasim; Bleda, Marta; Rueda, Antonio; Gr?f, Stefan; Rendon, Augusto; Dopazo, Joaquin; Medina, Ignacio

2017-01-01

Abstract High-profile genomic variation projects like the 1000 Genomes project or the Exome Aggregation Consortium, are generating a wealth of human genomic variation knowledge which can be used as an essential reference for identifying disease-causing genotypes. However, accessing these data, contrasting the various studies and integrating those data in downstream analyses remains cumbersome. The Human Genome Variation Archive (HGVA) tackles these challenges and facilitates access to genomic...

Regional variation in short distance homogamy

OpenAIRE

Haandrikman, Karen; van Wissen, Leo

2011-01-01

A third of all Dutch cohabiters choose a partner from the same municipality, so-called short distance homogamy. This article analyses the regional variation in this phenomenon, and it explains this variation in terms of geographical, socioeconomic, demographic and cultural determinants. Population register data on all new cohabiters in 2004 were used. Regression methods were employed to explain spatial patterns. Regional variation in short distance homogamy is largely explained by geographica...

Hybrid Iterative Scheme for Triple Hierarchical Variational Inequalities with Mixed Equilibrium, Variational Inclusion, and Minimization Constraints

Directory of Open Access Journals (Sweden)

Lu-Chuan Ceng

2014-01-01

Full Text Available We introduce and analyze a hybrid iterative algorithm by combining Korpelevich's extragradient method, the hybrid steepest-descent method, and the averaged mapping approach to the gradient-projection algorithm. It is proven that, under appropriate assumptions, the proposed algorithm converges strongly to a common element of the fixed point set of finitely many nonexpansive mappings, the solution set of a generalized mixed equilibrium problem (GMEP, the solution set of finitely many variational inclusions, and the solution set of a convex minimization problem (CMP, which is also a unique solution of a triple hierarchical variational inequality (THVI in a real Hilbert space. In addition, we also consider the application of the proposed algorithm to solving a hierarchical variational inequality problem with constraints of the GMEP, the CMP, and finitely many variational inclusions.

The nonholonomic variational principle

Energy Technology Data Exchange (ETDEWEB)

Krupkova, Olga [Department of Algebra and Geometry, Faculty of Science, Palacky University, Tomkova 40, 779 00 Olomouc (Czech Republic); Department of Mathematics, La Trobe University, Bundoora, Victoria 3086 (Australia)], E-mail: krupkova@inf.upol.cz

2009-05-08

A variational principle for mechanical systems and fields subject to nonholonomic constraints is found, providing Chetaev-reduced equations as equations for extremals. Investigating nonholonomic variations of the Chetaev type and their properties, we develop foundations of the calculus of variations on constraint manifolds, modelled as fibred submanifolds in jet bundles. This setting is appropriate to study general first-order 'nonlinear nonitegrable constraints' that locally are given by a system of first-order ordinary or partial differential equations. We obtain an invariant constrained first variation formula and constrained Euler-Lagrange equations both in intrinsic and coordinate forms, and show that the equations are the same as Chetaev equations 'without Lagrange multipliers', introduced recently by other methods. We pay attention to two possible settings: first, when the constrained system arises from an unconstrained Lagrangian system defined in a neighbourhood of the constraint, and second, more generally, when an 'internal' constrained system on the constraint manifold is given. In the latter case a corresponding unconstrained system need not be a Lagrangian, nor even exist. We also study in detail an important particular case: nonholonomic constraints that can be alternatively modelled by means of (co)distributions in the total space of the fibred manifold; in nonholonomic mechanics this happens whenever constraints affine in velocities are considered. It becomes clear that (and why) if the distribution is completely integrable (= the constraints are semiholonomic), the principle of virtual displacements holds and can be used to obtain the constrained first variational formula by a more or less standard procedure, traditionally used when unconstrained or holonomic systems are concerned. If, however, the constraint is nonintegrable, no significant simplifications are available. Among others, some properties of nonholonomic

Diurnal variations of Titan

Science.gov (United States)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

2009-04-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

Variational principles for nonpotential operators

CERN Document Server

Filippov, V M

1989-01-01

This book develops a variational method for solving linear equations with B-symmetric and B-positive operators and generalizes the method to nonlinear equations with nonpotential operators. The author carries out a constructive extension of the variational method to "nonvariational" equations (including parabolic equations) in classes of functionals which differ from the Euler-Lagrange functionals. In this connection, some new functions spaces are considered. Intended for mathematicians working in the areas of functional analysis and differential equations, this book would also prove useful for researchers in other areas and students in advanced courses who use variational methods in solving linear and nonlinear boundary value problems in continuum mechanics and theoretical physics.

Fast Variations In Spectrum of Comet Halley

Science.gov (United States)

Borysenko, S. A.

The goal of this work is to research fast variations of spectral lines intensities in spectra of comet Halley. The present research was made on the basis of more then 500 high- resolution spectrogram obtained by L.M. Shulman and H.K. Nazarchuk in November- December, 1985 at the 6-m telescope (SAO, Russia). Some fast variations with different quasiperiods were detected in all the spectrograms. Quasiperiods of these variations were from 15 - 40 min to 1.5 - 2 hours. As data from spacecraft "Vega-2" show, more fast variations with quasiperiods 5 - 10 min are obviously present in cometary time variations. Only the most important lines so as C2, C3, CN, CH and NH2 were analyzed. False periods were checked by comparison of the power spectra of the variations with the computed spectral window of the data. Only false periods about 400 sec (the avarage period of exposition) were detected. An algorithm for analysis of locally Poisson's time series was proposed. Two types of fast variations are detected: 1)high amplitude variations with more long quasiperiods (1.5 - 2 hours) and the coefficient of crosscorrelations between line intensities about 0.9 - 0.95; 2)low amplitude variations with short periods (15 - 40 min), which look like white noise and have the coefficient of crosscorrelations about 0.1 - 0.3. This difference may be caused by nature of variations. The first type variations may be an effect of both active processes in cometary nucleus and streams of solar protons. Analysis of solar proton flux variation with energies >1 MeV in November - Decem- ber 1985 confirms the above-mentioned version. In the second case it may by only inner processes in the nucleus that generate the observed variations. For determination of general parameters of cometary atmosphere, such as the produc- tion rates of radicals C2, C3, CN, CH, and NH2 it was necessary to estimate the contri- bution of dust grains luminiscence into the continuum of the comet. Space and wave- length distribution

Importance of Local Structural Variations on Recrystallization

DEFF Research Database (Denmark)

Juul Jensen, Dorte; Lin, Fengxiang; Zhang, Yubin

2013-01-01

Effects of local variations in the deformation microstructure on subsequent recrystallization are discussed and illustrated by three examples. The three examples consider local variations on different length scales and are: 1. Effects of local variations in the deformation microstructure on the f...

Procedural facade variations from a single layout

KAUST Repository

Bao, Fan

2013-02-19

We introduce a framework to generate many variations of a facade design that look similar to a given facade layout. Starting from an input image, the facade is hierarchically segmented and labeled with a collection of manual and automatic tools. The user can then model constraints that should be maintained in any variation of the input facade design. Subsequently, facade variations are generated for different facade sizes, where multiple variations can be produced for a certain size. Computing such new facade variations has many unique challenges, and we propose a new algorithm based on interleaving heuristic search and quadratic programming. In contrast to most previous work, we focus on the generation of new design variations and not on the automatic analysis of the input\\'s structure. Adding a modeling step with the user in the loop ensures that our results routinely are of high quality. © 2013 ACM.

Procedural facade variations from a single layout

KAUST Repository

Bao, Fan; Schwarz, Michael; Wonka, Peter

2013-01-01

We introduce a framework to generate many variations of a facade design that look similar to a given facade layout. Starting from an input image, the facade is hierarchically segmented and labeled with a collection of manual and automatic tools. The user can then model constraints that should be maintained in any variation of the input facade design. Subsequently, facade variations are generated for different facade sizes, where multiple variations can be produced for a certain size. Computing such new facade variations has many unique challenges, and we propose a new algorithm based on interleaving heuristic search and quadratic programming. In contrast to most previous work, we focus on the generation of new design variations and not on the automatic analysis of the input's structure. Adding a modeling step with the user in the loop ensures that our results routinely are of high quality. © 2013 ACM.

Understanding human DNA sequence variation.

Science.gov (United States)

Kidd, K K; Pakstis, A J; Speed, W C; Kidd, J R

2004-01-01

Over the past century researchers have identified normal genetic variation and studied that variation in diverse human populations to determine the amounts and distributions of that variation. That information is being used to develop an understanding of the demographic histories of the different populations and the species as a whole, among other studies. With the advent of DNA-based markers in the last quarter century, these studies have accelerated. One of the challenges for the next century is to understand that variation. One component of that understanding will be population genetics. We present here examples of many of the ways these new data can be analyzed from a population perspective using results from our laboratory on multiple individual DNA-based polymorphisms, many clustered in haplotypes, studied in multiple populations representing all major geographic regions of the world. These data support an "out of Africa" hypothesis for human dispersal around the world and begin to refine the understanding of population structures and genetic relationships. We are also developing baseline information against which we can compare findings at different loci to aid in the identification of loci subject, now and in the past, to selection (directional or balancing). We do not yet have a comprehensive understanding of the extensive variation in the human genome, but some of that understanding is coming from population genetics.

Genetic variation in California oaks

Science.gov (United States)

Constance I. Millar; Diane L. Delany; Lawrence A. Riggs

1990-01-01

In forestry the importance of genetic variation for successful reproduction, survival and growth has been widely documented for commercial conifers; until recently, little genetic work has been done on the California oaks. Even before the nature of genetic variation was scientifically investigated, its importance was suspected in operational forestry. Many failures of...

Canonical variate regression.

Science.gov (United States)

Luo, Chongliang; Liu, Jin; Dey, Dipak K; Chen, Kun

2016-07-01

In many fields, multi-view datasets, measuring multiple distinct but interrelated sets of characteristics on the same set of subjects, together with data on certain outcomes or phenotypes, are routinely collected. The objective in such a problem is often two-fold: both to explore the association structures of multiple sets of measurements and to develop a parsimonious model for predicting the future outcomes. We study a unified canonical variate regression framework to tackle the two problems simultaneously. The proposed criterion integrates multiple canonical correlation analysis with predictive modeling, balancing between the association strength of the canonical variates and their joint predictive power on the outcomes. Moreover, the proposed criterion seeks multiple sets of canonical variates simultaneously to enable the examination of their joint effects on the outcomes, and is able to handle multivariate and non-Gaussian outcomes. An efficient algorithm based on variable splitting and Lagrangian multipliers is proposed. Simulation studies show the superior performance of the proposed approach. We demonstrate the effectiveness of the proposed approach in an [Formula: see text] intercross mice study and an alcohol dependence study. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Homogenization of variational inequalities for obstacle problems

International Nuclear Information System (INIS)

Sandrakov, G V

2005-01-01

Results on the convergence of solutions of variational inequalities for obstacle problems are proved. The variational inequalities are defined by a non-linear monotone operator of the second order with periodic rapidly oscillating coefficients and a sequence of functions characterizing the obstacles. Two-scale and macroscale (homogenized) limiting variational inequalities are obtained. Derivation methods for such inequalities are presented. Connections between the limiting variational inequalities and two-scale and macroscale minimization problems are established in the case of potential operators.

Variational integrators in plasma physics

Energy Technology Data Exchange (ETDEWEB)

Kraus, Michael

2013-07-01

To a large extent, research in plasma physics is concerned with the description and analysis of energy and momentum transfer between different scales and different kinds of waves. In the numerical modelling of such phenomena it appears to be crucial to describe the transfer processes preserving the underlying conservation laws in order to prevent physically spurious solutions. In this work, special numerical methods, so called variational integrators, are developed for several models of plasma physics. Special attention is given to conservation properties like conservation of energy and momentum. By design, variational integrators are applicable to all systems that have a Lagrangian formulation. Usually, equations of motion are derived by Hamilton's action principle and then discretised. In the application of the variational integrator theory, the order of these steps is reversed. At first, the Lagrangian and the accompanying variational principle are discretised, such that discrete equations of motion can be obtained directly by applying the discrete variational principle to the discrete Lagrangian. The advantage of this approach is that the resulting discretisation automatically retains the conservation properties of the continuous system. Following an overview of the geometric formulation of classical mechanics and field theory, which forms the basis of the variational integrator theory, variational integrators are introduced in a framework adapted to problems from plasma physics. The applicability of variational integrators is explored for several important models of plasma physics: particle dynamics (guiding centre dynamics), kinetic theory (the Vlasov-Poisson system) and fluid theory (magnetohydrodynamics). These systems, with the exception of guiding centre dynamics, do not possess a Lagrangian formulation to which the variational integrator methodology is directly applicable. Therefore the theory is extended by linking it to Ibragimov's theory of

From genomic variation to personalized medicine

DEFF Research Database (Denmark)

Wesolowska, Agata; Schmiegelow, Kjeld

Genomic variation is the basis of interindividual differences in observable traits and disease susceptibility. Genetic studies are the driving force of personalized medicine, as many of the differences in treatment efficacy can be attributed to our genomic background. The rapid development...... a considerable amount of the phenotype variability, hence the major difficulty of interpretation lies in the complexity of molecular interactions. This PhD thesis describes the state-of-art of the functional human variation research (Chapter 1) and introduces childhood acute lymphoblastic leukaemia (ALL...... the thesis and includes some final remarks on the perspectives of genomic variation research and personalized medicine. In summary, this thesis demonstrates the feasibility of integrative analyses of genomic variations and introduces large-scale hypothesis-driven SNP exploration studies as an emerging...

Genomic Sequence Variation Markup Language (GSVML).

Science.gov (United States)

Nakaya, Jun; Kimura, Michio; Hiroi, Kaei; Ido, Keisuke; Yang, Woosung; Tanaka, Hiroshi

2010-02-01

With the aim of making good use of internationally accumulated genomic sequence variation data, which is increasing rapidly due to the explosive amount of genomic research at present, the development of an interoperable data exchange format and its international standardization are necessary. Genomic Sequence Variation Markup Language (GSVML) will focus on genomic sequence variation data and human health applications, such as gene based medicine or pharmacogenomics. We developed GSVML through eight steps, based on case analysis and domain investigations. By focusing on the design scope to human health applications and genomic sequence variation, we attempted to eliminate ambiguity and to ensure practicability. We intended to satisfy the requirements derived from the use case analysis of human-based clinical genomic applications. Based on database investigations, we attempted to minimize the redundancy of the data format, while maximizing the data covering range. We also attempted to ensure communication and interface ability with other Markup Languages, for exchange of omics data among various omics researchers or facilities. The interface ability with developing clinical standards, such as the Health Level Seven Genotype Information model, was analyzed. We developed the human health-oriented GSVML comprising variation data, direct annotation, and indirect annotation categories; the variation data category is required, while the direct and indirect annotation categories are optional. The annotation categories contain omics and clinical information, and have internal relationships. For designing, we examined 6 cases for three criteria as human health application and 15 data elements for three criteria as data formats for genomic sequence variation data exchange. The data format of five international SNP databases and six Markup Languages and the interface ability to the Health Level Seven Genotype Model in terms of 317 items were investigated. GSVML was developed as

A min-max variational principle

International Nuclear Information System (INIS)

Georgiev, P.G.

1995-11-01

In this paper a variational principle for min-max problems is proved that is of the same spirit as Deville-Godefroy-Zizler's variational principle for minimization problems. A localization theorem in which the mini-max points for the perturbed function with respect top a given ε-min-max point are localized is presented. 3 refs

Amazing variational approach to chemical reactions

OpenAIRE

Fernández, Francisco M.

2009-01-01

In this letter we analyse an amazing variational approach to chemical reactions. Our results clearly show that the variational expressions are unsuitable for the analysis of empirical data obtained from chemical reactions.

Splines and variational methods

CERN Document Server

Prenter, P M

2008-01-01

One of the clearest available introductions to variational methods, this text requires only a minimal background in calculus and linear algebra. Its self-contained treatment explains the application of theoretic notions to the kinds of physical problems that engineers regularly encounter. The text's first half concerns approximation theoretic notions, exploring the theory and computation of one- and two-dimensional polynomial and other spline functions. Later chapters examine variational methods in the solution of operator equations, focusing on boundary value problems in one and two dimension

Temporal correlation in the Goldberg variations

OpenAIRE

Chestopal, Victor

2010-01-01

An interpreter of the Goldberg Variations is almost completely deprived of such utterly important guidance as the composer's tempo markings, which are as rare in the Goldberg Variations as they are in the other works of Bach. The final goal of my study is to suggest a logical foundation, upon which an interpreter of the Goldberg Variations can make his/her choice of tempi. Upon the analysis of opus's structure, which reveals an impressive panorama of symmetries, I suggest a multilevel system ...

Variations in government contract in Malaysia

Directory of Open Access Journals (Sweden)

Jaspal Singh Nachatar

2010-12-01

Full Text Available The complexity of construction works means that it is hardly possible to complete a project without changes to the plans or the construction process itself. There can only be a minority of contracts of any size in which the subject matter when completed is identical in every respect with what was contemplated at the outset. As such, variations are inevitable in even the best-planned contracts. This study is attempted to examine the ways a variation was formed in law and project, in finding out whether the Standard Form of Contract used in Malaysia particularly the government Public Works Department (PWD form has been utilized to the best level in variation cases. Additionally, this study examined the benefits of variations to parties in contract and also provides suggestions and assumptions in an effort to contribute solutions to issues and problem detected. The research methodology used in this study was an extensive review of relevant literature, case study, empirical questionnaires and structured interviews and general observations based on experience and surroundings. The academic study approach incorporated stages such as initial understanding, data and information gathering, analysis of data, findings and conclusion and general suggestions in the study. The major findings of this study, among others, revealed that the existences of variations are common in projects. The main cause of variations was due to client request because of inadequate project objectives for the designer to develop comprehensive design. Besides, the analysis pointed out that the government form of contract the Public Works Department (PWD 203/203A can help in overcoming projects with variation because of the clear defined procedure. This study also found that proper planning and coordination at tender stage can minimize the risk of ‘unwanted’ variations. In conclusion, this study recommended that future research should be done in design and build based contract

Blood lipid measurements. Variations and practical utility.

Science.gov (United States)

Cooper, G R; Myers, G L; Smith, S J; Schlant, R C

1992-03-25

To describe the magnitude and impact of the major biological and analytical sources of variation in serum lipid and lipoprotein levels on risk of coronary heart disease; to present a way to qualitatively estimate the total intraindividual variation; and to demonstrate how to determine the number of specimens required to estimate, with 95% confidence, the "true" underlying total cholesterol value in the serum of a patient. Representative references on each source of variation were selected from more than 300 reviewed publications, most published within the past 5 years, to document current findings and concepts. Most articles reviewed were in English. Studies on biological sources of variation were selected using the following criteria: representative of published findings, clear statement of either significant or insignificant results, and acquisition of clinical and laboratory data under standardized conditions. Representative results for special populations such as women and children are reported when results differ from those of adult men. References were selected based on acceptable experimental design and use of standardized laboratory lipid measurements. The lipid levels considered representative for a selected source of variation arose from quantitative measurements by a suitably standardized laboratory. Statistical analysis of data was examined to assure reliability. The proposed method of estimating the biological coefficient of variation must be considered to give qualitative results, because only two or three serial specimens are collected in most cases for the estimation. Concern has arisen about the magnitude, impact, and interpretation of preanalytical as well as analytical sources of variation on reported results of lipid measurements of an individual. Preanalytical sources of variation from behavioral, clinical, and sampling sources constitute about 60% of the total variation in a reported lipid measurement of an individual. A technique is presented

A Brief Study of Variation Theory in Quality Management

Directory of Open Access Journals (Sweden)

Mostafa Farah Bakhsh

2016-06-01

Full Text Available Variation is part of everyday life and exists all the time. Variation is the product of differences. Difference in nature of processes results in different products during the time. Proper diagnosis of variation patterns in minimizing the loss is necessary. Continuous quality improvement is regarded as successive reduction of performance variation for delivering high quality products to the customers. In Deming viewpoint, quality deviation is classified to two groups of common and special causes. Variation is not a new word, but understanding and concerns about it are modern. First step in performance variation management is acceptance and belief of variation. For proper management of variations, appropriate tools should be used for detection and display of them. Control are useful tools in recognition, analysis and removing process performance variations.

Variation of Parameters in Differential Equations (A Variation in Making Sense of Variation of Parameters)

Science.gov (United States)

Quinn, Terry; Rai, Sanjay

2012-01-01

The method of variation of parameters can be found in most undergraduate textbooks on differential equations. The method leads to solutions of the non-homogeneous equation of the form y = u[subscript 1]y[subscript 1] + u[subscript 2]y[subscript 2], a sum of function products using solutions to the homogeneous equation y[subscript 1] and…

Difference Discrete Variational Principles, Euler-Lagrange Cohomology and Symplectic, Multisymplectic Structures I: Difference Discrete Variational Principle

Institute of Scientific and Technical Information of China (English)

GUO Han-Ying,; LI Yu-Qi; WU Ke1; WANG Shi-Kun

2002-01-01

In this first paper of a series, we study the difference discrete variational principle in the framework of multi-parameter differential approach by regarding the forward difference as an entire geometric object in view of noncommutative differential geometry. Regarding the difference as an entire geometric object, the difference discrete version of Legendre transformation can be introduced. By virtue of this variational principle, we can discretely deal with the variation problems in both the Lagrangian and Hamiltonian formalisms to get difference discrete Euler-Lagrange equations and canonical ones for the difference discrete versions of the classical mechanics and classical field theory.

Strongly nonlinear parabolic variational inequalities.

Science.gov (United States)

Browder, F E; Brézis, H

1980-02-01

An existence and uniqueness result is established for a general class of variational inequalities for parabolic partial differential equations of the form partial differentialu/ partial differentialt + A(u) + g(u) = f with g nondecreasing but satisfying no growth condition. The proof is based upon a type of compactness result for solutions of variational inequalities that should find a variety of other applications.

Sex reduces genetic variation: a multidisciplinary review.

Science.gov (United States)

Gorelick, Root; Heng, Henry H Q

2011-04-01

For over a century, the paradigm has been that sex invariably increases genetic variation, despite many renowned biologists asserting that sex decreases most genetic variation. Sex is usually perceived as the source of additive genetic variance that drives eukaryotic evolution vis-à-vis adaptation and Fisher's fundamental theorem. However, evidence for sex decreasing genetic variation appears in ecology, paleontology, population genetics, and cancer biology. The common thread among many of these disciplines is that sex acts like a coarse filter, weeding out major changes, such as chromosomal rearrangements (that are almost always deleterious), but letting minor variation, such as changes at the nucleotide or gene level (that are often neutral), flow through the sexual sieve. Sex acts as a constraint on genomic and epigenetic variation, thereby limiting adaptive evolution. The diverse reasons for sex reducing genetic variation (especially at the genome level) and slowing down evolution may provide a sufficient benefit to offset the famed costs of sex. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

Luminosity Variations in Post-AGB Stars

Science.gov (United States)

Mesler, Robert; Henson, G.

2007-12-01

Although much is known about AGB stars and planetary nebulae, relatively little is known about the phase of a star's life in which it transitions between those two states. We have measured the variations in luminosity of a sample of known Post-AGB stars (as well as several candidates) relative to nearby, non-variable stars in order to compare them with theoretical models. The typical behavior of the observed variations is described and an attempt is made to discern whether any periodicity might be present. Luminosity variations were found to be on the order of a few hundredths to a few tenths of a magnitude for the stars that were surveyed, with occasional fluctuations of up to a magnitude. This agrees with current models of Post-AGB stars. Each star fell into one of three categories, which were termed groups 1, 2, and 3. Group 1 stars showed long term, non-periodic luminosity variations on the scale of weeks or longer and were most likely to display some sort of short term, coherent luminosity oscillation (each of which lasted for only a few cycles). Group 2 stars showed erratic, short-term magnitude variations occurring on scales of several days. Group 3 stars showed little or no variation in magnitude. Of the 27 Post-AGB stars that were sampled, five fell into group 1, fifteen fell into group 2, and seven fell into group 3. The luminosity variations tended to be color-independent, and occurred on timescales ranging nearly continuously from a few days to more than a year. No clear periodic behavior was found in any star in our sample. This project was funded by a partnership between the National Science Foundation (NSF AST-0552798), Research Experiences for Undergraduates (REU), and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs.

Exploring subdomain variation in biomedical language

Directory of Open Access Journals (Sweden)

Séaghdha Diarmuid Ó

2011-05-01

Full Text Available Abstract Background Applications of Natural Language Processing (NLP technology to biomedical texts have generated significant interest in recent years. In this paper we identify and investigate the phenomenon of linguistic subdomain variation within the biomedical domain, i.e., the extent to which different subject areas of biomedicine are characterised by different linguistic behaviour. While variation at a coarser domain level such as between newswire and biomedical text is well-studied and known to affect the portability of NLP systems, we are the first to conduct an extensive investigation into more fine-grained levels of variation. Results Using the large OpenPMC text corpus, which spans the many subdomains of biomedicine, we investigate variation across a number of lexical, syntactic, semantic and discourse-related dimensions. These dimensions are chosen for their relevance to the performance of NLP systems. We use clustering techniques to analyse commonalities and distinctions among the subdomains. Conclusions We find that while patterns of inter-subdomain variation differ somewhat from one feature set to another, robust clusters can be identified that correspond to intuitive distinctions such as that between clinical and laboratory subjects. In particular, subdomains relating to genetics and molecular biology, which are the most common sources of material for training and evaluating biomedical NLP tools, are not representative of all biomedical subdomains. We conclude that an awareness of subdomain variation is important when considering the practical use of language processing applications by biomedical researchers.

Population genetic variation in gene expression is associated withphenotypic variation in Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Fay, Justin C.; McCullough, Heather L.; Sniegowski, Paul D.; Eisen, Michael B.

2004-02-25

The relationship between genetic variation in gene expression and phenotypic variation observable in nature is not well understood. Identifying how many phenotypes are associated with differences in gene expression and how many gene-expression differences are associated with a phenotype is important to understanding the molecular basis and evolution of complex traits. Results: We compared levels of gene expression among nine natural isolates of Saccharomyces cerevisiae grown either in the presence or absence of copper sulfate. Of the nine strains, two show a reduced growth rate and two others are rust colored in the presence of copper sulfate. We identified 633 genes that show significant differences in expression among strains. Of these genes,20 were correlated with resistance to copper sulfate and 24 were correlated with rust coloration. The function of these genes in combination with their expression pattern suggests the presence of both correlative and causative expression differences. But the majority of differentially expressed genes were not correlated with either phenotype and showed the same expression pattern both in the presence and absence of copper sulfate. To determine whether these expression differences may contribute to phenotypic variation under other environmental conditions, we examined one phenotype, freeze tolerance, predicted by the differential expression of the aquaporin gene AQY2. We found freeze tolerance is associated with the expression of AQY2. Conclusions: Gene expression differences provide substantial insight into the molecular basis of naturally occurring traits and can be used to predict environment dependent phenotypic variation.

In vitro plant regeneration of Spartina argentinensis Parodi

Directory of Open Access Journals (Sweden)

Mirian Susana Bueno

2012-07-01

; in vitro; organogénesis; variación somaclonal. Abstract: Spartina argentinensis Parodi is the dominant species of the temporally-flooded halophyte communities of the Santa Fe Province, Argentina. It occupies around 20,000 km2 and it is mainly used as low-cost impute forage for cattle production. The objective of this work was to develop a simple method for in vitro plant regeneration of S. argentinensis that could be used for fundamental and applied research. Leaf-basal segments from both young and mature plants, roots tips and immature inflorescences were used as explants. Culture media for calli, shoot, and root induction consisted of Murashige & Skoog salts supplemented with different plant growth regulators (2,4-D; BAP or ANA. Most of the explants (with the exception of root tips showed cell proliferation and calli formation after 30 days of culture. However, only immature inflorescences responded to shoot and root induction when calli were incubated on MS salts plus 2,4_D and BAP (0.1 and 0.01 mg.L-1, respectively, transferred to shoot inductionmedia (MS salts plus BAP, 0.5 mg.L-1 and then to root induction media (MS slts plus NAA 0.5 mg.L-1. Regenerated plants were evaluated for morphological abnormalities and lignin content. Historical analysis of regenerating calli showed that shoots and roots originated via organogenesis. A low proportion of regenerated plants resulted with deficiency in chlorophyll (albino plants and other morphological abnormalities. Interestingly, significant variations in the lignin content were detected between regenerated plants. The protocol described in this work could be used ordinarily for S. argentinensis in vitro plant regeneration and selecting somaclonal variants for breeding purposes. Key words: Spartina argentinensis; in vitro; organogenesis; somaclonal variation.

A variational approach to niche construction.

Science.gov (United States)

Constant, Axel; Ramstead, Maxwell J D; Veissière, Samuel P L; Campbell, John O; Friston, Karl J

2018-04-01

In evolutionary biology, niche construction is sometimes described as a genuine evolutionary process whereby organisms, through their activities and regulatory mechanisms, modify their environment such as to steer their own evolutionary trajectory, and that of other species. There is ongoing debate, however, on the extent to which niche construction ought to be considered a bona fide evolutionary force, on a par with natural selection. Recent formulations of the variational free-energy principle as applied to the life sciences describe the properties of living systems, and their selection in evolution, in terms of variational inference. We argue that niche construction can be described using a variational approach. We propose new arguments to support the niche construction perspective, and to extend the variational approach to niche construction to current perspectives in various scientific fields. © 2018 The Authors.

The circadian variation of premature atrial contractions

DEFF Research Database (Denmark)

Larsen, Bjørn Strøier; Kumarathurai, Preman; Nielsen, Olav W

2016-01-01

AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF...... variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than...

Solar cycle variations in IMF intensity

International Nuclear Information System (INIS)

King, J.H.

1979-01-01

Annual averages of logarithms of hourly interplanetary magnetic field (IMF) intensities, obtained from geocentric spacecraft between November 1963 and December 1977, reveal the following solar cycle variation. For 2--3 years at each solar minimum period, the IMF intensity is depressed by 10--15% relative to its mean value realized during a broad 9-year period contered at solar maximum. No systematic variations occur during this 9-year period. The solar minimum decrease, although small in relation to variations in some other solar wind parameters, is both statistically and physically significant

Variational form for a viscous plasma

International Nuclear Information System (INIS)

Ishida, A.; Steinhauer, L.C.; Berk, H.L.

1991-01-01

The variational formulation for a fluid plasma including the parallel and gyroviscosities is developed using the basic approach of Berk et al. [Phys. Fluids 24, 2245 (1981)]. The equivalence of the variational problem to the original viscous fluid equations of motion is shown. The theory is developed for an axisymmetric plasma with no magnetic field in the azimuthal direction and therefore applies to field-reversed configurations and axisymmetric mirrors. This theory offers the advantage of describing both parallel and transverse ion kinetic effects within the simplicity afforded by a variational fluid model

Variational theory of nuclear and neutron matter

International Nuclear Information System (INIS)

Pandharipande, V.R.; Wiringa, R.B.

1989-06-01

In these lectures we will discuss attempts to solve the A = 3 to ∞ nuclear many-body problems with the variational method. We choose the form of a variational wave function Χ v (1, 2 hor-ellipsis A) to describe the ground state. The Χ v and the ground-state energy E v are obtained by minimizing E v = left-angle Χ v |H|Χ v right-angle/left-angle Χ v |Χ v right-angle with respect to variations in Χ v . If the form of the variational wave function is chosen properly we can expect Χ v ∼ Χ 0 and E v ∼ E 0 where Χ 0 and E 0 are the exact ground-state wave function and energy. In general E v ≥ E 0 in variational calculations. 63 refs., 11 figs

Variational principles of continuum mechanics. Vol. 1. Fundamentals

Energy Technology Data Exchange (ETDEWEB)

Berdichevsky, Victor L. [Wayne State Univ., Detroit, MI (United States). Dept. of Mechanical Engineering

2009-07-01

The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems. Berdichevsky's work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given. In this book, the first volume, the author covers the variational principles for systems with a finite number of degrees of freedom; the variational principles of thermodynamics; the basics of continuum mechanics; the variational principles for classical models of continuum mechanics, such as elastic and plastic bodies, and ideal and viscous fluids; and direct methods of calculus of variations. (orig.)

Genetic variation in social influence on mate preferences

Science.gov (United States)

Rebar, Darren; Rodríguez, Rafael L.

2013-01-01

Patterns of phenotypic variation arise in part from plasticity owing to social interactions, and these patterns contribute, in turn, to the form of selection that shapes the variation we observe in natural populations. This proximate–ultimate dynamic brings genetic variation in social environments to the forefront of evolutionary theory. However, the extent of this variation remains largely unknown. Here, we use a member of the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae) to assess how mate preferences are influenced by genetic variation in the social environment. We used full-sibling split-families as ‘treatment’ social environments, and reared focal females alongside each treatment family, describing the mate preferences of the focal females. With this method, we detected substantial genetic variation in social influence on mate preferences. The mate preferences of focal females varied according to the treatment families along with which they grew up. We discuss the evolutionary implications of the presence of such genetic variation in social influence on mate preferences, including potential contributions to the maintenance of genetic variation, the promotion of divergence, and the adaptive evolution of social effects on fitness-related traits. PMID:23698010

Variation principle for nonlinear wave propagation

International Nuclear Information System (INIS)

Watanabe, T.; Lee, Y.C.; Nishikawa, Kyoji; Hojo, H.; Yoshida, Y.

1976-01-01

Variation principle is derived which determines stationary nonlinear propagation of electrostatic waves in the self-consistent density profile. Example is given for lower-hybrid waves and the relation to the variation principle for the Lagrangian density of electromagnetic fluids is discussed

Outdoor radon variation in Romania

International Nuclear Information System (INIS)

Simion, Elena; Simion, Florin

2008-01-01

Full text: The results of a long-term survey (1992 - 2006) of the variations of outdoor radon concentrations in semi-natural location from Romania are reported in the present paper. Measurements, covering between two and four sessions of the day (morning, afternoon, evening and night), were performed on a daily bases by 37 Environmental Radioactivity Monitoring Stations from National Environmental Radioactivity Survey Network. The method used was based on indirect determination of outdoor radon from aerosol samples collected on glass micro-fibre filters by drawing the air through the filters. The sampling was performed in a fixed place at a height of 2 m above the ground surface. Total beta counting of aerosol samples collected was performed immediately and after 20 hours. Values recorded during the years of continuous measurement indicated the presence of several patterns in the long-term variation of outdoor radon concentration: diurnal, seasonal and annual variation. For diurnal variation, outdoor radon concentration shows a maximum values in the night (early hours) and minimum values by day (in the afternoon). On average, this maximum is a factor of 2 higher than the minimum. Late autumn - beginning of winter maximum and an early spring minimum are characteristic for seasonal patterns. In the long term a seasonal pattern was observed for diurnal variation, with an average diurnal maximum to minimum ratio of 1.33 in winter compared with 3.0 in the summer months. The variations of outdoor radon levels showed little correlation with the uranium concentration of the ground and were attributed to changes in soil moisture content. In dry seasons, because of the low precipitation, the soil was drying out in the summer allowing fractures to develop and radon to migrate easily through the ground. Depending on micro-climatic and geological conditions, outdoor radon average concentrations in different regions of Romania are from 1200 mBq/mc to 13065 mBq/mc. The smallest

Y-Chromosome variation in hominids: intraspecific variation is limited to the polygamous chimpanzee.

Directory of Open Access Journals (Sweden)

Gabriele Greve

Full Text Available BACKGROUND: We have previously demonstrated that the Y-specific ampliconic fertility genes DAZ (deleted in azoospermia and CDY (chromodomain protein Y varied with respect to copy number and position among chimpanzees (Pan troglodytes. In comparison, seven Y-chromosomal lineages of the bonobo (Pan paniscus, the chimpanzee's closest living relative, showed no variation. We extend our earlier comparative investigation to include an analysis of the intraspecific variation of these genes in gorillas (Gorilla gorilla and orangutans (Pongo pygmaeus, and examine the resulting patterns in the light of the species' markedly different social and mating behaviors. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence in situ hybridization analysis (FISH of DAZ and CDY in 12 Y-chromosomal lineages of western lowland gorilla (G. gorilla gorilla and a single lineage of the eastern lowland gorilla (G. beringei graueri showed no variation among lineages. Similar findings were noted for the 10 Y-chromosomal lineages examined in the Bornean orangutan (Pongo pygmaeus, and 11 Y-chromosomal lineages of the Sumatran orangutan (P. abelii. We validated the contrasting DAZ and CDY patterns using quantitative real-time polymerase chain reaction (qPCR in chimpanzee and bonobo. CONCLUSION/SIGNIFICANCE: High intraspecific variation in copy number and position of the DAZ and CDY genes is seen only in the chimpanzee. We hypothesize that this is best explained by sperm competition that results in the variant DAZ and CDY haplotypes detected in this species. In contrast, bonobos, gorillas and orangutans-species that are not subject to sperm competition-showed no intraspecific variation in DAZ and CDY suggesting that monoandry in gorillas, and preferential female mate choice in bonobos and orangutans, probably permitted the fixation of a single Y variant in each taxon. These data support the notion that the evolutionary history of a primate Y chromosome is not simply encrypted in its DNA

Variational principle for nonlinear gyrokinetic Vlasov--Maxwell equations

International Nuclear Information System (INIS)

Brizard, Alain J.

2000-01-01

A new variational principle for the nonlinear gyrokinetic Vlasov--Maxwell equations is presented. This Eulerian variational principle uses constrained variations for the gyrocenter Vlasov distribution in eight-dimensional extended phase space and turns out to be simpler than the Lagrangian variational principle recently presented by H. Sugama [Phys. Plasmas 7, 466 (2000)]. A local energy conservation law is then derived explicitly by the Noether method. In future work, this new variational principle will be used to derive self-consistent, nonlinear, low-frequency Vlasov--Maxwell bounce-gyrokinetic equations, in which the fast gyromotion and bounce-motion time scales have been eliminated

Decomposing Firm-level Sales Variation

DEFF Research Database (Denmark)

Munch, Jakob Roland; Nguyen, Daniel Xuyen

, and that for the median product it drives 31% of the sales variation. When we remove first-time exports from our sample, the median value increases to 40%, implying that firm-destination-specific effects are most important the first year. We conclude that while firm-specific productivity can account for some......We measure the contribution of firm-specific effects to overall sales variation within a destination and find it remarkably low. Our empirical decomposition is structurally motivated by a heterogeneity model of exporting involving destination-specific, firm-specific, and firm......-destination-specific latent effects with incidental truncation. We use a highly detailed dataset with exports by products and destinations for all Danish manufacturing fi…rms. We fi…nd the contribution of firm-specific heterogeneity to within-destination sales variation varies greatly across HS6 products...

Variational methods in molecular modeling

CERN Document Server

2017-01-01

This book presents tutorial overviews for many applications of variational methods to molecular modeling. Topics discussed include the Gibbs-Bogoliubov-Feynman variational principle, square-gradient models, classical density functional theories, self-consistent-field theories, phase-field methods, Ginzburg-Landau and Helfrich-type phenomenological models, dynamical density functional theory, and variational Monte Carlo methods. Illustrative examples are given to facilitate understanding of the basic concepts and quantitative prediction of the properties and rich behavior of diverse many-body systems ranging from inhomogeneous fluids, electrolytes and ionic liquids in micropores, colloidal dispersions, liquid crystals, polymer blends, lipid membranes, microemulsions, magnetic materials and high-temperature superconductors. All chapters are written by leading experts in the field and illustrated with tutorial examples for their practical applications to specific subjects. With emphasis placed on physical unders...

Variations in the origin of inferior phrenic arteries and their relationship to celiac axis variations on CT angiography

Energy Technology Data Exchange (ETDEWEB)

Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal [Dept. of Radiology, Tepecik Training and Research Hospital, Izmir (Turkmenistan); Toka, Onur [Dept. of Statistics, Hacettepe University, Ankara (Turkmenistan)

2017-04-15

Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18–94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation.

Variations in the origin of inferior phrenic arteries and their relationship to celiac axis variations on CT angiography

International Nuclear Information System (INIS)

Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal; Toka, Onur

2017-01-01

Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18–94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation

Variations in the Origin of Inferior Phrenic Arteries and Their Relationship to Celiac Axis Variations on CT Angiography.

Science.gov (United States)

Aslaner, Ramazan; Pekcevik, Yeliz; Sahin, Hilal; Toka, Onur

2017-01-01

Knowing the origin of the inferior phrenic artery (IPA) is important prior to surgical interventions and interventional radiological procedures related to IPA. We aimed to identify variations in the origin of IPA and to investigate the relationship between the origin of IPA and celiac axis variations using computed tomography angiography (CTA). The CTA images of 1000 patients (737 male and 263 female, the mean age 60, range 18-94 years) were reviewed in an analysis of IPA and celiac axis variations. The origin of IPA was divided into two groups, those originating as a common trunk and those originating independently without a truncus. The relationship between the origin of IPA and celiac axis variation was analyzed using Pearson's chi-square test. Both IPAs originated from a common trunk in 295 (29.5%) patients. From which the majority of the common trunk originated from the aorta. Contrastingly, the inferior phrenic arteries originated from different origins in 705 (70.5%) patients. The majority of the right inferior phrenic artery (RIPA) and the left inferior phrenic artery (LIPA) originated independently from the celiac axis. Variation in the celiac axis were detected in 110 (11%) patients. The origin of IPA was found to be significantly different in the presence of celiac axis variation. The majority of IPA originated from the aorta in patients with a common IPA trunk, while the majority of RIPA and LIPA originating from the celiac axis in patients without a common IPA trunk. Thus, the origin of IPA may widely differ in the presence of celiac axis variation.

Regional variation in short distance homogamy

NARCIS (Netherlands)

Haandrikman, K.; van Wissen, L.J.G.

2011-01-01

A third of all Dutch cohabiters choose a partner from the same municipality, so-called short distance homogamy. This article analyses the regional variation in this phenomenon, and it explains this variation in terms of geographical, socioeconomic, demographic and cultural determinants. Population

Variation-aware advanced CMOS devices and SRAM

CERN Document Server

Shin, Changhwan

2016-01-01

This book provides a comprehensive overview of contemporary issues in complementary metal-oxide semiconductor (CMOS) device design, describing how to overcome process-induced random variations such as line-edge-roughness, random-dopant-fluctuation, and work-function variation, and the applications of novel CMOS devices to cache memory (or Static Random Access Memory, SRAM). The author places emphasis on the physical understanding of process-induced random variation as well as the introduction of novel CMOS device structures and their application to SRAM. The book outlines the technical predicament facing state-of-the-art CMOS technology development, due to the effect of ever-increasing process-induced random/intrinsic variation in transistor performance at the sub-30-nm technology nodes. Therefore, the physical understanding of process-induced random/intrinsic variations and the technical solutions to address these issues plays a key role in new CMOS technology development. This book aims to provide the reade...

Biological variation of total prostate-specific antigen

DEFF Research Database (Denmark)

Söletormos, Georg; Semjonow, Axel; Sibley, Paul E C

2005-01-01

BACKGROUND: The objectives of this study were to determine whether a single result for total prostate-specific antigen (tPSA) can be used confidently to guide the need for prostate biopsy and by how much serial tPSA measurements must differ to be significant. tPSA measurements include both...... analytical and biological components of variation. The European Group on Tumor Markers conducted a literature survey to determine both the magnitude and impact of biological variation on single, the mean of replicate, and serial tPSA measurements. METHODS: The survey yielded 27 studies addressing the topic......, and estimates for the biological variation of tPSA could be derived from 12 of these studies. RESULTS: The mean biological variation was 20% in the concentration range 0.1-20 microg/L for men over 50 years. The biological variation means that the one-sided 95% confidence interval (CI) of the dispersion...

Extensive Variation in Chromatin States Across Humans

KAUST Repository

Kasowski, M.

2013-10-17

The majority of disease-associated variants lie outside protein-coding regions, suggesting a link between variation in regulatory regions and disease predisposition. We studied differences in chromatin states using five histone modifications, cohesin, and CTCF in lymphoblastoid lines from 19 individuals of diverse ancestry. We found extensive signal variation in regulatory regions, which often switch between active and repressed states across individuals. Enhancer activity is particularly diverse among individuals, whereas gene expression remains relatively stable. Chromatin variability shows genetic inheritance in trios, correlates with genetic variation and population divergence, and is associated with disruptions of transcription factor binding motifs. Overall, our results provide insights into chromatin variation among humans.

Extensive Variation in Chromatin States Across Humans

KAUST Repository

Kasowski, M.; Kyriazopoulou-Panagiotopoulou, S.; Grubert, F.; Zaugg, J. B.; Kundaje, A.; Liu, Y.; Boyle, A. P.; Zhang, Q. C.; Zakharia, F.; Spacek, D. V.; Li, J.; Xie, D.; Olarerin-George, A.; Steinmetz, L. M.; Hogenesch, J. B.; Kellis, M.; Batzoglou, S.; Snyder, M.

2013-01-01

The majority of disease-associated variants lie outside protein-coding regions, suggesting a link between variation in regulatory regions and disease predisposition. We studied differences in chromatin states using five histone modifications, cohesin, and CTCF in lymphoblastoid lines from 19 individuals of diverse ancestry. We found extensive signal variation in regulatory regions, which often switch between active and repressed states across individuals. Enhancer activity is particularly diverse among individuals, whereas gene expression remains relatively stable. Chromatin variability shows genetic inheritance in trios, correlates with genetic variation and population divergence, and is associated with disruptions of transcription factor binding motifs. Overall, our results provide insights into chromatin variation among humans.

Factors influencing variation in dentist service rates.

Science.gov (United States)

Grembowski, D; Milgrom, P; Fiset, L

1990-01-01

In the previous article, we calculated dentist service rates for 200 general dentists based on a homogeneous, well-educated, upper-middle-class population of patients. Wide variations in the rates were detected. In this analysis, factors influencing variation in the rates were identified. Variation in rates for categories of dental services was explained by practice characteristics, patient exposure to fluoridated water supplies, and non-price competition in the dental market. Rates were greatest in large, busy practices in markets with high fees. Older practices consistently had lower rates across services. As a whole, these variables explained between 5 and 30 percent of the variation in the rates.

Seasonal variation of radon concentrations in UK homes

International Nuclear Information System (INIS)

Miles, J C H; Howarth, C B; Hunter, N

2012-01-01

The patterns of seasonal variation of radon concentrations were measured in 91 homes in five regions of the UK over a period of two years. The results showed that there was no significant difference between the regions in the pattern or magnitude of seasonal variation in radon concentrations. The arithmetic mean variation was found to be close to that found previously in the UK national survey. Differences in the pattern between the two years of the study were not significant. Two-thirds of homes in the study followed the expected pattern of high radon in the winter and low radon in the summer. Most of the rest showed little seasonal variation, and a few showed a reversed seasonal pattern. The study does not provide any clear evidence for the recorded house characteristics having an effect on the seasonal variation in radon concentrations in UK homes, though the statistical power for determining such effects is limited in this study. The magnitude of the seasonal variation varied widely between homes. Analysis of the individual results from the homes showed that because of the wide variation in the amount of seasonal variation, applying seasonal correction factors to the results of three-month measurements can yield only relatively small improvements in the accuracy of estimates of annual mean concentrations.

The ecological importance of intraspecific variation.

Science.gov (United States)

Des Roches, Simone; Post, David M; Turley, Nash E; Bailey, Joseph K; Hendry, Andrew P; Kinnison, Michael T; Schweitzer, Jennifer A; Palkovacs, Eric P

2018-01-01

Human activity is causing wild populations to experience rapid trait change and local extirpation. The resulting effects on intraspecific variation could have substantial consequences for ecological processes and ecosystem services. Although researchers have long acknowledged that variation among species influences the surrounding environment, only recently has evidence accumulated for the ecological importance of variation within species. We conducted a meta-analysis comparing the ecological effects of variation within a species (intraspecific effects) with the effects of replacement or removal of that species (species effects). We evaluated direct and indirect ecological responses, including changes in abundance (or biomass), rates of ecological processes and changes in community composition. Our results show that intraspecific effects are often comparable to, and sometimes stronger than, species effects. Species effects tend to be larger for direct ecological responses (for example, through consumption), whereas intraspecific effects and species effects tend to be similar for indirect responses (for example, through trophic cascades). Intraspecific effects are especially strong when indirect interactions alter community composition. Our results summarize data from the first generation of studies examining the relative ecological effects of intraspecific variation. Our conclusions can help inform the design of future experiments and the formulation of strategies to quantify and conserve biodiversity.

Parkinson's disease and mitochondrial gene variations

DEFF Research Database (Denmark)

Andalib, Sasan; Vafaee, Manouchehr Seyedi; Gjedde, Albert

2014-01-01

Parkinson's disease (PD) is a common disorder of the central nervous system in the elderly. The pathogenesis of PD is a complex process, with genetics as an important contributing factor. This factor may stem from mitochondrial gene variations and mutations as well as from nuclear gene variations...

Variational theory of nuclear and neutron matter

Energy Technology Data Exchange (ETDEWEB)

Pandharipande, V.R.; Wiringa, R.B. (Illinois Univ., Urbana, IL (USA). Dept. of Physics; Argonne National Lab., IL (USA))

1989-06-01

In these lectures we will discuss attempts to solve the A = 3 to {infinity} nuclear many-body problems with the variational method. We choose the form of a variational wave function {Chi}{sub v}(1, 2{hor ellipsis}A) to describe the ground state. The {Chi}{sub v} and the ground-state energy E{sub v} are obtained by minimizing E{sub v} = {l angle}{Chi}{sub v}{vert bar}H{vert bar}{Chi}{sub v}{r angle}/{l angle}{Chi}{sub v}{vert bar}{Chi}{sub v}{r angle} with respect to variations in {Chi}{sub v}. If the form of the variational wave function is chosen properly we can expect {Chi}{sub v} {approx} {Chi}{sub 0} and E{sub v} {approx} E{sub 0} where {Chi}{sub 0} and E{sub 0} are the exact ground-state wave function and energy. In general E{sub v} {ge} E{sub 0} in variational calculations. 63 refs., 11 figs.

On minimizers of causal variational principles

International Nuclear Information System (INIS)

Schiefeneder, Daniela

2011-01-01

Causal variational principles are a class of nonlinear minimization problems which arise in a formulation of relativistic quantum theory referred to as the fermionic projector approach. This thesis is devoted to a numerical and analytic study of the minimizers of a general class of causal variational principles. We begin with a numerical investigation of variational principles for the fermionic projector in discrete space-time. It is shown that for sufficiently many space-time points, the minimizing fermionic projector induces non-trivial causal relations on the space-time points. We then generalize the setting by introducing a class of causal variational principles for measures on a compact manifold. In our main result we prove under general assumptions that the support of a minimizing measure is either completely timelike, or it is singular in the sense that its interior is empty. In the examples of the circle, the sphere and certain flag manifolds, the general results are supplemented by a more detailed analysis of the minimizers. (orig.)

Regional variation in electroconvulsive therapy use.

LENUS (Irish Health Repository)

Dunne, R

2011-03-01

Although electroconvulsive therapy (ECT) is the most powerful treatment for depression, substantial variability in use has been described in Ireland. The Mental Health Commission collects usage data from approved centres but does not include home addresses or independent sector patients. Therefore, estimates of regional variation cannot be accurate, e.g. 145 (35% of total) independent sector patients were omitted from their 2008 analysis. When public and independent sector patients are combined inter-regional variation for 2008 is more than halved (chi-squared decreased from 83 to 30), with Western region contributing most to variation (chi-squared = 43). Ratio of ECT programmes to depressed admissions correlated negatively with rate for depressed admissions (r = -0.53, p = 0.01), while depressed admission numbers correlated with acute beds per area (r = 0.68, p = 0.001). Regional variation in ECT is less than previously reported; service factors probably account for much of this with smaller centres admitting severely ill patients more likely to require ECT.

Variational Algorithms for Test Particle Trajectories

Science.gov (United States)

Ellison, C. Leland; Finn, John M.; Qin, Hong; Tang, William M.

2015-11-01

The theory of variational integration provides a novel framework for constructing conservative numerical methods for magnetized test particle dynamics. The retention of conservation laws in the numerical time advance captures the correct qualitative behavior of the long time dynamics. For modeling the Lorentz force system, new variational integrators have been developed that are both symplectic and electromagnetically gauge invariant. For guiding center test particle dynamics, discretization of the phase-space action principle yields multistep variational algorithms, in general. Obtaining the desired long-term numerical fidelity requires mitigation of the multistep method's parasitic modes or applying a discretization scheme that possesses a discrete degeneracy to yield a one-step method. Dissipative effects may be modeled using Lagrange-D'Alembert variational principles. Numerical results will be presented using a new numerical platform that interfaces with popular equilibrium codes and utilizes parallel hardware to achieve reduced times to solution. This work was supported by DOE Contract DE-AC02-09CH11466.

Thematic Composition and Idiom Variation

Directory of Open Access Journals (Sweden)

Cserép Attila

2017-11-01

Full Text Available The Corpus of Contemporary American English (COCA has been studied to retrieve variant forms of semantically decomposable idioms that have no thematic composition for the purpose of determining whether thematic composition is a necessary criterion for idiom variation as claimed by Horn (2003. The syntactic variants searched for include passive, raising, tough-movement, relative clauses and wh-questions. Horn’s (2003 hypothesis is not fully confirmed, as some variation has been found.

Exploring Duopoly Markets with Conjectural Variations

Science.gov (United States)

Julien, Ludovic A.; Musy, Olivier; Saïdi, Aurélien W.

2014-01-01

In this article, the authors investigate competitive firm behaviors in a two-firm environment assuming linear cost and demand functions. By introducing conjectural variations, they capture the different market structures as specific configurations of a more general model. Conjectural variations are based on the assumption that each firm believes…

Generalized variational formulations for extended exponentially fractional integral

Directory of Open Access Journals (Sweden)

Zuo-Jun Wang

2016-01-01

Full Text Available Recently, the fractional variational principles as well as their applications yield a special attention. For a fractional variational problem based on different types of fractional integral and derivatives operators, corresponding fractional Lagrangian and Hamiltonian formulation and relevant Euler–Lagrange type equations are already presented by scholars. The formulations of fractional variational principles still can be developed more. We make an attempt to generalize the formulations for fractional variational principles. As a result we obtain generalized and complementary fractional variational formulations for extended exponentially fractional integral for example and corresponding Euler–Lagrange equations. Two illustrative examples are presented. It is observed that the formulations are in exact agreement with the Euler–Lagrange equations.

COELIAC TRUNK BRANCHING PATTERN AND VARIATION

Directory of Open Access Journals (Sweden)

Jude Jose Thomson

2017-01-01

Full Text Available BACKGROUND Anatomical variations involving the visceral arteries are common. However, variations in coeliac trunk are usually asymptomatic, they may become important in patients undergoing diagnostic angiography for gastrointestinal bleeding or prior to an operative procedure. This study was useful for knowing the possible morphological variations before an upper abdominal surgery. MATERIALS AND METHODS This was a descriptive study done by cadaveric dissection, conducted on thirty cadavers. The coeliac trunk being examined for its origin, branching pattern, distribution, and variations. Results were statistically analysed and compared with the previous studies. RESULTS In our study, 60% of the coeliac trunk shows variations and 40% have normal branching pattern. A complete absence of coeliac trunk was observed in one case. In the present study the Right inferior phrenic artery arising from coeliac trunk in 2 cases (6.6% and left inferior phrenic artery arising from coeliac trunk in 3 cases (9.9%. Both inferior phrenic arteries are arising from coeliac trunk in 2 cases (6.6%. The common hepatomesenteric trunk and gastro splenic trunk was found in 1 case (3.3%. Hepatosplenic trunk was found in 2 cases (6.6%. In another 2 cases (6.6% gastric and hepatic artery originate from coeliac trunk but splenic artery has a separate origin from abdominal aorta. An absent trunk was also found in 1 case (3.3%. In 5 cases (16.7% showed trifurcation with variation in the branching pattern. CONCLUSION The branching pattern and extreme degree variability in coeliac trunk as brought out in the observations of the present study make it obvious that the present study almost falls in description with previous studies.

Cosmological constants and variations

International Nuclear Information System (INIS)

Barrow, John D

2005-01-01

We review properties of theories for the variation of the gravitation and fine structure 'constants'. We highlight some general features of the cosmological models that exist in these theories with reference to recent quasar data that is consistent with time-variation in the fine structure 'constant' since a redshift of 3.5. The behaviour of a simple class of varying alpha cosmologies is outlined in the light of all the observational constraints. We also discuss some of the consequences of varying 'constants' for oscillating universes and show by means of exact solutions that they appear to evolve monotonically in time even though the scale factor of the universe oscillates

Variational approach to nuclear fluid dynamics

International Nuclear Information System (INIS)

Da Providencia, J.P.; Holzwarth, G.

1983-01-01

A variational derivation of a fluid-dynamical formalism for finite Fermi systems is presented which is based on a single determinant as variational function and does not exclude the possibility of transverse flow. Therefore the explicit specification of the time-odd part has to go beyond the local chi-approximation, while the time-even part is taken in the generalized scaling form. The necessary boundary conditions are derived from the variation of the lagrangian. The results confirm previous simplified approaches to a remarkable degree for quadrupole modes; for other multipolarities the deviations are much less than might be expected according to a sizeable change in the transverse sound speed. (orig.)

Conical differentiability for evolution variational inequalities

Science.gov (United States)

Jarušek, Jiří; Krbec, Miroslav; Rao, Murali; Sokołowski, Jan

The conical differentiability of solutions to the parabolic variational inequality with respect to the right-hand side is proved in the paper. From one side the result is based on the Lipschitz continuity in H {1}/{2},1 (Q) of solutions to the variational inequality with respect to the right-hand side. On the other side, in view of the polyhedricity of the convex cone K={v∈ H;v |Σ c⩾0,v |Σ d=0}, we prove new results on sensitivity analysis of parabolic variational inequalities. Therefore, we have a positive answer to the question raised by Fulbert Mignot (J. Funct. Anal. 22 (1976) 25-32).

A compiler for variational forms

OpenAIRE

Kirby, Robert C.; Logg, Anders

2011-01-01

As a key step towards a complete automation of the finite element method, we present a new algorithm for automatic and efficient evaluation of multilinear variational forms. The algorithm has been implemented in the form of a compiler, the FEniCS Form Compiler FFC. We present benchmark results for a series of standard variational forms, including the incompressible Navier-Stokes equations and linear elasticity. The speedup compared to the standard quadrature-based approach is impressive; in s...

Genomic variation landscape of the human gut microbiome

DEFF Research Database (Denmark)

Schloissnig, Siegfried; Arumugam, Manimozhiyan; Sunagawa, Shinichi

2013-01-01

Whereas large-scale efforts have rapidly advanced the understanding and practical impact of human genomic variation, the practical impact of variation is largely unexplored in the human microbiome. We therefore developed a framework for metagenomic variation analysis and applied it to 252 faecal...... polymorphism rates of 0.11 was more variable between gut microbial species than across human hosts. Subjects sampled at varying time intervals exhibited individuality and temporal stability of SNP variation patterns, despite considerable composition changes of their gut microbiota. This indicates...

Characteristics of seasonal variation and solar activity dependence of the geomagnetic solar quiet daily variation

Science.gov (United States)

Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.

2017-12-01

Characteristics of seasonal variation and solar activity dependence of the X- and Y-components of the geomagnetic solar quiet (Sq) daily variation at Memanbetsu in mid-latitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1-h time resolution from 1957 to 2016. In this analysis, we defined the quiet day when the maximum value of the Kp index is less than 3 for that day. In this analysis, we used the monthly average of the adjusted daily F10.7 corresponding to geomagnetically quiet days. For identification of the monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y), we first determined the baseline of the X and Y components from the average value from 22 to 2 h (LT: local time) for each quiet day. Next, we calculated a deviation from the baseline of the X- and Y-components of the geomagnetic field for each quiet day, and computed the monthly mean value of the deviation for each local time. As a result, Sq-X and Sq-Y shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities, and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and Sq-X and Sq-Y shows almost the linear relationship, but the slope and intercept of the linear fitted line varies as function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The local time dependence of the offset value of Sq-Y at Guam and its seasonal variation suggest a magnetic field produced by inter-hemispheric field-aligned currents (FACs). From the sign of the offset value of Sq-Y, it is infer that the inter-hemispheric FACs flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in

Genetic engineering, a potential aid to conventional plant breeding

International Nuclear Information System (INIS)

Baloch, M.J.; Soomro, B.A.

1993-01-01

To develop improve crop varieties, the most basic elements are crossing of desirable parents to provide genetic variation for evaluation and selection of desirable plants among the progenies. In conventional plant breeding, gene transfer is achieved by back crossing or less frequently by recurrent selection. Both processes take several generations to reach to a point where genetic milieu of the parents remains. Plant breeders also face the most difficult situation when the desired gene is present in the entirely diverse species where wide crosses become inevitable. In addition, genomic disharmony, unfavourable genic interaction and chromosomal instability also account for limited success of wide hybridization in the field crops. Under such circumstances, tissue culture techniques, such as somaclonal variation, Embryo Rescue Technique and Somatic hybridization are the ultimate options. There may be other cases where desired genes are present in entirely different genera or organisms and crossings of donor with recipient is no more a concern. Plant breeders also spend much of their time manipulating quantitatively inherited traits such as yield, that have low heritability. These characters are assumed to be determined by a large number of genes each with minor and additive effects. Direct selection for such traits is less effective. Genetic Engineering approaches like isozymes and Restriction Fragment Length Polymorphism (RFLP) with heritability of 1.0 make the selection very efficient and accurate as indirect selection criteria for quantitatively inherited traits. Hence isozymes and RFLPs techniques can easily be exercised at cellular or seedling stages thus reducing the time and labour oriented screening of plants at maturity. Rather new approach such as polymerase chain reaction (PCR) will also be discussed in this article. (Orig./A.B.)

Variational inference & deep learning: A new synthesis

OpenAIRE

Kingma, D.P.

2017-01-01

In this thesis, Variational Inference and Deep Learning: A New Synthesis, we propose novel solutions to the problems of variational (Bayesian) inference, generative modeling, representation learning, semi-supervised learning, and stochastic optimization.

Variational inference & deep learning : A new synthesis

NARCIS (Netherlands)

Kingma, D.P.

2017-01-01

In this thesis, Variational Inference and Deep Learning: A New Synthesis, we propose novel solutions to the problems of variational (Bayesian) inference, generative modeling, representation learning, semi-supervised learning, and stochastic optimization.

A rare variation of the digastric muscle

Science.gov (United States)

KALNIEV, MANOL; KRASTEV, DIMO; KRASTEV, NIKOLAY; VIDINOV, KALIN; VELTCHEV, LUDMIL; APOSTOLOV, ALEXANDER; MILEVA, MILKA

2013-01-01

The digastric muscle is composed by two muscle bellies: an anterior and a posterior, joined by an intermediate tendon. This muscle is situated in the anterior region of the neck. The region between the hyoid bone and the mandible is divided by an anterior belly into two triangles: the submandibular situated laterally and the submental triangle which is located medially. We found that the anatomical variations described in the literature relate mainly to the anterior belly and consist of differences in shape and attachment of the muscle. During routine dissection in February 2013 in the section hall of the Department of Anatomy and Histology in Medical University – Sofia we came across a very interesting variation of the digastric muscle. The digastric muscles that presented anatomical variations were photographed using a Sony Cyber-shot DSC-T1 camera, with a Carl Zeiss Vario-Tessar lens. We found out bilateral variation of the digastric muscle in one cadaver. The anterior bellies were very thin and insert to the hyoid bone. Two anterior bellies connect each other and thus they formed a loop. The anatomical variations observed of our study related only to the anterior belly, as previously described by other authors. It is very important to consider the occurrence of the above mentioned variations in the digastric muscle when surgical procedures are performed on the anterior region of the neck. PMID:26527971

Nonlinear variational inequalities of semilinear parabolic type

Directory of Open Access Journals (Sweden)

Park Jong-Yeoul

2001-01-01

Full Text Available The existence of solutions for the nonlinear functional differential equation governed by the variational inequality is studied. The regularity and a variation of solutions of the equation are also given.

No variation and low synonymous substitution rates in coral mtDNA despite high nuclear variation

Directory of Open Access Journals (Sweden)

Hellberg Michael E

2006-03-01

Full Text Available Abstract Background The mitochondrial DNA (mtDNA of most animals evolves more rapidly than nuclear DNA, and often shows higher levels of intraspecific polymorphism and population subdivision. The mtDNA of anthozoans (corals, sea fans, and their kin, by contrast, appears to evolve slowly. Slow mtDNA evolution has been reported for several anthozoans, however this slow pace has been difficult to put in phylogenetic context without parallel surveys of nuclear variation or calibrated rates of synonymous substitution that could permit quantitative rate comparisons across taxa. Here, I survey variation in the coding region of a mitochondrial gene from a coral species (Balanophyllia elegans known to possess high levels of nuclear gene variation, and estimate synonymous rates of mtDNA substitution by comparison to another coral (Tubastrea coccinea. Results The mtDNA surveyed (630 bp of cytochrome oxidase subunit I was invariant among individuals sampled from 18 populations spanning 3000 km of the range of B. elegans, despite high levels of variation and population subdivision for allozymes over these same populations. The synonymous substitution rate between B. elegans and T. coccinea (0.05%/site/106 years is similar to that in most plants, but 50–100 times lower than rates typical for most animals. In addition, while substitutions to mtDNA in most animals exhibit a strong bias toward transitions, mtDNA from these corals does not. Conclusion Slow rates of mitochondrial nucleotide substitution result in low levels of intraspecific mtDNA variation in corals, even when nuclear loci vary. Slow mtDNA evolution appears to be the basal condition among eukaryotes. mtDNA substitution rates switch from slow to fast abruptly and unidirectionally. This switch may stem from the loss of just one or a few mitochondrion-specific DNA repair or replication genes.

Variational lower bound on the scattering length

International Nuclear Information System (INIS)

Rosenberg, L.; Spruch, L.

1975-01-01

The scattering length A characterizes the zero-energy scattering of one system by another. It was shown some time ago that a variational upper bound on A could be obtained using methods, of the Rayleigh-Ritz type, which are commonly employed to obtain upper bounds on energy eigenvalues. Here we formulate a method for obtaining a variational lower bound on A. Once again the essential idea is to express the scattering length as a variational estimate plus an error term and then to reduce the problem of bounding the error term to one involving bounds on energy eigenvalues. In particular, the variational lower bound on A is rigorously established provided a certin modified Hamiltonian can be shown to have no discrete states lying below the level of the continuum threshold. It is unfortunately true that necessary conditions for the existence of bound states are not available for multiparticle systems in general. However, in the case of positron-atom scattering the adiabatic approximation can be introduced as an (essentially) solvable comparison problem to rigorously establish the nonexistence of bound states of the modified Hamiltonian. It has recently been shown how the validity of the variational upper bound on A can be maintained when the target ground-state wave function is imprecisely known. Similar methods can be used to maintain the variational lower bound on A. Since the bound is variational, the error in the calculated scattering length will be of second order in the error in the wave function. The use of the adiabatic approximation in the present context places no limitation in principle on the accuracy achievable

Temporal and spatial variations in fly ash quality

Science.gov (United States)

Hower, J.C.; Trimble, A.S.; Eble, C.F.

2001-01-01

Fly ash quality, both as the amount of petrographically distinguishable carbons and in chemistry, varies in both time and space. Temporal variations are a function of a number of variables. Variables can include variations in the coal blend organic petrography, mineralogy, and chemistry; variations in the pulverization of the coal, both as a function of the coal's Hardgrove grindability index and as a function of the maintenance and settings of the pulverizers; and variations in the operating conditions of the boiler, including changes in the pollution control system. Spatial variation, as an instantaneous measure of fly ash characteristics, should not involve changes in the first two sets of variables listed above. Spatial variations are a function of the gas flow within the boiler and ducts, certain flow conditions leading to a tendency for segregation of the less-dense carbons in one portion of the gas stream. Caution must be applied in sampling fly ash. Samples from a single bin, or series of bins, m ay not be representative of the whole fly ash, providing a biased view of the nature of the material. Further, it is generally not possible to be certain about variation until the analysis of the ash is complete. ?? 2001 Elsevier Science B.V. All rights reserved.

Coevolutionary genetic variation in the legume-rhizobium transcriptome.

Science.gov (United States)

Heath, Katy D; Burke, Patricia V; Stinchcombe, John R

2012-10-01

Coevolutionary change requires reciprocal selection between interacting species, where the partner genotypes that are favoured in one species depend on the genetic composition of the interacting species. Coevolutionary genetic variation is manifested as genotype × genotype (G × G) interactions for fitness in interspecific interactions. Although quantitative genetic approaches have revealed abundant evidence for G × G interactions in symbioses, the molecular basis of this variation remains unclear. Here we study the molecular basis of G × G interactions in a model legume-rhizobium mutualism using gene expression microarrays. We find that, like quantitative traits such as fitness, variation in the symbiotic transcriptome may be partitioned into additive and interactive genetic components. Our results suggest that plant genetic variation had the largest influence on nodule gene expression and that plant genotype and the plant genotype × rhizobium genotype interaction determine global shifts in rhizobium gene expression that in turn feedback to influence plant fitness benefits. Moreover, the transcriptomic variation we uncover implicates regulatory changes in both species as drivers of symbiotic gene expression variation. Our study is the first to partition genetic variation in a symbiotic transcriptome and illuminates potential molecular routes of coevolutionary change. © 2012 Blackwell Publishing Ltd.

Causes and significance of variation in mammalian basal metabolism.

Science.gov (United States)

Raichlen, David A; Gordon, Adam D; Muchlinski, Magdalena N; Snodgrass, J Josh

2010-02-01

Mammalian basal metabolic rates (BMR) increase with body mass, whichs explains approximately 95% of the variation in BMR. However, at a given mass, there remains a large amount of variation in BMR. While many researchers suggest that the overall scaling of BMR with body mass is due to physiological constraints, variation at a given body mass may provide clues as to how selection acts on BMR. Here, we examine this variation in BMR in a broad sample of mammals and we test the hypothesis that, across mammals, body composition explains differences in BMR at a given body mass. Variation in BMR is strongly correlated with variation in muscle mass, and both of these variables are correlated with latitude and ambient temperature. These results suggest that selection alters BMR in response to thermoregulatory pressures, and that selection uses muscle mass as a means to generate this variation.

On Bi-Dimensional Second µ-Variation

Directory of Open Access Journals (Sweden)

Ereú Jurancy

2014-12-01

Full Text Available In this paper, we present a generalization of the notion of bounded slope variation for functions defined on a rectangle Iba in ℝ2. Given a strictly increasing function µ-defined in a closed real interval, we introduce the class BVµ,2 (Iba , of functions of bounded second µ-variation on Iba ; and show that this class can be equipped with a norm with respect to which it is a Banach space. We also deal with the important case of factorizable functions in BVµ,2 (Iba and finally we exhibit a relation between this class and the one of double Riemann-Stieltjes integrals of functions of bi-dimensional bounded variation.

Acquiring variation in an artificial language: Children and adults are sensitive to socially conditioned linguistic variation.

Science.gov (United States)

Samara, Anna; Smith, Kenny; Brown, Helen; Wonnacott, Elizabeth

2017-05-01

Languages exhibit sociolinguistic variation, such that adult native speakers condition the usage of linguistic variants on social context, gender, and ethnicity, among other cues. While the existence of this kind of socially conditioned variation is well-established, less is known about how it is acquired. Studies of naturalistic language use by children provide various examples where children's production of sociolinguistic variants appears to be conditioned on similar factors to adults' production, but it is difficult to determine whether this reflects knowledge of sociolinguistic conditioning or systematic differences in the input to children from different social groups. Furthermore, artificial language learning experiments have shown that children have a tendency to eliminate variation, a process which could potentially work against their acquisition of sociolinguistic variation. The current study used a semi-artificial language learning paradigm to investigate learning of the sociolinguistic cue of speaker identity in 6-year-olds and adults. Participants were trained and tested on an artificial language where nouns were obligatorily followed by one of two meaningless particles and were produced by one of two speakers (one male, one female). Particle usage was conditioned deterministically on speaker identity (Experiment 1), probabilistically (Experiment 2), or not at all (Experiment 3). Participants were given tests of production and comprehension. In Experiments 1 and 2, both children and adults successfully acquired the speaker identity cue, although the effect was stronger for adults and in Experiment 1. In addition, in all three experiments, there was evidence of regularization in participants' productions, although the type of regularization differed with age: children showed regularization by boosting the frequency of one particle at the expense of the other, while adults regularized by conditioning particle usage on lexical items. Overall, results

Solid mechanics a variational approach

CERN Document Server

Dym, Clive L

2013-01-01

Solid Mechanics: A Variational Approach, Augmented Edition presents a lucid and thoroughly developed approach to solid mechanics for students engaged in the study of elastic structures not seen in other texts currently on the market. This work offers a clear and carefully prepared exposition of variational techniques as they are applied to solid mechanics. Unlike other books in this field, Dym and Shames treat all the necessary theory needed for the study of solid mechanics and include extensive applications. Of particular note is the variational approach used in developing consistent structural theories and in obtaining exact and approximate solutions for many problems.  Based on both semester and year-long courses taught to undergraduate seniors and graduate students, this text is geared for programs in aeronautical, civil, and mechanical engineering, and in engineering science. The authors’ objective is two-fold: first, to introduce the student to the theory of structures (one- and two-dimensional) as ...

Size variation in Middle Pleistocene humans.

Science.gov (United States)

Arsuaga, J L; Carretero, J M; Lorenzo, C; Gracia, A; Martínez, I; Bermúdez de Castro, J M; Carbonell, E

1997-08-22

It has been suggested that European Middle Pleistocene humans, Neandertals, and prehistoric modern humans had a greater sexual dimorphism than modern humans. Analysis of body size variation and cranial capacity variation in the large sample from the Sima de los Huesos site in Spain showed instead that the sexual dimorphism is comparable in Middle Pleistocene and modern populations.

VariVis: a visualisation toolkit for variation databases

Directory of Open Access Journals (Sweden)

Smith Timothy D

2008-04-01

Full Text Available Abstract Background With the completion of the Human Genome Project and recent advancements in mutation detection technologies, the volume of data available on genetic variations has risen considerably. These data are stored in online variation databases and provide important clues to the cause of diseases and potential side effects or resistance to drugs. However, the data presentation techniques employed by most of these databases make them difficult to use and understand. Results Here we present a visualisation toolkit that can be employed by online variation databases to generate graphical models of gene sequence with corresponding variations and their consequences. The VariVis software package can run on any web server capable of executing Perl CGI scripts and can interface with numerous Database Management Systems and "flat-file" data files. VariVis produces two easily understandable graphical depictions of any gene sequence and matches these with variant data. While developed with the goal of improving the utility of human variation databases, the VariVis package can be used in any variation database to enhance utilisation of, and access to, critical information.

Variational estimates of point-kinetics parameters

International Nuclear Information System (INIS)

Favorite, J.A.; Stacey, W.M. Jr.

1995-01-01

Variational estimates of the effect of flux shifts on the integral reactivity parameter of the point-kinetics equations and on regional power fractions were calculated for a variety of localized perturbations in two light water reactor (LWR) model problems representing a small, tightly coupled core and a large, loosely coupled core. For the small core, the flux shifts resulting from even relatively large localized reactivity changes (∼600 pcm) were small, and the standard point-kinetics approximation estimates of reactivity were in error by only ∼10% or less, while the variational estimates were accurate to within ∼1%. For the larger core, significant (>50%) flux shifts occurred in response to local perturbations, leading to errors of the same magnitude in the standard point-kinetics approximation of the reactivity worth. For positive reactivity, the error in the variational estimate of reactivity was only a few percent in the larger core, and the resulting transient power prediction was 1 to 2 orders of magnitude more accurate than with the standard point-kinetics approximation. For a large, local negative reactivity insertion resulting in a large flux shift, the accuracy of the variational estimate broke down. The variational estimate of the effect of flux shifts on reactivity in point-kinetics calculations of transients in LWR cores was found to generally result in greatly improved accuracy, relative to the standard point-kinetics approximation, the exception being for large negative reactivity insertions with large flux shifts in large, loosely coupled cores

Gauging Variational Inference

Energy Technology Data Exchange (ETDEWEB)

Chertkov, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ahn, Sungsoo [Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea, Republic of); Shin, Jinwoo [Korea Advanced Inst. Science and Technology (KAIST), Daejeon (Korea, Republic of)

2017-05-25

Computing partition function is the most important statistical inference task arising in applications of Graphical Models (GM). Since it is computationally intractable, approximate methods have been used to resolve the issue in practice, where meanfield (MF) and belief propagation (BP) are arguably the most popular and successful approaches of a variational type. In this paper, we propose two new variational schemes, coined Gauged-MF (G-MF) and Gauged-BP (G-BP), improving MF and BP, respectively. Both provide lower bounds for the partition function by utilizing the so-called gauge transformation which modifies factors of GM while keeping the partition function invariant. Moreover, we prove that both G-MF and G-BP are exact for GMs with a single loop of a special structure, even though the bare MF and BP perform badly in this case. Our extensive experiments, on complete GMs of relatively small size and on large GM (up-to 300 variables) confirm that the newly proposed algorithms outperform and generalize MF and BP.

Causes and consequences of chromatin variation between inbred mice.

Directory of Open Access Journals (Sweden)

Mona Hosseini

2013-06-01

Full Text Available Variation at regulatory elements, identified through hypersensitivity to digestion by DNase I, is believed to contribute to variation in complex traits, but the extent and consequences of this variation are poorly characterized. Analysis of terminally differentiated erythroblasts in eight inbred strains of mice identified reproducible variation at approximately 6% of DNase I hypersensitive sites (DHS. Only 30% of such variable DHS contain a sequence variant predictive of site variation. Nevertheless, sequence variants within variable DHS are more likely to be associated with complex traits than those in non-variant DHS, and variants associated with complex traits preferentially occur in variable DHS. Changes at a small proportion (less than 10% of variable DHS are associated with changes in nearby transcriptional activity. Our results show that whilst DNA sequence variation is not the major determinant of variation in open chromatin, where such variants exist they are likely to be causal for complex traits.

Multistep Hybrid Extragradient Method for Triple Hierarchical Variational Inequalities

Directory of Open Access Journals (Sweden)

Zhao-Rong Kong

2013-01-01

Full Text Available We consider a triple hierarchical variational inequality problem (THVIP, that is, a variational inequality problem defined over the set of solutions of another variational inequality problem which is defined over the intersection of the fixed point set of a strict pseudocontractive mapping and the solution set of the classical variational inequality problem. Moreover, we propose a multistep hybrid extragradient method to compute the approximate solutions of the THVIP and present the convergence analysis of the sequence generated by the proposed method. We also derive a solution method for solving a system of hierarchical variational inequalities (SHVI, that is, a system of variational inequalities defined over the intersection of the fixed point set of a strict pseudocontractive mapping and the solution set of the classical variational inequality problem. Under very mild conditions, it is proven that the sequence generated by the proposed method converges strongly to a unique solution of the SHVI.

Variational calculus with constraints on general algebroids

Energy Technology Data Exchange (ETDEWEB)

Grabowska, Katarzyna [Physics Department, Division of Mathematical Methods in Physics, University of Warsaw, Hoza 69, 00-681 Warszawa (Poland); Grabowski, Janusz [Institute of Mathematics, Polish Academy of Sciences, Sniadeckich 8, PO Box 21, 00-956 Warszawa (Poland)], E-mail: konieczn@fuw.edu.pl, E-mail: jagrab@impan.gov.pl

2008-05-02

Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM.

Variational calculus with constraints on general algebroids

International Nuclear Information System (INIS)

Grabowska, Katarzyna; Grabowski, Janusz

2008-01-01

Variational calculus on a vector bundle E equipped with a structure of a general algebroid is developed, together with the corresponding analogs of Euler-Lagrange equations. Constrained systems are introduced in the variational and geometrical settings. The constrained Euler-Lagrange equations are derived for analogs of holonomic, vakonomic and nonholonomic constraints. This general model covers the majority of first-order Lagrangian systems which are present in the literature and reduces to the standard variational calculus and the Euler-Lagrange equations in classical mechanics for E = TM

Solar UV radiation variations and their stratospheric and climatic effects

Science.gov (United States)

Donnelly, R. F.; Heath, D. F.

1985-01-01

Nimbus-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. Nimbus-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.

Variations in the small-scale galactic magnetic field and short time-scale intensity variations of extragalactic radio sources

International Nuclear Information System (INIS)

Simonetti, J.H.

1985-01-01

Structure functions of the Faraday rotation measures (RMs) of extragalactic radio sources are used to investigate variations in the interstellar magnetic field on length scales of approx.0.01 to 100 pc. Model structure functions derived assuming a power-law power spectrum of irregularities in n/sub e/B, are compared with those observed. The results indicate an outer angular scale for RM variations of approximately less than or equal to 5 0 and evidence for RM variations on scales as small as 1'. Differences in the variance of n/sub e/B fluctuations for various lines of sight through the Galaxy are found. Comparison of pulsar scintillations in right- and left-circular polarizations yield an upper limit to the variations in n/sub e/ on a length scale of approx.10 11 cm. RMs were determined through high-velocity molecular flows in galactic star-formation regions, with the goal of constraining magnetic fields in and near the flows. RMs of 7 extragalactic sources with a approx.20 arcmin wide area seen through Cep A, fall in two groups separated by approx.150 rad m -2 - large given our knowledge of RM variations on small angular scales and possibly a result of the anisotropy of the high-velocity material

Comparison of respiratory-induced variations in photoplethysmographic signals

International Nuclear Information System (INIS)

Li, Jin; Jin, Jie; Chen, Xiang; Sun, Weixin; Guo, Ping

2010-01-01

Photoplethysmography (PPG) is an optical method for detecting blood volume changes in tissue. Respiratory-induced intensity, frequency and amplitude variations are contained in the PPG signal; thus, an understanding of the relationships between all of these variations and respiration is essential to advancing respiration monitoring based on PPG. This study investigated correlations between respiratory-induced variations extracted from PPG and simultaneous respiratory signals. PPG signals were recorded from 28 healthy subjects under eight different conditions. Six respiratory-induced variations, i.e. the period of the systole, diastole and pulse, the amplitude of the systole and diastole, and the intensity variation, were determined from the PPG signal. The results indicate that, compared with the period of the pulse, the period of the systole and diastole correlates weakly with respiration; the amplitude of the diastole has a stronger correlation with respiration than the amplitude of the systole. For men, when the respiratory rate is less than 10 breaths min −1 , the period of the pulse has the strongest correlation with respiration, whereas up to or above 15 breaths min −1 , the intensity variation becomes strongest in the sitting posture, while the amplitude of the diastole is strongest in the supine posture. For women, compared with the other variations, the period of the pulse has nearly the strongest correlation with respiration, independent of respiratory rate or posture

Variational continuum multiphase poroelasticity theory and applications

CERN Document Server

Serpieri, Roberto

2017-01-01

This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics. The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations. It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the...

Strategic Approach in Enhancing the Utilization of GGH Facilities Towards High Impact of Agrobiotechnology

International Nuclear Information System (INIS)

Azhar Mohamad; Ahsanulkhaliqin Abdul Wahab

2013-01-01

Gamma greenhouse (GGH) is associates with chronic radiation activities in life organism. The facility is equipped with 137 Cs source with relatively high energy (t 1/2 =30.1 years). The energy associated with gamma radiation is high enough to break the molecular bonds and ionize atoms without affecting structure of the atomic nucleus (avoiding induction of radioactivity). Nuclear Malaysia is the only institute that provides the facility for Research and Development chronic mutagenesis activities in Malaysia. Chronic gamma irradiation is an exposure of ionizing radiation over an extended period (hours, weeks, months) depending on their nature, sensitivity and research requirements. The alteration by chronic irradiation is tremendous, resulting in physical appearance, changes in molecular structures and metabolism changes. These changes are randomly events, inheritable, and the stability depends on cell damages after irradiation at molecular level. In agrobiotechnology, chronic gamma irradiation produces a wider mutation spectrum and useful for minimizing radiation damages towards obtaining new improved traits for commercial values. Continuous expose at low dose of gamma irradiation resulting in considerably elevated somaclonal variation frequency without negative effects on natural response. However, there is still lack of users especially researchers in Malaysia to utilize the facility. Strategic approaches as seminars, public talk, direct connections and engagement through collaboration, research activities and road show approaches are expected to bring more consumers in conveying high impact activities at GGH. (author)

Assessing environmental impacts of genetically modified plants on non-target organisms: The relevance of in planta studies.

Science.gov (United States)

Arpaia, Salvatore; Birch, A Nicholas E; Kiss, Jozsef; van Loon, Joop J A; Messéan, Antoine; Nuti, Marco; Perry, Joe N; Sweet, Jeremy B; Tebbe, Christoph C

2017-04-01

In legal frameworks worldwide, genetically modified plants (GMPs) are subjected to pre-market environmental risk assessment (ERA) with the aim of identifying potential effects on the environment. In the European Union, the EFSA Guidance Document introduces the rationale that GMPs, as well as their newly produced metabolites, represent the potential stressor to be evaluated during ERA. As a consequence, during several phases of ERA for cultivation purposes, it is considered necessary to use whole plants or plant parts in experimental protocols. The importance of in planta studies as a strategy to address impacts of GMPs on non-target organisms is demonstrated, to evaluate both effects due to the intended modification in plant phenotype (e.g. expression of Cry proteins) and effects due to unintended modifications in plant phenotype resulting from the transformation process (e.g. due to somaclonal variations or pleiotropic effects). In planta tests are also necessary for GMPs in which newly expressed metabolites cannot easily be studied in vitro. This paper reviews the scientific literature supporting the choice of in planta studies as a fundamental tool in ERA of GMPs in cultivation dossiers; the evidence indicates they can realistically mimic the ecological relationships occurring in their receiving environments and provide important insights into the biology and sustainable management of GMPs. Copyright © 2017 Elsevier B.V. All rights reserved.

Increasing Al-Tolerance of Sugarcane Using Ethyl Methane Sulphonate and In Vitro Selection in the Low pH Media

Directory of Open Access Journals (Sweden)

Ragapadmi Purnamaningsih

2016-01-01

Full Text Available Increased production of sugarcane in Indonesia can be done with extensification sugarcane plantations which largely dominated by acidic upland red-yellow podzolic soil. High aluminium (Al content and low pH of the soil can inhibit plant growth and development. Tolerant sugarcane in acid soil is the most efficient way, but the adaptive variety is still limited. In vitro culture technique can increase genetic variability to assemble new varieties through somaclonal variation combined with mutation using ethyl methane sulphonate (EMS. The new characters was directed by in vitro selection using AlCl3.6H2O with pH = 4 as a component of selection for resistance to high aluminium. VMC 7616 and PS 862 varieties were used as materials. Mutation induced using EMS at concentrations of 0.1%, 0.3%, and 0.5% for 30, 60 and 120 minutes. Plantlets mutant obtained through callus formation, immersion callus in EMS, in vitro selection, and regeneration of callus. Result of study showed that the long immersion in the EMS solution caused greater damage to the cells, as indicated by the change in callus colour. Callus immersion time in EMS gave greater influence to regeneration compared to concentration of EMS. PS 862 had higher Al tolerance than VMC 7616. Rooting of shoot induced using indole-3-butyric acid (IBA 3 mg/L.

A survey of variational principles

International Nuclear Information System (INIS)

Lewins, J.D.

1993-01-01

The survey of variational principles has ranged widely from its starting point in the Lagrange multiplier to optimisation principles. In an age of digital computation, these classic methods can be adapted to improve such calculations. We emphasize particularly the advantage of basing finite element methods on variational principles, especially if, as maximum and minimum principles, these can provide bounds and hence estimates of accuracy. The non-symmetric (and hence stationary rather than extremum principles) are seen however to play a significant role in optimisation theory. (Orig./A.B.)

Stochastic variational approach to minimum uncertainty states

Energy Technology Data Exchange (ETDEWEB)

Illuminati, F.; Viola, L. [Dipartimento di Fisica, Padova Univ. (Italy)

1995-05-21

We introduce a new variational characterization of Gaussian diffusion processes as minimum uncertainty states. We then define a variational method constrained by kinematics of diffusions and Schroedinger dynamics to seek states of local minimum uncertainty for general non-harmonic potentials. (author)

Sources of Variation in Creep Testing

Science.gov (United States)

Loewenthal, William S.; Ellis, David L.

2011-01-01

Creep rupture is an important material characteristic for the design of rocket engines. It was observed during the characterization of GRCop-84 that the complete data set had nearly 4 orders of magnitude of scatter. This scatter likely confounded attempts to determine how creep performance was influenced by manufacturing. It was unclear if this variation was from the testing, the material, or both. Sources of variation were examined by conducting tests on identically processed specimens at the same specified stresses and temperatures. Significant differences existed between the five constant-load creep frames. The specimen temperature was higher than the desired temperature by as much as 43 C. It was also observed that the temperature gradient was up to 44 C. Improved specimen temperature control minimized temperature variations. The data from additional tests demonstrated that the results from all five frames were comparable. The variation decreased to 1/2 order of magnitude from 2 orders of magnitude for the baseline data set. Independent determination of creep rates in a reference load frame closely matched the creep rates determined after the modifications. Testing in helium tended to decrease the sample temperature gradient, but helium was not a significant improvement over vacuum.

Biological variation in tPA-induced plasma clot lysis time.

Science.gov (United States)

Talens, Simone; Malfliet, Joyce J M C; Rudež, Goran; Spronk, Henri M H; Janssen, Nicole A H; Meijer, Piet; Kluft, Cornelis; de Maat, Moniek P M; Rijken, Dingeman C

2012-10-01

Hypofibrinolysis is a risk factor for venous and arterial thrombosis, and can be assessed by using a turbidimetric tPA-induced clot lysis time (CLT) assay. Biological variation in clot lysis time may affect the interpretation and usefulness of CLT as a risk factor for thrombosis. Sufficient information about assay variation and biological variation in CLT is not yet available. Thus, this study aimed to determine the analytical, within-subject and between-subject variation in CLT. We collected blood samples from 40 healthy individuals throughout a period of one year (average 11.8 visits) and determined the CLT of each plasma sample in duplicate. The mean (± SD) CLT was 83.8 (± 11.1) minutes. The coefficients of variation for total variation, analytical variation, within-subject variation and between-subject variation were 13.4%, 2.6%, 8.2% and 10.2%, respectively. One measurement can estimate the CLT that does not deviate more than 20% from its true value. The contribution of analytical variation to the within-subject variation was 5.0%, the index of individuality was 0.84 and the reference change value was 23.8%. The CLT was longer in the morning compared to the afternoon and was slightly longer in older individuals (> 40 years) compared to younger (≤40 years) individuals. There was no seasonal variation in CLT and no association with air pollution. CLT correlated weakly with fibrinogen, C-reactive protein, prothrombin time and thrombin generation. This study provides insight into the biological variation of CLT, which can be used in future studies testing CLT as a potential risk factor for thrombosis.

Variations in automatically recorded rumination time as explained by variations in intake of dietary fractions and milk production, and between-cow variation.

Science.gov (United States)

Byskov, M V; Nadeau, E; Johansson, B E O; Nørgaard, P

2015-06-01

Individual recording of rumination time (RT) is now possible in commercial dairy herds, through development of a microphone-based sensor, which is able to record RT by the sound of rumination activity. The objectives of this study were to examine the relationship between daily RT and intakes of different dietary fractions, the relationship between RT in minutes per kilogram of dry matter intake (DMI) and milk production, and to examine the variation in RT within and between mid-lactating dairy cows. Data from 3 production trials were used in which a total of 27 different diets were fed. The data contained 761, 290, and 203 daily recordings of RT, milk yield, milk components, DMI, and intake of dietary fractions recorded on 29, 26, and 24 Holstein and Swedish Red cows from trials 1, 2, and 3, respectively. The dietary fractions included forage neutral detergent fiber (NDF), concentrate NDF, crude protein, sugar, starch, and the remaining fraction represented by organic matter--(forage NDF+concentrate NDF+crude protein+sugar+starch). The relationship between the dietary fractions and RT was analyzed in 2 steps. In step 1, the dietary fractions, which were significantly related to RT, were selected and simultaneously checked for multicollinearity between the dietary components; in step 2, a multivariate model, including the effect of repeated measurements, the main effect of the selected dietary fractions from step 1, random effects of cow(trial) and trial, and information on breed, days in milk, and parity was used to analyze the relationship between RT and the selected dietary fractions. Relationships between RT in minutes per kilogram of DMI and milk yield and milk components were analyzed, using the same multivariate model as in step 2. Approximately 32% of the variation in daily RT could be explained by variations in intakes of the dietary fractions, whereas 48% of the total variation in RT was accounted for by individual variations between cows. Intakes of

Solar cycle variations of geocoronal balmer α emission

International Nuclear Information System (INIS)

Nossal, S.; Reynolds, R.J.; Roesler, F.L.; Scherb, F.

1993-01-01

Observations of the geocoronal Balmer in nightglow have been made from Wisconsin for more than a solar cycle with an internally consistent intensity reference to standard astronomical nebulae. These measurements were made with a double etalon, pressure-scanned, 15-cm aperture Fabry-Perot interferometer. The resulting long time data provides an opportunity to examine solar cycle influence on the mid-latitude exosphere and to address accompanying questions concerning the degree to which the exosphere is locally static or changing. The exospheric Balmer α absolute intensity measurements reported here show no statistically significant variations throughout the solar cycle when the variation with viewing geometry is removed by normalizing the data to reference exospheric model predictions by Anderson et al. However, the relative intensity dependence on solar depression angle does show a solar cycle variation. This variation suggests a possible related variation in the exospheric hydrogen density profile, although other interpretations are also possible. The results suggest that additional well-calibrated data taken over a longer time span could probe low-amplitude variations over the solar cycle and test predictions of a slow monotonic increase in exospheric hydrogen arising from greenhouse gases. 21 refs., 9 figs., 2 tabs

Coupled variations of fundamental couplings and primordial nucleosynthesis

International Nuclear Information System (INIS)

Coc, Alain; Nunes, Nelson J.; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth

2006-10-01

The effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only 4 He, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. These constraints are then translated into constraints on the time variation of the Yukawa couplings and the fine structure constant. Furthermore, we show that a variation of the deuterium binding energy is able to reconcile the 7 Li abundance deduced from the WMAP analysis with its spectroscopically determined value while maintaining concordance with D and 4 He. (authors)

Introduction to the calculus of variations

CERN Document Server

Sagan, Hans

1992-01-01

Excellent text provides basis for thorough understanding of the problems, methods and techniques of the calculus of variations and prepares readers for the study of modern optimal control theory. Treatment limited to extensive coverage of single integral problems in one and more unknown functions. Carefully chosen variational problems and over 400 exercises. ""Should find wide acceptance as a text and reference.""-American Mathematical Monthly. 1969 edition. Bibliography.

Macroinvertebrate variation in endorheic depression wetlands in ...

African Journals Online (AJOL)

Aquatic macroinvertebrates are rarely used in wetland assessments due to their variation. However, in terms of biodiversity, these invertebrates form an important component of wetland fauna. Spatial and temporal variation of macroinvertebrate assemblages in endorheic depressions (locally referred to as 'pans') in ...

Ranking of Unwarranted Variations in Healthcare Treatments

NARCIS (Netherlands)

Moes, Herry; Brekelmans, Ruud; Hamers, Herbert; Hasaart, F.

2017-01-01

In this paper, we introduce a framework designed to identify and rank possible unwarranted variation of treatments in healthcare. The innovative aspect of this framework is a ranking procedure that aims to identify healthcare institutions where unwarranted variation is most severe, and diagnosis

Interobserver delineation variation in lung tumour stereotacticbody radiotherapy

DEFF Research Database (Denmark)

Persson, G. F.; Nygaard, D. E.; Hollensen, Christian

2012-01-01

the interobserver delineation variation for stereotactic body radiotherapy (SBRT) of peripheral lung tumours using a cross-sectional study design. Methods 22 consecutive patients with 26 tumours were included. Positron emission tomography/CT scans were acquired for planning of SBRT. Three oncologists and three......-sectional analysis of delineation variation for peripheral lung tumours referred for SBRT, establishing the evidence that interobserver variation is very small for these tumours....

Contingent negative variation of mood disorder patients

Institute of Scientific and Technical Information of China (English)

Yingzhi Lu; Wenbin Zong; Qingtao Ren; Jinyu Pu; Jun Chen; Juan Li; Xingshi Chen; Yong Wang

2011-01-01

Studies on brain-evoked potential and contingent negative variation (CNV) in mood disorder remain controversial. To date, no CNV difference between unipolar and bipolar depression has been reported. Brain-evoked potentials were measured in the present study to analyze CNV in three subtypes of mood disorder (mania, unipolar depression, and bipolar depression), and these results were compared with normal controls. In the mania group, CNV amplitude B was greater than in controls, and the depression group exhibited lower CNV amplitude B and smaller A-S'2 area, and prolonged post-imperative negative variation latency. The CNV comparison between unipolar and bipolar depression found that the prolonged post-imperative negative variation latency was only in unipolar depression. These results suggest that prolonged post-imperative negative variation latency is a characteristic of unipolar depression, and CNV amplitude change is a state characteristic of mood disorder patients.

Partitioning sources of variation in vertebrate species richness

Science.gov (United States)

Boone, R.B.; Krohn, W.B.

2000-01-01

Aim: To explore biogeographic patterns of terrestrial vertebrates in Maine, USA using techniques that would describe local and spatial correlations with the environment. Location: Maine, USA. Methods: We delineated the ranges within Maine (86,156 km2) of 275 species using literature and expert review. Ranges were combined into species richness maps, and compared to geomorphology, climate, and woody plant distributions. Methods were adapted that compared richness of all vertebrate classes to each environmental correlate, rather than assessing a single explanatory theory. We partitioned variation in species richness into components using tree and multiple linear regression. Methods were used that allowed for useful comparisons between tree and linear regression results. For both methods we partitioned variation into broad-scale (spatially autocorrelated) and fine-scale (spatially uncorrelated) explained and unexplained components. By partitioning variance, and using both tree and linear regression in analyses, we explored the degree of variation in species richness for each vertebrate group that Could be explained by the relative contribution of each environmental variable. Results: In tree regression, climate variation explained richness better (92% of mean deviance explained for all species) than woody plant variation (87%) and geomorphology (86%). Reptiles were highly correlated with environmental variation (93%), followed by mammals, amphibians, and birds (each with 84-82% deviance explained). In multiple linear regression, climate was most closely associated with total vertebrate richness (78%), followed by woody plants (67%) and geomorphology (56%). Again, reptiles were closely correlated with the environment (95%), followed by mammals (73%), amphibians (63%) and birds (57%). Main conclusions: Comparing variation explained using tree and multiple linear regression quantified the importance of nonlinear relationships and local interactions between species

Noninvasive pulse pressure variation and stroke volume variation to predict fluid responsiveness at multiple thresholds : a prospective observational study

NARCIS (Netherlands)

Vos, Jaap Jan; Poterman, Marieke; Papineau Salm, Pieternel; Van Amsterdam, Kai; Struys, Michel M. R. F.; Scheeren, Thomas W. L.; Kalmar, Alain F.

2015-01-01

Pulse pressure variation (PPV) and stroke volume variation (SVV) are dynamic preload variables that can be measured noninvasively to assess fluid responsiveness (FR) in anesthetized patients with mechanical ventilation. Few studies have examined the effectiveness of predicting FR according to the

Total variation-based neutron computed tomography

Science.gov (United States)

Barnard, Richard C.; Bilheux, Hassina; Toops, Todd; Nafziger, Eric; Finney, Charles; Splitter, Derek; Archibald, Rick

2018-05-01

We perform the neutron computed tomography reconstruction problem via an inverse problem formulation with a total variation penalty. In the case of highly under-resolved angular measurements, the total variation penalty suppresses high-frequency artifacts which appear in filtered back projections. In order to efficiently compute solutions for this problem, we implement a variation of the split Bregman algorithm; due to the error-forgetting nature of the algorithm, the computational cost of updating can be significantly reduced via very inexact approximate linear solvers. We present the effectiveness of the algorithm in the significantly low-angular sampling case using synthetic test problems as well as data obtained from a high flux neutron source. The algorithm removes artifacts and can even roughly capture small features when an extremely low number of angles are used.

Variational integrators for reduced magnetohydrodynamics

Energy Technology Data Exchange (ETDEWEB)

Kraus, Michael, E-mail: michael.kraus@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Boltzmannstraße 2, 85748 Garching (Germany); Technische Universität München, Zentrum Mathematik, Boltzmannstraße 3, 85748 Garching (Germany); Tassi, Emanuele, E-mail: tassi@cpt.univ-mrs.fr [Aix-Marseille Université, Université de Toulon, CNRS, CPT, UMR 7332, 163 avenue de Luminy, case 907, 13288 cedex 9 Marseille (France); Grasso, Daniela, E-mail: daniela.grasso@infm.polito.it [ISC-CNR and Politecnico di Torino, Dipartimento Energia, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

2016-09-15

Reduced magnetohydrodynamics is a simplified set of magnetohydrodynamics equations with applications to both fusion and astrophysical plasmas, possessing a noncanonical Hamiltonian structure and consequently a number of conserved functionals. We propose a new discretisation strategy for these equations based on a discrete variational principle applied to a formal Lagrangian. The resulting integrator preserves important quantities like the total energy, magnetic helicity and cross helicity exactly (up to machine precision). As the integrator is free of numerical resistivity, spurious reconnection along current sheets is absent in the ideal case. If effects of electron inertia are added, reconnection of magnetic field lines is allowed, although the resulting model still possesses a noncanonical Hamiltonian structure. After reviewing the conservation laws of the model equations, the adopted variational principle with the related conservation laws is described both at the continuous and discrete level. We verify the favourable properties of the variational integrator in particular with respect to the preservation of the invariants of the models under consideration and compare with results from the literature and those of a pseudo-spectral code.

Isozyme variation in wild and cultivated pineapple

Science.gov (United States)

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Genetic variation in bovine milk fat composition

NARCIS (Netherlands)

Stoop, W.M.

2009-01-01

In her thesis, Stoop shows that there is considerable genetic variation in milk fat composition, which opens opportunities to improve milk fat composition by selective breeding. Short and medium chain fatty acids had high heritabilities, whereas variation due to herd (mainly feed effects) was

Genetic variation between ecotypic populations of Chloris ...

African Journals Online (AJOL)

Genetic variation between ecotypic populations of Chloris roxburghiana grass detected through RAPD analysis. ... frequency indicated that the four populations of C. roxburghiana were genetically distinct, probably as a result of variation in soil fertility, geographical isolation and socio-ecological history of the study sites.

Spatial Distribution and Semiannual Variation of Cold-Dense Plasma Sheet

Science.gov (United States)

Bai, Shichen; Shi, Quanqi; Tian, Anmin; Nowada, Motoharu; Degeling, Alexander W.; Zhou, Xu-Zhi; Zong, Qiu-Gang; Rae, I. Jonathan; Fu, Suiyan; Zhang, Hui; Pu, Zuyin; Fazakerly, Andrew N.

2018-01-01

The cold-dense plasma sheet (CDPS) plays an important role in the entry process of the solar wind plasma into the magnetosphere. Investigating the seasonal variation of CDPS occurrences will help us better understand the long-term variation of plasma exchange between the solar wind and magnetosphere, but any seasonal variation of CDPS occurrences has not yet been reported in the literature. In this paper, we investigate the seasonal variation of the occurrence rate of CDPS using Geotail data from 1996 to 2015 and find a semiannual variation of the CDPS occurrences. Given the higher probability of solar wind entry under stronger northward interplanetary magnetic field (IMF) conditions, 20 years of IMF data (1996-2015) are used to investigate the seasonal variation of IMF Bz under northward IMF conditions. We find a semiannual variation of IMF Bz, which is consistent with the Russell-McPherron (R-M) effect. We therefore suggest that the semiannual variation of CDPS may be related to the R-M effect.

Variational model for one-dimensional quantum magnets

Science.gov (United States)

Kudasov, Yu. B.; Kozabaranov, R. V.

2018-04-01

A new variational technique for investigation of the ground state and correlation functions in 1D quantum magnets is proposed. A spin Hamiltonian is reduced to a fermionic representation by the Jordan-Wigner transformation. The ground state is described by a new non-local trial wave function, and the total energy is calculated in an analytic form as a function of two variational parameters. This approach is demonstrated with an example of the XXZ-chain of spin-1/2 under a staggered magnetic field. Generalizations and applications of the variational technique for low-dimensional magnetic systems are discussed.

Gyarmati’s Variational Principle of Dissipative Processes

Directory of Open Access Journals (Sweden)

József Verhás

2014-04-01

Full Text Available Like in mechanics and electrodynamics, the fundamental laws of the thermodynamics of dissipative processes can be compressed into Gyarmati’s variational principle. This variational principle both in its differential (local and in integral (global forms was formulated by Gyarmati in 1965. The consistent application of both the local and the global forms of Gyarmati’s principle provides all the advantages throughout explicating the theory of irreversible thermodynamics that are provided in the study of mechanics and electrodynamics by the corresponding classical variational principles, e.g., Gauss’ differential principle of least constraint or Hamilton’s integral principle.

Self-potential variations preceding earthquakes in central california

International Nuclear Information System (INIS)

Corwin, R.F.; Morrison, H.G.

1977-01-01

Two earthquakes in central California were preceded by anomalous variations in the horizontal electric field (self-potential) of the earth. The first variation was an anomaly of 90 mV amplitude across electrode dipoles of 630 and 640 m, which began 55 days before an earthquake of M=5, located 37 km NW of the dipoles. The second variation had an amplitude of 4 mV across a 300 m dipole, and began 110 hours before an event of M=2.4 located on the San Andreas fault, 2.5 km from the dipole. Streaming potentials generated by the flow of groundwater into a dilatant zone are proposed as a possible mechanism for the observed variations

Variational principle in quantum mechanics

International Nuclear Information System (INIS)

Popiez, L.

1986-01-01

The variational principle in a standard, path integral formulation of quantum mechanics (as proposed by Dirac and Feynman) appears only in the context of a classical limit n to 0 and manifests itself through the method of abstract stationary phase. Symbolically it means that a probability amplitude averaged over trajectories denotes a classical evolution operator for points in a configuration space. There exists, however, the formulation of quantum dynamics in which variational priniple is one of basic postulates. It is explained that the translation between stochastic and quantum mechanics in this case can be understood as in Nelson's stochastic mechanics

Biological variation of thyroid autoantibodies and thyroglobulin

DEFF Research Database (Denmark)

Jensen, Esther; Petersen, Per Hyltoft; Blaabjerg, Ole

2007-01-01

BACKGROUND: It has been shown that the level of serum thyroid antibodies affects serum thyrotropin (TSH) concentrations in men and women, and that these autoantibodies in combination with serum TSH are predictive of future thyroid disease. As the biological variation of these autoantibodies.......5-258 kIU/L), the CV biological was 11.3%, while the CV analytical was 10.6%. For TgAb (5.6 to 148 kIU/L) CV biological was 8.5% and CV analytical was 9.0%. The woman with TRAb had a CV biological of 4.8%, while the analytical variation in duplicates was 3.9% at a level of 2.8 IU/L. CONCLUSIONS......: It is possible to measure TPOAb and TgAb in all samples with the AutoDELFIA. There is no systematic variation in autoantibodies during the menstrual cycle. The biological coefficient of variation for TPOAb and TgAb was 11.3% and 8.5%, respectively...

Explaining mutualism variation: a new evolutionary paradox?

Science.gov (United States)

Heath, Katy D; Stinchcombe, John R

2014-02-01

The paradox of mutualism is typically framed as the persistence of interspecific cooperation, despite the potential advantages of cheating. Thus, mutualism research has tended to focus on stabilizing mechanisms that prevent the invasion of low-quality partners. These mechanisms alone cannot explain the persistence of variation for partner quality observed in nature, leaving a large gap in our understanding of how mutualisms evolve. Studying partner quality variation is necessary for applying genetically explicit models to predict evolution in natural populations, a necessary step for understanding the origins of mutualisms as well as their ongoing dynamics. An evolutionary genetic approach, which is focused on naturally occurring mutualist variation, can potentially synthesize the currently disconnected fields of mutualism evolution and coevolutionary genetics. We outline explanations for the maintenance of genetic variation for mutualism and suggest approaches necessary to address them. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Variation in commercial smoking mixtures containing third-generation synthetic cannabinoids.

Science.gov (United States)

Frinculescu, Anca; Lyall, Catherine L; Ramsey, John; Miserez, Bram

2017-02-01

Variation in ingredients (qualitative variation) and in quantity of active compounds (quantitative variation) in herbal smoking mixtures containing synthetic cannabinoids has been shown for older products. This can be dangerous to the user, as accurate and reproducible dosing is impossible. In this study, 69 packages containing third-generation cannabinoids of seven brands on the UK market in 2014 were analyzed both qualitatively and quantitatively for variation. When comparing the labels to actual active ingredients identified in the sample, only one brand was shown to be correctly labelled. The other six brands contained less, more, or ingredients other than those listed on the label. Only two brands were inconsistent, containing different active ingredients in different samples. Quantitative variation was assessed both within one package and between several packages. Within-package variation was within a 10% range for five of the seven brands, but two brands showed larger variation, up to 25% (Relative Standard Deviation). Variation between packages was significantly higher, with variation up to 38% and maximum concentration up to 2.7 times higher than the minimum concentration. Both qualitative and quantitative variation are common in smoking mixtures and endanger the user, as it is impossible to estimate the dose or to know the compound consumed when smoking commercial mixtures. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Epigenetic Variation May Compensate for Decreased Genetic Variation with Introductions: A Case Study Using House Sparrows (Passer domesticus on Two Continents

Directory of Open Access Journals (Sweden)

Aaron W. Schrey

2012-01-01

Full Text Available Epigenetic mechanisms impact several phenotypic traits and may be important for ecology and evolution. The introduced house sparrow (Passer domesticus exhibits extensive phenotypic variation among and within populations. We screened methylation in populations from Kenya and Florida to determine if methylation varied among populations, varied with introduction history (Kenyan invasion <50 years old, Florida invasion ~150 years old, and could potentially compensate for decrease genetic variation with introductions. While recent literature has speculated on the importance of epigenetic effects for biological invasions, this is the first such study among wild vertebrates. Methylation was more frequent in Nairobi, and outlier loci suggest that populations may be differentiated. Methylation diversity was similar between populations, in spite of known lower genetic diversity in Nairobi, which suggests that epigenetic variation may compensate for decreased genetic diversity as a source of phenotypic variation during introduction. Our results suggest that methylation differences may be common among house sparrows, but research is needed to discern whether methylation impacts phenotypic variation.

Seasonal variations of indoor radon concentrations

International Nuclear Information System (INIS)

Majborn, B.

1990-01-01

Seasonal variations of indoor radon concentrations have been studied in a cluster of 10 single-family houses. Eight of the houses are of a similar construction with slab-on-grade foundations. The remaining two houses have different substructures, one of them having a crawl space, and the other having partly a basement and partly a crawl space. A 'normal' seasonal variation of the radon concentration with a maximum in winter and a minimum in summer was observed in most of the houses. In these houses the variation showed a strong correlation with the indoor-outdoor temperature difference on a 2-month basis. However, deviating seasonal variations were observed in some of the houses, notably in the two houses having different substructures. This paper reports that a re-examination of the data obtained in a previous study indicates that winter/summer ratios of indoor radon concentrations in Danish houses depend on the house substructure. The mean winter/summer ratios were about 2.1 for houses with slab-on-grade foundations, 1.5 for houses having a basement, and 1.0 for houses with a crawl space (geometric mean values). However, a study with more houses in each substructure category will be needed to show whether or not the indicated differences are generally valid for Danish houses

Non-commuting variations in mathematics and physics a survey

CERN Document Server

Preston, Serge

2016-01-01

This text presents and studies the method of so –called noncommuting variations in Variational Calculus. This method was pioneered by Vito Volterra who noticed that the conventional Euler-Lagrange (EL-) equations are not applicable in Non-Holonomic Mechanics and suggested to modify the basic rule used in Variational Calculus. This book presents a survey of Variational Calculus with non-commutative variations and shows that most basic properties of conventional Euler-Lagrange Equations are, with some modifications, preserved for EL-equations with K-twisted (defined by K)-variations. Most of the book can be understood by readers without strong mathematical preparation (some knowledge of Differential Geometry is necessary). In order to make the text more accessible the definitions and several necessary results in Geometry are presented separately in Appendices I and II Furthermore in Appendix III a short presentation of the Noether Theorem describing the relation between the symmetries of the differential equa...

Variational principles in terms of entransy for heat transfer

International Nuclear Information System (INIS)

Xu, Mingtian

2012-01-01

A variational principle for heat conduction is formulated which results in the steady state heat conduction equation established from the Fourier law. Furthermore based on the thermodynamics in terms of entransy a more general functional is defined for incompressible fluids. We show that extremizing this functional gives rise to the state described by the Navier-Stokes-Fourier equations with vanishing substantive derivatives of the temperature and velocity field. In this sense one may conclude that this variational principle is consistent with the Navier-Stokes-Fourier equations. Therefore the variational principle developed in the present work demonstrates a great advantage over the minimum entropy production principle. -- Highlights: ► A variational principle for heat transfer of incompressible fluid is established in terms of entransy. ► For pure heat conduction the variational principle leads to the classical steady state heat conduction equation. ► For heat convection the variational principle is consistent with the Navier-Stokes-Fourier equations.

Amplitude Variations in Pulsating Red Giants. II. Some Systematics

Science.gov (United States)

Percy, J. R.; Laing, J.

2017-12-01

In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.

On the variation of the gravitational constant G

International Nuclear Information System (INIS)

De Sabbata, V.

1980-01-01

We consider the variation of the gravitational constant G starting from Dirac's large number hypothesis. After a brief description of the various gravitational theories which, other than General Relativity, incorporate the variation of G, we consider the geophysical and astrophysical consequences of the variation of G and the present status of the performed experiments. Finally, a short account on strong gravity is given which seems to provide a basis for Dirac's large number hypothesis. (author)

Utilization of gamma radiation for the induction of phenotypical variability in hybrid petunia cultivated in vitro

International Nuclear Information System (INIS)

Miranda Jimenez, Javier I.

2006-01-01

are by somaclonal variation. Also, the use of the variation found in the morphological characteristics, is discussed, in particular, the flower form, the brown of its throat and the plant architecture, for the performance of crosses and obtention of plants with better ornamental characteristics. (author) [es

Variation in important pasture grasses: I. Morphological and ...

African Journals Online (AJOL)

Variation in important pasture grasses: I. Morphological and geographical variation. ... Seven species are important pasture grasses throughout the western Transvaal, Orange Free State, northern Cape and Natal. ... Language: English.

Studies on the Colour Variation in Larvae of Ephestia kuhniella (ZELLER)(Lepidoptera, Phycitidae) : 1. On the Inheritance of colour variation

OpenAIRE

Osamu, IMURA; Entomology Laboratory, National Food Research Institute

1980-01-01

The crossing experiment and the selection experiment were carried out at 25℃ and 67% r.h. to define genetic mechanisms of the colour variation in larvae of Ephestia kuhniella. The populations sampled from the Wild-type stock showed the wide range of continuous colour variation from white to deep pink in the 5th inster lavae. The results of the crossing experiment between white larval strain and red larval strain selected from the Wild-type stock suggested the larval colour variation was a qua...

Variational coupling between q-number and c-number dynamics

International Nuclear Information System (INIS)

Amaral, C.M. do; Joffily, S.

1984-01-01

The time-dependent quantum variational principle is generalized for the case of hamiltonian operators having real parameters and their time derivates. The obtained variational system is formed by a Schroedinger equation coupled to a Lagrange equation system, where the lagrangian is the average value of the parametrized hamiltonian operator. The consequent dynamics of the variational principle, describes the interaction between a q-number sub-dynamics with a c-number sub-dynamics. In the ((h/2π)) 0 -order W.K.B. approximation, the variational system reduces to a Hamilton-Jacobi-like equation, coupled to a Lagrange equation family. The formal features of the obtained variational system are appropriated for the description of, adiabatics and non-adiabatics, time-dependent q-number c-number interactions. (L.C.) [pt

Fast magnetic resonance imaging based on high degree total variation

Science.gov (United States)

Wang, Sujie; Lu, Liangliang; Zheng, Junbao; Jiang, Mingfeng

2018-04-01

In order to eliminating the artifacts and "staircase effect" of total variation in Compressive Sensing MRI, high degree total variation model is proposed for dynamic MRI reconstruction. the high degree total variation regularization term is used as a constraint to reconstruct the magnetic resonance image, and the iterative weighted MM algorithm is proposed to solve the convex optimization problem of the reconstructed MR image model, In addtion, one set of cardiac magnetic resonance data is used to verify the proposed algorithm for MRI. The results show that the high degree total variation method has a better reconstruction effect than the total variation and the total generalized variation, which can obtain higher reconstruction SNR and better structural similarity.

Unambiguous results from variational matrix Pade approximants

International Nuclear Information System (INIS)

Pindor, Maciej.

1979-10-01

Variational Matrix Pade Approximants are studied as a nonlinear variational problem. It is shown that although a stationary value of the Schwinger functional is a stationary value of VMPA, the latter has also another stationary value. It is therefore proposed that instead of looking for a stationary point of VMPA, one minimizes some non-negative functional and then one calculates VMPA at the point where the former has the absolute minimum. This approach, which we call the Method of the Variational Gradient (MVG) gives unambiguous results and is also shown to minimize a distance between the approximate and the exact stationary values of the Schwinger functional

Variational Monte Carlo Technique

Indian Academy of Sciences (India)

Home; Journals; Resonance – Journal of Science Education; Volume 19; Issue 8. Variational Monte Carlo Technique: Ground State Energies of Quantum Mechanical Systems. Sukanta Deb. General Article Volume 19 Issue 8 August 2014 pp 713-739 ...

A systematic review of medical practice variation in OECD countries.

Science.gov (United States)

Corallo, Ashley N; Croxford, Ruth; Goodman, David C; Bryan, Elisabeth L; Srivastava, Divya; Stukel, Therese A

2014-01-01

Major variations in medical practice have been documented internationally. Variations raise questions about the quality, equity, and efficiency of resource allocation and use, and have important implications for health care and health policy. To perform a systematic review of the peer-reviewed literature on medical practice variations in OECD countries. We searched MEDLINE to find publications on medical practice variations in OECD countries published between 2000 and 2011. We present an overview of the characteristics of published studies as well as the magnitude of variations for select high impact conditions. A total of 836 studies were included. Consistent with the gray literature, there were large variations across regions, hospitals and physician practices for almost every condition and procedure studied. Many studies focused on high-impact conditions, but very few looked at the causes or outcomes of medical practice variations. While there were an overwhelming number of publications on medical practice variations the coverage was broad and not often based on a theoretical construct. Future studies should focus on conditions and procedures that are clinically important, policy relevant, resource intensive, and have high levels of public awareness. Further study of the causes and consequences of variations is important. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Super-Planckian spatial field variations and quantum gravity

Energy Technology Data Exchange (ETDEWEB)

Klaewer, Daniel; Palti, Eran [Institut für Theoretische Physik, Ruprecht-Karls-Universität,Philosophenweg 19, 69120 Heidelberg (Germany)

2017-01-20

We study scenarios where a scalar field has a spatially varying vacuum expectation value such that the total field variation is super-Planckian. We focus on the case where the scalar field controls the coupling of a U(1) gauge field, which allows us to apply the Weak Gravity Conjecture to such configurations. We show that this leads to evidence for a conjectured property of quantum gravity that as a scalar field variation in field space asymptotes to infinity there must exist an infinite tower of states whose mass decreases as an exponential function of the scalar field variation. We determine the rate at which the mass of the states reaches this exponential behaviour showing that it occurs quickly after the field variation passes the Planck scale.

Species conservation and natural variation among populations [Chapter 5

Science.gov (United States)

Leonard F. Ruggiero; Michael K. Schwartz; Keith B. Aubry; Charles J. Krebs; Amanda Stanley; Steven W. Buskirk

2000-01-01

In conservation planning, the importance of natural variation is often given inadequate consideration. However, ignoring the implications of variation within species may result in conservation strategies that jeopardize, rather than conserve, target species (see Grieg 1979; Turcek 1951; Storfer 1999). Natural variation in the traits of individuals and populations is...

Cost variation in diabetes care delivered in English hospitals

DEFF Research Database (Denmark)

Kristensen, Troels; Laudicella, Mauro; Ejersted, Charlotte

2010-01-01

are transferred between hospitals, suffer infections and other complications, or for those who die in hospital. Even so, around 8-9% of the variation in costs is related to the hospital in which the patient is treated, with geographical variation in factor prices being the prime reason for this variation...

Prostate Contouring Variation: Can It Be Fixed?

International Nuclear Information System (INIS)

Khoo, Eric L.H.; Schick, Karlissa; Plank, Ashley W.; Poulsen, Michael; Wong, Winnie W.G.; Middleton, Mark; Martin, Jarad M.

2012-01-01

Purpose: To assess whether an education program on CT and MRI prostate anatomy would reduce inter- and intraobserver prostate contouring variation among experienced radiation oncologists. Methods and Materials: Three patient CT and MRI datasets were selected. Five radiation oncologists contoured the prostate for each patient on CT first, then MRI, and again between 2 and 4 weeks later. Three education sessions were then conducted. The same contouring process was then repeated with the same datasets and oncologists. The observer variation was assessed according to changes in the ratio of the encompassing volume to intersecting volume (volume ratio [VR]), across sets of target volumes. Results: For interobserver variation, there was a 15% reduction in mean VR with CT, from 2.74 to 2.33, and a 40% reduction in mean VR with MRI, from 2.38 to 1.41 after education. A similar trend was found for intraobserver variation, with a mean VR reduction for CT and MRI of 9% (from 1.51 to 1.38) and 16% (from 1.37 to 1.15), respectively. Conclusion: A well-structured education program has reduced both inter- and intraobserver prostate contouring variations. The impact was greater on MRI than on CT. With the ongoing incorporation of new technologies into routine practice, education programs for target contouring should be incorporated as part of the continuing medical education of radiation oncologists.

Genetic Variations Involved in Vitamin E Status

Directory of Open Access Journals (Sweden)

Patrick Borel

2016-12-01

Full Text Available Vitamin E (VE is the generic term for four tocopherols and four tocotrienols that exhibit the biological activity of α-tocopherol. VE status, which is usually estimated by measuring fasting blood VE concentration, is affected by numerous factors, such as dietary VE intake, VE absorption efficiency, and VE catabolism. Several of these factors are in turn modulated by genetic variations in genes encoding proteins involved in these factors. To identify these genetic variations, two strategies have been used: genome-wide association studies and candidate gene association studies. Each of these strategies has its advantages and its drawbacks, nevertheless they have allowed us to identify a list of single nucleotide polymorphisms associated with fasting blood VE concentration and α-tocopherol bioavailability. However, much work remains to be done to identify, and to replicate in different populations, all the single nucleotide polymorphisms involved, to assess the possible involvement of other kind of genetic variations, e.g., copy number variants and epigenetic modifications, in order to establish a reliable list of genetic variations that will allow us to predict the VE status of an individual by knowing their genotype in these genetic variations. Yet, the potential usefulness of this area of research is exciting with regard to personalized nutrition and for future clinical trials dedicated to assessing the biological effects of the various isoforms of VE.

Factors affecting yearly variations of indoor radon concentrations

International Nuclear Information System (INIS)

Steck, D.J.; Baynes, S.A.

1996-01-01

Since indoor radon exposures take place over many years while radon measurement periods are shorter, we are studying the yearly variation of indoor radon concentrations in approximately 100 houses located throughout Minnesota. Most houses were initially measured for one or more years in the late 1980's and for 5 consecutive years starting in 1990. Two houses have been monitored for 12 y. Each year, two alpha track detectors were placed on the two lowest livable levels. The year-to-year variations averaged about 35% (corrected for instrumental uncertainties) in both basements and first floors. The minimum observed variation was 5% and the maximum was 130%. Some homes have shown substantial variation associated with Structural modifications. While most homes show no obvious systematic trends, a few houses have shown temporal trends that may be associated with aging or climate. We are studying possible correlation between year-to-year radon variation, climatic variables (yearly-average and seasonal such as heating/cooling degree days, precipitation, soil moisture), and structural changes

Within-Individual Variation in Preferences Equity Effects of Congestion Charges

DEFF Research Database (Denmark)

Borjesson, Maria; Cherchi, Elisabetta; Bierlaire, Michel

2013-01-01

in VTT arising from income differences was found to be substantially smaller than the variation in VTT between trips. Moreover, the variability in VTT averaged over all trips within each individual was considerably smaller than the variability in VTT for all observed trips. Therefore, the assumption...... that variation in VTT between observed trips reflects the variation in the average VTT between individuals, which is usually made in equity analyses, will over-state the between-individual variation. The results suggest that if intraindividual variation in preferences is not taken into account, the negative...

Biological variation of cystatin C

DEFF Research Database (Denmark)

Reinhard, Mark; Erlandsen, Erland; Randers, Else

2009-01-01

Introduction: Cystatin C has been investigated as a marker of the glomerular filtration rate. However, previous studies have reported conflicting results concerning the biological variation of cystatin C. The aim of the present study was to evaluate the biological variation of cystatin C...... in comparison to creatinine. Methods: Eight weekly morning blood samples were taken from twenty healthy volunteers (13 females, 7 males) aged 25-61 years. Mean creatinine clearance was 99.7 ml/min/1.73 m2 (range 61.8-139.5) and mean body mass index 23.9 kg/m2 (range 20.3-28.7). A total of 155 samples were...

Structure variations of carbonizing lignin

International Nuclear Information System (INIS)

Otani, C.; Polidoro, H.A.; Otani, S.; Craievich, A.F.

1984-01-01

The studied lignin is a by-product of the process of ethanol production from eucaliptus. It was heat-treated under inert atmosphere conditions at increasing temperatures from 300C up to 2400C. The structural variations were studied by wide-angle X-ray diffraction, small-angle X-ray scattering and infrared absorption spectroscopy. The bulk and 'real' density of the compacted materials have also been determined as functions of the final temperature. These experimental results enabled us to establish a mechanism of structure variation based on the formation of a turbostratic graphite-like and porous structure within the initially amorphous lignin matrix. (Author) [pt

Hospital Variation in Cesarean Delivery: A Multilevel Analysis.

Science.gov (United States)

Vecino-Ortiz, Andres I; Bardey, David; Castano-Yepes, Ramon

2015-12-01

To assess the issue of hospital variations in Colombia and to contribute to the methodology on health care variations by using a model that clusters the variance between hospitals while accounting for individual-level reimbursement rates and objective health-status variables. We used data on all births (N = 11,954) taking place in a contributory-regimen insurer network in Colombia during 2007. A multilevel logistic regression model was used to account for the share of unexplained variance between hospitals. In addition, an alternative variance decomposition specification was further carried out to measure the proportion of such unexplained variance due to the region effect. Hospitals account for 20% of the variation in performing cesarean sections, whereas region explains only one-third of such variance. Variables accounting for preferences on the demand side as well as reimbursement rates are found to predict the probability of performing cesarean sections. Hospital variations explain large variances within a single-payer's network. Because this insurer company is highly regarded in terms of performance and finance, these results might provide a lower bound for the scale of hospital variation in the Colombian health care market. Such lower bound provides guidance on the relevance of this issue for Colombia. Some factors such as demand-side preferences and physician reimbursement rates increase variations in health care even within a single-payer network. This is a source of inefficiencies, threatening the quality of health care and financial sustainability. The proposed methodology should be considered in further research on health care variations. Copyright © 2015 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Short-term variations of radiocarbon during the last century

International Nuclear Information System (INIS)

Burchuladze, A.A.; Pagava, S.V.; Jurina, V.; Povinec, P.; Usacev, S.

1982-01-01

Radiocarbon variations related to the 11-year solar cycle during the last century are discussed. Previous investigations on short term 14 C variations in tree rings are compared with 14 C measurements in Georgian wine samples. The amplitude of 14 C variations as obtained by various authors ranges from 0.2 to about 1%. (author)

Geographic variation in expenditures for Workers' Compensation hospitalized claims.

Science.gov (United States)

Miller, T R; Levy, D T

1999-02-01

Past literature finds considerable variation in the cost of physician care and in the utilization of medical procedures. Variation in the cost of hospitalized care has received little attention. We examine injury costs of hospitalized claims across states. Multivariate regression analysis is used to isolate state variations, while controlling for personal and injury characteristics, and state characteristics. Injuries to workers filing Workers' Compensation lost workday claims. About 35,000 randomly sampled Workers' Compensation claims from 17 states filed between 1979 and 1988. Medical payments per episode of three injury groups: upper and lower extremity fractures and dislocations, other upper extremity injuries, and back strains and sprains. Statistical analyses reveal considerable variation in expenditures for hospitalized injuries across states, even after controlling for case mix and state characteristics. A substantial portion of the variation is explained by state rate regulations; regulated states have lower costs. The large variation in costs suggests a potential to affect the costs of hospitalized care. Efforts should be directed at those areas that have higher costs without sufficient input price, quality, or case mix justification.

Genetic variation in natural honeybee populations, Apis mellifera capensis

Science.gov (United States)

Hepburn, Randall; Neumann, Peter; Radloff, Sarah E.

2004-09-01

Genetic variation in honeybee, Apis mellifera, populations can be considerably influenced by breeding and commercial introductions, especially in areas with abundant beekeeping. However, in southern Africa apiculture is based on the capture of wild swarms, and queen rearing is virtually absent. Moreover, the introduction of European subspecies constantly failed in the Cape region. We therefore hypothesize a low human impact on genetic variation in populations of Cape honeybees, Apis mellifera capensis. A novel solution to studying genetic variation in honeybee populations based on thelytokous worker reproduction is applied to test this hypothesis. Environmental effects on metrical morphological characters of the phenotype are separated to obtain a genetic residual component. The genetic residuals are then re-calculated as coefficients of genetic variation. Characters measured included hair length on the abdomen, width and length of wax plate, and three wing angles. The data show for the first time that genetic variation in Cape honeybee populations is independent of beekeeping density and probably reflects naturally occurring processes such as gene flow due to topographic and climatic variation on a microscale.

Variational field theoretic approach to relativistiv meson-nucleon scattering

International Nuclear Information System (INIS)

Alexandrou, C.; Rosenfelder, R.; Schreiber, A.W.; TRIUMF, Vancouver, BC; Adelaide Univ., SA; Adelaide Univ., SA; Univ. Adelaide

1998-01-01

Non-perturbative polaron variational methods are applied, within the so-called particle or worldline representation of relativistic field theory, to study scattering in the context of the scalar Wick-Cutkosky model. Important features of the variational calculation are that it is a controlled approximation scheme valid for arbitrary coupling strengths, the Green functions have all the cuts and poles expected for the exact result at any order in perturbation theory and that the variational parameters are simultaneously sensitive to the infrared as well as the ultraviolet behaviour of the theory. We generalize the previously used quadratic trial action by allowing more freedom for off-shell propagation without a change in the on-shell variational equations and evaluate the scattering amplitude at first order in the variational scheme. Particular attention is paid to the s-channel scattering near threshold because here non-perturbative effects can be large. We check the unitarity of a our numerical calculation and find it greatly improved compared to perturbation theory and to the zeroth order variational results. (orig.)

Comparative analysis of face recognition techniques with illumination variation

International Nuclear Information System (INIS)

Jondhale, K C; Waghmare, L M

2010-01-01

Illumination variation is one of the major challenges in the face recognition. To deal with this problem, this paper presents comparative analysis of three different techniques. First, the DCT is employed to compensate for illumination variations in the logarithm domain. Since illumination variation lies mainly in the low frequency band, an appropriate number of DCT coefficients are truncated to reduce the variations under different lighting conditions. The nearest neighbor classifier based on Euclidean distance is employed for classification. Second, the performance of PCA is checked on normalized image. PCA is a technique used to reduce multidimensional data sets to a lower dimension for analysis. Third, LDA based methods gives a satisfactory result under controlled lighting condition. But its performance under large illumination variation is not satisfactory. So, the performance of LDA is checked on normalized image. Experimental results on the Yale B and ORL database show that the proposed approach of application of PCA and LDA on normalized dataset improves the performance significantly for the face images with large illumination variations.

Robust design principles for reducing variation in functional performance

DEFF Research Database (Denmark)

Christensen, Martin Ebro; Howard, Thomas J.

2016-01-01

This paper identifies, describes and classifies a comprehensive collection of variation reduction principles (VRP) that can be used to increase the robustness of a product and reduce its variation in functional performance. Performance variation has a negative effect on the reliability and percei......This paper identifies, describes and classifies a comprehensive collection of variation reduction principles (VRP) that can be used to increase the robustness of a product and reduce its variation in functional performance. Performance variation has a negative effect on the reliability...... and perceived quality of a product and efforts should be made to minimise it. The design principles are identified by a systematic decomposition of the Taguchi Transfer Function in combination with the use of existing literature and the authors’ experience. The paper presents 15 principles and describes...... their advantages and disadvantages along with example cases. Subsequently, the principles are classified based on their applicability in the various development and production stages. The VRP are to be added to existing robust design methodologies, helping the designer to think beyond robust design tool and method...

Anatomy, Medical Education, and Human Ancestral Variation

Science.gov (United States)

Strkalj, Goran; Spocter, Muhammad A.; Wilkinson, A. Tracey

2011-01-01

It is argued in this article that the human body both in health and disease cannot be fully understood without adequately accounting for the different levels of human variation. The article focuses on variation due to ancestry, arguing that the inclusion of information pertaining to ancestry in human anatomy teaching materials and courses should…

Cultural Variation in Implicit Mental Illness Stigma.

Science.gov (United States)

Cheon, Bobby K; Chiao, Joan Y

2012-10-01

Culture shapes how individuals perceive and respond to others with mental illness. Prior studies have suggested that Asians and Asian Americans typically endorse greater stigma of mental illness compared to Westerners (White Europeans and Americans). However, whether these differences in stigma arise from cultural variations in automatic affective reactions or deliberative concerns of the appropriateness of one's reactions to mental illness remains unknown. Here we compared implicit and explicit attitudes toward mental illness among Asian and Caucasian Americans. Asian Americans showed stronger negative implicit attitudes toward mental illness relative to Caucasian Americans, suggesting that cultural variation in stigma of mental illness can be observed even when concerns regarding the validity and appropriateness of one's attitudes toward mental illness are minimized. Asian Americans also explicitly endorsed greater desire for social distance from mental illness relative to Caucasian Americans. These findings suggest that cultural variations in mental illness stigma may arise from cultural differences in automatic reactions to mental illness, though cultural variations in deliberative processing may further shape differences in these immediate reactions to mental illness.

Causal Genetic Variation Underlying Metabolome Differences.

Science.gov (United States)

Swain-Lenz, Devjanee; Nikolskiy, Igor; Cheng, Jiye; Sudarsanam, Priya; Nayler, Darcy; Staller, Max V; Cohen, Barak A

2017-08-01

An ongoing challenge in biology is to predict the phenotypes of individuals from their genotypes. Genetic variants that cause disease often change an individual's total metabolite profile, or metabolome. In light of our extensive knowledge of metabolic pathways, genetic variants that alter the metabolome may help predict novel phenotypes. To link genetic variants to changes in the metabolome, we studied natural variation in the yeast Saccharomyces cerevisiae We used an untargeted mass spectrometry method to identify dozens of metabolite Quantitative Trait Loci (mQTL), genomic regions containing genetic variation that control differences in metabolite levels between individuals. We mapped differences in urea cycle metabolites to genetic variation in specific genes known to regulate amino acid biosynthesis. Our functional assays reveal that genetic variation in two genes, AUA1 and ARG81 , cause the differences in the abundance of several urea cycle metabolites. Based on knowledge of the urea cycle, we predicted and then validated a new phenotype: sensitivity to a particular class of amino acid isomers. Our results are a proof-of-concept that untargeted mass spectrometry can reveal links between natural genetic variants and metabolome diversity. The interpretability of our results demonstrates the promise of using genetic variants underlying natural differences in the metabolome to predict novel phenotypes from genotype. Copyright © 2017 by the Genetics Society of America.

Solar wind velocity and geomagnetic moment variations

International Nuclear Information System (INIS)

Kalinin, Yu.D.; Rozanova, T.S.

1982-01-01

The mean year values of the solar wind velocity have been calculated from the mean-year values of a geomagnetic activity index am according to the Svalgard equation of regression for the pe-- riod from 1930 to 1960. For the same years the values of the geomagnetic moment M and separately of its ''inner'' (causes of which'' are inside the Earth) and ''external'' (causes of which are outside the Earth) parts have been calculated from the mean year data of 12 magnetic observatories. The proof of the presence of the 11-year variation in the moment M has been obtained. It is concluded that the 11-year variations in M result from the variations of the solar wind velocity

A study of variational inequalities for set-valued mappings

OpenAIRE

Tarafdar Enayet; Yuan George Xian-Zhi; Tan Kok-Keong

1999-01-01

In this paper, Ky Fan's KKM mapping principle is used to establish the existence of solutions for simultaneous variational inequalities. By applying our earlier results together with Fan–Glicksberg fixed point theorem, we prove some existence results for implicit variational inequalities and implicit quasi-variational inequalities for set-valued mappings which are either monotone or upper semi-continuous.

Determinants of intra-specific variation in basal metabolic rate.

Science.gov (United States)

Konarzewski, Marek; Książek, Aneta

2013-01-01

Basal metabolic rate (BMR) provides a widely accepted benchmark of metabolic expenditure for endotherms under laboratory and natural conditions. While most studies examining BMR have concentrated on inter-specific variation, relatively less attention has been paid to the determinants of within-species variation. Even fewer studies have analysed the determinants of within-species BMR variation corrected for the strong influence of body mass by appropriate means (e.g. ANCOVA). Here, we review recent advancements in studies on the quantitative genetics of BMR and organ mass variation, along with their molecular genetics. Next, we decompose BMR variation at the organ, tissue and molecular level. We conclude that within-species variation in BMR and its components have a clear genetic signature, and are functionally linked to key metabolic process at all levels of biological organization. We highlight the need to integrate molecular genetics with conventional metabolic field studies to reveal the adaptive significance of metabolic variation. Since comparing gene expressions inter-specifically is problematic, within-species studies are more likely to inform us about the genetic underpinnings of BMR. We also urge for better integration of animal and medical research on BMR; the latter is quickly advancing thanks to the application of imaging technologies and 'omics' studies. We also suggest that much insight on the biochemical and molecular underpinnings of BMR variation can be gained from integrating studies on the mammalian target of rapamycin (mTOR), which appears to be the major regulatory pathway influencing the key molecular components of BMR.

Arterial variations of upper limb: a case report

Directory of Open Access Journals (Sweden)

Vollala V

2005-01-01

Full Text Available Variations of upper limb arteries are common and there are many reports about this subject. We report multiple variations in arterial pattern of upper extremity, which were encountered in a single cadaver.

Metaleptic Variations

OpenAIRE

Pernot, Dominique

2014-01-01

Les derniers romans de Gabriel Josipovici offrent beaucoup de variété, allant de la parodie, de la fiction comique légère, dans Only Joking et Making Mistakes, à des sujets plus graves, plus personnels, ontologiques. Dans un court roman, Everything Passes, et dans un roman majeur, Goldberg: Variations, le lecteur est amené à se poser des questions sur la nature mystérieuse de la réalité, qui est, trop souvent, acceptée sans conteste par de nombreux roma...

Stroke volume variation compared with pulse pressure variation and cardiac index changes for prediction of fluid responsiveness in mechanically ventilated patients

Directory of Open Access Journals (Sweden)

Randa Aly Soliman

2015-04-01

Conclusions: Baseline stroke volume variation ⩾8.15% predicted fluid responsiveness in mechanically ventilated patients with acute circulatory failure. The study also confirmed the ability of pulse pressure variation to predict fluid responsiveness.

Pulse-to-pulse variations in accreting X-ray pulsars

Directory of Open Access Journals (Sweden)

Kretschmar Peter

2014-01-01

Full Text Available In most accreting X-ray pulsars, the periodic signal is very clear and easily shows up as soon as data covering sufficient pulse periods (a few ten are available. The mean pulse profile is often quite typical for a given source and with minor variations repeated and recognisable across observations done years or even decades apart. At the time scale of individual pulses, significant pulse-to-pulse variations are commonly observed. While at low energies some of these variations might be explained by absorption, in the hard X-rays they will reflect changes in the accretion and subsequent emission. The amount of these variations appears to be quite different between sources and contains information about the surrounding material as well ass possibly interactions at the magnetosphere. We investigate such variations for a sample of well-known sources.

Variation in decision making

NARCIS (Netherlands)

Dall, Sasha R. X.; Gosling, Samuel; Gordon D.A., Brown,; Dingemanse, Niels; Ido, Erev,; Martin, Kocher,; Laura, Schulz,; Todd, Peter M; Weissing, Franz; Wolf, Max; Hammerstein, Peter; Stevens, Jeffrey R.

2012-01-01

Variation in how organisms allocate their behavior over their lifetimes is key to determining Darwinian fitness., and thus the evolution of human and nonhuman decision making. This chapter explores how decision making varies across biologically and societally significant scales and what role such

Seismic noise level variation in South Korea

Science.gov (United States)

Sheen, D.; Shin, J.

2008-12-01

The variations of seismic background noise in South Korea have been investigated by means of power spectral analysis. The Korea Institute of Geoscience and Mineral Resources (KIGAM) and the Korea Meteorological Administation (KMA) have national wide seismic networks in South Korea, and, in the end of 2007, there are 30 broadband stations which have been operating for more than a year. In this study, we have estimated the power spectral density of seismic noise for 30 broadband stations from 2005 to 2007. Since we estimate PSDs from a large dataset of continuous waveform in this study, a robust PSD estimate of McNamara and Buland (2004) is used. In the frequency range 1-5 Hz, the diurnal variations of noise are observed at most of stations, which are especially larger at coastal stations and at insular than at inland. Some stations shows daily difference of diurnal variations, which represents that cultural activities contribute to the noise level of a station. The variation of number of triggered stations, however, shows that cultural noise has little influence on the detection capability of seismic network in South Korea. Seasonal variations are observed well in the range 0.1-0.5 Hz, while much less found in the frequency range 1-5 Hz. We observed that strong peaks in the range 0.1-0.5 Hz occur at the summer when Pacific typhoons are close to the Korean Peninsula.

Period Variations for the Cepheid VZ Cyg

Science.gov (United States)

Sirorattanakul, Krittanon; Engle, Scott; Pepper, Joshua; Wells, Mark; Laney, Clifton D.; Rodriguez, Joseph E.; Stassun, Keivan G.

2017-12-01

The Cepheid Period-Luminosity law is a key rung on the extragalactic distance ladder. However, numerous Cepheids are known to undergo period variations. Monitoring, refining, and understanding these period variations allows us to better determine the parameters of the Cepheids themselves and of the instability strip in which they reside, and to test models of stellar evolution. VZ Cyg, a classical Cepheid pulsating at ˜4.864 days, has been observed for over 100 years. Combining data from literature observations, the Kilodegree Extremely Little Telescope (KELT) transit survey, and new targeted observations with the Robotically Controlled Telescope (RCT) at Kitt Peak, we find a period change rate of dP/dt = -0.0642 ± 0.0018 s yr-1. However, when only the recent observations are examined, we find a much higher period change rate of dP/dt = -0.0923 ± 0.0110 s yr-1. This higher rate could be due to an apparent long-term (P ≈ 26.5 years) cyclic period variation. The possible interpretations of this single Cepheid’s complex period variations underscore both the need to regularly monitor pulsating variables and the important benefits that photometric surveys such as KELT can have on the field. Further monitoring of this interesting example of Cepheid variability is recommended to confirm and better understand the possible cyclic period variations. Further, Cepheid timing analyses are necessary to fully understand their current behaviors and parameters, as well as their evolutionary histories.

Total Variation Depth for Functional Data

KAUST Repository

Huang, Huang

2016-11-15

There has been extensive work on data depth-based methods for robust multivariate data analysis. Recent developments have moved to infinite-dimensional objects such as functional data. In this work, we propose a new notion of depth, the total variation depth, for functional data. As a measure of depth, its properties are studied theoretically, and the associated outlier detection performance is investigated through simulations. Compared to magnitude outliers, shape outliers are often masked among the rest of samples and harder to identify. We show that the proposed total variation depth has many desirable features and is well suited for outlier detection. In particular, we propose to decompose the total variation depth into two components that are associated with shape and magnitude outlyingness, respectively. This decomposition allows us to develop an effective procedure for outlier detection and useful visualization tools, while naturally accounting for the correlation in functional data. Finally, the proposed methodology is demonstrated using real datasets of curves, images, and video frames.

Lunar nitrogen: Secular variation or mixing?

International Nuclear Information System (INIS)

Norris, S.J.; Wright, I.P.; Pillinger, C.T.

1986-01-01

The two current models to explain the nearly 40% variation of the lunar nitrogen isotopic composition are: (1) secular variation of solar wind nitrogen; and (2) a two component mixing model having a constant, heavy solar wind admixed with varying amounts of indigenous light lunar N (LLN). Both models are needed to explain the step pyrolysis extraction profile. The secular variation model proposes that the low temperature release is modern day solar wind implanted into grain surfaces, the 900 C to 1100 C release is from grain surfaces which were once exposed to the ancient solar wind but which are now trapped inside agglutinates, and the >1100 C release as spallogenic N produced by cosmic rays. The mixing model ascribes the components to solar wind, indigenous lunar N and spallogenic N respectively. An extension of either interpretation is that the light N seen in lunar breccias or deep drill cores represent conditions when more N-14 was available to the lunar surface

Variational Integrals of a Class of Nonhomogeneous -Harmonic Equations

Directory of Open Access Journals (Sweden)

Guanfeng Li

2014-01-01

Full Text Available We introduce a class of variational integrals whose Euler equations are nonhomogeneous -harmonic equations. We investigate the relationship between the minimization problem and the Euler equation and give a simple proof of the existence of some nonhomogeneous -harmonic equations by applying direct methods of the calculus of variations. Besides, we establish some interesting results on variational integrals.

A study of variational inequalities for set-valued mappings

Directory of Open Access Journals (Sweden)

Tarafdar Enayet

1999-01-01

Full Text Available In this paper, Ky Fan's KKM mapping principle is used to establish the existence of solutions for simultaneous variational inequalities. By applying our earlier results together with Fan–Glicksberg fixed point theorem, we prove some existence results for implicit variational inequalities and implicit quasi-variational inequalities for set-valued mappings which are either monotone or upper semi-continuous.

Evaluation of a new paleosecular variation activity index as a diagnostic tool for geomagnetic field variations

Science.gov (United States)

Panovska, Sanja; Constable, Catherine

2015-04-01

Geomagnetic indices like Dst, K and A, have been used since the early twentieth century to characterize activity in the external part of the modern geomagnetic field and as a diagnostic for space weather. These indices reflect regional and global activity and serve as a proxy for associated physical processes. However, no such tools are yet available for the internal geomagnetic field driven by the geodynamo in Earth's liquid outer core. To some extent this reflects limited spatial and temporal sampling for longer timescales associated with paleomagnetic secular variation, but recent efforts in both paleomagnetic data gathering and modeling activity suggest that longer term characterization of the internal geomagnetic weather/climate and its variability would be useful. Specifically, we propose an index for activity in paleosecular variation, useful as both a local and global measure of field stability during so-called normal secular variation and as a means of identifying more extreme behavior associated with geomagnetic excursions and reversals. To date, geomagnetic excursions have been identified by virtual geomagnetic poles (VGPs) deviating more than some conventional limit from the geographic pole (often 45 degrees), and/or by periods of significant intensity drops below some critical value, for example 50% of the present-day field. We seek to establish a quantitative definition of excursions in paleomagnetic records by searching for synchronous directional deviations and lows in relative paleointensity. We combine paleointensity variations with deviations from the expected geocentric axial dipole (GAD) inclination in a single parameter, which we call the paleosecular variation (PSV) activity index. This new diagnostic can be used on any geomagnetic time series (individual data records, model predictions, spherical harmonic coefficients, etc.) to characterize the level of paleosecular variation activity, find excursions, or even study incipient reversals

Reference free phasing and representation of complex variation

DEFF Research Database (Denmark)

Jensen, Jacob Malte

2017-01-01

High throughput sequencing has revolutionized our ability to interrogate genomes and entire human genomes are sequenced daily across the world. Mapping of short reads to a reference genome has enhanced our ability to detect genetic variation and is currently the most widely used technology....... Therefore, new methods for detecting variation that reduce reference bias are needed including ways of representing genomes that account for the variability within and between populations. The major histocompatibility complex (MHC) region is one of the most diverse and complex regions of the human genome...... to detect and call variation in humans. However, it has become evident that mapping of short reads to a single reference genome is subject to ascertainment bias (reference bias). This bias is especially pronounced in complex regions of the genome and particularly hampers detection of structural variation...

Spanwise drag variation on low Re wings -- revisited

Science.gov (United States)

Yang, Shanling; Spedding, Geoffrey

2011-11-01

Aerodynamic performance measurement and prediction of airfoils and wings at chord Reynolds numbers below 105 is both difficult and increasingly important in application to small-scale aircraft. Not only are the aerodynamics strongly affected by the dynamics of the unstable laminar boundary layer but the flow is decreasingly likely to be two-dimensional as Re decreases. The spanwise variation of the flow along a two-dimensional geometry is often held to be responsible for the large variations in measured profile drag coefficient. Here we measure local two-dimensional drag coefficients along a finite wing using non-intrusive PIV methods. Variations in Cd (y) can be related to local flow variations on the wing itself. Integrated values can be compared with force balance data, and the proper description of drag components at low Re will be discussed.

Gravity Variations Related to Earthquakes in the BTTZ Region in China

Science.gov (United States)

Zheng, J.; Liu, K.; Lu, H.; Liu, D.; Chen, Y.; Kuo, J. T.

2006-05-01

Temporal variations of gravity before and after earthquakes have been observed since 1960s, but a definitive conclusion has not been reached concerning the relationship between the gravity variation and earthquake occurrence. Since 1980, the first US/China joint scientific research project has been monitoring micro-gravity variations related to earthquakes in the Beijing-Tianjin-Tangshan-Zhangjiekou (BTTZ) region in China through the establishment of a network of spatially and temporally continuous and discrete gravity stations. With the data of both temporally continuous and discrete data of gravity variations accumulated and analyzed, a general picture of gravity variation associated with the seismogenesis and occurrence of earthquakes in the BTTZ region has been emerged clearly. Some of the major findings are 1. Gravity variations before and after earthquakes exist spatially and temporally; 2. Gravity variation data of temporally continuous measurements are essential to monitor the variations of gravity related to earthquakes unless temporally discrete gravity data are made in very close time intervals. 3. Concept of epicentroid and hypocentroid with respect to the maximum values of gravity variation is valid and has been experimentally verified; 4. The gravity variations related to the occurrence of earthquakes in the BTTZ region for the magnitudes of 4-5 earthquakes support the proposed "combined dilatation model", i.e., a dual-dilatancy of diffusion dilatancy (D/D) and the fault zone dilatancy (FZD) models; 5. Although the temporally discrete gravity variation data were collected in a larger time interval of about six months in the BTTZ region, these gravity variation data, in some cases, indicate that these variations are related to the occurrence of earthquakes; 7. Subsurface fluids do play a very important role in the gravity variations that have not been recognized and emphasized previously; 7. With the temporally continuous gravity variation data, the

Anatomical Variations of the Circulus Arteriosus in Cadaveric Human Brains

Science.gov (United States)

Gunnal, S. A.; Farooqui, M. S.; Wabale, R. N.

2014-01-01

Objective. Circulus arteriosus/circle of Willis (CW) is a polygonal anastomotic channel at the base of the brain which unites the internal carotid and vertebrobasilar system. It maintains the steady and constant supply to the brain. The variations of CW are seen often. The Aim of the present work is to find out the percentage of normal pattern of CW, and the frequency of variations of the CW and to study the morphological and morphometric aspects of all components of CW. Methods. Circulus arteriosus of 150 formalin preserved brains were dissected. Dimensions of all the components forming circles were measured. Variations of all the segments were noted and well photographed. The variations such as aplasia, hypoplasia, duplication, fenestrations, and difference in dimensions with opposite segments were noted. The data collected in the study was analyzed. Results. Twenty-one different types of CW were found in the present study. Normal and complete CW was found in 60%. CW with gross morphological variations was seen in 40%. Maximum variations were seen in the PCoA followed by the ACoA in 50% and 40%, respectively. Conclusion. As it confirms high percentage of variations, all surgical interventions should be preceded by angiography. Awareness of these anatomical variations is important in neurovascular procedures. PMID:24891951

Individual Variation in Life History Characteristics Can Influence Extinction Risk

Energy Technology Data Exchange (ETDEWEB)

Jager, H I

2001-01-01

The white sturgeon (Acipenser transmontanus) shows great individual variation in the age at maturation. This study examines the consequences of model assumptions about individual variation in the age at maturation on predicted population viability. I considered: (1) the effects of variation in age at maturation alone; (2) the effects of heritability; and (3) the influence of a stable and an altered selective regime. Two selective regimes represented conditions before and after the impoundment of a river, blocking access of anadromous white sturgeon populations to the ocean. In contrast to previous simulation studies, I found that increased individual variation in the age at maturity did not necessarily lead to a higher likelihood of persistence. Individual variation increased the simulated likelihood of persistence when the variation was heritable and the selective regime had changed such that the mean age at maturity was no longer optimal.

Approximate variational solutions of the Grad-Shafranov equation

International Nuclear Information System (INIS)

Ludwig, G.O.

2001-01-01

Approximate solutions of the Grad-Schlueter-Shafranov equation based on variational methods are developed. The power series solutions of the Euler-Lagrange equations for equilibrium are compared with direct variational results for a low aspect ratio tokamak equilibrium. (author)

Quantitative variation in natural populations

International Nuclear Information System (INIS)

Parsons, P.A.

1975-01-01

Quantitative variation is considered in natural populations using Drosophila as the example. A knowledge of such variation enables its rapid exploitation in directional selection experiments as shown for scutellar chaeta number. Where evidence has been obtained, genetic architectures are in qualitative agreement with Mather's concept of balance for traits under stabilizing selection. Additive genetic control is found for acute environmental stresses, but not for less acute stresses as shown by exposure to 60 Co-γ rays. D. simulans probably has a narrower ecological niche than its sibling species D. melanogaster associated with lower genetic heterogeneity. One specific environmental stress to which D. simulans is sensitive in nature is ethyl alcohol as shown by winery data. (U.S.)

Coarse Grained Exponential Variational Autoencoders

KAUST Repository

Sun, Ke

2017-02-25

Variational autoencoders (VAE) often use Gaussian or category distribution to model the inference process. This puts a limit on variational learning because this simplified assumption does not match the true posterior distribution, which is usually much more sophisticated. To break this limitation and apply arbitrary parametric distribution during inference, this paper derives a \\\\emph{semi-continuous} latent representation, which approximates a continuous density up to a prescribed precision, and is much easier to analyze than its continuous counterpart because it is fundamentally discrete. We showcase the proposition by applying polynomial exponential family distributions as the posterior, which are universal probability density function generators. Our experimental results show consistent improvements over commonly used VAE models.

(Ln-bar, g)-spaces. Variation operator

International Nuclear Information System (INIS)

Manoff, S.; Dimitrov, B.

1998-01-01

A variation operator is determined over (L n bar, g)-spaces as a linear differential operator, acting on tensor fields in a given basis. Its commutation relations with the Lie differential operator, with the covariant differential operator and with the contraction operator are imposed. The corollaries from using the different commutation relations in a Lagrangian formalism are found and two types of variation methods are distinguished: the common (canonical) method of Lagrangians with partial derivatives (MLPD) and the method of Lagrangians with covariant derivatives (MLCD)

Hybrid Steepest-Descent Methods for Triple Hierarchical Variational Inequalities

Directory of Open Access Journals (Sweden)

L. C. Ceng

2015-01-01

Full Text Available We introduce and analyze a relaxed iterative algorithm by combining Korpelevich’s extragradient method, hybrid steepest-descent method, and Mann’s iteration method. We prove that, under appropriate assumptions, the proposed algorithm converges strongly to a common element of the fixed point set of infinitely many nonexpansive mappings, the solution set of finitely many generalized mixed equilibrium problems (GMEPs, the solution set of finitely many variational inclusions, and the solution set of general system of variational inequalities (GSVI, which is just a unique solution of a triple hierarchical variational inequality (THVI in a real Hilbert space. In addition, we also consider the application of the proposed algorithm for solving a hierarchical variational inequality problem with constraints of finitely many GMEPs, finitely many variational inclusions, and the GSVI. The results obtained in this paper improve and extend the corresponding results announced by many others.

Multidimensional analysis of Drosophila wing variation in Evolution ...

Indian Academy of Sciences (India)

2008-12-23

Dec 23, 2008 ... the different components of phenotypic variation of a complex trait: the wing. ... of Drosophila wing variation in. Evolution Canyon. J. Genet. 87, 407–419]. Introduction ..... identify the effect of slope on wing shape (figure 2,c). All.

A variational void coalescence model for ductile metals

KAUST Repository

Siddiq, Amir; Arciniega, Roman; El Sayed, Tamer

2011-01-01

We present a variational void coalescence model that includes all the essential ingredients of failure in ductile porous metals. The model is an extension of the variational void growth model by Weinberg et al. (Comput Mech 37:142-152, 2006

Assessment of clonal fidelity of Tylophora indica (Burm. f.) Merrill "in vitro" plantlets by ISSR molecular markers.

Science.gov (United States)

Sharma, Madan Mohan; Verma, Roop Narayan; Singh, Abhijeet; Batra, Amla

2014-01-01

Tylophora indica Burm F. Merrill. is widely used against various diseases owing to the presence an array of medicinally important secondary metabolites. Its stem is bitter, stomachic, stimulates bile secretion, enriches the blood and cures diseases like diabetes, fever, flatulence, hypertension, jaundice, leucorrhoea, urinary disease and upper respiratory tract infection. It is neglected for tissue culture work because of deciduous nature of climbing shrub, facing problems for micropropagation. Hence, in vitro regeneration of complete plantlets was done through indirect organogenesis in Tylophora indica. Calli were produced from in vivo leaves of T. indica on MS medium supplemented with 6-Benzylaminopurine (BAP: 2.0 mg l(-1)) and Indole-3-butyric acid (IBA: 0.5 mg l(-1)). The multiple shoots (12.00 ± 1.50) emerged and elongated on MS medium fortified with Thidiazuron (TDZ: 0.1 mg l(-1)). They were rooted on half strength MS medium having IBA (0.5 mg l(-1)) (7.75 ± 0.25) after 20 days of sub-culturing followed by hardening and acclimatization. During indirect regeneration of plants, chances of somaclonal variations may arise. These variations should be identified to produce true to type plants. Plantlets raised through tissue culture were used to validate the clonal fidelity through Inter simple sequence repeat markers (ISSR). Clonal fidelity is a major consideration in commercial micropropagation using in vitro tissue culture methods. During the study, total 71 clear and distinct bands were produced using 6 primers. The banding pattern of each primer was uniform and comparable to mother plant and showed about 93% homology using un-weighted pair group method with arithmetic averaging (UPGMA). ISSR analysis confirmed the genetic stability of in vitro raised plants.

Micropropagation of transgenic lettuce containing HBsAg as a method of mass-scale production of standardised plant material for biofarming purposes.

Science.gov (United States)

Pniewski, Tomasz; Czyż, Marcin; Wyrwa, Katarzyna; Bociąg, Piotr; Krajewski, Paweł; Kapusta, Józef

2017-01-01

Micropropagation protocol of transgenic lettuce bearing S-, M- and L-HBsAg was developed for increased production of uniformised material for oral vaccine preparation. Effective manufacturing of plant-based biopharmaceuticals, including oral vaccines, depends on sufficient content of a protein of interest in the initial material and its efficient conversion into an administrable formulation. However, stable production of plants with a uniformised antigen content is equally important for reproducible processing. This can be provided by micropropagation techniques. Here, we present a protocol for micropropagation of transgenic lettuce lines bearing HBV surface antigens: S-, M- and L-HBsAg. These were multiplied through axillary buds to avoid the risk of somaclonal variation. Micropropagation effectiveness reached 3.5-5.7 per passage, which implies potential production of up to 6600 plant clones within a maximum 5 months. Multiplication and rooting rates were statistically homogenous for most transgenic and control plants. For most lines, more than 90 % of clones obtained via in vitro micropropagation had HBsAg content as high as reference plants directly developed from seeds. Clones were also several times more uniform in HBsAg expression. Variation coefficients of HBsAg content did not exceed 10 % for approximately 40-85 % of clones, or reached a maximum 20 % for 90 % of all clones. Tissue culture did not affect total and leaf biomass yields. Seed production for clones was decreased insignificantly and did not impact progeny condition. Micropropagation facilitates a substantial increase in the production of lettuce plants with high and considerably equalised HBsAg contents. This, together with the previously reported optimisation of plant tissue processing and its long-term stability, constitutes a successive step in manufacturing of a standardised anti-HBV oral vaccine of reliable efficacy.

Recurrent variational approach to the two-leg Hubbard ladder

International Nuclear Information System (INIS)

Kim, E.H.; Sierra, G.; Duffy, D.

1999-01-01

We applied the recurrent variational approach to the two-leg Hubbard ladder. At half filling, our variational ansatz was a generalization of the resonating valence-bond state. At finite doping, hole pairs were allowed to move in the resonating valence-bond background. The results obtained by the recurrent variational approach were compared with results from density matrix renormalization group. copyright 1999 The American Physical Society

On the correspondence between quantum and classical variational principles

International Nuclear Information System (INIS)

Ruiz, D.E.; Dodin, I.Y.

2015-01-01

Classical variational principles can be deduced from quantum variational principles via formal reparameterization of the latter. It is shown that such reparameterization is possible without invoking any assumptions other than classicality and without appealing to dynamical equations. As examples, first principle variational formulations of classical point-particle and cold-fluid motion are derived from their quantum counterparts for Schrödinger, Pauli, and Klein–Gordon particles

Variational functionals which admit discontinuous trial functions

International Nuclear Information System (INIS)

Nelson, P. Jr.

1975-01-01

It is argued that variational synthesis with discontinuous trial functions requires variational principles applicable to equations involving operators acting between distinct Hilbert spaces. A description is given of a Roussopoulos-type variational principle generalized to cover this situation. This principle is suggested as the basis for a unified approach to the derivation of variational functionals. In addition to esthetics, this approach has the advantage that the mathematical details increase the understanding of the derived functional, particularly the sense in which a synthesized solution should be regarded as an approximation to the true solution. By way of illustration, the generalized Roussopoulos principle is applied to derive a class of first-order diffusion functionals which admit trial functions containing approximations at an interface. These ''asymptotic'' interface quantities are independent of the limiting approximations from either side and permit use of different trial spectra at and on either side of an interface. The class of functionals derived contains as special cases both the Lagrange multiplier method of Buslik and two functionals of Lambropoulos and Luco. Some numerical results for a simple two-group model confirm that the ''multipliers'' can closely approximate the appropriate quantity in the region near an interface. (U.S.)

In silico detection of sequence variations modifying transcriptional regulation.

Directory of Open Access Journals (Sweden)

Malin C Andersen

2008-01-01

Full Text Available Identification of functional genetic variation associated with increased susceptibility to complex diseases can elucidate genes and underlying biochemical mechanisms linked to disease onset and progression. For genes linked to genetic diseases, most identified causal mutations alter an encoded protein sequence. Technological advances for measuring RNA abundance suggest that a significant number of undiscovered causal mutations may alter the regulation of gene transcription. However, it remains a challenge to separate causal genetic variations from linked neutral variations. Here we present an in silico driven approach to identify possible genetic variation in regulatory sequences. The approach combines phylogenetic footprinting and transcription factor binding site prediction to identify variation in candidate cis-regulatory elements. The bioinformatics approach has been tested on a set of SNPs that are reported to have a regulatory function, as well as background SNPs. In the absence of additional information about an analyzed gene, the poor specificity of binding site prediction is prohibitive to its application. However, when additional data is available that can give guidance on which transcription factor is involved in the regulation of the gene, the in silico binding site prediction improves the selection of candidate regulatory polymorphisms for further analyses. The bioinformatics software generated for the analysis has been implemented as a Web-based application system entitled RAVEN (regulatory analysis of variation in enhancers. The RAVEN system is available at http://www.cisreg.ca for all researchers interested in the detection and characterization of regulatory sequence variation.

In Silico Detection of Sequence Variations Modifying Transcriptional Regulation

Science.gov (United States)

Andersen, Malin C; Engström, Pär G; Lithwick, Stuart; Arenillas, David; Eriksson, Per; Lenhard, Boris; Wasserman, Wyeth W; Odeberg, Jacob

2008-01-01

Identification of functional genetic variation associated with increased susceptibility to complex diseases can elucidate genes and underlying biochemical mechanisms linked to disease onset and progression. For genes linked to genetic diseases, most identified causal mutations alter an encoded protein sequence. Technological advances for measuring RNA abundance suggest that a significant number of undiscovered causal mutations may alter the regulation of gene transcription. However, it remains a challenge to separate causal genetic variations from linked neutral variations. Here we present an in silico driven approach to identify possible genetic variation in regulatory sequences. The approach combines phylogenetic footprinting and transcription factor binding site prediction to identify variation in candidate cis-regulatory elements. The bioinformatics approach has been tested on a set of SNPs that are reported to have a regulatory function, as well as background SNPs. In the absence of additional information about an analyzed gene, the poor specificity of binding site prediction is prohibitive to its application. However, when additional data is available that can give guidance on which transcription factor is involved in the regulation of the gene, the in silico binding site prediction improves the selection of candidate regulatory polymorphisms for further analyses. The bioinformatics software generated for the analysis has been implemented as a Web-based application system entitled RAVEN (regulatory analysis of variation in enhancers). The RAVEN system is available at http://www.cisreg.ca for all researchers interested in the detection and characterization of regulatory sequence variation. PMID:18208319

Simultaneous Structural Variation Discovery in Multiple Paired-End Sequenced Genomes

Science.gov (United States)

Hormozdiari, Fereydoun; Hajirasouliha, Iman; McPherson, Andrew; Eichler, Evan E.; Sahinalp, S. Cenk

Next generation sequencing technologies have been decreasing the costs and increasing the world-wide capacity for sequence production at an unprecedented rate, making the initiation of large scale projects aiming to sequence almost 2000 genomes [1]. Structural variation detection promises to be one of the key diagnostic tools for cancer and other diseases with genomic origin. In this paper, we study the problem of detecting structural variation events in two or more sequenced genomes through high throughput sequencing . We propose to move from the current model of (1) detecting genomic variations in single next generation sequenced (NGS) donor genomes independently, and (2) checking whether two or more donor genomes indeed agree or disagree on the variations (in this paper we name this framework Independent Structural Variation Discovery and Merging - ISV&M), to a new model in which we detect structural variation events among multiple genomes simultaneously.

Seed predators exert selection on the subindividual variation of seed size.

Science.gov (United States)

Sobral, M; Guitián, J; Guitián, P; Larrinaga, A R

2014-07-01

Subindividual variation among repeated organs in plants constitutes an overlooked level of variation in phenotypic selection studies, despite being a major component of phenotypic variation. Animals that interact with plants could be selective agents on subindividual variation. This study examines selective pressures exerted during post-dispersal seed predation and germination on the subindividual variation of seed size in hawthorn (Crataegus monogyna). With a seed offering experiment and a germination test, we estimated phenotypic selection differentials for average and subindividual variation of seed size due to seed predation and germination. Seed size affects germination, growth rate and the probability of an individual seed of escaping predation. Longer seeds showed higher germination rates, but this did not result in significant selection on phenotypes of the maternal trees. On the other hand, seed predators avoided wider seeds, and by doing so exerted phenotypic selection on adult average and subindividual variation of seed size. The detected selection on subindividual variation suggests that the levels of phenotypic variation within individual plants may be, at least partly, the adaptive consequence of animal-mediated selection. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Task demands and individual variation in referring expressions

NARCIS (Netherlands)

Baltaretu, Adriana-Alexandra; Castro Ferreira, Thiago

Aiming to improve the human-likeness of natural language generation systems, this study investigates different sources of variation that might influence the production of referring expressions (REs), namely the effect of task demands and inter- intra- individual variation. We collected REs using a

Natural variations in the geomagnetically trapped electron population

Science.gov (United States)

Vampola, A. L.

1972-01-01

Temporal variations in the trapped natural electron flux intensities and energy spectra are discussed and demonstrated using recent satellite data. These data are intended to acquaint the space systems engineer with the types of natural variations that may be encountered during a mission and to augment the models of the electron environment currently being used in space system design and orbit selection. An understanding of the temporal variations which may be encountered should prove helpful. Some of the variations demonstrated here which are not widely known include: (1) addition of very energetic electrons to the outer zone during moderate magnetic storms: (2) addition of energetic electrons to the inner zone during major magnetic storms; (3) inversions in the outer zone electron energy spectrum during the decay phase of a storm injection event and (4) occasional formation of multiple maxima in the flux vs altitude profile of moderately energetic electrons.

Resolving Rapid Variation in Energy for Particle Transport

Energy Technology Data Exchange (ETDEWEB)

Haut, Terry Scot [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Ahrens, Cory Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Jonko, Alexandra [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Till, Andrew Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division; Lowrie, Robert Byron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Computer, Computational, and Statistical Sciences Division

2016-08-23

Resolving the rapid variation in energy in neutron and thermal radiation transport is needed for the predictive simulation capability in high-energy density physics applications. Energy variation is difficult to resolve due to rapid variations in cross sections and opacities caused by quantized energy levels in the nuclei and electron clouds. In recent work, we have developed a new technique to simultaneously capture slow and rapid variations in the opacities and the solution using homogenization theory, which is similar to multiband (MB) and to the finite-element with discontiguous support (FEDS) method, but does not require closure information. We demonstrated the accuracy and efficiency of the method for a variety of problems. We are researching how to extend the method to problems with multiple materials and the same material but with different temperatures and densities. In this highlight, we briefly describe homogenization theory and some results.

Variational constraints for electrical-impedance tomography

International Nuclear Information System (INIS)

Berryman, J.G.; Kohn, R.V.

1990-01-01

The task of electrical-impedance tomography is to invert boundary measurements for the conductivity distribution of a body. This inverse problem can be formulated so the primary data are the measured powers dissipated across injection electrodes. Then, since these powers are minima of the pertinent (dual) variational principles, feasibility constraints can be found for the nonlinear inversion problem. When power may be measured accurately, the existence of these dual variational principles implies that any exact solution must lie at a point of intersection of the two feasibility boundaries

Genetic variations in multiple myeloma I

DEFF Research Database (Denmark)

Vangsted, A.; Klausen, T.W.; Vogel, Ulla Birgitte

2012-01-01

Few risk factors have been established for the plasma cell disorder multiple myeloma, but some of these like African American ethnicity and a family history of B-cell lymphoproliferative diseases suggest a genetic component for the disease. Genetic variation represents the genetic basis of variab......Few risk factors have been established for the plasma cell disorder multiple myeloma, but some of these like African American ethnicity and a family history of B-cell lymphoproliferative diseases suggest a genetic component for the disease. Genetic variation represents the genetic basis...

A probabilistic Hu-Washizu variational principle

Science.gov (United States)

Liu, W. K.; Belytschko, T.; Besterfield, G. H.

1987-01-01

A Probabilistic Hu-Washizu Variational Principle (PHWVP) for the Probabilistic Finite Element Method (PFEM) is presented. This formulation is developed for both linear and nonlinear elasticity. The PHWVP allows incorporation of the probabilistic distributions for the constitutive law, compatibility condition, equilibrium, domain and boundary conditions into the PFEM. Thus, a complete probabilistic analysis can be performed where all aspects of the problem are treated as random variables and/or fields. The Hu-Washizu variational formulation is available in many conventional finite element codes thereby enabling the straightforward inclusion of the probabilistic features into present codes.

Geometric Total Variation for Texture Deformation

DEFF Research Database (Denmark)

Bespalov, Dmitriy; Dahl, Anders Lindbjerg; Shokoufandeh, Ali

2010-01-01

In this work we propose a novel variational method that we intend to use for estimating non-rigid texture deformation. The method is able to capture variation in grayscale images with respect to the geometry of its features. Our experimental evaluations demonstrate that accounting for geometry...... of features in texture images leads to significant improvements in localization of these features, when textures undergo geometrical transformations. Accurate localization of features in the presense of unkown deformations is a crucial property for texture characterization methods, and we intend to expoit...

Overlapping constraint for variational surface reconstruction

DEFF Research Database (Denmark)

Aanæs, Henrik; Solem, J.E.

2005-01-01

In this paper a counter example, illustrating a shortcoming in most variational formulations for 3D surface estimation, is presented. The nature of this shortcoming is a lack of an overlapping constraint. A remedy for this shortcoming is presented in the form of a penalty function with an analysi...... of the effects of this function on surface motion. For practical purposes, this will only have minor influence on current methods. However, the insight provided in the analysis is likely to influence future developments in the field of variational surface reconstruction....

DNA methylation-based variation between human populations.

Science.gov (United States)

Kader, Farzeen; Ghai, Meenu

2017-02-01

Several studies have proved that DNA methylation affects regulation of gene expression and development. Epigenome-wide studies have reported variation in methylation patterns between populations, including Caucasians, non-Caucasians (Blacks), Hispanics, Arabs, and numerous populations of the African continent. Not only has DNA methylation differences shown to impact externally visible characteristics, but is also a potential biomarker for underlying racial health disparities between human populations. Ethnicity-related methylation differences set their mark during early embryonic development. Genetic variations, such as single-nucleotide polymorphisms and environmental factors, such as age, dietary folate, socioeconomic status, and smoking, impacts DNA methylation levels, which reciprocally impacts expression of phenotypes. Studies show that it is necessary to address these external influences when attempting to differentiate between populations since the relative impacts of these factors on the human methylome remain uncertain. The present review summarises several reported attempts to establish the contribution of differential DNA methylation to natural human variation, and shows that DNA methylation could represent new opportunities for risk stratification and prevention of several diseases amongst populations world-wide. Variation of methylation patterns between human populations is an exciting prospect which inspires further valuable research to apply the concept in routine medical and forensic casework. However, trans-generational inheritance needs to be quantified to decipher the proportion of variation contributed by DNA methylation. The future holds thorough evaluation of the epigenome to understand quantification, heritability, and the effect of DNA methylation on phenotypes. In addition, methylation profiling of the same ethnic groups across geographical locations will shed light on conserved methylation differences in populations.

Solar cycle variations in mesospheric carbon monoxide

Science.gov (United States)

Lee, Jae N.; Wu, Dong L.; Ruzmaikin, Alexander; Fontenla, Juan

2018-05-01

As an extension of Lee et al. (2013), solar cycle variation of carbon monoxide (CO) is analyzed with MLS observation, which covers more than thirteen years (2004-2017) including maximum of solar cycle 24. Being produced primarily by the carbon dioxide (CO2) photolysis in the lower thermosphere, the variations of the mesospheric CO concentration are largely driven by the solar cycle modulated ultraviolet (UV) variation. This solar signal extends down to the lower altitudes by the dynamical descent in the winter polar vortex, showing a time lag that is consistent with the average descent velocity. To characterize a global distribution of the solar impact, MLS CO is correlated with the SORCE measured total solar irradiance (TSI) and UV. As high as 0.8 in most of the polar mesosphere, the linear correlation coefficients between CO and UV/TSI are more robust than those found in the previous work. The photochemical contribution explains most (68%) of the total variance of CO while the dynamical contribution accounts for 21% of the total variance at upper mesosphere. The photochemistry driven CO anomaly signal is extended in the tropics by vertical mixing. The solar cycle signal in CO is further examined with the Whole Atmosphere Community Climate Model (WACCM) 3.5 simulation by implementing two different modeled Spectral Solar Irradiances (SSIs): SRPM 2012 and NRLSSI. The model simulations underestimate the mean CO amount and solar cycle variations of CO, by a factor of 3, compared to those obtained from MLS observation. Different inputs of the solar spectrum have small impacts on CO variation.

SYSTEMATIC AND STOCHASTIC VARIATIONS IN PULSAR DISPERSION MEASURES

International Nuclear Information System (INIS)

Lam, M. T.; Cordes, J. M.; Chatterjee, S.; Jones, M. L.; McLaughlin, M. A.; Armstrong, J. W.

2016-01-01

We analyze deterministic and random temporal variations in the dispersion measure (DM) from the full three-dimensional velocities of pulsars with respect to the solar system, combined with electron-density variations over a wide range of length scales. Previous treatments have largely ignored pulsars’ changing distances while favoring interpretations involving changes in sky position from transverse motion. Linear trends in pulsar DMs observed over 5–10 year timescales may signify sizable DM gradients in the interstellar medium (ISM) sampled by the changing direction of the line of sight to the pulsar. We show that motions parallel to the line of sight can also account for linear trends, for the apparent excess of DM variance over that extrapolated from scintillation measurements, and for the apparent non-Kolmogorov scalings of DM structure functions inferred in some cases. Pulsar motions through atomic gas may produce bow-shock ionized gas that also contributes to DM variations. We discuss the possible causes of periodic or quasi-periodic changes in DM, including seasonal changes in the ionosphere, annual variations of the solar elongation angle, structure in the heliosphere and ISM boundary, and substructure in the ISM. We assess the solar cycle’s role on the amplitude of ionospheric and solar wind variations. Interstellar refraction can produce cyclic timing variations from the error in transforming arrival times to the solar system barycenter. We apply our methods to DM time series and DM gradient measurements in the literature and assess their consistency with a Kolmogorov medium. Finally, we discuss the implications of DM modeling in precision pulsar timing experiments

Dopamine transporters govern diurnal variation in extracellular dopamine tone

OpenAIRE

Ferris, Mark J.; España, Rodrigo A.; Locke, Jason L.; Konstantopoulos, Joanne K.; Rose, Jamie H.; Chen, Rong; Jones, Sara R.

2014-01-01

The mechanism for diurnal (i.e., light/dark) oscillations in extracellular dopamine tone in mesolimbic and nigrostriatal systems is unknown. This is because, unlike other neurotransmitter systems, variation in dopamine tone does not correlate with variation in dopamine cell firing. The current research pinpoints the dopamine transporter as a critical governor of diurnal variation in both extracellular dopamine tone and the intracellular availability of releasable dopamine. These data describe...

Solar UV Variations During the Decline of Cycle 23

Science.gov (United States)

DeLand, Matthew, T.; Cebula, Richard P.

2011-01-01

Characterization of temporal and spectral variations in solar ultraviolet irradiance over a solar cycle is essential for understanding the forcing of Earth's atmosphere and climate. Satellite measurements of solar UV variability for solar cycles 21, 22, and 23 show consistent solar cycle irradiance changes at key wavelengths (e.g. 205 nm, 250 nm) within instrumental uncertainties. All historical data sets also show the same relative spectral dependence for both short-term (rotational) and long-term (solar cycle) variations. Empirical solar irradiance models also produce long-term solar UV variations that agree well with observational data. Recent UV irradiance data from the Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instruments covering the declining phase of Cycle 23 present a different picture oflong-term solar variations from previous results. Time series of SIM and SOLSTICE spectral irradiance data between 2003 and 2007 show solar variations that greatly exceed both previous measurements and predicted irradiance changes over this period, and the spectral dependence of the SIM and SOLSTICE variations during these years do not show features expected from solar physics theory. The use of SORCE irradiance variations in atmospheric models yields substantially different middle atmosphere ozone responses in both magnitude and vertical structure. However, short-term solar variability derived from SIM and SOLSTICE UV irradiance data is consistent with concurrent solar UV measurements from other instruments, as well as previous results, suggesting no change in solar physics. Our analysis of short-term solar variability is much less sensitive to residual instrument response changes than the observations of long-term variations. The SORCE long-term UV results can be explained by under-correction of instrument response changes during the first few years of measurements

Allozyme variation in spineless Pejibaye (Bactris gasipaes Kunth)

Science.gov (United States)

Isozyme variation was studied in 161 accessions of pineapple including four species of Ananas and one of Pseudananas. Six enzyme systems (ADH, GPI, PGM, SKDH, TPI, UGPP) involving seven putative loci revealed 35 electromorphs . Considerable variation exists within and between species of Ananas. Sixt...

Comparison of predicted and measured variations of indoor radon concentration

International Nuclear Information System (INIS)

Arvela, H.; Voutilainen, A.; Maekelaeinen, I.; Castren, O.; Winqvist, K.

1988-01-01

Prediction of the variations of indoor radon concentration were calculated using a model relating indoor radon concentration to radon entry rate, air infiltration and meteorological factors. These calculated variations have been compared with seasonal variations of 33 houses during 1-4 years, with winter-summer concentration ratios of 300 houses and the measured diurnal variation. In houses with a slab in ground contact the measured seasonal variations are quite often in agreement with variations predicted for nearly pure pressure difference driven flow. The contribution of a diffusion source is significant in houses with large porous concrete walls against the ground. Air flow due to seasonally variable thermal convection within eskers strongly affects the seasonal variations within houses located thereon. Measured and predicted winter-summer concentration ratios demonstrate that, on average, the ratio is a function of radon concentration. The ratio increases with increasing winter concentration. According to the model the diurnal maximum caused by a pressure difference driven flow occurs in the morning, a finding which is in agreement with the measurements. The model presented can be used for differentiating between factors affecting radon entry into houses. (author)

Small-scale density variations in the lunar crust revealed by GRAIL

Science.gov (United States)

Jansen, J. C.; Andrews-Hanna, J. C.; Li, Y.; Lucey, P. G.; Taylor, G. J.; Goossens, S.; Lemoine, F. G.; Mazarico, E.; Head, J. W.; Milbury, C.; Kiefer, W. S.; Soderblom, J. M.; Zuber, M. T.

2017-07-01

Data from the Gravity Recovery and Interior Laboratory (GRAIL) mission have revealed that ∼98% of the power of the gravity signal of the Moon at high spherical harmonic degrees correlates with the topography. The remaining 2% of the signal, which cannot be explained by topography, contains information about density variations within the crust. These high-degree Bouguer gravity anomalies are likely caused by small-scale (10‧s of km) shallow density variations. Here we use gravity inversions to model the small-scale three-dimensional variations in the density of the lunar crust. Inversion results from three non-descript areas yield shallow density variations in the range of 100-200 kg/m3. Three end-member scenarios of variations in porosity, intrusions into the crust, and variations in bulk crustal composition were tested as possible sources of the density variations. We find that the density anomalies can be caused entirely by changes in porosity. Characteristics of density anomalies in the South Pole-Aitken basin also support porosity as a primary source of these variations. Mafic intrusions into the crust could explain many, but not all of the anomalies. Additionally, variations in crustal composition revealed by spectral data could only explain a small fraction of the density anomalies. Nevertheless, all three sources of density variations likely contribute. Collectively, results from this study of GRAIL gravity data, combined with other studies of remote sensing data and lunar samples, show that the lunar crust exhibits variations in density by ± 10% over scales ranging from centimeters to 100‧s of kilometers.

Variation and Linguistic Theory.

Science.gov (United States)

Bailey, Charles-James N.

This volume presents principles and models for describing language variation, and introduces a time-based, dynamic framework for linguistic description. The book first summarizes some of the problems of grammatical description encountered from Saussure through the present and then outlines possibilities for new descriptions of language which take…

Variational principles for dissipative waves

Science.gov (United States)

Dodin, I. Y.; Ruiz, D. E.

2016-10-01

Variational methods are a powerful tool in plasma theory. However, their applications are typically restricted to conservative systems or require doubling of variables, which often contradicts the purpose of the variational approach altogether. We show that these restrictions can be relaxed for some classes of dynamical systems that are of practical interest in plasma physics, particularly including dissipative plasma waves. Applications will be discussed to calculating dispersion relations and modulational dynamics of individual plasma waves and wave ensembles. The work was supported by the NNSA SSAA Program through DOE Research Grant No. DE-NA0002948, by the U.S. DOE through Contract No. DE-AC02-09CH11466, and by the U.S. DOD NDSEG Fellowship through Contract No. 32-CFR-168a.

Tidal variations of earth rotation

Science.gov (United States)

Yoder, C. F.; Williams, J. G.; Parke, M. E.

1981-01-01

The periodic variations of the earths' rotation resulting from the tidal deformation of the earth by the sun and moon were rederived including terms with amplitudes of 0.002 millisec and greater. The series applies to the mantle, crust, and oceans which rotate together for characteristic tidal periods; the scaling parameter is the ratio of the fraction of the Love number producing tidal variations in the moment of inertia of the coupled mantle and oceans (k) to the dimensionless polar moment of inertia of the coupled moments (C). The lunar laser ranging data shows that k/C at monthly and fortnightly frequencies equals 0.99 + or - 0.15 and 0.99 + or - 0.20 as compared to the theoretical value of 0.94 + or - 0.04.

Does geography or ecology best explain 'cultural' variation among chimpanzee communities?

Science.gov (United States)

Kamilar, Jason M; Marshack, Joshua L

2012-02-01

Much attention has been paid to geographic variation in chimpanzee behavior, but few studies have applied quantitative techniques to explain this variation. Here, we apply methods typically utilized in macroecology to explain variation in the putative cultural traits of chimpanzees. We analyzed published data containing 39 behavioral traits from nine chimpanzee communities. We used a canonical correspondence analysis to examine the relative importance of environmental characteristics and geography, which may be a proxy for inter-community gene flow and/or social transmission, for explaining geographic variation in chimpanzee behavior. We found that geography, and longitude in particular, was the best predictor of behavioral variation. Chimpanzee communities in close longitudinal proximity to each other exhibit similar behavioral repertoires, independent of local ecological factors. No ecological variables were significantly related to behavioral variation. These results support the idea that inter-community dispersal patterns have played a major role in structuring behavioral variation. We cannot be certain whether behavioral variation has a genetic basis, is the result of innovation and diffusion, or a combination of the two. Copyright © 2011 Elsevier Ltd. All rights reserved.

Variation of clinical expression in patients with Stargardt dystrophy and sequence variations in the ABCR gene.

Science.gov (United States)

Fishman, G A; Stone, E M; Grover, S; Derlacki, D J; Haines, H L; Hockey, R R

1999-04-01

To report the spectrum of ophthalmic findings in patients with Stargardt dystrophy or fundus flavimaculatus who have a specific sequence variation in the ABCR gene. Twenty-nine patients with Stargardt dystrophy or fundus flavimaculatus from different pedigrees were identified with possible disease-causing sequence variations in the ABCR gene from a group of 66 patients who were screened for sequence variations in this gene. Patients underwent a routine ocular examination, including slitlamp biomicroscopy and a dilated fundus examination. Fluorescein angiography was performed on 22 patients, and electroretinographic measurements were obtained on 24 of 29 patients. Kinetic visual fields were measured with a Goldmann perimeter in 26 patients. Single-strand conformation polymorphism analysis and DNA sequencing were used to identify variations in coding sequences of the ABCR gene. Three clinical phenotypes were observed among these 29 patients. In phenotype I, 9 of 12 patients had a sequence change in exon 42 of the ABCR gene in which the amino acid glutamic acid was substituted for glycine (Gly1961Glu). In only 4 of these 9 patients was a second possible disease-causing mutation found on the other ABCR allele. In addition to an atrophic-appearing macular lesion, phenotype I was characterized by localized perifoveal yellowish white flecks, the absence of a dark choroid, and normal electroretinographic amplitudes. Phenotype II consisted of 10 patients who showed a dark choroid and more diffuse yellowish white flecks in the fundus. None exhibited the Gly1961Glu change. Phenotype III consisted of 7 patients who showed extensive atrophic-appearing changes of the retinal pigment epithelium. Electroretinographic cone and rod amplitudes were reduced. One patient showed the Gly1961Glu change. A wide variation in clinical phenotype can occur in patients with sequence changes in the ABCR gene. In individual patients, a certain phenotype seems to be associated with the presence of

Structural genomic variations and Parkinson's disease.

Science.gov (United States)

Bandrés-Ciga, Sara; Ruz, Clara; Barrero, Francisco J; Escamilla-Sevilla, Francisco; Pelegrina, Javier; Vives, Francisco; Duran, Raquel

2017-10-01

Parkinson's disease (PD) is the second most common neurodegenerative disease, whose prevalence is projected to be between 8.7 and 9.3 million by 2030. Until about 20 years ago, PD was considered to be the textbook example of a "non-genetic" disorder. Nowadays, PD is generally considered a multifactorial disorder that arises from the combination and complex interaction of genes and environmental factors. To date, a total of 7 genes including SNCA, LRRK2, PARK2, DJ-1, PINK 1, VPS35 and ATP13A2 have been seen to cause unequivocally Mendelian PD. Also, variants with incomplete penetrance in the genes LRRK2 and GBA are considered to be strong risk factors for PD worldwide. Although genetic studies have provided valuable insights into the pathogenic mechanisms underlying PD, the role of structural variation in PD has been understudied in comparison with other genomic variations. Structural genomic variations might substantially account for such genetic substrates yet to be discovered. The present review aims to provide an overview of the structural genomic variants implicated in the pathogenesis of PD.

Light Curve Variations of AR Lacertae

Directory of Open Access Journals (Sweden)

Il-Seong Nha

1991-12-01

Full Text Available Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1 The light variations outside eclipse follow none of the wave migration patterns reported by previous investigators. (2 Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests that, in the future, AR Lac has a chance to attain a normal state with mo complicated interactions. (3 The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4 The K0 star, the larger component, has brightened by 0.m14 V, while the G2 star has shown a fluctuation of about 0.m05 in V. (5 The B-V values at primary mid-eclipse have no correlation with the depth variations. (6 Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

Geometrical treatment of non-potential interactions: the exterior variational calculus, dynamical systems, physical 1-forms and variational selfadjointness

International Nuclear Information System (INIS)

Trostel, R.

1982-01-01

A mathematical objective of this paper is to provide geometrical formulation of the integrability conditions for the existence of an action functional, that is, to provide a geometrical counterpart (similar to that by Abraham, Marsden, and Hughes) of the variational and functional approach to self-adjointness. This objective is achieved via the exterior variational calculus, an exterior differential calculus on the vector space of functions depending on time or space time, using from the outset extensively the concept of functional differentiation as its foundation. Variational self-adjointness equals the variational closure of the physical 1-form, the vanishing of a generalized curl-operation applied to the equations of motion. The convenience of this more formal approach is demonstrated, not only when deriving the conditions of variational self-adjointness for materials of differential type of arbitrary order (particles or fields), using roughly no more than Dirac's delta-distributions, but also when treating materials of a broader class (including causal and acausal constitutive functionals, materials of rate type, integral type, etc.). A physical objective of this paper is achieved by pointing out that, as physics is primarily concerned with the solutions of the evolution equations, i.e., with the set of the zero points of the physical 1-form, an equivalence relation among the physical 1-forms on the infinite dimensional vector space of functions is constructed by leaving the set of their zero points unchanged. Using this result, a direct Lagrangian universality is indicated and an almost one presented. Moreover, all physical 1-forms connected by invertible supermatrices (thus mixing the evolution law of different times or space-time) are equivalent. Choosing these supermatrices to be diagonal in time or space-time yields the indirect analytical representation factors

Holocene hydrologic variation at Lake Titicaca, Bolivia/Peru, and its relationship to North Atlantic climate variation

Science.gov (United States)

Baker, P. A.; Fritz, S. C.; Garland, J.; Ekdahl, E.

2005-10-01

A growing number of sites in the Northern Hemisphere show centennial- to millennial-scale climate variation that has been correlated with change in solar variability or with change in North Atlantic circulation. However, it is unclear how (or whether) these oscillations in the climate system are manifest in the Southern Hemisphere because of a lack of sites with suitably high sampling resolution. In this paper, we reconstruct the lake-level history of Lake Titicaca, using the carbon isotopic content of sedimentary organic matter, to evaluate centennial- to millennial-scale precipitation variation and its phasing relative to sites in the Northern Hemisphere. The pattern and timing of lake-level change in Lake Titicaca is similar to the ice-rafted debris record of Holocene Bond events, demonstrating a possible coupling between precipitation variation on the Altiplano and North Atlantic sea-surface temperatures (SSTs). The cold periods of the Holocene Bond events correspond with periods of increased precipitation on the Altiplano. Holocene precipitation variability on the Altiplano is anti-phased with respect to precipitation in the Northern Hemisphere monsoon region. More generally, the tropical Andes underwent large changes in precipitation on centennial-to-millennial timescales during the Holocene.

Seasonal variation of dystocia in a large Danish cohort.

Science.gov (United States)

Rohr Thomsen, Christine; Uldbjerg, Niels; Hvidman, Lone; Atladóttir, Hjördís Ósk; Henriksen, Tine Brink; Milidou, Ioanna

2014-01-01

Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population. We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time. No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91). No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.

Seasonal variation in admission for heart failure, hypertension and ...

African Journals Online (AJOL)

Seasonal variation in admission for heart failure, hypertension and stroke. ... Background: Seasonal variation in hospitalization for cardiovascular disease has been ... hypertension and hypertension – related stroke (Cerebrovascular accident) ...

Assessment of somaclonal variation in somatic embryo-derived plants of yacon [Smallanthus sonchifolius (Poepp. and Endl.) H. Robinson] using inter simple sequence repeat analysis and flow cytometry

Czech Academy of Sciences Publication Activity Database

Viehmannová, I.; Bortlová, Z.; Vítámvás, J.; Čepková, P.; Eliášová, Kateřina; Svobodová, E.; Trávníčková, M.

2014-01-01

Roč. 17, č. 2 (2014) ISSN 0717-3458 Institutional support: RVO:61389030 Keywords : DNA polymorphism * Molecular markers * Ploidy level Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.681, year: 2014

The variational spiked oscillator

International Nuclear Information System (INIS)

Aguilera-Navarro, V.C.; Ullah, N.

1992-08-01

A variational analysis of the spiked harmonic oscillator Hamiltonian -d 2 / d x 2 + x 2 + δ/ x 5/2 , δ > 0, is reported in this work. A trial function satisfying Dirichlet boundary conditions is suggested. The results are excellent for a large range of values of the coupling parameter. (author)

Small-Scale Density Variations in the Lunar Crust Revealed by GRAIL

Science.gov (United States)

Jansen, J. C.; Andrews-Hanna, J. C.; Li, Y.; Lucey, P. G.; Taylor, G. J.; Goossens, S.; Lemoine, F. G.; Mazarico, E.; Head, J. W., III; Milbury, C.;

Construction of A Trial Function In The Variational Procedure of ...

African Journals Online (AJOL)

A form of variational method for calculating the ground state energy of a quantum mechanical system is considered. The method is based on a systematic construction of a trial variational function at each step of the calculation of the ground state energy. The construction involves introducing more variational parameters to ...

Using the Screened Coulomb Potential to Illustrate the Variational Method

Science.gov (United States)

Zuniga, Jose; Bastida, Adolfo; Requena, Alberto

2012-01-01

The screened Coulomb potential, or Yukawa potential, is used to illustrate the application of the single and linear variational methods. The trial variational functions are expressed in terms of Slater-type functions, for which the integrals needed to carry out the variational calculations are easily evaluated in closed form. The variational…

On the formalism of local variational differential operators

NARCIS (Netherlands)

Igonin, S.; Verbovetsky, A.V.; Vitolo, R.

2002-01-01

The calculus of local variational differential operators introduced by B. L. Voronov, I. V. Tyutin, and Sh. S. Shakhverdiev is studied in the context of jet super space geometry. In a coordinate-free way, we relate these operators to variational multivectors, for which we introduce and compute the

Reducing Variation in the Assessment of Student Writing

Science.gov (United States)

Hunter, Kerry; Docherty, Peter

2011-01-01

This paper extends the literature on grader variation and the role of moderation and socialisation processes in reducing this variation. It offers a fresh categorisation of academics' assessment beliefs and expectations, and uses this categorisation to analyse the interaction between implicit and explicit expectations in relation to grader…

Short Communication: Prevalence of hypertension and variation of ...

African Journals Online (AJOL)

Short Communication: Prevalence of hypertension and variation of blood pressure with age among adolescents in Chetla, India. I Saha, B Paul, A Dasgupta. Abstract. This community-based cross-sectional study was carried out to determine the prevalence of hypertension and variation of blood pressure with age among ...

Semi-annual Sq-variation in solar activity cycle

Science.gov (United States)

Pogrebnoy, V.; Malosiev, T.

The peculiarities of semi-annual variation in solar activity cycle have been studied. The data from observatories having long observational series and located in different latitude zones were used. The following observatories were selected: Huancayo (magnetic equator), from 1922 to 1959; Apia (low latitudes), from 1912 to 1961; Moscow (middle latitudes), from 1947 to 1965. Based on the hourly values of H-components, the average monthly diurnal amplitudes (a difference between midday and midnight values), according to five international quiet days, were computed. Obtained results were compared with R (relative sunspot numbers) in the ranges of 0-30R, 40-100R, and 140-190R. It was shown, that the amplitude of semi-annual variation increases with R, from minimum to maximum values, on average by 45%. At equatorial Huancayo observatory, the semi-annual Sq(H)-variation appears especially clearly: its maximums take place at periods of equinoxes (March-April, September-October), and minimums -- at periods of solstices (June-July, December-January). At low (Apia observatory) and middle (Moscow observatory) latitudes, the character of semi-annual variation is somewhat different: it appears during the periods of equinoxes, but considerably less than at equator. Besides, with the growth of R, semi-annual variation appears against a background of annual variation, in the form of second peaks (maximum in June). At observatories located in low and middle latitudes, second peaks become more appreciable with an increase of R (March-April and September-October). During the periods of low solar activity, they are insignificant. This work has been carried out with the support from International Scientific and Technology Center (Project #KR-214).

Geographic variation in expenditures for workers' compensation physician claims.

Science.gov (United States)

Miller, T R; Levy, D T

1997-07-01

We examine interstate variations in the cost of claims for physician care using injury claims from Worker's Compensation, and consider some of the factors that may explain cost differences. Multivariate regression analysis is used to isolate state variations, while controlling for personal and injury characteristics, and state characteristics. Statistical analyses reveal considerable variation in expenditures for physician care of injuries across states, even after controlling for case mix and state characteristics. We also find that the presence of HMOs and of general practitioners as a percent of physicians are associated with lower claims, and that the percent of the state that is urban is associated with higher claims. The large variation in costs suggests a potential to affect the costs of physician care for work-related injuries.

Variational principles for Ginzburg-Landau equation by He's semi-inverse method

International Nuclear Information System (INIS)

Liu, W.Y.; Yu, Y.J.; Chen, L.D.

2007-01-01

Via the semi-inverse method of establishing variational principles proposed by He, a generalized variational principle is established for Ginzburg-Landau equation. The present theory provides a quite straightforward tool to the search for various variational principles for physical problems. This paper aims at providing a more complete theoretical basis for applications using finite element and other direct variational methods

State Variation in Medical Imaging: Despite Great Variation, the Medicare Spending Decline Continues.

Science.gov (United States)

Rosenkrantz, Andrew B; Hughes, Danny R; Duszak, Richard

2015-10-01

The purpose of this study was to assess state-level trends in per beneficiary Medicare spending on medical imaging. Medicare part B 5% research identifiable files from 2004 through 2012 were used to compute national and state-by-state annual average per beneficiary spending on imaging. State-to-state geographic variation and temporal trends were analyzed. National average per beneficiary Medicare part B spending on imaging increased 7.8% annually between 2004 ($350.54) and its peak in 2006 ($405.41) then decreased 4.4% annually between 2006 and 2012 ($298.63). In 2012, annual per beneficiary spending was highest in Florida ($367.25) and New York ($355.67) and lowest in Ohio ($67.08) and Vermont ($72.78). Maximum state-to-state geographic variation increased over time, with the ratio of highest-spending state to lowest-spending state increasing from 4.0 in 2004 to 5.5 in 2012. Spending in nearly all states decreased since peaks in 2005 (six states) or 2006 (43 states). The average annual decrease among states was 5.1% ± 1.8% (range, 1.2-12.2%) The largest decrease was in Ohio. In only two states did per beneficiary spending increase (Maryland, 12.5% average annual increase since 2005; Oregon, 4.8% average annual increase since 2008). Medicare part B average per beneficiary spending on medical imaging declined in nearly every state since 2005 and 2006 peaks, abruptly reversing previously reported trends. Spending continued to increase, however, in Maryland and Oregon. Identification of state-level variation may facilitate future investigation of the potential effect of specific and regional changes in spending on patient access and outcomes.

Climate variations and the enhanced greenhouse effect

Energy Technology Data Exchange (ETDEWEB)

Karlen, W. [Stockholm Univ. (Sweden). Dept. of Physical Geography

1998-06-01

Changes in the size of glaciers, in the altitude of the alpine tree-limit, and variation in the width of tree-rings during the Holocene clearly indicate that the average Scandinavian summer temperature has fluctuated. During warm periods it has been about 2 deg C warmer than at present; during cold periods it has been almost as cold as it was during the coldest decades of the previous centuries. Superimposed on these long-term variations, which have lasted from 100 to 200 years, are short fluctuations in temperature. The Scandinavian chronology, which is based on glacier and alpine tree-limit fluctuations as well as on dendrochronology, is well correlated with the changes in climate, which studies of ice cores from central Greenland have revealed. It is therefore believed that the Scandinavian climate chronology depicts conditions typical of a large area. The Scandinavian record is compared with data concerning solar irradiation variations estimated as {sup 14}C anomalies obtained from tree-rings. A correlation between major changes in climate and variations in solar irradiation points to a solar forcing of the climate. This means that there is no evidence of a human influence on climate so far Special issue. Research for mountain area development: Europe. 64 refs, 3 figs

INTERNAL-CYCLE VARIATION OF SOLAR DIFFERENTIAL ROTATION

International Nuclear Information System (INIS)

Li, K. J.; Xie, J. L.; Shi, X. J.

2013-01-01

The latitudinal distributions of the yearly mean rotation rates measured by Suzuki in 1998 and 2012 and Pulkkinen and Tuominen in 1998 are utilized to investigate internal-cycle variation of solar differential rotation. The rotation rate at the solar equator seems to have decreased since cycle 10 onward. The coefficient B of solar differential rotation, which represents the latitudinal gradient of rotation, is found to be smaller in the several years after the minimum of a solar cycle than in the several years after the maximum time of the cycle, and it peaks several years after the maximum time of the solar cycle. The internal-cycle variation of the solar rotation rates looks similar in profile to that of the coefficient B. A new explanation is proposed to address such a solar-cycle-related variation of the solar rotation rates. Weak magnetic fields may more effectively reflect differentiation at low latitudes with high rotation rates than at high latitudes with low rotation rates, and strong magnetic fields may more effectively repress differentiation at relatively low latitudes than at high latitudes. The internal-cycle variation is inferred as the result of both the latitudinal migration of the surface torsional pattern and the repression of strong magnetic activity in differentiation.

Sea-level Variation Along the Suez Canal

Science.gov (United States)

Eid, F. M.; Sharaf El-Din, S. H.; Alam El-Din, K. A.

1997-05-01

The variation of sea level at 11 stations distributed along the Suez Canal was studied during the period from 1980 to 1986. The ranges of variation in daily mean sea level at Port Said and Port Tawfik are about 60 and 120 cm, respectively. The minimum range of daily variation is at Kantara (47 cm). The fluctuations of the monthly mean sea level between the two ends of the Suez Canal vary from one season to another. From July to December, the sea level at Port Said is higher than that at Port Tawfik, with the maximum difference (10·5 cm) in September. During the rest of the year, the mean sea level at Port Tawfik is higher than that at Port Said, with the maximum difference (31·5 cm) in March. The long-term variations of the annual mean sea level at both Port Said and Port Tawfik for the period from 1923 to 1986 showed a positive trend. The sea level at Port Said increased by about 27·8 cm century -1while it increased by only 9·1 cm century -1at Port Tawfik. This indicates that the difference between sea level at Port Said and Port Tawfik has decreased with time.

Variation in Payment Rates under Medicare's Inpatient Prospective Payment System.

Science.gov (United States)

Krinsky, Sam; Ryan, Andrew M; Mijanovich, Tod; Blustein, Jan

2017-04-01

To measure variation in payment rates under Medicare's Inpatient Prospective Payment System (IPPS) and identify the main payment adjustments that drive variation. Medicare cost reports for all Medicare-certified hospitals, 1987-2013, and Dartmouth Atlas geographic files. We measure the Medicare payment rate as a hospital's total acute inpatient Medicare Part A payment, divided by the standard IPPS payment for its geographic area. We assess variation using several measures, both within local markets and nationally. We perform a factor decomposition to identify the share of variation attributable to specific adjustments. We also describe the characteristics of hospitals receiving different payment rates and evaluate changes in the magnitude of the main adjustments over time. Data downloaded from the Centers for Medicare and Medicaid Services, the National Bureau of Economic Research, and the Dartmouth Atlas. In 2013, Medicare paid for acute inpatient discharges at a rate 31 percent above the IPPS base. For the top 10 percent of discharges, the mean rate was double the IPPS base. Variations were driven by adjustments for medical education and care to low-income populations. The magnitude of variation has increased over time. Adjustments are a large and growing share of Medicare hospital payments, and they create significant variation in payment rates. © Health Research and Educational Trust.

Gene transposition causing natural variation for growth in Arabidopsis thaliana.

Science.gov (United States)

Vlad, Daniela; Rappaport, Fabrice; Simon, Matthieu; Loudet, Olivier

2010-05-13

A major challenge in biology is to identify molecular polymorphisms responsible for variation in complex traits of evolutionary and agricultural interest. Using the advantages of Arabidopsis thaliana as a model species, we sought to identify new genes and genetic mechanisms underlying natural variation for shoot growth using quantitative genetic strategies. More quantitative trait loci (QTL) still need be resolved to draw a general picture as to how and where in the pathways adaptation is shaping natural variation and the type of molecular variation involved. Phenotypic variation for shoot growth in the Bur-0 x Col-0 recombinant inbred line set was decomposed into several QTLs. Nearly-isogenic lines generated from the residual heterozygosity segregating among lines revealed an even more complex picture, with major variation controlled by opposite linked loci and masked by the segregation bias due to the defective phenotype of SG3 (Shoot Growth-3), as well as epistasis with SG3i (SG3-interactor). Using principally a fine-mapping strategy, we have identified the underlying gene causing phenotypic variation at SG3: At4g30720 codes for a new chloroplast-located protein essential to ensure a correct electron flow through the photosynthetic chain and, hence, photosynthesis efficiency and normal growth. The SG3/SG3i interaction is the result of a structural polymorphism originating from the duplication of the gene followed by divergent paralogue's loss between parental accessions. Species-wide, our results illustrate the very dynamic rate of duplication/transposition, even over short periods of time, resulting in several divergent--but still functional-combinations of alleles fixed in different backgrounds. In predominantly selfing species like Arabidopsis, this variation remains hidden in wild populations but is potentially revealed when divergent individuals outcross. This work highlights the need for improved tools and algorithms to resolve structural variation

Practice Variation in Public Sector Internal Auditing

DEFF Research Database (Denmark)

Arena, Marika; Jeppesen, Kim Klarskov

2016-01-01

This article aims to analyze the rise of practice variations in public sector internal auditing (IA), giving special attention to the role of agents’ embeddedness in multiple institutional arrangements. IA's trends of development and the characteristics of the public sector context, in fact, make...... types of IA developed in three case settings, shaped by the agents’ embeddedness in different institutional fields. This article provides a more comprehensive approach to the study of IA adoption and development in public sector organizations than previous literature, and it highlights the relevance...... of the interplay between actors’ contemporary embeddedness in professional systems and the focal social system as a relevant source of practice variation. In this respect, the case of IA can contribute to previous studies of practice variation in the field of management accounting, shedding some light on the types...

Variational principles for the projected breakup amplitude

International Nuclear Information System (INIS)

Hahn, Y.

1976-01-01

Two alternate forms of variational principles for the breakup amplitude describing the two- to three-cluster transition are derived such that all the integrals involved in the intermediate stages are well defined. The first form contains a trial Green's function with which both the initial and final state trial wave functions are constructed. The earlier form of the Kohn-type variational principle derived by Lieber, Rosenberg, and Spruch is recovered, however, when this connection between the trial functions is removed. The second form of the variational principle is derived by projecting out from the trial functions all the open channel components which correspond to the two-cluster structures including the rearrangement channels. The remaining part of the wave functions describes the channels with three-cluster structures, and the integrals involving this part are then mathematically well defined

Heterogeneous treatment in the variational nodal method

International Nuclear Information System (INIS)

Fanning, T.H.

1995-01-01

The variational nodal transport method is reduced to its diffusion form and generalized for the treatment of heterogeneous nodes while maintaining nodal balances. Adapting variational methods to heterogeneous nodes requires the ability to integrate over a node with discontinuous cross sections. In this work, integrals are evaluated using composite gaussian quadrature rules, which permit accurate integration while minimizing computing time. Allowing structure within a nodal solution scheme avoids some of the necessity of cross section homogenization, and more accurately defines the intra-nodal flux shape. Ideally, any desired heterogeneity can be constructed within the node; but in reality, the finite set of basis functions limits the practical resolution to which fine detail can be defined within the node. Preliminary comparison tests show that the heterogeneous variational nodal method provides satisfactory results even if some improvements are needed for very difficult, configurations

Phase rainbow refractometry for accurate droplet variation characterization.

Science.gov (United States)

Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

2016-10-15

We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

Capacities for population-genetic variation and ecological adaptations

Directory of Open Access Journals (Sweden)

Marinković Dragoslav

2007-01-01

Full Text Available In contemporary science of population genetics it is equally complex and important to visualize how adaptive limits of individual variation are determined, as well as to describe the amount and sort of this variation. Almost all century the scientists devoted their efforts to explain the principles and structure of biological variation (genetic, developmental, environmental, interactive, etc., basing its maintenance within existing limits mostly on equilibria proclaimed by Hardy-Weinberg rules. Among numerous model-organisms that have been used to prove these rules and demonstrate new variants within mentioned concepts, Drosophila melanogaster is a kind of queen that is used in thousands of experiments for almost exactly 100 years (CARPENTER 1905, with which numerous discoveries and principles were determined that later turned out to be applicable to all other organisms. It is both, in nature and in laboratory, that Drosophilids were used to demonstrate the basic principles of population-genetic variation that was later applied to other species of animals. In ecological-genetic variation their richness in different environments could be used as an exact indicator of the status of a determined habitat, and its population-genetic structure may definitely point out to a possibility that specific resources of the environment start to be in danger to deteriorate, or to disappear in the near future. This paper shows clear-cut differences among environmental habitats, when populations of Drosophilidae are quantitatively observed in different wild, semi-domestic and domestic environments, demonstrating a highly expressed mutual dependence of these two parameters. A crucial approach is how to estimate the causes that determine the limits of biological, i.e. of individual and population-genetic variation. The realized, i.e. adaptive variation, is much lesser than a total possible variation of a polygenic trait, and in this study, using a moderately

Circadian variation in dominant atrial fibrillation frequency in persistent atrial fibrillation

International Nuclear Information System (INIS)

Sandberg, Frida; Stridh, Martin; Sörnmo, Leif; Bollmann, Andreas; Husser, Daniela

2010-01-01

Circadian variation in atrial fibrillation (AF) frequency is explored in this paper by employing recent advances in signal processing. Once the AF frequency has been estimated and tracked by a hidden Markov model approach, the resulting trend is analyzed for the purpose of detecting and characterizing the presence of circadian variation. With cosinor analysis, the results show that the short-term variations in the AF frequency exceed the variation that may be attributed to circadian. Using the autocorrelation method, circadian variation was found in 13 of 18 ambulatory ECG recordings (Holter) acquired from patients with long-standing persistent AF. Using the ensemble correlation method, the highest AF frequency usually occurred during the afternoon, whereas the lowest usually occurred during late night. It is concluded that circadian variation is present in most patients with long-standing persistent AF though the short-term variation in the AF frequency is considerable and should be taken into account

Variational principles for collective motion: Relation between invariance principle of the Schroedinger equation and the trace variational principle

International Nuclear Information System (INIS)

Klein, A.; Tanabe, K.

1984-01-01

The invariance principle of the Schroedinger equation provides a basis for theories of collective motion with the help of the time-dependent variational principle. It is formulated here with maximum generality, requiring only the motion of intrinsic state in the collective space. Special cases arise when the trial vector is a generalized coherent state and when it is a uniform superposition of collective eigenstates. The latter example yields variational principles uncovered previously only within the framework of the equations of motion method. (orig.)

Convergence analysis of variational and non-variational multigrid algorithms for the Laplace-Beltrami operator

KAUST Repository

Bonito, Andrea; Pasciak, Joseph E.

2012-01-01

is captured well enough by the coarsest grid. The main argument hinges on a perturbation analysis from an auxiliary variational algorithm defined directly on the smooth surface. In addition, the vanishing mean value constraint is imposed on each level, thereby

Seasonal Variation in Epidemiology

Science.gov (United States)

Marrero, Osvaldo

2013-01-01

Seasonality analyses are important in medical research. If the incidence of a disease shows a seasonal pattern, then an environmental factor must be considered in its etiology. We discuss a method for the simultaneous analysis of seasonal variation in multiple groups. The nuts and bolts are explained using simple trigonometry, an elementary…

Paleosecular variations from lake sediments

International Nuclear Information System (INIS)

Lund, S.P.; Banerjee, S.K.

1979-01-01

Data are presented on the secular variations of the magnetization of wet and dry lake sediments for 17 North American locations. The usefullness of this data in terms of the geomagnetic field is discussed

Variational method for integrating radial gradient field

Science.gov (United States)

Legarda-Saenz, Ricardo; Brito-Loeza, Carlos; Rivera, Mariano; Espinosa-Romero, Arturo

2014-12-01

We propose a variational method for integrating information obtained from circular fringe pattern. The proposed method is a suitable choice for objects with radial symmetry. First, we analyze the information contained in the fringe pattern captured by the experimental setup and then move to formulate the problem of recovering the wavefront using techniques from calculus of variations. The performance of the method is demonstrated by numerical experiments with both synthetic and real data.

On the analysis of line profile variations: A statistical approach

International Nuclear Information System (INIS)

McCandliss, S.R.

1988-01-01

This study is concerned with the empirical characterization of the line profile variations (LPV), which occur in many of and Wolf-Rayet stars. The goal of the analysis is to gain insight into the physical mechanisms producing the variations. The analytic approach uses a statistical method to quantify the significance of the LPV and to identify those regions in the line profile which are undergoing statistically significant variations. Line positions and flux variations are then measured and subject to temporal and correlative analysis. Previous studies of LPV have for the most part been restricted to observations of a single line. Important information concerning the range and amplitude of the physical mechanisms involved can be obtained by simultaneously observing spectral features formed over a range of depths in the extended mass losing atmospheres of massive, luminous stars. Time series of a Wolf-Rayet and two of stars with nearly complete spectral coverage from 3940 angstrom to 6610 angstrom and with spectral resolution of R = 10,000 are analyzed here. These three stars exhibit a wide range of both spectral and temporal line profile variations. The HeII Pickering lines of HD 191765 show a monotonic increase in the peak rms variation amplitude with lines formed at progressively larger radii in the Wolf-Rayet star wind. Two times scales of variation have been identified in this star: a less than one day variation associated with small scale flickering in the peaks of the line profiles and a greater than one day variation associated with large scale asymmetric changes in the overall line profile shapes. However, no convincing period phenomena are evident at those periods which are well sampled in this time series

Specific Gravity Variation in a Lower Mississippi Valley Cottonwood Population

Science.gov (United States)

R. E. Farmer; J. R. Wilcox

1966-01-01

Specific gravity varied from 0,32 to 0.46, averaging 0.38. Most of the variation was associated with individual trees; samples within locations accounted for a smaller, but statistically significant, portion of the variation. Variation between locatians was not significant. It was concluded that individual high-density trees' should be sought throughout the...

Triple Hierarchical Variational Inequalities with Constraints of Mixed Equilibria, Variational Inequalities, Convex Minimization, and Hierarchical Fixed Point Problems

Directory of Open Access Journals (Sweden)

Lu-Chuan Ceng

2014-01-01

Full Text Available We introduce and analyze a hybrid iterative algorithm by virtue of Korpelevich's extragradient method, viscosity approximation method, hybrid steepest-descent method, and averaged mapping approach to the gradient-projection algorithm. It is proven that under appropriate assumptions, the proposed algorithm converges strongly to a common element of the fixed point set of infinitely many nonexpansive mappings, the solution set of finitely many generalized mixed equilibrium problems (GMEPs, the solution set of finitely many variational inequality problems (VIPs, the solution set of general system of variational inequalities (GSVI, and the set of minimizers of convex minimization problem (CMP, which is just a unique solution of a triple hierarchical variational inequality (THVI in a real Hilbert space. In addition, we also consider the application of the proposed algorithm to solve a hierarchical fixed point problem with constraints of finitely many GMEPs, finitely many VIPs, GSVI, and CMP. The results obtained in this paper improve and extend the corresponding results announced by many others.

Functional characterization of genetic enzyme variations in human lipoxygenases

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Thomas Horn

2013-01-01

Full Text Available Mammalian lipoxygenases play a role in normal cell development and differentiation but they have also been implicated in the pathogenesis of cardiovascular, hyperproliferative and neurodegenerative diseases. As lipid peroxidizing enzymes they are involved in the regulation of cellular redox homeostasis since they produce lipid hydroperoxides, which serve as an efficient source for free radicals. There are various epidemiological correlation studies relating naturally occurring variations in the six human lipoxygenase genes (SNPs or rare mutations to the frequency for various diseases in these individuals, but for most of the described variations no functional data are available. Employing a combined bioinformatical and enzymological strategy, which included structural modeling and experimental site-directed mutagenesis, we systematically explored the structural and functional consequences of non-synonymous genetic variations in four different human lipoxygenase genes (ALOX5, ALOX12, ALOX15, and ALOX15B that have been identified in the human 1000 genome project. Due to a lack of a functional expression system we resigned to analyze the functionality of genetic variations in the hALOX12B and hALOXE3 gene. We found that most of the frequent non-synonymous coding SNPs are located at the enzyme surface and hardly alter the enzyme functionality. In contrast, genetic variations which affect functional important amino acid residues or lead to truncated enzyme variations (nonsense mutations are usually rare with a global allele frequency<0.1%. This data suggest that there appears to be an evolutionary pressure on the coding regions of the lipoxygenase genes preventing the accumulation of loss-of-function variations in the human population.

Consequences for established design practice from geographical variation of historical rainfall data

DEFF Research Database (Denmark)

Mikkelsen, P.S.; Arnbjerg-Nielsen, K.; Harremoës, P.

1997-01-01

variation and variation due to (correlated) sampling errors. Further analyses indicate that the observed variation can be explained only partially by correlation with regional climatological variables and that a significant residual variation remains, especially for large return periods. The new perceptions...

Variational Perturbation Treatment of the Confined Hydrogen Atom

Science.gov (United States)

Montgomery, H. E., Jr.

2011-01-01

The Schrodinger equation for the ground state of a hydrogen atom confined at the centre of an impenetrable cavity is treated using variational perturbation theory. Energies calculated from variational perturbation theory are comparable in accuracy to the results from a direct numerical solution. The goal of this exercise is to introduce the…

Problems of phenomenological simulation of the Dst variation

International Nuclear Information System (INIS)

Gul'el'mi, A.V.

1988-01-01

Stochastic generalization of RBM model, describing the D st -variation is suggested. The corresponding Fokker-Planck equation contains a new phenomenological parameter enabling to obtain the interval estimation of D st forecast. The structure of sources and sinks forming the D st -variation is considered from the viewpoint of critical phenomenon theory

Variations in antibiotic use for respiratory tract infections

Directory of Open Access Journals (Sweden)

Rachel Mckay

2017-04-01

These are preliminary results, with full analytic results available in the coming months. These results will have implications for better understanding the extent of variations in antibiotic prescribing, and some of the drivers of these variations, as well as the potential to inform ongoing efforts to improve the appropriateness of antibiotic use.

Variation of the extinction law in the Trifid nebula

OpenAIRE

Cambrésy, L.; Rho, J.; Marshall, D. J.; Reach, W. T.

2011-01-01

Context. In the past few years, the extinction law has been measured in the infrared wavelengths for various molecular clouds and different laws have been obtained. Aims. In this paper we seek variations of the extinction law within the Trifid nebula region. Such variations would demonstrate local dust evolution linked to variation of the environment parameters such as the density or the interstellar radiation field. Methods. The extinction values, A_λ/A_v, are obtained using the 2MASS, UKIDS...

A formalism for the calculus of variations with spinors

Energy Technology Data Exchange (ETDEWEB)

Bäckdahl, Thomas, E-mail: thobac@chalmers.se [The School of Mathematics, University of Edinburgh, JCMB 6228, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom and Mathematical Sciences - Chalmers University of Technology and University of Gothenburg - SE-412 96 Gothenburg (Sweden); Valiente Kroon, Juan A., E-mail: j.a.valiente-kroon@qmul.ac.uk [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom)

2016-02-15

We develop a frame and dyad gauge-independent formalism for the calculus of variations of functionals involving spinorial objects. As a part of this formalism, we define a modified variation operator which absorbs frame and spin dyad gauge terms. This formalism is applicable to both the standard spacetime (i.e., SL(2, ℂ)) 2-spinors as well as to space (i.e., SU(2, ℂ)) 2-spinors. We compute expressions for the variations of the connection and the curvature spinors.

A formalism for the calculus of variations with spinors

International Nuclear Information System (INIS)

Bäckdahl, Thomas; Valiente Kroon, Juan A.

2016-01-01

We develop a frame and dyad gauge-independent formalism for the calculus of variations of functionals involving spinorial objects. As a part of this formalism, we define a modified variation operator which absorbs frame and spin dyad gauge terms. This formalism is applicable to both the standard spacetime (i.e., SL(2, ℂ)) 2-spinors as well as to space (i.e., SU(2, ℂ)) 2-spinors. We compute expressions for the variations of the connection and the curvature spinors

THEMATIC PROGRESSION VARIATION OF THE GREAT GATSBY ENGLISH-BAHASA INDONESIA TRANSLATIONAL TEXTS

Directory of Open Access Journals (Sweden)

Emi Nursanti

2014-10-01

Full Text Available The data-based research on which this article is based aimed at (1 describing the thematic progression variation of The Great Gatsby texts, (2 describing the contextual factors that motivate the variation in question, and (3 describing the effects of the variation on the texts as translational texts. The study applied a qualitative approach which employed a sematic-translational content analysis of qualitative and quantiative data. The results show that thematic progression variation falls into the low category at average indicated by the mean score of 0.76. The most prominent variation was repre-sented by the low category of variation. The variations were performed by adding or omitting Themes, splitting one units of thematic structure into more than one unit, downranking, not expressing and creating new clauses. The factors that motivate the variation are the different linguistic properties bet-ween English and Bahasa Indonesia and the situational contexts. In terms of effects, the variation caused dangling clauses which cannot be identified from which they are developed. Keywords: thematic progression, thematic structure, Theme, Rheme

Classification of coefficients of variation in experiments with commercial layers

Directory of Open Access Journals (Sweden)

DE Faria Filho

2010-12-01

Full Text Available This study aimed at determining a specific classification of coefficients of variation in experiments with commercial layers. Coefficients of variation were collected from papers published in Brazilian journals between 2000 and 2009 for performance, internal egg quality, and eggshell quality parameters. The coefficients of variation of each parameter were classified as low, intermediate, high, and very high according to the ratio between the median and the pseudo-sigma. It was concluded that the parameters used in experiments with commercial layers have a specific classification of coefficients of variation, and that this must be considered to evaluate experimental accuracy.

Harmonically excited orbital variations

International Nuclear Information System (INIS)

Morgan, T.

1985-01-01

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

Macrophytes shape trophic niche variation among generalist fishes.

Directory of Open Access Journals (Sweden)

Ivana Vejříková

Full Text Available Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N and carbon (δ13C isotopic mixing models, perch (Perca fluviatilis L. and rudd (Scardinius erythrophthalmus (L. showed larger individual variation (i.e., variance in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.. Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence

Macrophytes shape trophic niche variation among generalist fishes

Science.gov (United States)

Vejřík, Lukáš; Šmejkal, Marek; Čech, Martin; Sajdlová, Zuzana; Frouzová, Jaroslava; Kiljunen, Mikko; Peterka, Jiří

2017-01-01

Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall

On a class of general variational inequalities

International Nuclear Information System (INIS)

Siddiqi, A.H.

1990-06-01

The study of variational inequalities was initiated by the Italian Mathematician, Guido Stampacchia in the early 60's. Besides several other important problems of Physics and Engineering this theory has been applied to solve the problem of Elasticity with unilateral constraints. In this paper we introduce a new class of variational inequalities and study the existence and uniqueness of its solution. Error estimates, convergence of approximate solution and the penalty method are also discussed. (author). 25 refs

Vector optimization set-valued and variational analysis

CERN Document Server

Chen, Guang-ya; Yang, Xiaogi

2005-01-01

This book is devoted to vector or multiple criteria approaches in optimization. Topics covered include: vector optimization, vector variational inequalities, vector variational principles, vector minmax inequalities and vector equilibrium problems. In particular, problems with variable ordering relations and set-valued mappings are treated. The nonlinear scalarization method is extensively used throughout the book to deal with various vector-related problems. The results presented are original and should be interesting to researchers and graduates in applied mathematics and operations research

Origins of variation in conducted vasomotor responses

DEFF Research Database (Denmark)

Hald, Bjørn Olav; Welsh, Donald G.; Holstein-Rathlou, Niels-Henrik

2015-01-01

, the efficacy of conducted responses varies significantly between different initiating stimuli within the same vascular bed as well as between different vascular beds following the same stimulus. The differences have stimulated proposals of different mechanisms to account for the experimentally observed...... variation. Using a computational approach that allows for introduction of structural and electrophysiological heterogeneity, we systematically tested variations in both arteriolar electrophysiology and modes of stimuli. Within the same vessel, our simulations show that conduction efficacy is influenced...

Barium variation in Acropora palmata and Montastrea annularis

Science.gov (United States)

Pingitore, Nicholas E.; Rangel, Yolanda; Kwarteng, Andrew

1989-06-01

The barium contents of Acropora palmata and Montastrea annularis are distinct both in their averages (6 and 9 ppm, respectively) and, more impressively, in their variability (5 to 7 ppm and 6 to 15 ppm). A. palmata contained about 50% more Ba2+ than M. annularis and exhibited more than three times as much variation, as measured by their respective coefficients of variation. In contrast, the means and coefficients of variation of Sr2+ in these groups differed by only 6% and 15%. No obvious environmental or post-depositional causes for the inter-and intra-specific variation of Ba2+ could be found. Previous experiments indicate that the partitioning of Ba2+ into aragonite depends directly on the rate of precipitation. This suggests that Ba2+ does not substitute for Ca2+ but instead is incorporated by occlusion. Since growth rates in A. palmata often exceed those of M. annularis, this appears to be the mechanism which generates higher and more variable concentrations of Ba2+ in A. palmata.

Process Variations and Probabilistic Integrated Circuit Design

CERN Document Server

Haase, Joachim

2012-01-01

Uncertainty in key parameters within a chip and between different chips in the deep sub micron era plays a more and more important role. As a result, manufacturing process spreads need to be considered during the design process.  Quantitative methodology is needed to ensure faultless functionality, despite existing process variations within given bounds, during product development.   This book presents the technological, physical, and mathematical fundamentals for a design paradigm shift, from a deterministic process to a probability-orientated design process for microelectronic circuits.  Readers will learn to evaluate the different sources of variations in the design flow in order to establish different design variants, while applying appropriate methods and tools to evaluate and optimize their design.  Trains IC designers to recognize problems caused by parameter variations during manufacturing and to choose the best methods available to mitigate these issues during the design process; Offers both qual...

Smart variations: Functional substructures for part compatibility

KAUST Repository

Zheng, Youyi

2013-05-01

As collections of 3D models continue to grow, reusing model parts allows generation of novel model variations. Naïvely swapping parts across models, however, leads to implausible results, especially when mixing parts across different model families. Hence, the user has to manually ensure that the final model remains functionally valid. We claim that certain symmetric functional arrangements (sFarr-s), which are special arrangements among symmetrically related substructures, bear close relation to object functions. Hence, we propose a purely geometric approach based on such substructures to match, replace, and position triplets of parts to create non-trivial, yet functionally plausible, model variations. We demonstrate that starting even from a small set of models such a simple geometric approach can produce a diverse set of non-trivial and plausible model variations. © 2013 The Author(s) Computer Graphics Forum © 2013 The Eurographics Association and Blackwell Publishing Ltd.

Space Use Variation in Co-Occurring Sister Species: Response to Environmental Variation or Competition?

Science.gov (United States)

Dufour, Claire M. S.; Meynard, Christine; Watson, Johan; Rioux, Camille; Benhamou, Simon; Perez, Julie; du Plessis, Jurie J.; Avenant, Nico; Pillay, Neville; Ganem, Guila

2015-01-01

Coexistence often involves niche differentiation either as the result of environmental divergence, or in response to competition. Disentangling the causes of such divergence requires that environmental variation across space is taken into account, which is rarely done in empirical studies. We address the role of environmental variation versus competition in coexistence between two rodent species: Rhabdomys bechuanae (bechuanae) and Rhabdomys dilectus dilectus (dilectus) comparing their habitat preference and home range (HR) size in areas with similar climates, where their distributions abut (allopatry) or overlap (sympatry). Using Outlying Mean Index analyses, we test whether habitat characteristics of the species deviate significantly from a random sample of available habitats. In allopatry, results suggest habitat selection: dilectus preferring grasslands with little bare soil while bechuanae occurring in open shrublands. In sympatry, shrubland type habitats dominate and differences are less marked, yet dilectus selects habitats with more cover than bechuanae. Interestingly, bechuanae shows larger HRs than dilectus, and both species display larger HRs in sympatry. Further, HR overlaps between species are lower than expected. We discuss our results in light of data on the phylogeography of the genus and propose that evolution in allopatry resulted in adaptation leading to different habitat preferences, even at their distribution margins, a divergence expected to facilitate coexistence. However, since sympatry occurs in sites where environmental characteristics do not allow complete species separation, competition may explain reduced inter-species overlap and character displacement in HR size. This study reveals that both environmental variation and competition may shape species coexistence. PMID:25693176

Partitioning of genetic variation between regulatory and coding gene segments: the predominance of software variation in genes encoding introvert proteins.

Science.gov (United States)

Mitchison, A

1997-01-01

In considering genetic variation in eukaryotes, a fundamental distinction can be made between variation in regulatory (software) and coding (hardware) gene segments. For quantitative traits the bulk of variation, particularly that near the population mean, appears to reside in regulatory segments. The main exceptions to this rule concern proteins which handle extrinsic substances, here termed extrovert proteins. The immune system includes an unusually large proportion of this exceptional category, but even so its chief source of variation may well be polymorphism in regulatory gene segments. The main evidence for this view emerges from genome scanning for quantitative trait loci (QTL), which in the case of the immune system points to a major contribution of pro-inflammatory cytokine genes. Further support comes from sequencing of major histocompatibility complex (Mhc) class II promoters, where a high level of polymorphism has been detected. These Mhc promoters appear to act, in part at least, by gating the back-signal from T cells into antigen-presenting cells. Both these forms of polymorphism are likely to be sustained by the need for flexibility in the immune response. Future work on promoter polymorphism is likely to benefit from the input from genome informatics.

Variation in aerodynamic coefficients with altitude

Science.gov (United States)

Shahid, Faiza; Hussain, Mukkarum; Baig, Mirza Mehmood; Haq, Ihtram ul

Precise aerodynamics performance prediction plays key role for a flying vehicle to get its mission completed within desired accuracy. Aerodynamic coefficients for same Mach number can be different at different altitude due to difference in Reynolds number. Prediction of these aerodynamics coefficients can be made through experiments, analytical solution or Computational Fluid Dynamics (CFD). Advancements in computational power have generated the concept of using CFD as a virtual Wind Tunnel (WT), hence aerodynamic performance prediction in present study is based upon CFD (numerical test rig). Simulations at different altitudes for a range of Mach numbers with zero angle of attack are performed to predict axial force coefficient behavior with altitude (Reynolds number). Similar simulations for a fixed Mach number '3' and a range of angle of attacks are also carried out to envisage the variation in normal force and pitching moment coefficients with altitude (Reynolds number). Results clearly depict that the axial force coefficient is a function of altitude (Reynolds number) and increase as altitude increases, especially for subsonic region. Variation in axial force coefficient with altitude (Reynolds number) slightly increases for larger values of angle of attacks. Normal force and pitching moment coefficients do not depend on altitude (Reynolds number) at smaller values of angle of attacks but show slight decrease as altitude increases. Present study suggests that variation of normal force and pitching moment coefficients with altitude can be neglected but the variation of axial force coefficient with altitude should be considered for vehicle fly in dense atmosphere. It is recommended to continue this study to more complex configurations for various Mach numbers with side slip and real gas effects.

Explaining variation in nascent entrepreneurship

NARCIS (Netherlands)

A.J. van Stel (André); A.R.M. Wennekers (Sander); P. Reynolds (Paul); A.R. Thurik (Roy)

2004-01-01

textabstractThis paper aims at explaining cross-country variation in nascent entrepreneurship. Regression analysis is applied using various explanatory variables derived from three different approaches. We make use of the Global Entrepreneurship Monitor database, including nascent entrepreneurship

Language and Variation: A Study of English and Persian Wh-questions

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Laya Heidari Darani

2015-05-01

Full Text Available It was claimed by variationists that languages experience variation at all levels, which is supposed to be patterned. The present study aimed at exploring how variation occurred in English and Persian wh-questions. More specifically, it investigated whether such a variation was systematic and patterned. To this end, a modified version of the Edinburgh Map Task was used in data collection. The population of this study was 60 Canadian and Persian native speakers who performed the task through the construction of wh-question variants. The results indicated that both languages experienced variation in the construction of wh-questions. However, Persian proved to be more variable than English because it allowed more wh-question variants to be produced. Moreover, this variation was patterned in English and Persian individually, yet a systematic variation could not be observed between these two languages. It followed that the different mind-sets of the Canadian and Iranian participants which were affected by social and cultural factors might account for such a variation.