339 research outputs found
Effects of Ozone Exposure on Resistance of Wheat Genotypes to Pyrenophora tritici‐repentis
No full textThree spring wheat genotypes, susceptible, moderately resistant or resistant to Pyrenophora tritici‐repentis (tan spot fungus) were exposed to charcoal‐filtered air and to approx. 80, 160, 240 (g m−3 ozone for five consecutive days (7 h per day). Visible leaf injury on seedling plants (three‐leaf stage) was only observed after fumigation with 160 or 240 (g m−3 O3. Amount of injury was four‐fold and 10‐fold on the susceptible genotype when compared to resistant or moderately resistant genotype at the two highest concentration of ozone, respectively. Genotypic differences to O3 tolerance were detected at the seedling growth stage (three‐leaf stage) and flowering stage but not at the stem elongation stage. A significant increase in tan spot lesion area was observed only on O3 predisposed second top most leaves of the susceptible genotype at all the three levels of ozone. Predisposition did not enhance tan spot development in resistant and moderately resistant genotypes. In a test with 12 wheat genotypes, a highly significant positive correlation (r = 0· 986, p < 0· 0001) was observed between ozone sensitivity (percent leaf area damaged due to 240 (g m−3 ozone exposure) and tan spot development (mm2 lesion area) following inoculation with P. tritici‐repentis. It indicates that wheat genotypes resistant to the tan spot fungus might be tolerant to ozone damage
Natural occurrence of mycotoxins in staple cereals from Ethiopia
No full textThe occurrence of mycotoxins in barley, sorghum, teff (Eragrostis tef) and wheat from Ethiopia has been studied. Samples were analyzed for aflatoxin B-1 (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) using high performance liquid chromatography (HPLC) and for fumonisins (FUM) using enzyme linked immunosorbent assay (ELISA). AFB1 and OTA were detected in samples of all the four crops. AFB1 was detected in 8.8% of the 352 samples analyzed at concentrations ranging from trace to 26 mu g kg(-1). OTA occurred in 24.3% of 321 samples at a mean concentration of 54.1 mu g kg(-1) and a maximum of 2106 mu g kg(-1). DON occurred in barley, sorghum and wheat at 40-2340 mu g kg(-1) with an overall incidence of 48.8% among the 84 mainly 'suspect' samples analyzed; NIV was co-analyzed with DON and was detected at 40 mu g kg(-1) in a wheat sample and at 50, 380, and 490 mu g kg(-1) in three sorghum samples. FUM and ZEN occurred only in sorghum samples with low frequencies at concentrations reaching 2117 and 32 mu g kg(-1), respectively. The analytical results indicate higher mycotoxin contamination in sorghum, which could be related to the widespread storage of sorghum grain in underground pits leading to elevated seed moisture contents. This is the first report on the occurrence of OTA in teff
Ozone episodes in southern lower saxony (FRG) and their impact on the susceptibility of cereals to fungal pathogens
No full textSpring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) plants were exposed to simulated ozone (O3) episodes (7 h day−1 for 7 days) at maximum concentrations of 120, 180 and 240 μg m−3 O3, in comparison to a charcoal-filtered air control. Fumigations were conducted in four closed chambers placed in a climate room. Exposures took place prior to inoculation of the plants with six different facultative leaf pathogens. On wheat, significant enhancement of leaf attack by Septoria nodorum Berk. and S. tritici Rob. ex Desm. appeared, particularly on the older leaves and at the highest level of O3. The same was true for Gerlachia nivalis W. Gams et E. Müll/Fusarium culmorum (W.F.Sm.) Sacc. on wheat and net blotch (Drechslera teres (Sacc.) Shoem.) or G. nivalis leaf spots on barley. Disease development was promoted both on leaves with and without visible injury following exposure to O3. Sporulation of the two Septoria species increased at 120 and 180 μg m−3 O3; however, it was reduced to the level of the control, if 240 μg m−3 were applied. No significant effects of predisposition were observed with Bipolaris sorokiniana (Sacc.) Shoem. (syn. Helminthosporium sativum Pamm., King et Bakke), the causal agent of spot blotch, neither on wheat nor on barley. Doses and peak concentrations applied in the experiments were in good agreement with measurements of ambient ozone in Southern Lower Saxony, FRG. Six years' ozone data (1984–1989) revealed the annual occurrence of between 3 and 11 ozone episodes with potentially harmful effects on cereals (three or more consecutive ‘ozone days’ with 8-h means above 80 μg m−3). The frequency of ozone episodes followed by weather periods favourable for infections by facultative pathogens was higher in years with low O3 pollution than in ozone-rich years, and varied between one and five cases per season. The number of ozone days during the main growing season of cereals (1 April until 31 August) varied from 25 in 1984 to 98 in 1989. However, only 7·9% of ozone days during the 6 years examined were concurrent with weather conditions suitable for fungal infections. It is concluded that the majority of leaf infections in the field happens under low-level concentrations of photooxidants
Fritz Schumacher & Heinrich Tessenow: Architecture, an Art or a Craft?
No full textThis booklet contains the inaugural lectures of Fritz Schumacher and Heinrich Tessenow given on the occasion of their appointment respectively as professors at the Technical University in Dresden and The Art Academy in Dresden.The lectures provide novel insights into their understanding of architecture and into their proposals for reform of architectural education. they are proceeded by an introductory essay of the guest editor architectural historian Hartmut Frank.History, Form & Aesthetic
Sociedades modernas, sociedades de obsolescência: a sociologia temporal de Hartmut Rosa / Modern societies, obsolescence societies: Hartmut Rosa's temporal sociology
No full textResenha de: ROSA, Hartmut. Aceleração: a transformação das estruturas temporais na modernidade. São Paulo: Editora Unesp, 2019. Centrado na revisitação da modernidade a partir de uma perspectiva temporal, Hartmut Rosa sustenta o conceito de aceleração social como aspecto fundante do projeto moderno. Explorando diferentes variáveis causais para o conceito da aceleração social, a resenha examina as transformações das instituições morais, valorativas e políticas ocorridas ao longo do desenvolvimento histórico da modernidade como episódios induzidos pela obsolescência. Sendo esta um produto de campos de ação crescentemente cambiantes e acelerados, o autor mobiliza esse conceito para fundamentar inédita proposta de diferenciação entre a modernidade e a modernidade tardia como momentos históricos calcados em diferentes níveis de compressão espaço-temporal, estabilidade institucional e temporalização de projetos individuais e coletivos de futuro.***AbstractCentered on revisiting modernity from a temporal perspective, Hartmut Rosa supports the concept of social acceleration as a fundamental aspect of the modern project. Exploring different causal variables for the concept of social acceleration, the review examines the transformations of moral, valuative and political institutions that occurred during the historical development of modernity as episodes induced by obsolescence. As this is a product of increasingly changing and accelerated fields of action, the author mobilizes this concept to substantiate an unprecedented proposal for differentiation between modernity and late modernity as historical moments based on different levels of space-time compression, institutional stability and temporalization of individual and collective future projects
Surveying silk fibre degradation by crystallinity determination: a study on the Tang-Dynasty silk treasure from Famen Temple, China
No full textWhen Chinese archaeologists opened an unknown vault under the collapsed pagoda of Famen Temple near Xian (Shaanxi Province, NW China) in 1987, they found a vast amount of valuable silk textiles. The degraded textiles were part of a treasure comprising hundreds of artifacts deposited by Tang dynasty (ad 618–907) emperors as a gift to the temple. Run as a bilateral German-Chinese project, the Roemisch-Germanisches Zentralmuseum Mainz established a textile conservation laboratory in Shaanxi´s provincial capital Xian in 2001, joining numerous other laboratories that have existed there since the early 1990s.This preliminary study represents part of an ongoing investigation programme that accompanies the conservation work. The Tang dynasty silk is generally in a very poor state of preservation as a result of its long burial period. Large sections have only survived as an amorphous brown mass of fibre debris. Some parts are better preserved, however, offering the unique opportunity to study the whole range of degradation stages on ancient silks.This preliminary scientific investigation focuses on the determination of the silk fibres’ crystallinity and its relation to the ageing process. As we know from modern material, silk is mainly crystalline, albeit in a somewhat amorphous state. The methods of investigation used were X-ray diffraction (XRD) using synchrotron radiation, which is a new way to determine crystallinity of ancient silk fibres; and polarized Fourier transform infrared spectroscopy (FTIR) for the determination of crystallite orientation. Both methods were specifically devised to gain information on small single fibres
Bekämpfung der Halmbruchkrankheit des Weizens mit Benomyl
No full text1. Ergebnisse mehrjähriger Untersuchungen zeigten, daß das Ausmaß der Herbstinfektionen von Winterweizen durch Cercosporella herpotrichoides um so größer ist, je häufiger in der Fruchtfolge Weizen direkt nach Weizen angebaut wird. Das Ausmaß äer Frühjahrsinfektionen ist weniger fruchtfolgeabhängig.
2. In einem Freilandversuch in einem Winterweizenfeld mit zeitlich gestaffelten Spritzungen mit Du Pont Benomyl erwies sich alleinige Herbstapplikation des Mittels - gemessen am Cercosporella-Befall 6 Wochen vor der Ernte - als relativ wirkungslos. Durch Frühjahrsspritzungen konnte die Halmbruchkrankheit dagegen sehr gut unter Kontrolle gebracht werden. Die Anwendung des Fungizids war dabei um so wirkungsvoller, je später sie erfolgte. Die letzte und erfolgreichste Spritzung wurde Mitte Mai vorgenommen. In den günstigsten Fällen konnte der Prozentsatz kranker Halme auf 7-10 % gegenüber 95 0/o in der ungespritzten Kontrolle gesenkt werden.
3. Gewächshausversuche demonstrierten die sehr gute kurative Wirkung von Benomyl gegenüber Cercosporella herpotrichoides. Durch Applikation 24 bis 39 Tage nach der künstlichen Infektion von Weizenpflanzen konnte die Entwicklung der Halmbruchkrankheit sehr gut unterdrückt werden. Zeitlich gestaffelte, präinfektionelle Spritzungen hatten dagegen nur dann guten Erfolg, wenn das Mittel weniger als 10 Tage vor der Infektion eingesetzt wurde.
4. Die praktische Bedeutung der mitgeteilten Ergebnisse wird diskutiert. Es erscheint empfehlenswert, die Einsatzmöglichkeit von Benomyl gegen Cercosporella in größerem Rahmen zu prüfen.1. From field experiments during several years it became evident, that infections of winter wheat by Cercosporella herpotrichoides in autumn are the more numerous, the more often wheat is directly followed by wheat in the crop rotation. The degree of infections in spring is less dependent on the crop rotation.
2. In one field experiment with winter wheat application of Du Pont Benomyl (Benlate) solely in autumn was relatively inefficient in controlling the eyespot-disease - as measured by the incidence with Cercosporella six weeks before harvest. On the other hand, sprayings in spring proved to be very successful. Application of the fungicide was the more efficient, the later it took place. The last spraying in May was the most successful one. It was possible to reduce the percentage of diseased plants from 95 percent in the check to 7 to 10 percent.
3. Greenhouse experiments demonstrated the very good curative effect of Benomyl against Cercosporella herpotrichoides. Application 24-39 days after artificial infection was optimal in suppressing the development of the eyespot- disease. Preinfectional sprayings rendered only good success, when the fungicide was applied less than 10 days before infection.
4. The practical importance of the reported findings is discussed. It is recommended to check the possibilities of controlling Cercosporella herpotrichoides by Benomyl on a broader scale
Modernidade dessincronizada: aceleração social, destemporalização e alienação: uma entrevista com Hartmut Rosa
No full textThe scope of this interview is to present the social experiences and the analytical categories which comprise Hartmut Rosa’s theory of social acceleration. At the outset, the questions lead the author to recall the reasons that lead to his interest in the problem of time in the present modernity, as well as the intellectual path that guided him to such an interest. The consequences of what Rosa diagnoses as a society of de-synchronized and de-temporalized acceleration are exposed and subsequently a new interpretation of the concept of alienation is proposed. Through his claim of being a successor to the school of critical social theory, Rosa also indicates the rough outlines of his critical model’s normative referential, examining the temporal maxims that make up the modern ideal of a good life.A presente entrevista traz como seu escopo uma apresentação da experiência social e das principais categorias analíticas que compõem a teoria da aceleração social de Hartmut Rosa. De início, as questões conduzem o autor a uma recapitulação dos motivos que o levaram a desenvolver seu interesse pelo problema do tempo na modernidade hodierna, bem como da trajetória intelectual que o guiou a tal interesse. São expostas as consequências daquilo que Rosa diagnostica como uma sociedade de aceleração dessincronizada e destemporalizada, e, com elas, uma nova interpretação do fenômeno da alienação. Reivindicando-se como um herdeiro da teoria crítica da sociedade, Rosa também indica os traços gerais do referencial normativo de seu modelo crítico, examinando as máximas temporais que perfazem o ideal moderno de boa vida
Ultrastruktur von Weizenkoleoptilzellen nach Infektion mit Cercosporella herpotrichoides
No full textÜber Ergebnisse lichtmikroskopischer Untersuchungen zur Pathogenese der durch den Pilz Cercosporella herpotrichoides Fron (syn. Pseudocercosporella herpotrichoides, gen. nov., DEIGHTON 1973) hervorgerufenen Halmbruchkrankheit des Getreides wurde bereits häufig in der Literatur berichtet (FRON 1912, FoEX und ROSELLA 1930, SCHAFFNIT 1933, SPRAGUE und FELLOWS 1934, LANGE OE LA CAMP 1966, DEFOSSE 1966, 1967, 1971 u. a.). In den meisten Fällen galt das Hauptinteresse der Autoren dem Infektionsvorgang. Bislang liegen noch keine Publikationen zu der Frage vor, wie sich der Feinbau der Wirtszellen während der Pathogenese verändert. Diesem Problemkreis waren eigene elektronenmikroskopische Untersuchungen gewidmet, über deren Resultate nachfolgend berichtet wird. Als Arbeitscbjekt wurden junge infizierte Weizenkoleoptilen gewählt.publishe
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