5,283 research outputs found
Drag Reduction by Applying Speedstrips on Rowing Oars
No full textAbstractThe objective of this study was to determine the advantage of the application of speedstrips to rowing oars for a lightweight single sculler. The research method comprehended three steps: (1) the analysis of the rowing oar movement, (2) the determination of the change in drag and (3) the composition of a rowing model to establish the advantage that could be achieved. The parameters needed for the model: boat velocity, oar angle velocity and power delivered by the rower, were recorded on a real single sculler. The change in drag due to speedstrips on cylinders was determined by performing wind tunnel experiments. The rowing model (Matlab) simulates a race by using real stroke data of a world-class rower as input, while calculating the drag with the coefficients determined by the wind tunnel experiments. The output of the model is the final advantage by the application of speedstrips to rowing oars. Speedstrips induce a 0.1% advantage over a 2000 m race under calm wind conditions. The advantage increases up to .4% with a headwind velocity of 5 m s-1. For bigger boats, the advantage could be even more significant
Drag and Power-loss in Rowing Due to Velocity Fluctuations
No full textAbstractThe flow motions in the turbulent boundary layer between water and a rowing boat initiate a turbulent skin friction. Reducing this skin friction results in better rowing performances. A Taylor-Couette (TC) facility was used to verify the power losses due to velocity fluctuations PV′ in relation to the total power , as a function of the velocity amplitude A. It was demonstrated that an increase of the velocity fluctuations results in a tremendous decrease of the velocity efficiency eV . The velocity efficiency eV for a typical rowing velocity amplitude A of 20 – 25% was about 0.92 – 0.95%. Suppressing boat velocity fluctuations with 60% will increase boat speed with 1.6%. Riblet surfaces were applied on the inner and outer cylinder wall to indicate the drag reducing ability of such surfaces. The results of the measurements at constant velocity are identical as the results reported earlier, while the experimental configuration was different. This confirms once more the consistency of the TC-system for drag studies. The maximum drag reduction DR was 3.4% at a Reynolds number Res 4.7 × 104, which corresponds to a shear velocity in this TC-system with water of V 4.7 m/s. For typical rowing velocity fluctuations, the riblets maintain to reduce the drag with 2.8% and corresponds to a averaged velocity increase of 0.9%. The drag reducing ability of riblets is partly lost due to velocity fluctuations with high amplitudes (A > 20%). From these results, it is concluded that the friction coefficient Cf will vary within one cycle. Higher acceleration/deceleration leads to a additional level of turbulent kinetic energy
A.J. Cronin. A doctor into lifelong writer
No full textReality and fiction might be strictly coexistent in the narrative world. The author of this article, after a deep reading of A.J. Cronin’s novels, has tried to find out the right key to penetrate into the novelist’s intricate world. After many interrogatives on A.J. Cronin both as a man and writer, the author , finally, has been able to grasp from the pages of the novelist, the suffering of a man who has made of his romance the history of his own life
Conidial germination of Botryosphaeria dothidea Mough.: Fr (Ces. & De Not.) and histological alterations on stems of pitahaya (Hylocereus undatus H.) (Haworth) Britton & Rose [Germinación de conidios de Botryosphaeria dothidea Mough.: Fr (Ces. & De Not.) y alteraciones histológicas en tallos de pitahaya (Hylocereus undatus) (Haworth) Britton & Rose]
No full textConidial germination of Botryosphaeria dothidea (anamorph: Fusicoccum) in sterile distilled water and 1% sterile dextrose solution was evaluated at 4, 6, 12, 24 and 36 h after incubation. Also, it was described the anatomical changes on pitahaya stems induced by this fungus, collected in the field and artificially inoculated in the laboratory. Conidial germination was less than 30% in water and it was improved when 1% dextrose was added to the water. In 1% dextrose solution the germination was 90% after 4h of incubation and 100% at 6 h. Pathogen germ tubes had entered through wounds and sometimes through stomata and hyphae colonized intra and intercellularly in the parenchyma-chlorenchyma tissues. On naturally and artificially diseased stems the main alterations were: destruction of cuticle, hyperplasia of epidermal and collenchymatous hypodermal cells and conform the advance of the pathogen a layer of lignified periderm was formed surrounding the damaged tissues; however, it couldn't stop the advance of the pathogen and the cells that surrounded the lesion suffered necrosis
Conidial germination of Botryosphaeria dothidea Mough.: Fr (Ces. & De Not.) and histological alterations on stems of pitahaya (Hylocereus undatus H.) (Haworth) Britton & Rose [Germinaci�n de conidios de Botryosphaeria dothidea Mough.: Fr (Ces. & De Not.) y alteraciones histol�gicas en tallos de pitahaya (Hylocereus undatus) (Haworth) Britton & Rose]
No full textConidial germination of Botryosphaeria dothidea (anamorph: Fusicoccum) in sterile distilled water and 1% sterile dextrose solution was evaluated at 4, 6, 12, 24 and 36 h after incubation. Also, it was described the anatomical changes on pitahaya stems induced by this fungus, collected in the field and artificially inoculated in the laboratory. Conidial germination was less than 30% in water and it was improved when 1% dextrose was added to the water. In 1% dextrose solution the germination was 90% after 4h of incubation and 100% at 6 h. Pathogen germ tubes had entered through wounds and sometimes through stomata and hyphae colonized intra and intercellularly in the parenchyma-chlorenchyma tissues. On naturally and artificially diseased stems the main alterations were: destruction of cuticle, hyperplasia of epidermal and collenchymatous hypodermal cells and conform the advance of the pathogen a layer of lignified periderm was formed surrounding the damaged tissues; however, it couldn't stop the advance of the pathogen and the cells that surrounded the lesion suffered necrosis
Frequency and behavior of salmonella and escherichia coli on whole and sliced jalapeño and serrano peppers
No full textGladiolus rust, caused by Uromyces transversalis, is a quarantinesignificant pathogen in the United States. However, the fungus is endemic to commercial gladiolus-producing areas in Mexico and has been intercepted frequently on gladiolus plants entering the United States for the cut-flower market. The present study assessed 15 fungicide active ingredients (five quinone outside inhibitors: azoxystrobin, fluoxastrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin; six triazoles: cyproconazole, difenoconazole, epoxiconazole, myclobutanil, propiconazole, and tebuconazole; three succinate dehydrogenase inhibitors: boscalid, flutolanil, and oxycarboxin; and one broad-spectrum protectant: chlorothalonil) and one plant activator, acibenzolar-S-methyl, applied alone, in combinations, and in various rotations for efficacy against U. transversalis on field-grown gladiolus plants in Mexico. Experiments were conducted in 2010, 2011, and 2012 in commercial fields in Atlixco and Santa Isabel Cholula in Puebla and Cuautla and Tlayacapan in Morelos. Fungicides were applied at 2-week intervals starting when plants had three full leaves. Disease severity was recorded each week for at least 7 weeks after the first application. Under high disease pressure in 2010, fungicides were less effective than in 2011 and 2012, when disease pressure was not as high. In all 3 years, most fungicide treatments significantly reduced disease severity. Triazoles were more effective than quinone outside inhibitors when applied as individual products in 2010, and combinations of two fungicides in different mode-of-action groups were more effective than fungicides applied individually in 2011. In 2012, rotations of fungicides, either with individual products or with combinations of two products, provided excellent rust management. Reducing disease development by U. transversalis on commercial gladiolus plants in Mexico will reduce the potential for introducing this pathogen on cut flowers into the United States. " 2013 The American Phytopathological Society.",,,,,,"10.1094/PDIS-03-13-0272-RE",,,"http://hdl.handle.net/20.500.12104/41634","http://www.scopus.com/inward/record.url?eid=2-s2.0-84885439680&partnerID=40&md5=c22c18ae5d42a9e893886ada7c390aa4",,,,,,"11",,"Plant Disease",,"149
Fungicides used alone, in combinations, and in rotations for managing gladiolus rust in Mexico
No full textGladiolus rust, caused by Uromyces transversalis, is a quarantinesignificant pathogen in the United States. However, the fungus is endemic to commercial gladiolus-producing areas in Mexico and has been intercepted frequently on gladiolus plants entering the United States for the cut-flower market. The present study assessed 15 fungicide active ingredients (five quinone outside inhibitors: azoxystrobin, fluoxastrobin, kresoxim-methyl, pyraclostrobin, and trifloxystrobin; six triazoles: cyproconazole, difenoconazole, epoxiconazole, myclobutanil, propiconazole, and tebuconazole; three succinate dehydrogenase inhibitors: boscalid, flutolanil, and oxycarboxin; and one broad-spectrum protectant: chlorothalonil) and one plant activator, acibenzolar-S-methyl, applied alone, in combinations, and in various rotations for efficacy against U. transversalis on field-grown gladiolus plants in Mexico. Experiments were conducted in 2010, 2011, and 2012 in commercial fields in Atlixco and Santa Isabel Cholula in Puebla and Cuautla and Tlayacapan in Morelos. Fungicides were applied at 2-week intervals starting when plants had three full leaves. Disease severity was recorded each week for at least 7 weeks after the first application. Under high disease pressure in 2010, fungicides were less effective than in 2011 and 2012, when disease pressure was not as high. In all 3 years, most fungicide treatments significantly reduced disease severity. Triazoles were more effective than quinone outside inhibitors when applied as individual products in 2010, and combinations of two fungicides in different mode-of-action groups were more effective than fungicides applied individually in 2011. In 2012, rotations of fungicides, either with individual products or with combinations of two products, provided excellent rust management. Reducing disease development by U. transversalis on commercial gladiolus plants in Mexico will reduce the potential for introducing this pathogen on cut flowers into the United States. © 2013 The American Phytopathological Society
A brief overview on pitahaya (Hylocereus spp.) diseases
No full textThe objective of this contribution is to present some recent advances in research on the diseases affecting pitahaya (Hylocereus spp.) conducted in various parts of the world, thereby providing some information for promoting further studies on plant protection of the pitahaya species. Pitahaya is a cactus fruit crop of high demand at national and international level. It is cultivated in more than ten countries worldwide. Prevalent form of cultivation until little more than 20 years was in small-scale family production. However, since its cultivation in commercial plantations and further domestication started in earnest, some symptoms of rottening and spots in stems and fruits were being observed. In some cases, commercial production plots had to be abandoned due to the diseases. In the decade of 1990s in Mexico, some studies on stem soft rot disease were initiated. It was found that at least two Enterobacteria were involved. With regard to the causal agent of the spots on stems, it was identified as a fungus specie, Botryosphaeria dothidea Ces. & De Not, anamorph Fusicoccum sp. Morphological and physiological characterization were made in Mexico, so as to develop integrated management strategies. Anthracnose is yet another fungal disease that could become aggressive as it affects fruits and stems. Etiological studies in USA and Japan revealed the causal agent to be a fungus Colletotrichum gloesporioides Penz. Meanwhile, researchers in Taiwan described some morphological and genomic characteristics of a virus, Cactus Virus X. This virus causes a kind of mosaic on the stem, a mixture of light and dark green areas. Perspective of pitahaya as a commercial crop is promising. In terms of crop protection, however, it is necessary to determine genetic diversity of plant pathogen species as well as that of the causal agents and to develop integrated control measures. Moreover, few studies were made on the diseases in post-harvest. The viral disease is not yet to be reported in Mexico, but some personal observations appear to indicate that it is already present in commercial plantations in the country. It is thus imperative to initiate sampling, detection, and identification activities using traditional and molecular techniques. The final objective of all aforementioned aspects is to conserve and successfully manage pitahaya resource. � 2012 Australasian Plant Pathology Society Inc
Herbicide evaluation to control weeds in irrigated chickpea (Cicer rietinum L.) at the region Ciénega of Chapala, México [Evaluación de herbicidas para el control de malezas en garbanzo cicer arietinum L.) de riego en la región ciénega de chapala, méxico]
No full textUse of herbicides to control weeds is an available option in irrigated chickpea crop at the region Cienega of Chapala, Jalisco State, Mexico. In this work five herbicides: alachlor, oxyfluorfen, pendimethalin, prometryn and trifluralin were evaluated and applied in pre-emergenge in order to know their control on the broadleaf weeds species Amaranthus sp., Chenopodium spp., Portulaca oleracea, Physalis costomati and Euphorbia heterophylla in kabuli chickpea (Cicer arietinum L.) under irrigation conditions during the seasons 2003-04 and 2004-05. Treatments were tested in a randomized complete block design with four replications; plot size consisted on four rows 5 meters long and 76 cm between rows. For each herbicide was calculated the percentage of each weed control. For each weed carried out analysis of variance and the Tukey test. Statistical differences among herbicides treatments over the weed species were found, both different percentages of control. The most effective herbicides were Pendimethalin 3.5 L.ha -1 and Trifluralin 3.5 L.ha -1, with percentages of control from 77 to 95. There were not toxicity by herbicides on chickpea crop
Computing with cables: Towards massively parallel neuro computers
No full textElectrical Engineering, Mathematics and Computer Scienc
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