Academic literature on the topic 'Dry covers'
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Journal articles on the topic "Dry covers"
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Ibarra-Jiménez, L., J. Munguía-López, A. J. Lozano-del Río, and A. Zermeño-González. "Effect of plastic mulch and row covers on photosynthesis and yield of watermelon." Australian Journal of Experimental Agriculture 45, no. 12 (2005): 1653. http://dx.doi.org/10.1071/ea04140.
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The effect of row covers on watermelon (Citrullus vulgaris) grown on plastic mulch is well documented. However, row covers have not been adequately evaluated under Mexican growing conditions. Watermelon plants were grown on plastic mulch alone or with row covers to study their effect on photosynthesis, and early and total yields. Treatments were clear plastic mulch (C); black plastic mulch (B); B plus a Vispore cover of polypropylene (BV); B plus a white cover of perforated polyethylene (BW); B plus a clear cover of perforated polyethylene (BC); B plus an Agribon cover of polypropylene (BA); and bare soil as the control. For plants grown in treatment C, B or B combined with row covers, plant dry weight and number of leaves 40 days after seeding (DAS) were higher than the control (P<0.05), except BC which was comparable to the control. Total yields of treatments C, B, BV, BW and BA differed (P<0.05) from BC and the control. Total yields increased by 46.1, 43.2, 35.7, 41.6, 13.3, 15.4 and 35.8 t/ha for the C, B, BV, BW, BC and BA treatments, respectively, over the control, which yielded 27.1 t/ha. Total yield was highest for the C and the B treatment suggesting that there was no need for additional covers. The number of leaves per plant or dry weight per plant better explains the changes in yield than net photosynthesis rate. Stomatal conductance was explained in part by changes in photosynthesis.
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Ibarra-Jiménez, L., M. R. Quezada-Martín, and M. de la Rosa-Ibarra. "The effect of plastic mulch and row covers on the growth and physiology of cucumber." Australian Journal of Experimental Agriculture 44, no. 1 (2004): 91. http://dx.doi.org/10.1071/ea02088.
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To determine the effectiveness of black plastic mulch alone and in combination with row covers, on growth and physiological changes of cucumber plants, 6 treatments were established in a randomised complete block design with 4 replications: bare soil (control); black polyethylene mulch alone (B); B plus a clear cover of perforated polyethylene (BRCP); B plus a white cover of perforated polyethylene (BRWP); B plus an Agribon cover of polypropylene (BRA); and B plus a Kimberly farm row cover (BRK). For the plants grown with mulch or mulch combined with row covers, the dry weight of leaves 50 days after seeding (DAS), and the dry weight of whole plants (at 50 and 110 DAS) were significantly (P<0.05) different from the control. Early yields of treatments B, BRCP, BRWP, BRA and BRK were 2.1, 1.9, 2.6, 1.9 and 2.4 times higher than the control, which yielded 10 t/ha. Total yields were increased by 9.7, 15.4, 19.8, 14.9 and 20 t/ha, over the control which yielded 104 t/ha. Increases in plant dry weight explained the changes in yield. Stomatal conductance may explain in part, the increase in photosynthetic rate, but may not explain yield increase.
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Stang, Elden J., and John Klueh. "SPUNBONDED FABRIC COVERS ALTER EARLY SEASON GROWTH AND FRUIT SET IN CRANBERRY." HortScience 25, no. 9 (September 1990): 1105c—1105. http://dx.doi.org/10.21273/hortsci.25.9.1105c.
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Spunbonded polypropylene fabric covers were applied over mature `Searles' cranberry (Vaccinium macrocarpon Ait. in the field during dormancy in 1989. Covers were selectively removed at 3 week intervals in April, May and early June after onset of growth. Plant canopy air temperatures under fabric were 5 to 6C higher than in exposed controls. Temperature differences up to 17C were measured in early June. Soil temperatures did not differ from the control until late May. Earlier greening of leaf tissue resulted in increased photosynthetic rates earlier in the growing season under fabric covers. Subsequent shoot dry weight was increased 5%; leaf size was not affected. A trend to increased fruit set (4 to 6%) with fabric cover treatments was observed when covers were applied for 6 or 9 weeks. Total fruit yield and anthocyanin content were not appreciably influenced by fabric covers.
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Dieser, Markus, Andreas Nocker, John C. Priscu, and Christine M. Foreman. "Viable microbes in ice: application of molecular assays to McMurdo Dry Valley lake ice communities." Antarctic Science 22, no. 5 (June 23, 2010): 470–76. http://dx.doi.org/10.1017/s0954102010000404.
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AbstractThe permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) to examine membrane integrity of prokaryotes in these extreme environments. PMA selectively penetrates cells with compromised membranes and modifies their DNA resulting in the suppression of PCR amplification. Our results based on analysis of 16S rRNA genes demonstrate that despite the hostile conditions of the Dry Valleys, the permanent ice covers of the lakes support a ‘potentially viable’ microbial community. The level of membrane integrity, as well as diversity, was higher in samples where sediment was entrapped in the ice cover. Pronounced differences in the fraction of cells with intact and compromised cell membranes were found for Lake Fryxell and east lobe of Lake Bonney, both expressed in differences in DGGE banding patterns and qPCR signal reductions. Limitations in the ability to distinguish between intact or compromised cells occurred in samples from Lake Hoare and west lobe of Lake Bonney due to low DNA template concentrations recovered from the samples.
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Mylona, Evangelia, Anthimos Xenidis, Mihály Csövári, and Gábor Németh. "Application of dry covers for the closure of tailings facilities." Land Contamination & Reclamation 15, no. 2 (April 1, 2007): 163–82. http://dx.doi.org/10.2462/09670513.849.
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Jiménez-Rodríguez, César, Catalina Esquivel-Vargas, Miriam Coenders-Gerrits, and Mahmood Sasa-Marín. "Quantification of the Evaporation Rates from Six Types of Wetland Cover in Palo Verde National Park, Costa Rica." Water 11, no. 4 (April 1, 2019): 674. http://dx.doi.org/10.3390/w11040674.
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The hydrology of tropical seasonal wetlands is affected by changes in the land cover. Changes from open water towards a vegetated cover imply an increase in the total evaporation flux, which includes the evaporation from open water bodies and the transpiration from vegetated surfaces. This study quantified the total evaporation flux of six covers of the Palo Verde wetland during dry season. The selected wetland covers were dominated by Neptunia natans (L.f.) Druce, Thalia geniculata L., Typha dominguensis Pers., Eichhornia crassipes (Mart.) Solms, a mixture of these species, and open water conditions. The plants were collected from the wetland and placed in lysimeters (59.1 L) built from plastic containers. The lysimeters were located in an open area near the meteorological station of the Organization for Tropical Studies (OTS). The evaporated water volume and meteorological data were collected between December 2012–January 2013. A completely randomized design was applied to determine the total evaporation (E), reference evaporation ( E ref , Penman-Monteith method) and crop coefficient ( K c ) for all the covers. T. geniculata (E: 17.0 mm d − 1 , K c : 3.43) and open water (E: 8.2 mm d − 1 , K c : 1.65) showed the highest and lowest values respectively, for daily evaporation and crop coefficient. Results from the ANOVA indicate that E. crassipes and N. natans were statistically different (p = 0.05) from T. dominguensis and the species mixture, while the water and T. geniculata showed significant differences with regard to other plant covers. These results indicate that the presence of emergent macrophytes as T. geniculata and T. dominguensis will increase the evaporation flux during dry season more than the floating macrophytes or open water surfaces.
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Germer, Jörn. "Effect of transparent covers for collection chambers of urine-diverting dry toilets on dehydration of faecal waste." Journal of Water, Sanitation and Hygiene for Development 1, no. 3 (September 1, 2011): 195–203. http://dx.doi.org/10.2166/washdev.2011.032.
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Urine-diverting dry toilets save water, reduce the demand for wastewater treatment and provide plant nutrients. The conditions in the collection chambers and the interlinked hygienic safety of subsequent faecal matter use in crop production are affected by the building design. Comparative experiments were carried out to evaluate the potential of transparent chamber covers in comparison with non-transparent chamber covers to increase temperature and ventilation in order to enhance faecal matter dehydration and sanitation. The air temperature in the chambers with transparent covers (TC) was 1.1–1.5 °C higher and the relative air humidity about 5–7% lower than in chambers with non-transparent covers. The advantage of TCs on temperature and humidity prevailed throughout the year, but was most pronounced in months with more sunshine hours and higher irradiation. Furthermore, the airflow out of the chambers through the ventilation pipes was increased by 60% in the TCs. During two-month collection and dehydration cycles the improved drying conditions in the TCs resulted in 7% lower faecal matter moisture. A trend towards an enhanced pathogen inactivation in the faecal material was observed. The results demonstrate that in the semi-arid tropics transparent covers for collection chamber of urine diverting dry toilets improve the dehydration of faecal matter.
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Casierra-Posada, Fánor, Esteban Zapata-Casierra, and Daniel A. Chaparro-Chaparro. "Growth analysis in chard plants (Beta vulgaris L. Cicla, cv. 'Pencas Blancas') exposed to different light quality." Agronomía Colombiana 32, no. 2 (May 1, 2014): 205–12. http://dx.doi.org/10.15446/agron.colomb.v32n2.42640.
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To determine the effects of light quality on the growth indices of plants, Pencas Blancas cultivar chard plantlets were grown for 2 months under five different light treatments, obtained by filtering sunlight through colored polyethylene films. The treatments included: red, blue, green, yellow and transparent cover colors. A transparent cover (white light) was used as the control. The colored covers affected the plant growth. The plants grown under the yellow cover presented a better behavior with regards to growth, taken as: total dry weight per plant, leaf area, specific leaf area, absolute growth rate, relative growth rate, harvestable dry matter and root to shoot ratio. The dry matter partitioning in the leaves and roots was affected by the light quality, but not in the petioles, with a higher accumulation of dry mass in the leaves of plants grown under the yellow cover. As a consequence of the enhanced leaf area in the plants under the yellow cover, they also had the highest water uptake. On the other hand, the highest net assimilation rate value was found in plants grown under the transparent cover. These results open up the possibility of using yellow colored cover in leafy green vegetables, especially in chard plants grown under controlled conditions.
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Calheiros, Altanys Silva, Mario de Andrade Lira Junior, Mércia Virgínia Ferreira Santos, and Maria do Carmo Catanho Pereira Lyra. "SYMBIOTIC EFFECTIVENESS AND COMPETITIVENESS OF CALOPO RHIZOBIAL ISOLATES IN AN ARGISSOLO VERMELHO-AMARELO UNDER THREE VEGETATION COVERS IN THE DRY FOREST ZONE OF PERNAMBUCO." Revista Brasileira de Ciência do Solo 39, no. 2 (April 2015): 367–76. http://dx.doi.org/10.1590/01000683rbcs20140393.
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Biological N fixation in forage legumes is an important alternative to reduce pasture degradation, and is strongly influenced by the inoculant symbiotic capability. This paper evaluates the effectiveness of Calopo (Calopogonium mucunoides) rhizobial isolated from soil under three vegetation covers of an Argissolo Vermelho-Amarelo of the Dry Forest Zone of Pernambuco. An experiment was conducted evaluating 25 isolates, aside from 5 uninoculated controls with 0; 309; 60; 90 and 120 kg ha-1 N, and a treatment inoculated with the SEMIA 6152 strain. The first cut was performed 45 days after inoculation and a second and third cut after 45-day-intervals. Shoot N content was quantified at all cuts. Shoot dry mass was affected by N rates at all cuts. Shoot dry mass increased from the first to the second cut in inoculated plants. There was no difference between rhizobial isolates from the different plant covers for any of the variables. Most variables were significantly and positively correlated.
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Henderson-Cole, Janet C., and Michael A. Schnelle. "Effect of Prodiamine and Oxadiazon on Growth of Bedding Plants and Ground Covers." Journal of Environmental Horticulture 11, no. 1 (March 1, 1993): 17–19. http://dx.doi.org/10.24266/0738-2898-11.1.17.
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Abstract Four bedding plant species, rose periwinkle, petunia, geranium, and scarlet salvia; four ground cover cultivars, golden Japanese barberry, common periwinkle, Bowles periwinkle, and greater periwinkle; and pots seeded with two weed species, crabgrass or pigweed were sprayed with 0, 1.1 or 4.5 kg ai/ha (0, 1.0 or 4.0 lb/A) prodiamine (Barricade) or 2.2 kg ai/ha (2.0 lb/A) oxadiazon (Ronstar). Heights or dry weights or both of all bedding plant species decreased linearly with increasing prodiamine (Barricade) application rates. Ground covers were not affected by oxadiazon (Ronstar) or prodiamine (Barricade) except for a reduction in root dry weight of common periwinkle with prodiamine (Barricade) applications. Crabgrass and pigweed were completely controlled by prodiamine (Barricade) throughout the growing season, but oxadiazon (Ronstar) lost its effectiveness after three months.
Dissertations / Theses on the topic "Dry covers"
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Mya, Thandar Toe. "RAINFALL VARIABILITY, LAND COVER DYNAMICS AND LOCAL LIVELIHOOD IN DRY ZONE, CENTRAL MYANMAR." Kyoto University, 2016. http://hdl.handle.net/2433/215601.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19775号
農博第2171号
新制||農||1041(附属図書館)
学位論文||H28||N4991(農学部図書室)
32811
京都大学大学院農学研究科森林科学専攻
(主査)教授 神﨑 護, 教授 柴田 昌三, 教授 大澤 晃, 外国人教師 鄭 克聲
学位規則第4条第1項該当
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Gran, Esforzado Meritxell. "Coupled heat and water flow dynamics in dry soils : application to a multilayer waste cover." Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/299535.
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Unsaturated flow plays an important role in numerous environmental phenomena. It is complex in arid regions, where liquid water fluxes are small and vapor fluxes become relevant, so that heat, water and solute mass transport are needed to understand evaporation. This thesis aims at gaining insight evaporation and vapor flow mechanisms and the relevance of matric potential, temperature and osmotic gradients.
These issues are especially relevant for soil salinization, whose mechanisms are poorly understood despite their global impact. We studied them in open soil evaporation column experiments. We found that a water separation process occurs in the soil. Above a very narrow evaporation front, the soil contains high salt concentrations due the solutes transported by the upward liquid flux and concentrated by evaporation. Below, concentrations are lower than the initial ones, because vapor flows downwards below the evaporation front driven by temperature gradients. Condensation of this downward vapor flux dilutes upflowing water, improving soil conditions and providing an area where root plants could live.
We modeled nonisothermal multiphase flow and reactive transport during the experiments to quantify the actual processes and to understand the nature of the downward vapor flux. Modeling required modifying the retention curve to represent oven dry conditions. Our model supports the traditional division of soil, by an evaporation front, into a dry region and a moist region. This view may suffice for evaluating evaporation rates and water mass balances, but not for assessing salt processes, which require acknowledging that not only liquid water flow but also vapor diffusion occur below the evaporation front.
Unsaturated flow concepts control the design of covers to isolate solid waste. Their goal is to protect the waste from infiltration during long periods of time by promoting surface runoff and lateral drainage and by hindering biointrusion. Two cover designs were built, both consisting of an evapotranspiration layer, a biointrusion barrier and an infiltration barrier. We analyzed their performance for two years (2009 and 2010, which was very wet) by a thorough monitoring system. We conclude that the upper portion of one cover did work as planned, but the lower infiltration barrier did not, which suggests some design improvements: increase the retention capacity of the sand layers, include filter layers and facilitate lateral drainage by increasing the slope in the top area.
We studied the daily and annual variations of vapor fluxes using data from the covers. We find that most water flow in the top portion of the soil occurs in the gas phase. Vapor fluxes are controlled by temperature and follow its fluctuations, switching direction with a daily frequency and a depth dependent lag. Downward vapor fluxes are dominant during the summer and upward fluxes during the winter. Deeper into the soil, vapor fluxes vary seasonally, flowing almost constantly upwards during the cold season, and vice versa. Rainfall events have a cooling effect, reversing summer vapor fluxes. Yet, the net annual flux is downwards. Furthermore, an approximate analytical solution to calculate diffusive vapor fluxes at any depth, is presented. While vapor fluxes are quantitatively small, they may still represent a significant source of water during summer for shallow roots. Plants may attract water from hot zones around to the root zone, kept colder by the plant shadow and by transpiration.
Numerical modeling is also used to simulate one of the covers. Model output is compared to observations (suction and temperature), which are well reproduced in the top soil layers. The model does not reproduce the failure of the capillary barrier because it did not include gravity fingering, which explains flow through the coarse layer.La zona no saturada juga un paper important en nombrosos fenòmens ambientals. És complex en zones àrides, on els fluxos d'aigua líquida són petits i els fluxos de vapor adquireixen rellevància. El transport de calor, d'aigua i de soluts és necessari per entendre l'evaporació. Aquesta tesi vol millorar el coneixement sobre l'evaporació i els mecanismes de flux de vapor, i analitzar la rellevància dels gradients de succió, de temperatura i osmòtics. Aquestes qüestions són especialment rellevants per la salinització de sòls, els mecanismes són poc coneguts malgrat el seu impacte global. Hem estudiat experiments de columna d'evaporació on s'ha trobat un procés de separació d'aigua al sòl. Per sobre del front d'evaporació, que és molt estret, el sòl conté altes concentracions a causa dels soluts transportats pel flux ascendent de líquid i la seva posterior evaporació. Per sota, les concentracions són inferiors a les inicials, perquè el vapor flueix cap avall des del front d'evaporació impulsat per gradients de temperatura. Allà condensa, causant la dilució del flux ascendent d'aigua, millorant les condicions del sòl i proporcionant una àrea on les arrels de les plantes podrien viure. Mitjançant un model de flux multifàsic no isoterm i transport reactiu dels experiments, s'han quantificat els processos per entendre la naturalesa del flux descendent de vapor. S'ha modificat la corba de retenció per representar condicions molt seques del sòl. El nostre model és compatible amb la divisió tradicional del sòl, per un front d'evaporació, en una regió seca i una regió humida. Aquest punt de vista pot ser suficient per a l'avaluació de tases d'evaporació i balanços de massa d'aigua, però no per a l'avaluació dels processos de sals, que requereixen no només el coneixement del flux d'aigua líquida, sinó també la difusió de vapor per sota del front d'evaporació. Conceptes de flux no saturat controlen el disseny de cobertures per aïllar residus sòlids. El seu objectiu és protegir els residus de la infiltració durant llargs períodes de temps mitjançant la promoció de l¿escorrentia superficial i el drenatge lateral, i evitant la biointrusió. Dos dissenys de cobertura, basats en una capa per l'evapotranspiració, una barrera de biointrusió i una barrera d'infiltració, van ser construïts. Analitzem el seu funcionament durant dos anys a través d'un complet sistema de monitorització. Es conclou que la part superior de la cobertura va funcionar com estava previst, però no així la barrera d'infiltració inferior. Es suggereixen millores de disseny: augmentar la capacitat de retenció de les capes de sorra, incloure capes de filtre i facilitar el drenatge lateral augmentant el pendent a la zona superior. S'han estudiat les variacions diàries i anuals dels fluxos de vapor a partir de dades de la cobertura i de modelació numèrica. Trobem que la major part del flux d'aigua a la part superior del sòl es produeix en la fase gasosa. Els fluxos de vapor són controlats per la temperatura i segueixen les seves fluctuacions, canviant de direcció diàriament i amb un desfasament que augmenta amb la profunditat. Els fluxos de vapor descendent són dominants durant l'estiu i els ascendents durant l'hivern. A més profunditat, els fluxos de vapor varien estacionalment, i flueixen gairebé constantment cap amunt durant les èpoques fredes, i viceversa. Les pluges tenen un efecte de refredament, revertint els fluxos de vapor a l'estiu. El flux net anual és descendent. El model demana simular flux a través de vies preferencials. Si bé els fluxos de vapor són quantitativament petits, poden representar una important font d'aigua durant l'estiu per a les arrels poc profundes. S'ha presentat també, una solució analítica per al càlcul de fluxos difusius de vapor al sòl.
La zona no saturada juega un papel importante en numerosos fenómenos ambientales. Es complejo en zonas áridas, donde los flujos de agua líquida son pequeños y los flujos de vapor adquieren relevancia. El transporte de calor, de agua y de solutos es necesario para entender la evaporación. Esta tesis quiere mejorar el conocimiento sobre la evaporación y los mecanismos de flujo de vapor, y analizar la relevancia de los gradientes de succión, temperatura y osmóticos. Estas cuestiones son especialmente relevantes para la salinización de suelos, cuyos mecanismos son poco conocidos a pesar de su impacto global. Hemos estudiado experimentos de columna de evaporación en los que se ha encontrado un proceso de separación de agua en el suelo. Por encima del frente de evaporación, que es muy estrecho, el suelo contiene altas concentraciones de sal debido a los solutos transportados por el flujo ascendente de líquido y su posterior evaporación. Por debajo, las concentraciones son inferiores a las iniciales, porque el vapor fluye hacia abajo desde el frente de evaporación impulsado por gradientes de temperatura. Allí condensa, causando la dilución del flujo ascendente de agua, mejorando las condiciones del suelo y proporcionando un área donde las raíces de las plantas podrían vivir. Mediante un modelo de flujo multifásico no isotermo y transporte reactivo de los experimentos, se han cuantificado los procesos, para entender la naturaleza del flujo descendente de vapor. Se ha modificado la curva de retención para representar condiciones muy secas del suelo. Nuestro modelo es compatible con la división tradicional del suelo, por un frente de evaporación, en una región seca y una región húmeda. Este punto de vista puede ser suficiente para la evaluación de tasas de evaporación y balances de masa de agua, pero no para la evaluación de los procesos de sales, que requieren no sólo el conocimiento del flujo de agua líquida, sino también la difusión de vapor por debajo del frente de evaporación. Conceptos de flujo no saturado controlan el diseño de coberturas para aislar residuos sólidos. Su objetivo es proteger los residuos de la infiltración durante largos periodos de tiempo mediante la promoción de la escorrentía superficial y el drenaje lateral, y evitando la biointrusión. Dos diseños de cobertura, basados en una capa para la evapotranspiración, una barrera de biointrusión y una barrera de infiltración, fueron construidos. Analizamos su funcionamiento durante dos años a través de un completo sistema de monitorización. Se concluye que la parte superior de la cobertura funcionó como estaba previsto, pero no así la barrera de infiltración inferior. Se sugieren algunas mejoras de diseño: aumentar la capacidad de retención de las capas de arena, incluir capas de filtro y facilitar el drenaje lateral aumentando la pendiente en la zona superior. Se han estudiado las variaciones diarias y anuales de los flujos de vapor a partir de datos de la cobertura y de modelación numérica. Encontramos que la mayor parte del flujo de agua en la parte superior del suelo se produce en la fase gaseosa. Los flujos de vapor son controlados por la temperatura y siguen sus fluctuaciones, cambiando de dirección diariamente y con un desfase que va en aumento con la profundidad. Los flujos de vapor descendente son dominantes durante el verano y los ascendentes durante el invierno. A mayor profundidad, los flujos de vapor varían estacionalmente, y fluyen casi constantemente hacia arriba durante las épocas frías, y viceversa. Las lluvias tienen un efecto de enfriamiento, revirtiendo los flujos de vapor en verano. El flujo neto anual es descendente. El modelo necesita simular flujo a través de vías preferenciales. Si bien los flujos de vapor son cuantitativamente pequeños, pueden representar una importante fuente de agua durante el verano para las raíces poco profundas. Se ha presentado también, una solución analítica para el cálculo de flujos difusivos de vapor en el suelo
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Tang, Chao. "Microbial diversity studies in sediments of perennially ice-covered lakes, McMurdo Dry Valleys, Antarctica." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957340921&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1269022997&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.
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Herrmann, Stefanie M., Kamel Didan, Armando Barreto-Munoz, and Michael A. Crimmins. "Divergent responses of vegetation cover in Southwestern US ecosystems to dry and wet years at different elevations." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622569.
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In the semiarid Southwestern United States, prolonged drought conditions since the early 2000s have resulted in widespread declines of the vegetation productivity in this water-constrained ecosystem, as revealed by analyses of the Normalized Difference Vegetation Index (NDVI). However, the spatial pattern of the NDVI response to dry years is not uniform: a divergent response of NDVI to precipitation is observed between the low-lying desert and the high montane forests at elevations above 2,500 meter. Weanalyzed relationships between 15 years of Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI and gridded climate data (PRISM) along elevation gradients at scales from regional to local. Our elevation-explicit analysis captures the transition from water-limited to temperature-limited ecosystems, with a sign-reversal in the correlation coefficient between precipitation and NDVI observed at about 2,500-3,000m altitude. Wesuggest warmer temperatures and less snow cover associated with drier years as explanations for high elevation gains in vegetation productivity during dry years.
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Townsend, Marjorie Louise. "Overseeding the cover crops Hairy Vetch (Vicea Villosa Roth) and Medium Red Clover (Trofolium Pratense L.) into corn (Zea Mays L.) after the last cultivation: effects on corn yield and cover crop production of dry matter and ground cover residue." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1413464088.
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Foo, Wilson L. "Comparative analysis of microbial community composition throughout three perennially ice-covered lake systems in the McMurdo Dry Valleys, Antarctica and its relationship with lake geochemistry." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957301371&SrchMode=2&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268759757&clientId=48051.
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Thesis (Ph. D.)--University of California, Riverside, 2009.Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.
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Souza, Márcia Raquel Ronconi de. "Avaliação do desempenho de diferentes tipos de cobertura seca aplicados a depósitos de rejeitos de carvão." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/96400.
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Este trabalho teve como objetivo avaliar o desempenho de diferentes tipos de coberturas secas utilizadas em células experimentais preenchidas com rejeitos piritosos de carvão mineral. Quatro células de igual dimensão foram preenchidas com rejeitos piritosos, provenientes do beneficiamento de carvão mineral da Unidade Mineira II – Verdinho, pertencente à Carbonífera Criciúma S.A., situada no município de Forquilhinha, Estado de Santa Catarina. Em relação à composição das células, a primeira foi construída sem cobertura; a segunda, com somente pré-cobertura, constituída de mistura de rejeitos; a terceira, com cobertura de argila compactada; e a quarta elaborada com sistema de barreira capilar dupla. Todas foram expostas às mesmas condições meteorológicas. Para avaliação do desempenho das coberturas analisou-se o volume e características químicas e físico-químicas da água de percolação no período compreendido entre 2009 e 2010. Os parâmetros físicoquímicos considerados foram os seguintes: pH, Eh, acidez, alcalinidade e condutividade enquanto que os parâmetros químicos foram Fe, Al, Mn, Zn e sulfato. A partir dos resultados obtidos, fez-se uma análise técnica dos diferentes tipos de cobertura seca utilizados. De acordo com análise técnica constatou-se que o melhor desempenho no tocante ao volume e à qualidade da água percolada ocorreu na célula em que se utilizou cobertura com argila compactada e na célula em que se empregou cobertura do tipo barreira capilar dupla.This work aimed to evaluate the performance of different types of dry cover employed in experimental cells filled with pyritic waste of mineral coal. Four cells with the same dimension were filled with coal tailings from the coal preparation plant of Unidade Mineira II –Verdinho, which belongs to Carbonífera Criciúma SA, located in Forquilhinha, Santa Catarina State. The first cell was constructed without any kind of cover, the second one was built with a cover composed by a mixture of coal wastes, the third one was built with a layer of compacted clay, and the forth one was constructed with a system composed by a dual-capillary barrier. All were exposed to the same meteorological conditions. To evaluate the performances of dry covers we analyzed the volume and the chemical and physicochemical characteristics of seepage between 2009 and 2010. The water was analyzed in terms of pH, Eh, acidity, alkalinity, conductivity and the concentration of Fe, Al, Mn, Zn, and sulfate. The experimental results showed that the best performance concerning the volume and the quality of the percolated water was obtained in the cell that received a cover of compacted clay and in the one that received a cover composed by dualcapillary barrier.
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Mauritsson, Karl. "Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa." Thesis, Högskolan i Skövde, Institutionen för biovetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15369.
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Natural forests are characterised by great vegetation diversity and create habitats for a major part of Earth’s terrestrial organisms. Plantation forests, which are mainly composed of a few genera of fast-growing trees, constitute an increasing fraction of global forests, but they only partly compensate for loss of area, habitat and ecological functions in natural forests. Plantation forests established near natural forests can be expected to serve as buffers, but they seem to be relatively poor in invertebrate species and it is not clear why. This bachelor’s degree project aimed at establishing the ecological and edaphic factors that correlate with soil invertebrate diversity in dry upland forests and surrounding plantation forests in eastern Africa. Some aspects of the above-ground vegetation heterogeneity were investigated since this was assumed to influence the heterogeneity of the soil environment, which is considered as critical for soil biodiversity. The obtained knowledge may be valuable in conservation activities in East African forests, which are threatened by destruction, fragmentation and exotic species. The study area was Karura Forest, a dry upland forest in Nairobi, Kenya. Three different sites were investigated; a natural forest site characterized by the indigenous tree species Brachylaena huillensis and Croton megalocarpus, and two different plantation forest sites, characterized by the exotic species Cupressus lusitanica and Eucalyptus paniculata, respectively. For each forest type, six plots were visited. Soil invertebrates were extracted from collected soil and litter samples by sieving and Berlese-Tullgren funnels. The invertebrates were identified, and the taxonomic diversity calculated at the order level. The ecological and edaphic factors, measured or calculated for each plot, were tree species diversity, ratio of exotic tree species, vertical structure of trees, vegetation cover, vegetation density, litter quality, soil pH, soil temperature and soil moisture. One-way ANOVA was used to compare soil invertebrate diversity and other variables between different forest types. Akaike’s Information Criterion and Multiple Linear Regression were used to establish linear models with variables that could explain measured variations of the diversity. There was some evidence for higher soil invertebrate diversity in natural forests than in surrounding plantation forests. The abundance of soil invertebrates was also clearly higher in natural forests, which indicates that natural forests are more important than plantation forests for conservation of soil invertebrate populations. Soil invertebrate diversity (in terms of number of orders present) was found to be influenced by forest type and litter quality. The diversity was higher at places with high amounts of coarse litter, which here is considered as more heterogenous than fine litter. The dependence on forest type was partly a consequence of differences in soil pH since Eucalyptus trees lower soil pH and thereby also soil biodiversity. No relation to heterogeneity of above-ground vegetation was found. For future conservation activities in Karura Forest Reserve it is recommended to continue removing exotic plant species and replanting indigenous trees, to prioritize the removal of Eucalyptus trees before Cypress trees, to only remove a few trees at a time and to establish ground vegetation when doing so.
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Francisco, Eros Artur Bohac. "Antecipação da adubação da soja na cultura de Eleusine coracana (L.) Gaertn., em sistema de plantio direto." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-20022003-164035/.
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O presente experimento teve por objetivo avaliar o efeito da antecipação da adubação da cultura da soja no acúmulo de matéria seca e extração de nutrientes pelo capim-pé-de-galinha (Eleusine coracana (L.) Gaertn.) e no acúmulo de matéria seca e exportação de nutrientes pela cultura da soja em sucessão, em sistema de plantio direto. O experimento foi conduzido em área experimental da Escola Superior de Agricultura "Luiz de Queiroz" (USP/ESALQ), no município de Piracicaba SP, durante o ano agrícola de 2001/2002, em solo LATOSSOLO AMARELO Distrófico. O cultivar de soja utilizado foi o BRS-133. A adubação, segundo a recomendação oficial para o estado de São Paulo, consistiu da aplicação de 90 kg de P2O5 ha -1 , 50 kg de K2O ha -1 e de micronutrientes (Co, Cu, Fe, Mn, Mo e Zn). Os tratamentos consistiram em níveis de antecipação da adubação da soja para a cultura do capim-pé-de-galinha (T1: 0%; T2: 50% de P; T3: 50% de K; T4: 100% de P; T5: 100% de K; T6: 50% de P e K; T7: 100% de P e 50% de K; T8: 50% de P e 100 % de K; T9: 100% de P e K; T10: micronutrientes; T11: 100% de P e K + micronutrientes; T12: controle), totalizando 12 tratamentos, delineados em blocos completos ao acaso com três repetições. As características avaliadas foram: produção de matéria seca, concentração e acúmulo dos nutrientes na parte aérea do capim-pé-de-galinha; acúmulo de matéria seca, concentração e acúmulo de nutrientes nos grãos de soja. As principais conclusões são: a) no que concerne à produtividade de matéria seca, o capim Eleusine coracana (L.) Gaertn. constitui-se em espécie recomendável à produção de palhada em sistema de produção sob plantio direto, desde que implantada em solo com média a alta fertilidade; b) considerando-se o acúmulo de nutrientes na matéria seca produzida, constata-se que o capim Eleusine coracana (L.) Gaertn. apresenta a seguinte seqüência de absorção: K > N > Ca > Mg > S > P >> Mn> Fe > Zn > Cu; c) a produção de matéria seca e o acúmulo dos nutrientes fósforo e cálcio pelo capim Eleusine coracana (L.) Gaertn. aumentam com a aplicação antecipada da adubação fosfatada de base recomendada para a soja; d) a antecipação da adubação de base da soja, por ocasião da instalação do capim Eleusine coracana (L.) Gaertn., não diminui o acúmulo de matéria seca e nem interfere com a exportação de nutrientes pelas plantas de soja.This research was to evaluate the effect of the anticipation of soybean fertilization on dry matter production and extraction of nutrients by finger millet (Eleusine coracana (L.) Gaertn.) and on dry matter accumulation and exportation of nutrients by soybean seed cultivated in sequence, in a no-till system. The experiment was carried out at the experimental fields of Escola Superior de Agricultura "Luiz de Queiroz" (USP/ESALQ), in Piracicaba-SP, during the growing season of 2001/2002, in an Oxisol. The cultivar used was BRS-133. The soybean fertilization, according to the official recommendation to the state of São Paulo, consisted in the application of 90 kg of P2O5 ha -1, 50 kg of K2O ha -1 and of micronutrients (Co, Cu, Fe, Mn, Mo and Zn). The treatments consisted of levels of anticipation of the soybean fertilization to the finger millet crop (T1: 0%; T2: 50% of P; T3: 50% of K; T4: 100% of P; T5: 100% of K; T6: 50% of P and K; T7: 100% of P and 50% of K; T8: 50% of P and 100 % of K; T9: 100% of P and K; T10: micronutrients; T11: 100% of P and K + micronutrients; T12: controle), totaling 12 treatments, designing a complete randomized blocks with three replications. The evaluated characteristics were: dry matter production, concentration and nutrients accumulation at biomass of finger millet; dry matter accumulation, nutrients concentration and accumulation in soybean seed. The main conclusions are: a) in reference to the dry matter production, Eleusine coracana (L.) Gaertn. is a recommended specie to obtain plant residues in no-till systems, since it is growing on medium to high fertility soils; b) considering the nutrients accumulation in dry matter, it is verified that Eleusine coracana (L.) Gaertn. presents the following sequence of nutrient absorption: K > N > Ca > Mg > S > P >> Mn > Fe > Zn > Cu; c) the anticipation of the soybean fertilization to the Eleusine coracana (L.) Gaertn. sowing do not decrease dry matter accumulation nether interferes with the nutrients exportation by soybean seed; d) dry matter production and phosphorus and calcium accumulation by Eleusine coracana (L.) Gaertn. increase in response of phosphorus anticipation from soybean fertilization.
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Manetsa, Viviane. "Etude multi-échelles des précipitations et du couvert végétal au Cameroun : analyses spatiales, tendances temporelles, facteurs climatiques et anthropiques de variabilité du NDVI." Thesis, Dijon, 2011. http://www.theses.fr/2011DIJOS075/document.
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De par sa géométrie et sa situation géographique (2°N-13°N – 8°E-16°E ; ouverture sur l’océan Atlantique), le Cameroun offre l’avantage de proposer un ensemble représentatif des climats régionaux rencontrés en Afrique tropicale. La diminution des cumuls de précipitations enregistrée dans la région pendant la seconde moitié du XXe siècle, est associée à la récurrence de périodes anormalement sèches, essentiellement au cœur de la saison des pluies. Ces conditions ont amplifié la dégradation du couvert végétal au travers ses contraintes socioéconomiques et démographiques (déforestation, extension des surfaces d’activité). Les conséquences souvent dommageables de la variabilité climatique en général, et des sécheresses en particulier, sur les hommes et leurs activités suscitent l’intérêt de développer des études pour mieux comprendre comment le climat et les pressions naturelles et environnementales interagissent localement. Ainsi, l’objectif de cette thèse est de diagnostiquer la variabilité multiéchelle (saisonnière, interannuelle, intra-saisonnière, synoptique) des précipitations et les relations qu’elle entretient avec le couvert végétal au sens large qui, à ces latitudes, est associé directement ou non, à la dynamique d’occupation et d’utilisation du sol, particulièrement sur la période 1951-2002. A partir de données de précipitations observées (CRU/ponctuelles), les modes spatiaux de la variabilité ont été définis aux échelles annuelles et interannuelles, par Analyses en Composante Principale (ACP) et la Classification Ascendante Hiérarchique (CAH). Ces méthodes de classifications ont permis de discriminer cinq zones climatiques, différentes les unes des autres par l’intensité des cumuls et la saisonnalité (unimodal/bimodal). Pour chaque zone, l’attention a été portée sur les paramètres intrasaisonniers qui modulent la variabilité annuelle telle que, les séquences sèches (nombre, longueur, périodes d’occurrence) et les variations des dates de début et de fin des périodes végétatives. La répartition du couvert végétal dans l’espace et dans le temps (1982-2002) a été étudiée, en utilisant des méthodes de classification non supervisée (ISODATA) sur les données de NDVI (Normalized Difference Vegetation index) à 8km de résolution. Enfin, des méthodes statistiques et de télédétection ont permis d’évaluer l’impact des facteurs pluviométriques et anthropogéniques (croissance démographique et utilisation du sol) sur la dynamique du couvert végétal en utilisant des bases de données à plus fine résolution (NDVI/1Km ; Global Land Cover (GLC 2000/1Km)). Ces dernières investigations ont été menées dans le Nord-Cameroun (6°N-13°N – 11°E-16°E), qui est la région la plus sensible des points de vue climatique, économique et environnementalDue to its shape and location (2°N-13°N – 8°E-16°E; proximity of the Atlantic Ocean), Cameroon is characterized by a panel of cross-regional climate encountered widely in tropical Africa. Over the region, the decrease rainfall during the second half of the last century has been shown to be associated with stronger recurrence of drier periods, specifically in the core of the rainy season. These conditions have favored the degradation of vegetation cover, driven by socioeconomic and demographic constraints. The substantial impacts on human activities and local society highlight the need to better understand how climate and environmental dynamics do interact locally. The aim of this study is to diagnose multi-scale rainfall variability and its relationship with vegetation cover (natural and/or grown), which is directly or indirectly associated to the land-cover and land-use dynamics at these latitudes. Using observed rainfall data (Climatic Research Unit/punctual), the spatial modes of rainfall variability at annual and intraseasonal scales are defined through Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC). These regionalizations lead to the discretisation of 5 climatic zones, distinguished from each other, by both the amount of rainfall and seasonality (unimodal / bimodal). New intraseasonal dry spells statistics (number, length, period of occurrence) are produced as well as dates of onset and end of the vegetative seasons by sub-regions. Using unsupervised classification methods (such as ISODATA) in Normalized Difference Vegetation Index (NDVI) data at a 8km spatial resolution, vegetation cover spatiotemporal distribution and typology were produced. Then, based on a concomitant use of statistical and GIS approaches, higher resolutions of NDVI (SPOT-1Km) and Global Land-cover data (GLC 2000), allowed to further evaluate both the pluviometric and anthropogenic factors (demography, land use) influencing vegetation dynamics. Analysis were carried out in Northern Cameroon (6°N-13°N – 11°E-16°E), which is the most sensitive region with regards to climatic and environmental variability, that could lead to important socio-economic thread locally
Books on the topic "Dry covers"
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Limited, Senes Consultants. Evaluation of alternate dry covers for the inhibition of acid mine drainage from tailings: Final report. Ottawa, Ont: Canada Centre for Mineral and Energy Technology = Centre canadien de la technologie des minéraux et de l'énergie, 1994.
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Yanful, Ernest K. Development of laboratory methodologies for evaluating the effectiveness of reactive tailings covers: Final report. Ottawa, Ont: Canada Centre for Mineral and Energy Technology = Centre canadien de la technologie des minéraux et de l'énergie, 1991.
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G, Bradbury A., ed. Collecting British first day covers. 6th ed. Leicester: A.G. Bradbury, 1987.
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Severe, Martin L. The comprehensive listing of artcraft covers, 1939-1992. 3rd ed. Sidney, Ohio: Amos Press, 1993.
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Severe, Martin L. The comprehensive listing of artcraft covers, 1939-1991. 2nd ed. Sidney, Ohio: Amos Philatelics, Inc., dba Scott Pub. Co., 1992.
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G, Bradbury A., ed. Collecting British First Day Covers. Leicester: A. G.Bradbury, 2002.
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Porter, N. C. Collecting British first day covers. Stoneygate: A. G. Bradbury, 1995.
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G, Bradbury A., ed. Collecting British first day covers: A complete guide for all issues of Great Britain first day covers. Stoneygate: A. G. Bradbury, 1998.
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Porter, N. C. Collecting British first day covers: A complete guide for all issues of Great Britain first day covers. Leicester): A. G. Bradbury (3 Link Road, Stoneygate, Leicester LE2 3RA, 1996.
Find full textBook chapters on the topic "Dry covers"
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Fritsen, Christian H., Edward E. Adams, Christopher P. Mckay, and John C. Priscu. "Permanent Ice Covers of the Mcmurdo Dry Valleys Lakes, Antarctica: Liquid Water Contents." In Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica, 269–80. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/ar072p0269.
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Adams, Edward E., John C. Priscu, Christian H. Fritsen, Scott R. Smith, and Steven L. Brackman. "Permanent Ice Covers of the Mcmurdo Dry Valley Lakes, Antarctica: Bubble Formation and Metamorphism." In Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica, 281–95. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/ar072p0281.
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Kistinger, Stephan, Guido Deissmann, Martin Goldsworthy, and Ralf H. Stollenwerk. "Evaluation of the long-term durability of engineered dry covers for mining wastes, and consideration of associated design constraints." In Uranium in the Aquatic Environment, 155–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-55668-5_18.
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Gunin, Peter D., Elizabeth A. Vostokova, Nadezhda I. Dorofeyuk, Pavel E. Tarasov, and Clanton C. Black. "Assessing Present-Day Plant Cover Dynamics." In Vegetation Dynamics of Mongolia, 79–129. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-015-9143-0_4.
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Jadallah, Elzahraa. "Water reporting beyond dry pieces, nurture your coverage." In Water conflicts and cooperation: a media handbook, 23–27. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247954.0006.
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Abstract This chapter provides practical tips and tricks for water reporting. Water investigative work can be a rich field, where journalists can cover in-depth issues such as pollution, water projects, dams, water conflicts, among others. In-depth reporting gains its charm from its ability to reflectvarious sides of the story, reveal what is hidden, and possibly incur real change on the ground.
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Mate, C. Mathew, and Robert W. Carpick. "Surface Forces Derived from Surface Energies." In Tribology on the Small Scale, 140–80. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780199609802.003.0006.
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As it more practical to measure the forces acting between two contacting surfaces then the energies of surfaces, this chapter covers those surface forces that are derived from surface energies. The starting point is Derjaguin’s approximation, which relates the energy between two flat surfaces to the force in other geometries: sphere/flat, sphere/sphere, and crossed cylinders. Next is a discussion of the surface forces in dry contacts with no liquid menisci around the contact points. This discussion covers the cases where adhesion causes significant deformation (JKR theory), where deformation is insignificant (DMT theory), and the cases in between. How surface roughness impacts adhesion is also discussed. The second half of this chapter deals with how liquid menisci around contacts contribute to adhesion forces, both for the sphere-on-flat geometry and for contacting rough surfaces.
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Alfredo Rodríguez-Pineda, José, and Lorrain Giddings. "Agricultural Drought in North-Central Mexico." In Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0018.
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Drought is the most significant natural phenomenon that affects the agriculture of northern Mexico. The more drought-prone areas in Mexico fall in the northern half of the country, in the states of Chihuahua, Coahuila, Durango, Zacatecas, and Aguascalientes (figure 10.1). The north-central states form part of the Altiplanicie Mexicana and account for 30.7% of the national territory of 1,959,248 km2. This area is characterized by dry and semidry climates (Garcia, 1981) and recurrent drought periods. The climate of Mexico varies from very dry to subhumid. Very dry climate covers 21%, dry climate covers 28%, and temperate subhumid and hot subhumid climates prevail in 21% and 23% of the national territory, respectively. About 20 years ago, almost 75% of Mexico’s agricultural land was rainfed, and only 25% irrigated (Toledo et al., 1985), making the ratio of rainfed to irrigated area equal to 3. However, for the northern states this ratio was 3.5 during the 1990–98 period (table 10.1). Because of higher percentage of rain-fed agriculture, drought is a common phenomenon in this region, which has turned thousands of hectares of land into desert. Though the government has built dams, reservoirs, and other irrigation systems to alleviate drought effects, rain-fed agriculture (or dryland farming) remains the major form of cultivation in Mexico. In Mexico, there is no standard definition for agricultural drought. However, the Comisión Nacional del Agua (CNA; i.e., National Water Commission), which is a federal agency responsible for making water policies, has coined its own definition for drought. This agency determines whether a particular region has been affected by drought, by studying rainfall records collected from the national climatic network. The national climatic network is spread throughout the country and is managed by the Servicio Meteorológico Nacional (SMN; i.e., National Meteorological Services). The CNA determines, for a municipal region, if the rainfall is equal to or less than one standard deviation from the long-term mean over a time period of two or more consecutive months. If it is, then the secretary of state declares drought for the region.
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"Ophthalmology." In Oxford Handbook for Medical School, edited by Kapil Sugand, Miriam Berry, Imran Yusuf, Aisha Janjua, Chris Bird, David Metcalfe, Harveer Dev, et al., 499–520. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780199681907.003.0025.
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Chapter 25 presents an illustrated overview of clinical ophthalmology for the medical student. Eye casualty is an excellent setting to learn about the assessment and management of acute presentations in ophthalmology. The most important acute presentations in ophthalmology are summarized including the most common causes of red eye (acute angle closure glaucoma, bacterial keratitis, anterior uveitis, scleritis, endophthalmitis, conjunctivitis, dry eye), and visual loss (retinal vascular disease, anterior ischaemic optic neuropathy, vitreous haemorrhage, macular haemorrhage, retinal detachment, stroke, transient ischaemic attacks, migraine). The most frequently encountered chronic diseases in ophthalmology are cataract, glaucoma, diabetic retinopathy, and age-related macular degeneration. This chapter covers the risk factors, clinical assessment, investigation, and management (medical, laser, and surgical) of these disorders. Ophthalmic microsurgery is fascinating to observe, and this chapter provides some orientation to medical students attending eye theatres including an overview/images of phacoemulsification cataract surgery, trabeculectomy, and vitrectomy surgery.
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Lawrence, Deborah, and David R. Foster. "Recovery of Nutrient Cycling and Ecosystem Properties Following Swidden Cultivation: Regional and Stand-Level Constraints." In Integrated Land-Change Science and Tropical Deforestation in the Southern Yucatan. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780199245307.003.0014.
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The total area of agricultural systems in tropical Mexico increased by 64 per cent from 1977 to 1992—a mean annual deforestation rate of 1.9 per cent (Cairns et al. 2000). In all likelihood, this rate has continued for the past ten years. Dry tropical forest covers 8 per cent of Mexico and is subject to conversion for agricultural use (Trejo and Dirzo 2000). Because the southern Yucatán contains the largest contiguous block of dry tropical forest in Mexico and Central America, understanding the biogeochemical consequences of land-use change there is important for effective national and international conservation and development efforts. Over the past four decades the southern Yucatán peninsular region has undergone an increasing amount and intensity of land use (Chs. 3, 9, 10). These land uses, many focused on swidden practices, alter the structure and function of forested lands and often generate new feedbacks in terms of subsequent human use. Consequently, a major goal in assessing regional environmental change is to understand how biogeochemical processes respond to land-use change, emphasizing the potential of a human-dominated landscape to sustain continued human use. One of the greatest challenges in these studies is to untangle the effects of environmentally induced variation from, for example, climate, geology, or natural disturbance, from that induced by human activity. In the SYPR project the approach to this challenge has been to investigate variation in ecosystem processes in several study sites across the dominant environmental gradients while focusing on the influence of local, human-controlled factors within a given area. In the southern Yucatán peninsular region annual precipitation increases by more than 50 per cent over a distance of 120km. Median annual precipitation varies from about 900mm in the northern part of the study area to about 1,400mm in the southern part. This dramatic gradient overlies a seasonal pattern shared by all sites regardless of their total annual precipitation. Rainfall is highly variable, with a pronounced dry period lasting from four to six months, depending on latitude. The range in precipitation observed in the study area encompasses approximately 50 per cent of the variation in precipitation of dry tropical forests worldwide (Murphy and Lugo 1986).
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"Appendix:." In Cover Name: Dr. Rantzau, 222–23. The University Press of Kentucky, 2019. http://dx.doi.org/10.2307/j.ctvdtpj8s.34.
Full textConference papers on the topic "Dry covers"
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Williams, David. "Improving performance of soil covers over waste rock dump tops in dry climates." In Eighth International Seminar on Mine Closure. Australian Centre for Geomechanics, Cornwall, 2013. http://dx.doi.org/10.36487/acg_rep/1352_22_williams.
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Wang, Xin, and Patrick Kwon. "Dry Turning of Commercially Pure Aluminium With Carbide Tools." In ASME 2010 International Manufacturing Science and Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/msec2010-34064.
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Dry turning test was performed on commercial pure aluminum Al1100 with two grades of carbide (WC-Co) tool, fine and coarse grained grades. Because of the tiny amount of abrasives in Al1100, the resulting tool wear is mainly sliding wear on flank surface. In our experiment, the fine grain carbide tool has more wear than coarse grain carbide tool despite of the miniscule wear on both carbide grades tools. Notably, the microfracture was only observed on the fine grain carbide tool’s nose due to the low fracture resistance of fine grain carbide. Using Confocal Laser Scanning Microscopy (CLSM) and wavelet filtering, the built up edge (BUE) and tool wear evolutions were analyzed. The volume of BUE becomes the maximum at the beginning of the machining and diminishes as the cobalt was worn down from the tool surface, eventually reaching a relatively steady state after half hour’s turning. The fine grain carbide tool have more built up edge than coarse grain carbide tool because of the higher cobalt content with the fine grain carbide. Oxygen from the air may play a very important role in the adhesion between aluminum and carbide tool. Two types of built up edge was found in the experiment. The first type BUE is huge and covers whole tool surface, which is mainly aluminum. The second type BUE is very thin (∼1–2microns), which covers relatively small area of tool surface. This location is characterized by both high temperature and the presence of the oxygen from the air trapped between tool and work material. This second type of BUE has much better resistance to the NaOH solution, which is metal oxide (Aluminum oxide or complex oxide such as spinel), and it could increase the adhesion between tool and work material. Mainly, in dry turning commercial pure aluminum, the larger carbide grain size has a better wear performance.
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H.M. Keener, J.A. Pecchia, G.L. Reid, F.C. Michel, and D.L. Elwell. "Effects of Aeration and Covers on NH3, Water and Dry Matter Loss During Windrow Composting of Dairy Manure." In 2002 Chicago, IL July 28-31, 2002. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2002. http://dx.doi.org/10.13031/2013.9385.
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Carstensen, Conrad, and Roald Skorping. "Experience With DLE Turbines at Offshore Installations." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0657.
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In this paper experience with some of the first gas turbines equipped with dry low NOx combustors installed in the North Sea is presented. The case history covers LM2500 and LM6000 gas turbines. The paper outlines further some of the technical challenges for future applications in conformance with recent revisions of power plant air emission guidelines.
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Liu, Xiang, Yue Li, Jinhua Wang, and Bin Wu. "Stress Concentration Factor Calculation for the Hooks in Lifting Appliance of Spent Fuel Well Cover." In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30272.
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The spent nuclear fuel of HTR-PM (High Temperature Reactor–Pebblebed Modules) will be dry stored in wells. In the mouth of each well, there is a cover weighing 11 tons. A lifting appliance with three hooks is used to open and close the covers. The hooks are L-shaped with fillet at the inside corner. The stress concentration at the corner has a significant impact on the strength and fatigue life of hooks. For optimizing the structure of the hook, the stress concentration factor related to the radius of fillet is calculated by both theoretical and numerical methods. The theoretical calculation is based on the Saint-Venant’s Principle and the analytical solution of a curved beam. The result is consistent with the numerical calculation performed by the finite element method.
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Zhang, Shengbiao, Zhandong Wang, Yan Yan, Guifang Sun, and Zhonghua Ni. "Numerical Simulation and Innovative Structure of Drainage Cover." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77197.
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A fluid simulation was conducted on the flow states of water and drainage gas from the drainage cover in underwater local dry laser welding. The results of the simulation of gas volume fraction are obtained. Drainage cover was developed based on the drainage cover model. Experiments of drainage in this machined drainage cover was carried out, and were compared with the numerical simulation. The results show high similarity, which verifies the feasibility. Then, innovative structure featuring an uneven buffer around the exit of drainage cover are proposed to improve the performance of drainage. A group of 3D models of fluid domain related to differently characterized drainage covers was designed and the flow states were simulated. They are N-model with a narrow outlet, S-model with a smooth buffer added additionally based on N-model, U-model with an uneven buffer compared with S-model, and W-model with a wide outlet and the diameter of outlet twice than N-model. The gas volume fracture distributions were recorded and in comparison with each other. The results indicate that U-model with the uneven buffer realized the deepest drainage depth.
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Yu, John J. "On Occurrence of Reverse Full Annular Rub." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45153.
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This paper discusses reverse full annular rub based on a two degree-of-freedom rotor/seal model where a rubbing location can be simulated away from the lumped rotor mass. The analytical model is much closer to the experimental setup for comparison of results, and real machines for analysis, than the previous one degree-of-freedom model. Its closed-form solution is given including reverse rub amplitudes and relative phases as well as the normal contact force. The exact frequency equation in polynomial form yields reverse full annular rub frequencies without having to neglect any parameters. Many conclusions can be drawn directly from explicit expressions without numerical calculations. The solution with non-positive normal contact force indicates a dry-friction whirl/whip-free region, usually accompanied by low friction and/or high damping. The analytical study covers both dry-friction whirl and dry-friction whip, and their relations with dry friction factor, damping, and rotor speed. Range of reverse rub frequencies, their relation with rotor and rotor/seal coupled natural frequencies, and direction of frictional force, are also revealed. Destructive dry-friction whip experimental results are given which have fully confirmed the analytical formulas.
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Gambaryan-Roisman, Tatiana, and Peter Stephan. "Falling Films in Micro- and Minigrooves: Heat Transfer and Flow Stability." In ASME 2003 1st International Conference on Microchannels and Minichannels. ASMEDC, 2003. http://dx.doi.org/10.1115/icmm2003-1054.
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Structured (in particular, micro- and minigrooved) wall surfaces may improve numerous industrial processes, including falling film evaporation, thin film evaporation in lean premixed prevaporized combustion technology (LPP), and spray and jet cooling. The advantages of such surfaces include the promotion of ultra-thin film evaporation at the apparent contact lines and the prevention of dry patches on hot surfaces. However, the behavior of thin film flow on structured surfaces has not yet been comprehensively studied. We derive a model describing the heat transfer in liquid film flowing down inclined micro- or minigrooved walls. The derived model accounts for peculiarities of the evaporation process in the vicinity of the liquid-vapor-solid contact line (“micro region”) and their effect on the overall heat transfer rate. It is shown that the effect of the micro region is to increase the overall heat transfer rate at the constant fluid flow rate. A long-wave stability analysis has been performed to quantify the effect of the capillary structure on the film stability properties. Sinusoidal and triangular longitudinal groove shapes have been considered. Two cases have been studied: (i) the film completely covers the wall structure; (ii) the film partly covers the wall structure. It is shown that the longitudinal grooves completely covered by the liquid have a stabilizing effect on the falling film flow. The performed analysis is a step towards modeling the wavy motion of the liquid film on grooved surfaces.
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Suratkar, A. S., A. Y. Sajjadi, and K. Mitra. "Non-Destructive Detection of Defects in Composite Boat Hulls." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65187.
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This paper demonstrates use of thermal imaging for nondestructive defect detection in a composite boat hull which covers a large area. There is a strong demand in the boat industry for a non-destructive method that can detect defects such as delamination, voids of air or fluid, cracks, acid, dry mat, and carbon fiber. These defects are always difficult to detect as they occur inside the walls of the boat. Currently, ultrasound and manual inspection methods are used to identify these defects. The manual checking technique is unscientific; furthermore the ultrasound method is not acceptable due to unsatisfactory results. Thermal imaging involves detecting infra-red radiation from a hot body; this is captured by a thermal imaging camera. A thermal heat gun is used to heat the walls of the boat hull. After heating for a specific time period, the walls of the boat start emitting radiation. Dry void attains the highest peak intensity value for short time heating followed by Acid. Other defects like carbon fiber, delamination, and dry mat took longer time to attain higher intensity value. The decay of radiations is also different for various types of defects. The maximum intensity decay occurs for dry void as compared to other defects. From the results obtained so far, it can be inferred that thermal imaging can distinctly differentiate the different kinds of defects, as well as the unaffected areas of the boat wall.
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Huitenga, Holger, and Eric R. Norster. "Development Approach to the Dry Low Emission Combustion System of MAN Diesel and Turbo Gas Turbines." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25164.
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The THM series of industrial gas turbines covers a power range of 6 to 12.5 MW and has been improved and uprated over many years. The majority of turbines installed are still in commercial operation and they are mainly used for compressor drives but also find generator applications. In recent years the constraints of emission legislations for new and existing gas turbines has made a development programme for a dry low emission (DLE) combustion system essential. The combustion system apart from meeting latest emission targets of 75 mg/mN3 NOx and 100 mg/mN3 CO must be suitable for both, new and retrofit engine options and therefore compact for standard enclosure installation. In addition the design should be simple and robust with the same accessibility as the existing standard combustion system. The paper describes the design and development steps to provide a prototype lean premixed DLE combustion system. The basic approach for a simple lean premixed design together with aero-thermodynamic sizing for pressure loss, flow proportions, stability and cooling is described. The initial efforts were directed to a system for the 11 MW THM 1304-11AP machine, with combustor atmospheric testing to verify design parameters and operating limits. The development was continued by subsequent high pressure testing of the prototype, starting with suitable units in the MAN engine test facility, omitting any high pressure rig tests. Field tests were carried out on a compressor drive application on a gas pumping station to prove long term durability. Adaptations of the design are now engine-tested for other THM models, even recuperated ones. Also, the combustor technology and methods developed here provide the basis for the combustors on the new MAN MGT 6100 and 6200 engines [1].
Reports on the topic "Dry covers"
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Stormont, J. C., M. D. Ankeny, M. E. Burkhard, M. K. Tansey, and J. A. Kelsey. Assessment of an active dry barrier for a landfill cover system. Office of Scientific and Technical Information (OSTI), March 1994. http://dx.doi.org/10.2172/10138200.
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Pearce, Lauren. Covert Malware Launching and Data Encoding: Malware Analysis Day 5. Office of Scientific and Technical Information (OSTI), June 2018. http://dx.doi.org/10.2172/1457292.
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Austin, Meg. Improving 30-Day Foreacsts of Great Lake Ice Cover: Phase III 30-Day Spatial Forecasts. Fort Belvoir, VA: Defense Technical Information Center, February 2006. http://dx.doi.org/10.21236/ada444213.
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Knoll, R. W., and E. R. Gilbert. Evaluation of cover gas impurities and their effects on the dry storage of LWR (light-water reactor) spent fuel. Office of Scientific and Technical Information (OSTI), November 1987. http://dx.doi.org/10.2172/5599035.
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Kistner, Erica. A Field Day to the Long Term Agricultural Research Site. USDA Midwest Climate Hub, October 2016. http://dx.doi.org/10.32747/2016.6957454.ch.
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Soil erosion is quickly becoming a severe problem throughout the Midwest and the situation is predicted to worsen unless more sustainable management practices are adopted. Management practices like reduced tillage and cover crops are recommended to help present soil erosion, enhance soil quality, and reduce greenhouse gas emissions.
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Kistner, Erica. A Field Day to the Long Term Agricultural Research Site, Hamilton County, IA. Ames, Iowa: United States Department of Agriculture, Midwest Climate Hub, February 2018. http://dx.doi.org/10.32747/2018.6592637.ch.
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Soil erosion is quickly becoming a severe problem throughout the Midwest and the situation is predicted to worsen unless more sustainable management practices are adopted. Management practices like reduced tillage and cover crops are recommended to help present soil erosion, enhance soil quality, and reduce greenhouse gas emissions.
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Kelly, Luke. Humanitarian Evidence Summary No.14. Institute of Development Studies (IDS), May 2021. http://dx.doi.org/10.19088/k4d.2021.069.
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This is the 14th monthly Humanitarian Evidence Summary (HUMES) to signpost FCDO and other UK government departments to the latest relevant evidence and discourse on humanitarian action to inform and support their response. It is the result of 1 day of work per month and is not intended to be a comprehensive summary of available evidence on humanitarian action but aims to make original documents easily accessible to decision-makers that, if relevant to them, they could refer to before making decisions. This summary covers publications on Enhancing protection and humanitarian access; Needs assessment and analysis; Accountability to affected populations; Cash programming; Managing risk better, preparedness and anticipation; Resilience and protracted crisis; Other and Resource Hubs.
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Kelly, Luke. Humanitarian Evidence Summary No.12. Institute of Development Studies (IDS), March 2021. http://dx.doi.org/10.19088/k4d.2021.031.
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This is the 12th monthly Humanitarian Evidence Summary (HUMES) to signpost FCDO and other UK government departments to the latest relevant evidence and discourse on humanitarian action to inform and support their response. It is the result of 1 day of work per month and is not intended to be a comprehensive summary of available evidence on humanitarian action but aims to make original documents easily accessible to decision-makers that, if relevant to them, they could refer to before making decisions. This summary covers publications on Enhancing protection and humanitarian access; Needs assessment and analysis; Accountability to affected populations; Cash programming; Managing risk better, preparedness and anticipation; Other; and Resource Hubs.
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Kelly, Luke. Humanitarian Evidence Summary No.15. Institute of Development Studies (IDS), June 2021. http://dx.doi.org/10.19088/k4d.2021.089.
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This is the 15th monthly Humanitarian Evidence Summary (HUMES) to signpost FCDO and other UK government departments to the latest relevant evidence and discourse on humanitarian action to inform and support their response. It is the result of 1 day of work per month and is not intended to be a comprehensive summary of available evidence on humanitarian action but aims to make original documents easily accessible to decision-makers that, if relevant to them, they could refer to before making decisions. This summary covers publications on Enhancing protection and humanitarian access; Needs assessment and analysis; Accountability to affected populations; Cash programming; Managing risk better, preparedness and anticipation; Resilience and protracted crisis; Other; and Resource Hubs.
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Ripey, Mariya. NUMBERS IN THE NEWS TEXT (BASED ON MATERIAL OF ONE ISSUE OF NATIONWIDE NEWSPAPER “DAY”). Ivan Franko National University of Lviv, March 2021. http://dx.doi.org/10.30970/vjo.2021.50.11106.
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The article is devoted to the analysis of the digital content of publications of one issue of the daily All-Ukrainian newspaper “Den” (March 13-14, 2020). The author aims to identify the main thematic groups of digital designations, as well as to consider cases of justified and unsuccessful use of digital designations. Applying the content analysis method, the author identifies publications that contain numerical notations, determines the number of such notations and their affiliation with the main subject groups. Finds that the thematic group of digital designations “time” (58.6% of all digital designations) is much more dominant. This indicates that timing is the most important task of a newspaper text. The second largest group of digital designations is “measure” (15.8% of all digital designations). It covers dimensions and proportions, measurements of distance, weight, volume, and more. The third largest group of digital signage is money (8.2% of all digital signage), the fourth is numbering (5.2% of all digital signage), and the fifth is people (4.4% of all digital signage). The author focuses on the fact that the digits of the journalist’s text are both a source of information and a catch for the reader. Vivid indicators give the text a sense of accuracy. When referring digital data to the text, journalists must adhere to certain rules for the writing of ordinal numbers with incremental graduation; submission of dates; pointing to unique integers that are combined (or not combined) with units of physical quantities, monetary units, etc.; writing a numerator at the beginning of a sentence; unified presentation of data. This will greatly facilitate the reader’s perception of the information.