993 resultados para Growing medium


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As an extension vegetable specialist with a strong interest in organic farming and in assisting farmers to make a living, I relished this book. Leslie Duram is a geographer at Southern Illinois University Carbondale who has her roots in Kansas and is motivated by a love for Plains agriculture. The book, which she describes as a piece of advocacy scholarship, is at once scholarly, informative, and entertaining. In six well-organized chapters Duram provides an overview of organic farming within the context of overall U.S. agriculture and society (with our growing demand for organic food), reviews research describing organic farms and farmers , presents and analyzes the stories of five successful organic family farms, and offers a vision of a future American agriculture based on medium-sized organic family farms.

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Maximal amounts of prodigiosin were synthesized in either minimal or complete medium after incubation of cultures at 27 C for 7 days. Biosynthesis of prodigiosin began earlier and the range of temperature for formation was greater in complete medium. No prodigiosin was formed in either medium when cultures were incubated at 38 C; however, after a shift to 27 C, pigmentation ensued, provided the period of incubation at 38 C was not longer than 36 hr for minimal medium or 48 hr for complete medium. Washed, nonpigmented cells grown in either medium at 38 C for 72 hr could synthesize prodigiosin when suspended in saline at 27 C when casein hydrolysate was added. These suspensions produced less prodigiosin at a slower rate than did cultures growing in casein hydrolysate at 27 C without prior incubation at 38 C. Optimal concentration of casein hydrolysate for pigment formation by suspensions was 0.4%; optimal temperature was 27 C. Anaerobic incubation, shift back to 38 C, killing cells by heating, or chloramphenicol (25 mug/ml) inhibited pigmentation. Suspensions of washed cells forming pigment reached pH 8.0 to 8.3 rapidly and maintained this pH throughout incubation for 7 days. Measurements of viable count and of protein, plus other data, indicated that cellular multiplication did not occur in suspensions of washed cells during pigment formation. By this procedure utilizing a shift down in temperature, biosynthesis of prodigiosin by washed cells could be separated from multiplication of bacteria.

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Funded by BBSRC. Grant Number: LK0863 Natural Environment Research Council (NERC) Carbo-BioCrop project. Grant Number: NE/H01067X/1 MAGLUE project

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We investigated the molecular and physiological processes of sugar uptake and metabolism during pollen tube growth and plant fertilization. In vitro germination assays showed that petunia (Petunia hybrida) pollen can germinate and grow not only in medium containing sucrose (Suc) as a carbon source, but also in medium containing the monosaccharides glucose (Glc) or fructose (Fru). Furthermore, high-performance liquid chromatography analysis demonstrated a rapid and complete conversion of Suc into equimolar amounts of Glc and Fru when pollen was cultured in a medium containing 2% Suc. This indicates the presence of wall-bound invertase activity and uptake of sugars in the form of monosaccharides by the growing pollen tube. A cDNA designated pmt1 (petunia monosaccharide transporter 1), which is highly homologous to plant monosaccharide transporters, was isolated from petunia. Pmt1 belongs to a small gene family and is expressed specifically in the male gametophyte, but not in any other vegetative or floral tissues. Pmt1 is activated after the first pollen mitosis, and high levels of mRNA accumulate in mature and germinating pollen. A model describing the transport of sugars to the style, the conversion of Suc into Glc and Fru, and the active uptake by a monosaccharide transporter into the pollen tube is presented.

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Suspension-cultured Chenopodium album L. cells are capable of continuous, long-term growth on a boron-deficient medium. Compared with cultures grown with boron, these cultures contained more enlarged and detached cells, had increased turbidity due to the rupture of a small number of cells, and contained cells with an increased cell wall pore size. These characteristics were reversed by the addition of boric acid (≥7 μm) to the boron-deficient cells. C. album cells grown in the presence of 100 μm boric acid entered the stationary phase when they were not subcultured, and remained viable for at least 3 weeks. The transition from the growth phase to the stationary phase was accompanied by a decrease in the wall pore size. Cells grown without boric acid or with 7 μm boric acid were not able to reduce their wall pore size at the transition to the stationary phase. These cells could not be kept viable in the stationary phase, because they continued to expand and died as a result of wall rupture. The addition of 100 μm boric acid prevented wall rupture and the wall pore size was reduced to normal values. We conclude that boron is required to maintain the normal pore structure of the wall matrix and to mechanically stabilize the wall at growth termination.

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Different non-Fourier models of heat conduction have been considered in recent years, in a growing area of applications, to model microscale and ultrafast, transient, nonequilibrium responses in heat and mass transfer. In this work, using Fourier transforms, we obtain exact solutions for different lagging models of heat conduction in a semi-infinite domain, which allow the construction of analytic-numerical solutions with prescribed accuracy. Examples of numerical computations, comparing the properties of the models considered, are presented.

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Despite the considerable potential of advanced manufacturing technologies (AMT) for improving the economic performance of many firms, a growing body of literature highlights many instances where realising this potential has proven to be a more difficult task than initially envisaged. Focussing upon the implementation of new manufacturing technologies in several smaller to medium sized enterprises (SME), the research examines the proposition that many of these problems can be attributed in part to inadequate consideration of the integrated nature of such technologies, where the effects of their implementation are not localised, but are felt throughout a business. The criteria for the economic evaluation of such technologies are seen as needing to reflect this, and the research develops an innovative methodology employing micro-computer based spreadsheets, to demonstrate how a series of financial models can be used to quantify the effects of new investments upon overall company performance. Case studies include: the development of a prototype machine based absorption costing system to assist in the evaluation of CNC machine tool purchases in a press making company; the economics and strategy of introducing a flexible manufacturing system for the production of ballscrews; and analysing the progressive introduction of computer based printing presses in a packaging and general print company. Complementary insights are also provided from discussion with the management of several other companies which have experienced technological change. The research was conducted as a collaborative CASE project in the Interdisciplinary Higher Degrees Scheme and was jointly funded by the SERC and Gaydon Technology Limited and later assisted by PE-Inbucon. The findings of the research shows that the introduction of new manufacturing technologies usually requires a fundamental rethink of the existing practices of a business. In particular, its implementation is seen as ideally needing to take place as part of a longer term business and manufacturing strategy, but that short term commercial pressures and limited resources often mean that firms experience difficulty in realising this. The use of a spreadsheet based methodology is shown to be of considerable assistance in evaluating new investments, and is seen as being the limit of sophistication that a smaller business is willing to employ. Several points for effective modelling practice are also given, together with an outline of the context in which a modelling approach is most applicable.

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A tanulmány a szakirodalom azon egyre szélesedő részéhez járul hozzá, amely a kis és középvállalatok gyakorlatával, sajátosságaik vizsgálatával foglalkozik. Egy speciális aspektust emel ki, mely a hazai nagyvállalati működésben jelentős fejlődésen ment keresztül azzal, hogy a KKV-k beszerzési sajátosságainak megismerését célozza meg. Az áttekintő kép kialakításához a nemzetközi szakirodalomban elérhető empirikus eredményeket és a BCE-n folyó Versenyképesség Kutatás kérdőíves adatbázisának válaszait dolgozza fel. Olyan kérdéseket emel ki, mint a beszerzés szerepe a KKV-k működésében és az azt befolyásoló tényezők illetve a beszerzési gyakorlat sajátosságai. _________ Small and medium sized enterprises play an important role in every economy. This article aims to contribute to the growing number of literature focusing on SMEs management practice. It highlights a management field, which has gone through a significant development in large companies’ practice as it investigates the purchasing and supplier management related issues. The overview is based on a review of literature and the analysis of the survey database of Competitiveness Research of CUB. It highlights such topics as the role of purchasing in SMEs, factors influencing the perceived importance and the purchasing practice of SME-s.

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Freshwater use is a major concern in the mass production of algae for biofuels. This project examined the use of canal water obtained from the Everglades Agricultural Area as a base medium for the mass production of algae. This water is not suitable for human consumption, and it is currently used for crop irrigation. A variety of canals were found to be suitable for water collection. Comparison of two methods for algal production showed no significant difference in biomass accumulation. It was discovered that synthetic reticulated foam can be used for algal biomass collection and harvest, and there is potential for its application in large-scale operations. Finally, it was determined that high alkaline conditions may help limit contaminants and competing organisms in growing algae cultures.

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Driven by the ever-growing expectation of ubiquitous connectivity and the widespread adoption of IEEE 802.11 networks, it is not only highly demanded but also entirely possible for in-motion vehicles to establish convenient Internet access to roadside WiFi access points (APs) than ever before, which is referred to as Drive-Thru Internet. The performance of Drive-Thru Internet, however, would suffer from the high vehicle mobility, severe channel contentions, and instinct issues of the IEEE 802.11 MAC as it was originally designed for static scenarios. As an effort to address these problems, in this paper, we develop a unified analytical framework to evaluate the performance of Drive-Thru Internet, which can accommodate various vehicular traffic flow states, and to be compatible with IEEE 802.11a/b/g networks with a distributed coordination function (DCF). We first develop the mathematical analysis to evaluate the mean saturated throughput of vehicles and the transmitted data volume of a vehicle per drive-thru. We show that the throughput performance of Drive-Thru Internet can be enhanced by selecting an optimal transmission region within an AP's coverage for the coordinated medium sharing of all vehicles. We then develop a spatial access control management approach accordingly, which ensures the airtime fairness for medium sharing and boosts the throughput performance of Drive-Thru Internet in a practical, efficient, and distributed manner. Simulation results show that our optimal access control management approach can efficiently work in IEEE 802.11b and 802.11g networks. The maximal transmitted data volume per drive-thru can be enhanced by 113.1% and 59.5% for IEEE 802.11b and IEEE 802.11g networks with a DCF, respectively, compared with the normal IEEE 802.11 medium access with a DCF.

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There is a growing recognition of the importance of the commensal intestinal microbiota in the development and later function of the central nervous system. Research using germ-free mice (mice raised without any exposure to microorganisms) has provided some of the most persuasive evidence for a role of these bacteria in gut-brain signalling. Key findings show that the microbiota is necessary for normal stress responsivity, anxiety-like behaviors, sociability, and cognition. Furthermore, the microbiota maintains central nervous system homeostasis by regulating immune function and blood brain barrier integrity. Studies have also found that the gut microbiota influences neurotransmitter, synaptic, and neurotrophic signalling systems and neurogenesis. The principle advantage of the germ-free mouse model is in proof-of-principle studies and that a complete microbiota or defined consortiums of bacteria can be introduced at various developmental time points. However, a germ-free upbringing can induce permanent neurodevelopmental deficits that may deem the model unsuitable for specific scientific queries that do not involve early-life microbial deficiency. As such, alternatives and complementary strategies to the germ-free model are warranted and include antibiotic treatment to create microbiota-deficient animals at distinct time points across the lifespan. Increasing our understanding of the impact of the gut microbiota on brain and behavior has the potential to inform novel management strategies for stress-related gastrointestinal and neuropsychiatric disorders.