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Showing papers on "Energy source published in 1989"


Book
01 Jan 1989
TL;DR: The aim of the European Wind Atlas is to establish the meteorological basis for the assessment of wind energy resources as mentioned in this paper, and the main objective is to provide suitable data for evaluating the potential wind energy output from large electricity producing wind turbine installations.
Abstract: The aim of the European Wind Atlas is to establish the meteorological basis for the assessment of wind energy resources. The main objective is to provide suitable data for evaluating the potential wind energy output from large electricity producing wind turbine installations. In addition, the Wind Atlas provides data and guidelines for the meteorological aspects of the detailed siting of large and small wind turbines. The EUROPEAN WIND ATLAS IS: A DATA BANK of European Wind climate. It contains comprehensive statistics from more than 200 meteorological stations covering the intire EC - plus colour maps of the wind resources of each country in the EC. The statistical data are given also on a diskette for use with IBM compatible PC's. A HANDBOOK for regional wind resource assessment, and the local siting of wind turbines - including guidelines with computational procedures for the effects of shelter from buildings and other obstacles, the effects of varying surface roughnesses, and for the influence of hills and mountains on the wind climate and on the local wind power resources. A METHODOLOGY description. The computational procedures employed for the analysis of the meteorological data are described in full. These methods have applications for all parts of the world. The computer codes are available separately in the form of the Wind Atlas analysis and Application (PC-) Programme (WAsP). (author).

752 citations


Journal ArticleDOI
TL;DR: Physical conditioning results in an adaptation such that all indicators of damage are reduced following repeated bouts of exercise, and investigators have suggested that the prophylactic effect of training may be due to performance of a single initial exercise bout.
Abstract: Novel, unaccustomed exercise has been shown to result in temporary, repairable skeletal muscle damage. After exhaustive endurance exercise, muscle damage can be produced by metabolic disturbances associated with ischaemia. Extensive disruption of muscle fibres also occurs after relatively short term eccentric exercise where high mechanical forces are generated. Biopsies taken after repetitive eccentric muscle actions have revealed broadening, streaming and, at times, total disruption of Z-discs. Muscles that develop active tension eccentrically also become sore, lose inherent force-producing capability, and show a marked release of muscle proteins into the circulation. Because creatine kinase (CK) is found almost exclusively in muscle tissue, it is the most common plasma marker of muscle damage. Despite the universal use of CK as a marker, several factors with regard to efflux and clearance remain unexplained. Also the large intersubject variability in response to exercise complicates its interpretation. Damage progresses in the postexercise period before tissues are repaired. However, the mechanism to explain exercise-induced muscle damage and repair is not well defined. Among the factors that may influence the damage and repair processes are calcium, lysosomes, connective tissue, free radicals, energy sources, and cytoskeletal and myofibrillar proteins. Physical conditioning results in an adaptation such that all indicators of damage are reduced following repeated bouts of exercise. Recently, investigators have suggested that the prophylactic effect of training may be due to performance of a single initial exercise bout. Following a second bout of exercise performed 1 to 6 weeks after the first bout, there is a reduction in morphological alterations and performance decrements and a profoundly reduced elevation in plasma CK levels. Several hypotheses have been presented to explain the repeated bout or rapid training effect. Stress-susceptible fibres may be eliminated or susceptible areas within a fibre may undergo necrosis and then regenerate. These regenerated fibres, along with adaptations in the connective tissue, may provide greater resistance to further insult.

631 citations


Journal Article
TL;DR: The advantages of nuclear fusion as an energy source and research progress in this area are summarized in this article, where the current state of the art is described, including the Compact Ignition Tokamak (CIT), International Thermonuclear Experimental Reactor (ITER), and a US design called TIBER II.
Abstract: The advantages of nuclear fusion as an energy source and research progress in this area are summarized. The current state of the art is described. Laser fusion, inertial confinement fusion, and magnetic fusion (the tokamak) are explained, the latter in some detail. Remaining problems and planned future reactors are considered. They are the Compact Ignition Tokamak (CIT), the International Thermonuclear Experimental Reactor (ITER), and a US design called TIBER II. The design of the latter is shown. >

596 citations


Book ChapterDOI
TL;DR: Ion-concentration gradients across cell membranes are central to any understanding of biological energetics and signal transduction and the characterization of ion gradients requires knowing both extracellular and intracellular ion activities and free concentrations.
Abstract: Publisher Summary Ion-concentration gradients across cell membranes are central to any understanding of biological energetics and signal transduction. The proton electrochemical gradient is generally accepted to be the key intermediary linking electron transport to adenosine triphosphate (ATP) synthesis in bacteria, chloroplasts, and mitochondria. Cytoplasmic pH is a powerful regulator of enzyme activities and is known to alkalinize in many types of cells undergoing mitogenic activation. The characterization of ion gradients requires knowing both extracellular and intracellular ion activities and free concentrations. The Na+ gradient is the energy source for secondary active transport of nutrients into animal cells and many co- or counter-transport systems for other ions. Cl- gradients are vital to the function of epithelia, the control of cell volume, and to the actions of many inhibitory neurotransmitters. Determination of extracellular ions usually poses much less of a problem than intracellular, because the extracellular medium is much more accessible. Extracellular concentrations of all the simple inorganic ions except K+ are comparable to or higher than intracellular, so detection is easier extracellularly.

414 citations


Journal ArticleDOI
TL;DR: The results indicated that TCE oxidation is not a common property of broad-specificity microbial oxygenases and one new unique class of microorganisms removed TCE from incubation mixtures.
Abstract: Microorganisms that biosynthesize broad-specificity oxygenases to initiate metabolism of linear and branched-chain alkanes, nitroalkanes, cyclic ketones, alkenoic acids, and chromenes were surveyed for the ability to biodegrade trichloroethylene (TCE). The results indicated that TCE oxidation is not a common property of broad-specificity microbial oxygenases. Bacteria that contained nitropropane dioxygenase, cyclohexanone monooxygenase, cytochrome P-450 monooxygenases, 4-methoxybenzoate monooxygenase, and hexane monooxygenase did not degrade TCE. However, one new unique class of microorganisms removed TCE from incubation mixtures. Five Mycobacterium strains that were grown on propane as the sole source of carbon and energy degraded TCE. Mycobacterium vaccae JOB5 degraded TCE more rapidly and to a greater extent than the four other propane-oxidizing bacteria. At a starting concentration of 20 microM, it removed up to 99% of the TCE in 24 h. M. vaccae JOB5 also biodegraded 1,1-dichloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, and vinyl chloride.

294 citations


MonographDOI
31 Jul 1989
TL;DR: In this paper, the authors report on lignins, irregular phenylpropane biopolymers that make up approximately 20-30% of the available polymeric content of hardwood tree stems.
Abstract: This books reports on lignins, irregular phenylpropane biopolymers that make up approximately 20-30% of the available polymeric content of hardwood tree stems. In plants, lignin is second in natural abundance only to cellulose. This material offers, therefore, a valuable resource that must be utilized if the full value of harvested tree crops is to be attained. The yearly growth of the world forests is about 7-9 billion cubic meters of biomass. During the production of 140 million tons of cellulose and pulp from a part of this biomass, about 50 million tons of lignin are formed. Over 95% of the lignin is used as an energy source to operate pulping mills.

246 citations


Journal ArticleDOI
TL;DR: The results demonstrate the metabolic flexibility of R. rubrum to form many different types of polyesters which might substitute plastics synthesized from petrochemicals.

235 citations


Journal ArticleDOI
21 Jul 1989-Science
TL;DR: Model calculations of source partitioning based on the carbon-14 data, CH4 concentrations, and δ13C in CH4 indicate that 21 � 3% of atmospheric CH4 was derived from fossil carbon at the end of 1987, and data indicate that pressurized water reactors are an increasingly important source of 14CH4.
Abstract: Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in "clean air" samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, pat bogs, rice fields, and tundra is somewhat, depleted in carbon-14. Atmospheric (14)GH(4) seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 +/- 0.8 percent modern carbon (pMC) in the Northern Hemisphere and 120.0 +/- 0.7 pMC in the Southern Hemisphere. Model calculations of source partitioning based on the carbon-14 data, CH(4) concentrations, and delta(13)C in CH(4) indicate that 21 +/- 3% of atmospheric CH(4) was derived from fossil carbon at the end of 1987. The data also indicate that pressurized water reactors are an increasingly important source of (14)CH(4).

235 citations


Journal ArticleDOI
TL;DR: The literature related to degradation of atrazine and related s‐triazines is reviewed, with particular emphasis on those substances formed along the degradative pathways and to the biodegradation aspects of mineralization.
Abstract: Atrazine, simazine, and propazine are closely related herbicides that can be used for weed control. The degradation of s‐triazines in soil, water, and sediments has received considerable attention. In this review, the literature related to degradation of atrazine and related s‐triazines is reviewed. Particular emphasis is directed toward those substances formed along the degradative pathways and to the biodegradation aspects of mineralization. The s‐triazines are unusual in that the carbon and nitrogen ring contains no available electrons for aerobic biodegradation. The only sources of energy for aerobic biodegradation of atrazine are found on the ethyl and isopropy I groups. There is some evidence to support the concept that dealkylation of s‐triazines occurs to support the bioenergetic needs of microorganisms. Biodegradation studies with simazine or atrazine as the carbon and energy source have generally shown biodegradation of the alkyl side chains with evolution of radioactive carbon dioxide from chai...

228 citations


Journal ArticleDOI
TL;DR: This paper argues that meat may actually have been a relatively marginal source of sustenance for early hominids, because physiological limits to total protein intake, scarcity of fat in most African ungulates, and comparatively high levels of protein in many plant foods, acted together to maintain their total meat intakes at modest levels, particularly during seasonal or inter-annual periods of resource stress.

214 citations


Journal ArticleDOI
TL;DR: Cultures with H2 as energy source resulted in the enrichment of chemolithotrophic homoacetogenic bacteria whenever incubation temperatures were lower than 20°C, and Hydrogenotrophic methanogens could only be enriched at 30°C from anoxic paddy soil.
Abstract: The effect of temperature on CH4 production, turnover of dissolved H2, and enrichment of H2-utilizing anaerobic bacteria was studied in anoxic paddy soil and sediment of Lake Constance. When anoxic paddy soil was incubated under an atmosphere of H2/CO2, rates of CH4 production increased 25°C, but decreased at temperatures lower than 20°C. Chloroform completely inhibited methano-genesis in anoxic paddy soil and lake sediment, but did not or only partially inhibit the turnover of dissolved H2, especially at low incubation temperatures. Cultures with H2 as energy source resulted in the enrichment of chemolithotrophic homoacetogenic bacteria whenever incubation temperatures were lower than 20°C. Hydrogenotrophic methanogens could only be enriched at 30°C from anoxic paddy soil. A homoacetogen

Journal ArticleDOI
TL;DR: Neither growth values nor retention values for protein and fat indicated that carbohydrate was utilized to any significant degree as a source of energy.

Patent
06 Jul 1989
TL;DR: In this paper, a method and apparatus for removing surface contaminants from the surface of a substrate by high-energy irradiation is described, which enables removal of surface contaminants without altering the substrate's underlying molecular structure.
Abstract: A method and apparatus for removing surface contaminants from the surface of a substrate by high-energy irradiation is provided. The invention enables removal of surface contaminants without altering of the substrate's underlying molecular structure. The source of high-energy irradiation may comprise a pulsed laser.

Journal ArticleDOI
TL;DR: These results establish that cellular death is accompanied by complete disruption of bacterial ATP production by both oxidative and fermentative pathways as a consequence of inhibition of inner membrane bound systems responsible for these processes.
Abstract: The adenylate energy charges (EC) of Escherichia coli 25922, Pseudomonas aeruginosa 27853, and Streptococcus lactis 7962 rapidly fell in nutrient-rich media from values in excess of 0.9 to below 0.1 when the organisms were exposed to lethal levels of HOCl. The same cells maintained in energy-depleted states were incapable of attaining normal EC values necessary for biosynthesis and growth when challenged with nutrient energy sources after HOCl exposure. These changes correlated quantitatively with loss of replicative capabilities. Initial rates of transport of glucose, succinate, and various amino acids that act as respiratory substrates and the ATP hydrolase activity of the F1 complex from the ATP synthase of E. coli 25922 also declined in parallel with or preceded loss of viability. These results establish that cellular death is accompanied by complete disruption of bacterial ATP production by both oxidative and fermentative pathways as a consequence of inhibition of inner membrane bound systems responsible for these processes.

Journal ArticleDOI
TL;DR: It is proposed that free amino acids (FAA) are an important energy source during embryonic development of marine fishes and an exogenous supply of FAA seems necessary when the reserves of the larva are depleted.

Journal ArticleDOI
TL;DR: In this article, the authors summarize the current understanding of several important types of stability in the food web and describe the theoretical and empirical evidence relating them to nutrient limitation and nutrient cycling.
Abstract: The importance of nutrient limitation and recycling in ecosystems is widely recognized. Nutrients, defined in the broad sense as all material elements vital to biological functions, are in such small supply that they limit production in many ecosystems. Such limitation can affect ecosystem properties, including the structure and dynamics of the food webs that link species through their feeding relationships. What are the effects of limiting nutrients on the stability of ecosystem food webs Most of the literature on food web stability centers around the dynamics of population numbers and/or biomasses. Nevertheless, a growing body of theoretical and empirical research considers the role that both nutrient limitation and recycling can play in stability. In this paper, it is the authors objective to summarize the current understanding of several important types of stability. The theoretical and empirical evidence relating these types of stability and nutrient cycling is described. A central generalization is produced in each case.

Journal ArticleDOI
TL;DR: The irregularly shaped cells and short rods were present at less than 10(9)/ml in vivo, but they ahd very high specific activities of ammonia production and could play an important role in ruminal amino acid fermentation.
Abstract: Two monensin-sensitive bacteria which utilized carbohydrates poorly and grew rapidly on amino acids were isolated from the bovine rumen. The short rods (strain SR) fermented arginine, serine, lysine, glutamine, and threonine rapidly (greater than 158 nmol/mg of protein per h) and grew faster on casein digest containing short peptides than on free amino acids ().34 versus 0.29 h(-1)). Gelatin hydrolysate, an amino acid source containing an abundance of long peptides, was unable to support growth or ammonia production, but there was a large increase in ammonia production if strain SR was cocultured with peptidase-producing ruminal bacteria (Bacteroides ruminicola or Streptococcus bovis). Cocultures showed no synergism with short peptides. Strain SR washed out of continuous culture ().1 h(-1)) at pH 5.9. The irregularly shaped organisms (strain F) deaminated glutamine, histidine, glutamate, and serine rapidly (greater than 137 nmol/mg of protein per min) and grew faster on free amino acids than on short peptides ().43 versus 0.21 h(-1)). When strain F was provided with casein or gelatin hydrolysate and cocultured with peptidase-producing bacteria, there was a more than additive increase in ammonia production. Strain F grew in continuous culture (0.1 h(-1)) when the pH was as low as 5.3. The irregularly shaped cells and short rods were present at less than 10(9)/ml in vivo, but they ahd very high specific activities of ammonia production (greater than 310 nmol of ammonia/mg of protein per min) and could play an important role in ruminal amino acid fermentation.

Patent
07 Jun 1989
TL;DR: In this article, the authors describe a medical device that applies localized heat to a site in a patient's body by irradiation with light and conduction by conduction, where a high intensity light such as laser is transmitted into a body cavity, typically the uterus.
Abstract: A medical device (10) applies localized heat to a site in a patient's body by irradiation with light and by conduction. The device includes a radiant energy transmitting conduit (22) typically an optic fiber, that carries radiant energy, typically high intensity light such as laser, into a body cavity, typically the uterus (100), from an energy source (50) typically a laser source that is located exterior to the body through the conduit (22) and out a bulbous element (18). At the operative head of the device a portion of the transmitted radiant energy is absorbed and converted to heat and another portion of the transmitted radiant energy is emitted through an aperture in the device head as light energy suitable for more localized an intense heating and destruction of tissue.

Journal ArticleDOI
TL;DR: It is concluded that in general there are two major concerns: in those sports in which body composition plays an important role, energy and thus nutrient intake is often marginal and in all groups of athletes intake of carbohydrate is insufficient.
Abstract: Information about habitual food intake was systematically obtained from elite endurance, strength, and team sport athletes. The athletes (n = 419) trained at least 1-2 h daily and competed on an international level. A 4- or 7-day food diary was kept. For analysis of the data, a computerized food table was used. Mean energy intake varied from 12.1-24.7 MJ per day for male and 6.8-12.9 MJ per day for female athletes. Protein intake was in agreement with or higher than the Dutch recommendations. Contribution of carbohydrate intake to total energy intake varied from 40%-63%. Fat intake tended to meet the criteria for a prudent diet (less than 35%). Snacks contributed about 35% to the total energy intake and the bread/cereals and dairy food groups were the most important energy sources. It is concluded that in general there are two major concerns. In those sports in which body composition plays an important role, energy and thus nutrient intake is often marginal. In all groups of athletes intake of carbohydrate is insufficient.

Journal ArticleDOI
26 May 1989-Science
TL;DR: A group transfer reaction is proposed that forms a retinyl ester from a lipid acyl donor and vitamin A and the prediction of an obligate C-O bond cleavage in the vitamin A moiety during isomerization is borne out.
Abstract: The eye needs to biosynthesize 11-cis-retinoids because the chromophore of rhodopsin is 11-cis-retinal. The critical metabolic step is the endergonic isomerization of free all-trans-retinol (vitamin A) into 11-cis-retinol. This isomerization process can take place in isolated membranes from the retinal pigment epithelium in the absence of added energy sources. Specific binding proteins probably do not serve as an energy source, and since all of the reactions in the visual cycle are shown here to be reversible, trapping reactions also do not participate in the isomerization reaction. One previously unexplored possibility is that the chemical energy in the bonds of the membrane itself may drive the isomerization reaction. A group transfer reaction is proposed that forms a retinyl ester from a lipid acyl donor and vitamin A. This transfer can drive the isomerization reaction because the all-trans-retinyl ester is isomerized directly to 11-cis-retinol. Thus, the free energy of hydrolysis of the ester is coupled to the thermodynamically uphill trans to cis isomerization. The prediction of an obligate C-O bond cleavage in the vitamin A moiety during isomerization is borne out. Although the natural substrate for isomerization is not known, all-trans-retinyl palmitate is processed in vitro to 11-cis-retinol by pigment epithelial membranes.

Journal ArticleDOI
TL;DR: In this article, the authors provided a broad overview of the use of plant material as a source of usable energy and discussed the problem of gathering and interpreting data on the usage of biomass.
Abstract: This paper provides a broad overview of the use of plant material as a source of usable energy. The problem of gathering and interpreting data on the use of biomass is discussed. From the limited data available it is inferred that bio energy contributes about 15% of the global energy budget. The paper deals with a variety of other major topics: the role of biomass in the energy system, differences in that role in industrialized and developing countries, conversion technologies, environmental considerations and the multiple uses of biomass (food for people, feed for animals and fibre for construction material and other uses as well as energy sources). The ability of the biosphere to provide adequate amounts of primary energy is limited, especially if forecasts of population growth, and associated increases in the demand for food, feed and fibre, turn out to be accurate. By improving the efficiency ofbioenergy use, which is currently very low, it should be possible to deliver more tertiary energy for the same primary energy input.

Journal ArticleDOI
TL;DR: The ability of this community to utilize a high-molecular-weight PAH as the sole carbon source, in conjunction with its ability to transform a diverse array of PAHs, suggests that it may be of value in the bioremediation of environments contaminated with PAHS, such as those impacted by creosote.
Abstract: Cultures enriched by serial transfer through a mineral salts medium containing fluoranthene were used to establish a stable, seven-member bacterial community from a sandy soil highly contaminated with coal tar creosote. This community exhibited an ability to utilize fluoranthene as the sole carbon source for growth, as demonstrated by increases in protein concentration and changes in absorption spectra when grown on fluoranthene in liquid culture. Biotransformation of other polycyclic aromatic hydrocarbons (PAHs) was verified by demonstrating their disappearance from an artificial PAH mixture by capillary gas chromatography. When grown on fluoranthene as the sole carbon source and subsequently exposed to fluoranthene plus 16 additional PAHs typical of those found in creosote, this community transformed all PAHs present in this defined mixture. After 3 days of incubation, 13 of the original 17 PAH components were degraded to levels below the limit of detection (10 ng/liter). Continued incubation resulted in extensive degradation of the remaining four compounds. The ability of this community to utilize a high-molecular-weight PAH as the sole carbon source, in conjunction with its ability to transform a diverse array of PAHs, suggests that it may be of value in the bioremediation of environments contaminated with PAHs, such as those impacted by creosote.

Journal ArticleDOI
TL;DR: In this article, the systematics of stable-isotope exchange between minerals and fluids are examined in the context of modal mineralogical variations and mass-balance considerations, both in closed and in open systems.

Book
15 Jun 1989
TL;DR: In this article, the authors present a model for investigating weathering, migration and close-out of tailings in a mine environment, and evaluate the model's performance in terms of water management, chemical, physical and natural barriers.
Abstract: 1. Mining - The Issues. Introduction. Tailings and waste rock analyses. Disposal. Reclamation. Water recycle. In-plant abatement. Toxicity of effluents. Ongoing research. Concerns of public and legislative bodies. Corporate responsibility. 2. Development of Waste Water Regulations and Guidelines. 3. Influence of the Mining and Mineral Extraction Process. Introduction. Mining. Crushing, grinding, beneficiation and mineralogy. Leaching. Liquid-solids separation. Solution purification and product recovery. Conservation and by-product recovery. Chemistry. Control. 4. Toxicity of Mining and Milling Reagents to the Environment. Introduction. Toxicity of some selected reagents in the milling circuit. Toxicity of some petrochemicals to fish. Reagent biodegradability. Effects of soluble metal-extractant complexes. 5. Tailings Impoundment Selection and Design. Introduction. Tailings and waste rock characteristics. Design of overall treatment system. Impoundment design for tailings. Design for waste dumps. Liners and barriers. 6. Tailings Deposition. Introduction. Deposition methods. 7. Water Management. Criteria. Control of water in the impoundment area. Tailings ponds. Dewatering of tailings. Water recycling and reuse. 8. Monitoring of Tailings Impoundment Site. 9. Sampling and Analysis. Introduction. Sampling. Analyses. Speciation procedure. Analytical techniques for soils. 10. Weathering and Migration Processes. Introduction. Global cycles. Characterization of tailings and waste rock. Hydrogeology influences. Dissolution, precipitation and exchange processes. Eh - pH relationships. Oxidation of sulphides, acid drainage and prevention. Soil development profile. Migration. The ecosystem. Conclusions and summary. 11. Effluent Treatment for Environmental Control. Introduction. Control and prevention of acid mine drainage. Treatment of acidic and other waste waters. Biological and ecological systems. 12. Some Specific Tailings. Decommissioning, Reclamation and Covers. Introduction. Alumina plant tailings. Base metals. Coal. Flotation circuits. Gold. In-situ operations. Iron ore. Oil sands tailings. Phosphate rock. Potash. Sand and gravel. Titanium. Uranium. 13. Decommissioning, Reclamation and Covers. Introduction. Covers. Possible close-out options. Conclusion. 14. Methodology and Plan for Investigating Weathering, Migration and Close-Out - The Model. Introduction. Source terms. The model. Weathering and migration studies. Modelling. Chemical, physical and natural barriers. Examination of tailings and/or waste rock for eventual cover and close-out: summary. 15. Costs of Disposal Options and Management. Introduction. Tailings treatment in mill. Slurry thickening. Slurry transport. Tailings impoundment. Effluent treatment. Effluent transport and/or evaporation. Restoration of tailings area. Sampling and analysis. Evaluation of costs. Appendix I. Conversion units. Subject Index.

Journal ArticleDOI
01 Sep 1989-Genetics
TL;DR: This work has suggested that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source, since other common duplications that include the permease are not selected.
Abstract: Duplication-containing cells are selected when growth of Salmonella typhimurium is limited by the availability of any one of several carbon and energy sources. Under conditions of extreme starvation, growth occurs almost exclusively in the duplication-containing fraction of the population. Cells with duplications of one large segment of the chromosome are repeatedly selected regardless of which of these carbon sources limits growth. The duplicated chromosomal segment encodes the transport systems for all of these carbon sources. This duplication is not selected during growth on a carbon source for which the permease is not included within the duplication segment. This suggests that the growth advantage conferred by the duplication may be due to increased transport of the limiting carbon source. Inclusion of the permease alone is not sufficient to explain the growth advantage of the duplications, since other common duplications that include the permease are not selected.

Journal ArticleDOI
TL;DR: Five Hereford × Angus steers with chronic indwelling catheters in various sites in the splanchnic bed were used to evaluate effects of dietary energy source and nitrogen level on urea synthesis and site and rate of urea removal from blood.
Abstract: Five Hereford × Angus steers, 240 ± 6 kg liveweight with chronic indwelling catheters in various sites in the splanchnic bed were used to evaluate effects of dietary energy source and nitrogen (N) level on urea synthesis and site and rate of urea removal from blood. Alfalfa hay (162 g N d−1) or a high concentrate diet (95 g N d−1) were fed at similar metabolizable energy intake (54.8 MJ d−1). Compared with the alfalfa, the high concentrate, low N diet decreased (P 0.10) by diet. A greater (...

Journal ArticleDOI
TL;DR: The data support the classical view that amino acids and protein do not contribute substantially as an energy source during exercise, since in trained individuals significant increases in the activity of the BC-complex occur only after prolonged intense exercise.
Abstract: The present study was conducted to investigate the metabolic regulation of the oxidation of branched-chain amino acids (BCAA) by exercise in human skeletal muscle. Five trained male volunteers were exercised on a cycle ergometer at 70% +/- 10% (mean +/- SD) of their maximal oxygen consumption (VO2max). Percutaneous quadriceps muscle biopsies were obtained under local anaesthesia at rest and after 30 and 120 min of exercise. In the muscle samples the active and total amount of the branched-chain 2-oxo acid dehydrogenase complex (BC-complex), the regulatory enzyme in the oxidative pathway of the BCAA, were measured. Glycogen content and activity of mitochondrial marker enzymes were also measured. Blood samples were obtained every 20 min for the measurement of metabolites. Heart rate and rated perceived exertion on the Borg scale were recorded every 10 min. At rest 4.0% +/- 2.5% of the BC complex was active, after 30 min of exercise 9.9% +/- 9.0% and after 120 min 17.5% +/- 8.5% (mean +/- SD). Exercise did not change the total activity. The largest activation was seen in two of the subjects who developed higher blood lactates early on during exercise and decreased their muscle glycogen more (indications of anaerobic metabolism). These data demonstrate that in trained individuals significant increases in the activity of the BC-complex occur only after prolonged intense exercise. In spite of the 4-fold activation, the data support the classical view that amino acids and protein do not contribute substantially as an energy source during exercise, since VO2 increased more than 20-fold.

Journal ArticleDOI
TL;DR: In this article, a comparison of the dynamo solutions of both, dipolar and quadrupolar, symmetries with the corresponding non-magnetic solutions showed a strong increase of the amplitude of convection owing to the release of the rotational constraint by the Lorentz force.
Abstract: Finite amplitude solutions for magnetohydrodynamic dynamos driven by convection in rotating spherical fluid shells with a radius ratio of ηequals; 0.4 are obtained numerically by the Galerkin method. Solutions which are twice periodic in the azimuth (case m equals; 2) are emphasized, but a few cases with higher azimuthal wavenumber have also been considered. An electrically insulating space outside the fluid shell has been assumed. A comparison of the dynamo solutions of both, dipolar and quadrupolar, symmetries with the corresponding non-magnetic solutions shows a strong increase of the amplitude of convection owing to the release of the rotational constraint by the Lorentz force. In some cases at low Taylor number the amplitude of convection is decreased, however, owing to the competition of the magnetic degree of freedom for the same energy source. The strength of differential rotation is usually reduced by the Lorentz force, especially in the case of quadrupolar dynamos which differ in this r...

Journal ArticleDOI
TL;DR: Enzyme activities and growth properties of Pseudomonas strains harbouring this fragment indicate that phenol hydroxylase is a multicomponent enzyme containing the 39.5 kDa polypeptide as one component.
Abstract: Pseudomonas strain CF600 is able to utilize phenol and 3,4-dimethylphenol as sole carbon and energy source. We demonstrate that growth on these substrates is by virtue of plasmid-encoded phenol hydroxylase and a meta-cleavage pathway. Screening of a genomic bank, with DNA from the previously cloned catechol 2,3-dioxygenase gene of the TOL plasmid pWW0, was used in the identification of a clone which could complement a phenol-hydroxylase-deficient transposon insertion mutant. Deletion mapping and polypeptide production analysis identified a 1.2 kb region of DNA encoding a 39.5 kDa polypeptide which mediated this complementation. Enzyme activities and growth properties of Pseudomonas strains harbouring this fragment on a broad-host-range expression vector indicate that phenol hydroxylase is a multicomponent enzyme containing the 39.5 kDa polypeptide as one component.

Journal ArticleDOI
TL;DR: In this paper, the basic AGN characteristics (broad emission lines of abundant ions, X-ray emission, and a sharp starlike appearance) are summarized, and particular attention is given to the spectral classification of Seyfert galaxies, the AGN velocity fields and their measurement, low-ionization narrow-emission-line regions (LINERs), observations supporting a torus model of SeYfert AGN, extended gas and ionization, and the black-hole/accretion-disk model of the energy source.
Abstract: Recent observational and theoretical investigations of AGN are reviewed. The basic AGN characteristics (broad emission lines of abundant ions, X-ray emission, and a sharp starlike appearance) are summarized, and particular attention is given to the spectral classification of Seyfert galaxies, the AGN velocity fields and their measurement, low-ionization narrow-emission-line regions (LINERs), observations supporting a torus model of Seyfert AGN, extended gas and ionization, and the black-hole/accretion-disk model of the AGN energy source. It is suggested that no one model can explain the physical processes in all types of AGN. 43 refs.