1,314 research outputs found

    New Frontiers and Perspectives in Grassland Technology

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    Grassland scientists and farmers are increasingly faced with emerging new technologies and in-formation systems that have been primarily developed by engineering sciences in particular: precision agriculture, remote sensing, geographic localization and biotechnology. Whether the implementation of any of these technologies may be beneficial in economic and ecological respect is a challenging judgment call, especially for those who have to carry over that decision on their farm. Compared to arable land, new technologies have been applied on grassland only partially and with some delay. However, as we will demonstrate, there is place for a successful implementation of new technologies in various climate regions and for a wide range of applications. This paper presents the most significant and recent developments of new technologies in agriculture that have a potential for beneficial application on grassland. It defines the relevant terms and processes, provides examples of successful implementation and discusses future orientations and research needs

    Agriculture-induced changes in mycorrhizal fungal assemblages: Implications for ecological risk assessment of transgenic crops

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    Heijden, M.G.A. van der [Promotor]Verhoef, H.A. [Promotor]Röling, W.F.M. [Copromotor]Kiers, E.T. [Copromotor

    Hunting for nuclear markers in green algal lineages: molecular evolution of glucose-6-phosphate isomerase

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    The Chlorophyta exhibit a remarkable cytological diversity ranging from unicellular microscopic algae with a single nucleus, over multicellular filaments and foliose blades, to coencytic and even siphonous life forms that are essentially composed of a giant cell containing thousands of nuclei. Unravelling the evolutionary history of this diverse and evolutionary old group is a difficult task due to the antiquity of the major lineages and considerable rate variation between those lineages for the commonly used 18S ribosomal DNA sequences and chloroplast markers (Lewis et al., Therefore different genes with known function and sequence data available are tested and more recently a cDNA library is screened to search for new useful genes.Glucose-6-phosphate isomerase (G6PI) is one of the genes we are testing. It is an important enzyme of the carbohydrate biosynthesis pathway in photosynthetic organisms and of the glycolysis in all organisms. Little is known about copy number of the gene in the Chlorophyta. The complete genome sequences of Chlamydomonas reinhardtii and Ostreococcus taur revealed that both have a single copy of G6PI. In plants however within a single genus there are species with one G6PI gene and other species with two G6PI (e.g. Arabidopsis, Actinidia,…) and up to thre copies are observed in Zea mays. It always concerns recent duplication within one genus.To investigate if the G6PI gene(s) is useful as a phylogenetic marker in the Chlorophyta, primers were made based on the G6PI genome sequences of Arabidopsis thaliana, Oryza sativa, Chlamydomonas reinhardtii and Ostreococcus tauri. The primers were tested on DNA and RNA of a variety of green algae.Following conclusions can be drawn from these preliminary results: 1. epiphytic or endophytic bacteria interfere with the direct amplification of nuclear genes; 2. the G6PI gene is informative on several taxonomic levels: for deep phylogenies we have to use a codon substitution model, for species level relationships introns may offer opportunities towards studies at the interspecific level; 3. most likely only one (functional) copy of the G6PI gene is present in the tested taxa

    Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: homogeneous/inhomogeneous transition of current distribution

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    Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3, NiO, and CoO. The sandwich exhibits a resistance that reversibly switches between two states: one is a highly resistive off-state and the other is a conductive on-state. Several distinct features were universally observed in these binary TMO sandwiches: namely, nonpolar switching, non-volatile threshold switching, and current--voltage duality. From the systematic sample-size dependence of the resistance in on- and off-states, we conclude that the resistance switching is due to the homogeneous/inhomogeneous transition of the current distribution at the interface.Comment: 7 pages, 5 figures, REVTeX4, submitted to Phys. Rev. B (Feb. 23, 2007). If you can't download a PDF file of this manscript, an alternative one can be found on the author's website: http://staff.aist.go.jp/i.inoue

    Superconductor-insulator transition in nanowires and nanowire arrays

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    Superconducting nanowires are the dual elements to Josephson junctions, with quantum phase-slip processes replacing the tunneling of Cooper pairs. When the quantum phase-slip amplitude ES is much smaller than the inductive energy EL, the nanowire responds as a superconducting inductor. When the inductive energy is small, the response is capacitive. The crossover at low temperatures as a function of ES/EL is discussed and compared with earlier experimental results. For one-dimensional and two-dimensional arrays of nanowires quantum phase transitions are expected as a function of ES/EL. They can be tuned by a homogeneous magnetic frustration.Comment: 15 pages, 10 figure

    Cross-cultural adaptation of the Dutch version of the Functional Index for Hand Osteoarthritis (FIHOA) and a study on its construct validity

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    SummaryObjectiveTo validate a cross-culturally translated and adapted Dutch version of the Functional Index for Hand Osteoarthritis (FIHOA) in patients with osteoarthritis (OA) of the hands and to evaluate its construct validity by comparing with the Australian/Canadian Osteoarthritis Hand Index (AUSCAN).MethodsThe FIHOA was translated into Dutch and cross-culturally adapted. The questionnaire was administered to 72 patients with hand OA (female/male ratio: 64/8, handedness: right: 62/left: 7/both: 3). A visual analogue scale (VAS) pain scale (100mm) and the AUSCAN questionnaire were also recorded. An item–item analysis was performed. Test–retest reliability (time interval: 5 days) was assessed in 21 patients with intraclass correlation coefficient (ICC) and Bland and Altman graphical method. Construct validity was assessed by Spearman rank correlation coefficient between the FIHOA and AUSCAN.ResultsInternal consistency was high (Cronbach's alpha=0.89). All items, except for one (‘Are you able to clench the fist?’), and the mean total FIHOA scores were statistically different between the subgroups based on the VAS (mean total score=7.46 and 14.19, in a-/mild symptomatic and symptomatic group, respectively (P<0.001)).The Spearman's correlation between all subscales of the AUSCAN (pain, stiffness, functionality) and the FIHOA was good, especially with the subscale functionality (r=0.81, P<0.01). Test–retest reliability was excellent with an ICC of 0.96 for the total score and the Bland and Altman plot showing a homogeneous distribution of the differences.ConclusionThe psychometric properties of the Dutch version of the FIHOA are excellent. There is a good correlation between the FIHOA and all subscales of the AUSCAN, especially the subscale functionality

    Determination of antioxidant activity of polyphenol extract from grape seeds

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    The significance of carbohydrates for endurance training has been well established, whereas the role of protein and the adaptive response with endurance training is unclear. Therefore, the aim of this perspective is to discuss the current evidence on the role of dietary protein and the adaptive response with endurance training. On a metabolic level, a single bout of endurance training stimulates the oxidation of several amino acids. Although the amount of amino acids as part of total energy expenditure during exercise is relatively low compared to other substrates (e.g., carbohydrates and fat), it may depress the rates of skeletal muscle protein synthesis, and thereby have a negative effect on training adaptation. A low supply of amino acids relative to that of carbohydrates may also have negative effects on the synthesis of capillaries, synthesis and turn-over of mitochondrial proteins and proteins involved in oxygen transport including hamoglobin and myoglobin. Thus far, the scientific evidence demonstrating the significance of dietary protein is mainly derived from research with resistance exercise training regimes. This is not surprising since the general paradigm states that endurance training has insignificant effects on skeletal muscle growth. This could have resulted in an underappreciation of the role of dietary protein for the endurance athlete. To conclude, evidence of the role of protein on endurance training adaptations and performance remains scarce and is mainly derived from acute exercise studies. Therefore, future human intervention studies must unravel whether dietary protein is truly capable of augmenting endurance training adaptations and ultimately performance

    «Через край із серця рідне слово ллється…» (про мову поезій П. Куліша)

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    Several studies have shown that soil biotic communities from organically managed fields are more diverse and exhibit higher activity levels compared to conventionally managed fields. The impact of these different soil communities on plant productivity and the provision of soil ecosystem services are, however, still unclear. Here, we test the effects of soil inoculation from each of three organic and three conventional maize fields on maize productivity and nutrient loss during leaching events induced by simulated rain. In particular, we examine whether differences in productivity and nutrient loss are related to the abundance and species composition of arbuscular mycorrhizal (AM) fungi. We hypothesized that soil biota from organically managed fields would improve maize growth and reduce nutrient leaching significantly more than those from conventionally managed fields. In contrast to our hypothesis, we found that plant productivity was negatively affected by soil inoculation, and this effect was stronger with inoculum from organic fields. Plant productivity was inversely correlated with AMF abundance, suggesting that enhanced carbon allocation to AMF is at least in part responsible for plant growth reduction under our experimental conditions. However, soil inoculation did alter the ecological functioning of the system by reducing phosphorus leaching losses after simulated rain. Moreover, these leaching losses were lower with increased hyphal density and were related with abundance of particular AMF types, suggesting that abundance of AMF and their community composition may be useful indicators of phosphorus leaching losses. The results demonstrate that soil communities from different agricultural fields vary in their impact on plant productivity and nutrient leaching losses. The results further indicate that there is a potential tradeoff between positive effects of soil communities on sustainability and negative effects on crop productivity. © 2011 The Author(s)

    Aharonov-Bohm interference in the presence of metallic mesoscopic cylinders

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    This work studies the interference of electrons in the presence of a line of magnetic flux surrounded by a normal-conducting mesoscopic cylinder at low temperature. It is found that, while there is a supplementary phase contribution from each electron of the mesoscopic cylinder, the sum of these individual supplementary phases is equal to zero, so that the presence of a normal-conducting mesoscopic ring at low temperature does not change the Aharonov-Bohm interference pattern of the incident electron. It is shown that it is not possible to ascertain by experimental observation that the shielding electrons have responded to the field of an incident electron, and at the same time to preserve the interference pattern of the incident electron. It is also shown that the measuring of the transient magnetic field in the region between the two paths of an electron interference experiment with an accuracy at least equal to the magnetic field of the incident electron generates a phase uncertainty which destroys the interference pattern.Comment: 15 pages, 5 Postscript figure
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