The role of selected plant and microbial metabolites in the nutrient solution of closed growing systems in greenhouses

Recirculation of nutrient solution in greenhouse growing systems inhabits environmental and economic advantages regarding saving water and fertilizers. The disadvantages are a greater risk for spread of phytopathogens by the nutrient solution and for accumulation of organic compounds at phytotoxic levels. Organic compounds are excreted as root exudates by the crop as well as by microorganisms in the rhizosphere and are also being released by constituent devices in the growing system. In the present thesis, benzoic, caffeic, chlorogenic, ferulic, p-hydroxybenzoic, salicylic, vanillic acids, phenazine-1-carboxylic acid, pyoluteorin, pyrrolnitrin and 2,4-diacetyl phloroglucinol were studied with respect to occurrence in the nutrient solution of closed hydroponic growing systems, phytotoxic response, persistence and optimised formation. Phytotoxicity levels were studied on young tomato plants exposed to initial concentrations of benzoic, caffeic, chlorogenic, ferulic, p-hydroxybenzoic, salicylic, vanillic acids in the fresh solution. Effects were seen primarily on roots at 200 and 400 µM for most of the compounds. Supported liquid membrane technique was adopted to extract several plant and microbial metabolites in situ in the greenhouse. The method was then used to study the nutrient solution in tomato, cucumber and gerbera crops, which were grown in closed growing systems including artificial infection of root pathogenic fungi and/or selected disinfestation methods, namely slow sand filtration and UV-radiation. They were investigated at different developmental stages and compounds were determined in the range of 10-200 nM in the nutrient solutions. Benzoic acid was found throughout all crops, sampling occasions and treatments. Furthermore, p-hydroxybenzoic acid was determined, as well as occasionally 2,4-diacetyl phloroglucinol, especially in systems with slow sand filter treatment. In vitro, synthetical organic compounds added to effluent nutrient solution disappeared rapidly, mostly within two days. The occurrence of plant and microbial metabolites should rather be regarded as an asset. Optimising the living conditions for the resident microflora in the nutrient solution might favour biocontrol of root pathogens. Increased metabolite production of the control strain was observed. However, low levels of selected microbial metabolites were found after enrichment of the nutrient solution microflora. Preconditions for future studies are discussed

When to rebuild or when to adjust scorecards

Data-based scorecards, such as those used in credit scoring, age with time and need to be rebuilt or readjusted. Unlike the huge literature on modelling the replacement and maintenance of equipment there have been hardly any models that deal with this problem for scorecards. This paper identifies an effective way of describing the predictive ability of the scorecard and from this describes a simple model for how its predictive ability will develop. Using a dynamic programming approach one is then able to find when it is optimal to rebuild and when to readjust a scorecard. Failing to readjust or rebuild a scorecard when they aged was one of the defects in credit scoring identified in the investigations into the sub-prime mortgage crisis

Engaging visitors of science festivals using augmented reality: asymmetrical modelling

Purpose This paper aims to explore a complex combination of four realms of the experience economy in formulating memories and satisfaction among festival visitors by using augmented reality (AR), thus engaging visitors in the physical science experience. This study also identifies necessary conditions to achieve desired responses from visitors. Design/methodology/approach Asymmetrical modelling with fuzzy set qualitative comparative analysis (fsQCA) was used to investigate causal recipes of two configurations of the experience economy and evaluation of experience leading to both high and low scores from visitor engagement. Necessary condition analysis was applied to examine necessary predictors in visitor engagement. The proposed configuration model was tested by using data obtained from visitors to science festivals in the UK. Findings Five causal recipes explained the complex conditions in which visitors were more likely engaged in AR. Aesthetics, education, entertainment and satisfaction were necessary for high engagement among festival visitors. Research limitations/implications The results from fsQCA and analyses of necessary conditions help festival organizers improve visitor satisfaction and engagement in a memorable AR experience. Originality/value This empirical study deepens current festival understanding of how visitors experience AR by exploring combinations of complex configurations of the experience economy and evaluations of visitor experience based on memories and satisfaction. Unlike symmetrical approaches, asymmetrical modelling by using fsQCA can explore recipes for both high and low scores of visitor satisfaction and engagement. This is the first empirical study investigating necessary predictors of festival visitor behaviour

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes

AbstractObjective: To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes.Design: Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1β. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1β-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting.Results: The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100μM of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50μM. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10μM. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1β, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50μM, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level.Conclusions: Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100μM of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss

V-I characteristics in the vicinity of order-disorder transition in vortex matter

The shape of the V-I characteristics leading to a peak in the differential resistance r_d=dV/dI in the vicinity of the order-disorder transition in NbSe2 is investigated. r_d is large when measured by dc current. However, for a small Iac on a dc bias r_d decreases rapidly with frequency, even at a few Hz, and displays a large out-of-phase signal. In contrast, the ac response increases with frequency in the absence of dc bias. These surprisingly opposite phenomena and the peak in r_d are shown to result from a dynamic coexistence of two vortex matter phases rather than from the commonly assumed plastic depinning.Comment: 12 pages 4 figures. Accepted for publication in PRB rapi

Molecular dynamics approach: from chaotic to statistical properties of compound nuclei

Statistical aspects of the dynamics of chaotic scattering in the classical model of $\alpha$-cluster nuclei are studied. It is found that the dynamics governed by hyperbolic instabilities which results in an exponential decay of the survival probability evolves to a limiting energy distribution whose density develops the Boltzmann form. The angular distribution of the corresponding decay products shows symmetry with respect to $\pi/2$ angle. Time estimated for the compound nucleus formation ranges within the order of $10^{-21}$s.Comment: 11 pages, LaTeX, non

Multiple current reversals in forced inhomogeneous ratchets

Transport properties of overdamped Brownian paricles in a rocked thermal ratchet with space dependent friction coefficient is studied. By tuning the parameters, the direction of current exhibit multiple reversals, both as a function of the thermal noise strength as well as the amplitude of rocking force. Current reversals also occur under deterministic conditions and exhibits intriguing structure. All these features arise due to mutual interplay between potential asymmetry,noise, driving frequency and inhomogeneous friction.Comment: 6 figure

Meson screening masses from lattice QCD with two light and the strange quark

We present results for screening masses of mesons built from light and strange quarks in the temperature range of approximately between 140 MeV to 800 MeV. The lattice computations were performed with 2+1 dynamical light and strange flavors of improved (p4) staggered fermions along a line of constant physics defined by a pion mass of about 220 MeV and a kaon mass of 500 MeV. The lattices had temporal extents Nt = 4, 6 and 8 and aspect ratios of Ns / Nt \geq 4. At least up to a temperature of 140 MeV the pseudo-scalar screening mass remains almost equal to the corresponding zero temperature pseudo-scalar (pole) mass. At temperatures around 3Tc (Tc being the transition temperature) the continuum extrapolated pseudo-scalar screening mass approaches very close to the free continuum result of 2 \pi T from below. On the other hand, at high temperatures the vector screening mass turns out to be larger than the free continuum value of 2 \pi T. The pseudo-scalar and the vector screening masses do not become degenerate even for a temperature as high as 4Tc. Using these mesonic spatial correlation functions we have also investigated the restoration of chiral symmetry and the effective restoration of the axial symmetry. We have found that the vector and the axial-vector screening correlators become degenerate, indicating chiral symmetry restoration, at a temperature which is consistent with the QCD transition temperature obtained in previous studies. On the other hand, the pseudo-scalar and the scalar screening correlators become degenerate only at temperatures larger than 1.3Tc, indicating that the effective restoration of the axial symmetry takes place at a temperature larger than the QCD transition temperature.Comment: Published versio