Utilisation of plant food waste

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Complex eigenvalues and trend-reverting fluctuations

Autoregressions of quarterly or annual aggregate time series provide evidence of trend-reverting output growth and of short-term dynamic adjustment that appears to be governed by complex eigenvalues. This finding is at odds with the predictions of reasonably parameterized, convex one-sector growth models, most of which have positive real characteristic roots. We study a class of one-sector economies, overlapping generations with finite life spans of L greater than or equal to 3, in which aggregate saving depends nontrivially on the distribution of wealth among cohorts. If consumption goods are weak gross substitutes near the steady state price vector, we prove that the unique equilibrium of a life cycle exchange economy converges to the unique steady state via damped oscillations. We also conjecture that this form of trend reversion extends to production economies with a relatively flat factor-price frontier, and we test this conjecture in several plausible parameterizations of 55-period life cycle economies.Time-series analysis ; Econometric models ; Regression analysis

A Hydrodynamics Perspective for the 2004 Megatsunami

The megatsunami of 26 December 2004 was the first tsunami with transoceanic impact since the 1960 Great Chilean and 1964 Great Alaskan tsunamis. Because of the distribution of deaths among a large portion of the nations of the world, the 2004 Boxing Day tsunami is the first universal natural disaster of modern times. For the purpose of adequate mitigation of future tsunamis, it is important to understand which factors control most critically the final characteristics of the flooding, namely runup and inundation. Their successful modeling requires not only a credible database of inundation parameters, against which models can be tested through numerical simulation of the generation, propagation to the local shores, and final interaction of the tsunami with the target beaches, but also in situ observations that help identify unusual impact and previously unrecognized or controversial flow patterns. Here, I comment on the hydrodynamic lessons -mostly relearned- and describe remaining challenges

The influence of free-stream turbulence on separation of turbulent boundary layers in incompressible, two-dimensional flow

Experiments were conducted to determine if free-stream turbulence scale affects separation of turbulent boundary layers. In consideration of possible interrelation between scale and intensity of turbulence, the latter characteristic also was varied and its role was evaluated. Flow over a 2-dimensional airfoil in a subsonic wind tunnel was studied with the aid of hot-wire anemometry, liquid-film flow visualization, a Preston tube, and static pressure measurements. Profiles of velocity, relative turbulence intensity, and integral scale in the boundary layer were measured. Detachment boundary was determined for various angles of attack and free-stream turbulence. The free-stream turbulence intensity and scale were found to spread into the entire turbulent boundary layer, but the effect decreased as the airfoil surface was approached. When the changes in stream turbulence were such that the boundary layer velocity profiles were unchanged, detachment location was not significantly affected by the variations of intensity and scale. Pressure distribution remained the key factor in determining detachment location

Lasing in metamaterial nanostructures

A self-consistent computational scheme is presented for one dimensional (1D) and two dimensional (2D) metamaterial systems with gain incorporated into the nanostructures. The gain is described by a generic four-level system. The loss compensation and the lasing behavior of the metamaterial system with gain are studied. A critical pumping rate exists for compensating the losses of the metamaterial. There exists a wide range of input signals where the composite system behaves linearly. Nonlinearities arise for stronger signals due to gain depletion. The retrieved effective parameters are presented for one layer of gain embedded in two layers of Lorentz dielectric rods and split ring resonators with two different gain inclusions: (1) gain is embedded in the gaps only and (2) gain is surrounding the SRR. When the pumping rate increases, there is a critical pumping rate that the metamaterial system starts lasing.Comment: 18 pages, 19 figures, submitted to Journal of Optics A: Pure and Applied Optic

Variabilidad genética para la producción de toxina en poblaciones de Microcystis aeruginosa en dos embalses de abastecimiento de Andalucía

Las proliferaciones de cianobacterias tóxicas ocurren a menudo en aguas continentales. Entre todas las especies de cianobacterias, la especie productora de microcistinas (hepatotoxinas) Microcystis aeruginosa, es la principal fuente de problemas tanto para animales como para el hombre. Las proliferaciones de Microcystis se caracterizan por presentar una fuerte heterogeneidad en su producción de toxinas tanto espacial como temporalmente. Habitualmente se atribuye a factores ambientales esta heterogeneidad. Sin embargo, las diferencias genéticas podrían jugar un papel destacado. En este trabajo hemos detectado y cuantificado variabilidad genética para la producción de toxina tanto dentro de una proliferación como cuando se encuentran a baja concentración en dos poblaciones de M. aeruginosa. Para ello se aislaron y cultivaron 17 cepas de M. aeruginosa de dos embalses de Andalucía, y se mantuvieron en idénticas condiciones ambientales. La producción de microcistinas se midió utilizando un test ELISA en cultivos completamente aclimatados. Se detectó variabilidad estadísticamente significativa entre las distintas cepas. En contraste con el punto de vista clásico, la mayoría de esta variabilidad para producción de toxinas es debida a diferencias genéticas entre especies. Este hecho introduce una fuente de incertidumbre en los sistemas de alerta temprana de embalses de abastecimiento basados generalmente en recuentos de abundancia celularToxic cyanobacteria blooms often occur worldwide in freshwater environments. From all cyanobacteria toxic species, Microcystis aeruginosa, hepatotoxin (microcystin) producing, is known to be the main source of noxious outbreaks to humans and animals. These outbreaks are characterized by the occurrence of Microcystis blooms, which show a high degree of heterogeneity in toxin production in both spatial and temporal scales. Usually, this heterogeneity is explained by environmental factors. However, genetic differences can play an important role. In this work, genetic variability for toxin production was detected within and among natural populations of M. aeruginosa. Seventeen clonal cultures of M. aeruginosa, isolated from two water supply reservoirs of Andalusia (S-Spain) were grown under the same environmental conditions. Toxin quota was measured in fully acclimated balanced growth cultures using a commercial ELISA test kit. Statistically significant variability for the production of microcystin was found among the different strains. Most of intra-bloom and inter-bloom variability in toxin production is due to genetic components in contrast with classical environmental point of view. This fact introduces an important source of uncertainty in early-warning systems of water supply management based on cell abundance

Sweet cherry:composition, postharvest preservation, processing and trends for its future use

Background Sweet cherries (Prunus avium L.) are a nutritious fruit which are rich in polyphenols and have high antioxidant potential. Most sweet cherries are consumed fresh and a small proportion of the total sweet cherries production is value added to make processed food products. Sweet cherries are highly perishable fruit with a short harvest season, therefore extensive preservation and processing methods have been developed for the extension of their shelf-life and distribution of their products. Scope and Approach In this review, the main physicochemical properties of sweet cherries, as well as bioactive components and their determination methods are described. The study emphasises the recent progress of postharvest technology, such as controlled/modified atmosphere storage, edible coatings, irradiation, and biological control agents, to maintain sweet cherries for the fresh market. Valorisations of second-grade sweet cherries, as well as trends for the diversification of cherry products for future studies are also discussed. Key Findings and Conclusions Sweet cherry fruit have a short harvest period and marketing window. The major loss in quality after harvest include moisture loss, softening, decay and stem browning. Without compromising their eating quality, the extension in fruit quality and shelf-life for sweet cherries is feasible by means of combination of good handling practice and applications of appropriate postharvest technology. With the drive of health-food sector, the potential of using second class cherries including cherry stems as a source of bioactive compound extraction is high, as cherry fruit is well-known for being rich in health-promoting components

Effect of biocomposite edible coatings based on pea starch and guar gum on nutritional quality of ‘Valencia’ orange during storage

Application of environmentally friendly components is an approach for substitution of synthetic substances in commercial waxes applied to citrus. In this study, the effect of biocomposite edible coatings based on pea starch and guar gum (PSGG) on total vitamin C, phenolic, flavonoid, anthocyanins, and carotenoid content, and antioxidant capacity of ‘Valencia’ orange stored at 5 °C and 20 °C for four weeks were evaluated. The fruits were coated by a single layer PSGG coating, blended composite PSGG coating containing shellac (Sh) and oleic acid as hydrophobic compounds (PSGG-Sh), and a layer-by-layer (LBL) coating (PSGG as an internal layer and Sh as an external layer). The results showed no significant differences in changes of bioactive compounds between coating treatments after first week storage at both temperatures. The PSGG coatings incorporated with hydrophobic compounds (PSGG-Sh) better preserved the nutritional value and the antioxidant potential of oranges during storage compared with other treatments. The single layer PSGG coating was almost similar to bilayer coating in preserving nutritional value of fruit during storage and less effective than the blended composite PSGG-Sh coating

Characterization of pea starch-guar gum biocomposite edible films enriched by natural antimicrobial agents for active food packaging

Antimicrobial activity of epigallocatechin-3-gallate (EGCG) and two native Australian plants blueberry ash (BBA) fruit and macadamia (MAC) skin extracts against nine pathogenic and spoilage bacteria and seven strains of fungi, using an agar well diffusion assay were investigated. The minimum inhibitory concentrations (MIC) of these compounds were calculated using 96-well microtiter plates method. Finally, active antimicrobial packaging films were prepared by incorporation of EGCG, BBA and MAC extracts at 1-, 2-, 3-, and 4-fold of their correspondence MIC values into edible films based on pea starch and guar gum (PSGG). The antimicrobial activity of films was investigated against target microorganisms by agar disc diffusion technique and quantified using the viable cell count assay. Among the test microorganisms, Salmonella typhimurium and Rhizopus sp. were the most resistance to active films. Films containing EGCG showed the highest activity against all test strains. As the concentration of compounds increased higher than 2 × MIC, the mechanical characteristics of the films were affected considerably. The results indicated that EGCG-PSGG, BBA-PSGG and MAC-PSGG films can be used as active food packaging systems for preserving food safety and prolonging the shelf-life of the packaged food