A generalized multi-period mean-variance portfolio optimization with Markov switching parameters

In this paper, we deal with a generalized multi-period mean-variance portfolio selection problem with market parameters Subject to Markov random regime switchings. Problems of this kind have been recently considered in the literature for control over bankruptcy, for cases in which there are no jumps in market parameters (see [Zhu, S. S., Li, D., & Wang, S. Y. (2004). Risk control over bankruptcy in dynamic portfolio selection: A generalized mean variance formulation. IEEE Transactions on Automatic Control, 49, 447-457]). We present necessary and Sufficient conditions for obtaining an optimal control policy for this Markovian generalized multi-period meal-variance problem, based on a set of interconnected Riccati difference equations, and oil a set of other recursive equations. Some closed formulas are also derived for two special cases, extending some previous results in the literature. We apply the results to a numerical example with real data for Fisk control over bankruptcy Ill a dynamic portfolio selection problem with Markov jumps selection problem. (C) 2008 Elsevier Ltd. All rights reserved.

Evaluation of two round baling systems for harvesting understory biomass

The objective of this study was to evaluate the performance and to estimate costs of two round baling systems for harvesting understory biomass. One system was a cutter-shredderbaler prototype (Bio-baler). The other system required two successive operations. The first operation was cutting and shredding with a Supertrak tractor equipped with a Fecon mulcher head. The second operation was baling with a Claas baler. The machines were evaluated in three different pine stands on the Osceola National Forest in Florida, United States. Data collection included time study, fuel consumption and bale measurements. Material was collected from a sample of bales for heat and moisture content determination. On the most representative site (Site 2), the Bio-baler recovered 8.05 green t ha(-1) while the mulcher and the Claas baler recovered 9.75 green t ha(-1) (43 and 52 percent of original understory biomass, respectively). Productivity was 0.30 ha h(-1) for the Bio-baler and 0.51 ha h(-1) for the Claas baler. Density of the bales was 321 green kg m(-3) for the Bio-baler and 373 green kg m(-3) for the Claas baler. Average net heat content was 6263 MJ bale(-1) for the Bio-baler and 6695 MJ bale(-1) for the Claas baler with biomass containing 38 percent of moisture content on a wet basis. cost per unit area was less with the Bio-baler (US$320.91 ha(-1)) than with the mulcher-baler system (US$336.62-US$596.77 ha(-1)). Published by Elsevier Ltd.

Performance of a multi-level TDR system exposed to tropical field conditions - A time-space comparison with tensiometry

Time-domain reflectometry (TDR) is an important technique to obtain series of soil water content measurements in the field. Diode-segmented probes represent an improvement in TDR applicability, allowing measurements of the soil water content profile with a single probe. In this paper we explore an extensive soil water content dataset obtained by tensiometry and TDR from internal drainage experiments in two consecutive years in a tropical soil in Brazil. Comparisons between the variation patterns of the water content estimated by both methods exhibited evidences of deterioration of the TDR system during this two year period at field conditions. The results showed consistency in the variation pattern for the tensiometry data, whereas TDR estimates were inconsistent, with sensitivity decreasing over time. This suggests that difficulties may arise for the long-term use of this TDR system under tropical field conditions. (c) 2008 Elsevier B.V. All rights reserved.

Mate (Ilex paraguariensis) as a source of water extractable antioxidant for use in chicken meat

Aqueous extract of mate, made from dried leaves of Ilex paraguariensis, St. Hilaire, was shown to be effective during chilled storage for up to 10 days in protecting lipids and vitamin E against oxidation in pre-cooked meat balls made from chicken breast added 0.5% salt and packed in atmospheric air. Extracts made with water, methanol, ethanol or 70% aqueous acetone were evaluated by comparing (1) total phenolic content, (2) radical scavenging capacity, (3) effect on lipid oxidation in a food emulsion model, and in liposomes. Based on the three-step evaluation, aqueous mate extract was preferred for food use. Dried leaves were further compared to dried rosemary leaves in chicken meat balls, and mate (0.05 and 0.10%) found to yield equal or better protection than rosemary at the same concentration against formation of secondary lipid oxidation products.

CO(2) from Alcoholic Fermentation for Continuous Cultivation of Arthrospira (Spirulina) platensis in Tubular Photobioreactor Using Urea as Nitrogen Source

Carbon dioxide released from alcoholic fermentation accounts for 33% of the whole CO(2) involved in the use of ethanol as fuel derived from glucose. As Arthrospira platensis can uptake this greenhouse gas, this study evaluates the use of the CO(2) released from alcoholic fermentation for the production of Arthrospira platensis. For this purpose, this cyanobacterium was cultivated in continuous process using urea as nitrogen source, either using CO(2) from alcoholic fermentation, without any treatment, or using pure CO(2) from cylinder. The experiments were carried out at 120 mu mol photons m(-2) s(-1) in tubular photobioreactor at different dilution rates (0.2 <= D <= 0.8 d(-1)). Using CO(2) from alcoholic fermentation, maximum steady-state cell concentration (2661 +/- 71 mg L(-1)) was achieved at D 0.2 d(-1), whereas higher dilution rate (0.6 d(-1)) was needed to maximize cell productivity (839 mg L(-1) d(-1)). This value was 10% lower than the one obtained with pure CO(2), and there was no significant difference in the biomass protein content. With D 0.8 d(-1), it was possible to obtain 56% +/- 1.5% and 50% +/- 1.2% of protein in the dry biomass, using pure CO(2) and CO(2) from alcoholic fermentation, respectively. These results demonstrate that the use of such cost free CO(2) from alcoholic fermentation as carbon source, associated with low cost nitrogen source, may be a promising way to reduce costs of continuous cultivation of photosynthetic microorganisms, contributing at the same time to mitigate the greenhouse effect. (C) 2011 American Institute of Chemical Engineers Biotechnol. Prog., 27: 650-656, 2011

Evaluation of the composition of continuously-cultivated Arthrospira (Spirulina) platensis using ammonium chloride as nitrogen source

This work is focused on the influence of dilution rate (0.08 <= D <= 0.32 d(1)) on the continuous cultivation and biomass composition of Arthrospira (Spirulina) platensis using three different concentrations of ammonium chloride (c(No) = 1.0, 5.0 and 10 mol m (3)) as nitrogen source. At c(No) = 1.0 and 5.0 mol m (3) the biomass protein content was an increasing function of D, whereas, when using c(No) = 10 mol m (3), the highest protein content (72.5%) was obtained at D = 0.12 d (1). An overall evaluation of the process showed that biomass protein content increased with the rate of nitrogen supply (D c(No)) up to 72.5% at D c(No) = 1.20 mol m (3) d (1). Biomass lipid content was an increasing function of D only when the nitrogen source was the limiting factor for the growth (D c(No) <= 0.32 mol m (-3) d (1)), which occurred solely with c(No), = 1.0 mol m (3). Under such conditions, A. platensis reduced its nitrogen reserve in the form of proteins, while maintaining almost unvaried its lipid content. The latter was affected only when the concentration of nitrogen was extremely low (c(No) = 1.0 mol m (3)). The most abundant fatty acids were the palmitic (45.8 +/- 5.20%) and the gamma-linolenic (20.1 +/- 2.00%) ones. No significant alteration in the profiles either of saturated or unsaturated fatty acids was observed with c(No) <= 5.0 mol m (3), prevailing those with 16 and 18 carbons. (C) 2010 Elsevier Ltd. All rights reserved.

Repeated fed-batch cultivation of Arthrospira (Spirulina) platensis using urea as nitrogen source

Arthospira (Spirulina) platensis (Nordstedt) Gomont was autotrophically cultivated for biomass production in repeated fed-batch process using urea as nitrogen source, with the aim of making large-scale production easier, increasing cell productivity and then reducing the production costs. It was investigated the influence or the ratio of renewed volume to total volume (R), the Urea feeding time (t(f)) and the number of successive repealed fed-batch cycles on the maximum cell concentration (X(m)), cell productivity (P(x)), nitrogen-to-cell conversion yield (Y(x/n)), maximum specific growth rate (mu(m)) and protein content of, dry biomass. The experimental results demonstrated chat R=0.80 and t(f) = 6d were the best cultivation conditions, being able to simultaneously ensure, throughout the three fed-batch cycles, the highest average values of three of the five responses (X(m) = 2101 +/- 113 mg L(-1), P(x) = 219 +/- 13 mg L(-1) d(-1) and Y(x/n) = 10.3 +/- 0.8,g g(-1)). (C) 2008 Elsevier B.V. All rights reserved.

Hand position on the bunch and source-sink ratio influence the banana fruit susceptibility to crown rot disease

The postharvest development of crown rot of bananas depends notably on the fruit susceptibility to this disease at harvest. It has been shown that fruit susceptibility to crown rot is variable and it was suggested that this depends on environmental preharvest factors. However, little is known about the preharvest factors influencing this susceptibility. The aim of this work was to evaluate the extent to which fruit filling characteristics during growth and the fruit development stage influence the banana susceptibility to crown rot. This involved evaluating the influence of (a) the fruit position at different levels of the banana bunch (hands) and (b) changing the source-sink ratio (So-Si ratio), on the fruit susceptibility to crown rot. The fruit susceptibility was determined by measuring the internal necrotic surface (INS) after artificial inoculation of Colletotrichum musae. A linear correlation (r = -0.95) was found between the hand position on the bunch and the INS. The So-Si ratio was found to influence the pomological characteristics of the fruits and their susceptibility to crown rot. Fruits of bunches from which six hands were removed (two hands remaining on the bunch) proved to be significantly less susceptible to crown rot (INS = 138.3 mm 2) than those from bunches with eight hands (INS = 237.9 mm 2). The banana susceptibility to crown rot is thus likely to be influenced by the fruit development stage and filling characteristics. The present results highlight the importance of standardising hand sampling on a bunch when testing fruit susceptibility to crown rot. They also show that hand removal in the field has advantages in the context of integrated pest management, making it possible to reduce fruit susceptibility to crown rot while increasing fruit size.

Multilabeled classification approach to find a plaint source for terpenoids

Recently, we have built a classification model that is capable of assigning a given sesquiterpene lactone (STL) into exactly one tribe of the plant family Asteraceae from which the STL has been isolated. Although many plant species are able to biosynthesize a set of peculiar compounds, the occurrence of the same secondary metabolites in more than one tribe of Asteraceae is frequent. Building on our previous work, in this paper, we explore the possibility of assigning an STL to more than one tribe (class) simultaneously. When an object may belong to more than one class simultaneously, it is called multilabeled. In this work, we present a general overview of the techniques available to examine multilabeled data. The problem of evaluating the performance of a multilabeled classifier is discussed. Two particular multilabeled classification methods-cross-training with support vector machines (ct-SVM) and multilabeled k-nearest neighbors (M-L-kNN)were applied to the classification of the STLs into seven tribes from the plant family Asteraceae. The results are compared to a single-label classification and are analyzed from a chemotaxonomic point of view. The multilabeled approach allowed us to (1) model the reality as closely as possible, (2) improve our understanding of the relationship between the secondary metabolite profiles of different Asteraceae tribes, and (3) significantly decrease the number of plant sources to be considered for finding a certain STL. The presented classification models are useful for the targeted collection of plants with the objective of finding plant sources of natural compounds that are biologically active or possess other specific properties of interest.

Making Fedora easier to implement with Fez: A free open source content model and workflow management front-end to Fedora

The University of Queensland, Australia has developed Fez, a world-leading user-interface and management system for Fedora-based institutional repositories, which bridges the gap between a repository and users. Christiaan Kortekaas, Andrew Bennett and Keith Webster will review this open source software that gives institutions the power to create a comprehensive repository solution without the hassle..

A master equation model for bimolecular reaction via multi-well isomerization intermediates

A reversible linear master equation model is presented for pressure- and temperature-dependent bimolecular reactions proceeding via multiple long-lived intermediates. This kinetic treatment, which applies when the reactions are measured under pseudo-first-order conditions, facilitates accurate and efficient simulation of the time dependence of the populations of reactants, intermediate species and products. Detailed exploratory calculations have been carried out to demonstrate the capabilities of the approach, with applications to the bimolecular association reaction C3H6 + H reversible arrow C3H7 and the bimolecular chemical activation reaction C2H2 +(CH2)-C-1--> C3H3+H. The efficiency of the method can be dramatically enhanced through use of a diffusion approximation to the master equation, and a methodology for exploiting the sparse structure of the resulting rate matrix is established.

Public support for sustainable commercial harvesting of wildlife: An Australian case study

This paper surveys a sample of 204 members of the Australian public to determine their attitude to the sustainable commercial harvesting of wildlife generally, and considers their specific support for the sustainable commercial harvesting of each of 24 Australian native species. The general attitude of the sample to wildlife harvesting is related to their attitude to nature conservation. The relationship between respondents’ support for the sustainable commercial harvesting of each of the species and their degree of endangerment based on IUCN Red List rankings is established and found to be an inverse one. Support for the commercial sustainable use of each of the species is compared with the willingness of respondents to pay for their conservation. Support for sustainable commercial harvesting of species is found to be inversely related to the willingness of respondents to pay is for a particular species’ conservation. In turn, this willingness to pay is found to rise with the degree of endangerment of species. While the likeability of a species has some influence on whether there is support or not for its commercial harvesting, it does not seem to be the predominant influence— the degree of endangerment of a species appears to be the major influence here. Even so, this does not imply majority support for the harvest of all species that are not threatened; rather, majority support for harvest was observed only for some species known to be abundant. None of the species that appear in the Red List have majority support for harvesting. Implications are outlined of the results for the policy of promoting wildlife conservation by means of sustainable use.

Prediction of the chemical composition of lamb carcasses from multi-frequency impedance data

Multi-frequency bioimpedance analysis (MFBIA) was used to determine the impedance, reactance and resistance of 103 lamb carcasses (17.1-34.2 kg) immediately after slaughter and evisceration. Carcasses were halved, frozen and one half subsequently homogenized and analysed for water, crude protein and fat content. Three measures of carcass length were obtained. Diagonal length between the electrodes (right side biceps femoris to left side of neck) explained a greater proportion of the variance in water mass than did estimates of spinal length and was selected for use in the index L-2/Z to predict the mass of chemical components in the carcass. Use of impedance (Z) measured at the characteristic frequency (Z(c)) instead of 50 kHz (Z(50)) did not improve the power of the model to predict the mass of water, protein or fat in the carcass. While L-2/Z(50) explained a significant proportion of variation in the masses of body water (r(2) 0.64), protein (r(2) 0.34) and fat (r(2) 0.35), its inclusion in multi-variate indices offered small or no increases in predictive capacity when hot carcass weight (HCW) and a measure of rib fat-depth (GR) were present in the model. Optimized equations were able to account for 65-90 % of the variance observed in the weight of chemical components in the carcass. It is concluded that single frequency impedance data do not provide better prediction of carcass composition than can be obtained from measures of HCW and GR. Indices of intracellular water mass derived from impedance at zero frequency and the characteristic frequency explained a similar proportion of the variance in carcass protein mass as did the index L-2/Z(50).