The Influence of Local Selling Decisions on Organic Farm Incomes

Abstract: This paper examines the factors that influence earned income of organic farmers given their decisions to engage in local selling. The model explicitly accounts for the sorting of producers across different levels of commitment to local sales on the basis of both observable and unobservable heterogeneity. The significant selectivity coefficients confirm that when producers choose to market organic products primarily through local outlets, earnings are overestimated (biased upward) if the selectivity corrections are neglected. Positive selection effects are present for farmers most intensively involved in local sales, contributing to higher earnings on average for these producers.organic marketing, local food, selectivity bias, ordered probit, Agribusiness, Marketing, L25, L81, J24,

DEMAND AND QUALITY UNCERTAINTY IN PECAN PURCHASING DECISIONS

Fixed search costs associated with locating and purchasing pecans invalidate the Tobit model. Factors such as perceived quality, ease of purchase, and familiarity with marketing outlets influence the fixed costs of pecan purchases. These factors have differing impacts on the probability of purchasing and the amount purchased based on the Heckman model. Failure to apply self-selectivity corrections produces misleading assessments of key variables influencing pecan purchases. (Missing tables 1,2,3)pecan demand, consumer quality expectations, Heckman model, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

Feeding selectivity of brown trout (Salmo trutta) in Loch Ness, Scotland

The aim of this study was to compare statistically the zooplankton assemblage ingested by brown trout (Salmo trutta) in Loch Ness with that of the zooplankton in the water column. This would allow the examination of the apparent paradox that very few copepods appear to be consumed by trout at a time of year when they are numerous and readily available as food. The investigation was limited to the crustacean zooplankters, since the Rotifera are generally so small that they are only of interest to fish in the first few days of life. 25 trout were obtained from anglers, and the stomach contents of non-"ferox" animals analysed. Samples of pelagic zooplankton were obtained approximately monthly from 30-m vertical net-hauls (mesh size 100 km). It is concluded that the variation in dietary composition with trout wet weight indicates an ontogenetic habitat shift producing spatial separation of young and older individuals

On the methodology of feeding ecology in fish

Feeding ecology explains predator’s preference to some preys over others in their habitat and their competitions thereof. The subject, as a functional and applied biology, is highly neglected, and in case of fish, a uniform and consistent methodology is absent. The currently practiced methods are largely centred on mathematical indices and highly erroneous because of non-uniform outcomes. Therefore, it requires a relook into the subject to elucidate functional contributions and to make it more comparable and comprehensive science. In this article, approachable methodological strategies have been forwarded in three hierarchical steps, namely, food occurrence, feeding biology and interpretative ecology. All these steps involve wide ranges of techniques, within the scope of ecology but not limited to, and traverse from narrative to functional evolutionary ecology. The first step is an assumption-observation practice to assess food of fish, followed by feeding biology that links morphological, histological, cytological, bacteriological or enzymological correlations to preferred food in the environment. Interpretative ecology is the higher level of analysis in which the outcomes are tested and discussed against evolutionary theories. A description of possible pedagogics on the methods of feeding ecological studies has also been forwarded

Bioavailability of pesticides in freshwater sediments

In ecological risk assessment standardized sediment toxicity tests are used to predict the hazard of chemicals for sediment-living organisms. Feeding is a prerequisite in these long-term tests to avoid starvation of test organisms. Therefore, added food particles may act as vectors for the test compound. The importance of food particles as vectors, however, is dependent on several factors, for example, sorption and major uptake routes. In this thesis, laboratory experiments on the importance of pesticide sorption and uptake routes for the bioavailability to the midge Chironomus riparius in sediment toxicity test setups were performed. A feeding selectivity study showed that larvae almost exclusively fed on added food particles, and highly neglected sediment particles. Additionally, experiments on the sorption of the insecticide lindane, showed that food and peat particles (used in artificial sediment) efficiently sorbed lindane (>95% after 48 h). The binding strength of lindane was weak, facilitating particulate uptake. However, the uptake from dissolved lindane was higher than the uptake from particles. From this we concluded that toxicity may be underestimated in spiked-sediment scenarios, where hydrophobic pesticides sorb to the sediment and larvae to a large extent feed on uncontaminated food particles. Conversely, in a spiked-water scenario, the food particles may act as vector, resulting in a facilitated particulate uptake, in addition to the uptake from water. Sediment organic matter affects sorption, and thus bioavailability of pesticides. Pyrethroid toxicity was much higher in artificial sediment than in a natural sediment, indicating the simplicity and shortcomings of using artificial sediments. Interestingly, the sediment quality highly affected bioavailability in spiked-water. For example, C. riparus larvae in sediments with low organic matter content and exposed to spiked-water pyrethroids, showed lower survival, slower development, and increased adult size, than those in sediments with higher organic matter. The pyrethroid deltamethrin, showed an LC50-value (28 d) for C. riparius larvae in artificial sediment of 16 pg/L and 11 µg/kg for water- and sediment exposures, respectively, i.e. toxic effects occurred at concentrations lower than the detection limits for high-tech analytical methods. This thesis contributes to a wider understanding of processes affecting bioavailability in freshwater sediments, and in particular in standardized sediments used in toxicity testing. The understanding of test compound sorption and bioavailability is crucial for sound interpretations of toxicity tests and for the general credibility of such tests

Screening and Evaluation of Essential Oils from Mediterranean Aromatic Plants against the Mushroom Cobweb Disease, Cladobotryum mycophilum

The main aim of this study was to evaluate the use of essential oils (EOs) as an alternative to synthetic fungicides used in the control of cobweb disease of button mushroom (Agaricus bisporus) caused by Cladobotryum mycophilum. The EOs used were obtained by hydrodistillation from five Mediterranean aromatic species (Lavandula × intermedia, Salvia lavandulifolia, Satureja montana, Thymus mastichina, and Thymus vulgaris), analyzed by gas chromatography, and tested in vitro for their antifungal activity against C. mycophilum. In vitro bioassays showed that the EOs obtained from T. vulgaris and S. montana (ED50 = 35.5 and 42.8 mg L−1, respectively) were the most effective EOs for inhibiting the mycelial growth of C. mycophilum, and were also the most selective EOs between C. mycophilum and A. bisporus. The in vivo efficacy of T. vulgaris and S. montana EOs at two different concentrations (0.5 and 1%) were evaluated in two mushroom growing trials with C. mycophilum inoculation. The treatments involving T. vulgaris and S. montana EOs at the higher dose (1% concentration) were as effective as fungicide treatment. The effect of these EOs on mushroom productivity was tested in a mushroom cropping trial without inoculation. They had a strong fungitoxic effect at the first flush. However, a compensatory effect was observed by the end of the crop cycle and no differences were observed in biological efficiency between treatments. The main compounds found were carvacrol and p-cymene for S. montana, and p-cymene and thymol for T. vulgaris. These results suggest that T. vulgaris and S. montana EOs may be useful products to manage cobweb disease if used as part of an integrated pest management (IPM) program

Gas separation membrane

A method of fabricating a gas separation membrane includes providing a coextruded multilayer film that includes a first polymer layer formed of a first polymer material and a second polymer layer formed of a second polymer material, the first polymer material having a first gas permeability. The coextruded multilayer film is axially oriented such that the second polymer layer has a second gas permeability that is greater than the first gas permeability.Board of Regents, University of Texas Syste

Common carp (Cyprinus carpio L.) alters its feeding niche in response to changing food resources: direct observations in simulated ponds

We used customized fish tanks as model fish ponds to observe grazing, swimming, and conspecific social behavior of common carp (Cyprinus carpio) under variable food-resource conditions to assess alterations in feeding niche. Different food and feeding situations were created by using only pond water or pond water plus pond bottom sediment or pond water plus pond bottom sediment and artificial feeding. All tanks were fertilized twice, prior to stocking and 2 weeks later after starting the experiment to stimulate natural food production. Common carp preferred artificial feed over benthic macroinvertebrates, followed by zooplankton. Common carp did not prefer any group of phytoplankton in any treatment. Common carp was mainly benthic in habitat choice, feeding on benthic macroinvertebrates when only plankton and benthic macroinvertebrates were available in the system. In the absence of benthic macroinvertebrates, their feeding niche shifted from near the bottom of the tanks to the water column where they spent 85% of the total time and fed principally on zooplankton. Common carp readily switched to artificial feed when available, which led to better growth. Common carp preferred to graze individually. Behavioral observations of common carp in tanks yielded new information that assists our understanding of their ecological niche. This knowledge could be potentially used to further the development of common carp aquaculture