1,372 research outputs found
Market trends of seafood products under international constraints: contractualisation, marketing strategies and new behaviours
In the developed countries, especially in the European Union, demand for seafood products has increased very quickly (faster than that of meat products). This growth may be explained by the recurring problems of animal health impacts on other products (bovine spongiform encephalopathy (BSE), avian influenza (bird flu)...) and to the impacts of the environmental problems (dioxins...) which are less prevalent in seafood products. In addition, seafood products profit from an increasingly positive image positioned on the axis of nutrition- health. The enhancement of the markets is influenced more and more by the retailing channel (hyper and supermarkets). Indeed, France profits from being a pioneer in retailing, (more than 70% of the seafood market is through retailers) who can be seen as axis of development with other sectors and in other countries. To satisfy the demand, the national platforms of the retailers rely upon imported products to supplement their supplies from local fishermen and fish farmers. These local actors must adapt to the constraints imposed by the platforms, which constitutes a major innovation in the contractual relationship with the hyper and supermarket stores. The international context weighs heavily in the determination of these constraints. This paper deals with this framework of the new forms of contractualisation between the actors imposed by the evolution of the international context. It also describes the implications in term of setting in market and marketing strategies. Lastly, it takes into account the emergence characteristics of new food buying behaviours.seafood products, contractualisation, price, sale promotions, marketing, behaviours, Marketing,
Evaporation du sol nu en zone semi-aride et en conditions hivernales. Relations avec l'albédo et la température de la surface du sol
L'évaporation d'un sol nu dans le Sud Tunisien au mois de novembre, est mesurée après une pluie, ainsi que son albédo, sa température de surface et celle d'une parcelle maintenue humide par irrigation. Les mesures font apparaître une chute rapide de l'évaporation par rapport à l'évaporation potentielle, malgré l'existence d'une réhumectation nocturne. L'albédo, très sensible d'abord, évolue ensuite lentement et rend mal compte des derniers stades du dessèchement du sol. L'écart entre les températures de surface des deux parcelles suit par contre fidèlement la chute de l'évaporation et peut donc être considéré comme un bon témoin de ce phénomène. (Résumé d'auteur
Decays of Heavy Mesons
We present preliminary results for heavy to light transitions of pseudoscalar
mesons, induced by the vector and tensor operators. This lattice study is
performed in quenched approximation, by using the nonperturbatively improved
Wilson action and operators. We also update the values of the heavy-light meson
decay constants.Comment: LATT99(Heavy Quarks), 3 pages, 2 figure
Stretching from Punch Card/Programming to Business Data Processing to Business Information Systems
The world’s oldest undergraduate degree program in data processing and information systems at Mississippi State University turned fifty years old in 2013. In this paper, we review the pioneering activities of the program’s founder, Charles Moore, and provide insights into his foresight about the potential importance of information systems to business organizations. We explain how the program’s founding marked a shift in the epistemological view of information systems education in the mid-1960s. We show the course offerings of business data processing and information systems and the timeline at MSU over the past five decades. We also share how his efforts are instilled in the continuing development of the business information systems program at Mississippi State University to this day
Comparison of Two Common Maximum Power Point Trackers by Simulating of PV Generators
AbstractPower point tracker algorithms play an important role in the optimization of the power and the efficiency of a photovoltaic generator (PVG).We made the comparison between two algorithms currently implemented for the power optimization of PVG. These algorithms are based on the Perturb Observe and the Conductance-Increment methods allowing the Maximum Power Point Tracking, MPPT, principle. The study leads us to conclude that these algorithms are not well adapted for PVG exposures in very unfavorable but realistic external conditions
Transcriptome analysis of honey bee larvae following neonicotinoid exposure
The current decline of the European Honey Bee (Apis Mellifera) has been linked to the increasing use of neonicotinoid pesticides within agriculture. Whilst the toxicity of these pesticides to Apis has long been established, the possibility of low dosages inducing molecular stress has not yet been fully explored. Of particular interest is the action of these nicotine derivatives on the nicotinic acetylcholine receptor, and its association with the DNA methyltransferase family (Dnmts).
An experimental group of three hives were exposed to sugar water contaminated with a low concentration of imidacloprid (2µg/l). From these hives, 12 third instar larvae were selected. A corresponding number of larvae were also selected from three control hives, for a total of 12 samples. Using quantitative reverse transcription-PCR, known Dnmt transcripts were detected and amplified from these larval samples. Specially designed oligonucleotide primers were used containing gene specific sequences that linked to universal DNA sequences, ensuring that PCR amplification products were of predetermined sizes. Products of this amplification were resolved by capillary electrophoresis and detected by fluorescence spectrophotometry. Simultaneously, the transcriptomes of 3 larval samples each from the control and experimental groups were generated using SOLiD platform sequencing. The statistical package EdgeR was then utilised to identify differential candidates of known honey bee microRNA’s.
Statistical analysis utilising a one-way Analysis of Variance (ANOVA) found no significant differences in the expression levels of known Dnmt transcripts between control and experimental groups. However, comparisons of sequenced control and experimental transcriptomes identified a number of differential microRNA candidates, most notably miR-9/14
The metabolomics of host-parasitoid interactions
This thesis examines the relationship between insect life history and behavioural decisions and underlying cellular biochemistry, with particular focus on bethylid parasitoid wasps in the genus Goniozus. This comprises the first major body of work attempting to draw links between the underlying metabolome of an organism and its behaviour. This thesis further optimised the first known example of a combined LC-MS and NMR metabolomic approach capable of analysing extremely low biomass samples (<1 mg), a vital requirement when studying the behaviour of individual organisms. Part 1 of this thesis details the optimisation and validation of this metabolomic approach, whilst also examining the effects of aging on the metabolome of adult Goniozus wasps. Part 2 applies this approach to examine the effects of diet, host species and host aging on Goniozus wasp behaviour and biochemistry. Comparisons of the metabolomes of starved and honey fed wasps indicate that G. legneri is capable of utilising a carbohydrate rich diet as an energy source. Aged honey fed wasps possessed higher levels of large storage lipids, such as tri- and diacylglycerides, than starved wasps of the same age. Metabolomic analysis also detected a legacy effect on the metabolome of G. legneri associated with differences in the species of host each wasp was reared on. A similar legacy effect was confirmed when examining the metabolomes of wasps reared on artificially aged hosts. Whilst Goniozus wasp oviposition behaviour was altered by the species of host presented, no links between changes in a wasp’s metabolome and its resulting contest behaviour were found. Part 3 of this thesis examines the morphological, behavioural and chemical mimicry of another wasp, the hyperparasitoid Gelis agilis. G. agilis demonstrated an enhanced predation avoidance rate compared with control species, similar to that of the black garden ant Lasius niger. Agitation of G. agilis also resulted in the chemical emission of a known ant alarm pheromone
Growth Route Toward III-V Multispectral Solar Cells on Silicon
To date, high efficiency multijunction solar cells have been developed on Ge
or GaAs substrates for space applications, and terrestrial applications are
hampered by high fabrication costs. In order to reduce this cost, we propose a
breakthrough technique of III-V compound heteroepitaxy on Si substrates without
generation of defects critical to PV applications. With this technique we
expect to achieve perfect integration of heterogeneous Ga1-xInxAs
micro-crystals on Si substrates. In this paper, we show that this is the case
for x=0. GaAs crystals were grown by Epitaxial Lateral Overgrowth on Si (100)
wafers covered with a thin SiO2 nanostructured layer. The cristallographic
structure of these crystals is analysed by MEB and TEM imaging. Micro-Raman and
Micro-Photomuminescence spectra of GaAs crystals grown with different
conditions are compared with those of a reference GaAs wafer in order to have
more insight on eventual local strains and their cristallinity. This work aims
at developping building blocks to further develop a GaAs/Si tandem demonstrator
with a potential conversion efficiency of 29.6% under AM1.5G spectrum without
concentration, as inferred from our realistic modeling. This paper shows that
Epitaxial Lateral Overgrowth has a very interesting potential to develop
multijunction solar cells on silicon approaching the today 30.3% world record
of a GaInP/GaAs tandem cell under the same illumination conditions, but on a
costlier substrate than silicon.Comment: Preprint of the 28th EUPVSEC proceedings, September 2013, Paris,
France. (5 pages
The metabolomics of host-parasitoid interactions
This thesis examines the relationship between insect life history and behavioural decisions and underlying cellular biochemistry, with particular focus on bethylid parasitoid wasps in the genus Goniozus. This comprises the first major body of work attempting to draw links between the underlying metabolome of an organism and its behaviour. This thesis further optimised the first known example of a combined LC-MS and NMR metabolomic approach capable of analysing extremely low biomass samples (<1 mg), a vital requirement when studying the behaviour of individual organisms. Part 1 of this thesis details the optimisation and validation of this metabolomic approach, whilst also examining the effects of aging on the metabolome of adult Goniozus wasps. Part 2 applies this approach to examine the effects of diet, host species and host aging on Goniozus wasp behaviour and biochemistry. Comparisons of the metabolomes of starved and honey fed wasps indicate that G. legneri is capable of utilising a carbohydrate rich diet as an energy source. Aged honey fed wasps possessed higher levels of large storage lipids, such as tri- and diacylglycerides, than starved wasps of the same age. Metabolomic analysis also detected a legacy effect on the metabolome of G. legneri associated with differences in the species of host each wasp was reared on. A similar legacy effect was confirmed when examining the metabolomes of wasps reared on artificially aged hosts. Whilst Goniozus wasp oviposition behaviour was altered by the species of host presented, no links between changes in a wasp’s metabolome and its resulting contest behaviour were found. Part 3 of this thesis examines the morphological, behavioural and chemical mimicry of another wasp, the hyperparasitoid Gelis agilis. G. agilis demonstrated an enhanced predation avoidance rate compared with control species, similar to that of the black garden ant Lasius niger. Agitation of G. agilis also resulted in the chemical emission of a known ant alarm pheromone
Transcriptome analysis of honey bee larvae following neonicotinoid exposure
The current decline of the European Honey Bee (Apis Mellifera) has been linked to the increasing use of neonicotinoid pesticides within agriculture. Whilst the toxicity of these pesticides to Apis has long been established, the possibility of low dosages inducing molecular stress has not yet been fully explored. Of particular interest is the action of these nicotine derivatives on the nicotinic acetylcholine receptor, and its association with the DNA methyltransferase family (Dnmts).
An experimental group of three hives were exposed to sugar water contaminated with a low concentration of imidacloprid (2µg/l). From these hives, 12 third instar larvae were selected. A corresponding number of larvae were also selected from three control hives, for a total of 12 samples. Using quantitative reverse transcription-PCR, known Dnmt transcripts were detected and amplified from these larval samples. Specially designed oligonucleotide primers were used containing gene specific sequences that linked to universal DNA sequences, ensuring that PCR amplification products were of predetermined sizes. Products of this amplification were resolved by capillary electrophoresis and detected by fluorescence spectrophotometry. Simultaneously, the transcriptomes of 3 larval samples each from the control and experimental groups were generated using SOLiD platform sequencing. The statistical package EdgeR was then utilised to identify differential candidates of known honey bee microRNA’s.
Statistical analysis utilising a one-way Analysis of Variance (ANOVA) found no significant differences in the expression levels of known Dnmt transcripts between control and experimental groups. However, comparisons of sequenced control and experimental transcriptomes identified a number of differential microRNA candidates, most notably miR-9/14
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