520 research outputs found
Estimation of the nitrogen releasing in rainbow trout (Oncorhynchus mykiss) farming: proposal of a dynamic model
In recent years,many countries have tried to decrease the nitrogen (N) excretion from animal production for its potential damage to the environment. Fish farming is an important N letting-off sector and should reduce its nitrogen (N) loads while maintaining optimal production. In fish farming production, N waste consists of excretory products and N-containing in faecal products. Research has been done focusing on the water output quality and total ammonia nitrogen (TAN) (Cheng et al. 2003). Several models have been developed to study the N output from fish farming (Frier et al., 1995; Doglioli et al., 2004)
Use of rice protein concentrate in rainbow trout feeding: preliminary results
During the past decades, the fishery industry has excessively used the world fish captures to produce fishmeal and fish oil in order to prepare feed for aquaculture diets. This has led to a drastic reduction of several fish populations (Hardy, 1999; FAO, 1999). At present 70% of the oil and 34% of fishmeal obtained from captures are used for aquaculture industry and, if the aquaculture production will continue to increase as predicted, in a short time it will absorb the entire world oil and fish meal production. Moreover, since fish meal still constitutes an important part of the feed formula for cultivated fish and since a further increase of fish meal availability will not be possible (Hardy, 2001), its price is expected to continue to increase (Tacon, 1998)
Geometric Unification of Higgs Bundle Vacua
Higgs bundles are a central tool used to study a range of intersecting brane
systems in string compactifications. Solutions to the internal gauge theory
equations of motion for the corresponding worldvolume theories of branes give
rise to different low energy effective field theories. This has been heavily
used in the study of M-theory on local spaces and F-theory on local
elliptically fibered Calabi-Yau fourfolds. In this paper we show that the 3D
effective field theory defined by M-theory on a local
space unifies the Higgs bundle data associated with 4D M- and F-theory vacua. This 3D system appears as an interface with finite
thickness between different 4D vacua. We develop the general formalism of
M-theory on such local spaces, and build explicit interpolating
solutions. This provides a complementary local gauge theory analysis of a
recently proposed approach to constructing spaces from generalized
connected sums.Comment: v2: 65 pages, 5 figures, typos corrected, reference and
clarifications adde
Development of a Compton camera for medical applications based on silicon strip and scintillation detectors
International audienceA Compton camera is being developed for the purpose of ion-range monitoring during hadrontherapy via the detection of prompt-gamma rays. The system consists of a scintillating fiber beam tagging hodoscope, a stack of double sided silicon strip detectors (90 Ă‚ 90 Ă‚ 2 mm 3 , 2 Ă‚ 64 strips) as scatter detectors, as well as bismuth germanate (BGO) scintillation detectors (38 Ă‚ 35 Ă‚ 30 mm 3 , 100 blocks) as absorbers. The individual components will be described, together with the status of their characterization
Stakeholders’ Perspective on Groundwater Management in Four Water-Stressed Mediterranean Areas: Priorities and Challenges
Recent studies highlight the fragility of the Mediterranean basin against climate stresses and the difficulties of managing the sustainable development of groundwater resources. In this work, the main issues related to groundwater management have been identified from the stake-holder’s perspective in the following four representative water-stressed Mediterranean areas: the coastal aquifer of Comacchio (Italy), the Alto GuadalentĂn aquifer (Spain), the alluvial aquifer of the Gediz River basin (Turkey), and the Azraq aquifer (Azraq Wetland Reserve, Jordan). This has been achieved by designing a methodology to involve and engage a representative set of stakeholders, including a questionnaire to learn their point of view concerning the current management of aquifer systems and their experience with the already available tools for groundwater resource manage-ment, such as monitoring networks and numerical models. The outcome of the survey has allowed us to identify both particular and common challenges among the four study sites and among the various groups of stakeholders. This information provides valuable insights to improve the transfer of scientific knowledge from the research centers to the authorities managing the groundwater resources and it will help to plan more effective research activities on aquifer management. The proposed methodology could be applied in other aquifers facing similar problems
Performance of the first prototype of the CALICE scintillator strip electromagnetic calorimeter
A first prototype of a scintillator strip-based electromagnetic calorimeter
was built, consisting of 26 layers of tungsten absorber plates interleaved with
planes of 45x10x3 mm3 plastic scintillator strips. Data were collected using a
positron test beam at DESY with momenta between 1 and 6 GeV/c. The prototype's
performance is presented in terms of the linearity and resolution of the energy
measurement. These results represent an important milestone in the development
of highly granular calorimeters using scintillator strip technology. This
technology is being developed for a future linear collider experiment, aiming
at the precise measurement of jet energies using particle flow techniques
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