1,355,700 research outputs found
What is important in preweaning mortality?
No full textData of 60 litters was analysed with multivariable regression models to find out risk factors for low piglet production and mortality. Litter size alone explained 80% of the variation of the number of weaned piglets, when intrapartal hypoxia, trauma and hypoglycaemia had been accounted for. Large litter size caused a higher risk of mortality because of lower birth weight of piglets in large than in small litters and because of the greater variation of weights. High mortality rate did not decrease mean weight gain of survived piglets within a litter when controlled for litter size.vo
Labelling of video images : the first step to develop an automatic monitoring tool of pig aggression
No full textAggressive behaviour in pigs is a serious issue in pig farming since it poses enormous welfare and economic problems in livestock management. Mixing animals usually results in aggression among the group members because the animals have to establish a social hierarchy. At times, this aggressive behaviour can become so intense that animals seriously injure themselves or their pen mates. To immediately identify aggression is therefore extremely important for the farmer in order to limit the economical losses and to increase the welfare of the animals. By using video analysis, it is possible to develop an automatic monitoring technology that is able to detect aggression in pigs. Applying a non-invasive technology such as cameras is a very powerful approach since it does not intrude into the animals' hierarchy and is at the same time highly cost efficient. To develop such a product, it is first required that ethologists observe video images and label the behaviour of the animals in order to define the Golden Standard. This step is very crucial, but time-consuming since it demands hours and hours of observation. This paper describes a tool for helping experts in the observation and manual labelling of specific behaviours, for example aggression
Effects of grazing on the performance and behaviour of beef bulls
No full textWe compared performance and behaviour of finishing Hereford bulls raised at pasture and in an uninsulated barn. Grazing led to leaner carcasses and improved the content of healthy fatty acids (e.g. CLA) in the meat, making the meat more compatible with consumer requirements. Differences in the time-budgets between the housing environments resulted mostly from the different feeding regimes and different space allowances. Stereotyped tongue-rolling was absent and there were no differences between the environments in time spent butting. This indicates that both housing environments were satisfactory in regard to the bulls' welfare. However, more synchronised behaviour in the pasture bulls indicates better opportunities for species-typical social behaviour at pasture.vo
Combined effects of thermal-diffusion and thermal radiation on transient MHD natural convection flow in a vertical channel
No full textPapers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.This study investigates the transient MHD natural convection flow of viscous incompressible electrically
conducting fluid in a vertical channel formed by two infinite
vertical parallel plates in the presence of thermal-diffusion
and thermal radiation. Analytical solutions for energy and momentum equation are derived using perturbation method for steady state operating condition for small value of
radiation parameter. The time dependent energy and momentum equations under relevant initial and boundary conditions are solved using implicit finite difference
method. The effects of the various involved parameters on
the skin friction and Nusselt number at the channel surfaces are discussed. A series of numerical experiments shows that the time required to reach steady state velocity, temperature is directly proportional to the Prandtl
number of the working fluid for fixed values of other controlling parameters.One of the authors Isah Bala Yabo is thankful to Usmanu Danfodiyo University, Sokoto for financial support.am201
Studies of the Alkaline Degradation of Cellulose and the Isolation of Isosaccharinic Acids
No full textCellulosic materials are expected to form a significant proportion of the waste proposed for disposal in underground repositories being designed for the storage of radioactive waste. Under the alkaline conditions of these facilities, cellulose degrades by a so called „peeling‟ reaction resulting in the production of a complex mixture of products (CDPs), the major components being α- and β isosaccharinic acid (α and β-ISA). A significant amount of research has been performed on ISA as part of the safety assessment for the development of these underground repositories due to the ability of ISA to complex with, and increase the solubility of radioactive isotopes. Until now, the vast majority of this research has involved the readily-available α-ISA, only a limited number of studies have involved β-ISA because no simple procedure is available for its isolation. Therefore, in this project, a method for the synthesis and isolation of β-ISA was developed.
Cellulose degradation experiments which were performed to maximise solution concentrations of β-ISA are described in chapter 3. Microcrystalline cellulose was degraded under anaerobic conditions at either RT, 50 °C or 90 °C and comparisons were made between the use of NaOH and Ca(OH)2 as the base catalyst. As expected, the major products of all degradation reactions were α- and β-ISA, in addition, small amounts of free metasaccharinic acid (MSA) was detected in the Ca(OH)2 reactions. The largest solution concentrations of β-ISA were produced when cellulose was degraded at 90 °C using NaOH; after 24 hrs of reaction, solution concentrations of 12.7 g L-1 were achieved, whereas, in the equivalent Ca(OH)2 reaction, after 4 days a maximum concentration of only 5.1 g L-1was produced. For this reason, cellulose was degraded at 90 °C using NaOH to produce degradation solutions to be used in procedures to isolate β ISA. An additional finding was that significant amounts of ISA were being removed from degradation solutions due to absorption on to unreacted cellulose fibres; in the NaOH reaction, absorption was occurring rapidly and the percentage of ISA in both the solution and solid phases were very similar. In the Ca(OH)2 reaction, the absorption was a slow process and the percentage of ISA on the solid phase (61 %) was lower than the percentage of ISA in the solution phase (84 %) suggesting that solid Ca(OH)2 was affecting both the rate at which absorption was occurring and the composition of the absorbed species; this was possibly due to solid Ca(OH)2 physically obstructing the access of ISA to the cellulose fibres and also catalysing the oxidation of some of the ISA into smaller fragmentation products.
Methods which were developed to isolate β-ISA are described in chapter 4. Isolation of β-ISA was initially achieved by eluting crude cellulose degradation solutions directly through a column of anion exchange resin. Using an automated system, a large throughput of material was possible resulting in the accumulation of relatively large amounts of β-ISA; after repeating the column 17 times, 1 g of pure β-ISA was isolated. However, using this method, the crude solutions severely fouled the anion exchange resin, concluding that anion exchange was more suited to small scale isolations of β-ISA. A final isolation procedure was developed which involved the elution of mixtures of benzoylated CDPs through normal phase silica columns. It was determined that prior to elution, coloured impurities could be efficiently removed by passing the derivatised mixture through a wide bed of silica. Slow elution of the resulting clean syrup through a large silica column allowed up to 7 g of tribenzoylated β-ISAL to be isolated and following de-benzoylation procedures, 2.6 g of β-ISA was isolated from a single column. The large protecting groups also allowed single crystals of both α- and β-tribenzoate to be produced and the resulting X-ray structures confirmed the absolute configuration of tribenzoylated β-ISAL as being 2R, 4S. Additional NMR analysis of collected fractions allowed several other polyhydroxylated compounds to be identified, also present as their perbenzoylated esters, these being: 3,4-dihydroxybutanoic acid, 2,5-dihydroxypentanoic acid, 2,3-dideoxypentanoic acid and 2,4,5-trihydroxypentanoic acid.
The isolation of large amounts of β-ISA allowed several solution phase physical properties of β ISA to be measured and these are reported in chapter 5, including the aqueous pKa (3.61) which was determined using NMR methods. The rate constants for the inter-conversion between ISAH and ISAL were also studied for both α- and β-ISA. In acidic environments, ISAH undergoes an acid catalysed lactonisation to generate isosaccharino-1,4-lactone (ISAL), conversely in basic environments, ISAL undergoes a base catalysed ring-opening to produce ISAH. Using pH-stat autotitration, the second-order rate constants for the lactone hydrolysis reaction were determined, to which values of 25.3 M-1 s-1 for β-ISAL and 97.0 M-1 s-1 for α-ISAL were observed. The acid catalysed lactonisation of ISAH was studied using 1H NMR spectroscopy; the second-order rate constant for the lactonisation of β-ISAH (3.10 x 10-3 M-1 s-1) was larger than the second order rate constant for the lactonisation of α-ISAH (7.04 x 10-4 M-1 s-1)
Performance and behaviour of dairy bulls raised at pasture and in an uninsulated barn
No full textWe compared performance, fatty acid profile of the meat, and behaviour of finishing dairy bulls raised at pasture and in an uninsulated barn. Grazing had no significant effect on the live weight gain, carcass conformation score or carcass fat score of the bulls. However, grazing improved polyunsaturated and saturated fatty acid ratio of the meat. Differences in the distribution of behaviours between the housing environments resulted mostly from the different feeding regimes and different space allowances. Stereotyped tongue-rolling was almost absent in both environment and there were no differences between the environments in time spent butting. This indicates that both housing environments were satisfactory in regard to the bulls' welfare.vo
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ab initio modeling and experimental investigation of Fe2 P by DFT and spin spectroscopies
No full textFe2P alloys have been identified as promising candidates for magnetic refrigeration at room-temperature and for custom magnetostatic applications. The intent of this study is to accurately characterize the magnetic ground state of the parent compound, Fe2P, with two spectroscopic techniques, μSR and NMR, in order to provide solid bases for further experimental analysis of Fe2P-type transition metal based alloys. We perform zero applied field measurements using both techniques below the ferromagnetic transition TC=220 K. The experimental results are reproduced and interpreted using first principles simulations, validating this approach for quantitative estimates in alloys of interest for technological applications.</p
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