932 research outputs found
The Ideal Intersection Property for Groupoid Graded Rings
We show that if a groupoid graded ring has a certain nonzero ideal property,
then the commutant of the center of the principal component of the ring has the
ideal intersection property, that is it intersects nontrivially every nonzero
ideal of the ring. Furthermore, we show that for skew groupoid algebras with
commutative principal component, the principal component is maximal commutative
if and only if it has the ideal intersection property
Two-degree-of-freedom controller design for an ill-conditioned distillation process using µ-synthesis
The structured singular value framework is applied to a distillation benchmark problem formulated for the 1991 IEEE Conference on decision and control (CDC). A two degree of freedom controller, which satisfies all control objectives of the CDC problem, is designed using /spl mu/-synthesis. The design methodology is presented and special attention is paid to the approximation of given control objectives into frequency domain weights
Pre-slaughter handling of reindeer bulls {Rangifer tarandus tarandus L.) — effects on technological and sensory meat quality, blood metabolites and muscular and abomasal lesions
Forty-one reindeer bulls (age 1 1/2 years) were subjected to different pre-slaughter treatments: herding for a short distance to a grazing corral, selection by use of a lasso, lorry transport and helicopter herding for 1, 2 and 3 days respectively. As control, 9 reindeer were shot without previous handling (in the mountains). The results indicated the traditional selection technique of using a lasso to be the most stressful and glycogen-depleting handling procedure so far studied. In the lasso-selected reindeer the lowest glycogen values and the highest ultimate pH values in the meat were measured. The values of the measured parameters indicating stress (aspartate aminotransferase (ASAT), urea, Cortisol and abomasal lesions) were also highest in these reindeer. By contrast, the modern method of herding by helicopter was not found to be detrimental to glycogen content, ultimate pH, the measured blood metabolites, or the frequency of abomasal lesions. In all treatment groups degenerative lesions were observed in the skeletal muscles. No relarionship between technological and sensory meat quality characteristics and skeletal muscle lesions in reindeer could, however, be found in this study. The study confirmed an earlier finding that a 'stress-flavour' could develop in reindeer meat after intensive pre-slaughter handling of the animals. Further study of when and how such "stress-flavour" develops ought to be undertaken
A field study of management stress in reindeer (Rangifer tarandus L)
The impact of stress was studied in semidomesticated reindeer subjected to various herding and handling methods. In herded and handled animals, stress lesions were found, such as abomasal haemorrhage, muscular and myocardial degeneration and marked changes in blood constituents. The degree of change was dependent of the magnitude of stress the animal had been exposed to. Manual handling and restraint was found to be one of the major stress factors. There were evident indications of a cumulative effect of repeated stress events. The use of motor vehicles (helicopter and snow-scooter), for herding and transporting the animals, was found to be an important stress factor. It is concluded that various herding and handling methods studied in the present investigation led to varying degrees of deleterious effects on the health of the animals and a poorer meatquality from slaughtered animals. Hence herding should be undertaken as carefully as possible, the time taken for manual handling should be minimized, and the corrals be so constructed as to cause a minimum of disturbance, capture and restraint. Transportation should be undertaken very cautiously with as little manual handling as possible during loading and unloading. To obtain a good meat quality, animals to be slaughtered should be subjected to a minimum of handling, i.e. slaughter should take place as quickly as possible. Transportation of live animals to slaughterhouses and the keeping of animals in corrals, pens or crates whilst awaiting slaughter will result in a lowered meat quality and should therefore be avoided.En fåltstudie av stress hos ren i samband med olika hanteringsformer.Abstract in Swedish / Sammanfatning: Betydelsen av stress hos ren studerades i hjordar i vilka olika typer av samlings- och hanteringsmetoder anvandes. I samtliga hjordar som utsatts for olika former av drivning forelag hos slaktdjur skador betingade av stress i form av magblodningar, muskelsonderfall och forandringar i blodbilden. De funna skadorna och forandringarna var beroende av den grad av stress som djuren utsatts for. Manuell hantering och inskrankning av djurens rorelsefrihet befanns vara en av de huvudsakliga stressfaktorerna. Det forelag åvenledes en stark indikation på en kumulativ effekt av upprepad stress. Anvandning av motorfordon (helikopter, snoskoter) vid drivning samt vågtransport av levande djur befanns vara betydande stressfaktorer. Det kan fastslås att de olika hanteringsformerna inneburit olika grader av stress. Graden av stresspåverkan innebår olika grader av negativa effekter dels allmånt for djurens hålsotillstånd dels for en forsåmrad kottkvalitet. Sålunda bor drivningar foretagas så forsiktigt som mojligt och tiden for manuell hantering goras så kort som mpjlig. Dårtill bor gårdor konstrueras så att yttre storning, manuell hantering och begrånsning av djurens rorelsefrihet minimeras. Transporter bor genomforas med forsiktighet och med undvikande av manuell hantering vid lastning och lossning. Slakt bor foretagas omedelbart, dvs vid gårdan. Transport av levande djur, samt hållandet av djur i gårdor eller fillor i vantan på slakt innebår att kottkvaliteten forsåmras och bor således undvikas.Kenttâtutkimus porojen stressistâ erilaisten kâsittelymuotojen yhteydessà.Abstract in Finnish / Yhteenveto: Stressin merkitystâ poroissa tutkitaan laumoissa, joissa kàytetààn erilaisia kokoamis - ja kàsittelymenetelmià. Kaikissa laumoissa, jotka olivat joutuneet alttiiksi erilaisille ajomuodoille, oli teuraselàimissâ stressin aiheuttamia vammoja mahaverenvuotojen, lihasrappeutumien ja verikuvan muutosten muodossa. Lôydetyt vammat ja muutokset olivat stressin aiheuttamat siina suhteessa kuin elaimet olivat siihen joutuneet. Kàsin pitely ja elàinten liikuntavapauden rajoittuminen havaittiin olevan yksi pààsiallisista stressintekijôistà. Oli esillà myôs voimakas osoitus kasvavan vaikutuksen toistuvasta stressistâ. Moottoriajoneuvojen (helikopteri, moottori-kelkka) kàyttô ajossa sekà elàvien elàinten tiekuljetus nayttivàt olevan merkittàvià stressitekijôità. Voidaan todeta, ettà erilaiset kasittelymuodot ovat aiheuttaneet stressin erilaisia asteita. Stressin vaikutuksen taso aiheutti eri asteisia negatiivisia vaikutuksia osittain huonontuneeseen lihan laatuun. Nainollen pitàà ajot suorittaa niin varovaisesti kuin mahdollista ja aika kàsin pitelyyn tehtàvà niin lyhyeksi kuin mahdollista. Sen lisàksi pitàà aidât rakentaa niin, ettà ulkoista hàirintàà, kàsin pitelyà ja elàinten liikuntavapauden rajoitusta vàhennetààn. Kuljetukset pitàà suorittaa varovaisuudella ja koettaa vàlttàà kàsin pitelyà kuormauksessa ja purkauksessa. Teurastaminen pitàà suorittaa vâlittômàsti, toisin sanoen aidan luona. Elàvien elàinten kuljetus, sekà elàinten pitàminen aitauksissa tai tarhoissa teurastamista odotellessa aiheuttaa lihalaadun huonontumiseen ja pitàà nàin ollen vàlttàà
Skew Category Algebras Associated with Partially Defined Dynamical Systems
We introduce partially defined dynamical systems defined on a topological
space. To each such system we associate a functor from a category to
\Top^{\op} and show that it defines what we call a skew category algebra . We study the connection between topological freeness of
and, on the one hand, ideal properties of and, on
the other hand, maximal commutativity of in . In
particular, we show that if is a groupoid and for each e \in \ob(G) the
group of all morphisms is countable and the topological space
is Tychonoff and Baire, then the following assertions are equivalent:
(i) is topologically free; (ii) has the ideal intersection property,
that is if is a nonzero ideal of , then ; (iii) the ring is a maximal abelian complex subalgebra of . Thereby, we generalize a result by Svensson, Silvestrov
and de Jeu from the additive group of integers to a large class of groupoids.Comment: 16 pages. This article is an improvement of, and hereby a replacement
for, version 1 (arXiv:1006.4776v1) entitled "Category Dynamical Systems and
Skew Category Algebras
Influence of slaughter age and carcass suspension on meat quality in Angus heifers
This study investigated the effects of pelvic suspension and slaughter age on longissimus thoracis et lumborum (LTL) from 40 heifers with at least 75% Angus breeding. A total of 20 heifers were slaughtered directly from pasture at 18 months of age, and carcass sides were hung either by the Achilles tendon or the pelvic bone. The other 20 heifers were assigned to an additional winter housing period and slaughtered at 22 months of age; carcass sides were hung only by Achilles suspension. All carcasses were electrically stimulated and assessed according to the EUROP carcass classification system. In addition, the LTL muscles were aged for 7 or 14 days before meat quality was evaluated for intramuscular fat (IMF), drip loss, colour, shear force, compression and sensory analysis. The 22-month-old heifers were heavier, fatter and had more IMF than 18-month-old heifers. Conformation scores (muscling) did not differ between the two slaughter groups. Pelvic suspension reduced both between- and within-animal
variation for peak force, total energy and compression peak force. For the 18-month-old heifers, pelvic suspension also decreased peak force, total energy and compression variables for the LTL muscles from both ageing periods, whereas Achilles-suspended
samples had lower shear force values only at day 14. Sensory analysis showed that pelvic-suspended sides had greater tenderness, lower bite resistance, less threadiness, higher juiciness and meat flavour and less visible marbling than meat from
Achilles-suspended sides. Pelvic-suspended sides at 18 months of age were similar in peak force and total energy values to the 22-month-old heifers. The importance of ageing the Achilles-suspended sides was more obvious for samples from 18-month-old
heifers than from the 22-month-old animals. The correlations between the different instrumental measurements and sensory tenderness were considerably higher for carcasses suspended by the Achilles tendon (r = -520.55 to 0.20) than for those hung
by the pelvic bone (r = -520.25 to 0.19). More correlations between sensory-evaluated tenderness and shear variables were significant after 7 days (n = 6) of ageing than after 14 days (n = 4) of ageing. This study clearly shows the benefits of pelvic suspension, which reduces the need for additional feeding after pasture
fish freshness decay measurement with a colorimetric artificial olfactory system
Abstract This paper reports about the application of an artificial olfactory system based on optical imaging technology. This arrangement is formed by a distributed layer of chemical indicators illuminated by a computer screen and imaged by a digital camera. The system has been applied to monitor the freshness decay in fish. The set of indicators is formed by porphyrinoids and acid–base indicators, this combination provides an optimal capture of the process with some of the indicators sensitive to first stage, when the product is still fresh, and others more sensitive to the last part of the freshness deca
Two-degree-of-freedom controller design for an ill-conditioned distillation process using µ-synthesis
The structured singular value framework is applied to a distillation benchmark problem formulated for the 1991 IEEE Conference on decision and control (CDC). A two degree of freedom controller, which satisfies all control objectives of the CDC problem, is designed using /spl mu/-synthesis. The design methodology is presented and special attention is paid to the approximation of given control objectives into frequency domain weights
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