292 research outputs found
On Modeling and Nonlinear Model Reduction in Automotive Systems
The current control design development process in automotive industry and elsewhere involves many expensive experiments and hand-tuning of control parameters. Model based control design is a promising approach to reduce costs and development time. In this process low complexity models are essential and model reduction methods are very useful tools. This thesis combines the areas of modeling and model reduction with applications in automotive systems. A model reduction case study is performed on an engine air path. The heuristic method commonly used when modeling engine dynamics is compared with a more systematic approach based on the balanced truncation method.The main contribution of this thesis is a method for model reduction of nonlinear systems. The procedure is focused on reducing the number of states using information obtained by linearization around trajectories. The methodology is closely tied to existing theory on error bounds and good results are shown in form of examples such as a controller used in real-world cars. Also, a model of the exhaust gas oxygen sensor, used for air-fuel ratio control in automotive spark-ignition engines, is developed and successfully validated
Vancomycin resistant enterococci in Swedish broilers
Vancomycin resistance enterococci (VRE) are an important cause of nosocomial infections. Presence of VRE in farm animals constitute a reservoir of resistance that can spread to humans via the food-chain and is due to extensive use of the growth promoter avoparcin conferring cross-resistance to vancomycin.
Since 2000, the occurrence of VRE among Swedish broilers has increased in the absence of any obvious selective pressure as avoparcin has not been used since 1984. Also, the increased occurrence seemed to be due to spread of one clone of VRE.
The work of this thesis confirms that the increased occurrence of VRE is caused by the spread of one predominant clone. Both the predominant and the minority clones are E. faecium with plasmid mediated vanA gene.
The vanA gene is transferrable from the predominant and several of the minority clones. Thus, the predominance of one clone is not due to that the resistance is untransferable from the clones. It also confirms that VRE among Swedish broilers have a potential for zoonotic spread of the vanA gene. Plasmid addiction systems are most likely not involved in the retention of the vanA gene as there is a near absence of such systems among VRE from Swedish broilers. Decreased susceptibility to the ionophore narasin can be co-transferred with the vanA gene from the predominant and some of the minority clones. Thereby the use of narasin for coccidial prophylaxis could contribute to retention of the vanA gene. The traits are probably located close to each other so when retaining the decreased susceptibility to narasin, the enterococci also retain the vanA gene.
Broilers arriving to the farms are colonized with VRE persisting in the broiler houses. Differences in occurrence of VRE among farms indicate that the occurrence of VRE can be reduced. Furthermore, a reduction in the contamination of the broiler houses can be achieved by disinfection with a method combining steam and formaldehyde. Subsequently, this could reduce the occurrence of VRE in Swedish broiler production on the whole.
Further research should focus on the role of narasin in the VRE epidemiology as well as exploring the possibility to eliminate VRE from Swedish broiler production
Predicting self-assembled patterns on spheres with multi-component coatings
Interactions between the components in many-body systems can give rise to
spontaneous formation of complex structures. Usually very little is known about
the connection between the interactions and the resulting structure. Here we
present a theory for self-assembling pattern formation in multi-component
systems, formulated as an analytic technique that predicts morphologies
directly from the interactions in an effective model. As a demonstration we
apply the method to a model of alkanethiols on spherical gold particles,
successfully predicting its morphologies and transitions as a function of the
interaction parameters. This system is interesting because it has been
suggested to provide an effective route to produce patchy colloids.Comment: 5 pages, 4 figure
Proof of concept for eradication of vancomycin resistant Enterococcus faecium from broiler farms
BACKGROUND - Vancomycin resistant enterococci (VRE) in Swedish broiler production has been shown to persist at farms between batches. The aim of this study was therefore to determine the possibility to eliminate VRE by disinfection of compartments in broiler houses as a proof of concept.
FINDINGS - VRE could not be detected in environmental samples from the disinfected test compartments in the broiler houses but was detected in environmental samples from the control compartments. The proportion of broilers colonized with VRE decreased in both the test and the control compartments.
CONCLUSIONS - The results are promising and show that the occurrence of VRE in broiler houses can be reduced by adequate cleaning and disinfection with a combination of steam and formaldehyde
Förskrivning av antibiotika till hund vid veterinÀrhögskolan i Nantes, Frankrike
The purpose of this retrospective study was to investigate the prescription of antibiotics to dogs at the small animal clinic at Ecole Nationale Vétérinaire, Nantes, France. The purpose was also to compare the possible prescription patterns in France with those seen in a similar study by Petersson (2003) at the small animal clinic at the Swedish University of Agricultural Sciences, Uppsala.
Antibiotics are very important in veterinary medicine and are used both to treat infections and to prevent them. The use of antibiotics however is not without complications and the risk of developing antimicrobial resistance is of most concern. Resistance has been shown to exist against all currently known antibiotics and potentially all pathogenic bacteria could develop resistance to one or more antibiotics.
This study analysed the case records for all dogs presented to the small animal clinic at Ecole Nationale Vétérinaire, Nantes, France during October 2001 and March 2002 to identify patients which were treated with systemic antibiotics. For these cases the antibiotic used, classified according to the ATCvet system, and the indication for use was noted.
A total of 292 cases (146 per month) resulted in administration of systemic antibiotics. Substances from seven ATCvet groups and a product containing a combination of metronidazole and spiramycin were prescribed during October 2001. During March 2002 antibiotics from only five ATCvet groups and again the combination of metronidazole and spiramycin were prescribed. During both October 2001 and March 2002 ÎČ-lactams accounted for about three quarters of all antibiotics prescribed, which is roughly the same as in the Swedish study (Peterson, 2003). The relative proportions of aminopenicillins and cefalosporins were equivocal during October 2001 and March 2002. The proportion of ÎČ-lactam antibiotics containing amoxicillin potentiated with clavulanic acid was one-seventh during October 2001 and one fifth during March 2002. The main reason given for administering ÎČ-lactam antibiotics was for prophylactic use, primarily peri- and post-operatively. Cefalosporins were also commonly used for problems in cutis or subcutis .
Apart from ÎČ-lactam antibiotics the combination metronidazole and spiramycin was the antibiotic prescribed most frequently. The difference in the number of prescriptions in October 2001 compared with March 2002 is, however, large. During October 2001 the combination metronidazole and spiramycin represent just over ten percent of the total prescriptions whereas during March 2002 it makes up no less than twenty percent. Any reason for this divergence in the prescription is not known. The main use of the metronidazole and spiramycin combination is prophylactic, either at a plain dental descaling or at surgical operations, mainly various dental procedures.
The predominant prophylactic use of antibiotics is notable. Especially since the Swedish Veterinary Associations antibiotic policy for dog and cat medical care (Bergvall, 2002) stress that antibiotics should only be used prophylactically peri- and post-operatively where the risk of infection is either great or could be devastating for the individual. In many of the occasions where antibiotics have been used prophylactically in this study are however, minor surgical operations such as standard castrations.
Even if it is not confirmed this work indicates that the prescription of systemic antibiotics at the small animal clinic at Ecole Nationale Vétérinaire, Nantes, France is less stringent than what is the case at the small animal clinic at the Swedish University of Agricultural Sciences, Uppsala. Established however is the fact that at the small animal clinic at Ecole Nationale Vétérinaire, Nantes, France antibiotics are generally prescribed with a broader activity than at the small animal clinic at the Swedish University of Agricultural Sciences, Uppsala.Syftet med detta arbete var att studera antibiotikaförskrivningen vid smÄdjurskliniken pÄ
Ecole Nationale Vétérinaire, Nantes, Frankrike. Förhoppningen var Àven att kunna jÀmföra
eventuella mönster i förskrivningen dÀr med vad som setts i en likartad studie av Petersson
(2003) vid Klinikcentrum, Sveriges Lantbruksuniversitet, Uppsala.
Antibiotika Àr en, inom veterinÀrmedicinen, mycket viktig sorts lÀkemedel och anvÀnds bÄde
för att bota infektioner samt för att motverka att de uppstÄr. AnvÀndningen av antibiotika Àr
dock inte helt okomplicerad med risken för resistensutveckling som kanske den största
negativa faktorn. Resistens mot i alla idag kÀnda antibiotika existerar och i princip alla
patogena bakterier Àr potentiellt resistenta mot ett eller flera antibiotika.
I denna studie har alla journaler för alla hundar som konsulterade smÄdjurskliniken pÄ Ecole
Nationale Vétérinaire, Nantes, Frankrike under oktober 2001 respektive mars 2002
kontrollerats för huruvida systemisk behandling med antibiotika satts in. NÀr sÄ var fallet
noterades antibiotikasort, uppdelat efter ATCvet grupper, samt diagnos/diagnoser.
Totalt sett resulterade 292 besök (146 vardera mÄnaden) i behandling med systemisk
antibiotika. Substanser frÄn sju olika ATCvet grupper samt ett kombinationspreparat med
metronidazol och spiramycin förskrevs under oktober 2001. Under mars 2002 Ä andra sidan
förskrevs det antibiotika endast frÄn fem ATCvet grupper, samt kombinationen av
metronidazol och spiramycin. Under bĂ„de oktober 2001 och mars 2002 var andelen ïżœ-
laktamantibiotika som förskrevs runt tre fjÀrdedelar, vilket Àr ungefÀr detsamma som i
undersökningen gjord i Sverige (Petersson, 2003). Den inbördes fördelningen mellan
aminopenicilliner och cefalosporiner var i princip helt jÀmn bÄde under oktober 2001 och
mars 2002. Andelen av den förskrivna ïżœ-laktamantibiotika som utgjordes av amoxicillin i
kombination med klavulansyra var cirka en sjundedel under oktober 2001 och en femtedel
under mars 2002. Största anvĂ€ndningen av ïżœ-laktamantibiotika har varit profylaktisk, och dĂ„
frÀmst vid olika operationer. För cefalosporiner Àr Àven infektioner i hud och/eller underhud
en vanlig indikation.
Efter ïżœ-laktamantibiotika Ă€r det kombinationen av metronidazol och spiramycin som stĂ„tt
förskrivits flest gÄnger. Skillnaden i förskrivning mellan oktober 2001 och mars 2002 Àr dock
stor. Under oktober 2001 utgör kombinationen av metronidazol och spiramycin drygt tio
procent av den totala förskrivningen medan den under mars 2002 utgör hela tjugo procent.
NÄgon egentlig förklaring till denna skillnad Àr inte kÀnd. AnvÀndningen av kombinationen
metronidazol och spiramycin Àr frÀmst profylaktisk. Antingen vid ren tandskrapning eller vid
operationer, och dÄ frÀmst olika munhÄleingrepp.
Att den profylaktiska anvÀndningen av antibiotika Àr sÄ pass stor Àr intressant. Speciellt
eftersom Sveriges veterinÀrförbunds antibiotikapolicy för hund- och kattsjukvÄrd (Bergvall,
2002) menar att antibiotika endast ska anvÀndas profylaktiskt vid operationer dÀr risken för
efterföljande infektion Àr stor eller dÀr en sÄdan skulle vara förödande för individen. MÄnga
av de besök dÀr antibiotika anvÀnts profylaktiskt Àr dock smÀrre operationer exempelvis
normalkastrationer.
Ăven om det inte Ă€r helt klarlagt tyder arbetet pĂ„ att förskrivningen av systemisk antibiotika
vid smÄdjurskliniken pÄ Ecole Nationale Vétérinaire, Nantes, Frankrike Àr mindre restriktiv
Àn vid Klinikcentrum, Sveriges Lantbruksuniversitet, Uppsala. Klart Àr dock att det vid
smÄdjurskliniken pÄ Ecole Nationale Vétérinaire, Nantes, Frankrike generellt anvÀnds
antibiotika med bredare aktivitet Àn vid Klinikcentrum, Sveriges Lantbruksuniversitet,
Uppsala
PrissÀttningen pÄ europeiska fotbollsarenor
I denna uppsats undersöks vilka prisdeterminanterna Àr för fotbollsbiljetter, sÄledes vad som styr vilken kostnad konsumenten möter för att besöka en fotbollsmatch. UtgÄngspunkten för arbetet Àr den nya vÄgen av nybyggnationer av fotbollsarenor i Sverige, och att samtliga av dessa kan klassificeras som postmoderna arenor. Detta innebÀr att de erbjuder mer Àn enbart en ÄskÄdarplats för en fotbollsmatch. Dessa arenor skapar ett mervÀrde för konsumenten genom att Àven erbjuda möjlighet till annan typ av konsumtion, dÄ dessa postmoderna arenor som regel Àven har tillgÄng till bar, restaurang och souvenirbutik. Genom att undersöka troliga prisdeterminanter, sÄ som lagets och arenans kvalitet, konkurrens frÄn annat lag i den berörda marknaden och efterfrÄga pÄ biljetter, har jag sökt finna en formel för hur fotbollsklubbar prissÀtter. Jag fann samband mellan biljettpris och samtliga av ovanstÄende variabler. Resultatet av rapporten Àr sÄledes att kvalitet, bÄde pÄ arenorna och pÄ lagen i de sex undersökta ligorna, har en signifikant effekt pÄ biljettpriset. Jag undersökte Àven om högre rankade, och dÀrmed i princip större klubbar, prisdiskriminerade i högre grad Àn mindre, i denna analys fanns inget samband
SolitĂ€ra manifest - En jĂ€mförelse avseende poetologiska ansprĂ„k och poetiska praktiker hos Ăyvind Fahlström och Isidore Isou
Uppsatsen avser kartlĂ€gga de poetologiska och poetiska kontaktytor som kan anas mellan den svenske poeten Ăyvind Fahlströms konkreta poesi och den rumĂ€nsk-franske poeten Isidore Isous lettrism. DĂ„ man i tidigare forskning kring Fahlström och den konkreta poesins villkor ofta nĂ€mner Isou och det lettristiska avantgardet som poetologiskt nĂ€rbeslĂ€ktade, rĂ„der det vidare en brist i mer analytiska ansatser kring de bĂ„da poeternas poetiska sammankoppling. Syftet med denna uppsats Ă€r att försöka avtĂ€cka denna lĂ€nk. Genom att jĂ€mföra de bĂ„da diktarnas manifest (poetiken); Fahlströms "HĂ€tila ragulpr pĂ„ fĂ„tskliaben. Manifest för konkret poesi (1953)" med Isous "Le manifeste de la poĂ©sie lettriste (1942)", men Ă€ven det poetiska förkroppsligandets praktiska element (dikterna), belyser denna uppsats de grundlĂ€ggande resonemang som för Fahlström och Isou bildade vĂ„ldet mot skrifttecknets semantiska innebörder. Texten Ă€r indelad i tre tematiska lĂ€sningar av de bĂ„da diktarnas manifest: 1. Manifestens subjekt - hĂ€r undersöks lanseringen av de bĂ„da manifesten, som placeras in i respektive historisk kontext och hur de bĂ„da diktarna framtrĂ€der i sina program. 2. Manifestens morfologi och disposition - i detta avsnitt studeras manifestens formlĂ€ra, dvs. manifestens estetiska grepp och deras uppbyggnad. Det slutliga avsnittet heter: 3. Programmen och dess kvasipoetiska dimensioner - hĂ€r har jag undersökt huruvida poetiken (manifesten) översĂ€tts i poetiska praktiker och produkter (dikter). Uppsatsen avslutas med att redogöra hur Fahlström och Isou stundtals intar olika stĂ€llningar med sina respektive poetiska skolor, men belyser framförallt de likartade element som existerar dem emellan
Prevalence and antibiotic resistance of Salmonella enterica in poultry and raw meat in the Can Tho province, Vietnam
The aim of this study was to get an overview of prevalence and resistance patterns of Salmonella enterica in chicken as well as antibiotic use and knowledge of antibiotic resistance among farmers in the Can Tho region, Vietnam. Material was sampled on local farms and markets during six weeks in October to November of 2008. Twelve markets were selected and each market was sampled once for a total of 96 samples of neck skin of chicken. In addition 20 farms were selected and rectal swabs were collected on a total of 96 chickens. Analyses of market samples were based on the principles of the Nordic Committee on Food Analysis but adapted to local practises. The sampling from farms was based on procedures used in humans and studies of other bacteria in chicken, thus being more uncertain in its outcome. A total of 11 samples, nine from farms and two from markets, were positive or uncertain on polyvalent antiserum testing and hence sent to Sweden for final confirmation and serotyping. Surprisingly only one out of the eleven isolates was shown to belong to the Salmonella enterica species, namely S. Enteritidis. The reason to the large number of negative samples has to be contributed to the inexperience of myself as well as to the use of modified methods in a foreign laboratory environment. The positive sample was tested for antibiotic resistance showing resistance to four different antibiotics; ampicillin, streptomycin, sulfamethoxazol and tetracyclin. Farmer awareness was studied through a questionnaire and showed low knowledge of antibiotic resistance development and moreover that antibiotics are used as a prophylactic and dependent on availability rather than in regard to its effect on specific disease causing agents.MÄlet med studien var att undersöka prevalens och antibiotikaresistensmönster för
Salmonella enterica i kyckling i Can Tho regionen i södra Vietnam. Utöver detta
syftade studien till att undersöka kunskap och medvetenhet hos
fjÀderfÀproducenterna i regionen avseende antibiotikaanvÀndning och
resistensutveckling. Provtagningen utfördes pÄ lokala gÄrdar och marknader under
sex veckor i oktober och november 2008. Tolv marknader valdes ut och varje
marknad provtogs en gÄng. Sammanlagt togs 96 prover av nackskinn frÄn
kyckling. Utöver detta valdes 20 gÄrdar ut, frÄn vilka totalt 96 kloakprover frÄn
levande kyckling erhölls. Marknadsprover analyserades enligt NMKL-metoden,
men modifierades efter lokala förutsÀttningar. GÄrdsproverna följde ingen
etablerad metod utan utgick frÄn hur analysmetoder pÄ prover frÄn mÀnniska gÄr
till samt erfarenheter frÄn SVA pÄ liknande provtagning vid undersökning av
andra bakterier. SÄledes var resultatet av den senare analysen mer osÀkert. Totalt
11 prover, nio gÄrdsprover och tvÄ marknadsprover, var positiva eller tveksamma
vid agglutination med polyvalent antiserum och skickades till Sverige för
slutgiltig konfirmering och serotypning. FörvÄnande nog tillhörde endast ett av
elva skickade bakterieisolat Salmonella enterica, serotypat som S. Enteritidis.
Orsaken till det stora antalet osÀkra och vidare negativa proverna mÄste hÀrledas
till personlig brist pÄ erfarenhet av bakteriologiska studier samt anvÀndandet av
modifierade och relativt oprövade metoder i en frÀmmande laboratoriemiljö. Det
positiva provet testades för antibiotikaresistens och visade sig vara en
multiresistent stam med höga MIC-vÀrden mot följande antibiotika; ampicillin,
streptomycin, sulfamethoxazol och tetracyklin. Producentmedvetenhet
undersöktes med ett skriftligt frÄgeformulÀr och visade pÄ en mycket liten
kunskap om antibiotikaresistensutveckling samt att antibiotika anvÀnds
profylaktiskt och efter tillgÄng och kostnad snarare Àn med avseende pÄ aktuell
sjukdomsagens och passande antibiotikabehandling
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