160 research outputs found
Modelling industry dynamics in agriculture
Die Struktur der Landwirtschaft hat sich in vielen westlichen LĂ€ndern grundlegend geĂ€ndert. In Westdeutschland, zum Beispiel, hat die Anzahl der Betriebe deutlich abgenommen, wĂ€hrend die durchschnittliche BetriebsgröĂe von 7,4 ha im Jahr 1950 auf 42,9 ha im Jahr 2013 stieg. Um diese Entwicklung zu verstehen, mĂŒssen insbesondere die begrenzten ProduktionskapazitĂ€ten berĂŒcksichtigt werden, die hinsichtlich der verfĂŒgbaren landwirtschaftlichen NutzflĂ€che oder der ehemaligen Milchquote existieren. Solche KapazitĂ€tsbeschrĂ€nkungen erzeugen einen direkten Zusammenhang zwischen dem Wachsen und Schrumpfen von Betrieben, da die Expansionsmöglichkeiten eines einzelnen Betriebes von frei werdenden KapazitĂ€ten anderer Betriebe abhĂ€ngen. Aus diesem Grund wird hier zunĂ€chst ein dynamisch stochastisches Gleichgewichtsmodell entwickelt, das auf mikroökonomischen Entscheidungen basiert und Markteintritt/-austritt fĂŒr den Fall ausgeschöpfter ProduktionskapazitĂ€ten darstellt. Der KapazitĂ€tspreis ist dabei marktrĂ€umend in dem Sinne, dass die Anzahl neuer Produktionseinheiten mit den aufgegebenen ĂŒbereinstimmen muss. Die Industrie konvergiert unter diesen Bedingungen gegen ein stationĂ€res Gleichgewicht, in dem Ein- und Austritt vorkommen, die GröĂenverteilung jedoch unverĂ€ndert bleibt. Die Anpassung an diesen Zustand wird u.a. beschleunigt, wenn die fixen Eintrittskosten sinken. Eine Version des Modells wird dann auf den westdeutschen Milchsektor angewendet, um den Einfluss einer Quote auf den Strukturwandel zu untersuchen. Verglichen mit dem Szenario freien Wettbewerbs hemmt eine nicht-handelbare Quote die Anpassungsprozesse, wĂ€hrend eine handelbare Quote Marktaustritte fördern und zu einer höheren durchschnittlichen ProduktivitĂ€t fĂŒhren kann. Die Phase nach einer Quotenabschaffung ist geprĂ€gt von enormen KapazitĂ€tsausweitungen und stark fallenden Preisen, falls die fixen Eintrittskosten niedrig sind. Diese Entwicklung ist weniger stark ausgebildet fĂŒr höhere Eintrittskosten.The agricultural industry in Western countries has undergone a substantial structural change. In West Germany, for instance, the number of farms declined notably during the last decades while the average farm size increased from 7.4 ha in 1950 to 42.9 ha in 2013. A factor that needs to be considered when explaining this development is the limited sectoral production capacity, which exists in terms of agricultural land or the former milk quota regime. This limited capacity generates a direct interrelation between farm growth and farm shrinkage as a single farm''s investment option depends crucially on the possible release of production capacity by competitors. The contribution of this thesis is twofold: First, a dynamic stochastic equilibrium model is developed that accounts for microeconomic decision-making and represents an industry operating at an upper capacity limit. The capacity price is determined endogenously such that it offsets the mass of entering and exiting firms in an equilibrium. It is proven that the industry tends to a stationary equilibrium in the long-run, in which entry and exit still occur but the firm size distribution remains constant. Moreover, the adjustment speed to this steady state increases if either the discount factor or the fixed entry costs decrease. Second, the impact of a production quota on industry dynamics is assessed with regard to the former milk quota regime. After calibrating the model to the West German dairy sector, the quota constrained industry performance is compared to a quota free setup. While a non-tradable quota slows down the adjustment processes within the industry, a tradable production quota can stimulate firm turnover and lead to a higher average productivity level. If the entry costs are rather low, the transition phase after a quota removal is characterised by an enormous expansion of production capacity and a considerable output price drop. This development is less pronounced though for higher entry costs
Treatment of chronic endometritis with proteolytic enzymes
Deckblatt-Impressum
persönlicher Dank
Inhaltsverzeichnis
AbkĂŒrzungsverzeichnis
Einleitung
LiteraturĂŒbersicht
Material und Methoden
Ergebnisse
Diskussion
Zusammenfassung
Summary
Literaturverzeichnis
Anhang
Danksagung
SelbstÀndigkeitserklÀrungZiel dieser Studie war es, die EffektivitÀt der Behandlung chronischer
Endometritiden beim Rind mit dem EnzymprÀparat Masti Veyxymà zu beurteilen.
Die Feldstudie wurde in Brandenburg auf zwei kommerziellen
Milcherzeugerbetrieben mit je etwa 750 MilchkĂŒhen durchgefĂŒhrt. Bei allen
Tieren wurde zwischen dem 21. und 27. Tag post partum eine erste
gynÀkologische Untersuchung, Puerperalkontrolle (PK 1) mittels Palpation des
Uterus durchgefĂŒhrt. Tiere in Betrieb A, die bei der rektalen Untersuchung
keinen vaginalen Ausfluss als Anzeichen einer Endometritis aufwiesen, wurden
zusÀtzlich vaginoskopisch untersucht. Bei pathologischem Ausfluss oder
palpatorisch feststellbarem Uterusinhalt wurden die KĂŒhe in die Studie
aufgenommen und anhand ihrer Transpondernummer zufÀllig einer von drei
Behandlungsgruppen zugeordnet. Tiere der Enzymgruppe erhielten intrauterin
proteolytische Enzyme (Masti VeyxymÂź, 20 ml, Veyx-Pharma GmbH, Schwarzenborn,
Deutschland) verabreicht. Tiere der PGF2α \- Gruppe wurden intramuskulÀr mit
500 g Closprostenol (PGF VexyÂź forte, Veyx-Pharma GmbH. Schwarzenborn,
Deutschland) behandelt. Tieren der TrÀgersubstanzgruppe wurde die Matrix des
EnzymprÀparates intrauterin verabreicht (20 ml, Veyx-Pharma GmbH,
Schwarzenborn, Deutschland). Die Matrix enthielt keine Enzyme. Alle Tiere der
Behandlungsgruppen wurden 14 Tage nach der PK 1 erneut rektal und
vaginoskopisch untersucht (PK 2, 35. 41. Tag pp.). Die KĂŒhe wurden
unabhÀngig vom Ergebnis der gynÀkologischen Untersuchung entsprechend ihrer
Gruppenzugehörigkeit ein zweites Mal behandelt. Insgesamt wurden 1422 Tiere
untersucht, von denen 583 (41,0 %) eine chronische Endometritis aufwiesen. In
die Auswertung gingen 566 Tiere ein. Hinsichtlich der klinischen Heilungsrate
konnte in keinem der beiden Betriebe ein signifikanter Unterschied zwischen
den drei Behandlungsgruppen festgestellt werden. In Betrieb A wurde in der
PGF2α \- Gruppe eine numerisch höhere Heilungsrate erzielt. Beim Vergleich der
Fruchtbarkeitskennzahlen konnten in den Betrieben keine signifikanten
Unterschiede zwischen den drei Behandlungsgruppen festgestellt werden. Es
fielen die insgesamt deutlich besseren Ergebnisse fĂŒr die
Fruchtbarkeitsleistung in Betrieb B auf. Die Zugehörigkeit zu Betrieb B hatte
einen signifikant positiven Effekt auf den Erstbesamungserfolg (OR = 2,26) und
die GĂŒstzeit (HR = 1,25) der KĂŒhe. FĂŒr AltkĂŒhe wurde eine signifikant
geringere Wahrscheinlichkeit tragend zu werden (OR = 0,57) festgestellt. FĂŒr
Erstkalbinnen war die Wahrscheinlichkeit, frĂŒher besamt zu werden, signifikant
höher als fĂŒr AltkĂŒhe (HR = 0,83). Die Aussicht auf eine frĂŒhe erfolgreiche
Besamung war fĂŒr die Erstkalbinnen auch signifikant besser (HR = 0,69 Die
Ergebnisse zeigen, dass andere Faktoren als die Behandlungsgruppe, wie das
Alter der KĂŒhe oder die Betriebszugehörigkeit einen entscheidenden Einfluss
auf Heilungsraten und die Fruchtbarkeitsleistung hatten. Faktoren wie das
Fruchtbarkeitsmanagement, Stallhygiene und FĂŒtterung hatten in den Betrieben
vermutlich einen groĂen Einfluss auf den Krankheitsverlauf und die
Fruchtbarkeitsleistung der Tiere mit Endometritiden.The object of this study was to evaluate the efficacy of a treatment of
chronic endometritis with proteolytic enzymes (Masti VeyxymÂź). The field trial
was conducted on two commercial dairy farms in the region of Brandenburg,
Germany, with approximatly 750 animals. All cows received a first post partum
check (PPC 1) by rectal palpation of the uterus between 21 and 27 days in milk
(DIM). Animals on farm A that did not show vaginal discharge as a sign for
chronic endometritis were additionally examined by vaginoscopy. Dairy cows
with pathological discharge or enlarged uterus were as enroled in the study
and were randomly assigned to one out of three treatment groups according to
their identification number. In group "enzymes" cows received an intrauterine
treatment with 20 ml of a solve containing proteolytic enzymes (Masti VeyxymÂź,
Veyx-Pharma GmbH, Schwarzenborn, Germany). In group "PGF 2α" animals received
an intramuscular injection of 0,5 mg Cloprostenol (PGF Veyx forteÂź, Veyx-
Pharma GmbH, Schwarzenborn, Germany). In group "matrix" cows received an
intrauterine application of the matrix containing no enzymes (20 ml, Veyx-
Pharma GmbH, Schwarzenborn, Germany). In all cows a second post partum check
(PPC 2) was performed between 35 and 41 DIM using rectal palpation and
vaginoscopy. Cows were treated a second time irrespectively of the
gynocological examination. A total of 1422 cows were examined and 583 of them
(41,0 %) showed signs of chronic endometritis. Out of these 566 were evaluated
in the study. With regard to clinical cure rate there was no significant
difference between the three treatment groups. Group "PGF 2α" achieved the
highest clinical cure rate on farm A. Regarding the reproductive performance
there were no significant differences between farm A and B and between the
three treatment groups. Farm B showed a generally higher reproductive
performance. There was a significant positive effect concerning the first
service rate (OR = 2,26) and days open (HR = 1,25) for dairy cows on farm B.
Multiparous cows showed a significantly lower odds for pregnancy (OR = 0,57).
In addition, there was a significant higher chance for primiparous cows for an
earlier first (HR = 0, 83) and successfull insemination (HR = 0,69) compared
to multiparous cows. These results showed out that other factors than
treatment group, i.e.patity and farm play an important role concerning
clinical cure rate and reproductive performance. Factors like reproduction
management, hygiene and nutrititon on farms seem to have a great impact on
aetiopathology and reproductive performance of cows with endometritis
LÀndervergleichende Analyse von AufklÀrungsquoten
Die AufklĂ€rungsquoten ĂŒber alle Delikte sowie fĂŒr einzelne Delikte fallen je nach Bundesland sehr unterschiedlich aus. Die Unterschiede der AufklĂ€rungsquoten ĂŒber alle Delikte zwischen den LĂ€ndern sind nahezu vollstĂ€ndig auf Unterschiede der Deliktsstruktur zwischen den LĂ€ndern zurĂŒckzufĂŒhren. Je nach Anteil der Delikte am Fallaufkommen, die generell leichter zu ermitteln sind, fĂ€llt die AufklĂ€rungsquote ĂŒber alle Delikte unterschiedlich hoch aus.
Die deliktsspezifischen Unterschiede der AufklĂ€rungsquoten zwischen den LĂ€ndern erklĂ€ren sich zu einem erheblichen Anteil durch das unterschiedliche Fallaufkommen: Dieser Zusammenhang dĂŒrfte wiederum auf KriminalitĂ€tsformen zurĂŒckzufĂŒhren sein, die generell schwerer zu ermitteln sind, z.B. international agierende oder professionell arbeitende TĂ€ter.
Hingegen liegt insgesamt kein Hinweis darauf vor, dass AufklÀrungsquoten das Fallaufkommen beeinflussen, da sie z.B. eine abschreckende Wirkung entfalten
Nobel and Novice: Author Prominence Affects Peer Review
Peer-review is a well-established cornerstone of the scientific process, yet it is not immune to status bias. Merton identified the problem as one in which prominent researchers get disproportionately great credit for their contribution while relatively unknown researchers get disproportionately little credit.1 We measure the extent of this effect in the peer-review process through a pre-registered field experiment. We invite more than 3,300 researchers to review a paper jointly written by a prominent author â a Nobel laureate â and by a relatively unknown author â an early-career research associate â, varying whether reviewers see the prominent authorâs name, an anonymized version of the paper, or the less well-known authorâs name. We find strong evidence for the status bias: while only 23 percent recommend ârejectâ when the prominent researcher is the only author shown, 48 percent do so when the paper is anonymized, and 65 percent do so when the little-known author is the only author shown. Our findings complement and extend earlier results on double-anonymized vs. singleanonymized review2,3,4,5,6,7 and strongly suggest that double-anonymization is a minimum requirement for an unbiased review process
Investment Preferences and Risk Perception: Financial Agents versus Clients
We study three fundamental components of financial agency settings: Perception and communication of investment profiles, the interaction of agentsâ and clientsâ preferences, and the role of (non-)monetary incentives. The perception of investment profile terminology is very heterogeneous, resulting in substantial miscommunication between clients and agents. Financial agents show a high willingness to implement their clientsâ preferred investment profiles independent of monetary incentives. Agentsâ investments for their clients are biased by their own investment preferences
Probing the momentum relaxation time of charge carriers in ultrathin semiconductor layers
We report on a terahertz time-domain technique for measuring the momentum
relaxation time of charge carriers in ultrathin semiconductor layers. The phase
sensitive modulation technique directly provides the relaxation time.
Time-resolved THz experiments were performed on n-doped GaAs and show precise
agreement with data obtained by electrical characterization. The technique is
well suited for studying novel materials where parameters such as the charge
carriers' effective mass or the carrier density are not known a priori
IPC2008-64315 HIGH END INSPECTION BY FILMLESS RADIOGRAPHY ON LSAW LARGE DIAMETER PIPES FROM EUROPIPE
ABSTRACT Pipes for transportation of combustible media are subject to the most severe safety requirements. In order to guarantee best performance during construction and long term services the level of quality and the productivity are continuously increased. After many years of experience with the FilmlessRadiography (FLORAD) for internal process control (detection of typical weld seam defects like slag and pores), EUROPIPE has eventually invested in the digital X-ray inspection technology for the final release. Therewith the classic X-ray film has been replaced, the environmental impact due to chemicals reduced and the complete NDT process enhanced. By the availability of safe digital images via computer network it became in addition much easier for third party inspectors to monitor the release process. Furthermore the use of a professional data storage system guarantees a safe and traceable long term archival storage with a quick access to all data within minutes. The new installation consists of two separate X-ray chambers. In each chamber two digital detector arrays (DDA) and two X-ray tubes are installed to inspect the weld seam at the pipe ends and areas having indications from the automated ultrasonic testing. EUROPIPE is the first company which has implemented this technology in a highly automated serial production of large diameter pipes
Identification of Naturally Processed Hepatitis C Virus-Derived Major Histocompatibility Complex Class I Ligands
Fine mapping of human cytotoxic T lymphocyte (CTL) responses against hepatitis C virus (HCV) is based on external loading of target cells with synthetic peptides which are either derived from prediction algorithms or from overlapping peptide libraries. These strategies do not address putative host and viral mechanisms which may alter processing as well as presentation of CTL epitopes. Therefore, the aim of this proof-of-concept study was to identify naturally processed HCV-derived major histocompatibility complex (MHC) class I ligands. To this end, continuous human cell lines were engineered to inducibly express HCV proteins and to constitutively express high levels of functional HLA-A2. These cell lines were recognized in an HLA-A2-restricted manner by HCV-specific CTLs. Ligands eluted from HLA-A2 molecules isolated from large-scale cultures of these cell lines were separated by high performance liquid chromatography and further analyzed by electrospray ionization quadrupole time of flight mass spectrometry (MS)/tandem MS. These analyses allowed the identification of two HLA-A2-restricted epitopes derived from HCV nonstructural proteins (NS) 3 and 5B (NS31406â1415 and NS5B2594â2602). In conclusion, we describe a general strategy that may be useful to investigate HCV pathogenesis and may contribute to the development of preventive and therapeutic vaccines in the future
Rule Extraction From Binary Neural Networks With Convolutional Rules for Model Validation
Classification approaches that allow to extract logical rules such as decision trees are often considered to be more interpretable than neural networks. Also, logical rules are comparatively easy to verify with any possible input. This is an important part in systems that aim to ensure correct operation of a given model. However, for high-dimensional input data such as images, the individual symbols, i.e. pixels, are not easily interpretable. Therefore, rule-based approaches are not typically used for this kind of high-dimensional data. We introduce the concept of first-order convolutional rules, which are logical rules that can be extracted using a convolutional neural network (CNN), and whose complexity depends on the size of the convolutional filter and not on the dimensionality of the input. Our approach is based on rule extraction from binary neural networks with stochastic local search. We show how to extract rules that are not necessarily short, but characteristic of the input, and easy to visualize. Our experiments show that the proposed approach is able to model the functionality of the neural network while at the same time producing interpretable logical rules. Thus, we demonstrate the potential of rule-based approaches for images which allows to combine advantages of neural networks and rule learning
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