188 research outputs found
Processable Fully Aromatic Quinoline-based Polymers
No full textQuinoline-based homo- and copolymers have been synthesized by the acid-catalyzed Friedlaender condensation between bis(o-aminoketone)s and silicon-containing bis(ketomethylene) monomers. The polymers contain quaternary silicon atoms and are fully aromatic; they show improved solubility compared to known polyquinolines with approximately unchanged softening and decomposition temperatures of the final material. A new solubilization method was developed for these materials. In addition two block copolymers based on an aramid block containing fluorene cardo units and polyquinoline were prepared
Parsimonious models for inverse problems
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Previous issue date: 2019-08-20Embargo set by: Seth Robbins for item 113849
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Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemThis dissertation can be coarsely divided into two parts: Chapters 1 and 2 study the problem of the multidimensional filter bank design and data-driven adaptation, while Chapters 3 to 5 focus on variations of optical tomography.
Chapter 1 describes a fast way to estimate the extremal values of a trigonometric polynomial given samples from the polynomial. This work came about from a simple question: Can we determine whether the Discrete-Time Fourier Transform of a multidimensional discrete index signal reaches zero, given only its Discrete Fourier Transform? The answer is yes— provided that the signal has small support and its samples do not vary too much. This property unlocks new possibilities for the numerical design of multidimensional, multirate, perfect reconstruction filter banks; we conclude by designing a curvelet-like filter bank.
Chapter 2 focuses on data-adaptive sparse representations; that is, a sparse representation learned directly from the data itself. These representations are usually described as modeling and acting on small image patches. We show that many of the existing sparse representations can instead be thought of as filter banks, thus linking the local properties of a patch-based model to the global properties of a convolutional model. We then use the results on trigonometric polynomials developed in Chapter 1 as the foundation for a new algorithm to learn perfect reconstruction filter banks that sparsify data. Our learned model outperforms local, patch- based transform learning approaches in image denoising tasks while benefiting from additional flexibility in the design process.
Chapter 3 marks the transition to the second family of topics in this dissertation. In this chapter, we review a particular optical tomographic imaging: Interferometric Synthetic Aperture Microscopy (ISAM). ISAM allows for rapid, non-invasive imaging of quasi-transparent objects in three spatial dimensions from measurements of back-scattered light. In this modality, volumetric images are formed by solving the inverse scattering problem using perturbative methods. The resulting image reconstruction algorithms have efficient numerical implementations. The usual ISAM image reconstruction algorithms are well-suited for data collected from a single focal plane, with Tikhonov regularization, and/or if Gaussian noise is present. In these situations a non-iterative image reconstruction algorithm is applicable. However, when an iterative solution is required, the perturbative ISAM model leads to artifacts in the reconstructed image.
In Chapter 4, we present a new approximation to the ISAM forward model. This model facilitates the combination of fast numerical algorithms and iterative image reconstruction. We construct the singular value decomposition of our new approximate ISAM operator and investigate the resolution of the imaging system. In Chapter 5, we combine ISAM with imaging spectroscopy to determine spatial morphology and chemical composition in three spatial dimensions. We assume the target has a low-rank structure; physically, this implies the target is composed of a few distinct chemical species. We call this the N-species approximation. We use this low-rank structure to reduce the amount of data needed to solve the inverse scattering problem.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01The student, Luke Pfister, accepted the attached license on 2019-08-19 at 14:58.The student, Luke Pfister, submitted this Dissertation for approval on 2019-08-19 at 15:03.This Dissertation was approved for publication on 2019-08-20 at 16:09.DSpace SAF Submission Ingestion Package generated from Vireo submission #14429 on 2020-02-28 at 17:20:08Embargo set by: Seth Robbins for item 113849
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Inequality of pay in Germany, late 15th century to 1889.
No full textThis study examines three dimensions of wage inequality in Germany during four centuries (1485 - 1889), namely sectoral wage variations, skill premium as an indicator of the influence of human capital on wage income, and gender difference. It opens with an overview of the nominal and real wages of urban workers from the 16th to the 19th century. It examines the wages of the following groups: (1) for urban construction, the wages of skilled craftsmen are compared with the wages of unskilled workers (skill premium); (2) wages in agriculture are compared with wages in the industrial sector; (3) the wage evolution of the female agricultural labour force is analysed in relation to the wages of male agricultural workers. For this purpose, two data sets on wages recently compiled by the author are used, which are supplemented with additional information, in particular on wages in agriculture (see Pfister 2019, 217-222). The data set provided here includes a series on skill premiums in urban construction, a series on the daily wages of male farmworkers at the Nordkirchen and Westphalia estates, and synthetic series on nominal wages in urban construction and on the consumer goods price index over the long period 1500-1913. 1. the skill premium (Table A-01) The skill premium is measured here as the wage differential by which the daily wages of skilled craftsmen exceed those of unskilled workers (e.g. 0.51 means that the daily wages of skilled craftsmen are 51% higher than those of unskilled workers). Data from 18 cities are available for the determination of the skill premium. The database of prices and wages until 1850 compiled by Pfister (2017; GESIS ZA8636) represents the main source for the daily wages of both skilled and unskilled construction workers. For the period from 1840 to 1880, the wage data compiled in Pfister (2018; GESIS ZA8710) on the urban building trade is used as a supplementary source. Appendix 1 documents at the level of individual cities the sources and the years for which wage data are available. It should be emphasized that the data set is characterized by a high heterogeneity with regard to the trades covered, the length of the data series and the data density. For the construction of a time series of the skills premium at the level of Germany as a whole, the data are averaged over centered five-year periods (1483-1487, 1488-1482, .... 1883-1887) due to the low data density - there are on average only about three observations per year. The skill premium is then first calculated individually for each city and each five-year period for which data are available for both skilled and unskilled construction workers; a total of 393 data points are thus obtained. In a second step, an unbalanced panel regression with fixed effects for the cities and the five-year periods is estimated using feasible GLS, with the error variants partitioned by time periods (for details, see Pfister 2019, 218). A time series can be calculated on the basis of the regression coefficients for the five-year periods; it was scaled with the mean skill premium in the period 1773-1778. This is because the data density is highest in this period, as data are available for ten cities. The result is shown in Pfister (2019, 228, Figure 4) and made available here in Table A-01. 2. wages of agricultural workers (Table A-02) Wage data in agriculture are usually quoted as daily wages. They differ according to the type of activity and whether the agricultural worker receives food and accommodation or not. In the study only such wages without provision of food and accommodation are taken into account. The monetary amounts are standardized to Marks per day. The study uses the account books of a large aristocracy possession, the results of surveys carried out in connection with land reform and the compilation of land tax registers, social statistical surveys and a re-analysis of the database by Neumann (1911) to construct a series of farmworkers´ wages for Westphalia for the period around 1730-1892. The individual data points are defined as follows: 1730-1810: Average daily wage on the Nordkirchen aristocratic estate, centered ten-year periods. Source: original source are the account books; collection of wage data and construction of a wage index in Bracht / Pfister (2019, Annex A3). 1818: Daily wage of men in Westphalia; average value for the three administrative districts for so-called domestic work. The values for the administrative districts are mean values of data at district level. Source: Kuczynski (1961, vol. 1, p. 361 f., 371); original source is a survey by the Prussian authorities. 1825-1845: Daily wage of men in Westphalia, centered five-year periods. Values for the entire Kingdom of Prussia were scaled to the level of Westphalia using the value for Westphalia in 1848/50 (see below). Source: Reanalysis of the Neumann database (2011); see Annex 2. 1848/50: Daily wages of men in Westphalia, mean value of wages for harvesting work and for other work, average of the data for the three administrative districts. Source: Meitzen (1866, 91). 1861/65: Daily wages of men in Westphalia, total average above minimum and maximum wages for harvest work, other work in summer and winter as well as across the three administrative districts. Source: Meitzen (1866, 92-114). 1868: Day wage of men in Westphalia. Source: Meitzen: Hamann (1945, 200). 1873: Daily wages of men in Westphalia; working conditions in which food is not provided at the workplace (or: inclusion of food in the wage rate). Overall average of summer and winter wages, permanent and temporary workers and across the three administrative districts. Source: von der Goltz (1875: 48-53). 1885: Daily wage of men in Westphalia, average of 81 counties. Source: Schmitz (1886, 26-29). At least for Westphalia the values seem too low; for a critique of this source see Kattwinkel (1912, 2-5). 1892: Daily wages of men in Westphalia; working conditions in which food is not provided at the workplace (or: inclusion of food in the wage rate). Overall average of summer and winter wages, permanent and temporary workers and across the three administrative districts. Source: Kärger et al. (1892, vol. 1: 225-34). For further information on farm workers´ wages, especially on the merging of these sources in the first half of the 19th century, see Pfister (2019, 219-222). 3. nominal wage index and consumer goods price index, 1500-1913 (Table A-03) The table contains the rows underlying Figure 1 in Pfister (2019, 213). They were constructed as follows: The nominal wage index combines the following three series, which were linked in 1850 and 1888, respectively: 1500-1850 Daily wage of unskilled workers in 18 towns from Pfister (2017, Appendix S3, GESIS ZA8636, Table A-03-02) 1850-1888 Annual wages in industry and trade from Pfister (2018, Annex A3, GESIS ZA8710) 1888-1913 Annual wages in industry and trade from Hoffmann (1965, Table II/104, pp. 468-471) The consumer goods price index combines the following three series, which were linked in 1850 and 1888 respectively: 1500-1850 Annual cost of a consumer basket in grams of silver from Pfister (2017, Appendix S3, GESIS ZA8636, Table A-03-02) 1850-1888 Consumer goods price index from Pfister (2018, Annex A3, GESIS ZA8710) 1888-1913 Consumer goods price index from Orsagh (1969, 481) Table A-03 also contains a real wage index, which simply represents the quotient of the nominal wage index and the consumer goods price index. The following data series are included in this study: A.01 skill premium in urban construction, 1485-1885. A.02 Daily wage for agricultural workers in Nordkirchen and Westphalia, 1730-1892. A.03 Nominal wage, consumer price index and real wage (indices 1913=100, aggregated indices), 1500-1913. Note: Studies closely related to this study are: ZA8636: Pfister, U., Nominal Wages and Consumer Goods Prices in 18 German Cities, 1500-1850. ZA8710: Pfister, U., Wages and Prices of Consumer Goods in Germany, 1850 to 1889.Diese Studie untersucht drei Dimensionen der Lohnungleichheit in Deutschland in vier Jahrhunderten (1485 - 1889), nämlich die sektoralen Lohnvariationen, die Fähigkeitsprämie (skill premium) als Indikator für den Einfluss des Humankapitals auf das Lohneinkommen, und die Geschlechterdifferenz. Sie beginnt mit einem Überblick der nominalen und realen Löhne der Arbeiter in den Städten vom 16. bis zum 19. Jahrhundert. Dabei werden die Löhne folgender Gruppen untersucht: (1) für das städtische Baugewerbe werden die Löhne von gelernten Handwerkern den Löhnen von ungelernten Arbeitern gegenübergestellt (skill premium); (2) werden die Löhne in der Landwirtschaft mit den Löhnen im industriellen Sektor verglichen; (3) wird die Lohnentwicklung der weiblichen Arbeitskräfte in der Landwirtschaft in Bezug zu den Löhnen männlicher Landarbeiter analysiert. Hierfür wird auf zwei kürzlich vom Autor zusammengestellten Datensätze zu Löhnen zurückgegriffen, die ergänzt werden mit zusätzlichen Informationen, insbesondere über die Löhne in der Landwirtschaft (siehe hierzu Pfister 2019, 217-222). Der hier bereit gestellte Datensatz umfasst eine Reihe zur Fähigkeitsprämie (skill premium) im städtischen Baugewerbe, eine Reihe zum Tagelohn männlicher Landarbeiter auf dem Gut Nordkirchen bzw. Westfalen, sowie synthetische Reihen zum Nominallohn im städtischen Bauhandwerk und zum Konsumgüterpreisindex über den langen Zeitraum 1500–1913. 1. Die Fähigkeitsprämie (skill premium; Tabelle A-01) Die Fähigkeitsprämie (skill premium) wird hier gemessen als das Lohndifferenzial, um welches der Tagelohn gelernter Bauhandwerker denjenigen ungelernter Arbeiter übertrifft (z. B. 0,51 meint, dass der Tagelohn gelernter Handwerker 51% über demjenigen von ungelernten Arbeitern liegt). Für ihre Bestimmung stehen Angaben aus 18 Städten zur Verfügung. Die von Pfister (2017; GESIS ZA8636) erstellte Datenbasis von Preisen und Löhnen bis 1850 stellt die Hauptquelle für die Tagelöhne sowohl der gelernten Bauhandwerker als auch der ungelernten Arbeiter dar. Für die Zeit von 1840 bis 1880 wird ergänzend auf die in Pfister (2018; GESIS ZA8710) zusammengestellten Lohndaten zum städtischen Bauhandwerk zurückgegriffen. Anhang 1 dokumentiert auf der Ebene einzelner Städte die Quellen und die Jahre, für die Lohnangaben verfügbar sind. Es ist zu betonen, dass der Datensatz von einer hohen Heterogenität hinsichtlich der erfassten Handwerksberufe, der Länge der Datenreihen und der Datendichte gekennzeichnet ist. Für die Konstruktion einer Zeitreihe der Fähigkeitsprämie auf der Ebene von Gesamtdeutschland werden aufgrund der geringen Datendichte – es gibt im Durchschnitt nur etwa drei Beobachtungen pro Jahr – die Daten über zentrierte Fünfjahreszeiträume (1483-1487, 1488-1482, .... 1883-1887) gemittelt. Die Qualifikations- oder Fähigkeitsprämie (skill premium) wird dann zunächst individuell für jede Stadt und jeden Fünfjahreszeitraum berechnet, für den Daten sowohl für gelernte als auch ungelernte Bauarbeiter vorliegen; insgesamt kommen so 393 Datenpunkte zustande. In einem zweiten Schritt wird mittels feasible GLS eine unbalancierte Panelregression mit fixed effects für die Städte und die Fünfjahresperioden geschätzt, wobei die Fehlervarianzen nach den Zeitperioden partitioniert werden (für Details s. Pfister 2019, 218). Auf der Basis der Regressionskoeffizienten für die Fünfjahresperioden lässt sich eine Zeitreihe berechnen; sie wurde mit der mittleren Fähigkeitsprämie in der Periode 1773-1778 skaliert. Dies erfolgte deshalb, weil in dieser Periode die Datendichte am höchsten ist, denn es liegen Angaben für zehn Städte vor. Das Ergebnis wird in Pfister (2019, 228, Abbildung 4) gezeigt und hier in Tabelle A-01 zugänglich gemacht. 2. Löhne von Landarbeitern (Tabelle A-02) Lohnangaben in der Landwirtschaft sind üblicherweise als Tagelöhne notiert. Sie unterscheiden sich nach Art der Tätigkeit und danach, ob der Landarbeiter Kost und Unterkunft erhält oder nicht. In der Studie werden nur solche Löhne ohne Bereitstellung von Kost und Unterkunft berücksichtigt. Die Geldbeträge sind auf Mark pro Tag vereinheitlicht. Die Studie nutzt die Rechnungsbücher eines großen Adelsbesitzes, die Ergebnisse von Erhebungen, die im Zusammenhang mit der Landreform und der Erstellung von Grundsteuerkatastern erfolgten, sozialstatistische Erhebungen sowie eine Reanalyse der Datenbasis von Neumann (1911) um für Westfalen eine Reihe von Landarbeiterlöhnen für den Zeitraum ca. 1730-1892 zu konstruieren. Die einzelnen Datenpunkte sind wie folgt definiert: 1730-1810: Mittlerer Tagelohn auf dem Adelsgut Nordkirchen, zentrierte Zehnjahresperioden. Quelle: ursprüngliche Quelle sind die Rechnungsbücher; Erfassung von Lohndaten und Konstruktion eines Lohnindexes in Bracht / Pfister (2019, Anhang A3). 1818: Tagelohn von Männern in Westfalen; Mittelwert für die drei Regierungsbezirke für sogenannte häusliche Arbeit. Die Werte für die Regierungsbezirke sind Mittelwerte von Angaben auf Kreisebene. Quelle: Kuczynski (1961, Bd. 1, S. 361 f., 371); ursprüngliche Quelle ist eine Erhebung der preußischen Behörden. 1825-1845: Tagelohn von Männern in Westfalen, zentrierte Fünfjahresperioden. Werte für das gesamte Königreich Preußen wurden anhand des Wertes für Westfalen in den Jahren 1848/50 (s. unten) auf das Niveau von Westfalen skaliert. Quelle: Reanalyse der Datenbasis von Neumann (2011); s. Anhang 2. 1848/50: Tagelohn von Männern in Westfalen, Mittelwert der Löhne für Erntearbeiten und für sonstige Arbeiten, Mittelwert der Angaben für die drei Regierungsbezirke. Quelle: Meitzen (1866, 91). 1861/65: Tagelohn von Männern in Westfalen, Gesamtdurchschnitt über Minimal- und Maximallöhne für Erntearbeiten, andere Arbeiten im Sommer und Winterarbeiten sowie über die drei Regierungsbezirke hinweg. Quelle: Meitzen (1866, 92-114). 1868: Tagelohn von Männern in Westfalen. Quelle: Hamann (1945, 200). 1873: Tagelohn von Männern in Westfalen; Arbeitsverhältnisse, bei denen am Arbeitsplatz keine Verköstigung erfolgt (oder: Einbezug der Verköstigung in den Lohnsatz). Gesamtdurchschnitt über Sommer- und Winterlöhne, dauerhaft und temporär beschäftigte Arbeiter und über die drei Regierungsbezirke hinweg. Quelle: von der Goltz (1875: 48-53). 1885: Tagelohn von Männern in Westfalen, Mittelwert von 81 Landkreisen. Quelle: Schmitz (1886, 26-29). Mindestens für Westfalen scheinen die Werte zu tief; für eine Kritik dieser Quelle s. Kattwinkel (1912, 2-5). 1892: Tagelohn von Männern in Westfalen; Arbeitsverhältnisse, bei denen am Arbeitsplatz keine Verköstigung erfolgt (oder: Einbezug der Verköstigung in den Lohnsatz). Gesamtdurchschnitt über Sommer- und Winterlöhne, dauerhaft und temporär beschäftigte Arbeiter und über die drei Regierungsbezirke hinweg. Quelle: Kärger et al. (1892, Bd. 1: 225-34). Für weitere Informationen über Landarbeiterlöhne, insbesondere auch zum Zusammenführen der genannten Quellen in der ersten Hälfte des 19. Jahrhunderts, s. Pfister (2019, 219-222). 3. Nominallohnindex und Konsumgüterpreisindex, 1500–1913 (Tabelle A-03) Die Tabelle enthält die Reihen, die Abbildung 1 in Pfister (2019, 213) zugrundliegen. Sie wurden folgendermaßen konstruiert: Der Nominallohnindex kombiniert folgende drei Reihen, die 1850 bzw. 1888 verkettet wurden: 1500-1850 Tagelohn ungelernter Arbeiter in 18 Städten aus Pfister (2017, Anhang S3, GESIS ZA8636, Tabelle A-03-02) 1850-1888 Jahreslöhne in Industrie und Handwerk aus Pfister (2018, Anhang A3, GESIS ZA8710) 1888-1913 Jahreslöhne in Industrie und Handwerk aus Hoffmann (1965, Tabelle II/104, S. 468-471) Der Konsumgüterpreisindex kombiniert folgende drei Reihen, die 1850 bzw. 1888 verkettet wurden: 1500-1850 Jährliche Kosten eines Konsumgüterkorbs in Gramm Silber aus Pfister (2017, Anhang S3, GESIS ZA8636, Tabelle A-03-02) 1850-1888 Konsumgüterpreisindex aus Pfister (2018, Anhang A3, GESIS ZA8710) 1888-1913 Konsumgüterpreisindex aus Orsagh (1969, 481) Tabelle A-03 enthält auch einen Reallohnindex, der einfach den Quotienten von Nominallohnindex und Konsumgüterpreisindex darstellt. Folgende Datenreihen sind in der vorliegenden Studie enthalten: A.01 skill premium (Fähigkeitsprämie) im städtischen Baugewerbe, 1485-1885. A.02 Tagelohn für Arbeiter in der Landwirtschaft in Nordkirchen bzw. Westfalen, 1730-1892. A.03 Nominallohn, Verbraucherpreis-Index und Reallohn (Indizes 1913=100, aggregierte Indizes), 1500-1913. Hinweis: Studien, die mit dieser Studie in engem Zusammenhang stehen, sind: ZA8636: Pfister, U., Nominallöhne und Konsumgüterpreise in 18 deutschen Städten, 1500-1850. ZA8710: Pfister, U., Löhne und Konsumgüterpreise in Deutschland, 1850 bis 1889
Author Correction: Uncoupling of invasive bacterial mucosal immunogenicity from pathogenicity.
No full textISSN:2041-172
Betti Numbers For p-Stable Ideals
No full textthis paper was done while the third author was visiting the University of Kaiserslautern and the Sonderforschungsbereich 343 of University of Bielefeld. He whishes to thank the SFB 343 for its hospitality and support. 1. p\Gamma stable ideals As already mentioned in Introduction one considers the following partial order on N: k p s i
After a Hand Was Lent : Sporadically Experiencing Multisensory Interference During the Rubber Hand Illusion Does Not Shield Against Disembodiment
No full textObservations from multisensory body illusions indicate that the body representation can be adapted to changing task demands, e.g., it can be expanded to integrate external objects based on current sensorimotor experience (embodiment). While the mechanisms that promote embodiment have been studied extensively in earlier work, the opposite phenomenon of, removing an embodied entity from the body representation (i.e., disembodiment) has received little attention yet. The current study addressed this phenomenon and drew inspiration from the partial reinforcement extinction effect in instrumental learning which suggests that behavior is more resistant to extinction when reinforcement is delivered irregularly. In analogy to this, we investigated whether experiencing occasional visuo-motor mismatches during the induction phase of the moving rubber hand illusion (intermittent condition) would result in slower disembodiment as compared to a regular induction phase where motor and visual signals always match (continuous condition). However, we did not find an effect of reinforcement schedule on disembodiment. Keeping a recently embodied entity in the body schema, therefore, requires constant updating through correlated perceptual and motor signals. CC BY 4.0© 2025 The Author(s)Correspondence Address: J. Eck; Department of Psychology III, Julius-Maximilians-Universität Würzburg, Würzburg, Röntgenring 11, 97070, Germany; email: [email protected]; R. Pfister; Trier University, Trier, Johanniterufer 15, 54290, Germany; email: [email protected] research was founded by the German Research Foundation (DFG), DFG PF 853/8-1 and PF853/10–1 and DI 2126/4-1.The publication was supported by the Open Access Fund of Universität Trier and by the German Research Foundation (DFG).</p
Corrigendum to “The classical Artin approximation theorems”
No full textThe purpose of this note is to clarify and complement various places in the article The classical Artin approximation theorems, published in Bull. Amer. Math. Soc. 54 (2017), no. 4, 595–633. A few reasonings in the article may have been difficult to follow or were even problematic. The author is indebted to F. Castro-Jiménez, C. Chiu, R. Ephraim, B. Lamel, S. Perlega, G. Pfister, G. Rond, M. Singer, S. Woblistin, and particularly to an anonymous referee for valuable feedback.</p
Understanding catchment behavior through stepwise model concept improvement
No full textLack of data is one of the main limitations for hydrological modeling. However, it is often used as a justification for over simplifying, poorly performing models. If we want to enhance our understanding of hydrological systems, it is important to fully exploit the information contained in the available data, and to learn from model deficiencies. In this paper, we propose a methodology where we systematically update the model structure, progressively incorporating new hypotheses of catchment behavior. We apply this methodology to the Alzette river basin in Luxembourg, showing how stepwise model improvement helps to identify the behavior of this catchment. We show that the most significant improvement of the evolving model structure is associated to the characterization of antecedent wetness. This is improved accounting for interception, which affects vertical storage distribution, and accounting for rainfall spatial heterogeneity, which influences storage variations in the horizontal dimension. Overall, our results suggested that, due to the damping effect of the basin, the description of fast catchment response benefits more from spatially distributed information than that of slow catchment response.Water ManagementCivil Engineering and Geoscience
[Washington Irving, half-length portrait, three-quarters to the left]
No full textAuthor; U.S. Minister to Spain, 1842-1846.Scratched on back of plate: 250; Washington Irving.Identification from engravings by S. Hollyer and others. The original Plumbe daguerreotype is reproduced in Washington Irving, Mr. Bryant's address... N.Y., G.P. Putnam, 1860, opposite page 38.Copy daguerreotype, reverse of original by John Plumbe.Hallmark: Rinhart 20.Facing the light / H. Pfister. Washington : Smithsonian Institution Press, 1978, p. 329.Original served by appointment only.Produced by Mathew Brady's studio.Transfer; U.S. War College; 1920; (DLC/PP-1920:46153).Forms part of: Daguerreotype collection (Library of Congress)
Detection of Strongylus vulgaris in equine faecal samples by real-time PCR and larval culture – method comparison and occurrence assessment
No full textBACKGROUND: Strongylus vulgaris has become a rare parasite in Germany during the past 50 years due to the practice of frequent prophylactic anthelmintic therapy. To date, the emerging development of resistance in Cyathostominae and Parascaris spp. to numerous equine anthelmintics has changed deworming management and the frequency of anthelmintic usage. In this regard, reliable detection of parasitic infections, especially of the highly pathogenic S. vulgaris is essential. In the current study, two diagnostic methods for the detection of infections with S. vulgaris were compared and information on the occurrence of this parasite in German horses was gained. For this purpose, faecal samples of 501 horses were screened for S. vulgaris with real-time PCR and an additional larval culture was performed in samples of 278 horses. A subset of 26 horses underwent multiple follow-up examinations with both methods in order to evaluate both the persistence of S. vulgaris infections and the reproducibility of each diagnostic method.
RESULTS: The real-time PCR revealed S. vulgaris-DNA in ten of 501 investigated equine samples (1.9%). The larval culture demonstrated larvae of S. vulgaris in three of the 278 samples (1.1%). A direct comparison of the two methods was possible in 321 samples including 43 follow-up examinations with the result of 11 S. vulgaris-positive samples by real-time PCR and 4 S. vulgaris-positive samples by larval culture. The McNemar's test (p-value = 0.016) revealed a significant difference and the kappa values (0.525) showed a moderate agreement between real-time PCR and larval culture.
CONCLUSIONS: The real-time PCR detected a significantly higher proportion of positives of S. vulgaris compared to larval culture and should thus be considered as a routine diagnostic method for the detection of S. vulgaris in equine samples
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