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  1. Book ; Thesis: Kurz- und mittelfristige klinische Ergebnisse nach lumbalen Nucleoplastien

    Brümmer, Nina

    2009  

    Author's details Nina Brümmer
    Language German
    Size 94 S. : Ill., graph. Darst.
    Publishing country Germany
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Bonn, Univ., Diss., 2009
    HBZ-ID HT016100005
    Database Catalogue ZB MED Medicine, Health

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    In stock of ZB MED Cologne/Königswinter

    Shelf markLoan statusLocation
    2011 D 400 order for loan Magazin

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  2. Book ; Online: How to use KL-divergence to construct conjugate priors, with well-defined non-informative limits, for the multivariate Gaussian

    Brümmer, Niko

    2021  

    Abstract: The Wishart distribution is the standard conjugate prior for the precision of the multivariate Gaussian likelihood, when the mean is known -- while the normal-Wishart can be used when the mean is also unknown. It is however not so obvious how to assign ... ...

    Abstract The Wishart distribution is the standard conjugate prior for the precision of the multivariate Gaussian likelihood, when the mean is known -- while the normal-Wishart can be used when the mean is also unknown. It is however not so obvious how to assign values to the hyperparameters of these distributions. In particular, when forming non-informative limits of these distributions, the shape (or degrees of freedom) parameter of the Wishart must be handled with care. The intuitive solution of directly interpreting the shape as a pseudocount and letting it go to zero, as proposed by some authors, violates the restrictions on the shape parameter. We show how to use the scaled KL-divergence between multivariate Gaussians as an energy function to construct Wishart and normal-Wishart conjugate priors. When used as informative priors, the salient feature of these distributions is the mode, while the KL scaling factor serves as the pseudocount. The scale factor can be taken down to the limit at zero, to form non-informative priors that do not violate the restrictions on the Wishart shape parameter. This limit is non-informative in the sense that the posterior mode is identical to the maximum likelihood estimate of the parameters of the Gaussian.

    Comment: technical report, 10 pages
    Keywords Statistics - Machine Learning ; Computer Science - Machine Learning ; Mathematics - Statistics Theory
    Subject code 519
    Publishing date 2021-09-15
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Thesis ; Online: Consumers' perspective on chicken husbandry

    Brümmer, Nanke

    The case of dual-purpose chickens

    2019  

    Abstract: According to several studies, chicken farming is seen as the most controversial form of livestock farming among society. One element that is increasingly noticed and criticised is the culling of day-old male chicks. Annually, in Germany, 45 million male ... ...

    Abstract According to several studies, chicken farming is seen as the most controversial form of livestock farming among society. One element that is increasingly noticed and criticised is the culling of day-old male chicks. Annually, in Germany, 45 million male chicks of layer breeds are culled directly after hatching because the fattening of the males is unprofitable. This applies to both, conventional and organic animal husbandry. Dual-purpose chickens day-old chicks being discussed. They can both, produce meat and lay eggs. The hens lay fewer and smaller eggs than current specialised layers, and the cockerels put on less meat than broilers and need more time and feed to grow, which leads to a higher demand for resources. Consequently, eggs and meat from dual-purpose chickens have a different appearance and are more expensive than products from specialised chickens. Consumers, therefore, play an essential role when it comes to the acceptance and marketability of dual-purpose chickens, as they ultimately decide the success of products at the counter. Therefore, the main objective of this thesis is to analyse consumer perspectives on dual-purpose chickens in order to provide implications and recommendations for policy-makers, economy and research when discussing the use of dual-purpose chicken breeds. In contribution 1, an explorative approach was used to gather insights into the topic. Six focus groups provided findings about consumer perspectives on dual-purpose chickens. The results show that the culling of day-old chicks was known to most of the participants and rejected for ethical reasons. They were aware of few alternatives, and information on dual-purpose chickens and the other alternatives to the culling was given to the participants. The naming was seen as inappropriate and misleading, but the participants were generally in favour of this chicken breed. Some participants raised concerns regarding economic efficiency and higher product prices. For others, ethical values predominated. Additionally, the results ...
    Keywords Text ; ddc:630 ; consumer preferences -- choice analysis -- attitudes -- mixed methods -- dual-purpose chicken -- preference heterogeneity -- ethical matrix -- chicken husbandry -- Verbraucherpräferenzen -- Entscheidungsverhalten -- Einstellungen -- Mixed Methods -- Zweinutzungshuhn -- Präferenzheterogenität -- Ethische Matrix -- Hühnerhaltung
    Subject code 801
    Language English
    Publisher Georg-August-Univ.
    Publishing country de
    Document type Thesis ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Drivers of organic food choice in Germany—the case of young adults

    Brümmer, Nanke / Zander, Katrin

    Organic agriculture. 2020 Dec., v. 10, no. Supplement 1

    2020  

    Abstract: The purpose of this paper is to explore the values that underlie young adults’ purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. A means-end chain analysis of the ... ...

    Abstract The purpose of this paper is to explore the values that underlie young adults’ purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. A means-end chain analysis of the laddering interviews revealed several values of young adults that are relevant for organic food purchase. Values that were found in relation to organic food purchase were security, universalism, hedonism and benevolence. Values related to non-purchase of organic food were security, power, self-direction and hedonism. The results of this study show that both egoistic and altruistic values are relevant for young adults’ organic food purchase intention. When it comes to motivating young adults to become organic consumers, particularly the reasons for not buying organic food ‘too high prices’ and ‘lack of trust’ should be considered when developing well-targeted communication strategies.
    Keywords food choices ; food purchasing ; motivation ; organic foods ; organic production
    Language English
    Dates of publication 2020-12
    Size p. 57-64.
    Publishing place Springer Netherlands
    Document type Article
    Note NAL-AP-2-clean
    ZDB-ID 2587049-X
    ISSN 1879-4246 ; 1879-4238
    ISSN (online) 1879-4246
    ISSN 1879-4238
    DOI 10.1007/s13165-020-00306-2
    Database NAL-Catalogue (AGRICOLA)

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  5. Conference proceedings ; Online: Determinants Of Organic Food Choice In Germany – The Case Of Young Adults

    Brümmer, Nanke / Zander, Katrin

    2021  

    Abstract: The purpose of this paper is to explore the values that underlie young adults purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. The results revealed several values of ... ...

    Abstract The purpose of this paper is to explore the values that underlie young adults purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. The results revealed several values of young adults that are relevant for organic food purchase. Values that were frequently revealed in relation to organic food purchase were well-being, universalism, hedonism and benevolence. Values that were explored in relation to non-purchase of organic food were security, hedonism and self-direction. The findings show that egoistic values were more relevant for young adults organic food purchase intention than altruistic values. The findings of this study can be used by producers and marketers by increasingly considering the values in their marketing strategies.
    Keywords Food systems ; Values ; standards and certification
    Language English
    Publishing country dk
    Document type Conference proceedings ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Determinants of organic food choice in Germany

    Brümmer, Nanke / Zander, Katrin

    The case of young adults

    2021  

    Abstract: The purpose of this paper is to explore the values that underlie young adults purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. The results revealed several values of ... ...

    Abstract The purpose of this paper is to explore the values that underlie young adults purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. The results revealed several values of young adults that are relevant for organic food purchase.Values that were frequently revealed in relation to organic food purchase were well-being, universalism, hedonism and benevolence. Values that were explored in relation to non-purchase of organic food were security, hedonism and self-direction. The findings show that egoistic values were more relevant for young adults organic food purchase intention than altruistic values. The findings of this study can be used by producers and marketers by increasingly considering the values in their marketing strategies.
    Keywords Text ; abstract_or_summary ; ddc:630 ; addering -- means-end chain -- organic food -- purchase behaviour -- values -- young adults
    Subject code 590
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Einstellungen junger Erwachsener zu Bio-Lebensmitteln

    Brümmer, Nanke / Zander, Katrin

    Eine Online-Mixed-Methods-Studie ; Attitudes of young adults towards organic food – an online mixed methods study

    2020  

    Abstract: Wachsende Marktanteile von Bio-Lebensmitteln erfordern das Erreichen neuer Käuferschichten. Eine solche neue Käuferschicht sind junge Erwachsene (18-30 Jahre). Um diese Käuferschicht erfolgreich ansprechen zu können, müssen ihre spezifischen ... ...

    Abstract Wachsende Marktanteile von Bio-Lebensmitteln erfordern das Erreichen neuer Käuferschichten. Eine solche neue Käuferschicht sind junge Erwachsene (18-30 Jahre). Um diese Käuferschicht erfolgreich ansprechen zu können, müssen ihre spezifischen Einstellungen bezüglich des Einkaufs von Bio-Lebensmitteln bekannt sein. Um die Einstellungen von jungen Erwachsenen zu untersuchen, wurde ein Online-Mixed-Methods-Ansatz gewählt. Im ersten qualitativen Schritt wurden drei Online-Gruppendiskussionen realisiert. Darauf aufbauend wurde eine quantitative Online-Befragung durchgeführt. Die Ergebnisse zeigen, dass hohe Tierwohlstandards, Gesundheit, Frische und Umweltschutz die wichtigsten Kaufkriterien für Bio-Lebensmittel sind. Hinderungsgründe für den Kauf sind die hohen Preise und das fehlende Vertrauen in die Zuverlässigkeit der Bioproduktion. Ähnlich wie in früheren Studien zeigen auch junge Erwachsene eine ausgeprägte Präferenz für regionale Produkte und ziehen diese vielfach den ökologischen Produkten vor. Um eine positive Nachfrageentwicklung von jungen Erwachsenen für Bio-Produkte zu befördern, sollten Maßnahmen ergriffen werden, die das Vertrauen in Bio-Lebensmittel steigern und die die regionale Erzeugung fördern.

    Additional demand for organic food requires reaching out for new groups of consumers. One such group is young adults (18 to 30 years). In order to successfully address this group, one should be aware of the specific attitudes towards organic food purchase. In order to analyse the attitudes of young adults, an online mixed method approach was chosen. In the first qualitative step, three online focus groups were realized. Building on this, a quantitative online survey was conducted. The results show that high animal welfare standards, health, freshness and environmental protection are the most important purchasing criteria for organic food. Obstacles for the purchase are the high prices and the lack of trust regarding organic production. Similar to earlier studies, young adults also show a strong preference ...
    Keywords Text ; ddc:300 ; ddc:630 ; Einstellungen -- junge Erwachsene -- Ökolandbau -- Mixed-Methods -- attitudes -- young adults -- organic farming -- mixed methods
    Language German
    Publishing date 2020-12-21
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Drivers of organic food choice in Germany - the case of young adults

    Brümmer, Nanke / Zander, Katrin

    2020  

    Abstract: The purpose of this paper is to explore the values that underlie young adults’ purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. A means-end chain analysis of the ... ...

    Abstract The purpose of this paper is to explore the values that underlie young adults’ purchase motivation of organic food. Online chat-based laddering interviews were conducted with 30 organic and non-organic consumers. A means-end chain analysis of the laddering interviews revealed several values of young adults that are relevant for organic food purchase. Values that were found in relation to organic food purchase were security, universalism, hedonism and benevolence. Values related to non-purchase of organic food were security, power, self-direction and hedonism. The results of this study show that both egoistic and altruistic values are relevant for young adults’ organic food purchase intention. When it comes to motivating young adults to become organic consumers, particularly the reasons for not buying organic food ‘too high prices’ and ‘lack of trust’ should be considered when developing welltargeted communication strategies.
    Keywords Text ; ddc:630 ; Organic food -- Laddering -- Means-end chain -- Young adults -- Consumer behaviour
    Subject code 590
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Book ; Online: Out of a hundred trials, how many errors does your speaker verifier make?

    Brümmer, Niko / Ferrer, Luciana / Swart, Albert

    2021  

    Abstract: Out of a hundred trials, how many errors does your speaker verifier make? For the user this is an important, practical question, but researchers and vendors typically sidestep it and supply instead the conditional error-rates that are given by the ROC/ ... ...

    Abstract Out of a hundred trials, how many errors does your speaker verifier make? For the user this is an important, practical question, but researchers and vendors typically sidestep it and supply instead the conditional error-rates that are given by the ROC/DET curve. We posit that the user's question is answered by the Bayes error-rate. We present a tutorial to show how to compute the error-rate that results when making Bayes decisions with calibrated likelihood ratios, supplied by the verifier, and an hypothesis prior, supplied by the user. For perfect calibration, the Bayes error-rate is upper bounded by min(EER,P,1-P), where EER is the equal-error-rate and P, 1-P are the prior probabilities of the competing hypotheses. The EER represents the accuracy of the verifier, while min(P,1-P) represents the hardness of the classification problem. We further show how the Bayes error-rate can be computed also for non-perfect calibration and how to generalize from error-rate to expected cost. We offer some criticism of decisions made by direct score thresholding. Finally, we demonstrate by analyzing error-rates of the recently published DCA-PLDA speaker verifier.

    Comment: Submitted to Interspeech 2021
    Keywords Computer Science - Sound ; Computer Science - Machine Learning ; Electrical Engineering and Systems Science - Audio and Speech Processing ; Statistics - Machine Learning
    Subject code 501
    Publishing date 2021-04-01
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Book ; Online: A Speaker Verification Backend with Robust Performance across Conditions

    Ferrer, Luciana / McLaren, Mitchell / Brummer, Niko

    2021  

    Abstract: In this paper, we address the problem of speaker verification in conditions unseen or unknown during development. A standard method for speaker verification consists of extracting speaker embeddings with a deep neural network and processing them through ... ...

    Abstract In this paper, we address the problem of speaker verification in conditions unseen or unknown during development. A standard method for speaker verification consists of extracting speaker embeddings with a deep neural network and processing them through a backend composed of probabilistic linear discriminant analysis (PLDA) and global logistic regression score calibration. This method is known to result in systems that work poorly on conditions different from those used to train the calibration model. We propose to modify the standard backend, introducing an adaptive calibrator that uses duration and other automatically extracted side-information to adapt to the conditions of the inputs. The backend is trained discriminatively to optimize binary cross-entropy. When trained on a number of diverse datasets that are labeled only with respect to speaker, the proposed backend consistently and, in some cases, dramatically improves calibration, compared to the standard PLDA approach, on a number of held-out datasets, some of which are markedly different from the training data. Discrimination performance is also consistently improved. We show that joint training of the PLDA and the adaptive calibrator is essential -- the same benefits cannot be achieved when freezing PLDA and fine-tuning the calibrator. To our knowledge, the results in this paper are the first evidence in the literature that it is possible to develop a speaker verification system with robust out-of-the-box performance on a large variety of conditions.
    Keywords Computer Science - Sound ; Computer Science - Machine Learning
    Subject code 006
    Publishing date 2021-02-02
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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