How deep is deep enough? -- Quantifying class separability in the hidden layers of deep neural networks

Deep neural networks typically outperform more traditional machine learning models in their ability to classify complex data, and yet is not clear how the individual hidden layers of a deep network contribute to the overall classification performance. We thus introduce a Generalized Discrimination Value (GDV) that measures, in a non-invasive manner, how well different data classes separate in each given network layer. The GDV can be used for the automatic tuning of hyper-parameters, such as the width profile and the total depth of a network. Moreover, the layer-dependent GDV(L) provides new insights into the data transformations that self-organize during training: In the case of multi-layer perceptrons trained with error backpropagation, we find that classification of highly complex data sets requires a temporal {\em reduction} of class separability, marked by a characteristic 'energy barrier' in the initial part of the GDV(L) curve. Even more surprisingly, for a given data set, the GDV(L) is running through a fixed 'master curve', independently from the total number of network layers. Furthermore, applying the GDV to Deep Belief Networks reveals that also unsupervised training with the Contrastive Divergence method can systematically increase class separability over tens of layers, even though the system does not 'know' the desired class labels. These results indicate that the GDV may become a useful tool to open the black box of deep learning

Social Network Services: Competition and Privacy

Social Network Services (SNS) business models highly depend on the gathering and analyzation of user data to obtain an advantage in competition for advertising clients. Nevertheless, an extensive collection and analysis of this data poses a threat to users’ privacy. Based on an economic perspective it seems rational for Social Network Operators (SNO) to ignore the users’ desire for privacy. However, privacy-friendly services might have the potential to earn users’ trust, leading to an increased revelation of personal data. Addressing these issues, we examine the existing privacy problem in SNS in the context of competition between SNO to investigate whether competition tend to enhance user privacy or whether it is the root of its violation. Therefore, this paper investigates the interconnectedness of the market structure and privacy problems in SNS. After analyzing the users’ and the advertisers’ side of SNS, their competitiveness and its influence on user privacy are examined

Planar n-in-n quad module prototypes for the ATLAS ITk upgrade at HL-LHC

In order to meet the requirements of the High Luminosity LHC (HL-LHC), it will be necessary to replace the current tracker of the ATLAS experiment. Therefore, a new all-silicon tracking detector is being developed, the so-called Inner Tracker (ITk). The use of quad chip modules is intended in its pixel region. These modules consist of a silicon sensor that forms a unit along with four read-out chips. The current ATLAS pixel detector consists of planar n-in-n silicon pixel sensors. Similar sensors and four FE-I4 read-out chips were assembled to first prototypes of planar n-in-n quad modules. The main focus of the investigation of these modules was the region between the read-out chips, especially the central area between all four read-out chips. There are special pixel cells placed on the sensor which cover the gap between the read-out chips. This contribution focuses on the characterization of a non-irradiated device, including important sensor characteristics, charge collection determined with radioactive sources as well as hit efficiency measurements, performed in the laboratory and at testbeams. In addition, first laboratory results of an irradiated device are presented

Zur Perspektive von Mentor*innen auf Schulpraktika im Fach Sport: Eine Interviewstudie zum Potenzial von Mentoring als Teil beruflichen Lernens von Sportlehrkräften

Die vorliegende Untersuchung fokussiert Schulpraktika als Anstoß beruflicher Lernprozesse von Mentor*innen. Forschungsmethodisch ist die Studie in ein forschungsorientiertes Entwicklungsprojekt eingegliedert, in dem eine Maßnahme entwickelt wurde, durch die eine verstärkte Kooperation zwischen den Dozent*innen der universitären Begleitseminare zu den Praktika und den Mentor*innen erreicht werden soll. Dies wird als phasenübergreifende Kooperation bezeichnet (Wibowo & Krieger, 2019a). Zur Evaluation der Maßnahme wurden 13 Mentor*innen aus zwei Kohorten dazu interviewt, inwiefern phasenübergreifende Kooperation in Schulpraktika als Lerngelegenheit wahrgenommen wird. Die Ergebnisse deuten darauf hin, dass das Zustandekommen von beruflichen Lernprozessen durch die organisatorische und inhaltliche Flexibilität der Maßnahme, die Konkretheit des Seminarinhalts, die Passung der Inhalte zu individuellen Überzeugungen und das Abwägen eins Gesamt-Kosten-Nutzen-Verhältnisses beeinflusst wird

Nasal IgE in subjects with allergic and non-allergic rhinitis

Purpose: The prevalence of "ocal allergic rhinitis" within individuals suffering from perennial rhinitis remains uncertain, and patients usually are diagnosed with non-allergic rhinitis. The aim of this study was to evaluate the prevalence of a potential "local allergic rhinitis" in subjects suffering from non-allergic rhinitis in a non-selected group of young students. Methods: 131 students (age 25.0 +/- 5.1 years) with a possible allergic rhinitis and 25 non-allergic controls without rhinitis symptoms (age 22.0 +/- 2.0 years) were recruited by public postings. 97 of 131 students with rhinitis were tested positive (>= 3 mm) to prick testing with 17 frequent allergens at visit 1. Twenty-four 24 subjects with a house dust mite allergy, 21 subjects with a non-allergic rhinitis, and 18 non-allergic controls were further investigated at visit 2. Blood samples were taken, and nasal secretion was examined. In addition, all groups performed a nasal provocation test with house dust mite (HDM). Results: In serum and nasal secretion, total IgE and house dust mite specific IgE significantly differed between HDM positive subjects and controls. However, no differences between non-allergic subjects and control subjects were quantifiable. Neither a nasal provocation test nor a nasal IgE to HDM allergens showed a measurable positive response in any of the non-allergic rhinitis subjects as well as the healthy controls, whilst being positive in 13 subjects with HDM allergy. Conclusions: Nasal IgE is present in subjects with HDM allergy, but not in non-allergic rhinitis. In the investigated non-selected population, exclusive local production of IgE is absent. By implication, therefore, our findings challenge the emerging concept of local allergic rhinitis