Accumulated Gradient Normalization

This work addresses the instability in asynchronous data parallel optimization. It does so by introducing a novel distributed optimizer which is able to efficiently optimize a centralized model under communication constraints. The optimizer achieves this by pushing a normalized sequence of first-order gradients to a parameter server. This implies that the magnitude of a worker delta is smaller compared to an accumulated gradient, and provides a better direction towards a minimum compared to first-order gradients, which in turn also forces possible implicit momentum fluctuations to be more aligned since we make the assumption that all workers contribute towards a single minima. As a result, our approach mitigates the parameter staleness problem more effectively since staleness in asynchrony induces (implicit) momentum, and achieves a better convergence rate compared to other optimizers such as asynchronous EASGD and DynSGD, which we show empirically.Comment: 16 pages, 12 figures, ACML201

The crucial role of the facilitator

Facilitation is a practice with many areas of application: participatory planning, environmental governance and natural resource management are some areas with a high focus on facilitation. Within these different areas, the practice is supposed to empower citizens, revitalise democracy and tackle the sustainability challenge. With an increasing demand in participatory decision-making, planning and other citizens-based approaches, the demand for facilitation is growing, and so is research regarding the topic. Studies conducted on the field of facilitation have contributed to a better understanding of the practice. However, while research is focusing heavily on involved actors in facilitation, the facilitators’ construction of identity remains under-explored. Previous research focusing on the facilitator identified practical dilemmas facilitators face by looking into deliberative theory. Yet, research on facilitation did not reveal how practitioners construct their identity in a process. This is essential since the role of a facilitator depends on differing ideas practitioners draw on when facilitating. Further, the idea of identity matters insofar as it guides the practitioners work during practicing. Therefore, it is problematic that we know little about how facilitators construct their identity. This thesis addresses this knowledge gap by providing valuable insights into the lifeworld of facilitators in a natural resource management context. Interviews were conducted with practitioners and these are used as a foundation for the thesis. The study uncovers embedded ideas about identity practitioners draw on when facilitating. With the help of frame analysis, I identify underlying ideas and understandings facilitators draw on when constructing their identity. The analysis brought forward four identity frames practitioners draw on when facilitating, whereas some practitioners draw on more than one frame in a facilitated process. The identified frames are an equality frame, authority frame, expert frame, and neutrality frame. Further, the identified frames yield a range of tensions facilitators face when practicing facilitation. First, the results show that there are conflicting identities embedded in facilitation practice. Moreover, tension among the equality and authority frame arise as practitioners are owners of the process using their authority to level out differences among participants while not dominating the process. In addition, facilitators face a dilemma of being experts in the field of facilitation (expert frame) while at the same time not acknowledging the groups’ desires (equality and neutrality frame). The thesis’ strength is the foundation of empirical material and has therefore a high practical value for the practice of facilitation. This study then not only adds a better comprehension of how facilitators construct their identity, but also helps to understand how facilitators approach challenges within the practice of facilitation. Therefore, the thesis yields a contribution to the practical field of facilitation and additionally, adds empirical depth to theoretical work on deliberative democracy. Overall, the conducted frame analysis on interviews with facilitators reveals insights into the practice of facilitation. Thus, this thesis intends to create a basis for reflective practice for practitioners conducting facilitation

Rational Synthesis and Application of Aryl Iodides in Electrochemical Reactions and Theoretical Studies on the CBS Catalyst

Within this dissertation three different projects are discussed. The underlying theme of all projects is the application of computational and/or statistical methods in order to decrease the experimental effort and to increase the information output at the same time. Lewis acid activation of the CBS catalyst was investigated using DFT theory. A new electrosynthetic approach for the synthesis of aryl iodides was developed using design of experiments. In a third project, a new iodide(III) mediated synthesis of isochromanones was investigated

Delayed feedback control of periodic orbits in autonomous systems

For controlling periodic orbits with delayed feedback methods the periodicity has to be known a priori. We propose a simple scheme, how to detect the period of orbits from properties of the control signal, at least if a periodic but nonvanishing signal is observed. We analytically derive a simple expression relating the delay, the control amplitude, and the unknown period. Thus, the latter can be computed from experimentally accessible quantities. Our findings are confirmed by numerical simulations and electronic circuit experimentsComment: 4 pages, Revtex, manuscript also available at ftp://athene.fkp.physik.th-darmstadt.de/pub/publications/wolfram/prl_98a/ or at http://athene.fkp.physik.th-darmstadt.de/public/wolfram_publ.htm

Hinweise zur qualitätsgerechten Planung und Ausführung von Estrich- und Fußbodenkonstruktionen im Wohn-, Gesellschafts- und Industriebau

Fußbodenkonstruktionen als Stiefkind der Planung und Ausführung? Bei der Ausführung von Fußböden gibt es viele Fehlerquellen. Ein umfassendes Kompendium mit Hinweisen aus der Praxis für die Planung und Ausführung von Fußböden ist im Jahr 2000 mit dem FUSSBODENATLAS erschienen; die vorliegende Veröffentlichung wurde in Auszügen diesem Werk entnommen

Causes of brain dysfunction in acute coma: a cohort study of 1027 patients in the emergency department

BACKGROUND: Coma of unknown etiology (CUE) is a major challenge in emergency medicine. CUE is caused by a wide variety of pathologies that require immediate and targeted treatment. However, there is little empirical data guiding rational and efficient management of CUE. We present a detailed investigation on the causes of CUE in patients presenting to the ED of a university hospital. METHODS: One thousand twenty-seven consecutive ED patients with CUE were enrolled. Applying a retrospective observational study design, we analyzed all clinical, laboratory and imaging findings resulting from a standardized emergency work-up of each patient. Following a predefined protocol, we identified main and accessory coma-explaining pathologies and related these with (i.a.) GCS and in-hospital mortality. RESULTS: On admission, 854 of the 1027 patients presented with persistent CUE. Their main diagnoses were classified into acute primary brain lesions (39%), primary brain pathologies without acute lesions (25%) and pathologies that affected the brain secondarily (36%). In-hospital mortality associated with persistent CUE amounted to 25%. 33% of patients with persistent CUE presented with more than one coma-explaining pathology. In 173 of the 1027 patients, CUE had already resolved on admission. However, these patients showed a spectrum of main diagnoses similar to persistent CUE and a significant in-hospital mortality of 5%. CONCLUSION: The data from our cohort show that the spectrum of conditions underlying CUE is broad and may include a surprisingly high number of coincidences of multiple coma-explaining pathologies. This finding has not been reported so far. Thus, significant pathologies may be masked by initial findings and only appear at the end of the diagnostic work-up. Furthermore, even transient CUE showed a significant mortality, thus rendering GCS cutoffs for selection of high- and low-risk patients questionable. Taken together, our data advocate for a standardized diagnostic work-up that should be triggered by the emergency symptom CUE and not by any suspected diagnosis. This standardized routine should always be completed - even when initial coma-explaining diagnoses may seem evident

Biomasseabschätzung im ökologischen Feldfutterbau mittels drohnengestützten RGB-Aufnahmen

Monitoringansätze im ökologischen Futterbau, die den Biomasseertrag über den gesamten Betrieb abschätzen, ermöglichen es dem Landwirt, standortspezifische Managemententscheidungen zu treffen. Die pflanzliche Biomasse und ihre Höhe korrelieren miteinander, wodurch die Höhe des Bestandes zur Ertragsprognose verwendet werden kann. Fernerkundliche Messmethoden sind nützlich, um räumliche Informationen über die Pflanzenhöhe auch über größere Flächen zu erhalten. In dieser Studie wurde eine RGB-Kamera (rot, grün, blau), die an einem kleinen unbemannten Luftfahrzeug (Drohne) angebracht war, zur Ertragsabschätzung in einem ökologischen Futterbauexperiment verwendet. Das Experiment wurde 2016 mit zwei Leguminosen-Grasmischungen (Klee- und Luzernegras) sowie mit ihren reinen Leguminosen und Gräsern angelegt. In der Vegetationsperiode des nächsten Jahres wurden jede zweite Woche RGB-Aufnahmen durchgeführt. Parallel dazu wurden Referenzdaten für die Biomasseerträge und manuelle Höhenmessungen erstellt. 3D-Modelle, die aus den RGB-Aufnahmen erzeugt wurden, wurden zur Berechnung der Bestandeshöhe verwendet. Der Biomasseertrag wurde mit zufriedenstellenden Ergebnissen vorhergesagt

El mecanismo del lavado en trigo

p.179-191Con el fin de estudiar la relación entre la absorción de agua por el grano previa a la cosecha y la calidad comercial, se simularon lluvias de distinta duración en varios estadios posteriores a la madurez fisiológica aplicadas a espigas de un cultivar en dos años. Los granos no incrementaron sustancialmente su contenido de humedad por absorción directa de la lluvia pero sí lo hicieron cuando las espigas permanecieron luego de estar 24 h en condiciones de alta humedad relativa. En ese caso tomaron agua libre retenida en la espiga y agua abosorbida por partes no grano que pasó al grano. Cuando se produjo un incremento de humedad en los granos disminuyó en primer lugar el Peso Hectolítrico (PH), posteriormente se opacó el aspecto externo y en último término cambió la textura interna pasando a una no vitrea