Evidence of negative Poisson's ratio in wood from finite element analysis and off-axis compression experiments

© 2017 The microstructure of wood is highly anisotropic, which suggests that this material could exhibit unusual elastic properties. A few studies have suggested the possibility of auxeticity, or negative Poisson's ratio (NPR) in some wood samples. In order to conclusively confirm that wood does show NPR, we have used a combination of geometric modelling, finite element analysis (FEA) and off-axis compression testing. The geometric model indicates that idealised thin-walled wood cell structures should generate NPR of −1, FEA suggests that more realistic cell arrays can attain NPR, to −0.27, and compression tests show that some NPR – to −0.74 – remains in real wood samples. These results could help design “engineered-wood” laminates products with tailored elastic properties

Recent Advances in Conjugated Polymers for Light Emitting Devices

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review

Globales Lernen als Kriterium für Erwachsenenbildung und Personalentwicklung in Unternehmen

Das Konzept des Globalen Lernens wird mittlerweile in verschiedenen Bildungskontexten umgesetzt. Weit weniger Ansätze gibt es, dieses Konzept, seine Werte und Kompetenz­anforderungen reflektiert in den für nachhaltige Entwicklung besonders kritischen Wirtschaftssektor zu integrieren. Dabei geht es weniger um spektakuläre und wichtige Projekte zur Ressourcenschonung und -rettung, sondern vielmehr um alltägliche Handlungen von Berufstätigen und UnternehmerInnen: um Transparenz in Handlungen und Leistungen, wirtschaftliche und soziale Nachhaltigkeit, Qualität von Leistungen und Prozessen, konstruktiven Umgang mit Diversität und produktiven Einsatz von gesicherten Erkenntnissen im Angesicht komplexer Handlungsfelder. Der vorliegende Beitrag stellt eine Möglichkeit vor, diesen Schritt in den Wirtschaftssektor zu wagen, und erläutert die Umsetzung an einem praktischen Beispiel aus der Branche der Finanzberatung. Fazit der Autoren: Mit der Integration Globalen Lernens in das reale Handeln in Wirtschaftskontexten durch Erwachsenenbildungs- und Personalentwicklungsmaßnahmen und dessen Übernahme in das Zielsystem von Organisationen kommt das Globale Lernen dort an, wo es gebraucht wird: in der Gegenwart und dort, wo über materielle Ressourcen verfügt wird. (DIPF/Orig.)The concept of Global Learning has been implemented in various educational contexts. There are fewer approaches to integrating this concept and its values and competence requirements in a thoughtful way into the economic sector, which is particularly critical to sustainable development. It is less a question of spectacular and important projects to better manage and save resources but rather of the daily activities of employed people and business people: transparency in actions and services, economic and social sustainability, quality of services and processes, constructive dealing with diversity and productive use of indisputable findings in the face of complex spheres of activity. This article ventures a step in the direction of the business sector and explains Global Learning’s implementation with a practical example from the field of financial advising. The author’s conclusion is that with the integration of Global Learning into real action in economic contexts via adult education and human resources measures and its acceptance into the target system of organisations, Global Learning arrives where it is needed: in the present and where material resources are available. (DIPF/Orig.

Globales Lernen in international tätigen Wirtschaftsunternehmen implementieren. Unterstützung ressourcenschonenden und global verantwortlichen Handelns in medial vermittelten Arbeitsgruppen

Der Beitrag stellt einen Entwicklungsansatz zu deren Implementierung in international tätigen Wirtschaftsunternehmen am Beispiel medial vermittelter Arbeitsgruppen dar. Es wird deutlich, dass Wirtschaftsunternehmen durchaus am Globalen Lernen interessiert sind, sofern das Konzept erstens schlüssig in Ziele und Organisation des Unternehmens integriert werden kann und zweitens nachweisbaren ökonomischen Erfolg verspricht. (DIPF/Orig.)The article presents a research and development approach to implement Global Learning in business companies. It shows that there is remarkable interest in Global Learning on the part of international companies if the concept at first is well integrated into the companies´ goals and organization and second is likely to result in economic success. (DIPF/Orig.

Globales Lernen in medial vermittelten Arbeitsgruppen. Kompetenzentwicklung von Führungskräften für globale Zusammenarbeit

Der Beitrag beschreibt die Weiterentwicklung des Anwendungskontexts Globalen Lernens auf den hinsichtlich nachhaltiger Entwicklung besonders kritischen Wirtschaftssektor anhand eines empirischen Projekts im Bereich der Arbeit verteilten, mediengestützten Arbeitsgruppen. Mit Hilfe solcher anwendungsbezogenen Entwicklungen kann die Bildungswissenschaft als Basisdisziplin Globalen Lernens Kontext effizienzorientierter Arbeit verankert und ein Feld beruflicher Professionalisierung erschlossen werden, das bislang brachliegt. (DIPF/Orig.)The article promotes an appropriate advancement of Global Education by applying its context to the business sector, especially crucial with regard to sustainable development by current empirical research and development project in domain of geographically distributed and media supported workgroups. As a result Educational Science can be positioned as a basic profession of Global Education in the up now idle context of efficiency-oriented labour and secondly develop a new field of occupational professionalization. (DIPF/Orig.

Prevalence and influencing factors of sleep disturbances in children just starting school

Ausgehend von der derzeit international als unzureichend einzuschätzenden epidemiologischen Datenlage zu Schlafstörungen bei Vorschul- und Schulkindern wurden im Rahmen der Kölner Kinderschlafstudie die Häufigkeiten von In- und Parasomniebeschwerden und deren Zusammenhang mit Schlafhygenievariablen, physikalischen und gesundheitlichen Belastungsfaktoren sowie komorbid auftretenden Verhaltensauffälligkeiten in einer repräsentativen Kohorte von Schulanfängern der Stadt Köln im Jahr 2002 untersucht. Im Elternurteil finden sich bei den Erstklässlern beachtenswert hohe Prävalenzen für Ein- und/oder Durchschlafstörungen (15%) sowie wiederkehrende Albträume (14%). Die Auftretenshäufigkeiten von Somnambulismus, Pavor nocturnus und Tagesmüdigkeit liegen deutlich darunter. Kinder, die einen stabilen Schlaf-Wach-Rhythmus aufweisen, zeigen gegenüber denen mit unregelmäßigen Aufsteh- und Zubettgehzeiten signifikant seltener Einschlafprobleme und Tagesmüdigkeit. Weiterhin werden wesentliche Zusammenhänge zwischen kindlichen Schlafproblemen und Umgebungsvariablen wie z. B. Licht- und Lärmbelästigung am Schlafplatz dargestellt. Im Hinblick auf die Komorbidität besteht bei den Kindern mit Insomnie- bzw. Parasomniebeschwerden ein zwei- bis dreifach erhöhtes Risiko für Hyperaktivität oder emotionale Probleme. Die Befunde sprechen für die Notwendigkeit einer stärkeren Berücksichtigung der diagnostischen Abklärung von Schlafstörungen und ggf. Interventionsplanung bei psychisch auffälligen und gesunden Kindern.(DIPF/Orig.)Epidemiological studies of sleep disturbances in preschool and school-aged children are underrepresented in international clinical research. Based on this fact we investigated the prevalence of insomnia and parasomnia in a representative sample of school-novices in Cologne in 2002 (Cologne Children’s Sleep Study). We have also considered the relationship between sleep problems on the one hand and sleep hygienic variables, physical and somatic healthy factors and behavioral problems on the other. A high prevalence of insomnia problems (15%) and repeated nightmares (14%) in children of this age were found in parent’s report. Thereas sleepwalking, night terrors and daytime sleepiness were reported less frequently. Children having a solid sleep-wake-schedule show significant less problems to fall into sleep and feel sleepy during the day. Moreover we focused the correlation between disturbed sleep and multiple influencing, as light irritating and noise. We found a two- to three times elevated risk for hyperactive and emotional problems for children with insomnia or parasomnia complaints with regard to the comorbidity of behavioural difficulties. These findings underline the necessity for diagnostic clarifying of sleep disturbances and intervention programs for behavioural disturbed and isolated sleep impaired children.(DIPF/Orig.

Soliton molecules for advanced optical telecommunications

Recent developments in the technology of optical telecommunications are pushed forward by the rapidly growing demand for data-carrying capacity. Current approaches are discussed; most lines of investigation are limited to the linear (i.e. low power) regime. It is shown how this restriction poses a limit for further evolution. If, on the other hand, the nonlinear regime is entered, recent developments about soliton molecules offer a possibility to advance further

A Comparison of Common Breeding Bird Populations in Hamburg, Berlin and Warsaw

The aims of this paper were: 1) to assess the general densities of several species in relation to their habitat in the three cities in order to explain the potential differences in terms of the impact of geographical (East-West gradient) or ecological factors on the avifauna; 2) to test the method of using density relations to conduct these types of comparisons.Avifaunas of three large cities (Hamburg, Berlin and Warsaw) situated in the northern lowlands of Central Europe along an 850-km-long west-east line were compared. Estimates of several species’ breeding populations in these cities were used to calculate their densities in the total area of breeding habitat in each city used by the species in question. The relationship of the densities of several common species was compared. Of 39 species analysed, 18 showed higher densities in Hamburg, 4 in Warsaw and 2 in Berlin. A gradient of increasing density from Warsaw to Berlin and Hamburg (Western gradient) was found for 16 species: Columba palumbus, Troglodytes troglodytes, Prunella modularis, Turdus merula, T. philomelos, T. viscivorus, Sylvia atricapilla, Phylloscopus collybita, Ph. trochilus, Regulus regulus, R. ignicapillus, Garrulus glandarius, Parus cristatus, Certhia brachydactyla, Fringilla coelebs, Pyrrhula pyrrhula. An opposite (Eastern) gradient was found for only 3 species: Columba livia f. domestica, Oriolus oriolus and Passer domesticus. Suggested causes for most of the larger differences among the three cities in the densities of particular species are the variation in the richness of vegetation (higher in both German cities) and differences in the stage of synurbization (i.e. adaptation to the urban environment) of specific avian species. In a few cases, factors such as the geographic range of a species, the attitude of humans (in the case of the Feral Pigeon), and specific, slight variations in habitat are put forward to explain the differences found

Soliton Content of Fiber-Optic Light Pulses

This is a review of fiber-optic soliton propagation and of methods to determine the soliton content in a pulse, group of pulses or a similar structure. Of central importance is the nonlinear Schrödinger equation, an integrable equation that possesses soliton solutions, among others. Several extensions and generalizations of this equation are customary to better approximate real-world systems, but this comes at the expense of losing integrability. Depending on the experimental situation under discussion, a variety of pulse shapes or pulse groups can arise. In each case, the structure will contain one or several solitons plus small amplitude radiation. Direct scattering transform, also known as nonlinear Fourier transform, serves to quantify the soliton content in a given pulse structure, but it relies on integrability. Soliton radiation beat analysis does not suffer from this restriction, but has other limitations. The relative advantages and disadvantages of the methods are compared