Evolution of nonlocal damage in steel under cyclic straining

For high dynamic excitation, e.g. by earthquakes, the vibrations of steel structures lead to inelastic material behavior. Hystereses, developing under cyclic loading, are responsible for the dissipation of energy. Additionally, stress concentration at small defects results in the nucleation and the growth of microvoids which is referred to as damage, here especially as ultra low cycle fatigue. The material damage influences the stiffness of a structure and its response to dynamic excitation. With increasing load the voids can coalesce and form a macrocrack which destroys the structural integrity and peril the overall safety. A material model is proposed which describes the evolution and distribution of inelastic strains and isotropic ductile damage for mild construction steel by means of a set of internal variables. Viscoplasticity as well as isotropic and kinematic hardening are taken into account. The evolution of isotropic hardening is related to the growth of a strain memory surface which accounts for the strain amplitude history of the material. Under tension isotropic ductile damage develops for significant inelastic strains [1]. The material model is implemented in the frameworks of the finite element method with displacement based ansatz functions. The equation of motion is solved with the Newmark method. To overcome the phenomenon of vanishing dissipation energy in case of mesh refinement due to strain localization a nonlocal extension in the form of an implicit gradient formulation is applied. The presented model is used to analyse 3D structures subjected to seismic excitation

Change in population and land use intensity under the aspect of the physical environment and accessibility

The land use in the Tangale-Waja area is analysed according to the two basic categories of geography: Firstly the manifold interaction between men and environment which form the spatial characteristics of an area, and secondly the decrease of influence with increasing distance. The importance of these two elementary factors is described by indicators as accessibility for the period from the precolonial situation until the time after World War II, when new roads were constructed through the mountainous area. Living in a hilly environment the self contained population (formerly called "hill pagans") had developed special agricultural techniques which can be considered ecologically well adapted. The opening up of the area after the pacification, Christianity and education, led to a considerable increase in population, the expansion of land under cultivation, and the change of settlement structure by down-hill population movement. This resulted in overuse of the fragile natural resources. The size of farm steads became too small for the family unit and the still low accessibility of the hinterland of the main interregional roads as well as inappropriate techniques of agricultural production are shortcomings causing heavy damage to the physical environment and decreasing living standards of the local population

PANGAEA information system for glaciological data management

Specific parameters determined on cores from continental ice sheets or glaciers can be used to reconstruct former climate. To use this scientific resource effectively an information system is needed which guarantees consistent longtime storage of data and provides easy access for the scientific community.An information system to archive any data of paleoclimatic relevance, together with the related metadata, raw data and evaluated paleoclimatic data, is presented. The system, based on a relational database, provides standardized import and export routines, easy access with uniform retrieval functions, and tools for the visualization of the data. The network is designed as a client/server system providing access through the Internet with proprietary client software including a high functionality or read-only access on published data via the World Wide Web

Darkness-induced effects on gene expression in Cosmarium crenatum (Zygnematophyceae) from a polar habitat

Light is a key environmental regulator in all photosynthetic organisms. Many studies focused on the physiologic response to changes in light availability of species from the Zygnematophyceae, but the impact of the absence of light and the molecular acclimation process on the other side have been poorly understood. Here we present transcriptomic analyses of Cosmarium crenatum from a polar habitat exposed to darkness. The algae were cultured in dark for one week; cell number and quantum yield of photosystem II (Fv/Fm) were monitored. Cell number was stable, but the Fv/Fm decreased in both groups, darkness-treated and control. Gene expression analysis revealed a strong repression of transcripts associated with photosynthesis, photorespiration and cell wall development. General carbohydrate and lipid metabolism were differentially regulated, but starch is shown to be the primary energy source in these conditions. Additionally, C. crenatum induced mRNA responsible for epigenetic modifications which may be a specific response to an adaption and acclimation to polar conditions. Our study sheds light on the molecular acclimation process to darkness and provides ecological implications for new perspectives in this specialized group of green algae

Адсорбция водорода на чистых и допированных углеродных нанотрубках: DFT моделирование

Рассматривается адсорбция нескольких молекул водорода на внешней и внутренней поверхности комплекса "углеродная нанотрубка (9,9)@Li". Численные эксперименты проводились в пакете SIESTA в двух приближениях для обменно-корреляционного потенциала: приближении обобщенных градиентов (GGA) и приближении локальной электронной плотности (LDA). Моделирование показало, что добавление атома лития позволяет увеличить энергию адсорбции 3-4 молекул водорода (расположенных в первой координационной сфере Li) по сравнению со случаем сорбции на чистой поверхности углеродной нанотрубки. При этом энергии связи попадают в диапазон 200-700 мэВ/(молекулу Н[2]), обеспечивающий эффективность циклов сорбции/десорбции газа, только в случае внутренней сорбции

The parable of the shrewd manager (Lk 16:1–8) : a biography of Jesus and a lesson on mercy

Many scholars have regarded the parable of the shrewd manager (Lk 16:1–8) as the most puzzling of all parables as Jesus seems to use the unrighteous actions of a dishonest (worldly) manager as a model for emulation by others. The unease associated with this understanding was managed in part by focusing almost exclusively on the ‘shrewdness’ of the dishonest manager. In this interpretation, it is not his unjust behaviour that is to be imitated but his wise and intelligent actions. This interpretation has led to a divergence of applications regarding the ‘property’ that was entrusted to him. The author, however, argues that, in the context of the historical Jesus, the entrusted property in the parable references first and foremost the Torah entrusted to God’s people and that the manager mirrors the life of Jesus, who was ‘accused’ by the religious leaders of being unjust. Despite being threatened, he continued unabatedly to scatter God’s mercy, epitomised by the reduction of debt and symbolising the dawning of God’s Kingdom. The manager is therefore not a negative figure but a positive (diaphorical) example of what it means to be a faithful manager of God in the light of adversary and opposition.http://www.hts.org.zaam2013mn201