Nonlinear evolution equations for degenerate transverse waves in anisotropic elastic solids

Transverse elastic waves behave differently in nonlinear isotropic and anisotropic media. Quadratically nonlinear coupling in the evolution equations for wave amplitudes is not possible in isotropic solids, but such a coupling may occur for certain directions in anisotropic materials. We identify the expression responsible for the coupling and we derive coupled canonical evolution equations for transverse wave amplitudes in the case of two-fold and three-fold symmetry acoustic axes. We illustrate our considerations by examples for a cubic crystal.Comment: 4 page

Are Nurses More Altruistic than Real Estate Brokers?

We report results from a dictator game experiment with nurse students and real estate broker students as dictators, and Amnesty International as the recipient. Although brokers contributed substantial amounts, nurses contributed significantly more, on average 76 percent of their endowment. In a second part, subjects chose between a certain repetition of the experiment and a 50-50 chance of costly exit. About one third of the brokers and half of the nurses chose the exit option. While generosity was indeed higher among nurses, even when taking exits into account, the difference cannot readily be attributed to different degrees of altruism.dictator game, exit option, generosity, occupational differences

Risk of Misclassification of decompression sickness

Decompression sickness (DCS) is classified on the basis of which organ system is affected, and neurological DCS is considered more severe than DCS in joints and skin with respect to response to recompression treatment and risk of long-term sequelae. Gas bubble formation interstitially in the tissues or in the circulation is considered to be the mechanism for all types of DCS. Ten patients diagnosed as having DCS in joints or skin, by doctors experienced in diving medicine, underwent clinical examination by a neurologist and had an electroencephalogram. Eight of the ten subjects had findings suggesting central nervous system deficits. The findings indicate that DCS of the central nervous system often accompanies DCS of the joints and skin, and that local skin and joint symptoms may draw attention away from cerebral symptoms. We recommend that all cases with DCS should initially be treated as neurological DCS.publishedVersio

The Finnish Biodiversity Information Facility as a best-practice model for biodiversity data infrastructures

Biodiversity informatics has advanced rapidly with the maturation of major biodiversity data infrastructures (BDDIs), such as the Global Biodiversity Information Facility sharing unprecedented data volumes. Nevertheless, taxonomic, temporal and spatial data coverage remains unsatisfactory. With an increasing data need, the global BDDIs require continuous inflow from local data mobilisation, and national BDDIs are being developed around the world. The global BDDIs are specialised in certain data types or data life cycle stages which, despite possible merits, renders the BDDI landscape fragmented and complex. That this often is repeated at the national level creates counterproductive redundancy, complicates user services, and frustrates funders. Here, we present the Finnish Biodiversity Information Facility (FinBIF) as a model of an all-inclusive BDDI. It integrates relevant data types and phases of the data life cycle, manages them under one IT architecture, and distributes the data through one service portal under one brand. FinBIF has experienced diverse funder engagement and rapid user uptake. Therefore, we suggest the integrated and inclusive approach be adopted in national BDDI development.peerReviewe

Risk of misclassification of decompression sickness

Decompression sickness (DCS) is classified on the basis of which organ system is affected, and neurological DCS is considered more severe than DCS in joints and skin with respect to response to recompression treatment and risk of long-term sequelae. Gas bubble formation interstitially in the tissues or in the circulation is considered to be the mechanism for all types of DCS. Ten patients diagnosed as having DCS in joints or skin, by doctors experienced in diving medicine, underwent clinical examination by a neurologist and had an electroencephalogram. Eight of the ten subjects had findings suggesting central nervous system deficits. The findings indicate that DCS of the central nervous system often accompanies DCS of the joints and skin, and that local skin and joint symptoms may draw attention away from cerebral symptoms. We recommend that all cases with DCS should initially be treated as neurological DCS. (Int Marit Health 2011; 62, 1: 17–19

Demographic developments in Stone Age coastal western Norway by proxy of radiocarbon dates, stray finds and palynological data

This paper presents a multi-proxy approach to coastal Stone Age demography. It uses the district Hordaland, western Norway as a case and applies the proxies SPD (summed probability distributions) of radiocarbon dates and stray find distributions. These are compared to pollen-based landscape reconstructions. Large numbers of Stone Age sites have been surveyed and excavated in western Norway during the last few decades, mainly because of modern development and cultural heritage management. This work has produced significant amounts of radiocarbon dates. The data has, until now, not been sufficiently organized and systematized for the purpose of doing research on long-term changes. The same is true for the many stray finds, which are stored at University Museum of Bergen. During the last decades, methodological development in palynology has made compilation of data and new vegetation reconstructions possible. For the first time, these dispersed datasets from the district Hordaland are brought together for comparative purposes, with a specific goal to study relative demographic changes. The hypothesis is that during the Stone Age, demographic change accompanied big cultural transformations in the transition from LM (late Mesolithic) to EN (early Neolithic) c. 5950 cal BP and between MN (middle Neolithic) and LN (late Neolithic) c. 4300 cal BP. This study partly supports the hypothesis, as the changes in the SPD and the stray finds during the transition to the late Neolithic clearly reflect marked population growth, related to the introduction of agriculture, at the same time as the pollen data reveal forest clearance. The LM-EN transition is less clearly connected to demographic change. Generally, up until the transition to the LN, the data indicate that there was gradual demographic growth with marked fluctuations within a forested landscape. Although the proxies sometimes co-vary for the different periods, they may also display conflicting patterns, and this strengthens the argument that a multi-proxy approach to demographic studies is to be recommended.publishedVersio

Survey of Design Methods and Material Characteristics in Rubber Engineering

The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff structures. Examples of these are shock absorbers, vibration insulators, flexible joints, seals and suspensions.The development of computers and of analysis programs in this area has given engineers a new tool for the design of elastomeric components. Computer simulation by finite element analysis has become increasingly important, allowing the mechanical behavior of products with for complex geometries, as well as loading cases of different kinds to be evaluated. Computer simulations enable both static and dynamic aspects to be analyzed. These matters have been recognized by the manufacturers of rubber products and by their customers. The benefits are shorter time for product development and also quality improvements.However, the possibilities available for finding less complicated technical solutions at lower cost with the use of elastomers, has not been fully utilized. Rubber components could be employed more frequently in design if engineers were more familiar with materials of this sort.Part of the problem lies in education and in the dissemination of information. Engineers working in the design area tend to not be very familiar with elastomeric materials and their properties. The offerings of courses on the mechanics of polymers at schools and universities are very limited. Skillful engineers in this field have usually acquired their knowledge through many years of experience and not formal education.Moreover, the complicated nature of the material behavior involved makes it difficult to devise general design rules and design tools. Only recently have computers and analysis programs become powerful enough for the analysis of nonlinear elastic problems involving large strains.It is essential, if one is to become competitive in high-tech applications, to possess a thorough knowledge of computer methods, material models and test methods available.There has likewise been a lack of relevant data for the computer analysis of elastomeric materials. The design tools employed rely on the material models available and on the test data required for the calibration of these models. In many cases, the only information available for analysis is a value for the hardness of the rubber in question. The wide variety of rubber compounds is also a problem. The characterization of different materials is costly and time-consuming. There is thus a need for simple and reliable methods to characterize the different vulcanizates

Lämpimän ryömintätilaisen alapohjan lämpö- ja kosteustekninen toiminta

publishedVersionNon peer reviewe