Familjära förmaksflimrets karaktär i långtids EKG registrering

Målsättningen med denna studie var att karaktärisera familjära fall av förmaksflimmer (FA) och bestämma förekomsten av fokalt fött FA i detta material. Undersökningsmaterialet bestod av FA patienter på Mejlans rytmkardiologiska klinik, samt familjemedlemmar till dessa. För detta arbete analyserades 24 eller 48 timmars ambulatoriskt EKG på 42 personer. Bland dessa fanns 17 familjer av flera generationer vilka studerades närmare, främst med avseende på förekomsten av fokala triggrar. 40% av FA fallen uppfyllde de uppställda kriterierna för fokalt FA. Denna siffra är signifikant lägre än de ca 80% som tidigare rapporterats vid non-familjärt enskilt FA. Detta kunde tyda på en vid familjärt FA ökad känslighet i förmaken för ändå förekommande men lågfrekventa fokala triggrar. Undersökningen visade att en detaljanalys av 24 timmars Holter registrering är ett användbart sätt att kartlägga förmaksflimrets bakgrund.

Texture and grain-size dependence of tensile properties in warm rolled cadmium

The development of crystallographic texture and the change in the grain size during warm rolling (300 deg K) and their effect on the tensile yield strength at 77 and 300 deg K are studied in 99.9% pure Cd. Both longitudinal and transverse specimens are tested. The yield strength obeys the Hall--Petch relation. The Hall--Petch slope, k, is lower and the intercept sigma o is higher in the warm worked material in comparison with the corresponding values for annealed Cd. The differences are attributed to the change in 1013 < and 0001 textures that are developed during warm rolling.26 refs.--AA

"Kyl mä varmaan kohta ymmärrän." : Asunnon suunnittelu -opetusohjelma oppilaiden ajattelun ja oppimisen haastajana peruskoulun kotitalousopetuksessa

"I will soon understand." The House Planning Program as an Enhancer of Pupils´ Thinking Skills and Learning in Home Economics at Comprehensive School The aim of the research was to build a study program for home economics education in order to enhance pupils´ thinking skills. The program was based on the intervention programs or strategies known as Cognitive Acceleration (CA), which are founded on the theories of Jean Piaget, Lev Vygotsky, and Reuven Feuerstein. In addition, Carl Bereiter s theory of knowledge building was integrated to the research. The viewpoint of home economics was based on the multidimensional foundation of home economics science, particularly household technology and house planning. I first analyzed the kind of body of knowledge home economics science and home economics education provides for enhancing thinking skills in home economics. For the study, a CATE (Cognitive Acceleration through Technology Education) program was adapted and modified and a House Planning program was created for home economics classes. The house planning program consisted of five lessons during which pupils learned how to make functional floor plans as well as choose furniture, household appliances and materials for the home. In order to obtain the required data, various classroom experiments were arranged in 2005 with grade 9 pupils at a comprehensive school in Helsinki. All the experiments were videotaped, and five hours of the videotaped material was edited and transcribed for closer examination. The material consisted of all the video-recorded activity of the selected study group. Interaction study and content analysis were used to analyze the data. Following the experiments, a small survey was conducted to solicit pupils´ and teacher´s opinions of the program. The analysis sheds light on the nature of pupils´ interaction and knowledge building in small group activity. Special attention was given to tracking pupils´ interaction during the socalled construction zone activity. The models and qualities of teacher´s aid and support during the lessons were examined as well. The results revealed the versatility of the pupils social interaction and common knowledge building that occurred during the small group activity. The pupils discussions, including their arguments, their sharing of ideas, and the multiple perspectives that emerged reflected home economics knowledge building. The construction zone activity appeared through expressions of cognitive conflict and metacognition. Cognitive conflict was evident in the pupils´ words and involved questioning, doubting and disputing. The metacognitive activity emerged by thinking aloud, choosing the strategies, and negotiating the results. The pupils also coordinated their activity, allocated the responsibility, and systematized their work. The teacher assisted by preparing new themes for the pupils and by participating in the small group work. The teacher´s help during the small group sessions strengthened the pupils activity in the construction zone. The results showed that one can utilize the wide multidisciplinary basis of home economics, which includes scientific knowledge but also the knowledge derived from practical activity and experience. In this study practical activity was undertaken as a planning project the result of which was a plan or a new vision for the house planning situation. The study showed that the House Planning program was able to enhance the pupils´ social interaction and collaboration. The learning environment challenged the pupils in a way that could be a gateway to further developing their thinking skills. The method of analysis created in the study could be a potential tool for examining social interaction, construction zone activity, and knowledge building in other learning environments as well. Key words: home economics, house planning, classroom experiment, thinking skills,cognitive conflict, metacognition, social interaction, knowledge building

Characteristics of Dynamic Recrystalization Domain in the Processing Map for Hot-Working of OFHC Coper

The constitutive flow behaviour of OFHC copper under working conditions is studied using hot compression in the temperature range 650 to 900-degrees-C and strain rate range 0.001 to 100 s-1. The variation of the efficiency of power dissipation given by [2m/(m + 1)] (where m is the strain rate sensitivity) with temperature and strain rate is represented in the form of a power dissipation map and interpreted on the basis of the Dynamic Materials Model. The map prominently exhibited a domain centered at 850-degrees-C and 100 s-1 with a peak efficiency of 35 %. On the basis of the correlation of variations of grain size, efficiency of power dissipation and hot workability with temperature, the domain is identified to represent dynamic recrystallization (DRX).

Effect of Zirconium on the Processing MAPS For Hot-Working of Alpha-Beta Brass

The effect of zirconium on the hot working characteristics of alpha and alpha-beta brass was studied in the temperature range of 500 to 850-degrees-C and the strain rate range of 0.001 to 100 s-1. On the basis of the flow stress data, processing maps showing the variation of the efficiency of power dissipation (given by [2m/(m+1)] where m is the strain rate sensitivity) with temperature and strain rate were obtained. The addition of zirconium to alpha brass decreased the maximum efficiency of power dissipation from 53 to 39%, increased the strain rate for dynamic recrystallization (DRX) from 0.001 to 0.1 s-1 and improved the hot workability. Alpha-beta brasses with and without zirconium exhibit a domain in the temperature range from 550 to 750-degrees-C and at strain rates lower than 1 s-1 with a maximum efficiency of power dissipation of nearly 50 % occurring in the temperature range of 700 to 750-degrees-C and a strain rate of 0.001 s-1. In the domain, the alpha phase undergoes DRX and controls the hot deformation of the alloy whereas the beta phase deforms superplastically. The addition of zirconium to alpha-beta brass has not affected the processing maps as it gets partitioned to the beta phase and does not alter the constitutive behavior of the alpha phase

Indigenous Knowledge for Biodiversity Conservation

Indigenous peoples with a historical continuity of resource-use practices often possess a broad knowledge base of the behavior of complex ecological systems in their own localities. This knowledge has accumulated through a long series of observations transmitted from generation to generation. Such ''diachronic'' observations can be of great value and complement the ''synchronic''observations on which western science is based. Where indigenous peoples have depended, for long periods of time, on local environments for the provision of a variety of resources, they have developed a stake in conserving, and in some cases, enhancing, biodiversity. They are aware that biological diversity is a crucial factor in generating the ecological services and natural resources on which they depend. Some indigenous groups manipulate the local landscape to augment its heterogeneity, and some have been found to be motivated to restore biodiversity in degraded landscapes. Their practices for the conservation of biodiversity were grounded in a series of rules of thumb which are apparently arrived at through a trial and error process over a long historical time period. This implies that their knowledge base is indefinite and their implementation involves an intimate relationship with the belief system. Such knowledge is difficult for western science to understand. It is vital, however, that the value of the knowledge-practice-belief complex of indigenous peoples relating to conservation of biodiversity is fully recognized if ecosystems and biodiversity are to be managed sustainably. Conserving this knowledge would be most appropriately accomplished through promoting the community-based resource-management systems of indigenous peoples.

The Role of Electronic Word of Mouth in Shaping Consumer Attitudes

The purpose of this research was to investigate the role of electronic word of mouth (eWOM) in shaping consumer attitudes towards various products and services with concentration on the consumer attitude change. eWOM has long been proven to play an important role in influencing consumer attitudes and has been researched from a variety of perspectives. This study attempts to look deeper into the process of consumer attitude change by applying as the central theory of the study the Elaboration Likelihood Model of Persuasion by Petty and Cacioppo. In the processes of examining the background academic and empirical research the Internet and Web 2.0 are closely depicted in order to understand how throughout the past centuries technology allowed the rise of various mediums where consumers can not only share their opinions online about products and services but also communicate with other consumers. Manuel Castel’s Internet Galaxy, Gildin’s, Carl and Noland’s, Hennig-Thurau, Gwinner, Walsh and Gremler’s researches on eWOM are the central works that helped to shape both the theoretical and empirical parts of this study. The mixed method approach was chosen as a research method for this study. An online survey was conducted via the Surveymonkey.com platform and eight qualitative in-depth interviews were conducted. The results of the study show that central route queues as text quality and text argumentativeness are more prominent among the research subjects and the peripheral route queues: source credibility and source expertise did not show considerable significance. Also more experience and participation consumers have with user-rating websites and applications more inclined they are to elaborate on the central route cues and are more likely to search for opinions that they consider rational and credible. Also these respondents are less inclined to search for ratings that confirm their existing beliefs about products or services. Less experience/participation they have about eWOM more likely they are to search for reviews confirmatory to their own.

Hot deformation and microstructural evolution in an alpha(2)/O titanium aluminide alloy Ti-25Al-15Nb

Deformation processing and microstructural development of an alpha(2)/O aluminide alloy Ti-25Al-15Nb (at.%) was studied in the temperature range of 950 to 1200 degrees C and strain rate range of 10(-3) to 100 s(-1). Regions of processing and instability were identified using dynamic materials model. Dynamic recrystallization (DRX) of alpha(2)/O phase and p phase were seen to occur in the region of 950 to 1050 degrees C/0.001 to 0.05 s(-1) and 1125 to 1175 degrees C/0.001 to 0.1 s(-1), respectively. Unstable flow was seen to occur in the region of 1050 to 1190 degrees C/10 to 100 s(-1). Thermal activation analysis showed that DRX of alpha(2)/O and beta was controlled by cross-slip.

Micro and macroscopic features of impact failed defect induced carbon-epoxy composites

Laminated composite structures are susceptible to damage under impacts with attendant properly degradation. While studies on damage tolerance behaviour are emphasised and the findings reported, the citations correlating impacts with the fracture features are limited. In the present study, therefore, attempts have been made to depict how the transition of the fracture features take place depending on the type and extent of defect introduced onto the carbon-epoxy system. The test specimens were subjected to differing levels of low energy pendulum impacts with a view to have specimens with varying levels of intial impacts history. Into such specimens, additional defect in the form of slits of varying depths were introduced by a mechanical process. The test coupons were then allowed to fail by impact. The fracture surface was studied under scanning electron microscope. The fractographic features that appear, based on the induced/inserted defects, are presented in this paper. It was noticed that the energy absorbed for final fracture could be associated with the defect introduced into the system. It was also observed that the size of the mechanically inserted defect had a significant influence on the features of the fracture surface.

Tensile flow behaviour of 2.25Cr-1Mo ferritic steel base metal and simulated heat affected zone structures of 2.25Cr-1Mo weld joint

Tensile tests in the temperature range 298 to 873 K have been performed on 2.25Cr-1Mo base metal and simulated heat affected zone (HAZ) structures of its weld joint, namely coarse grain bainite, fine grain bainite and intercritical structure. Tensile flow behaviour of all the microstructural conditions could be adequately described by the Hollomon equation (sigma = K-1 epsilon(n1)) at higher (> 623 K) temperatures. Deviation from the Hollomon equation was observed at low strains and lower (< 623 K) temperatures. The Ludwigson modification of Hollomon's equation, sigma = K-1 epsilon(n1) + exp (K-2 + n(2) epsilon), was found to describe the flow curve. In general, the flow parameters n(1), K-1, n(2) and K-2 were found to decrease with increase in temperature except in the intermediate temperature range (423 to 623 K). Peaks/plateaus were observed in their variation with temperature in the intermediate temperature range coinciding with the occurrence of serrated flow in the load-elongation curve. The n(1) Value increased and the K-1 value decreased with the type of microstructure in the order: coarse grain bainite, fine grain bainite, base metal and intercritical structure. The variation of nl with microstructure has been rationalized on the basis of mean free path (MFP) of dislocations which is directly related to the inter-particle spacing. Larger MFP of dislocations lead to higher strain hardening exponents n(1).

Thermodynamic properties of the calcium ferrites CaFe2O4 and Ca2Fe2O5

The chemical potentials of CaO in the two-phase fields Fe2O3 + CaFe2O4 and CaFe2O4 + Ca2Fe2O5 of the pseudobinary system CaO - Fe2O3 have been measured in the temperature range from 975 to 1275 K, relative to pure CaO as the reference state, using solid state galvanic cells incorporating single-crystal CaF2 as the solid electrolyte. The cell was operated under pure oxygen at ambient pressure. The standard Gibbs energies of formation of calcium ferrites, CaFe2O4 and Ca2Fe2O5, were derived from the reversible emfs. The results can be summarized by the following equations:CaO + Fe2O3 --> CaFe2O4;Delta G degrees = - 37,480 + 1.16 T (+/- 250) J/mol 2 CaO + Fe2O3 --> Ca2Fe2O5;Delta G degrees = - 45, 280 - 13.51 T (+/- 275) J/mol These values are compared with thermodynamic data reported in the literature. The results of this study are in excellent agreement with heat capacity data, and in reasonable agreement with earlier measurements of enthalpy and Gibbs energy of formation, but suggest significant revision of enthalpies of formation of calcium ferrites given in current thermodynamic compilations.

Kinetic decomposition of Ni2SiO4 in oxygen potential gradients

Nickel orthosilicate (Ni2SiO4) has been found to decompose into its component binary oxides in oxygen potential gradients at 1373 K. Nickel oxide was formed at the high oxygen potential boundary, while silica was detected at the low oxygen potential side. Significant porosity and fissures were observed near the Ni2SiO4/SiO2 interface and the SiO2 layer. The critical oxygen partial pressure ratio required for decomposition varied from 1.63 to 2.15 as the oxygen pressures were altered from 1.01 ⊠ 105 to 2.7X 10−4 Pa, well above the dissociation pressure of Ni2SiO4. Platinum markers placed at the boundaries of the Ni2SiO4 sample indicated growth of NiO at the higher oxygen potential boundary, without any apparent transport of material to the low oxygen potential side. However, significant movement of the bulk Ni2SiO4 crystal with respect to the marker was not observed. The decomposition of the silicate occurs due to the unequal rates of transport of Ni and Si. The critical oxygen partial pressure ratio required for decomposition is related both to the thermodynamic stability of Ni2SiO4 with respect to component oxides and the ratio of diffusivities of nickel and silicon. Kinetic decomposition of multicomponent oxides, first discovered by Schmalzried, Laqua, and co-workers [H. Schmalzried, W. Laqua, and P. L. Lin, Z. Natur Forsch. Teil A 34, 192 (1979); H. Schmalzried and W. Laqua, Oxid. Met. 15, 339 (1981); W. Laqua and H. Schmalzried, Chemical Metallurgy—A Tribute to Carl Wagner (Metallurgical Society of the AIME, New York, 1981), p. 29] has important consequences for their use at high temperatures and in geochemistry.

Influence of homogenization on the processing map for hot working of as-cast Mg-2Zn-1Mn alloy

Processing maps have been developed for hot deformation of Mg-2Zn-1Mn alloy in as-cast condition and after homogenization with a view to evaluate the influence of homogenization. Hot compression data in the temperature range 300-500degreesC and strain rate range 0.001-100 s(-1) were used for generating the processing map. In the map for the as-cast alloy the domain of dynamic recrystallization occurring, at 450degreesC and 0.1 s(-1) has merged with another domain occurring at 500degreesC and 0.001 s(-1) representing grain boundary cracking. The latter domain is eliminated by homogenization and the dynamic recrystallization domain expanded with a higher peak efficiency occurring at 500 degreesC and 0.05 s(-1). The flow localization occurring at strain rates higher than 5 s(-1) is unaffected by homogenization.

Modeling of wheeled mobile robots using dextrous manipulation kinematics

Abstract—This document introduces a new kinematic simulation of a wheeled mobile robot operating on uneven terrain. Our modeling method borrows concepts from dextrous manipulation. This allows for an accurate simulation of the way 3-dimensional wheels roll over a smooth ground surface. The purpose of the simulation is to validate a new concept for design of off-road wheel suspensions, called Passive Variable Camber (PVC). We show that PVC eliminates kinematic slip for an outdoor robot. Both forward and inverse kinematics are discussed and simulation results are presented.