Modeling the transport phenomena within arterial wall: porous media approach

The transport of macromolecules, such as low-density lipoprotein (LDL), and their accumulation in the layers of the arterial wall play a critical role in the creation and development of atherosclerosis. Atherosclerosis is a disease of large arteries e.g., the aorta, coronary, carotid, and other proximal arteries that involves a distinctive accumulation of LDL and other lipid-bearing materials in the arterial wall. Over time, plaque hardens and narrows the arteries. The flow of oxygen-rich blood to organs and other parts of the body is reduced. This can lead to serious problems, including heart attack, stroke, or even death. It has been proven that the accumulation of macromolecules in the arterial wall depends not only on the ease with which materials enter the wall, but also on the hindrance to the passage of materials out of the wall posed by underlying layers. Therefore, attention was drawn to the fact that the wall structure of large arteries is different than other vessels which are disease-resistant. Atherosclerosis tends to be localized in regions of curvature and branching in arteries where fluid shear stress (shear rate) and other fluid mechanical characteristics deviate from their normal spatial and temporal distribution patterns in straight vessels. On the other hand, the smooth muscle cells (SMCs) residing in the media layer of the arterial wall respond to mechanical stimuli, such as shear stress. Shear stress may affect SMC proliferation and migration from the media layer to intima. This occurs in atherosclerosis and intimal hyperplasia. The study of blood flow and other body fluids and of heat transport through the arterial wall is one of the advanced applications of porous media in recent years. The arterial wall may be modeled in both macroscopic (as a continuous porous medium) and microscopic scales (as a heterogeneous porous medium). In the present study, the governing equations of mass, heat and momentum transport have been solved for different species and interstitial fluid within the arterial wall by means of computational fluid dynamics (CFD). Simulation models are based on the finite element (FE) and finite volume (FV) methods. The wall structure has been modeled by assuming the wall layers as porous media with different properties. In order to study the heat transport through human tissues, the simulations have been carried out for a non-homogeneous model of porous media. The tissue is composed of blood vessels, cells, and an interstitium. The interstitium consists of interstitial fluid and extracellular fibers. Numerical simulations are performed in a two-dimensional (2D) model to realize the effect of the shape and configuration of the discrete phase on the convective and conductive features of heat transfer, e.g. the interstitium of biological tissues. On the other hand, the governing equations of momentum and mass transport have been solved in the heterogeneous porous media model of the media layer, which has a major role in the transport and accumulation of solutes across the arterial wall. The transport of Adenosine 5´-triphosphate (ATP) is simulated across the media layer as a benchmark to observe how SMCs affect on the species mass transport. In addition, the transport of interstitial fluid has been simulated while the deformation of the media layer (due to high blood pressure) and its constituents such as SMCs are also involved in the model. In this context, the effect of pressure variation on shear stress is investigated over SMCs induced by the interstitial flow both in 2D and three-dimensional (3D) geometries for the media layer. The influence of hypertension (high pressure) on the transport of lowdensity lipoprotein (LDL) through deformable arterial wall layers is also studied. This is due to the pressure-driven convective flow across the arterial wall. The intima and media layers are assumed as homogeneous porous media. The results of the present study reveal that ATP concentration over the surface of SMCs and within the bulk of the media layer is significantly dependent on the distribution of cells. Moreover, the shear stress magnitude and distribution over the SMC surface are affected by transmural pressure and the deformation of the media layer of the aorta wall. This work reflects the fact that the second or even subsequent layers of SMCs may bear shear stresses of the same order of magnitude as the first layer does if cells are arranged in an arbitrary manner. This study has brought new insights into the simulation of the arterial wall, as the previous simplifications have been ignored. The configurations of SMCs used here with elliptic cross sections of SMCs closely resemble the physiological conditions of cells. Moreover, the deformation of SMCs with high transmural pressure which follows the media layer compaction has been studied for the first time. On the other hand, results demonstrate that LDL concentration through the intima and media layers changes significantly as wall layers compress with transmural pressure. It was also noticed that the fraction of leaky junctions across the endothelial cells and the area fraction of fenestral pores over the internal elastic lamina affect the LDL distribution dramatically through the thoracic aorta wall. The simulation techniques introduced in this work can also trigger new ideas for simulating porous media involved in any biomedical, biomechanical, chemical, and environmental engineering applications.

Proposta per a la mobilitat en transport públic : MoveOnApp

This paper wants to show a solution for mobility in public transport. Nowadays, the high number of mobile devices with wireless geolocation and Internet data connection has become commonly used tools, as well as partial solutions to facilitate public transport focused on one means of transport (Bus, Underground ...). We collect information from public transport (means of transport, routes, schedules, fare information ...) and adapt it to different users (residents, visitors, public service staff ...). MoveOnApp is the solution adapting its user interface: finding nearby stops, planning a route, knowing schedules or real time service (connecting to the available services), or showing the route of the line. The system could incorporate new cities and regions, or new means of transport with updating service; at first we offered information of public transport from Palma (Majorca Island, Spain): moveOn Palma.

Trust in inter-organizational relationships

Trust in inter-organizational collaborative relationships has attracted substantial research interest among academics and practitioners. Previous studies have concentrated on the benefits of trust to business outcomes and economic performance, as it is considered to be a source of competitive advantage. Despite this increased level of interest, there is no consensus, much less overall agreement, about how it should be conceptualized or about the number of dimensions it incorporates. On the inter-organizational level there is an obvious challenge in defining both the trusting party and the objects of trust. Thus, the notion of trust as an under-theorized and poorly understood phenomenon still holds. Hence, the motivation of this study was fuelled by the need to increase our knowledge and understanding of the role and nature of trust in inter-organizational collaborative relationships. It is posited that there is a call for more understanding about its antecedents and consequences, as well as about the very concept in inter-organizational collaborative relationships. The study is divided into two parts. The first part gives a general overview, and the second part comprises four research publications. Both qualitative and quantitative research methodology is utilized. A multi-method research design was used because it provides different levels of data and different perspectives on the phenomenon. The results of this study reveal that trust incorporates three dimensions on both the individual and the organizational level: capability, goodwill, and self-reference. Trust develops from the reputation and behavior of the trusted party. It appears from this study that trust is clearly directed towards both individual boundary spanners and the counterpart company itself – i.e. not only to one or the other. The trusting party, on the other hand, is always an individual, and not the organization per se. Trust increases collaboration benefits and lowers collaboration drawbacks, thus having a positive effect on relationship performance. The major contribution of this study lies in uncovering the critical points and drawbacks in prior research and thereby in responding to the highlighted challenges. The way in which these challenges were addressed offers contributions to three major issues in the emerging theory of trust in the inter-organizational context: firstly, this study clarifies the trustor-trustee discussion; secondly, it conceptualizes trust as existing on both individual and organizational levels; and thirdly, it provides more information about the antecedents of trust and the ways in which it affects relationship performance.

Transport, trafik och post

Samlingen med signum HB Xg finns vid huvudbiblioteket och innehåller litteratur om olika transport- och trafikmedel, om sjöfart, om posttrafik etc. till och med år 1999. Vid Sjöhistoriska institutet, Forum Marinum, finns litteratur om sjöfart, se http://www.abo.fi/instut/sjohistoriska/ Litteratur om kommunikationer har ingått i bokdonationer såväl från hemlandet som från Sverige. Friexemplar som erhållits från år 1919 samt inköp har kompletterat samlingen. Litteraturen i samlingen söks i Alma med sökfunktionen Signum och söktermen HB Xg. En del litteratur tryckt före 1980 söks manuellt i den systematiska katalogen, men retroaktiv inmatning i Alma av litteratur tryckt mellan 1830 och 1979 pågår. Från och med år 2000 ingår litteraturen vid huvudbiblioteket om transport, trafik och post i en numerus currens-samling.

A Química Ambiental no Brasil

Defining environmental chemistry is a not an easy task because it encompasses many different topics. According to Stanley E. Manahan, author of a classical textbook of Environmental Chemistry, this branch could be defined as the one centered in the study of the sources, transport, effects and fates of chemical species in the water, soil, and air environments, as well as the influence of human activity upon these processes. More recently, new knowledge emerged from the Environmental Toxicology allowed to go even deeper in the meaning of 'effects' and 'fates' of a continuous growing number of organic and inorganic species disposed in water bodies, soils and atmosphere. Toxicity tests became an important tool to evaluate the environmental impact of such species to a great number of organisms, thus allowing to set quality criteria for drinking water, sediments and biota. The state of art shows that environmental chemistry is a multi-inter disciplinary science by nature; therefore, it needs more than a limited, unique-approach and non-oriented set of data to understand the nature of natural processes. Taking all these aspects into consideration, one can say that Environmental Chemistry in Brazil is now a well established area of research within the classical areas of the Chemistry, with a large number of emerging groups as well research groups with worldwide recognition.

Sevillian transport jars in early colonial America: the case of Santa María La Antigua del Darién (Colombia)

Within the scope of the TECNOLONIAL (HAR2008-02834/HIST) project, an archaeologi- cal and archaeometric research is being conduct- ed in order to clarify and systematize transport jars production in the Iberian peninsula and their distribution abroad, especially to the Americas, from the 15th to the 17th century. The production centre of Seville, in the Crown of Castile, produced large glazed and unglazed transport jars, called botijas, which were mainly devoted to the Atlantic trade network. The pres- ent study accounts for the first results obtained from an initial sample of 34 transport jars dated around the 15th-16th centuries from the produc- tion centre of Seville and the reception site of Santa María de la Antigua del Darién (gulf of Urabá, Colombia). This latter site is especially significant since it was the first Spanish founda- tion (1510) in continental America that obtained the title of town, and was the seat for the Governor of the new region called Castilla de Oro, as well as for the first diocese. All individuals were analyzed by means of x-ray fluorescence and diffraction analyses and then compared with the majolica production database from Seville. The results enabled us to define the first refer- ence groups for such modern transport jars, and to get a first insight into the jars coming to the Americas in the early 16th century whose prove- nance can be linked to Seville, but not Triana.

Use of Biomass Gasification for Transport

This thesis represents an overview of biomass gasification technology together with some practical aspects of this technology application for transport in Finland. The main aim of this work is an assessment whether this technology is perspective in the nearest future for the wide use on transport or not. The first part of the thesis is a kind of survey of the previous works and materials con-cerning the usage of biomass gasification for transport. The second part concentrates more on the practical moments of its use for mobile applications in Finland (taxation, emissions, etc.).

Enhancing the efficiency of freight transport by using simulation

The role of transport in the economy is twofold. As a sector of economic activity it contributes to a share of national income. On the other hand, improvements in transport infrastructure create room for accelerated economic growth. As a means to support railways as a safe and environmentally friendly transportation mode, the EU legislation has required the opening of domestic railway freight for competition from beginning of year 2007. The importance of railways as a mode of transport has been great in Finland, as a larger share of freight has been carried on rails than in Europe on average. In this thesis it is claimed that the efficiency of goods transport can be enhanced by service specific investments. Furthermore, it is stressed that simulation can and should be used to evaluate the cost-efficiency of transport systems on operational level, as well as to assess transportation infrastructure investments. In all the studied cases notable efficiency improvements were found. For example in distribution, home delivery of groceries can be almost twice as cost efficient as the current practice of visiting the store. The majority of the cases concentrated on railway freight. In timber transportation, the item with the largest annual transport volume in domestic railway freight in Finland, the transportation cost could be reduced most substantially. Also in international timber procurement, the utilization of railway wagons could be improved by combining complementary flows. The efficiency improvements also have positive environmental effects; a large part of road transit could be moved to rails annually. If impacts of freight transport are included in cost-benefit analysis of railway investments, up to 50 % increase in the net benefits of the evaluated alternatives can be experienced, avoiding a possible inbuilt bias in the assessment framework, and thus increasing the efficiency of national investments in transportation infrastructure. Transportation systems are a typical example of complex real world systems that cannot be analysed realistically by analytical methods, whereas simulation allows inclusion of dynamics and the level of detail required. Regarding simulation as a viable tool for assessing the efficiency of transportation systems finds support also in the international survey conducted for railway freight operators; operators use operations research methods widely for planning purposes, while simulation is applied only by the larger operators.

Inter organizational learning within and by innovation networks

The thesis deals with the phenomenon of learning between organizations in innovation networks that develop new products, services or processes. Inter organizational learning is studied especially at the level of the network. The role of the network can be seen as twofold: either the network is a context for inter organizational learning, if the learner is something else than the network (organization, group, individual), or the network itself is the learner. Innovations are regarded as a primary source of competitiveness and renewal in organizations. Networking has become increasingly common particularly because of the possibility to extend the resource base of the organization through partnerships and to concentrate on core competencies. Especially in innovation activities, networks provide the possibility to answer the complex needs of the customers faster and to share the costs and risks of the development work. Networked innovation activities are often organized in practice as distributed virtual teams, either within one organization or as cross organizational co operation. The role of technology is considered in the research mainly as an enabling tool for collaboration and learning. Learning has been recognized as one important collaborative process in networks or as a motivation for networking. It is even more important in the innovation context as an enabler of renewal, since the essence of the innovation process is creating new knowledge, processes, products and services. The thesis aims at providing enhanced understanding about the inter organizational learning phenomenon in and by innovation networks, especially concentrating on the network level. The perspectives used in the research are the theoretical viewpoints and concepts, challenges, and solutions for learning. The methods used in the study are literature reviews and empirical research carried out with semi structured interviews analyzed with qualitative content analysis. The empirical research concentrates on two different areas, firstly on the theoretical approaches to learning that are relevant to innovation networks, secondly on learning in virtual innovation teams. As a result, the research identifies insights and implications for learning in innovation networks from several viewpoints on organizational learning. Using multiple perspectives allows drawing a many sided picture of the learning phenomenon that is valuable because of the versatility and complexity of situations and challenges of learning in the context of innovation and networks. The research results also show some of the challenges of learning and possible solutions for supporting especially network level learning.

Magnetic and transport properties of InGaAs quantum wells with Mn

In the present work structural, magnetic and transport properties of InGaAs quantum wells (QW) prepared by MBE with an remote Mn layer are investigated. By means of high-resolution X-ray diffractometry the structure of the samples is analyzed. It is shown that Mn ions penetrate into the QW. Influence of the thickness of GaAs spacer and annealing at 286 ºС on the properties of the system is shown. It is shown that annealing of the samples led to Mn activation and narrowing of the Mn layer. Substantial role of 2D holes in ferromagnetic ordering in Mn layer is shown. Evidence for that is observation of maximum at 25 – 55 K on the resistivity temperature dependence. Position of maximum, which is used for quantitative assessment of the Curie temperature, correlates with calculations of the Curie temperature for structures with indirect interaction via 2D holes’ channel. Dependence of the Curie temperature on the spacer thickness shows, that creation of applicable spintronic devices needs high-precision equipment to manufacture extra fine structures. The magnetotransport measurements show that charge carrier mobility is very low. This leads to deficiency of the anomalous Hall effect. At the same time, magnetic field dependences of the magnetization at different temperatures demonstrate that systems are ferromagnetically ordered. These facts, most probably, give evidence of presence of the ferromagnetic MnAs clusters.

Effect of long-range Coulomb interaction on shot-noise suppression in ballistic transport

We present a microscopic analysis of shot-noise suppression due to long-range Coulomb interaction in semiconductor devices under ballistic transport conditions. An ensemble Monte Carlo simulator self-consistently coupled with a Poisson solver is used for the calculations. A wide range of injection-rate densities leading to different degrees of suppression is investigated. A sharp tendency of noise suppression at increasing injection densities is found to scale with a dimensionless Debye length related to the importance of space-charge effects in the structure.

Energy intensity in road freight transport of heavy goods vehicles in Spain

This paper examines the factors that have influenced the energy intensity of the Spanish road freight transport of heavy goods vehicles over the period 1996–2012. This article aims to contribute to a better understanding of the factors behind the energy intensity change of road freight and also to inform the design of measures to improve energy efficiency in road freight transport. The paper uses both annual single-period and chained multi-period multiplicative LMDI-II decomposition analysis. The results suggest that the decrease in the energy intensity of Spanish road freight in the period is explained by the change in the real energy intensity index (lower energy consumption per tonne-kilometre transported), which is partially offset by the behaviour of the structural index (greater share in freight transport of those commodities the transportation of which is more energy intensive). The change in energy intensity is analysed in more depth by quantifying the contribution of each commodity through the attribution of changes in Divisia indices.

Magnetic and transport properties of II-V diluted magnetic semiconductors doped with manganese and nickel

This thesis is devoted to investigations of three typical representatives of the II-V diluted magnetic semiconductors, Zn1-xMnxAs2, (Zn1-xMnx)3As2 and p-CdSb:Ni. When this work started the family of the II-V semiconductors was presented by only the compounds belonging to the subgroup II3-V2, as (Zn1-xMnx)3As2, whereas the rest of the materials mentioned above were not investigated at all. Pronounced low-field magnetic irreversibility, accompanied with a ferromagnetic transition, are observed in Zn1-xMnxAs2 and (Zn1-xMnx)3As2 near 300 K. These features give evidence for presence of MnAs nanosize magnetic clusters, responsible for frustrated ground magnetic state. In addition, (Zn1-xMnx)3As2 demonstrates large paramagnetic response due to considerable amount of single Mn ions and small antiferromagnetic clusters. Similar paramagnetic system existing in Zn1-xMnxAs2 is much weaker. Distinct low-field magnetic irreversibility, accompanied with a rapid saturation of the magnetization with increasing magnetic field, is observed near the room temperature in p- CdSb:Ni, as well. Such behavior is connected to the frustrated magnetic state, determined by Ni-rich magnetic Ni1-xSbx nanoclusters. Their large non-sphericity and preferable orientations are responsible for strong anisotropy of the coercivity and saturation magnetization of p- CdSb:Ni. Parameters of the Ni1-xSbx nanoclusters are estimated. Low-temperature resistivity of p-CdSb:Ni is governed by a hopping mechanism of charge transfer. The variable-range hopping conductivity, observed in zero magnetic field, demonstrates a tendency of transformation into the nearest-neighbor hopping conductivity in non-zero magnetic filed. The Hall effect in p-CdSb:Ni exhibits presence of a positive normal and a negative anomalous contributions to the Hall resistivity. The normal Hall coefficient is governed mainly by holes activated into the valence band, whereas the anomalous Hall effect, attributable to the Ni1-xSbx nanoclusters with ferromagnetically ordered internal spins, exhibits a low-temperature power-law resistivity scaling.

De nexu inter virtutes intellectuales & morales

Invocatio: Deo moderatore.