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Search Results: 1 - 10 of 920 matches for " Timo Roine "
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Isotropic non-white matter partial volume effects in constrained spherical deconvolution
Timo Roine,Ben Jeurissen,Daniele Perrone,Alexander Leemans,Jan Sijbers
Frontiers in Neuroinformatics , 2014, DOI: 10.3389/fninf.2014.00028
Abstract: Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35–50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM–GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500–3000 s/mm2, reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.
Lipids of Archaeal Viruses
Elina Roine,Dennis H. Bamford
Archaea , 2012, DOI: 10.1155/2012/384919
Abstract: Archaeal viruses represent one of the least known territory of the viral universe and even less is known about their lipids. Based on the current knowledge, however, it seems that, as in other viruses, archaeal viral lipids are mostly incorporated into membranes that reside either as outer envelopes or membranes inside an icosahedral capsid. Mechanisms for the membrane acquisition seem to be similar to those of viruses infecting other host organisms. There are indications that also some proteins of archaeal viruses are lipid modified. Further studies on the characterization of lipids in archaeal viruses as well as on their role in virion assembly and infectivity require not only highly purified viral material but also, for example, constant evaluation of the adaptability of emerging technologies for their analysis. Biological membranes contain proteins and membranes of archaeal viruses are not an exception. Archaeal viruses as relatively simple systems can be used as excellent tools for studying the lipid protein interactions in archaeal membranes.
Lipids of Archaeal Viruses
Elina Roine,Dennis H. Bamford
Archaea , 2012, DOI: 10.1155/2012/384919
Abstract: Archaeal viruses represent one of the least known territory of the viral universe and even less is known about their lipids. Based on the current knowledge, however, it seems that, as in other viruses, archaeal viral lipids are mostly incorporated into membranes that reside either as outer envelopes or membranes inside an icosahedral capsid. Mechanisms for the membrane acquisition seem to be similar to those of viruses infecting other host organisms. There are indications that also some proteins of archaeal viruses are lipid modified. Further studies on the characterization of lipids in archaeal viruses as well as on their role in virion assembly and infectivity require not only highly purified viral material but also, for example, constant evaluation of the adaptability of emerging technologies for their analysis. Biological membranes contain proteins and membranes of archaeal viruses are not an exception. Archaeal viruses as relatively simple systems can be used as excellent tools for studying the lipid protein interactions in archaeal membranes. 1. Introduction Viruses are obligate parasites. Their hallmark is the virion, an infectious particle made of proteins and encapsidating the viral genome. Many viruses, however, also contain lipids as essential components of the virion [1]. The majority of viral lipids are found in membranes, but viral proteins can also be modified with lipids [2, 3]. 1.1. Membrane Containing Viruses in the Viral Universe Membrane containing viruses can roughly be divided into two subclasses [1]. The first subclass contains viruses in which the membrane, also called an envelope, is the outermost layer of the viral particle. In the second class of viruses, the membrane is underneath the usually icosahedral protein capsid. Few viruses contain both the inner membrane as well as an envelope [1]. Lipid membranes of viruses have evolved into essential components of virions that in many cases seem to be involved in the initial stages of infection [4–6]. The majority of membrane containing viruses infect animals both vertebrate and invertebrate that do not have a cell wall surrounding the cytoplasmic membrane. For other host organisms such as plants and prokaryotes there are much fewer membrane containing viruses known [1]. Usually the cells of these organisms are covered with a cell wall. By far the majority of known viruses that infect prokaryotes, that is, bacteria (bacteriophages), and archaea (archaeal viruses) belong to the order Caudovirales, the tailed viruses (Figure 1) [1, 7]. These viruses are made of the icosahedrally
Clustering and inertia: structural integration of home care in Swedish elderly care
Nils Olof Hedman,Roine Johansson,Urban Rosenqvist
International Journal of Integrated Care , 2007,
Abstract: Purpose: To study the design and distribution of different organizational solutions regarding the responsibility for and provision of home care for elderly in Swedish municipalities. Method: Directors of the social welfare services in all Swedish municipalities received a questionnaire about old-age care organization, especially home care services and related activities. Rate of response was 73% (211/289). Results: Three different organizational models of home care were identified. The models represented different degrees of integration of home care, i.e. health and social aspects of home care were to varying degrees integrated in the same organization. The county councils (i.e. large sub-national political-administrative units) tended to contain clusters of municipalities (smaller sub-national units) with the same organizational characteristics. Thus, municipalities' home care organization followed a county council pattern. In spite of a general tendency for Swedish municipalities to reorganize their activities, only 1% of them had changed their home care services organization in relation to the county council since the reform. Conclusion: The decentralist intention of the reform—to give actors at the sub-national levels freedom to integrate home care according to varying local circumstances—has resulted in a sub-national inter-organizational network structure at the county council, rather than municipal, level, which is highly inert and difficult to change.
Measured and Perceived Physical Fitness, Intention, and Self-Reported Physical Activity in Adolescence  [PDF]
Timo Jaakkola, Tracy Washington
Advances in Physical Education (APE) , 2011, DOI: 10.4236/ape.2011.12004
Abstract: Objective: The aim of this study was to investigate the associations among measured physical fitness, perceived fitness, intention towards future physical activity and self-reported physical activity through junior high school years. Methods: Study participants included 122 Finnish students who were 13 years old during Grade 7. The sample was comprised of 80 girls and 42 boys from 3 junior high schools (Grades 7-9). During the autumn semester of Grade 7, students completed fitness tests and a questionnaire analyzing self-perception of their physical fitness. The questionnaire delivered at Grade 8 included intention towards future physical activity. At Grade 9 students’ self-reported physical activity levels. Results: Structural Equation Modelling revealed an indirect path from physical fitness to self-reported physical activity via perceived physical fitness and intention towards future physical activity. The model also demonstrated a correlation between perceived physical fitness and physical activity. Squared multiple correlations revealed that perceived physical fitness explained 33 % of the actual physical fitness. Conclusions: The results of this study highlight the role of physical and cognitive variables in the process of adoption of physical activity in adolescence.
Use of Augmented Reality Methods to Support Legal Conflicts in the Planning Process for Wind Turbines Using the Example of the Landscape Conservation Area “Eulenkopf and Surroundings”  [PDF]
Timo Wundsam, Sascha M. Henninger
Energy and Power Engineering (EPE) , 2014, DOI: 10.4236/epe.2014.611030
Abstract: The world’s growing energy demand poses a serious problem. At the same time fossil fuels are finite, which we must work against. Therefore, the Federal Government of Germany has set itself the goal to push forward the use of renewable energy in order to completely do without the generation of nuclear energy by 2023. There are, however, no specific guidelines from the European Directive on the promotion of electricity from renewable energy sources for the internal electricity market regarding how high each share of the different production method should be and, above all, which specific aim should be achieved by the share of wind energy. Nevertheless, it presents a crucial step toward a nuclear phaseout and a concomitant change of course of the Federal Government of Germany in the spring of 2011 regarding the expansion of renewable energy, taking the nuclear catastrophe in Fukushima into account. Using new legal planning approaches, also including the area of Rhineland-Palatinate, opportunities should be provided to make previously protected land available for setting up facilities for the generation of renewable energy. However, it is important to examine the legal situation regarding the installation of these kinds of constructions more detailed, as no general statements can be made. This will be illustrated using the example of the landscape conservation area “Eulenkopf and surrounding area” in the district of Kaiserslautern. The stated goal of the Social Democrat/Green coalition of the federal state government of Rhineland-Palatinate is to considerably expand the generation of electricity from renewable energy sources so that by 2030 at least the entire electricity demand can be covered by those. Due to the enormous potential of wind power, it is therefore necessary to quintuple its share of electricity generation by 2020, compared to 2011 numbers. In order to achieve the desired political objectives, by 2030 the number of turbines has to be increased to around 2650, representing a capacity of 7500 MW. This increase gives reason for boundary conditions to manage the generation of wind energy to be adjusted. This is intended to facilitate management and simultaneously minimise negative effects, such as the “sprawling” of wind turbines.
Synaptic Plasticity and Learning in Animal Models of Tuberous Sclerosis Complex
Timo Kirschstein
Neural Plasticity , 2012, DOI: 10.1155/2012/279834
Abstract: Tuberous sclerosis complex (TSC) is caused by a mutation of either the Tsc1 or Tsc2 gene. As these genes work in concert to negatively regulate the mammalian target of rapamycin (mTOR) kinase which is involved in protein translation, mutations of these genes lead to a disinhibited mTOR activity. Both the clinical appearance of this condition including tumors, cognitive decline, and epileptic seizures and the molecular understanding of the mTOR signaling pathway, not only involved in cell growth, but also in neuronal functioning, have inspired numerous studies on learning behavior as well as on synaptic plasticity which is the key molecular mechanism of information storage in the brain. A couple of interesting animal models have been established, and the data obtained in these animals will be discussed. A special focus will be laid on differences among these models, which may be in part due to different background strains, but also may indicate pathophysiological variation in different mutations. 1. Introduction Tuberous sclerosis complex (TSC) is an inherited disease caused by a heterozygous germ line mutation of either the Tsc1 or Tsc2 gene that is manifested in early childhood. The pathological hallmark of this disorder is the development of hamartomas (benign tumors) arising in a number of organs including the central nervous system [1, 2]. In the brain, TSC lesions typically comprise of cortical tubers, subependymal nodules, and giant cell astrocytomas [3, 4].Hence, common symptoms related to brain lesions are epileptic seizures, mental retardation, multiple neuropsychological impairments, and even autism [5–9]. Consequently, the significant neuropsychiatric morbidity caused by this condition has inspired a number of groups worldwide to study the underlying pathomechanisms aiming to improve our functional understanding of both gene products, named hamartin (Tsc1) and tuberin (Tsc2). These proteins act in concert as a guanosine triphosphate-activating protein (GAP) towards the small G protein Rheb, which is the key regulator of the mammalian target of rapamycin (mTOR) signaling [10, 11]. Since hamartin and tuberin negatively regulate mTOR activity, which in turn phosphorylates and thereby activates important translation factors such as p70 S6 kinase 1 (S6K1) and eukaryote initiation factor 4E-binding protein (eIF4E-BP), a major role of the TSC-mTOR signaling pathway has been suggested for tumorigenesis, and both genes were initially recognized as tumor suppressors [12]. However, increasing evidence has been provided that this pathway is also
A mechanistic model of infection: why duration and intensity of contacts should be included in models of disease spread
Timo Smieszek
Theoretical Biology and Medical Modelling , 2009, DOI: 10.1186/1742-4682-6-25
Abstract: We present an exposure-based, mechanistic model of disease transmission that reflects heterogeneities in contact duration and intensity. Based on empirical contact data, we calculate the expected number of secondary cases induced by an infector (i) for the mechanistic model and (ii) under the classical assumption of a constant per-contact transmission probability. The results of both approaches are compared for different basic reproduction numbers R0.The outcomes of the mechanistic model differ significantly from those of the assumption of a constant per-contact transmission probability. In particular, cases with many different contacts have much lower expected numbers of secondary cases when using the mechanistic model instead of the common assumption. This is due to the fact that the proportion of long, intensive contacts decreases in the contact dataset with an increasing total number of contacts.The importance of highly connected individuals, so-called super-spreaders, for disease spread seems to be overestimated when a constant per-contact transmission probability is assumed. This holds particularly for diseases with low basic reproduction numbers. Simulations of disease spread should weight contacts by duration and intensity.Research has shown that the arrangement of potentially contagious contacts among the individuals of a society is a determining factor of disease spread: Both the repetition and the clustering of contacts diminish the size of an outbreak compared to a random mixing model [1-3]. Further, the epidemic threshold is low if the degree distribution shows a high dispersion [4,5]. In contrast to the vast body of literature that exists on the importance of network structure, only little emphasis has been put on the quality of such potentially contagious contacts, i.e. how long they last and how intensive they are. In fact, mathematical models and computer simulations of disease propagation often assume a constant per-contact transmission probability
Dealing with Ecological Objectives in the Monsu Planning System
Pukkala,Timo;
Silva Lusitana , 2004,
Abstract: the article describes some approaches to incorporate ecological objectives into numerical forest planning when using the monsu software. monsu first simulates alternative treatment schedules for all stands in the planning area, over a user-specified planning horizon. it then seeks the best combination of stands' treatment schedules using numerical optimisation. management objectives are included in the optimisation model either as objective variables or constraints. the ecological variables that monsu can calculate - and which can therefore be considered in optimisation - include (1) ordinary but ecologically oriented forest characteristics such as deadwood volume and area of old forest, (2) a special biodiversity score calculated for the forest, and (3) a set of landscape metrics. landscape metrics are variables that measure the sizes, shapes, relative arrangement and connectivity of habitat patches as well as their total area. the most recent development of monsu has concentrated on the use of landscape metrics, which measure the forest?s ecological quality at the landscape level. a proper scale of ecological planning depends on the size of the territory of the species considered, and it seems that most of the keynote species have rather large territories and therefore require forest rather than stand level evaluations of ecological quality.
Usage and Impact of Controlled Vocabularies in a Subject Repository for Indexing and Retrieval
Timo Borst
Liber Quarterly : The Journal of European Research Libraries , 2012,
Abstract: Since 2009, the German National Library for Economics (ZBW) supports both indexing and retrieval of Open Access scientific publications like working papers, postprint articles and conference papers by means of a terminology web service. This web service is based on concepts organized as a ‘Standard Thesaurus for Economics’ (STW), which is modelled and regularly published as Linked Open Data. Moreover, it is integrated into the institution’s subject repository for automatically suggesting appropriate key words while indexing and retrieving documents, and for automatically expanding search queries on demand to gain better search results. While this approach looks promising to augment ‘off the shelf’ repository software systems in a lightweight manner with a disciplinary profile, there is still significant uncertainty about the effective usage and impact of controlled terms in the realm of these systems. To cope with this, we analyze the repository’s logfiles to get evidence of search behaviour which is potentially influenced by auto suggestion and expansion of scientific terms derived from a discipline’s literature.
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