Anthropomorphic model observer performance in three-dimensional detection task for low-contrast computed tomography.

X-ray medical imaging is increasingly becoming three-dimensional (3-D). The dose to the population and its management are of special concern in computed tomography (CT). Task-based methods with model observers to assess the dose-image quality trade-off are promising tools, but they still need to be validated for real volumetric images. The purpose of the present work is to evaluate anthropomorphic model observers in 3-D detection tasks for low-contrast CT images. We scanned a low-contrast phantom containing four types of signals at three dose levels and used two reconstruction algorithms. We implemented a multislice model observer based on the channelized Hotelling observer (msCHO) with anthropomorphic channels and investigated different internal noise methods. We found a good correlation for all tested model observers. These results suggest that the msCHO can be used as a relevant task-based method to evaluate low-contrast detection for CT and optimize scan protocols to lower dose in an efficient way.

A feed-forward spiking model of shape-coding by IT cells

The ability to recognize a shape is linked to figure-ground (FG) organization. Cell preferences appear to be correlated across contrast-polarity reversals and mirror reversals of polygon displays, but not so much across FG reversals. Here we present a network structure which explains both shape-coding by simulated IT cells and suppression of responses to FG reversed stimuli. In our model FG segregation is achieved before shape discrimination, which is itself evidenced by the difference in spiking onsets of a pair of output cells. The studied example also includes feature extraction and illustrates a classification of binary images depending on the dominance of vertical or horizontal borders.

Cue-dependent circuits for illusory contours in humans.

NlmCategory="UNASSIGNED">Objects' borders are readily perceived despite absent contrast gradients, e.g. due to poor lighting or occlusion. In humans, a visual evoked potential (VEP) correlate of illusory contour (IC) sensitivity, the "IC effect", has been identified with an onset at ~90ms and generators within bilateral lateral occipital cortices (LOC). The IC effect is observed across a wide range of stimulus parameters, though until now it always involved high-contrast achromatic stimuli. Whether IC perception and its brain mechanisms differ as a function of the type of stimulus cue remains unknown. Resolving such will provide insights on whether there is a unique or multiple solutions to how the brain binds together spatially fractionated information into a cohesive perception. Here, participants discriminated IC from no-contour (NC) control stimuli that were either comprised of low-contrast achromatic stimuli or instead isoluminant chromatic contrast stimuli (presumably biasing processing to the magnocellular and parvocellular pathways, respectively) on separate blocks of trials. Behavioural analyses revealed that ICs were readily perceived independently of the stimulus cue-i.e. when defined by either chromatic or luminance contrast. VEPs were analysed within an electrical neuroimaging framework and revealed a generally similar timing of IC effects across both stimulus contrasts (i.e. at ~90ms). Additionally, an overall phase shift of the VEP on the order of ~30ms was consistently observed in response to chromatic vs. luminance contrast independently of the presence/absence of ICs. Critically, topographic differences in the IC effect were observed over the ~110-160ms period; different configurations of intracranial sources contributed to IC sensitivity as a function of stimulus contrast. Distributed source estimations localized these differences to LOC as well as V1/V2. The present data expand current models by demonstrating the existence of multiple, cue-dependent circuits in the brain for generating perceptions of illusory contours.

Understanding oceanic migrations with intrinsic biogeochemical markers

Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment.

Comparative dosimetry in intracavitary balloon catheter brachytherapy with I-125 and in Cf-252 brachytherapy combined with BNCT for brain tumors

Objective Comparative analysis of dosimetry in intracavitary balloon catheter brachytherapy with I-125 and in Cf-252 brachytherapy combined with BNCT for treatment of brain tumors. Materials and Methods Simulations of intracavitary balloon catheter brachytherapy with I-125 and in Cf-252 brachytherapy combined with BNCT were performed with the MCNP5 code, modeling the treatment of a brain tumor on a voxel computational phantom representing a human head. Absorbed dose rates were converted into biologically weighted dose rates. Results Intracavitary balloon catheter brachytherapy with I-125 produced biologically weighted mean dose rates of 3.2E-11, 1.3E-10, 1.9E-11 and 6.9E-13 RBE.Gy.h-1.p-1.s, respectively, on the healthy tissue, on the balloon periphery and on the I 1 and I 2 tumor infiltration zones. On the other hand, Cf-252 brachytherapy combined with BNCT produced a biologically weighted mean dose rate of 5.2E-09, 2.3E-07, 8.7E-09 and 2.4E-09 RBE.Gy.h-1.p-1.s, respectively on the healthy tissue, on the target tumor and on the I 1 and I 2 infiltration zones. Conclusion Cf-252 brachytherapy combined with BNCT delivered a selective irradiation to the target tumor and to infiltration zones, while intracavitary balloon catheter brachytherapy with I-125 delivered negligible doses on the tumor infiltration zones.

Trasporti e sviluppo territoriale negli spazi intermedi : l'esempio della regione transfrontaliera Insubrica

Avec cette thèse de doctorat nous proposons une réflexion transversale concernant les relations entre infrastructures de transport et développement territorial dans des espaces dits « intermédiaires ». Le concept d'espace intermédiaire, relativement nouveau en géographie, est conçu en fonction d'une double approche : celle des infrastructures où les espaces intermédiaires constituent des zones de transit obligées entre des pôles urbains hiérarchiquement supérieurs (par rapport une échelle horizontale) et celle des frontières où les espaces intermédiaires constituent des territoires de coopération entre différents niveaux politico-institutionnels (par rapport à une échelle verticale). Cette problématique de recherche est traitée aussi bien du point de vue théorique qu'avec des études de cas portant sur les effets des nouvelles infrastructures de transports dans la région transfrontalière insubrique (entre le Canton du Tessin et la Lombardie). L'objectif visé est de défendre un scénario d'organisation spatiale polycentrique à plusieurs niveaux comme solution pour le développement durable et cohérent de ces espaces intermédiaires. Ainsi, pour le « niveau macro », nous proposons une analyse des changements d'accessibilité spatiale et des potentiels de développement territorial pour les agglomérations concernées par la mise en service du nouveau tunnel ferroviaire de base du Monte Ceneri (TBC) et de la nouvelle ligne Lugano/Como-Mendrisio-Varese-Malpensa (FMV) à l'horizon 2020. Pour le « niveau meso », nous analysons les effets de la nouvelle ligne FMV en termes de potentiel de densification polycentrique autours des gares ferroviaires. Pour le « niveau micro », nous proposons une analyse sur les comportements de mobilité ainsi que des améliorations ciblées du système de transport pour la ville de Mendrisio visant à promouvoir le développement polycentrique de cette commune. De plus, un système d'analyse permettant de mettre en lien les divers facteurs explicatifs dans l'analyse des relations entre les nouvelles infrastructures de transport et les effets sur la mobilité et le développement territorial est également élaboré et testé dans notre recherche. -- With this Ph.D. thesis we investigate the relationship between transport infrastructures and territory development inside the so called "in-between spaces". The idea of "in-between space", relatively novel in geography, is the formal outcome of a double approach: the one of the infrastructures, saying that these spaces can be described as areas of constrained transit between urban centres of superior hierarchical level (on a horizontal scale), and the one of the borders, stating that in-between spaces are areas of cooperation between various political-institutional levels. The above mentioned research issues are deepened both at theoretical and empirical level, being the latter based on field studies of the cross-boundary Western-Lombard area (between the Swiss canton of Ticino and the Italian region of Lombardy). This research pursues the goal of defending the argument that a multi-level polycentric spatial scenario can be a possible solution fora sustainable development of the above described in- between areas. From a "macro" perspective, what we submit here is an analysis on the expected changes in spatial accessibility and on the potential territorial development for the built-up areas influenced by the construction of the new train tunnel of the Monte Ceneri (TBC) and of the new railway line Lugano/Como-Mendrisio-Varese-Malpensa (FMV). At a "meso" level we analyse the effects exerted by the new FMV line taking into account the potential densification of the areas surrounding the railway stations. Finally, at a "micro" level, we analyse the mobility behaviours in the town of Mendrisio and we propose some possible improvements to the local public transport system, with the scope to promote a polycentric development of this municipality. Moreover, we developed and tested an analytic system able to define the existing links between the various explaining factors characterizing the relationship between new transport infrastructures and effects on mobility. -- With this Ph.D. thesis we investigate the relationship between transport infrastructures and territory development inside the so called "in-between spaces". The idea of "in-between space", relatively novel in geography, is the formal outcome of a double approach: the one of the infrastructures, saying that these spaces can be described as areas of constrained transit between urban centres of superior hierarchical level (on a horizontal scale), and the one of the borders, stating that in-between spaces are areas of cooperation between various political-institutional levels. The above mentioned research issues are deepened both at theoretical and empirical level, being the latter based on field studies of the cross-boundary Western-Lombard area (between the Swiss canton of Ticino and the Italian region of Lombardy). This research pursues the goal of defending the argument that a multi-level polycentric spatial scenario can be a possible solution for a sustainable development of the above described in- between areas. From a "macro" perspective, what we submit here is an analysis on the expected changes in spatial accessibility and on the potential territorial development for the built-up areas influenced by the construction of the new train tunnel of the Monte Ceneri (TBC) and of the new railway line Lugano/Como-Mendrisio-Varese-Malpensa (FMV). At a "meso" level we analyse the effects exerted by the new FMV line taking into account the potential densification of the areas surrounding the railway stations. Finally, at a "micro" level, we analyse the mobility behaviours in the town of Mendrisio and we propose some possible improvements to the local public transport system, with the scope to promote a polycentric development of this municipality. Moreover, we developed and tested an analytic system able to define the existing links between the various explaining factors characterizing the relationship between new transport infrastructures and effects on mobility.

Development and validation of a visual grading scale for assessing image quality of AP pelvis radiographic images.

OBJECTIVE: The aim of this article was to apply psychometric theory to develop and validate a visual grading scale for assessing the visual perception of digital image quality anteroposterior (AP) pelvis. METHODS: Psychometric theory was used to guide scale development. Seven phantom and seven cadaver images of visually and objectively predetermined quality were used to help assess scale reliability and validity. 151 volunteers scored phantom images, and 184 volunteers scored cadaver images. Factor analysis and Cronbach's alpha were used to assess scale validity and reliability. RESULTS: A 24-item scale was produced. Aggregated mean volunteer scores for each image correlated with the rank order of the visually and objectively predetermined image qualities. Scale items had good interitem correlation (≥0.2) and high factor loadings (≥0.3). Cronbach's alpha (reliability) revealed that the scale has acceptable levels of internal reliability for both phantom and cadaver images (α = 0.8 and 0.9, respectively). Factor analysis suggested that the scale is multidimensional (assessing multiple quality themes). CONCLUSION: This study represents the first full development and validation of a visual image quality scale using psychometric theory. It is likely that this scale will have clinical, training and research applications. ADVANCES IN KNOWLEDGE: This article presents data to create and validate visual grading scales for radiographic examinations. The visual grading scale, for AP pelvis examinations, can act as a validated tool for future research, teaching and clinical evaluations of image quality.

CHARACTERISING THE EOS SLOT-SCANNING SYSTEM WITH THE EFFECTIVE DETECTIVE QUANTUM EFFICIENCY.

NlmCategory="UNASSIGNED">As opposed to the standard detective quantum efficiency (DQE), effective DQE (eDQE) is a figure of merit that allows comparing the performances of imaging systems in the presence of scatter rejection devices. The geometry of the EOS™ slot-scanning system is such that the detector is self-collimated and rejects scattered radiation. In this study, the EOS system was characterised using the eDQE in imaging conditions similar to those used in clinical practice: with phantoms of different widths placed in the X-ray beam, for various incident air kerma and tube voltages corresponding to the phantom thickness. Scatter fractions in EOS images were extremely low, around 2 % for all configurations. Maximum eDQE values spanned 9-14.8 % for a large range of air kerma at the detector plane from 0.01 to 1.34 µGy. These figures were obtained with non-optimised EOS setting but still over-performed most of the maximum eDQEs recently assessed for various computed radiology and digital radiology systems with antiscatter grids.

From Regional Landslide Detection to Site-Specific Slope Deformation Monitoring and Modelling Based on Active Remote Sensors

Landslide processes can have direct and indirect consequences affecting human lives and activities. In order to improve landslide risk management procedures, this PhD thesis aims to investigate capabilities of active LiDAR and RaDAR sensors for landslides detection and characterization at regional scales, spatial risk assessment over large areas and slope instabilities monitoring and modelling at site-specific scales. At regional scales, we first demonstrated recent boat-based mobile LiDAR capabilities to model topography of the Normand coastal cliffs. By comparing annual acquisitions, we validated as well our approach to detect surface changes and thus map rock collapses, landslides and toe erosions affecting the shoreline at a county scale. Then, we applied a spaceborne InSAR approach to detect large slope instabilities in Argentina. Based on both phase and amplitude RaDAR signals, we extracted decisive information to detect, characterize and monitor two unknown extremely slow landslides, and to quantify water level variations of an involved close dam reservoir. Finally, advanced investigations on fragmental rockfall risk assessment were conducted along roads of the Val de Bagnes, by improving approaches of the Slope Angle Distribution and the FlowR software. Therefore, both rock-mass-failure susceptibilities and relative frequencies of block propagations were assessed and rockfall hazard and risk maps could be established at the valley scale. At slope-specific scales, in the Swiss Alps, we first integrated ground-based InSAR and terrestrial LiDAR acquisitions to map, monitor and model the Perraire rock slope deformation. By interpreting both methods individually and originally integrated as well, we therefore delimited the rockslide borders, computed volumes and highlighted non-uniform translational displacements along a wedge failure surface. Finally, we studied specific requirements and practical issues experimented on early warning systems of some of the most studied landslides worldwide. As a result, we highlighted valuable key recommendations to design new reliable systems; in addition, we also underlined conceptual issues that must be solved to improve current procedures. To sum up, the diversity of experimented situations brought an extensive experience that revealed the potential and limitations of both methods and highlighted as well the necessity of their complementary and integrated uses.

Anticorpos catalíticos: expandindo o alcance da catálise enzimática

The vast binding repertoire of the immune system has been exploited for the generation of tailor-made selective catalysts. Since the first reports of chemical reactions catalyzed by antibodies were published, research in this field, which borders chemistry and biology, has been rapidly established and a number of catalytic antibodies that carry out a wide range of reactions, have been developed. Recent advances have led to antibodies that catalyse complex, multi-step reactions and difficult chemical transformations, as well as reactions that do not have an organic equivalent at all. Current research in this field has been devoted to practical applications of this technology.

A missing spatial link in institutional quality

History tells that institutions evolve gradually over time, pushing new ideas across borders and cultures. Globalisation is argued to accelerate this process. We examine the spatial links of different political institutions across borders. Applying various tests for spatial proximity, we do not find evidence of contemporaneous spatial links. This result is robust to various measures of distance and of cultural proximity across countries. Instead, when we analyse long run dynamics diffusion of institutions seems to occur only gradually.

Performance and Methodological Aspects in Positron Emission Tomography

Performance standards for Positron emission tomography (PET) were developed to be able to compare systems from different generations and manufacturers. This resulted in the NEMA methodology in North America and the IEC in Europe. In practices, the NEMA NU 2- 2001 is the method of choice today. These standardized methods allow assessment of the physical performance of new commercial dedicated PET/CT tomographs. The point spread in image formation is one of the factors that blur the image. The phenomenon is often called the partial volume effect. Several methods for correcting for partial volume are under research but no real agreement exists on how to solve it. The influence of the effect varies in different clinical settings and it is likely that new methods are needed to solve this problem. Most of the clinical PET work is done in the field of oncology. The whole body PET combined with a CT is the standard investigation today in oncology. Despite the progress in PET imaging technique visualization, especially quantification of small lesions is a challenge. In addition to partial volume, the movement of the object is a significant source of error. The main causes of movement are respiratory and cardiac motions. Most of the new commercial scanners are in addition to cardiac gating, also capable of respiratory gating and this technique has been used in patients with cancer of the thoracic region and patients being studied for the planning of radiation therapy. For routine cardiac applications such as assessment of viability and perfusion only cardiac gating has been used. However, the new targets such as plaque or molecular imaging of new therapies require better control of the cardiac motion also caused by respiratory motion. To overcome these problems in cardiac work, a dual gating approach has been proposed. In this study we investigated the physical performance of a new whole body PET/CT scanner with NEMA standard, compared methods for partial volume correction in PET studies of the brain and developed and tested a new robust method for dual cardiac-respiratory gated PET with phantom, animal and human data. Results from performance measurements showed the feasibility of the new scanner design in 2D and 3D whole body studies. Partial volume was corrected, but there is no best method among those tested as the correction also depends on the radiotracer and its distribution. New methods need to be developed for proper correction. The dual gating algorithm generated is shown to handle dual-gated data, preserving quantification and clearly eliminating the majority of contraction and respiration movement

Fiscal policy and interest rates: the role of financial and economic integration

It is commonly believed that a fiscal expansion raises interest rates. However, these crowding out effects of deficits have been found to be small or non-existent. One explanation is that financial integration offsets interest rate differentials on globalised bond markets. This paper measures the degree of integration of government bond markets, using spatial modelling techniques to take this spillover on financial markets into account. Our main finding is that the crowding out effect on domestic interest rates is significant, but is reduced by spillover across borders. This spillover is important in major crises or in periods of coordinated policy actions. This result is generally robust to various measures of cross-country linkages. We find spillover to be much stronger among EU countries.

Internet Banking in Europe: a comparative analysis

A key strategic issue for banks is the implementation of internet banking. The ‘click and mortar’ model that complements classical branch banking with online facilities is competing with pure internet banks. The objective of this paper is to compare the performance of these two models across countries, so as to examine the role of differences in the banking system and technological progress. A fuzzy cluster analysis on the performance of banks in Finland, Spain, Italy and the UK shows that internet banks are hard to distinguish from banks that follow a click and mortar strategy; country borders are more important. We therefore explain bank performance by a group of selected bank features, country-specific economic and IT indicators over the period 1995-2004. We find that the strategy of banking groups to incorporate internet banks reflects some competitive edge that these banks have in their business models. Extensive technological innovation boosts internet banking.

Development of IT Service Management in a Large International Company

The purpose of this Master’s thesis is to examine the IT Service Management (ITSM) capabilities of a large international company and develop a design for the IT Service Management of the company. The thesis consists of two parts: a literature review and a case study. The first part is the literature review. It examines different aspects of IT Service Management. The purpose of the literature review is to increase the credibility of the case study. In the case study, the IT Service Management of a large industrial company is assessed, and an improved design for IT Service Management is created. The services are limited to common IT services, and management is limited to operative management. To assess and develop the case company’s IT Service Management, the IT organization and its ITSM capabilities are analyzed, and on the basis of the analyses, an improved IT Service Management model is created. As a result of the analyses, it was found out that the management of the IT organization is function-oriented. Therefore, the organization needs a management model that breaks the functional borders and brings services to the center of management. The designed model aspires to achieve this by defining IT services and modeling management processes from the service perspective.