Topologically correct intersection curves of tori and natural quadrics

This thesis provides efficient and robust algorithms for the computation of the intersection curve between a torus and a simple surface (e.g. a plane, a natural quadric or another torus), based on algebraic and numeric methods. The algebraic part includes the classification of the topological type of the intersection curve and the detection of degenerate situations like embedded conic sections and singularities. Moreover, reference points for each connected intersection curve component are determined. The required computations are realised efficiently by solving quartic polynomials at most and exactly by using exact arithmetic. The numeric part includes algorithms for the tracing of each intersection curve component, starting from the previously computed reference points. Using interval arithmetic, accidental incorrectness like jumping between branches or the skipping of parts are prevented. Furthermore, the environments of singularities are correctly treated. Our algorithms are complete in the sense that any kind of input can be handled including degenerate and singular configurations. They are verified, since the results are topologically correct and approximate the real intersection curve up to any arbitrary given error bound. The algorithms are robust, since no human intervention is required and they are efficient in the way that the treatment of algebraic equations of high degree is avoided.

Regional Differences in Living Standards in Eastern European Countries - Changes During the Transition

This research aimed to discover how differences in living standards between regional units changed during the period of transformation from 1990 to 1995 in Poland, the Slovak Republic, the Czech Republic and Hungary. The standard of living was measured by the so-called Living Standard Index (LSI), a composite taxonomic measure. Fixed reference points make it possible to compare the standard of living in regional administrative units and to study its dynamics. The analysis was country-specific, since the lists of variable were not fully identical for all the countries studied. The main tools used were LSI variability measures (mainly variance and standard deviation). By identifying trend patterns in the characteristics of LSIs, it was possible to compare the different countries. It was found that * differences in living standards between regional units have been decreasing during the transformation in Poland and in the Czech Republic. In the latter this process is slow and smooth, while in Poland there was a relatively sharp decline which then stopped entirely in 1994 * the only country with increasing differences between regions is Hungary and these differences are growing at a constant rate * the lowest level of regional differences in the LSI was found in Poland, followed by the Slovak Republic and the Czech Republic * the regional differences in Hungary are almost twice as high as in the Czech Republic

Servizi Sociali Territoriali e Università: Esempi di Sinergie Possibili per un Percorso di Qualità

Although – or because – social work education in Italy has for some 15 years now been exclusively in the domain of the university the relationship between the academic world and that of practice has been highly tenuous. Research is indeed being conducted by universities, but rarely on issues that are of immediate practice relevance. This means that forms of practice develop and become established habitually which are not checked against rigorous standards of research and that the creation of knowledge at academic level pays scant attention to the practice implications of social changes. This situation has been made even worse by the dwindling resources both in social services and at the level of the universities which means that bureaucratic procedures or imports of specialisations from other disciplines frequently dominate the development of practice instead of a theory-based approach to methodology. This development does not do justice to the actual requirements of Italian society faced with ever increasing post-modern complexity which is reflected also in the nature of social problems because it implies a continuation of a faith in modernity with its idea of technical, clear-cut solutions while social relations have decidedly moved beyond that belief. This discrepancy puts even greater strain on the personnel of welfare agencies and does ultimately not satisfy the ever increasing demands for quality and accountability of services on the part of users and the general public. Social workers badly lack fundamental theoretical reference points which could guide them in their difficult work to arrive at autonomous, situation-specific methodological answers not based on procedures but on analytical knowledge. Thirty years ago, in 1977, a Presidential Decree created the legal basis for the establishment of social service departments at the level of municipalities which created opportunities for the direct involvement of the community in the fight against exclusion. For this potential to be fully utilized it would have required the bringing together of three dimensions, the organizational structure, the opportunities for learning and research in the territory and the contribution by the professional community. As this did not occur social services in Italy still often retain the character of charity which does not concern itself with the actual causes of poverty and exclusion. This in turn affects the relationship with citizens in general who cannot develop trust in those services. Through uncritical processes of interaction Edgar Morin’s dictum manifests itself which is that without resorting to critical reflection on complexity interventions can often have an effect that totally the opposite to the original intention. An important element in setting up a dynamic interchange between academia and practice is the placement on professional social work courses. Here the looping of theory to practice and back to theory etc. can actually take place under the right organizational and conceptual conditions, more so than in abstract, and for practitioners often useless debates about the theory-practice connection. Furthermore, research projects at the University of Florence Social Work Department for instance aim at fostering theoretical reflection at the level of and with the involvement of municipal social service agencies. With a general constructive disposition towards research and some financial investment students were facilitated to undertake social service practice related research for their degree theses for instance in the city of Pistoia. In this way it was also possible to strengthen the confidence and professional identity of social workers as they became aware of the contribution their own discipline can make to practice-relevant research instead of having to move over to disciplines like psychology for those purposes. Examples of this fruitful collaboration were presented at a conference in Pistoia on 25 June 2007. One example is a thesis entitled ‘The object of social work’ and examines the difficult development of definitions of social work and comes to the conclusion that ‘nothing is more practical than a theory’. Another is on coping abilities as a necessary precondition for the utilization of resources supplied by social services in exceptional circumstances. Others deal with the actual sequence of interventions in crisis situations, and one very interestingly looks at time and how it is being constructed often differently by professionals and clients. At the same time as this collaboration on research gathers momentum in the Toscana, supervision is also being demanded more forcefully as complementary to research and with the same aim of profiling more strongly the professional identity of social work. Collaboration between university and social service filed is for mutual benefit. At a time when professional practice is under threat of being defined from the outside through bureaucratic prescriptions a sound grounding in theory is a necessary precondition for competent practice.

Aussichten der freien Schulwahl. Die globale pädagogische Reformbewegung im Härtetest der direkten Demokratie

Weltweit ist eine Angleichung von Bildungsreformen zu beobachten, was im Begriff der globalen pädagogischen Reformbewegung zum Ausdruck kommt. Obwohl die Bedingungen, unter denen sich Nationalstaaten einer pädagogischen Weltkultur angleichen, in jüngster Zeit vermehrt untersucht wurden, ist über die politischen Mechanismen, die über die Rezeption globaler Modelle befinden, wenig bekannt. Anhand einer Fallstudie aus der Schweiz, deren System der direkten Demokratie besonders geeignet scheint, politische Transformationsprozesse zu untersuchen, wird die Auseinandersetzung um die Einführung der freien Schulwahl, wie sie durch verschiedene Volksinitiativen ausgelöst wurde, rekonstruiert. Die Studie zeigt, dass ein neoinstitutionalistischer Ansatz geeignet sein kann, die Rezeption globaler Reformmodelle zu erklären, sofern er um eine akteurtheoretische Perspektive ergänzt wird und die Besonderheiten des lokalen politischen Systems berücksichtigt werden. In methodischer Hinsicht ergibt sich, dass bei der Untersuchung globaler Angleichungsprozesse vier Referenzpunkte zu beachten sind, nämlich Staat, Markt, Öffentlichkeit und Wissenschaft

Applying prospect theory to predict new venture creation

Although prior research on new venture creation has identified several antecedents that differentiate entrepreneurs from non-entrepreneurs, scholars still have an incomplete understanding of the factors and decision processes that lead an individual to become an entrepreneur. By applying prospect theory, we introduce the reference point as an important antecedent of new venture creation. Testing our research model and hypotheses with entrepreneurs and employees, results show that entrepreneurs set more aspiring reference points and therefore find themselves more often in a perceived loss situation. Results are also robust when testing for entrepreneurial intention of business graduate students. According to prospect theory, the perceived loss triggers more risk-seeking behavior. Summing up, the reference point has a positive effect on new venture creation and differentiates entrepreneurs from nonentrepreneurs. We discuss theoretical and managerial implications of the findings and develop avenues for future research.

Hochwasser-«Katastrophen» in Basel vom 13. bis 21. Jahrhundert Rekonstruktion, Deutung und Lerneffekte

Magnitudes of peak discharges of 43 non-instrumentally measured Rhine river floods at Basel were reconstructed. The methodology is based on a range of different historic sources, containing flood information (including traditional urban inundation reference points from flood reports of medieval and early modern period chroniclers as well as 19th century journalists, flood marks, paintings and drawings, town maps, longitudinal and cross profiles etc.). These traditional pre-instrumental “flood information systems” still existed in the 19th century, when in 1808 the first instrumental hydrological measurements started. They thus could be calibrated with instrumental measurements in the 19th century overlapping period. The result is a 743 year long quantified Rhine river flood series. Floods of both periods (pre-instrumental as well as instrumental) can thus be directly compared for the very first time. The long-range consequences of rivers Kander and Aare deviations in 1714 and 1878 are reflected in a distinct change of magnitudes of peak discharges in Basel. A clear flood “disaster gap” appears in the 20th century. The lack of any extreme floods for such a long time is completely unique during the 743-year period of analysis. This result will influence the statistical assessment of once-in-a-century events, which might be of great interest for insurance campanies.

A 3-D CT assisted Monte Carlo evaluation of intracavitary brachytherapy implants

Intracavitary brachytherapy (ICB) combined with external beam irradiation for treatment of cervical cancer is highly successful in achieving local control. The M.D. Anderson Cancer Center employs Fletcher Suit Delclos (FSD) applicators. FSD applicators contain shields to limit dose to critical structures. Dosimetric evaluation of ICB implants is limited to assessing dose at reference points. These points serve as surrogates for treatment intensity and critical structure dose. Several studies have mentioned that the ICRU38 reference points inadequately characterize the dose distribution. Also, the ovoid shields are rarely considered in dosimetry. ^ The goal of this dissertation was to ascertain the influence of the ovoid shields on patient dose distributions. Monte Carlo dosimetry (MCD) was applied to patient computed tomography(CT) scans. These data were analyzed to determine the effect of the shields on dose to standard reference points and the bladder and rectum. The hypothesis of this work is that the ICRU38 bladder and rectal points computed conventionally are not clinically acceptable surrogates for the maximum dose points as determined by MCD. ^ MCD was applied to the tandem and ovoids. The FSD ovoids and tandem were modeled in a single input file that allowed dose to be calculated for any patient. Dose difference surface histograms(DDSH) were computed for the bladder and rectum. Reference point doses were compared between shielded and unshielded ovoids, and a commercial treatment planning system. ^ The results of this work showed the tandem tip screw caused a 33% reduction in dose. The ovoid shields reduced the dose by a maximum of 48.9%. DDSHs revealed on average 5% of the bladder surface area was spared 53 cGy and 5% of the rectal surface area was spared 195 cGy. The ovoid shields on average reduced the dose by 18% for the bladder point and 25% for the rectal point. The Student's t-test revealed the ICRU38 bladder and rectal points do not predict the maximum dose for these organs. ^ It is concluded that modeling the tandem and ovoid internal structures is necessary for accurate dose calculations, the bladder shielding segments may not be necessary, and that the ICRU38 bladder point is irrelevant. ^

Pasiones del riesgo y contacto con la naturaleza

Muchos deportistas aficionados en occidente, están emprendiendo hoy en día, largas e intensas ordalías donde la capacidad personal de resistir al sufrimiento en aumento constituye el objetivo principal. La carrera, el footing, el triatlón, el trekking, etc., son tipos de ordalías en las que la gente, sin apoyarse en una habilidad específica, no compite contra otros, sino que somete a prueba su propia capacidad para soportar el dolor creciente. El individuo se evalúa constantemente a sí mismo en una sociedad donde los puntos de referencia son incontables y contradictorios, donde los valores están en crisis, y busca entonces una relación cercana con significados profundos, probando su fuerza de carácter, su coraje y sus recursos personales. Seguir adelante hasta final de las ordalías autoimpuestas da una legitimidad a la vida y provee un umbral simbólico en el cual apoyarse. El funcionamiento en sí mismo tiene una importancia secundaria; sólo cuenta para el individuo. No se trata de luchar contra un tercero, es sólo un método para reforzar la voluntad personal y vencer el sufrimiento, justo al límite de una demanda personalmente impuesta. El límite físico ha venido a sustituir el límite moral que la sociedad actual no logra proporcionar. Sobreponiéndose al sufrimiento se templa el carácter del individuo, proporcionando así una importancia renovada y valiosa a su vida

Pasiones del riesgo y contacto con la naturaleza

Muchos deportistas aficionados en occidente, están emprendiendo hoy en día, largas e intensas ordalías donde la capacidad personal de resistir al sufrimiento en aumento constituye el objetivo principal. La carrera, el footing, el triatlón, el trekking, etc., son tipos de ordalías en las que la gente, sin apoyarse en una habilidad específica, no compite contra otros, sino que somete a prueba su propia capacidad para soportar el dolor creciente. El individuo se evalúa constantemente a sí mismo en una sociedad donde los puntos de referencia son incontables y contradictorios, donde los valores están en crisis, y busca entonces una relación cercana con significados profundos, probando su fuerza de carácter, su coraje y sus recursos personales. Seguir adelante hasta final de las ordalías autoimpuestas da una legitimidad a la vida y provee un umbral simbólico en el cual apoyarse. El funcionamiento en sí mismo tiene una importancia secundaria; sólo cuenta para el individuo. No se trata de luchar contra un tercero, es sólo un método para reforzar la voluntad personal y vencer el sufrimiento, justo al límite de una demanda personalmente impuesta. El límite físico ha venido a sustituir el límite moral que la sociedad actual no logra proporcionar. Sobreponiéndose al sufrimiento se templa el carácter del individuo, proporcionando así una importancia renovada y valiosa a su vida

Pasiones del riesgo y contacto con la naturaleza

Muchos deportistas aficionados en occidente, están emprendiendo hoy en día, largas e intensas ordalías donde la capacidad personal de resistir al sufrimiento en aumento constituye el objetivo principal. La carrera, el footing, el triatlón, el trekking, etc., son tipos de ordalías en las que la gente, sin apoyarse en una habilidad específica, no compite contra otros, sino que somete a prueba su propia capacidad para soportar el dolor creciente. El individuo se evalúa constantemente a sí mismo en una sociedad donde los puntos de referencia son incontables y contradictorios, donde los valores están en crisis, y busca entonces una relación cercana con significados profundos, probando su fuerza de carácter, su coraje y sus recursos personales. Seguir adelante hasta final de las ordalías autoimpuestas da una legitimidad a la vida y provee un umbral simbólico en el cual apoyarse. El funcionamiento en sí mismo tiene una importancia secundaria; sólo cuenta para el individuo. No se trata de luchar contra un tercero, es sólo un método para reforzar la voluntad personal y vencer el sufrimiento, justo al límite de una demanda personalmente impuesta. El límite físico ha venido a sustituir el límite moral que la sociedad actual no logra proporcionar. Sobreponiéndose al sufrimiento se templa el carácter del individuo, proporcionando así una importancia renovada y valiosa a su vida

Topographic model of Greenland (elevation lines in PanMap and ASCII format)

In this paper, a new high-resolution elevation model of Greenland, including the ice sheet as well as the ice free regions, is presented. It is the first published full coverage model, computed with an average resolution of 2 km and providing an unprecedented degree of detail. The topography is modeled from a wide selection of data sources, including satellite radar altimetry from Geosat and ERS 1, airborne radar altimetry and airborne laser altimetry over the ice sheet, and photogrammetric and manual map scannings in the ice free region. The ice sheet model accuracy is evaluated by omitting airborne laser data from the analysis and treating them as ground truth observations. The mean accuracy of the ice sheet elevations is estimated to be 12-13 m, and it is found that on surfaces of a slope between 0.2° and 0.8°, corresponding to approximately 50% of the ice sheet, the model presents a 40% improvement over models based on satellite altimetry alone. On coastal bedrock, the model is compared with stereo triangulated reference points, and it is found that the model accuracy is of the order of 25-35 m in areas covered by stereo photogrammetry scannings and between 200 and 250 m elsewhere.

Air photography Samoylov Island

For the qualitative description of surface properties like vegetation cover or land-water-ratio of Samoylov Island as well as for the evaluation of fetch homogeneity considerations of the eddy covariance measurements and for the up-scaling of chamber flux measurements, a detailed surface classification of the island at the sub-polygonal scale is necessary. However, up to know only grey-scale Corona satellite images from the 1960s with a resolution of 2 x 2 m and recent multi-spectral LandSat images with a resolution of 30 x 30 m were available for this region. Both are not useable for the desired classification because of missing spectral information and inadequate resolution, respectively. During the Lena 2003 expedition, a survey of the island by air photography was carried out in order to obtain images for surface classification. The photographs were taken from a helicopter on 10.07.2002, using a Canon EOS100 reflex camera, a Soligor 19-23 mm lens and colour slide film. The height from which the photographs were taken was approximately 600 meters. Due to limited flight time, not all the area of the island could be photographed and some regions could only be photographed with a slanted view. As a result, the images are of a varying quality and resolution. In Potsdam, after processing the films were scanned using a Nikon LS-2000 scanner at maximal resolution setting. This resulted in a ground resolution of the scanned images of approximately 0.3x0.3 m. The images were subsequently geo-referenced using the ENVI software and a referenced Corona image dating from 18.07.1964 (Spott, 2003). Geo-referencing was only possible for the Holocene river terrace areas; the floodplain regions in the western part of the island could not be referenced due to the lack of ground reference points. In Figure 3.7-1, the aerial view of Samoylov Island composed of the geo-referenced images is shown. Further work is necessary for the classification and interpretation of the images. If possible, air photography surveys will be carried out during future expeditions in order to determine changes in surface pattern and composition.

Cartography for cooperative manoeuvres with autonomous land vehicles

This article presents a cartographic system to facilitate cooperative manoeuvres among autonomous vehicles in a well-known environment. The main objective is to design an extended cartographic system to help in the navigation of autonomous vehicles. This system has to allow the vehicles not only to access the reference points needed for navigation, but also noticeable information such as the location and type of traffic signals, the proximity to a crossing, the streets en route, etc. To do this, a hierarchical representation of the information has been chosen, where the information has been stored in two levels. The lower level contains the archives with the Universal Traverse Mercator (UTM) coordinates of the points that define the reference segments to follow. The upper level contains a directed graph with the relational database in which streets, crossings, roundabouts and other points of interest are represented. Using this new system it is possible to know when the vehicle approaches a crossing, what other paths arrive at that crossing, and, should there be other vehicles circulating on those paths and arriving at the crossing, which one has the highest priority. The data obtained from the cartographic system is used by the autonomous vehicles for cooperative manoeuvres.

Localization and Tracking in Energy-Constrained Networks with Dynamic Connectivity

Systems used for target localization, such as goods, individuals, or animals, commonly rely on operational means to meet the final application demands. However, what would happen if some means were powered up randomly by harvesting systems? And what if those devices not randomly powered had their duty cycles restricted? Under what conditions would such an operation be tolerable in localization services? What if the references provided by nodes in a tracking problem were distorted? Moreover, there is an underlying topic common to the previous questions regarding the transfer of conceptual models to reality in field tests: what challenges are faced upon deploying a localization network that integrates energy harvesting modules? The application scenario of the system studied is a traditional herding environment of semi domesticated reindeer (Rangifer tarandus tarandus) in northern Scandinavia. In these conditions, information on approximate locations of reindeer is as important as environmental preservation. Herders also need cost-effective devices capable of operating unattended in, sometimes, extreme weather conditions. The analyses developed are worthy not only for the specific application environment presented, but also because they may serve as an approach to performance of navigation systems in absence of reasonably accurate references like the ones of the Global Positioning System (GPS). A number of energy-harvesting solutions, like thermal and radio-frequency harvesting, do not commonly provide power beyond one milliwatt. When they do, battery buffers may be needed (as it happens with solar energy) which may raise costs and make systems more dependent on environmental temperatures. In general, given our problem, a harvesting system is needed that be capable of providing energy bursts of, at least, some milliwatts. Many works on localization problems assume that devices have certain capabilities to determine unknown locations based on range-based techniques or fingerprinting which cannot be assumed in the approach considered herein. The system presented is akin to range-free techniques, but goes to the extent of considering very low node densities: most range-free techniques are, therefore, not applicable. Animal localization, in particular, uses to be supported by accurate devices such as GPS collars which deplete batteries in, maximum, a few days. Such short-life solutions are not particularly desirable in the framework considered. In tracking, the challenge may times addressed aims at attaining high precision levels from complex reliable hardware and thorough processing techniques. One of the challenges in this Thesis is the use of equipment with just part of its facilities in permanent operation, which may yield high input noise levels in the form of distorted reference points. The solution presented integrates a kinetic harvesting module in some nodes which are expected to be a majority in the network. These modules are capable of providing power bursts of some milliwatts which suffice to meet node energy demands. The usage of harvesting modules in the aforementioned conditions makes the system less dependent on environmental temperatures as no batteries are used in nodes with harvesters--it may be also an advantage in economic terms. There is a second kind of nodes. They are battery powered (without kinetic energy harvesters), and are, therefore, dependent on temperature and battery replacements. In addition, their operation is constrained by duty cycles in order to extend node lifetime and, consequently, their autonomy. There is, in turn, a third type of nodes (hotspots) which can be static or mobile. They are also battery-powered, and are used to retrieve information from the network so that it is presented to users. The system operational chain starts at the kinetic-powered nodes broadcasting their own identifier. If an identifier is received at a battery-powered node, the latter stores it for its records. Later, as the recording node meets a hotspot, its full record of detections is transferred to the hotspot. Every detection registry comprises, at least, a node identifier and the position read from its GPS module by the battery-operated node previously to detection. The characteristics of the system presented make the aforementioned operation own certain particularities which are also studied. First, identifier transmissions are random as they depend on movements at kinetic modules--reindeer movements in our application. Not every movement suffices since it must overcome a certain energy threshold. Second, identifier transmissions may not be heard unless there is a battery-powered node in the surroundings. Third, battery-powered nodes do not poll continuously their GPS module, hence localization errors rise even more. Let's recall at this point that such behavior is tight to the aforementioned power saving policies to extend node lifetime. Last, some time is elapsed between the instant an identifier random transmission is detected and the moment the user is aware of such a detection: it takes some time to find a hotspot. Tracking is posed as a problem of a single kinetically-powered target and a population of battery-operated nodes with higher densities than before in localization. Since the latter provide their approximate positions as reference locations, the study is again focused on assessing the impact of such distorted references on performance. Unlike in localization, distance-estimation capabilities based on signal parameters are assumed in this problem. Three variants of the Kalman filter family are applied in this context: the regular Kalman filter, the alpha-beta filter, and the unscented Kalman filter. The study enclosed hereafter comprises both field tests and simulations. Field tests were used mainly to assess the challenges related to power supply and operation in extreme conditions as well as to model nodes and some aspects of their operation in the application scenario. These models are the basics of the simulations developed later. The overall system performance is analyzed according to three metrics: number of detections per kinetic node, accuracy, and latency. The links between these metrics and the operational conditions are also discussed and characterized statistically. Subsequently, such statistical characterization is used to forecast performance figures given specific operational parameters. In tracking, also studied via simulations, nonlinear relationships are found between accuracy and duty cycles and cluster sizes of battery-operated nodes. The solution presented may be more complex in terms of network structure than existing solutions based on GPS collars. However, its main gain lies on taking advantage of users' error tolerance to reduce costs and become more environmentally friendly by diminishing the potential amount of batteries that can be lost. Whether it is applicable or not depends ultimately on the conditions and requirements imposed by users' needs and operational environments, which is, as it has been explained, one of the topics of this Thesis.

A water footprint assessment of a pair of jeans: the influence of agricultural policies on the sustainability of consumer products.

This study reports the results of a water footprint (WF) assessment of five types of textiles commonly used for the production of jeans, including two different fibres (cotton and Lyocell fibre) and five corresponding production methods for spinning, dyeing and weaving. The results show that the fibre production is the stage with the highest water consumption, being cotton production particularly relevant. Therefore, the study pays particular attention to the water footprint of cotton production and analyses the effects of external factors influencing the water footprint of a product, in this case, the incentives provided by the EU Common Agricultural Policy (CAP), and the relevance of agricultural practices to the water footprint of a product is emphasised. An extensification of the crop production led to higher WF per unit, but a lower overall pressure on the basins water resources. This study performs a sustainability assessment of the estimated cotton WFs with the water scarcity index, as proposed by Hoekstra et al. (2011), and shows their variations in different years as a result of different water consumption by crops in the rest of the river basin. In our case, we applied the assessment to the Guadalquivir, Guadalete and Barbate river basins, three semi-arid rivers in South Spain. Because they are found to be relevant, the available water stored in dams and the outflow are also incorporated as reference points for the sustainability assessment. The study concludes that, in the case of Spanish cotton production, the situation of the basin and the policy impact are more relevant for the status of the basin s water resources than the actual WF of cotton production. Therefore, strategies aimed at reducing the impact of the water footprint of a product need to analyse both the WF along the value chain and within the local context.