Exploring 3D Shapes through Real Functions

This thesis lays in the context of research on representation, modelling and coding knowledge related to digital shapes, where by shape it is meant any individual object having a visual appareance which exists in some two-, three- or higher dimensional space. Digital shapes are digital representations of either physically existing or virtual objects that can be processed by computer applications. While the technological advances in terms of hardware and software have made available plenty of tools for using and interacting with the geometry of shapes, to manipulate and retrieve huge amount of data it is necessary to define methods able to effectively code them. In this thesis a conceptual model is proposed which represents a given 3D object through the coding of its salient features and defines an abstraction of the object, discarding irrelevant details. The approach is based on the shape descriptors defined with respect to real functions, which provide a very useful shape abstraction method for the analysis and structuring of the information contained in the discrete shape model. A distinctive feature of these shape descriptors is their capability of combining topological and geometrical information properties of the shape, giving an abstraction of the main shape features. To fully develop this conceptual model, both theoretical and computational aspects have been considered, related to the definition and the extension of the different shape descriptors to the computational domain. Main emphasis is devoted to the application of these shape descriptors in computational settings; to this aim we display a number of application domains that span from shape retrieval, to shape classification and to best view selection.Questa tesi si colloca nell\u27ambito di ricerca riguardante la rappresentazione, la modellazione e la codifica della conoscenza connessa a forme digitali, dove per forma si intende l\u27aspetto visuale di ogni oggetto che esiste in due, tre o pi? dimensioni. Le forme digitali sono rappresentazioni di oggetti sia reali che virtuali, che possono essere manipolate da un calcolatore. Lo sviluppo tecnologico degli ultimi anni in materia di hardware e software ha messo a disposizione una grande quantit? di strumenti per acquisire, rappresentare e processare la geometria degli oggetti; tuttavia per gestire questa grande mole di dati ? necessario sviluppare metodi in grado di fornirne una codifica efficiente. In questa tesi si propone un modello concettuale che descrive un oggetto 3D attraverso la codifica delle caratteristiche salienti e ne definisce una bozza ad alto livello, tralasciando dettagli irrilevanti. Alla base di questo approccio ? l\u27utilizzo di descrittori basati su funzioni reali in quanto forniscono un\u27astrazione della forma molto utile per analizzare e strutturare l\u27informazione contenuta nel modello discreto della forma. Una peculiarit? di tali descrittori di forma ? la capacit? di combinare propriet? topologiche e geometriche consentendo di astrarne le principali caratteristiche. Per sviluppare questo modello concettuale, ? stato necessario considerare gli aspetti sia teorici che computazionali relativi alla definizione e all\u27estensione in ambito discreto di vari descrittori di forma. Particolare attenzione ? stata rivolta all\u27applicazione dei descrittori studiati in ambito computazionale; a questo scopo sono stati considerati numerosi contesti applicativi, che variano dal riconoscimento alla classificazione di forme, all\u27individuazione della posizione pi? significativa di un oggetto

Large bichromatic point sets admit empty monochromatic 4-gons

We consider a variation of a problem stated by Erd˝os and Szekeres in 1935 about the existence of a number fES(k) such that any set S of at least fES(k) points in general position in the plane has a subset of k points that are the vertices of a convex k-gon. In our setting the points of S are colored, and we say that a (not necessarily convex) spanned polygon is monochromatic if all its vertices have the same color. Moreover, a polygon is called empty if it does not contain any points of S in its interior. We show that any bichromatic set of n ≥ 5044 points in R2 in general position determines at least one empty, monochromatic quadrilateral (and thus linearly many).Postprint (published version

The ecology and genetics of Chagas disease vectors in Ecuador, with emphasis on Rhodnius ecuadoriensis (Hemiptera: Reduviidae: Triatominae)

An estimate >11 million people are infected by Trypanosoma cruzi in Latin America. Chagas disease control programmes have been successful in the Southern Cone countries, and similar initiatives are underway in the Andean countries. In Ecuador prevalence is estimated as ~ 130000 people, with 2.5-3.8 million at risk; annual associated costs may reach >20 million US dollars. We studied ecological, genetic, and evolutionary aspects of Rhodnius ecuadoriensis, an important disease vector in western Ecuador and northwestern Peru. Sylvatic and synanthropic populations are sympatric in central Ecuador; only domestic-peridomestic colonies occur in the temperate Andean valleys of southern Ecuador and northern Peru. Both morphological-chromatic features and ecological-behavioural preferences seem to define a cline [sylvatic-large (north) - synanthropic-small (south)]. The ecology of domestic and sylvatic populations was studied using logistic regression. Phytelephas aequatorialis palms are the primary natural ecotope of R ecuadoriensis; sylvatic bugs tend to favour male palms with large amounts of decomposing organic material and located in cropland/pasture fields. Poor households with mud walls, tiled roofs and large numbers of chickens were more likely to be infested. Isometry-free morphometric analysis consistently achieved >90% correct discrimination of sylvatic vs. synanthropic populations, supporting the use of metric variables in surveillance of reinfestations; size-free analyses revealed substantial divergence of Peruvian bugs from La Libertad. Mitochondrial DNA sequence polymorphisms (cytochrome b gene, 663 basepairs) were analysed; ~4% sequence divergence scored between Ecuadorian and Peruvian populations suggested they are independent phylogroups. Haplotype diversity and relationships indicate central coastal Ecuador as the centre of dispersal of this species, with isolated domestic populations in dry Andean valleys. The phylogeny of this species was explored using morphometric and molecular approaches. The monophyly of the `Pacific Rhodnius lineage' (pallescens, colombiensis and ecuadoriensis) was confirmed, with the parapatric pallescens and colombiensis being very closely related; R. pictipes is the closest relative to this lineage among Amazonian species, with the robustus group forming a distinct, major Glade. Control of R ecuadoriensis can contemplate local eradication in dry Andean valleys (southern Ecuador and northern Peru); special attention should be paid to peridomestic populations, including improvement of poultry management (burning-replacing nests every 15-30 days). Long-term interruption of disease transmission would benefit from educational interventions increasing awareness about Chagas disease and from housing improvements targeting mud walls and timber-and-tile roofs. In central-northern western Ecuador peridomestic palm trees may be the origin of reinfestations; environmental management (removing dead fronds and fibres from peridomestic palms), and continuous community- based surveillance are recommended. A comprehensive control programme over 15 years would probably result in interruption of disease transmission, and could bring savings of about 20 US$ per each dollar invested.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Factors Influencing Customer Satisfaction towards E-shopping in Malaysia

Online shopping or e-shopping has changed the world of business and quite a few people have decided to work with these features. What their primary concerns precisely and the responses from the globalisation are the competency of incorporation while doing their businesses. E-shopping has also increased substantially in Malaysia in recent years. The rapid increase in the e-commerce industry in Malaysia has created the demand to emphasize on how to increase customer satisfaction while operating in the e-retailing environment. It is very important that customers are satisfied with the website, or else, they would not return. Therefore, a crucial fact to look into is that companies must ensure that their customers are satisfied with their purchases that are really essential from the ecommerce’s point of view. With is in mind, this study aimed at investigating customer satisfaction towards e-shopping in Malaysia. A total of 400 questionnaires were distributed among students randomly selected from various public and private universities located within Klang valley area. Total 369 questionnaires were returned, out of which 341 questionnaires were found usable for further analysis. Finally, SEM was employed to test the hypotheses. This study found that customer satisfaction towards e-shopping in Malaysia is to a great extent influenced by ease of use, trust, design of the website, online security and e-service quality. Finally, recommendations and future study direction is provided. Keywords: E-shopping, Customer satisfaction, Trust, Online security, E-service quality, Malaysia

The drivers of Corporate Social Responsibility in the supply chain. A case study.

Purpose: The paper studies the way in which a SME integrates CSR into its corporate strategy, the practices it puts in place and how its CSR strategies reflect on its suppliers and customers relations. Methodology/Research limitations: A qualitative case study methodology is used. The use of a single case study limits the generalizing capacity of these findings. Findings: The entrepreneur’s ethical beliefs and value system play a fundamental role in shaping sustainable corporate strategy. Furthermore, the type of competitive strategy selected based on innovation, quality and responsibility clearly emerges both in terms of well defined management procedures and supply chain relations as a whole aimed at involving partners in the process of sustainable innovation. Originality/value: The paper presents a SME that has devised an original innovative business model. The study pivots on the issues of innovation and eco-sustainability in a context of drivers for CRS and business ethics. These values are considered fundamental at International level; the United Nations has declared 2011 the “International Year of Forestry”