Product management as an organizational system has a long history of practice, which predates most modern academic management research. Its activities span the external environment of the firm, while simultaneously spanning across internal functional specialties of the organization. Thus product management obtains, codifies, simplifies and stores external information making it available to a responsive organization, which uses it to establish competitive advantage and ultimately superior performance. Building on the resource based view of the firm and boundary theory, these spanning activities, which are heterogeneously dispersed across firms, are considered organizational capabilities. Drawing upon the extant product management literature, this research uses product management as a proxy for boundary spanning capabilities of the firm. These capabilities are then empirically measured against two well established firm capabilities; market orientation and firm-level innovativeness. This research addresses a gap in the literature by establishing product management as a set of firm-level capabilities, distinct from the well established constructs of market orientation and innovativeness. Results indicate that external product management capability, defined as channel bonding activities, fully mediates the market orientation – firm performance relationship, while firm level innovativeness continues to have a small mediating effect on performance. Internal product management capabilities, defined as market and technical integration are shown to negatively moderate the external product management capability - firm performance relationship. Theoretical implications include establishing a link between boundary theory and the resource based view of the firm. Practical implications include the strong relationship between external spanning capabilities and firm performance and the dampening effect of cross-functional integration on firm performance. This empirical link between product management boundary spanning practices and how firms ultimately perform could assist practitioners in allocating resources and managing the relationship between the marketing and technological factions of the organization. Most importantly this research establishes the hereto untested link between product management capability and firm performance.

With the increasing demand on multimedia applications over the Internet, and the growing number of mobile smart devices people are using, it is helpful to develop a mobile network architecture that can support multimedia transmission without using infrastructures. We propose that service overlay networks over MANETs can serve as a supplement to the existing 3G/4G networks and Wi-Fi access point networks. In this thesis we present experiment results that show the feasibility of mobile service overlay networks to meet the requirements of multimedia streaming. And also, we improved one of the existing overlay protocols. The improved protocol takes physical location into consideration when establishing connections in the overlay network. It also limits the number of neighbors each node can have, which prevents a particular node from becoming the bottleneck of the network, when connected to too many neighbors. Evaluation results show the new protocol reduces network packet loss rate.

With the increasing demand on multimedia applications over the Internet, and the growing number of mobile smart devices people are using, it is helpful to develop a mobile network architecture that can support multimedia transmission without using infrastructures. We propose that service overlay networks over MANETs can serve as a supplement to the existing 3G/4G networks and Wi-Fi access point networks. In this thesis we present experiment results that show the feasibility of mobile service overlay networks to meet the requirements of multimedia streaming. And also, we improved one of the existing overlay protocols. The improved protocol takes physical location into consideration when establishing connections in the overlay network. It also limits the number of neighbors each node can have, which prevents a particular node from becoming the bottleneck of the network, when connected to too many neighbors. Evaluation results show the new protocol reduces network packet loss rate.

We propose algorithms for organization of images in wide-area sparse-view datasets. In such datasets, if the images overlap in scene content, they are related by wide-baseline geometric transformations. The challenge is to identify these relations even if the images sparingly overlap in their content. The images in a dataset are then grouped into sets of related images with the relations captured in each set as a basal (minimal and foundational) graph structures. Images form the vertices in the graph structure and the edges define the geometric relations between the images. We use these basal graphs for geometric walkthroughs and detection of noisy location (GPS) and orientation (magnetometer) information that may be stored with each image. We have five algorithmic contributions. First, we propose an algorithm BLOGS (Balanced Local and Global Search) that uses a novel hybrid Markov Chain Monte Carlo (MCMC) strategy called 'hop-diffusion' for epipolar geometry estimation between a pair of wide-baseline images that is 10 times faster and more accurate than the state-of-the-art. Hops are global searches and diffusions are local searches. BLOGS is able to handle very wide-baseline views characteristic of wide-area sparse-view datasets. It also produces a geometric match score between an image pair. Second, we propose a photometric match score, the Cumulative Correspondence Score (CCS). The proposed photometric scores are fast approximations of the computationally expensive geometric scores. Third, we use the photometric scores and the geometric scores to find groups of related images and to organize them in the form of basal graph structures using a novel hybrid algorithm we call theCOnnected component DIscovery by Minimally Specifying an Expensive Graph (CODIMSEG). The objective of the algorithm is to minimize the number of geometric estimations and yield results similar to what would be achieved if all-pair geometric matching were done. We compared the performances of the CCS and CODIMSEG algorithms with GIST (means summary of an image) and k-Nearest Neighbor (k-NN) based approaches. We found that CCS and CODIMSEG perform significantly better than GIST and k-NN respectively in identifying visually connected images. Our algorithm achieved more than 95% true positive rate at 0% false positive rate. Fourth, we propose a basal tree graph expansion algorithm to make the basal graphs denser for applications like geometric walk-throughs using the minimum Hamiltonian path algorithm and detection of noisy position (GPS) and orientation (magnetometer) tags. We propose two versions of geometric walkthroughs, one using minimum spanning tree based approximation of the minimum Hamiltonian path on the basal tree graphs and other using the Lin-Kernighan heuristic approximation on the expanded basal graph. Conversion of a non-linear tree structure to a linear path structure leads to discontinuities in path. The Lin-Kernighan algorithm on the expanded basal graphs is shown to be a better approach. Fifth, we propose a vision based geometric voting algorithm to detect noisy GPS and magnetometer tags using the basal graphs. This problem has never been addressed before to the best of our knowledge. We performed our experiments on the Nokia dataset (which has 243 images in the 'Lausanne' dataset and 105 images in the 'Demoset'), ArtQuad dataset (6514 images) and Oxford dataset (5063 images). All the three datasets are very different. Nokia dataset is a very wide-baseline sparse-view dataset. ArtQuad dataset is a wide-baseline dataset with denser views compared to the Nokia dataset. Both these datasets have GPS tagged images. Nokia dataset has magnetometer tags too. ArtQuad dataset has 348 images with the commercial GPS information as well as high precision differential GPS data which serves as ground truth for our noisy tag detection algorithm. Oxford dataset is a wide-baseline dataset with plenty of distracters that test the algorithm's capability to group images correctly. The larger datasets test the scalability of our algorithms. Visually inspected feature matches and image matches were used as ground truth in our experiments. All the experiments were done on a single PC.

While the role of the school principal has received much attention in stable environments, little research exists on principals working in conflict-affected countries. The purpose of this phenomenological study is to uncover perceptions of Somali principals in Mogadishu regarding their roles and lived experiences, as well as the challenges they face as they lead their schools amid ongoing conflict. In order to understand the different dimensions of the principal’s role and how this role is experienced in such a context, a descriptive phenomenology has been employed. A purposeful sample of eight primary school principals in Mogadishu, which has been the epicentre of the ongoing conflict, was indentified and the principals were interviewed. Through the six-step approach to phenomenological data analysis, as suggested by Creswell (2013), 11 themes were identified. Findings revealed that principals perceived their role as supporting teachers personally and professionally, supervising instruction, facilitating teacher professional development when the security situation permits, having good relationships with governing bodies, and building community collaboration. Findings also showed that, besides security concerns, student mobility, poor facilities, shortage of trained teachers and student discipline were the major challenges to principals. Findings further indicated that principals acted as boundary spanners using a variety of buffering and bridging strategies in an attempt to minimize uncertainty and security risks, as well as to adapt the school to the volatile environment. Furthermore, commitment to keep schools open, despite the huge challenges, a sense of responsibility for student safety, and calm and courageous actions in the face of danger were perceived as critical factors in sustaining principals in their positions. Four conclusions were drawn from the study, including principals’ lack of unity in the perception of their roles, principals’ lack of pre-service training, the possibility and essentiality of providing education during armed conflicts, and the importance of creating strong bonds through principals’ supportive roles. Recommendations were offered for primary principals, local educational umbrellas, NGOs, and UN agencies, as well as for further research possibilities.

In this thesis, we make some contributions at the interface between algebra and graph theory. In Chapter 1, we give an overview of the topics and also the definitions and preliminaries. In Chapter 2, we estimate the number of possible types degree patterns of k-lacunary polynomials of degree t < p which split completely modulo p. The result is based on a rather unusual combination of two techniques: a bound on the number of zeros of lacunary polynomials and a bound on the so-called domination number of a graph. In Chapter 3, we deal with the determinant of bipartite graphs. The nullity of a graph G is the multiplicity of 0 in the spectrum of G. Nullity of a (molecular) graph (e.g., a bipartite graph corresponding to an alternant hydrocarbon) has important applications in quantum chemistry and Huckel molecular orbital (HMO) theory. A famous problem, posed by Collatz and Sinogowitz in 1957, asks to characterize all graphs with positive nullity. Clearly, examining the determinant of a graph is a way to attack this problem. In this Chapter, we show that the determinant of a bipartite graph with at least two perfect matchings and with all cycle lengths divisible by four, is zero. In Chapter 4, we first introduce an application of spectral graph theory in proving trigonometric identities. This is a very simple double counting argument that gives very short proofs for some of these identities (and perhaps the only existed proof in some cases!). In the rest of Chapter 4, using some properties of the well-known Chebyshev polynomials, we prove some theorems that allow us to evaluate the number of spanning trees in join of graphs, Cartesian product of graphs, and nearly regular graphs. In the last section of Chapter 4, we obtain the number of spanning trees in an (r,s)-semiregular graph and its line graph. Note that the same results, as in the last section, were proved by I. Sato using zeta functions. But our proofs are much shorter based on some well-known facts from spectral graph theory. Besides, we do not use zeta functions in our arguments. In Chapter 5, we present the conclusion and also some possible projects.

Image segmentation has an important role in image processing because it is a tool to obtain higher level object descriptions for further processing. In some applications such as large image databases or video image sequence segmentations, the speed of the segmentation algorithm may become a drawback of the application. This thesis work is a study to improve the run-time performance of a well-known segmentation algorithm, namely the Recursive Shortest Spanning Tree (RSST). Both the original and the fast RSST found in the literature are analyzed and a comparison is made between these techniques. Simple modifications and an alternative link cost structure are proposed and evaluated. Finally, a distributed implementation based on a simple image partitioning strategy is attempted. The thesis presents the results of an extensive computational study with respect to both run-time performance and image segmentation quality.

Today's global market means that raw materials are sought and bought from all over the world. This creates an higher demand for a well-functioning supply chain. In our thesis we have studied a large paper mill in northen Sweden which experiences issues with flow of raw material. Our aim has hence been to examine which aspects affect the flow of raw materials to the mill, and how these can be adressed using an IT-system. The question we sought to answer was; What factors are important to consider and how do these affect the ability of an IT-system which will support the flow of raw material at the paper mill? We have found that the problems are strongly connected to the low amount of information sharing between the mill and the suppliers. We have come to the conclusion that the paper mill and the suppliers could benefit from boundary-spanning, and that a so-called awareness display which indicates current capacity would support that.

Hlavním cílem této práce je vyložit a zejména propojit existující metodologii filtrování korelačních matic, grafových algoritmů aplikovaných na minimální kostry grafu, hierarchického shlukování a analýzy hlavních komponent, pro vytvoření kvantitativních investičních strategií. Namísto tradičního použití časových řad akciových výnosů je užito reziduí z faktorových modelů. Tato rezidua jsou klíčovým vstupem pro všechny používané algoritmy k výpočtu pravděpodobnosti středovosti dané akcie. Pravděpodobnost středovosti je nekonvenční ukazatel pravděpodobnosti, kde hodnota blízko 1 značí vysokou pravděpodobnost středovosti dané akcie v dané ekonomické síti. Na základě této míry pravděpodobnosti je vybudováno několik investičních strategií, které jsou dále testován hlavních amerických akciových indexů. Nemůže být generalizováno, že periferní strategie dosahují konzistentně lepších výsledků než středové strategie. Zatímco při použití klasického Markowitzova optimalizačního procesu jsou zisky stabilní a potenciál průměrný, oba typy vybudovaných strategií (středové i periferní) sdílí vysoký potenciál zisku, který je ovšem vykoupen vysokou volatilitou.

Cette thèse porte sur différents problèmes d'optimisation combinatoire dont nous avons caractérisé la difficulté en décrivant des réductions et des algorithmes polynomiaux exacts ou approchés.En particulier, nous étudions le problème de trouver, dans un graphe orienté sans cycle dont les sommets sont étiquetés, un chemin qui passe par un maximum d'étiquettes différentes. Nous établissons qu'il n'existe pas d'algorithme polynomial avec un facteur constant pour ce problème. Nous présentons aussi un schéma qui permet d'obtenir, pour tout $epsilon >0$, un algorithme polynomial qui calcule un chemin collectant $ O(OPT^{1-epsilon})$ étiquettes.Nous étudions ensuite des variantes du problème de l'arbre couvrant de poids minimum auquel nous ajoutons des contraintes de distance et d'intermédiarité. Nous prouvons que certaines variantes se résolvent en temps polynomial comme des problèmes de calcul d'un libre de poids minimum commun à deux matroïdes. Pour une autre variante, nous présentons un algorithme d'approximation facteur 2 et nous prouvons qu'il n'existe pas d'algorithme polynomial avec un meilleur facteur constant.Enfin, nous étudions un problème d'améliorations de réseaux du point de vue du partage des coûts. Nous montrons que la fonction de coût associée à ce problème est sous-modulaire et nous utilisons ce résultat pour déduire un mécanisme de partage des coûts qui possède plusieurs bonnes propriétés. / In this thesis, we investigate several combinatorial optimization problems and characterize their computational complexity and approximability by providing polynomial reductions and exact or approximation algorithms.In particular, we study the problem of finding, in a vertex-labeled directed acyclic graph, a path collecting a maximum number of distinct labels. We prove that no polynomial time constant factor approximation algorithm exists for this problem. Furthermore, we describe a scheme that produces, for any $epsilon >0$, a polynomial time algorithm that computes a solution collecting $O(OPT^{1-epsilon})$ labels. Then, we study several variants of the minimum cost spanning tree problem that take into account distance and betweenness constraints. We prove that most of these problems can be solved in polynomial time using a reduction to the weighted matroid intersection problem. For an other problem, we give a factor 2 approximation algorithm and prove the optimality of this ratio.Finally, we study a network improvement problem from a cost sharing perspective. We establish that the cost function corresponding to this problem is submodular and use this result to derive a cost sharing mechanism having several good properties.