(Table 1) Age markers and errors for the last 1215 ka in IODP Exp302

Despite its importance in the global climate system, age-calibrated marine geologic records reflecting the evolution of glacial cycles through the Pleistocene are largely absent from the central Arctic Ocean. This is especially true for sediments older than 200 ka. Three sites cored during the Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition (ACEX), provide a 27 m continuous sedimentary section from the Lomonosov Ridge in the central Arctic Ocean. Two key biostratigraphic datums and constraints from the magnetic inclination data are used to anchor the chronology of these sediments back to the base of the Cobb Mountain subchron (1215 ka). Beyond 1215 ka, two best fitting geomagnetic models are used to investigate the nature of cyclostratigraphic change. Within this chronology we show that bulk and mineral magnetic properties of the sediments vary on predicted Milankovitch frequencies. These cyclic variations record ''glacial'' and ''interglacial'' modes of sediment deposition on the Lomonosov Ridge as evident in studies of ice-rafted debris and stable isotopic and faunal assemblages for the last two glacial cycles and were used to tune the age model. Potential errors, which largely arise from uncertainties in the nature of downhole paleomagnetic variability, and the choice of a tuning target are handled by defining an error envelope that is based on the best fitting cyclostratigraphic and geomagnetic solutions.

Petri Net Siphon Analysis and Network Centrality Measures for Identifying Combination Therapies in Signaling Pathways

Aberrant behavior of biological signaling pathways has been implicated in diseases such as cancers. Therapies have been developed to target proteins in these networks in the hope of curing the illness or bringing about remission. However, identifying targets for drug inhibition that exhibit good therapeutic index has proven to be challenging since signaling pathways have a large number of components and many interconnections such as feedback, crosstalk, and divergence. Unfortunately, some characteristics of these pathways such as redundancy, feedback, and drug resistance reduce the efficacy of single drug target therapy and necessitate the employment of more than one drug to target multiple nodes in the system. However, choosing multiple targets with high therapeutic index poses more challenges since the combinatorial search space could be huge. To cope with the complexity of these systems, computational tools such as ordinary differential equations have been used to successfully model some of these pathways. Regrettably, for building these models, experimentally-measured initial concentrations of the components and rates of reactions are needed which are difficult to obtain, and in very large networks, they may not be available at the moment. Fortunately, there exist other modeling tools, though not as powerful as ordinary differential equations, which do not need the rates and initial conditions to model signaling pathways. Petri net and graph theory are among these tools. In this thesis, we introduce a methodology based on Petri net siphon analysis and graph network centrality measures for identifying prospective targets for single and multiple drug therapies. In this methodology, first, potential targets are identified in the Petri net model of a signaling pathway using siphon analysis. Then, the graph-theoretic centrality measures are employed to prioritize the candidate targets. Also, an algorithm is developed to check whether the candidate targets are able to disable the intended outputs in the graph model of the system or not. We implement structural and dynamical models of ErbB1-Ras-MAPK pathways and use them to assess and evaluate this methodology. The identified drug-targets, single and multiple, correspond to clinically relevant drugs. Overall, the results suggest that this methodology, using siphons and centrality measures, shows promise in identifying and ranking drugs. Since this methodology only uses the structural information of the signaling pathways and does not need initial conditions and dynamical rates, it can be utilized in larger networks.

Women, Drug use and Imprisonment. Intersectional Approach

Research on women prisoners and drug use is scarce in our context and needs theoretical tools to understand their life paths. In this article, I introduce an intersectional perspective on the experiences of women in prison, with particular focus on drug use. To illustrate this, I draw on the life story of one of the women interviewed in prison, in order to explore the axes of inequality in the lives of women in prison. These are usually presented as accumulated and articulated in complex and diverse ways. The theoretical tool of intersectionality allows us to gain an understanding of the phenomenon of women prisoners who have used drugs. This includes both the structural constraints in which they were embedded and the decisions they made, considering the circumstances of disadvantage in which they were immersed. This is a perspective which has already been intuitively present since the dawn of feminist criminology in the English-speaking world and can now be developed further due to new contributions in this field of gender studies.

Large-scale dynamic hydrofracturing, healing and fracture network characterization

Permeability of a rock is a dynamic property that varies spatially and temporally. Fractures provide the most efficient channels for fluid flow and thus directly contribute to the permeability of the system. Fractures usually form as a result of a combination of tectonic stresses, gravity (i.e. lithostatic pressure) and fluid pressures. High pressure gradients alone can cause fracturing, the process which is termed as hydrofracturing that can determine caprock (seal) stability or reservoir integrity. Fluids also transport mass and heat, and are responsible for the formation of veins by precipitating minerals within open fractures. Veining (healing) thus directly influences the rock’s permeability. Upon deformation these closed factures (veins) can refracture and the cycle starts again. This fracturing-healing-refacturing cycle is a fundamental part in studying the deformation dynamics and permeability evolution of rock systems. This is generally accompanied by fracture network characterization focusing on network topology that determines network connectivity. Fracture characterization allows to acquire quantitative and qualitative data on fractures and forms an important part of reservoir modeling. This thesis highlights the importance of fracture-healing and veins’ mechanical properties on the deformation dynamics. It shows that permeability varies spatially and temporally, and that healed systems (veined rocks) should not be treated as fractured systems (rocks without veins). Field observations also demonstrate the influence of contrasting mechanical properties, in addition to the complexities of vein microstructures that can form in low-porosity and permeability layered sequences. The thesis also presents graph theory as a characterization method to obtain statistical measures on evolving network connectivity. It also proposes what measures a good reservoir should have to exhibit potentially large permeability and robustness against healing. The results presented in the thesis can have applications for hydrocarbon and geothermal reservoir exploration, mining industry, underground waste disposal, CO2 injection or groundwater modeling.

Strong shift equivalence, algebraic K-theory, and isolating zero-dimensional dynamics on manifolds

We study the relations of shift equivalence and strong shift equivalence for matrices over a ring $\mathcal{R}$, and establish a connection between these relations and algebraic K-theory. We utilize this connection to obtain results in two areas where the shift and strong shift equivalence relations play an important role: the study of finite group extensions of shifts of finite type, and the Generalized Spectral Conjectures of Boyle and Handelman for nonnegative matrices over subrings of the real numbers. We show the refinement of the shift equivalence class of a matrix $A$ over a ring $\mathcal{R}$ by strong shift equivalence classes over the ring is classified by a quotient $NK_{1}(\mathcal{R}) / E(A,\mathcal{R})$ of the algebraic K-group $NK_{1}(\calR)$. We use the K-theory of non-commutative localizations to show that in certain cases the subgroup $E(A,\mathcal{R})$ must vanish, including the case $A$ is invertible over $\mathcal{R}$. We use the K-theory connection to clarify the structure of algebraic invariants for finite group extensions of shifts of finite type. In particular, we give a strong negative answer to a question of Parry, who asked whether the dynamical zeta function determines up to finitely many topological conjugacy classes the extensions by $G$ of a fixed mixing shift of finite type. We apply the K-theory connection to prove the equivalence of a strong and weak form of the Generalized Spectral Conjecture of Boyle and Handelman for primitive matrices over subrings of $\mathbb{R}$. We construct explicit matrices whose class in the algebraic K-group $NK_{1}(\mathcal{R})$ is non-zero for certain rings $\mathcal{R}$ motivated by applications. We study the possible dynamics of the restriction of a homeomorphism of a compact manifold to an isolated zero-dimensional set. We prove that for $n \ge 3$ every compact zero-dimensional system can arise as an isolated invariant set for a homeomorphism of a compact $n$-manifold. In dimension two, we provide obstructions and examples.

Expedition in Data and Harmonic Analysis on Graphs

The graph Laplacian operator is widely studied in spectral graph theory largely due to its importance in modern data analysis. Recently, the Fourier transform and other time-frequency operators have been defined on graphs using Laplacian eigenvalues and eigenvectors. We extend these results and prove that the translation operator to the i’th node is invertible if and only if all eigenvectors are nonzero on the i’th node. Because of this dependency on the support of eigenvectors we study the characteristic set of Laplacian eigenvectors. We prove that the Fiedler vector of a planar graph cannot vanish on large neighborhoods and then explicitly construct a family of non-planar graphs that do exhibit this property. We then prove original results in modern analysis on graphs. We extend results on spectral graph wavelets to create vertex-dyanamic spectral graph wavelets whose support depends on both scale and translation parameters. We prove that Spielman’s Twice-Ramanujan graph sparsifying algorithm cannot outperform his conjectured optimal sparsification constant. Finally, we present numerical results on graph conditioning, in which edges of a graph are rescaled to best approximate the complete graph and reduce average commute time.

A lower bound for the energy of symmetric matrices and graphs

The energy of a symmetric matrix is the sum of the absolute values of its eigenvalues. We introduce a lower bound for the energy of a symmetric partitioned matrix into blocks. This bound is related to the spectrum of its quotient matrix. Furthermore, we study necessary conditions for the equality. Applications to the energy of the generalized composition of a family of arbitrary graphs are obtained. A lower bound for the energy of a graph with a bridge is given. Some computational experiments are presented in order to show that, in some cases, the obtained lower bound is incomparable with the well known lower bound $2\sqrt{m}$, where $m$ is the number of edges of the graph.

Estudio y optimización de las infraestructuras de los carriles para bicicletas

La necesidad cotidiana de los ciudadanos de desplazarse para realizar diferentes actividades, sea cual fuere su naturaleza, se ha visto afectada en gran medida por los cambios producidos. Las ventajas generadas por la inclusión de la bicicleta como modo de transporte y la proliferación de su uso entre la ciudadanía son innumerables y se extienden tanto en el ámbito de la movilidad urbana como del desarrollo sostenible. En la actualidad, hay multitud de programas para la implantación, fomento o aumento de la participación ciudadana relacionado con la bicicleta en las ciudades. Pero en definitiva, todos y cada uno de estas iniciativas tienen la misma finalidad, crear una malla de vías cicladles eficaz y útil. Capaces de permitir el uso de la bicicleta en vías preferentes con unas garantías de seguridad altas, incorporando la bicicleta en el modelo de intermodalidad del transporte urbano. Con la progresiva implantación del carril bici, muchas personas han empezado a utilizarlas para moverse por la ciudad. Pero todo lo nuevo necesita un periodo de adaptación. Y, la realidad es que la red de viales destinados para estos vehículos está repleta de obstáculos para el ciclista. La actual situación ha llevado a cuestionar qué cantidad de kilómetros de carriles bici son necesarios para abastecer la demanda existente de este modo de transporte y, si las obras ejecutadas y proyectadas son las correctas y suficientes. En este trabajo se presenta una herramienta, basada en un modelo de programación matemática, para el diseño óptimo de una red destinada a los ciclistas. En concreto, el sistema determina una infraestructura para la bicicleta adaptada a las características de la red de carreteras existentes, con base en criterios de teoría de grafos ponderados. Como una aplicación del modelo propuesto, se ofrece el resultado de estos experimentos, obteniéndose un número de conclusiones útiles para la planificación y el diseño de redes de carriles bici desde una perspectiva social. Se realiza una aplicación de la metodología desarrollada para el caso real del municipio de Málaga (España). Por último se produce la validación del modelo de optimización presentado y la repercusión que tiene éste sobre el resultado final y la importancia o el peso del total de variables capaces de condicionar el resultado final de la red ciclista. Se obtiene, por tanto, una herramienta destinada a la mejora de la planificación, diseño y gestión de las diferentes infraestructuras para la bicicleta, con capacidad de interactuar con el modelo de red vial actual y con el resto de los modos de transportes existentes en el entramado urbano de las ciudades.

Gender theory and the family business

Gender Theory started in understanding and explain women's role in society and are also now including men and masculinities, Gender Theory has recently been adapted to family business research. This chapter will briefly introduce Gender Theory and its development, before reviewing how it has been used in family business research. Arguing that the family business context is suitable in studying gender phenomena, the chapter outlines several ways through which Gender Theory could yield new insights into issues, of how family business structures, settings and practices produce relations of power or asymmetry. A common approach so far to the study of gender in family business situations is to consider ‘gender as a variable’, which maintains the categorisation of women and men as a relevant and unproblematic variable. Many analyses of family businesses that also address gender focus on feminist ‘standpoint positions’, giving voice to women´s unique experiences. Often in family business research, the dominant approach is to conceive gender in terms of limited male/female distinctions rather than by reframing family business through critical positions, with the aim of reflection and sensitivity towards gender issues in terms of the socially constituted patterns that are produced through male/female, masculine/feminine distinctions. Concluding, the chapter suggests a possible methodology for capturing gendered processes and proposes how family business research could offer new insights into Gender theory.

Progresser dans la formation doctorale en sciences de l’humain et du social : individus et structure en tension

La présente thèse porte sur les enjeux de la progression dans la formation doctorale en sciences de l’humain et du social (SHS). Dans la plupart des pays occidentaux, les administrations universitaires se disent préoccupées par les délais d’achèvement et les faibles taux de diplomation au doctorat. S’il est admis que les aptitudes intellectuelles ne suffisent pas pour progresser dans les études doctorales, les recherches menées jusqu’ici montrent que les modalités de la formation, ainsi que le milieu et le contexte d’études dans lesquels celle-ci s’inscrit ont des répercussions sur l’expérience doctorale. Peu d’études portent toutefois sur la façon dont l’interaction de facteurs individuels et structurels peut affecter la progression dans ce processus de formation. En nous appuyant sur la théorie de la structuration de Giddens (2005), nous postulons dès lors que certaines valeurs, traditions et pratiques propres au monde académique – perpétuées, volontairement ou non, par les acteurs universitaires – peuvent nuire à la progression des doctorant-e-s. Afin d’examiner la question, une étude de cas instrumentale à visée compréhensive (Stake, 1994) a été réalisée. Six facultés des SHS d’une université canadienne ont été ciblées pour constituer le cas à l’étude. Outre l’analyse d’un ensemble de documents institutionnels relatif à la formation doctorale dans le contexte étudié, 36 doctorant-e-s issus de 19 disciplines ainsi que quatorze professeur-e-s et cinq administrateurs universitaires (directions de programmes/doyens/vices-doyens) ont été rencontrés dans le cadre d’entretiens semi-directifs. Nos résultats ont dans un premier temps permis de tracer un portrait descriptif détaillé du cas à l’étude. Les particularités de l’organisation formelle et tacite de la formation doctorale en SHS dans le contexte étudié ainsi que les défis qu’elle sous-tend ont été circonscrits, de même que les stratégies à privilégier – du point de vue des participant-e-s – pour progresser dans la formation. Dans un deuxième temps, il a été possible de montrer, d’une part, que c’est bien à la jonction de facteurs individuels et structurels que se situe la problématique de la progression dans la formation doctorale en SHS et des faibles taux de diplomation qui la caractérisent. D’autre part, la portée systémique d’une telle problématique a été mise au jour : à travers leurs choix, leurs attitudes et leurs pratiques, les acteurs universitaires contribuent à la reproduction de façon de faire et de penser « attendues » ou « admises » dans leur milieu, dont certaines ont le potentiel de nuire à la progression dans la formation doctorale.

Mathematics and fiber arts

Mathematics can be found all over the world, even in what could be considered an unrelated area, like fiber arts. In knitting, crochet, and counted-thread embroidery, we can find concepts of algebra, graph theory, number theory, geometry of transformations, and symmetry, as well as computer science. For example, many fiber art pieces embody notions related with groups of symmetry. In this work, we focus on two areas of Mathematics associated with knitting, crochet, and cross-stitch works – number theory and geometry of transformations.

Simplicial Complexes From Graphs Toward Graph Persistence

Persistent homology is a branch of computational topology which uses geometry and topology for shape description and analysis. This dissertation is an introductory study to link persistent homology and graph theory, the connection being represented by various methods to build simplicial complexes from a graph. The methods we consider are the complex of cliques, of independent sets, of neighbours, of enclaveless sets and complexes from acyclic subgraphs, each revealing several properties of the underlying graph. Moreover, we apply the core ideas of persistence theory in the new context of graph theory, we define the persistent block number and the persistent edge-block number.