P algorithm, a dramatic enhancement of the waterfall transformation

This document has been extended by "Towards a unification of waterfalls, standard and P algorithms", see http://hal-ensmp.archives-ouvertes.fr/hal-00835016.This document describes an efficient enhancement of the waterfall algorithm, a hierarchical segmentation algorithm defined from the watershed transformation. The first part of the document recalls the definition of the waterfall algorithm, its various avatars as well as its links with the geodesic reconstruction. The second part starts by analyzing the different shortcomings of the algorithm and introduces several strategies to palliate them. Two enhancements are presented, the first one named standard algorithm and the second one, P algorithm. The different properties of P algorithm are analyzed. This analysis is detailed in the last part of the document. The performances of the two algorithms, in particular, are addressed and their analogies with perception mechanisms linked to the brightness constancy phenomenon are discussed

Border Flows

Declining access to fresh water is one of the twenty-first century’s most pressing environmental and human rights challenges, yet the struggle for water is not a new cause. The 8,800-kilometer border dividing Canada and the United States contains more than 20 percent of the world’s total freshwater resources, and Border Flows traces the century-long effort by Canada and the United States to manage and care for their ecologically and economically shared rivers and lakes. Ranging across the continent, from the Great Lakes to the Northwest Passage to the Salish Sea, the histories in Border Flows offer critical insights into the historical struggle to care for these vital waters. From multiple perspectives, the book reveals alternative paradigms in water history, law, and policy at scales from the local to the transnational. Students, concerned citizens, and policymakers alike will benefit from the lessons to be found along this critical international border. With contributions by Andrea Charron, Alice Cohen, Dave Dempsey, Jerry Dennis, Colin A.M. Duncan, Matthew Evenden, James W. Feldman, Noah D. Hall, Lynne Heasley, Nancy Langston, Frédéric Lasserre, Daniel Macfarlane, Andrew Marcille, Jeremy Mouat, Emma S. Norman, Peter Starr, Joseph E. Taylor III, and Graeme Wyn

Island Rivers

Anthropologists have written a great deal about the coastal adaptations and seafaring traditions of Pacific Islanders, but have had much less to say about the significance of rivers for Pacific island culture, livelihood and identity. The authors of this collection seek to fill that gap in the ethnographic record by drawing attention to the deep historical attachments of island communities to rivers, and the ways in which those attachments are changing in response to various forms of economic development and social change. In addition to making a unique contribution to Pacific island ethnography, the authors of this volume speak to a global set of issues of immense importance to a world in which water scarcity, conflict, pollution and the degradation of riparian environments afflict growing numbers of people. Several authors take a political ecology approach to their topic, but the emphasis here is less on hydro-politics than on the cultural meaning of rivers to the communities we describe. How has the cultural significance of rivers shifted as a result of colonisation, development and nation-building? How do people whose identities are fundamentally rooted in their relationship to a particular river renegotiate that relationship when the river is dammed to generate hydro-power or polluted by mining activities? How do blockages in the flow of rivers and underground springs interrupt the intergenerational transmission of local ecological knowledge and hence the ability of local communities to construct collective identities rooted in a sense of place

Breast Cancer Analysis in DCE-MRI

Breast cancer is the most common women tumour worldwide, about 2 million new cases diagnosed each year (second most common cancer overall). This disease represents about 12% of all new cancer cases and 25% of all cancers in women. Early detection of breast cancer is one of the key factors in determining the prognosis for women with malignant tumours. The standard diagnostic tool for the detection of breast cancer is x-ray mammography. The disadvantage of this method is its low specificity, especially in the case of radiographically dense breast tissue (young or under-forty women), or in the presence of scars and implants within the breast. Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) has demonstrated a great potential in the screening of high-risk women for breast cancer, in staging newly diagnosed patients and in assessing therapy effects. However, due to the large amount of information, DCE-MRI manual examination is error prone and can hardly be inspected without the use of a Computer-Aided Detection and Diagnosis (CAD) system. Breast imaging analysis is made harder by the dynamical characteristics of soft tissues since any patient movements (such as involuntary due to breathing) may affect the voxel-by-voxel dynamical analysis. Breast DCE-MRI computer-aided analysis needs a pre-processing stage to identify breast parenchyma and reduce motion artefacts. Among the major issues in developing CAD for breast DCE-MRI, there is the detection and classification of lesions according to their aggressiveness. Moreover, it would be convenient to determine those subjects who are likely to not respond to the treatment so that a modification may be applied as soon as possible, relieving them from potentially unnecessary or toxic treatments. In this thesis, an automated CAD system is presented. The proposed CAD aims to support radiologist in lesion detection, diagnosis and therapy assessment after a suitable preprocessing stage. Segmentation of breast parenchyma has been addressed relying on fuzzy binary clustering, breast anatomical priors and morphological refinements. The breast mask extraction module combines three 2D Fuzzy C-Means clustering (executed from the three projection, axial, coronal and transversal) and geometrical breast anatomy characterization. In particular, seven well-defined key-points have been considered in order to accurately segment breast parenchyma from air and chest-wall. To diminish the effects of involuntary movement artefacts, it is usual to apply a motion correction of the DCE-MRI volumes before of any data analysis. However, there is no evidence that a single Motion Correction Technique (MCT) can handle different deformations - small or large, rigid or non-rigid - and different patients or tissues. Therefore, it would be useful to develop a quality index (QI) to evaluate the performance of different MCTs. The existent QI might not be adequate to deal with DCE-MRI data because of the intensity variation due to contrast media. Therefore, in developing a novel QI, the underlying idea is that once DCE-MRI data have been realigned using a specific MCT, the dynamic course of the signal intensity should be as close as possible to physiological models, such as the currently accepted ones (e.g. Tofts-Kermode, Extended Tofts-Kermode, Hayton-Brady, Gamma Capillary Transit Time, etc.). The motion correction module ranks all the MCTs, using the QI, selects the best MCT and applies a correction before of further data analysis. The proposed lesion detection module performs the segmentation of lesions in Regions of Interest (ROIs) by means of classification at a pixel level. It is based on a Support Vector Machine (SVM) trained with dynamic features, extracted from a suitably pre-selected area by using a pixel-based approach. The pre-selection mask strongly improves the final result. The lesion classification module evaluates the malignity of each ROI by means of 3D textural features. The Local Binary Patterns descriptor has been used in the Three Orthogonal Planes (LBP-TOP) configuration. A Random Forest has been used to achieve the final classification into a benignant or malignant lesion. The therapy assessment stage aims to predict the patient primary tumour recurrence to support the physician in the evaluation of the therapy effects and benefits. For each patient which has at least a malignant lesion, the recurrence of the disease has been evaluated by means of a multiple classifiers system. A set of dynamic, textural, clinicopathologic and pharmacokinetic features have been used to assess the probability of recurrence for the lesions. Finally, to improve the usability of the proposed work, we developed a framework for tele-medicine that allows advanced medical image remote analysis in a secure and versatile client-server environment, at a low cost. The benefits of using the proposed framework will be presented in a real-case scenario where OsiriX, a wide-spread medical image analysis software, is allowed to perform advanced remote image processing in a simple manner over a secure channel. The proposed CAD system have been tested on real breast DCE-MRI data for the available protocols. The breast mask extraction stage shows a median segmentation accuracy and Dice similarity index of 98% (+/-0,49) and 93% %(+/-1,48) respectively and 100% of neoplastic lesion coverage. The motion correction module is able to rank the MCTs with an accordance of 74% with a 'reference ranking'. Moreover, by only using 40% of the available volume, the computational load is reduced selecting always the best MCT. The automatic detection maximises the area of correctly detected lesions while minimising the number of false alarms with an accuracy of 99% and the lesions are, then, diagnosed according to their stage with an accuracy of 85%. The therapy assessment module provides a forecasting of the tumour recurrence with an accuracy of 78% and an AUC of 79%. Each module has been evaluated by a leave-one-patient-out approach, and results show a confidence level of 95% (p<0.05). Finally, the proposed remote architecture showed a very low transmission overhead which settles on about 2.5% for the widespread 10\100 Mbps. Security has been achieved using client-server certificates and up-to-date standards

River flow monitoring: LS-PIV technique, an image-based method to assess discharge

The measurement of the river discharge within a natural ort artificial channel is still one of the most challenging tasks for hydrologists and the scientific community. Although discharge is a physical quantity that theoretically can be measured with very high accuracy, since the volume of water flows in a well-defined domain, there are numerous critical issues in obtaining a reliable value. Discharge cannot be measured directly, so its value is obtained by coupling a measurement of a quantity related to the volume of flowing water and the area of a channel cross-section. Direct measurements of current velocity are made, traditionally with instruments such as current meters. Although measurements with current meters are sufficiently accurate and even if there are universally recognized standards for the current application of such instruments, they are often unusable under specific flow conditions. In flood conditions, for example, due to the need for personnel to dive into the watercourse, it is impossible to ensure adequate safety conditions to operators for carrying out flow measures. Critical issue arising from the use of current meters has been partially addressed thanks to technological development and the adoption of acoustic sensors. In particular, with the advent of Acoustic Doppler Current Profilers (ADCPs), flow measurements can take place without personnel having direct contact with the flow, performing measurements either from the bridge or from the banks. This made it possible to extend the available range of discharge measurements. However, the flood conditions of a watercourse also limit the technology of ADCPs. The introduction of the instrument into the current with high velocities and turbulence would put the instrument itself at serious risk, making it vulnerable and exposed to damage. In the most critical case, the instrument could be torn away by the turbulent current. On the other hand, considering smaller discharges, both current meters and ADCPs are technologically limited in their measurement as there are no adequate water levels for the use of the devices. The difficulty in obtaining information on the lowest and highest values of discharge has important implications on how to define the relationships linking flows to water levels. The stage-discharge relationship is one of the tools through which it is possible to monitor the flow in a specific section of a watercourse. Through this curve, a discharge value can be obtained from knowing the water stage. Curves are site-specific and must be continuously updated to account for changes in geometry that the sections for which they are defined may experience over time. They are determined by making simultaneous discharge and stage measurements. Since instruments such as current meters and ADCPs are traditionally used, stage-discharge curves suffer from instrumental limitations. So, rating curves are usually obtained by interpolation of field-measured data and by extrapolate them for the highest and the lowest discharge values, with a consequent reduction in accuracy. This thesis aims to identify a valid alternative to traditional flow measurements and to show the advantages of using new methods of monitoring to support traditional techniques, or to replace them. Optical techniques represent the best solution for overcoming the difficulties arising from the adoption of a traditional approach to flow measurement. Among these, the most widely used techniques are the Large-Scale Particle Image Velocimetry (LS-PIV) and the Large-Scale Particle Tracking Velocimetry. They are able to estimate the surface velocity fields by processing images representing a moving tracer, suitably dispersed on the liquid surface. By coupling velocity data obtained from optical techniques with geometry of a cross-section, a discharge value can easily be calculated. In this thesis, the study of the LS-PIV technique was deepened, analysing the performance of the technique, and studying the physical and environmental parameters and factors on which the optical results depend. As the LS-PIV technique is relatively new, there are no recognized standards available for the proper application of the technique. A preliminary numerical analysis was conducted to identify the factors on which the technique is significantly dependent. The results of these analyses enabled the development of specific guidelines through which the LS-PIV technique could subsequently be applied in open field during flow measurement campaigns in Sicily. In this way it was possible to observe experimentally the criticalities involved in applying the technique on real cases. These measurement campaigns provided the opportunity to carry out analyses on field case studies and structure an automatic procedure for optimising the LS-PIV technique. In all case studies it was possible to observe how the turbulence phenomenon is a worsening factor in the output results of the LS-PIV technique. A final numerical analysis was therefore performed to understand the influence of turbulence factor on the performance of the technique. The results obtained represent an important step for future development of the topic

A Field Investigation For The Wind Load Performance Of Vegetated Greenroofs Using Monitoring Systems

Greenroof systems have been shown to be an environmentally friendly alternative based on various factors; such as, reduced lifecycle cost, improved air quality, ambient temperature reduction, stormwater management credit, sustainability and preservation of the environment. Recent research studies attempt to determine the construction methods of an ideal greenroof for environmental purposes, yet there is an absence of standards for the best design required to achieve acceptable structural performance and sustainability under wind loads. As a result, there is a need to document the effectiveness of greenroofs under high wind events by addressing the following questions: Do winds have an effect on greenroof material loss? Do greenroof materials modify local pressure conditions that would need a modification to current design codes? Does the level of vegetation establishment affect the material loss and pressure distribution? This thesis first focuses on vegetated greenroof construction techniques and issues along with some of the most recent studies conducted by UCF researchers. Then, the literature focuses on wind uplift of vegetated roofs constructed using different wind erosion control methods with respect to vegetation cover, geosynthetic liners, and wind breaks. As part of this research, two monitoring systems with a grid of very low differential pressure transducers and a high speed anemometer were designed and implemented on the East and West coasts of Florida to collect data for the pressure distribution across the greenroofs in relation to wind direction and speed. In addition to this, the design of this monitoring system with specific information about the sensing and data acquisition systems is presented. Subsequently, the analysis of the monitoring data compares the peak wind gusts for each time interval to their corresponding pressure measurement to obtain pressure coefficients identified at each pressure node on the roof. Based on this analysis, pressure changes for hurricane speed winds are predicted to have an overall average uplift pressure envelope within ASCE Code 7-05 design standards with vegetation cover enhancing sustainability under wind events. For future studies, controlled field investigations to reduce in situ limitations due to natural climatic conditions as well as long term monitoring are discussed as recommended studies for the evaluation of wind effects

Oak Thorn Kin: embodied practices of reciprocal restoration

This narrative nonfiction enacts and troubles the writing of wild places, as I move between an 'uninhabited’ landscape in the Scottish Highlands and urban parks, community gardens and nature reserves of Glasgow. Weaving a creativecritical path through environmental literature, feminist materialisms, and woodland ecology, it questions what ecological restoration means within the messiness of the Anthropocene, and how this implicates cultural, societal, and personal change. In this UN declared decade of ecological restoration, large scale conservation efforts, and in particular tree planting schemes, risk negating sensitivity to places and peoples through the urgency to sequester carbon, while biodiversity loss is treated separately from matters of social justice. The scientific discipline of ecological restoration is a process enacted on habitats and ecosystems, yet it holds potential to be collaborative and reciprocal. Using a practice-as-research approach, the event of becoming the resident of Airigh Drishaig— a woodland and cottage four miles from the nearest settlement or road— becomes an experiential study of reciprocal restoration. Bringing situated knowledge and feminist materialisms into relation with restoration epistemologies, the emphasis on more-than-human perspectives, lively matter and multi-agential movements allows for embodied practices to evolve in relationship with place. Walking, foraging, salvaging, coppicing, seed collection, seed dispersal and mapping become ways of connecting this fragment of ancient woodland to the larger story of how our ecological selves-in-relation (Plumwood) might respond to climate and biodiversity breakdown. The writing follows an arboreal rhythm of growth and decomposition over a three-year period of fieldwork, enfolding multiple temporalities of the landscape into the text. As a former shieling site, Airigh Drishaig is shaped by patterns of transhumance, while the undercurrents of petrochemical industries and intensive aquaculture force confrontation with extractivism. Reciprocal restoration relates to former land practices, while enfolding the embodied experience and reimagining ecological futures. Rather than a human imposed solutionism, it emerges through processes of entanglement, including loss as well as regeneration, and which crucially, allows for creative learning and coliving within the multi-agential re-storying of landscapes