Building the UPPA high capacity tensiometer

High capacity tensiometers (HCTs) are sensors capable of directly measuring tensile pore water pressure (suction) in soils. HCTs are typically composed of a casing that encapsulates a high air entry value ceramic filter, a water reservoir and a pressure sensing element. Since the creation of the first HCT by Ridley and Burland in 1993 at Imperial College London, HCTs have been almost exclusively built and used in academic research. The limited use in industrial applications can be explained by a lack of unsaturated soil mechanics knowledge among engineering practitioners but also by the technical difficulties associated to the direct measurement of tensile water pressures beyond the cavitation limit of -100kPa. In this paper, we present the recent design and manufacture of a new HCT at the Université de Pau et des Pays de l’Adour (UPPA) in France. Different prototypes were tried by changing the main components of the device including the type of ceramic filter, pressure transducer and geometry of the external casing. In particular, two ceramic filters of distinct porosity, three pressure transducers with distinct materials/geometries and four casing designs were tested

Advances in the monitoring of geo-structure subjected to climate loading

The paper presents results achieved within the project MAGIC, a project funded by the European Commission under the Marie-Curie Industry Academia Partnerships and Pathways (IAPP) scheme. The project MAGIC aims to advance the state-of-the art in the monitoring of geo-structures subjected to climate loading by filling some of the gaps in current monitoring technologies. The project involves a partnership between academic and industrial partners to boost knowledge transfer and promote the development of ‘industrial’ instruments and services. The paper presents developments concerning the measurement of pore-water tension (suction in excess of 100 kPa) and the integration of geotechnical and geophysical monitoring

Unity Through Diversity: A Case Study of Chrislam in Lagos

This article presents an ethnographic case study of Chrislam, a series of religious movements that fuse Christian and Muslim beliefs and practices, in its socio-cultural and political-economic setting in Nigeria’s former capital Lagos. Against conventional approaches to study religious movements in Africa as syncretic forms of ‘African Christianity’ or ‘African Islam’, I suggest that ‘syncretism’ is a misleading appellation for Chrislam. In fact, Chrislam provides a rationale for scrutinizing the very concept of syncretism and offers an alternative analytical case for understanding its mode of religious pluralism. To account for the religious plurality in Chrislam, I employ assemblage theory as it proposes novel ways for looking at Chrislam’s religious mixing that are in line with how its worshippers perceive their religiosity. The underlying idea in Chrislam’s assemblage of Christianity and Islam is that to be a Christian or Muslim alone is not enough to guarantee success in this world and the hereafter and therefore Chrislam worshippers partake in Christian as well as Muslim practices, appropriating the perceived powers of both

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Inhabiting Ocular Ground: Kinshasa's Future in the Light of Congo's Spectral Urban Politics

Uncorrected proof. Supplemental material: http://www.culanth.org/?q=node/384This article addresses the tensions that exist between the lives of city dwellers in Kinshasa, the capital of the Democratic Republic of Congo, and those official attempts currently being launched by the Congolese government to create a new, albeit exclusionist, urban environment. During the campaign leading up to the 2006 presidential elections, President Kabila launched his “Cinq Chantiers” program, arguably the most ambitious project since the end of colonization in 1960 to overhaul the country and respond to its most pressing and urgent needs—or at least that of its elites—with regard to its urbanization. The article first situates the main phases of Kinshasa’s expansion from the colonial era to the present day. It then turns to an analysis of the impact of the “Cinq Chantiers” program by examining two concrete cases: the expansion of fields in the Malebo Pool (looking at current modes of “informal” urban expansion into urban space) and the development of a new urban project, the Cité du Fleuve (whose progressive uplift leaves out a large swath of the population). Are these examples of an African futurity, and for whom (and whom not) do they envision a new kind of urban life

Building the UPPA high capacity tensiometer

High capacity tensiometers (HCTs) are sensors capable of directly measuring tensile pore water pressure (suction) in soils. HCTs are typically composed of a casing that encapsulates a high air entry value ceramic filter, a water reservoir and a pressure sensing element. Since the creation of the first HCT by Ridley and Burland in 1993 at Imperial College London, HCTs have been almost exclusively built and used in academic research. The limited use in industrial applications can be explained by a lack of unsaturated soil mechanics knowledge among engineering practitioners but also by the technical difficulties associated to the direct measurement of tensile water pressures beyond the cavitation limit of -100kPa. In this paper, we present the recent design and manufacture of a new HCT at the Université de Pau et des Pays de l’Adour (UPPA) in France. Different prototypes were tried by changing the main components of the device including the type of ceramic filter, pressure transducer and geometry of the external casing. In particular, two ceramic filters of distinct porosity, three pressure transducers with distinct materials/geometries and four casing designs were tested

Conditional mixed models with crossed random effects

The analysis of continuous hierarchical data such as repeated measures or data from meta-analyses can be carried out by means of the linear mixed-effects model. However, in some situations this model, in its standard form, does pose computational problems. For example, when dealing with crossed random-effects models, the estimation of the variance components becomes a non-trivial task if only one observation is available for each cross-classified level. Pseudolikelihood ideas have been used in the context of binary data with standard generalized linear multilevel models. However, even in this case the problem of the estimation of the variance remains non-trivial. In this paper we first propose a method to fit a crossed random-effects model with two levels and continuous outcomes, borrowing ideas from conditional linear mixed-effects model theory. We also propose a crossed random-effects model for binary data combining ideas of conditional logistic regression with pseudolikelihood estimation. We apply this method to a case study with data coming from the field of psychometrics and study a series of items (responses) crossed with participants. A simulation study assesses the operational characteristics of the method