Environmental Water Related Deterioration of Compressed Stabilized Earth Block Structures in Uganda

The provision of shelter for all has not yet been realised. The main challenge is the high cost of building materials. Compressed and stabilised earth blocks (CSEB) are now recognised as low cost materials. While their green properties are well understood, the durability of these materials remain enigmatic. The objective of this research was to investigate the durability of CSEBs as used in the humid tropics. The interplay between the block and the effects of natural exposure conditions, especially the dynamics of rainfall, are examined. Through a methodology involving literature reviews, physical inspections, and exposure condition survey, block behaviour and defects over time are rigorously investigated. Water deterioration modes and their mechanisms of progression are discussed. The sources of water, agents, actions, effects, affected properties, and rate of deterioration are described. Defects were exhibited mainly as surface erosion, and cracking. However, it is still possible to improve the durability and wear resistance of CSEBs for use in the humid tropics. The improvement is achieved via lowered water absorption, and improved design codes, tests and standards. The findings are likely to contribute to the future widespread use of CSEBs. The findings raise a number of questions for further studies. Keywords: Compressed Earth Blocks, Deterioration, Durability, Rainfall, Soil-Cement, Stabilization, Wate

Exposure Condition Survey and Measurement of Defects in Compressed Stabilized Earth Block Structures in Uganda

Inadequate provision of shelter remains a global challenge. The high cost of building materials is responsible for this situation. The compressed and stabilised earth block (CSEB) has been promoted as a low cost material. While its other properties are well understood, the behaviour of the material over time has not been properly researched. The principal objective of this research was to investigate their in-service exposure and measure defects in a humid tropical environment. Such areas are characterised by extremes of weather. The soils are also varied. The paper examines the effects of natural exposure conditions on the deterioration of CSEBs. The methodology involved literature review, visual inspection, exposure condition survey, and measurement of defects. It was confirmed that premature deterioration was widespread in exposed structures, with visible defects. The paper recommends an urgent need for improvement in the production and use of CSEBs through dissemination of location specific appropriate specifications, standards and codes. It further proposes the need for improved protective measures in the humid tropics. Additional improvement can be achieved via better inter-granular bonding, reduction in voids, lowered water absorption, and protective designs and specifications. Hence, future challenges can be prevented and the effects of identified deterioration agents minimised. Keywords: Building Survey, Compressed Stabilised Earth Blocks, Defects, Exposure Condition, Structure

Naked bodies and collective action: repertoires of protest in Uganda’s militarised, authoritarian regime

How can citizens living under increasingly militarized and authoritarian regimes exercise political voice? Using an in-depth case study of naked protest in modern day Uganda, this article finds that naked bodies allow citizens to employ three types of overlapping power to confront a militarized authoritarian state: biopower, symbolic power, and cosmological power. The study illustrates one way in which citizens seek to engage militarized regimes—and in doing so, how political voice takes particular forms with limited capacity to instigate broader political claim-making that might be associated with country- or region-wide political action

Durability of compressed and cement-stabilised building blocks

Adequate shelter is a basic human need, yet about 80% of the urban population in developing countries still live in spontaneous settlements as they cannot afford the high cost of building materials. The compressed and stabilised block (CSB) has been identified as a low-cost material with the potential to redress the problem and reverse the shelter backlog. While its other properties are well understood, the durability of the material remains enigmatic. The principal objective of this research was therefore to investigate the durability of CSBs, especially as used in the humid tropics. The thesis examines the interplay between three main factors: constituent materials used (cement, soil, water); quality of block processing methods employed; and the effects of natural exposure conditions (physical, chemical, biological). Through a multi-pronged methodology involving literature reviews, laboratory experiments, petrographic analysis and an exposure condition survey, block properties and behaviour are rigorously investigated. The findings are presented under the two main division of the thesis: Part A and Part B. Part A introduces a review of the literature on the main theoretical concepts of durability and cement-soil stabilisation. It discusses various deterioration modes, and examines in more detail mechanisms of stabilisation using Ordinary Portland cement. Part A also identifies and highlights critical stages of the CSB production cycle, and recommends a strict adherence to proper testing and processing procedures. Part B presents the results of direct investigation methods used. Findings from the fieldwork confirmed that premature deterioration was widespread in exposed unrendered blocks, with defects exhibited mainly as surface erosion and cracking. Quality checks on site materials and practice established an urgent need for improvement through the provision of appropriate standards and codes. Laboratory experiments which compared the properties of traditional blocks (TDB) and blocks improved by the inclusion of micro silica (IPD), established that the latter significantly out-performed the former. A new quick predictive surface test, the slake durability test, which is more reliable and repeatable than existing tests, is proposed. The thesis concludes that it is possible to significantly raise the strength, improve the dimensional stability and wear resistance of CSBs to the extent that they can be safely used in unrendered walls in the humid tropics. This improvement is achieved via better intergranular bonding, reduction in voids and lowered absorption. Using the slake durability test, it is now tenable to freely discriminate, classify, and compare not only blocks but other like materials of any category and storage history as well. New quantitative durability gradings are recommended for future incorporation into CSB standards. The findings are likely to contribute to the widespread use of CSBs. The research, however, also raises a number of new questions which are listed for further work

Genomic analysis of the function of the transcription factor gata3 during development of the Mammalian inner ear

We have studied the function of the zinc finger transcription factor gata3 in auditory system development by analysing temporal profiles of gene expression during differentiation of conditionally immortal cell lines derived to model specific auditory cell types and developmental stages. We tested and applied a novel probabilistic method called the gamma Model for Oligonucleotide Signals to analyse hybridization signals from Affymetrix oligonucleotide arrays. Expression levels estimated by this method correlated closely (p<0.0001) across a 10-fold range with those measured by quantitative RT-PCR for a sample of 61 different genes. In an unbiased list of 26 genes whose temporal profiles clustered most closely with that of gata3 in all cell lines, 10 were linked to Insulin-like Growth Factor signalling, including the serine/threonine kinase Akt/PKB. Knock-down of gata3 in vitro was associated with a decrease in expression of genes linked to IGF-signalling, including IGF1, IGF2 and several IGF-binding proteins. It also led to a small decrease in protein levels of the serine-threonine kinase Akt2/PKB beta, a dramatic increase in Akt1/PKB alpha protein and relocation of Akt1/PKB alpha from the nucleus to the cytoplasm. The cyclin-dependent kinase inhibitor p27(kip1), a known target of PKB/Akt, simultaneously decreased. In heterozygous gata3 null mice the expression of gata3 correlated with high levels of activated Akt/PKB. This functional relationship could explain the diverse function of gata3 during development, the hearing loss associated with gata3 heterozygous null mice and the broader symptoms of human patients with Hearing-Deafness-Renal anomaly syndrome

The histone demethylase LSD1 regulates inner ear progenitor differentiation through interactions with Pax2 and the NuRD repressor complex

The histone demethylase LSD1 plays a pivotal role in cellular differentiation, particularly in silencing lineage-specific genes. However, little is known about how LSD1 regulates neurosensory differentiation in the inner ear. Here we show that LSD1 interacts directly with the transcription factor Pax2 to form the NuRD co-repressor complex at the Pax2 target gene loci in a mouse otic neuronal progenitor cell line (VOT-N33). VOT-N33 cells expressing a Pax2-response element reporter were GFP-negative when untreated, but became GFP positive after forced differentiation or treatment with a potent LSD inhibitor. Pharmacological inhibition of LSD1 activity resulted in the enrichment of mono- and di-methylation of H3K4, upregulation of sensory neuronal genes and an increase in the number of sensory neurons in mouse inner ear organoids. Together, these results identify the LSD1/NuRD complex as a previously unrecognized modulator for Pax2-mediated neuronal differentiation in the inner ear

Wnt Signaling Promotes Neuronal Differentiation from Mesenchymal Stem Cells Through Activation of Tlx3

Wnt/β-catenin signaling promotes neural differentiation by activation of the neuron-specific transcription factors, Neurogenin1 ( Ngn1 ), NeuroD , and Brn3a , in the nervous system. As neurons in cranial sensory ganglia and dorsal root ganglia transiently express Ngn1, NeuroD , and Brn3a during embryonic development, we hypothesized that Wnt proteins could instructively promote a sensory neuronal fate from mesenchymal stem cells (MSCs) directed to differentiate into neurons. Consistent with our hypothesis, Wnt1 induced expression of sensory neuron markers including Ngn1, NeuroD , and Brn3a , as well as glutamatergic markers in neurally induced MSCs in vitro and promoted engraftment of transplanted MSCs in the inner ear bearing selective loss of sensory neurons in vivo. Given the consensus function of T-cell leukemia 3 ( Tlx3 ), as a glutamatergic selector gene, we postulated that the effects of canonical Wnt signaling on sensory neuron and glutamatergic marker gene expression in MSCs may be mediated by Tlx3 . We first confirmed that Wnt1 indeed upregulates Tlx3 expression, which can be suppressed by canonical Wnt inhibitors. Next, our chromatin immunoprecipitation assays revealed that T-cell factor 3/4, Wnt-activated DNA binding proteins, interact with a regulatory region of Tlx3 in MSCs after neural induction. Furthermore, we demonstrated that forced expression of Tlx3 in MSCs induced sensory and glutamatergic neuron markers after neural induction. Together, these results identify Tlx3 as a novel target for canonical Wnt signaling that confers somatic stem cells with a sensory neuron phenotype upon neural induction. S TEM C ELLS 2011;29:836–846Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83767/1/624_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/83767/2/STEM_624_sm_suppinfoFigs.pd

Using the Tg(nrd:egfp)/albino Zebrafish Line to Characterize In Vivo Expression of neurod

In this study, we used a newly-created transgenic zebrafish, Tg(nrd:egfp)/albino, to further characterize the expression of neurod in the developing and adult retina and to determine neurod expression during adult photoreceptor regeneration. We also provide observations regarding the expression of neurod in a variety of other tissues. In this line, EGFP is found in cells of the developing and adult retina, pineal gland, cerebellum, olfactory bulbs, midbrain, hindbrain, neural tube, lateral line, inner ear, pancreas, gut, and fin. Using immunohistochemistry and in situ hybridization, we compare the expression of the nrd:egfp transgene to that of endogenous neurod and to known retinal cell types. Consistent with previous data based on in situ hybridizations, we show that during retinal development, the nrd:egfp transgene is not expressed in proliferating retinal neuroepithelium, and is expressed in a subset of retinal neurons. In contrast to previous studies, nrd:egfp is gradually re-expressed in all rod photoreceptors. During photoreceptor regeneration in adult zebrafish, in situ hybridization reveals that neurod is not expressed in Müller glial-derived neuronal progenitors, but is expressed in photoreceptor progenitors as they migrate to the outer nuclear layer and differentiate into new rod photoreceptors. During photoreceptor regeneration, expression of the nrd:egfp matches that of neurod. We conclude that Tg(nrd:egfp)/albino is a good representation of endogenous neurod expression, is a useful tool to visualize neurod expression in a variety of tissues and will aid investigating the fundamental processes that govern photoreceptor regeneration in adults