Collaboration and competition:Market queens, trade unions and collective action of informal workers in Ghana’s Makola Market

This paper focuses on informal workers in Makola Market, Accra (Ghana), and the ways in which they organize for collective action. Ghana has a long history of trade and this makes for well-developed and culturally embedded local institutions that have organized and represented the (informal) workersactive in markets. A prominent example is the market queens, who (cl)aim to oversee, protect and promote markets vis-a-vis the public and the (municipal) government. Yet, these social structures are not easily recognized as a kind of social movement by (inter)national trade unions. Hence trade unioninterventions and outreaches aimed at ameliorating the plight of informal workers tend to bypass and antagonize these existing formations, fuelling competition and division in the already fragmented and inherently competitive market space. Based on 2.5 year-long ethnographic research on strategic actors in inclusive development with a focus on informal workers, this article draws attention to empirical realities in Ghana. It demonstrates that bypassing culturally embedded groups is problematic because it feeds fragmentation and thus limits the possibilities for collective action

Book review:Cooking Data: Culture & Politics in an African Research World

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An Analysis of the Representations of the Mapping Class Group of a Multi-Geon Three-Manifold

It is well known that the inequivalent unitary irreducible representations (UIR's) of the mapping class group $G$ of a 3-manifold give rise to ``theta sectors'' in theories of quantum gravity with fixed spatial topology. In this paper, we study several families of UIR's of $G$ and attempt to understand the physical implications of the resulting quantum sectors. The mapping class group of a three-manifold which is the connected sum of $\R^3$ with a finite number of identical irreducible primes is a semi-direct product group. Following Mackey's theory of induced representations, we provide an analysis of the structure of the general finite dimensional UIR of such a group. In the picture of quantized primes as particles (topological geons), this general group-theoretic analysis enables one to draw several interesting qualitative conclusions about the geons' behavior in different quantum sectors, without requiring an explicit knowledge of the UIR's corresponding to the individual primes.Comment: 52 pages, harvmac, 2 postscript figures, epsf required. Added an appendix proving the semi-direct product structure of the MCG, corrected an error in the characterization of the slide subgroup, reworded extensively. All our analysis and conclusions remain as befor

Bringing the state back in to humanitarian crises response:Disaster governance and challenging collaborations in the 2015 Malawi flood response

Malawi is a disaster-prone country with a long history of flooding. Yet disaster response policies have been largely neglected and disaster risk reduction efforts are mostly donor-led. The 2015 floods showed that Malawi's local and national state institutions struggled to respond adequately. To support the Malawi government, the United Nations implemented its cluster system to coordinate the collaborations between the state, humanitarian and nongovernmental organizations in the disaster response. Based on ethnographic fieldwork and interviews with relief intervention participants, we argue that a focus on the localization of aid without explicit attention to the affected state's institutions is problematic in contexts characterized by limited state capacity and overall donor dependency

Enhancing magneto-optic effects in two-dimensional magnets by thin-film interference

The magneto-optic Kerr effect is a powerful tool for measuring magnetism in thin films at microscopic scales, as was recently demonstrated by the major role it played in the discovery of two-dimensional (2D) ferromagnetism in monolayer CrI$_3$ and Cr$_2$Ge$_2$Te$_6$. These 2D magnets are often stacked with other 2D materials in van der Waals heterostructures on a SiO$_2$/Si substrate, giving rise to thin-film interference. This can strongly affect magneto-optical measurements, but is often not taken into account in experiments. Here, we show that thin-film interference can be used to engineer the magneto-optical signals of 2D magnetic materials and optimize them for a given experiment or setup. Using the transfer matrix method, we analyze the magneto-optical signals from realistic systems composed of van der Waals heterostructures on SiO$_2$/Si substrates, using CrI$_3$ as a prototypical 2D magnet, and hexagonal boron nitride (hBN) to encapsulate this air-sensitive layer. We observe a strong modulation of the Kerr rotation and ellipticity, reaching several tens to hundreds of milliradians, as a function of the illumination wavelength, and the thickness of the SiO$_2$ and layers composing the van der Waals heterostructure. Similar results are obtained in heterostructures composed by other 2D magnets, such as CrCl$_3$, CrBr$_3$ and Cr$_2$Ge$_2$Te$_6$. Designing samples for the optimal trade-off between magnitude of the magneto-optical signals and intensity of the reflected light should result in a higher sensitivity and shorter measurement times. Therefore, we expect that careful sample engineering, taking into account thin-film interference effects, will further the knowledge of magnetization in low-dimensional structures.Comment: manuscript: 12 pages, 4 figures. supplementary material: 22 pages, 20 figure

Properties of 3-manifolds for relativists

In canonical quantum gravity certain topological properties of 3-manifolds are of interest. This article gives an account of those properties which have so far received sufficient attention, especially those concerning the diffeomorphism groups of 3-manifolds. We give a summary of these properties and list some old and new results concerning them. The appendix contains a discussion of the group of large diffeomorphisms of the $l$-handle 3-manifold.Comment: 20 pages. Plain-TeX, no figures, 1 Table (A4 format

Fraught with friction:Inclusive development for informal workers in urban Ghana

Informal workers are a heterogeneous group distinguished by diverse activities and interests, but they have in common that they operate largely outside state regulations. In this article, we analyse the ways in which informal workers in Ghana are organising (themselves) in response to proposed relocations of their workspace. Borrowing from Tsing, we distinguish three layers of friction that can lead to (structural) change, collective action, and an increase in informal workers' political leverage. Our two case studies in Accra and Kumasi show how striving for inclusive development is a process shaped by diverse agendas and potentially conflicting interests. These relational and political aspects are crucial for understanding the frictions involved, as well as how these may lead to change. Where the tendency is to gloss over these frictions, we argue that they need to be the starting point for effective policies and initiatives for inclusive development

Three-dimensional morphology and gene expression in the Drosophila blastoderm at cellular resolution II: dynamics.

BackgroundTo accurately describe gene expression and computationally model animal transcriptional networks, it is essential to determine the changing locations of cells in developing embryos.ResultsUsing automated image analysis methods, we provide the first quantitative description of temporal changes in morphology and gene expression at cellular resolution in whole embryos, using the Drosophila blastoderm as a model. Analyses based on both fixed and live embryos reveal complex, previously undetected three-dimensional changes in nuclear density patterns caused by nuclear movements prior to gastrulation. Gene expression patterns move, in part, with these changes in morphology, but additional spatial shifts in expression patterns are also seen, supporting a previously proposed model of pattern dynamics based on the induction and inhibition of gene expression. We show that mutations that disrupt either the anterior/posterior (a/p) or the dorsal/ventral (d/v) transcriptional cascades alter morphology and gene expression along both the a/p and d/v axes in a way suggesting that these two patterning systems interact via both transcriptional and morphological mechanisms.ConclusionOur work establishes a new strategy for measuring temporal changes in the locations of cells and gene expression patterns that uses fixed cell material and computational modeling. It also provides a coordinate framework for the blastoderm embryo that will allow increasingly accurate spatio-temporal modeling of both the transcriptional control network and morphogenesis