Constrained gazelles. High potentials in West Africa’s informal economy

The informal sector is typically characterised as being very heterogeneous and possibly composed of two clearly distinct segments, sometimes called the lower and upper tier. However, empirical evidence shows that even among lower tier entrepreneurs profitability can be quite high. We combine these findings and develop an innovative approach to identify what we call ‘constrained gazelles’, next to the well-known survivalists in the lower tier and growth-oriented top-performers in the upper tier. Our sample of informal entrepreneurs in seven West-African countries allows to link the relative size of these three groups to the structural and macroeconomic environment in these countries

Regional association of pCASL-MRI with FDG-PET and PiB-PET in people at risk for autosomal dominant Alzheimer's disease.

Autosomal dominant Alzheimer's disease (ADAD) is a small subset of Alzheimer's disease that is genetically determined with 100% penetrance. It provides a valuable window into studying the course of pathologic processes that leads to dementia. Arterial spin labeling (ASL) MRI is a potential AD imaging marker that non-invasively measures cerebral perfusion. In this study, we investigated the relationship of cerebral blood flow measured by pseudo-continuous ASL (pCASL) MRI with measures of cerebral metabolism (FDG PET) and amyloid deposition (Pittsburgh Compound B (PiB) PET). Thirty-one participants at risk for ADAD (age 39 ± 13 years, 19 females) were recruited into this study, and 21 of them received both MRI and FDG and PiB PET scans. Considerable variability was observed in regional correlations between ASL-CBF and FDG across subjects. Both regional hypo-perfusion and hypo-metabolism were associated with amyloid deposition. Cross-sectional analyses of each biomarker as a function of the estimated years to expected dementia diagnosis indicated an inverse relationship of both perfusion and glucose metabolism with amyloid deposition during AD development. These findings indicate that neurovascular dysfunction is associated with amyloid pathology, and also indicate that ASL CBF may serve as a sensitive early biomarker for AD. The direct comparison among the three biomarkers provides complementary information for understanding the pathophysiological process of AD

Constrained firms, not subsistence activities: evidence on capital returns and accumulation in Peruvian microenterprises

We investigate the returns to capital and capital accumulation using panel data of Peruvian micro enterprises (MEs). Marginal returns to capital are found to be very high at low levels of capital, but rapidly decreasing at higher levels. The dynamic analyses of capital accumulation in MEs suggest that credit constraints explain a major part of the variation in firm growth. We find a very large positive effect of household non-business wealth on capital stocks of MEs. We also show a sizable effect of risk on accumulation and pronounced interactions between wealth and risk. The presented evidence is consistent with poorly endowed entrepreneurs who operate in imperfect capital markets and a very risky environment

Credit‐constrained in risky activities? The determinants of the capital stocks of micro and mall firms in Western Africa

Micro and small enterprises (MSEs) in developing countries are typically considered to be severely credit constrained. Additionally, high business risks may partly explain why the capital stocks of MSEs remain low. This article analyzes the determinants of the capital stocks of MSEs in poor economies focusing on credit constraints and risk. The analysis is based on a unique, albeit cross-sectional but backward‐looking, micro data set on MSEs covering the economic capitals of seven West‐African countries. The main result is that capital market imperfections indeed seem to explain an important part of the variation in capital stocks in the early lifetime of MSEs. Furthermore, the analyses show that risk plays a key role in capital accumulation. Risk-averse individuals seem to adjust their initially low capital stocks upwards when enterprises grow older. MSEs in risky activities owned by wealthy individuals even seem to over-invest when they start their business and subsequently adjust capital stocks downwards. As other firms simultaneously suffer from capital shortages, such behavior may imply large inefficiencies

Credit-constrained in risky activities? The determinants of the capital stocks of micro and small firms in Western Africa

Micro and small enterprises (MSEs) in developing countries are typically considered to be severely credit constrained. Additionally, high business risks may partly explain why the capital stocks of MSEs remain low. This article analyzes the determinants of the capital stocks of MSEs in poor economies focusing on credit constraints and risk. The analysis is based on a unique, albeit cross‐sectional but backward‐looking, micro data set on MSEs covering the economic capitals of seven West‐African countries. The main result is that capital market imperfections indeed seem to explain an important part of the variation in capital stocks in the early lifetime of MSEs. Furthermore, the analyses show that risk plays a key role in capital accumulation. Risk‐averse individuals seem to adjust their initially low capital stocks upwards when enterprises grow older. MSEs in risky activities owned by wealthy individuals even seem to over‐invest when they start their business and subsequently adjust capital stocks downwards. As other firms simultaneously suffer from capital shortages, such behaviour may imply large inefficiencies

MARQUIS: A multiplex method for absolute quantification of peptides and posttranslational modifications

Absolute quantification of protein expression and posttranslational modifications by mass spectrometry has been challenging due to a variety of factors, including the potentially large dynamic range of phosphorylation response. To address these issues, we have developed MARQUIS—Multiplex Absolute Regressed Quantification with Internal Standards—a novel mass spectrometry-based approach using a combination of isobaric tags and heavy-labelled standard peptides, to construct internal standard curves for peptides derived from key nodes in signal transduction networks. We applied MARQUIS to quantify phosphorylation dynamics within the ​EGFR network at multiple time points following stimulation with several ligands, enabling a quantitative comparison of ​EGFR phosphorylation sites and demonstrating that receptor phosphorylation is qualitatively similar but quantitatively distinct for each ​EGFR ligand tested. MARQUIS was also applied to quantify the effect of ​EGFR kinase inhibition on glioblastoma patient-derived xenografts. MARQUIS is a versatile method, broadly applicable and extendable to multiple mass spectrometric platforms.United States-Israel Binational Science FoundationNational Institutes of Health (U.S.) (Grant U54 CA112967)National Institutes of Health (U.S.) (Grant R01 CA118705)National Institutes of Health (U.S.) (Grant R01 CA096504)Mayo Brain Tumor SPORE CA10896

Evaluating genetic traceability methods for captive bred marine fish and their applications in fisheries management and wildlife forensics

Growing demands for marine fish products is leading to increased pressure on already depleted wild populations and a rise in the aquaculture production. Consequently, more captive bred fish are released into the wild through accidental escape or deliberate restocking, stock enhancement and sea ranching programs. The increased mixing of captive bred fish with wild conspecifics may affect the ecological and/or genetic integrity of wild fish populations. From a fisheries management perspective unambiguous identification tools for captive bred fish will be highly valuable to manage risks. Additionally there is great potential to use these tools in wildlife forensics (i.e. tracing back escapees to their origin and determining mislabelling of seafood products). Using SNP data from captive bred and wild populations of Atlantic cod (Gadus morhua L.) and sole (Solea solea L.), we explored the efficiency of population and parentage assignment techniques for the identification and tracing of captive bred fish. Simulated and empirical data were used to correct for stochastic genetic effects. Overall, parentage assignment performed well when a large effective population size characterizes the broodstock and escapees originate from early generations of captive breeding. Consequently, parentage assignments are particularly useful from a fisheries management perspective to monitor the effects of deliberate releases of captive bred fish on wild populations. Population assignment proved to be more efficient after several generations of captive breeding, which makes it a useful method in forensic applications for well-established aquaculture species. We suggest the implementation of a case by case strategy when choosing the best method

Insight into the mechanism of modulated syntheses: in situ synchrotron diffraction studies on the formation of Zr-fumarate MOF

In this work, the formation of a Zr-based metal-organic framework (MOF), Zr-fumarate MOF (Zr-fum MOF), is studied in situ by energy-dispersive diffraction. The Zr-fum MOF can be synthesised in DMF as well as in water-based synthesis systems. In both cases, its formation requires modulation, i.e. a monocarboxylic acid which is used as the modulator has to be added to the synthesis mixture. In general, different mechanisms of modulation are possible, for example, deprotonation of the linker molecule (deprotonation modulation) or coordination modulation (wherein the molecules of the modulator compete with the linker molecules for the coordination sites at the inorganic building units). Independently of the specific mechanism, modulation often improves the reproducibility of the MOF synthesis and the crystallinity of the product and may be used to control crystal size and morphology. This study is the first to investigate the kinetics of modulated MOF syntheses with regard to coordination modulation. According to this concept, the addition of a modulator usually decelerates the reaction. Our kinetic investigations show that this is the case for the formation of Zr-fum MOF in the water-based synthesis with formic acid used as a modulator. On the contrary, the addition of formic acid to the DMF-based synthesis results in an accelerating effect. This unexpected effect can be attributed to a small amount of water present in formic acid. Correspondingly, the addition of water to the synthesis mixture also showed an accelerating effect. These investigations emphasise the subtle interplay of the different ingredients in a MOF synthesis. In the case of the Zr-fum MOF, both the modulator formic acid and the water content strongly affect the kinetics of crystallisation. Quantitative evaluation of the kinetic data using the Gualtieri equation provides additional insight into the mechanisms of coordination-modulated MOF formation reactions and excludes the idea of deprotonation modulation.DFG/Porous Metal–Organic Frameworks/1362DESY/I-2011055

Timber gridshells: beyond the drawing board

In March 2011, a week-long workshop that invited participation from all architecture and architectural technology students at Sheffield Hallam University, UK was organised with the objective of enhancing students’ thinking and experience by construction thinking. It was aimed at creating a sense of realness to realise a design project collectively. Timber was set as the material of exploration. The students had to make use of bending to design and create a timber gridshell structure. This made use of a quality traditionally felt to be a structural weakness of the material. To do this, students form-found non-mathematically and non-digitally using paper gridmats. This paper describes the aims, activity and outcome of the timber gridshell workshop as a way of preparing architects and technologists of the future and introducing the challenges of architectural design in terms of economics and construction process, aesthetics, effective communication and structural intuition by working with a given material – all important aspects in achieving effective architecture

Fetishism and the social value of objects.

The idea of the fetish has a particular presence in the writings of both Marx and Freud. It implies for these two theorists of the social, a particular form of relation between human beings and objects. In the work of both the idea of the fetish involves attributing properties to objects that they do not 'really' have and that should correctly be recognised as human. While Marx's account of fetishism addresses the exchange-value of commodities at the level of the economic relations of production, it fails to deal in any detail with the use-value or consumption of commodities. In contrast Freud's concept of the fetish as a desired substitute for a suitable sex object explores how objects are desired and consumed. Drawing on both Marx and Freud, Baudrillard breaks with their analyses of fetishism as demonstrating a human relation with unreal objects. He explores the creation of value in objects through the social exchange of sign values, showing how objects are fetishised in ostentation. This paper argues that while Baudrillard breaks with the realism characteristic of Marx's and Freud's analyses of fetishism, he does not go far enough in describing the social and discursive practices in which objects are used and sometimes transformed into fetishes. It is proposed that the fetishisation of objects involves an overdetermination of their social value through a discursive negotiation of the capacities of objects that stimulates fantasy and desire for them