Labour costs and queueing theory in retailing

In this paper approximation results for the M/G/s queueing model are used to derive an empirically verified shop type dependent non-homogeneous relation between labour volume and sales in retail trade. Moreover, we formulate the retailer's labour management as a formal minimization problem

Post-harvest handling practices and associated food losses and limitations in the sweetpotato value chain of southern Ethiopia

Household food insecurity is a chronic problem in Ethiopia; the situation is being exacerbated by high population growth rates and recurring droughts in the country. The interest to address post-harvest value chain (VC) constraints leading to food losses has increased significantly to provide adequate nutrition to the growing population. In this study, mapping of sweetpotato VC not only quantifies the degree of losses but establish links between distinct VC constraints and respective food losses and limitations. Harvest and handling at farm level and shelf life issues at distribution were identified as vulnerable hot-spots of the sweetpotato food losses. Apart from physical and biological factors, demand and supply mismatch during the main harvest season at the wet markets leads to food (up to 25%) and economic losses (33–75%) followed by deficiencies in the lean season. A multi-stakeholder cooperation is required to mitigate food losses, which can have a high impact on the nutritional and financial status of the producers, market operators, and the consumers

Self-employment and Health: Barriers or Benefits?

The self-employed are often reported to be healthier than wage workers; however, the cause of this health difference is largely unknown. The longitudinal nature of the US Health and Retirement Study allows us to gauge the plausibility of two competing explanations for this difference: a contextual, causal effect of self-employment on health (benefit effect), or a health-related selection of individuals into self-employment (barrier effect). Our main finding is that the selection of comparatively healthier individuals into self-employment accounts for the positive cross-sectional difference. The results rule out a positive contextual effect of self-employment on health, and we present tentative evidence that, if anything, engaging in self-employment is bad for one's health. Given the importance of the self-employed in the economy, these findings contribute to our understanding of the vitality of the labor force

Guidance for interpretation of CBD categories on introduction pathways

Technical note prepared by IUCN for the European Commission. This note has been drafted by a team of experts under the supervision of IUCN within the framework of the contract No 07.0202/2016/739524/SER/ENV.D.2 “Technical and Scientific support in relation to the Implementation of Regulation 1143/2014 on Invasive Alien Species”

A decade of research on the genetics of entrepreneurship: a review and view ahead

Studies analyzing the heritability of entrepreneurship indicate that explanations for why people engage in entrepreneurship that ignore genes are incomplete. However, despite promises that were solidly backed up with ex ante power calculations, atte

Overconfidence, optimism and entrepreneurship

Overconfidence is one of the alleged drivers for market entry. However, establishing its effect is challenging and much of the existing entrepreneurship literature confusingly conflates overconfidence with optimism. In the present study, we use validated scales to analyze the relationship between overconfidence and two important aspects of entrepreneurship, while explicitly controlling for optimism. Specifically, we study the role of overconfidence in developing intentions about entering entrepreneurship as well as how overconfidence relates to entrepreneurial orientation. Our findings show that overconfidence is related to intended market entry but not to the market position (entrepreneurial orientation) of the business

In Vivo Tracking and 1H/19F Magnetic Resonance Imaging of Biodegradable Polyhydroxyalkanoate / Polycaprolactone Blend Scaffolds Seeded with Labeled Cardiac Stem Cells

Medium-chain length Polyhydroxyalkanoates (MCL-PHAs) have demonstrated exceptional properties for cardiac tissue engineering (CTE) applications. Despite prior work on MCL-PHA/Polycaprolactone (PCL) blends, optimal scaffold production and use as an alternative delivery route for controlled release of seeded cardiac progenitor cells (CPCs) in CTE applications in vivo has been lacking, We present herein applicability of MCL-PHA/PCL (95/5 wt%) blends fabricated as thin films with an improved performance compared to the neat MCL-PHA aiming to a) benefit from the material properties of natural and synthetic polymers, b) achieve controlled delivery and increase retention of delivered cells to the murine myocardium, c) extend the temporal window over which the release of labeled CPCs occurs compared to traditional direct injection techniques, and d) use 19F MRI/MRS to noninvasively detect, and longitudinally monitor the seeded scaffolds. Polymer characterization confirmed the chemical structure and composition of the synthesized scaffolds, while thermal, wettability, and mechanical properties were also investigated and compared in neat and porous counterparts. In vitro cytocompatibility studies were performed using perfluorocrown-ether (PFCE)-nanoparticle-labeled murine cardiac progenitor cells (CPC), and studied using confocal microscopy and 19F MRS/MRI. Seeded scaffolds were implanted and studied in the post-mortem murine heart in situ, and in two additional C57BL/6 mice in vivo (using single-layered and double-layered scaffolds) and imaged immediately after and at 7 days post-implantation. Superior MCL-PHA/PCL scaffold performance has been demonstrated compared to MCL-PHA through experimental comparisons of a) morphological data using scanning electron microscopy and b) contact angle measurements attesting to improved CPC adhesion, c) in vitro confocal microscopy showing increased SC proliferative capacity, d) mechanical testing that elicited good overall responses. In vitro MRI results justify the increased seeding density, increased in vitro MRI signal, and improved MRI visibility in vivo, in the double-layered compared to the single-layered scaffolds. Histological evaluations (bright-field, cytoplasmic (Atto647) and nuclear (DAPI) stains) performed in conjunction with confocal microscopy imaging attest to CPC binding within the scaffold, subsequent release and migration to the neighboring myocardium, and to increased retention in the murine myocardium in the case of the double-layered scaffold. Thus MCL-PHA/PCL blends possess tremendous potential for controlled delivery of CPCs and to maximize possible regeneration in myocardial infarction