Pistons modeled by potentials

In this article we consider a piston modelled by a potential in the presence of extra dimensions. We analyze the functional determinant and the Casimir effect for this configuration. In order to compute the determinant and Casimir force we employ the zeta function scheme. Essentially, the computation reduces to the analysis of the zeta function associated with a scalar field living on an interval $[0,L]$ in a background potential. Although, as a model for a piston, it seems reasonable to assume a potential having compact support within $[0,L]$, we provide a formalism that can be applied to any sufficiently smooth potential.Comment: 10 pages, LaTeX. A typo in eq. (3.5) has been corrected. In "Cosmology, Quantum Vacuum and Zeta Functions: In Honour of Emilio Elizalde", Eds. S.D. Odintsov, D. Saez-Gomez, and S. Xambo-Descamps. (Springer 2011) pp 31

Digital transformations and the archival nature of surrogates

Large-scale digitization is generating extraordinary collections of visual and textual surrogates, potentially endowed with transcendent long-term cultural and research values. Understanding the nature of digital surrogacy is a substantial intellectual opportunity for archival science and the digital humanities, because of the increasing independence of surrogate collections from their archival sources. The paper presents an argument that one of the most significant requirements for the long-term access to collections of digital surrogates is to treat digital surrogates as archival records that embody traces of their fluid lifecycles and therefore are worthy of management and preservation as archives. It advances a theory of the archival nature of surrogacy founded on longstanding notions of archival quality, the traces of their source and the conditions of their creation, and the functional ‘‘work of the archive.’’ The paper presents evidence supporting a ‘‘secondary provenance’’ derived from re-digitization, re-ingestion of multiple versions, and de facto replacement of the original sources. The design of the underlying research that motivates the paper and summary findings are reported separately. The research has been supported generously by the US Institute of Museum and Library Services.Institute for Museum and Library ServicesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111825/1/J26 Conway Digital Transformations 2014-pers.pdfDescription of J26 Conway Digital Transformations 2014-pers.pdf : Main articl

Response to issues on GM agriculture in Africa: Are transgenic crops safe?

The controversies surrounding transgenic crops, often called Genetically Modified Organisms (GMOs), call for a need to raise the level of public awareness of Genetic Modification (GM) technology in Africa. This should be accomplished by educating the public about the potential benefits and risks that may be associated with this new technology. In the last 15 years, GM crop producing countries have benefited from adoption of this new technology in the form of improved crop productivity, food security, and quality of life. The increased income to resource-poor farmers is a key benefit at the individual level especially as most countries using this technology are in the developing world, including three African countries (South Africa, Burkina Faso and Egypt). Despite clear benefits to countries and farmers who grow GMOs, many people are concerned about suspected potential risks associated with GMOs. This sparks debate as to whether GM technology should be adopted or not. Given the concerns regarding the safety of GMO products, thorough scientific investigation of safe application of GMOs is required. The objective of this paper is to respond to the issues of GM agriculture in Africa and some of the issues surrounding the adoption of GM crops between developed and developing countries. In this article, I analyse relevant papers relating to the adoption of GM technology particularly in developing countries including the few African countries that have adopted GM crops. The issues discussed span a wide range including: safety; potential benefits and risks; disputes between the United States of America (USA) and the European Union (EU) over adoption of GM crops with a focus on Africa continent. This article is concluded by summarising the issues raised and how GM technology can be adopted for agricultural development in Africa

Reproductive medicine in northwest Argentina: traditional and institutional systems

<p>Abstract</p> <p>Background</p> <p>The state of conservation of the traditional cultures of Northwest Argentina is variable and somewhat problematic but to a lesser or a greater extent all the peoples are related to an hegemonic culture. We present a case study carried out in the rural communities of the Yungas biome (Salta) where the extent of isolation varies as does the type of access to public health services. The use of medicinal plants in the area is ordinary and widely spread.</p> <p>Methods</p> <p>The data can be organized in two categories, as medical systems public records (for the regional hospital at Los Toldos), and as ethnobotanical sets. A total of 59 surveys to 40 interviewees were undertaken using a semi structured questionnaire. We present an analysis of the relative importance of the medicinal herbs used in reproductive medicine considering the plants used in the traditional medical system and the factors that can affect the relationship between formal medicine and patients. We further analized how the degree of accessibility to the local hospital influences the diversity of use of plant species used to assist deliveries and to decrease infant mortality in children minor than one year of age.</p> <p>Results</p> <p>In reproductive medicine, 13 ailments and/or different physiological states are locally identified and treated. Local population uses 108 ethnospecies for this kind of illnesses. According to the local conception the hot/cold imbalance could be the principal cause for reproductive illnesses; pregnancy may have natural or supernatural origin, post partum and menstruation involve similar sanitary risks, and neonatal care has a strong magic connotation. In relation with the formal medicine, the more accessible is the health center the more women assist to it. We have not found a relation between accessibility and infant mortality.</p> <p>Conclusion</p> <p>In the local reproductive medicine, most of the practices are concerned with the hot/cold balance. According to their importance the factors involved are: the family medicine, the midwife, and the formal doctors. Plants have an important role; however there is a lack of total agreement among the families who use them. Reluctance to institutional deliveries may be due to the weak relationship between patients and doctors, and the lack of logistic assistance to delivering mothers coming from far away locations.</p

Deletion of methylglyoxal synthase gene (mgsA) increased sugar co-metabolism in ethanol-producing Escherichia coli

The use of lignocellulose as a source of sugars for bioproducts requires the development of biocatalysts that maximize product yields by fermenting mixtures of hexose and pentose sugars to completion. In this study, we implicate mgsA encoding methylglyoxal synthase (and methylglyoxal) in the modulation of sugar metabolism. Deletion of this gene (strain LY168) resulted in the co-metabolism of glucose and xylose, and accelerated the metabolism of a 5-sugar mixture (mannose, glucose, arabinose, xylose and galactose) to ethanol

Whole genome resequencing of the human parasite Schistosoma mansoni reveals population history and effects of selection

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. The attached file is the published version of the article

Swift trust and commitment: the missing links for humanitarian supply chain coordination?

Coordination among actors in a humanitarian relief supply chain decides whether a relief operation can be or successful or not. In humanitarian supply chains, due to the urgency and importance of the situation combined with scarce resources, actors have to coordinate and trust each other in order to achieve joint goals. This paper investigated empirically the role of swift trust as mediating variable for achieving supply chain coordination. Based on commitment-trust theory we explore enablers of swift-trust and how swift trust translates into coordination through commitment. Based on a path analytic model we test data from the National Disaster Management Authority of India. Our study is the first testing commitment-trust theory (CTT) in the humanitarian context, highlighting the importance of swift trust and commitment for much thought after coordination. Furthermore, the study shows that information sharing and behavioral uncertainty reduction act as enablers for swift trust. The study findings offer practical guidance and suggest that swift trust is a missing link for the success of humanitarian supply chains

β-hairpin-mediated formation of structurally distinct multimers of neurotoxic prion peptides

Protein misfolding disorders are associated with conformational changes in specific proteins, leading to the formation of potentially neurotoxic amyloid fibrils. During pathogenesis of prion disease, the prion protein misfolds into β-sheet rich, protease-resistant isoforms. A key, hydrophobic domain within the prion protein, comprising residues 109–122, recapitulates many properties of the full protein, such as helix-to-sheet structural transition, formation of fibrils and cytotoxicity of the misfolded isoform. Using all-atom, molecular simulations, it is demonstrated that the monomeric 109–122 peptide has a preference for α-helical conformations, but that this peptide can also form β-hairpin structures resulting from turns around specific glycine residues of the peptide. Altering a single amino acid within the 109–122 peptide (A117V, associated with familial prion disease) increases the prevalence of β-hairpin formation and these observations are replicated in a longer peptide, comprising residues 106–126. Multi-molecule simulations of aggregation yield different assemblies of peptide molecules composed of conformationally-distinct monomer units. Small molecular assemblies, consistent with oligomers, comprise peptide monomers in a β-hairpin-like conformation and in many simulations appear to exist only transiently. Conversely, larger assemblies are comprised of extended peptides in predominately antiparallel β-sheets and are stable relative to the length of the simulations. These larger assemblies are consistent with amyloid fibrils, show cross-β structure and can form through elongation of monomer units within pre-existing oligomers. In some simulations, assemblies containing both β-hairpin and linear peptides are evident. Thus, in this work oligomers are on pathway to fibril formation and a preference for β-hairpin structure should enhance oligomer formation whilst inhibiting maturation into fibrils. These simulations provide an important new atomic-level model for the formation of oligomers and fibrils of the prion protein and suggest that stabilization of β-hairpin structure may enhance cellular toxicity by altering the balance between oligomeric and fibrillar protein assemblies