Review of The Undiscovered C. S. Lewis: Essays in Memory of Christopher W. Mitchell

Review of Bruce R. Johnson, ed., The Undiscovered C. S. Lewis: Essays in Memory of Christopher W. Mitchell (Hamden, CT: Winged Lion Press, 2021). 389 pages. $24.99. ISBN 978193568813

Mechanisms by which circadian rhythm disruption may lead to cancer

Humans have evolved in a rhythmic environment and display daily (circadian) rhythms in physiology, metabolism and behaviour that are in synchrony with the solar day. Modern lifestyles have compromised the exposure to bright light during the day and dark nights, resulting in the desynchronisation of endogenously generated circadian rhythms from the external environment and loss of coordination between rhythms within the body. This has detrimental effects on physical and mental health, due to the misregulation and uncoupling of important cellular and physiological processes. Long-term shift workers who are exposed to bright light at night experience the greatest disruption of their circadian rhythms. Studies have shown an association between exposure to light at night, circadian rhythm disruption and an increased risk of cancer. Previous reviews have explored the relevance of light and melatonin in cancer, but here we explore the correlation of circadian rhythm disruption and cancer in terms of molecular mechanisms affecting circadian gene expression and melatonin secretion

A dyadic perspective on retailer-supplier relationships through the lens of social capital

Social capital theory has received increasing attention as a lens through which to examine supply chain relationships and the value creation process. Despite the growing application of social capital and its three dimensions, namely cognitive, structural and relational capital, to inter-organizational research, few studies in reality have taken a dyadic perspective. Using a paired sample of retailer-supplier relationships from Korean fast-moving consumer goods sector, we explore the configuration of social capital dimensions, and the impact on strategic and operational performance. The results suggest three clusters of relationships, which differ significantly on at least two of the dimensions of social capital. Furthermore, these clusters show considerable differences with respect to both operational and strategic performance, particularly at the lower levels of social capital. We also examine the impact of a disparity between the retailer and supplier with respect to different dimensions of social capital, henceforth called dissonance. Of the four clusters that emerge, interestingly, only dissonance on the cognitive dimension is related to lower operational and strategic relationship performance. In investigating the implications of dissonance for the retailer and supplier individually, our results suggest that performance differs based on the magnitude and direction of the dissonance. Our results show that consequences of having social capital or not are not necessarily the same for the retailer and the supplier

Using machine learning techniques to automate sky survey catalog generation

We describe the application of machine classification techniques to the development of an automated tool for the reduction of a large scientific data set. The 2nd Palomar Observatory Sky Survey provides comprehensive photographic coverage of the northern celestial hemisphere. The photographic plates are being digitized into images containing on the order of 10(exp 7) galaxies and 10(exp 8) stars. Since the size of this data set precludes manual analysis and classification of objects, our approach is to develop a software system which integrates independently developed techniques for image processing and data classification. Image processing routines are applied to identify and measure features of sky objects. Selected features are used to determine the classification of each object. GID3* and O-BTree, two inductive learning techniques, are used to automatically learn classification decision trees from examples. We describe the techniques used, the details of our specific application, and the initial encouraging results which indicate that our approach is well-suited to the problem. The benefits of the approach are increased data reduction throughput, consistency of classification, and the automated derivation of classification rules that will form an objective, examinable basis for classifying sky objects. Furthermore, astronomers will be freed from the tedium of an intensely visual task to pursue more challenging analysis and interpretation problems given automatically cataloged data

Some Properties of the Exchange Operator with respect to Structured Matrices defined by Indefinite Scalar Product Spaces

The properties of the exchange operator on some types of matrices are explored in this paper. In particular, the properties of exc(A,p,q), where A is a given structured matrix of size (p+q)Ã(p+q) and exc : M ÃNÃN â M is the exchange operator are studied. This paper is a generalization of one of the results in [N.J. Higham. J-orthogonal matrices: Properties and generation. SIAM Review, 45:504â519, 2003.]

Governing Embedded Partner Networks: Certification and Partner Communities in the IT Sector

Purpose The complexity of supplier-partner networks in the Information Technology (IT) sector where large suppliers utilize thousands of authorized partners, requires that organizations reconsider their approach to governing and managing the relationships involved. Traditional dyadic approaches to governance are likely to prove inadequate. This paper investigates the relationship between network governance mechanisms and relationship performance. Specifically, we examine the contingent effect of certification of partners and the use of partner communities (as formal and informal mechanisms of network governance, respectively), on complex and embedded networks of relationships. Design/methodology/approach A model examining the effect of formal and informal network governance on the relationship between embeddedness (structural and relational) and relationship performance is developed. Data was collected from a sample of partners of leading IT suppliers in the United Kingdom and Ireland. Three-way interactions assess the contingent effect of certification and partner communities on the relationship between embeddedness and relational performance. Findings Results support the use of a combination of certification and partner communities to strengthen the link between network structure (structural embeddedness) and relational embeddedness, as well as relationship performance. Certification requires the sharing of explicit knowledge with partners whereas partner communities aid the creation and dissemination of more tacit, contextual knowledge. Furthermore, partner communities reinforce positive perceptions of fairness in suppliers’ network management practices, overcoming any perceptions of lock-in or coercive control that certification may suggest. Practical implications Certification, despite all its procedural and reputational benefits, damages partner relationships and needs to be supported by partner communities, which themselves show particularly strong benefits in enhancing network relationships. Originality/value Despite the emerging prevalence of certification and partner communities in business-to-business relationships, to date there is a paucity of research on their effects on partner relationships and performance. Organizations with an extensive network of similar partners may suffer network overload. This research shows that such organizations can manage their partner network more effectively through network governance mechanisms, thereby addressing the challenge of overload

Data-Mining a Large Digital Sky Survey: From the Challenges to the Scientific Results

The analysis and an efficient scientific exploration of the Digital Palomar Observatory Sky Survey (DPOSS) represents a major technical challenge. The input data set consists of 3 Terabytes of pixel information, and contains a few billion sources. We describe some of the specific scientific problems posed by the data, including searches for distant quasars and clusters of galaxies, and the data-mining techniques we are exploring in addressing them. Machine-assisted discovery methods may become essential for the analysis of such multi-Terabyte data sets. New and future approaches involve unsupervised classification and clustering analysis in the Giga-object data space, including various Bayesian techniques. In addition to the searches for known types of objects in this data base, these techniques may also offer the possibility of discovering previously unknown, rare types of astronomical objects.Comment: Invited paper, to appear in Applications of Digital Image Processing XX, ed. A. Tescher, Proc. S.P.I.E. vol. 3164, in press; 10 pages, a self-contained TeX file, and 3 separate postscript figure

Suppression of quantum oscillations and the dependence on site energies in electronic excitation transfer in the Fenna-Matthews-Olson trimer

Energy transfer in the photosynthetic complex of the Green Sulfur Bacteria known as the Fenna-Matthews-Olson (FMO) complex is studied theoretically taking all three subunits (monomers) of the FMO trimer and the recently found eighth bacteriochlorophyll (BChl) molecule into account. We find that in all considered cases there is very little transfer between the monomers. Since it is believed that the eighth BChl is located near the main light harvesting antenna we look at the differences in transfer between the situation when BChl 8 is initially excited and the usually considered case when BChl 1 or 6 is initially excited. We find strong differences in the transfer dynamics, both qualitatively and quantitatively. When the excited state dynamics is initialized at site eight of the FMO complex, we see a slow exponential-like decay of the excitation. This is in contrast to the oscillations and a relatively fast transfer that occurs when only seven sites or initialization at sites 1 and 6 is considered. Additionally we show that differences in the values of the electronic transition energies found in the literature lead to a large difference in the transfer dynamics

Protocol: precision engineering of plant gene loci by homologous recombination cloning in Escherichia coli.

Plant genome sequence data now provide opportunities to conduct molecular genetic studies at the level of the whole gene locus and above. Such studies will be greatly facilitated by adopting and developing further the new generation of genetic engineering tools, based on homologous recombination cloning in Escherichia coli, which are free from the constraints imposed by the availability of suitably positioned restriction sites. Here we describe the basis for homologous recombination cloning in E. coli, the available tools and resources, together with a protocol for long range cloning and manipulation of an Arabidopsis thaliana gene locus, to create constructs co-ordinately driven by locus-specific regulatory elements.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are