An Observation about Truth

Tarski's analysis of the concept of truth gives rise to a hierarchy of languages. Does this fragment the concept all the way to philosophical unacceptability? I argue it doesn't, drawing on a modification of Kaplan's theory of indexicals

A Tone reproduction study of a digital image processing system

Photographic tone reproduction analysis was applied to a digital image processing system (DIPS) . The problem was to calculate computer mapping functions for the DIPS that would cause input scenes to be reproduced having Clark\u27s tone reproduction characteristics. Using the graphical method of a Jones Diagram, unique computer mapping functions were constructed for four images processed by the DIPS. After processing the imagery in the computer, the pixels were reconstructed into photographic transparencies for projection in a specially designed projection area. The results of this work concluded that tone reproduction analysis is useful in studying the macro effect of luminance transfer through a DIPS , and that tone reproduction characteristics may be modified digitally using pre-determined computer mapping functions

Fractional cable models for spiny neuronal dendrites

Cable equations with fractional order temporal operators are introduced to model electrotonic properties of spiny neuronal dendrites. These equations are derived from Nernst-Planck equations with fractional order operators to model the anomalous subdiffusion that arises from trapping properties of dendritic spines. The fractional cable models predict that postsynaptic potentials propagating along dendrites with larger spine densities can arrive at the soma faster and be sustained at higher levels over longer times. Calibration and validation of the models should provide new insight into the functional implications of altered neuronal spine densities, a hallmark of normal aging and many neurodegenerative disorders

Treatment of Alport syndrome: beyond animal models

Alport syndrome (AS) is a hereditary glomerulopathy due to abnormal composition of the glomerular basement membrane, leading to end-stage renal disease (ESRD). Studies of animal models of AS have suggested a variety of potentially effective therapies, but none of these has been definitely shown to prevent or delay ESRD in human AS. Studies in Alport mice suggest that angiotensin inhibition not only has antiproteinuric effects but suppresses cytokine and collagen production as well as tubulointerstitial fibrogenesis and inflammation. For these reasons, many Alport patients are treated empirically with angiotensin antagonists. Cyclosporine may reduce proteinuria in AS, but the risk of nephrotoxic side effects complicates long-term therapy in children. Current data on the role of HMG-CoA reductase inhibition are sparse, so therapy should be limited to adults with dyslipoproteinemia. Results of some, but not all, studies suggest that bone marrow–derived cells may ameliorate disease in Alport mice. However, until experimental doubts concerning the superiority of bone-marrow transplantation over other treatments are resolved by additional investigation, human research subjects should not be exposed to cell-based therapies that may carry substantial risks. In summary, all potential therapies are off-label use in children. As a consequence, initial therapeutic trials should focus on the safety and efficiency of medical treatment, as well as the optimal timing of therapy

Environmental variability and modularity of bacterial metabolic networks

<p>Abstract</p> <p>Background</p> <p>Biological systems are often modular: they can be decomposed into nearly-independent structural units that perform specific functions. The evolutionary origin of modularity is a subject of much current interest. Recent theory suggests that modularity can be enhanced when the environment changes over time. However, this theory has not yet been tested using biological data.</p> <p>Results</p> <p>To address this, we studied the relation between environmental variability and modularity in a natural and well-studied system, the metabolic networks of bacteria. We classified 117 bacterial species according to the degree of variability in their natural habitat. We find that metabolic networks of organisms in variable environments are significantly more modular than networks of organisms that evolved under more constant conditions.</p> <p>Conclusion</p> <p>This study supports the view that variability in the natural habitat of an organism promotes modularity in its metabolic network and perhaps in other biological systems.</p

Modular networks emerge from multiconstraint optimization

Modular structure is ubiquitous among complex networks. We note that most such systems are subject to multiple structural and functional constraints, e.g., minimizing the average path length and the total number of links, while maximizing robustness against perturbations in node activity. We show that the optimal networks satisfying these three constraints are characterized by the existence of multiple subnetworks (modules) sparsely connected to each other. In addition, these modules have distinct hubs, resulting in an overall heterogeneous degree distribution.Comment: 5 pages, 4 figures; Published versio

A Blueprint for Collaborative Lawmaking

Miki Kashtan, a consultant at the Center for Efficient Collaboration, describes how her Convergent Facilitation method of collaborative decision-making brought together contentiously divided stakeholders in an effort to redraft child custody legislation in Minnesota, resulting in a near-unanimous new bill that completely changes the approach to child custody. This breakthrough surprised many. It depended on reframing the goals of the legislative effort to find legislation that all could wholeheartedly embrace, based on what mattered to all parties. A commitment to those goals carried the group through two years of an intensive and yet non-adversarial process

Evolving discourse of practices for quality teaching in secondary school mathematics

International audienceThis paper presents initial findings from the project PRAQTAL: PRActices for Quality Teaching. Our project focuses on conceptualizing and identifying teaching practices for quality teaching of secondary school mathematics and physics. This work is driven by the understanding that to document, conceptualize, analyze and promote quality teaching, we need to constitute a discourse which articulates the diverse practices of teachers, in their multiple resolutions, and link them to educational theories on one hand and specific instruments on the other. For this purpose, we adopted Commognition as a conceptual framework. Here, we present our working definition of a teaching practice and our criteria for quality teaching practices. We discuss the procedures for identifying and documenting practices and their representation and illustrate our arguments with an example from the project’s emerging database

Familial hematuria

Hematuria is a common presenting complaint in pediatric nephrology clinics and often has a familial basis. This teaching article provides an overview of causes, diagnosis, and management of the major forms of familial hematuria, Alport syndrome, and thin basement membrane nephropathy