Group descent algorithms for nonconvex penalized linear and logistic regression models with grouped predictors

Penalized regression is an attractive framework for variable selection problems. Often, variables possess a grouping structure, and the relevant selection problem is that of selecting groups, not individual variables. The group lasso has been proposed as a way of extending the ideas of the lasso to the problem of group selection. Nonconvex penalties such as SCAD and MCP have been proposed and shown to have several advantages over the lasso; these penalties may also be extended to the group selection problem, giving rise to group SCAD and group MCP methods. Here, we describe algorithms for fitting these models stably and efficiently. In addition, we present simulation results and real data examples comparing and contrasting the statistical properties of these methods

Design of a single chamber air cathode microbial fuel cell using a stainless steel spiral anode and 3D printing techniques for continuous flow dye decolourisation

Microbial fuel cells (MFC) offer a novel solution in wastewater treatment systems. Their capacity for COD removal and concomitant electricity generation are highly attractive properties for reducing costs & environmental impacts in industry. MFCs require expensive membranes & catalysts such as Nafion and platinum respectively to achieve increased power output, but the cost of these materials is prohibitive for real world applications. An air breathing, 1 litre-scale spiral anode MFC was designed (Fig. 1) to provide a high electrode surface area to reactor volume ratio using commonly and cheaply available materials such as stainless steel and activated carbon. Non-platinum group metal catalysts (FeAAPyr family) were integrated into a PVDF cathode fabricated using single step phase inversion to improve rate of the oxygen reduction reaction. Anode surface area was maximized by concertina folding and spiral arrangement and its surface was modified using sulphuric acid, heat treatment & carbon black adsorption to provide a more biocompatible surface for biofilms. The performance characteristics of the designed MFC are currently being investigated. Decolourisation of Acid orange-7 azo dye & COD removal were initially investigated in recirculating batch mode followed by continuous flow configuration with a hydraulic retention time of 36 hours. Optimisation of hydraulic retention times, cathode construction & anode surface modification will present a feasible system for the scale up of microbial fuel cells for industrial use, maximizing COD removal & electricity production

Degradation of azo dyes (Acid orange 7) in a microbial fuel cell: comparison between anodic microbial-mediated reduction and cathodic laccase-mediated oxidation

Microbial fuel cells (MFCs) are a promising technology for the simultaneous treatment of wastewater and electricity production. With regard to azo-dye containing wastewater (e.g. from textile manufacturing), the dyes may be fed via the anode chamber containing electrochemically active bacteria or via the cathode chamber containing laccase enzyme as catalyst for oxygen reduction. This study investigated which of the two approaches is the best with regard to rate of decolourisation of the dye (Acid orange 7), COD reduction and electricity production. The power density was higher for the MFCdye at cathode (25 mW/m2, COD reduction 80%) compared with 18 mW/m2 (COD reduction 69%) for MFCdye at anode (Shewanella oneidensis as catalyst). The decolourisation rate of the dye was not statistically significant between the two approaches with ca. 75% decolourisation achieved in 24 h. The anodic dye degradation products were unstable when exposed to air resulting in what seems to be induced diazotization and regaining of colour. In case of degradation by laccase in the cathode chamber, the decolourisation products were stable and simpler in chemical structure (e.g. presence of aliphatic compounds) as determined by GC-MS. This work suggests that feeding azo dyes in cathode chambers of MFCs containing laccase is a better way of treating the dyes than the commonly used approach of feeding the dye in the anode chamber

Thinking about Later Life: Insights from the Capability Approach

A major criticism of mainstream gerontological frameworks is the inability of such frameworks to appreciate and incorporate issues of diversity and difference in engaging with experiences of aging. Given the prevailing socially structured nature of inequalities, such differences matter greatly in shaping experiences, as well as social constructions, of aging. I argue that Amartya Sen’s capability approach (2009) potentially offers gerontological scholars a broad conceptual framework that places at its core consideration of human beings (their values) and centrality of human diversity. As well as identifying these key features of the capability approach, I discuss and demonstrate their relevance to thinking about old age and aging. I maintain that in the context of complex and emerging identities in later life that shape and are shaped by shifting people-place and people-people relationships, Sen’s capability approach offers significant possibilities for gerontological research