Universal Portfolios With and Without Transaction Costs

A constant rebalanced portfolio is an investment strategy which keeps the same distribution of wealth among a set of stocks from period to period. Recently there has been work on on-line investment strategies that are competitive with the best constant rebalanced portfolio determined in hindsight (Cover, 1991, 1996; Helmbold et al., 1996; Cover & Ordentlich, 1996a, 1996b; Ordentlich & Cover, 1996). For the universal algorithm of Cover (Cover, 1991),we provide a simple analysis which naturallyextends to the case of a fixed percentage transaction cost (commission ), answering a question raised in (Cover, 1991; Helmbold et al., 1996; Cover & Ordentlich, 1996a, 1996b; Ordentlich & Cover, 1996; Cover, 1996). In addition, we present a simple randomized implementation that is significantly faster in practice. We conclude by explaining how these algorithms can be applied to other problems, such as combining the predictions of statistical language models, where the resulting guarantees are more striking.     

Representing the task in Bayesian reasoning: Comment on Lovett and Schunn (1999).

The RCCL model (M. C. Lovett and C. D. Schunn, 1999; see record 1999-05245-001) produces predictions that are non-novel or that do not truly spring from its principles. However, it offers the valuable insight that learning processes may affect the selection of both representations and strategies within those representations, and points the way to possible theoretical progress on implicit and explicit control. The authors' account of base-rate neglect under direct experience is compared with RCCL, and it is concluded that learning-based models allow for tests that are not fostered by representation-based models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved and more environmentally friendly charcoal production system using a low-cost retort–kiln (Eco-charcoal)

Research into a low-cost retort–kiln, used to produce charcoal from sustainably managed forests in a more environmentally friendly way (Eco-Charcoal), has been completed and pilot units have been built in India and East Africa. The unit is called ICPS (Improved Charcoal Production System). Importantly, it has a much higher efficiency rating than traditional earth-mound kilns, which have until now been the main means of domestic charcoal production in developing nations. The efficiency of traditional charcoal production methods is about 10%–22% (calculated on using oven-dry wood with 0% water content) while the efficiency of the ICPS is approximately 30%–42%. As compared with traditional carbonisation processes, the ICPS reduces emissions to the atmosphere by up to 75%. The ICPS works in two different phases. During the first phase the ICPS works like a traditional kiln; however, waste wood is burned in a separate fire box to dry the wood. During the second phase of operation the harmful volatiles are burned in a hot ‘fire chamber’ meaning all resulting emissions are cleaner, minus these already reduced volatiles. The heat gained by flaring the wood gazes, is used and recycled to accelerate the carbonisation process. Unlike traditional methods the ICPS can complete a carbonisation cycle within 12 h.     

Internet Authorship: Social and Political Implications Within Kyrgyzstan

This paper presents the results of our corroborated study of grassroots Internet sites and authors in the nation of Kyrgyzstan, exceptional in Central Asia for its deregulated Internet policy. The study presents a set of semistructured interviews with notable grassroots Internet authors and activists, including bloggers, forum participants, and journalists, and analyzes this data via a critical communication and media studies lens to point to significant implications on emergent social, cultural, and political movements in the nation.     

Factors influencing racial comparisons of self-esteem: A quantitative review.

Research on racial comparisons of self-esteem was examined. Early research in this area, exemplified by the doll studies of racial preference, was viewed as demonstrating that Blacks have less self-regard than Whites. However, a meta-analytic synthesis of 261 comparisons, based largely on self-esteem scales and involving more than half a million respondents, revealed higher scores for Black than for White children, adolescents, and young adults. This analysis further revealed that the direction and magnitude of racial differences are influenced by such demographic characteristics as participant age and socioeconomic status, as well as by characteristics of the measuring instruments. Many findings—for example, that the self-esteem advantage for Black respondents increases with age and is related to the sex composition of the sample—underscore the need for long-term longitudinal studies of self-esteem development in male and female members of both racial groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heroes or Sibyls? Gender and engineering ethics

Interest in gender as an analytical category in the study of engineering has grown rapidly through continuing concerns about the low numbers of women in the profession. What would a gender-informed engineering ethics look like? In exploring this question, my aim is to think about how these concerns translate into engineering ethics and thereby to demonstrate that certain constructs may not serve men and women equally well. Hence, exploring such tensions and making novel connections between engineering ethics and feminist ethics can offer the beginnings of a gender-aware and ultimately more inclusive ethics for engineering. To achieve this, I examine one aspect of contemporary thinking in engineering ethics in terms of the “moral hero”. The moral hero tends to be not only strongly masculine but also very individualistic. However, as recent writings on feminist ethics argue against hegemonic masculinity and the inherent individualism it often entails, I offer two alternatives. The first is a consideration of the possibilities inherent in care ethics for a more collective and less overtly masculine theme for engineering and technology ethics. The second is a classical concept, in terms of the “Sibyl”, the ancient prophetess or oracle, which may be particularly useful in understanding the historical exclusion of women from technical disciplines, and which also may inspire alternative moral decision heuristics, although she is not a symbol that emphasizes collectivity in ethics     

Easy to use and rapid isolation and detection of a viral nucleic acid by using paramagnetic microparticles and carbon nanotubes-based screen-printed electrodes

A method that is easy to use, rapid, with a low cost of detecting viral nucleic acid in a biological sample represents the essential tool in targeted therapy. In this study, we report the use of paramagnetic microparticles covered by streptavidin and modified by an oligonucleotide probe with a specific viral sequence labeled by biotin to detect human immunodeficiency virus (HIV) and influenza virus subtype H5N1. The viral nucleic acids were primarily detected by adsorptive transfer stripping technique coupled with square wave voltammetry using carbon paste, hanging mercury drop or carbon nanotubes-based screen-printed working electrodes. Detection limits were estimated for both sequences down to picograms per 3 μl. To isolate the viral sequences, paramagnetic microparticles covered with biotin-labeled oligonucleotides were used. We calculated the yield of isolation for H5N1 and/or HIV sequences, which was defined as “isolated concentration of viral nucleic acid sequence”/“given viral nucleic acid sequence” × 100. We estimated the yield for both sequences as 59%. Moreover, we studied the influence of human serum, dsDNA and non-complementary sequence of nucleic acids on isolation of viral nucleic acids. We also used carbon nanotubes-based screen-printed electrodes coupled with micro-flow instrument to detect viral nucleic acids. We were able to isolate and detect nanogram amounts of nucleic acids.     

Updated Correlation Between Aircraft Smoke Number and Black Carbon Concentration

Aircraft emissions of black carbon (BC) contribute to anthropogenic climate forcing and degrade air quality. The smoke number (SN) is the current regulatory measure of aircraft particulate matter emissions and quantifies exhaust plume visibility. Several correlations between SN and the exhaust mass concentration of BC (C _BC) have been developed, based on measurements relevant to older aircraft engines. These form the basis of the current standard method used to estimate aircraft BC emissions (First Order Approximation version 3 [FOA3]) for the purposes of environmental impact analyses. In this study, BC with a geometric mean diameter (GMD) of 20, 30, and 60 nm and filter diameters of 19 and 35 mm are used to investigate the effect of particle size and sampling variability on SN measurements. For BC with 20 and 30 nm GMD, corresponding to BC emitted by modern aircraft engines, a smaller SN results from a given C _BC than is the case for BC with 60 nm GMD, which is more typical of older engines. An updated correlation between C _BC and SN that accounts for typical size of BC emitted by modern aircraft is proposed. An uncertainty of ±25% accounts for variation in GMD in the range 20–30 nm and for the range of filter diameters. The SN–C _BC correlation currently used in FOA3 underestimates by a factor of 2.5–3 for SN ≤15, implying that current estimates of aircraft BC emissions derived from SN are underestimated by the same factor.

Copyright 2013 American Association for Aerosol Research