Users manual for the Automated Performance Test System (APTS)

The characteristics of and the user information for the Essex Automated Performance Test System (APTS) computer-based portable performance assessment battery are given. The battery was developed to provide a menu of performance test tapping the widest possible variety of human cognitive and motor functions, implemented on a portable computer system suitable for use in both laboratory and field settings for studying the effects of toxic agents and other stressors. The manual gives guidance in selecting, administering and scoring tests from the battery, and reviews the data and studies underlying the development of the battery. Its main emphasis is on the users of the battery - the scientists, researchers and technicians who wish to examine changes in human performance across time or as a function of changes in the conditions under which test data are obtained. First the how to information needed to make decisions about where and how to use the battery is given, followed by the research background supporting the battery development. Further, the development history of the battery focuses largely on the logical framework within which tests were evaluated

Ontogenetic and temporal variability in the fat content and fatty acid composition of Atlantic herring (Clupea harengus) from the Bay of Fundy, Canada

Atlantic herring (Clupea harengus) is an ecologically and economically valuable species in many food webs, yet surprisingly little is known about the variation in the nutritional quality of these fish. Atlantic herring collected from 2005 through 2008 from the Bay of Fundy, Canada, were examined for variability in their nutritional quality by using total lipid content (n=889) and fatty acid composition (n=551) as proxies for nutritional value. A significant positive relationship was found between fish length and total lipid content. Atlantic herring also had significantly different fatty acid signatures by age. Fish from 2005 had significantly lower total lipid content than fish from 2006 through 2008, and all years had significantly different fatty acid signatures. Summer fish were significantly fatter than winter fish and had significantly different fatty acid signatures. For all comparisons (ontogenetic, annual, and seasonal) percent concentrations of omega-3, -6, and long-chain monounsaturated fatty acids were the most important for distinguishing between the fatty acid signatures of fish. This study underscores the importance of quantifying variation in prey quality synoptically with prey quantity in food webs over ontogenetic and temporal scales when evaluating the effect of prey nutritional quality on predators and on modeling trophic dynamics

Origin of the Eukaryotic Cell

All complex life on Earth is composed of ‘eukaryotic’ cells. Eukaryotes arose just once in 4 billion years, via an endosymbiosis — bacteria entered a simple host cell, evolving into mitochondria, the ‘powerhouses’ of complex cells. Mitochondria lost most of their genes, retaining only those needed for respiration, giving eukaryotes ‘multi-bacterial’ power without the costs of maintaining thousands of complete bacterial genomes. These energy savings supported a substantial expansion in nuclear genome size, and far more protein synthesis from each gene

The unseen world: reflections on Leeuwenhoek (1677) 'Concerning little animals'

Leeuwenhoek's 1677 paper, the famous ‘letter on the protozoa’, gives the first detailed description of protists and bacteria living in a range of environments. The colloquial, diaristic style conceals the workings of a startlingly original experimental mind. Later scientists could not match the resolution and clarity of Leeuwenhoek's microscopes, so his discoveries were doubted or even dismissed over the following centuries, limiting their direct influence on the history of biology; but work in the twentieth century confirmed Leeuwenhoek's discovery of bacterial cells, with a resolution of less than 1 µm. Leeuwenhoek delighted most in the forms, interactions and behaviour of his little ‘animalcules', which inhabited a previously unimagined microcosmos. In these reflections on the scientific reach of Leeuwenhoek's ideas and observations, I equate his questions with the preoccupations of our genomic era: what is the nature of Leeuwenhoek's animalcules, where do they come from, how do they relate to each other? Even with the powerful tools of modern biology, the answers are far from resolved—these questions still challenge our understanding of microbial evolution. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society

Relaxation of quantum states under energy perturbations

The energy-based stochastic extension of the Schrodinger equation is perhaps the simplest mathematically rigourous and physically plausible model for the reduction of the wave function. In this article we apply a new simulation methodology for the stochastic framework to analyse formulae for the dynamics of a particle confined to a square-well potential. We consider the situation when the width of the well is expanded instantaneously. Through this example we are able to illustrate in detail how a quantum system responds to an energy perturbation, and the mechanism, according to the stochastic evolutionary law, by which the system relaxes spontaneously into one of the stable eigenstates of the Hamiltonian. We examine in particular how the expectation value of the Hamiltonian and the probability distribution for the position of the particle change in time. An analytic expression for the typical timescale of relaxation is derived. We also consider the small perturbation limit, and discuss the relation between the stochastic framework and the quantum adiabatic theorem

Why is Life the Way it Is?

The concept of the three domains of life (the bacteria, archaea and eukaryotes) goes back to Carl Woese in 1990. Most scientists now see the eukaryotes (cells with a true nucleus) as a secondary domain, derived from bacteria and archaea via an endosymbiosis. That makes the last universal common ancestor of life (LUCA) the ancestor of bacteria and archaea. While these domains are strikingly different in their genetics and biochemistry, they are nearly indistinguishable in their cellular morphology — historically, both groups have been classed as prokaryotes. In terms of their metabolic versatility and molecular machinery, prokaryotes are if anything more sophisticated than eukaryotes. Yet despite an exhaustive search of genetic sequence space in virtually infinite populations over four billion years, neither domain evolved morphological complexity to compare with eukaryotes5. The evolutionary path to morphological complexity does not seem to depend on genetic information alone. The most plausible explanation is that physical constraints stemming from the topological structure of prokaryotes blocked the evolution of morphological complexity in prokaryotes, and that the endosymbiosis at the origin of eukaryotes relieved these constraints. In this lecture, I shall argue that the dependence of all life on electrical charges across membranes to generate energy explains the structural constraints on prokaryotes, and the escape from these constraints in eukaryotes

Revealed Informal Activity

What does it mean to be in the informal sector? Many characterizations have been used in the literature, for example, firms that are unregistered or employ a small workforce or firms/economic enterprises that do not have access to formal capital markets. But many people participate in both formal and informal activities, while classification of participation is often based on primary employment. This creates limitations to the analytical power of existing measures of informality. We develop a method for assigning households to the informal sector by inferring informal sector activity using income and expenditure surveys. We apply this method to the case of Bulgaria using LSMS income and expenditure surveys before and after a significant economic reform and compare it to those made using other indicators of informal sector activity. Our work shows that the informal sector acts as a buffer for households during periods of crisis when formal sector employment opportunities are limited. It shows the limitations of alternative stylized measures of informality in assessing the vulnerability of households involved in the informal sector, especially during periods of extreme economic hardship.informal labour markets, crisis, Bulgaria

Migration as a Substitute for Informal Activities: Evidence from Tajikistan

How is migration related to informal activities? They may be complementary since new migrants may have difficulty finding employment in formal work, so many of them end up informally employed. Alternatively, migration and informality may be substitutes since migrants' incomes in their new locations and income earned in the home informal economy (without migration) are an imperfect trade-off. Tajikistan possesses both a very large informal sector and extensive international emigration. Using the gap between household expenditure and income as an indicator of informal activity, we find negative significant correlations between informal activities and migration: the gap between expenditure and income falls in the presence of migration. Furthermore, Tajikistan's professional workers ability to engage in informal activities enables them to forgo migration, while low-skilled non-professionals without post-secondary education choose to migrate instead of working in the informal sector. Our empirical evidence suggests migration and informality substitute for one another.remittances, migration, informal, Tajikistan

The Informal Sector During Crisis and Transition

employment, mobility, informal sector, transition, dual economy, Bulgaria