Oxidative stress, cellular senescence and ageing

Almost a half century ago, the free radical theory of ageing proposed that the reactive oxygen species (ROS) is a key component which contributes to the pathophysiology of ageing in mammalian cells. Over the years, numerous studies have documented the role of oxidative stress caused by ROS in the ageing process of higher organisms. In particular, several age-associated disease models suggest that ROS and oxidative stress modulate the incidence of age-related pathologies, and that it can strongly influence the ageing process and possibly lifespan. The exact mechanism of ROS and oxidative stress-induced age-related pathologies is not yet very clear. Damage to biological macromolecules caused by ROS is thought to result in many age-related chronic diseases. At the cellular level, increased ROS leads to cellular senescence among other cellular fates including apoptosis, necrosis and autophagy. Cellular senescence is a stable growth arrest phase of cells characterized by the secretion of senescence-associated secretory phenotype (SASP) factors. Recent evidence suggests that cellular senescence via its growth arrest phenotype and SASP factors is a strong contributing factor in the development of age-associated diseases. In addition, we suggest that SASP factors play an important role in the maintenance of age-associated pathologies via a positive feedback mechanism. This review aims to provide an overview of ROS mechanics and its possible role in the ageing process via induction of cellular senescence

Integrated Optics: a Report on the 2nd OSA Topical Meeting

This report surveys the papers presented at the 2nd OSA Topical Meeting on Integrated Optics, which was held 21–24 January 1974 in New Orleans, La

Formality and informality in the summative assessment of motor vehicle apprentices: a case study

This article explores the interaction of formal and informal attributes of competence‐based assessment. Specifically, it presents evidence from a small qualitative case study of summative assessment practices for competence‐based qualifications within apprenticeships in the motor industry in England. The data are analysed through applying an adaptation of a framework for exploring the interplay of formality and informality in learning. This analysis reveals informal mentoring as a significant element which influences not only the process of assessment, but also its outcomes. We offer different possible interpretations of the data and their analysis, and conclude that, whichever interpretation is adopted, there appears to be a need for greater capacity‐building for assessors at a local level. This could acknowledge a more holistic role for assessors; recognise the importance of assessors’ informal practices in the formal retention and achievement of apprentices; and enhance awareness of inequalities that may be reinforced by both informal and formal attributes of assessment practices

Cold atoms in double-well optical lattices

Cold atoms, loaded into an optical lattice with double-well sites, are considered. Pseudospin representation for an effective Hamiltonian is derived. The system in equilibrium displays two phases, ordered and disordered. The second-order phase transition between the phases can be driven either by temperature or by changing the system parameters. Collective pseudospin excitations have a gap disappearing at the phase-transition point. Dynamics of atoms is studied, when they are loaded into the lattice in an initially nonequilibrium state. It is shown that the temporal evolution of atoms, contrary to their equilibrium thermodynamics, cannot be described in the mean-field approximation, since it results in a structurally unstable dynamical system, but a more accurate description is necessary taking account of attenuation effects.Comment: Latex file, 24 pages, 3 figure

the challenge of energy access in africa

There are multiple dimensions to the problem of energy access in Sub-Saharan Africa, where large shares of population lack a reliable supply of electricity and affordable modern cooking fuels: from insufficient power generation capacity, to difficulties in managing energy infrastructure and attract investments in the sector, to challenges in serving low-income users. Booming populations, urbanization, and ambitions of economic development will all demand more energy. This chapter illustrates the main challenges ahead towards the sustainable development objective of achieving universal access to electricity and clean cooking in the region

High frequency statistical arbitrage via the optimal thermal causal path

We consider the problem of identifying similarities and causality relationships in a given set of financial time series data streams. We develop further the “Optimal Thermal Causal Path” method, which is a non-parametric method proposed by Sornette et al. The method considers the mismatch between a given pair of time series in order to identify the expected minimum energy path lead-lag structure between the pair. Traders may find this a useful tool for directional trading, to spot arbitrage opportunities. We add a curvature energy term to the method and we propose an approximation technique to reduce the computational time. We apply the method and approximation technique on various market sectors of NYSE data and extract the highly correlated pairs of time series. We show how traders could exploit arbitrage opportunities by using the method

First evidence for Wollemi Pine-type pollen (Dilwynites: Araucariaceae) in South America

We report the first fossil pollen from South America of the lineage that includes the recently discovered, extremely rare Australian Wollemi Pine, Wollemia nobilis (Araucariaceae). The grains are from the late Paleocene to early middle Eocene Ligorio Márquez Formation of Santa Cruz, Patagonia, Argentina, and are assigned to Dilwynites, the fossil pollen type that closely resembles the pollen of modern Wollemia and some species of its Australasian sister genus, Agathis. Dilwynites was formerly known only from Australia, New Zealand, and East Antarctica. The Patagonian Dilwynites occurs with several taxa of Podocarpaceae and a diverse range of cryptogams and angiosperms, but not Nothofagus. The fossils greatly extend the known geographic range of Dilwynites and provide important new evidence for the Antarctic region as an early Paleogene portal for biotic interchange between Australasia and South America.Mike Macphail, Raymond J. Carpenter, Ari Iglesias, Peter Wil

Equilibrium configurations of two charged masses in General Relativity

An asymptotically flat static solution of Einstein-Maxwell equations which describes the field of two non-extreme Reissner - Nordstr\"om sources in equilibrium is presented. It is expressed in terms of physical parameters of the sources (their masses, charges and separating distance). Very simple analytical forms were found for the solution as well as for the equilibrium condition which guarantees the absence of any struts on the symmetry axis. This condition shows that the equilibrium is not possible for two black holes or for two naked singularities. However, in the case when one of the sources is a black hole and another one is a naked singularity, the equilibrium is possible at some distance separating the sources. It is interesting that for appropriately chosen parameters even a Schwarzschild black hole together with a naked singularity can be "suspended" freely in the superposition of their fields.Comment: 4 pages; accepted for publication in Phys. Rev.

Are self-report of disability pension and long-term sickness absence accurate? Comparisons of self-reported interview data with national register data in a Swedish twin cohort

<p>Abstract</p> <p>Background</p> <p>Self-reported disability pension (DP) and sickness absence are commonly used in epidemiological and other studies as a measure of exposure or even as an outcome. The aims were (1) to compare such self-reports with national register information in order to evaluate the validity of self-reported DP and sickness absence, and (2) to estimate the concordance of reporting behaviour in different twin zygosity groups, also by sex.</p> <p>Methods</p> <p>All Swedish twins born 1933-1958 who participated in the Screening Across the Lifespan Twin study (SALT) 1998-2003, were included (31,122 individuals). The self-reported DP and long-term sickness absence (LTSA) at the time of interview was compared to the corresponding register information retrieved from the National Social Insurance Agency by calculating the proportions of agreements, kappa, sensitivity, specificity, concordance rates, and chi-square test, to evaluate construct validity.</p> <p>Results</p> <p>The proportions of overall agreement were 96% and specificity 99% for both DP and LTSA, while the sensitivity was 70% for DP and 45% for LTSA. Kappa estimates were 0.76 for DP, and 0.58 for LTSA. The proportions of positive agreement were 64% for DP and 42% for LTSA. No difference in response style was found between zygosity groups among complete twin pairs for DP and LTSA. Results were similar for women and men and across age. Kappa estimates for DP differed somewhat depending on years of education, 0.68 (college/university) vs. 0.77 (less than 13 years in school) but not for LTSA.</p> <p>Conclusions</p> <p>Self-reported DP data may be very useful in studies when register information is not available, however, register data is preferred especially for LTSA. The same degree of twin similarity was found for truthful self-report of DP and LTSA in both monozygotic and dizygotic twin pairs. Thus, the response style was not influenced by genetic factors. One consequence of this would be that when estimating the relative importance of genetic and environmental effects from twin models, heritability estimates would not be biased.</p

Online Political Communication Strategies: MEPs, E-Representation, and Self-Representation

Research into the communication strategies of legislators has a long history. The European Parliament offers an opportunity to add to understanding of how legislators prioritize styles of communication, with a comparative perspective across 27 nations. Through content analysis of online communication, we investigate how the Internet is used by members of the European Parliament. Our analysis assesses three communication strategies: homestyle, impression management, and participatory. We find that a homestyle strategy predominates, followed by impression management. Participatory communication is emergent, but may earn legislators political capital, as it appears that proactive communicators who offer participatory opportunities are more likely to build an online following