Length-frequency estimation for yellowfin tuna (Thunnus albacares) caught by commercial fishing gear in the Eastern Pacific Ocean

ENGLISH: Methods of collecting samples for the purpose of estimating the numbers and weights of fish caught, by length interval, are described. Several models for two-stage sampling are described, and the equations for the estimators and their variances are given. The results from a brief simulation study are used to show the differences between estimates made with the different models. Estimators for the average weights of fish in the catch and their variances are also described. These average weights are used to provide improved estimates of the total annual catches of yellowfin taken from the eastern Pacific Ocean, east of 150°W, between 1955 and 1990. SPANISH: Se describen los métodos de recoger de muestreo para estimar el número o peso de peces capturados, por intervalo de talla. Se describen varios modelos para el muestreo de dos etapas, y se presentan las ecuaciones para los estimadores y sus varianzas. Se usan los resultados de un breve estudio de simulación para indicar las diferencias entre estimaciones realizadas con los distintosmodelos. También se describe un estimador para el peso promedio de peces en la captura y su varianza. Se usan estos estimadores para calcular estimaciones mejoradas de las capturas anuales totales de aleta amarilla tomadas del Océano Pacífico oriental, al este de 150°W, entre 1955 y 1990. (PDF contains 41 pages.

Stem Anatomy of Climbing Palms in Relation to Long-distance Water Transport

Palms lack secondary growth so their primary vascular system is long-lived and must be minimally vulnerable to dysfunction. For water movement, the axial xylem must be well defended against cavitation. Climbing palms can be very long and represent a maximum solution to transport problems. How is this demonstrated in their anatomy? This article contrasts stem vascular anatomy in a canelike tree palm (Rhapis excelsa) with that in the American climbing palm Desmoncus and the Old World rattan genus Calamus. Rhapis, representing the basic classical palm vasculature, has a continuously integrated vascular system determined by branching of the axial (stem) system to produce leaf traces, bridges, and continuing axial bundles. Axial transport is favored over appendicular structures because leaves are irrigated solely by narrower protoxylem tracheids. Maximum stem vessel length is inherently limited by the leaf contact distance (LCD). Desmoncus is very similar except that interconnections involve more numerous bridges and axial continuity is less obvious. Both Rhapis and Desmoncus retain scalariform perforation plates in their stem vessels. However, Calamus lacks axial continuity because axial bundles extend distally into leaves as leaf traces but end blindly in a basipetal direction. The only interconnection is via narrow transverse commissures (not bridges). Calamus stem metaxylem vessels have simple perforation plates. Resistance to water transport can be calculated, based on axial changes in metaxylem vessel diameter and is very high in the climbing palms. The unique features of Calamus may relate to safety of the hydraulic system as much as its efficiency, with Desmoncus an intermediate condition more clearly based on the classical model of palm vasculature. Calamus may have also evolved to mitigate the limitation of vessel length determined by LCD. Further anatomical solutions to the climbing habit in palms are briefly discussed

The UN local communities and Indigenous peoples' platform: A traditional ecological knowledge-based evaluation

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2019 The Authors. WIREs Climate Change published by Wiley Periodicals, Inc.This review evaluates the potential of the proposed local communities and Indigenous peoples’ platform to effectively engage traditional ecological knowledge (TEK) for climate policy. Specifically, we assess the platform's potential to enable greater representation and participation of Indigenous peoples (IPs) within the United Nations Framework Convention on Climate Change (UNFCCC). An analytical framework based on the extensive TEK and environmental management literature is developed, with a set of criteria identified against which to evaluate the platform. We find that although the process of designing the platform appears to be inclusive of Indigenous views, the structure itself does not recognize the roles that unequal power relations and colonialism play in marginalizing IPs. Limited attention is paid to the institutional barriers within the UNFCCC and the drawbacks of pursuing knowledge “integration” as an end in itself. Based on this, recommendations for improving the platform structure are put forward including using a rights based framing, giving greater decision-making power to IPs, and developing mechanisms to ensure the holistic integrity of TEK and build the overall resilience of climate mitigation and adaptation systems.Ye

The fatigue performance of electrofusion tapping tees subject to contamination

Electrofusion jointing is a common joint process used to weld polyethylene (PE) water pipe in the UK. For many years, the UK Water Industry has experienced a small number of premature failures of electrofusion fittings; this inevitably causes leakage. The common causes of critical failures have been highlighted and as a result of this, a testing programme was designed and implemented to assess the fatigue performance of electrofusion tapping tees if they were to be installed by ‘bad practice’. A fine china talc was used to replicate contamination in the field. The results suggest that failures associated with fatigue are possible in a relatively short space of time on tapping tees when they are subject to contamination. The pressure ranges used in the fatigue regime aimed to replicate the potential magnitude of surge pressures that can be experienced in water distribution mains

Modelling the consequences of interactions between tumour cells.

Classical models of tumorigenesis assume that the mutations which cause tumours to grow act in a cell-autonomous fashion. This is not necessarily true. Sometimes tumour cells may adopt genetic strategies that boost their own replication and which also influence other cells in the tumour, whether directly or as a side-effect. Tumour growth as a whole might be enhanced or retarded. We have used mathematical models to study two non-autonomous strategies that tumour cells may use. First, we have considered the production by tumour cells of an angiogenesis growth factor that benefits both the cell from which it originates and neighbouring cells. Second, we have analysed a situation in which tumour cells produce autocrine-only or paracrine-only growth factors to prevent programmed cell death. In the angiogenesis model, stable genetic polymorphisms are likely to occur between cells producing and not producing the growth factor. In the programmed cell death model, cells with autocrine growth factor production can spread throughout the tumour. Production of paracrine-only growth factor is never selected because it is 'altruistic' (that is of no benefit to the cell that makes the growth factor), despite being potentially beneficial to tumour growth as a whole. No polymorphisms can occur in the programmed cell death model. Production of angiogenesis and other growth factors in tumours may be under stable genetic, rather than epigenetic, control, with implications for therapies aimed at such targets. Many of the mutations observed in tumours may have non-autonomous effects

A novel selective 11b-hydroxysteroid dehydrogenase type 1 inhibitor prevents human adipogenesis.

Glucocorticoid excess increases fat mass, preferentially within omental depots; yet circulating cortisol concentrations are normal in most patients with metabolic syndrome (MS). At a pre-receptor level, 11b-hydroxysteroid dehydrogenase type 1 (11b-HSD1) activates cortisol from cortisone locally within adipose tissue, and inhibition of 11b-HSD1 in liver and adipose tissue has been proposed as a novel therapy to treat MS by reducing hepatic glucose output and adiposity. Using a transformed human subcutaneous preadipocyte cell line (Chub-S7) and human primary preadipocytes, we have defined the role of glucocorticoids and 11b-HSD1 in regulating adipose tissue differentiation. Human cells were differentiated with 1.0 mM cortisol (F), or cortisone (E) with or without 100 nM of a highly selective 11b-HSD1 inhibitor PF-877423. 11b-HSD1 mRNA expression increased across adipocyte differentiation (P!0.001, nZ4), which was paralleled by an increase in 11b-HSD1 oxo-reductase activity (from nil on day 0 to 5.9G1.9 pmol/mg per h on day 16,P!0.01, nZ7). Cortisone enhanced adipocyte differentiation; fatty acid-binding protein 4 expression increased 312-fold (P!0.001) and glycerol-3-phosphate dehydrogenase 47-fold (P!0.001) versus controls. This was abolished by co-incubation with PF-877423. In addition, cellular lipid content decreased significantly. These findings were confirmed in the primary cultures of human subcutaneous preadipocytes. The increase in 11b-HSD1 mRNA expression and activity is essential for the induction of human adipogenesis. Blocking adipogenesis with a novel and specific 11b-HSD1 inhibitor may represent a novel approach to treat obesity in patients with MS

Mathematical modeling of cell population dynamics in the colonic crypt and in colorectal cancer

Colorectal cancer is initiated in colonic crypts. A succession of genetic mutations or epigenetic changes can lead to homeostasis in the crypt being overcome, and subsequent unbounded growth. We consider the dynamics of a single colorectal crypt by using a compartmental approach [Tomlinson IPM, Bodmer WF (1995) Proc Natl Acad Sci USA 92: 11130-11134], which accounts for populations of stem cells, differential cells, and transit cells. That original model made the simplifying assumptions that each cell popuation divides synchronously, but we relax these assumptions by adopting an age-structured approach that models asynchronous cell division, and by using a continuum model. We discuss two mechanims that could regulate the growth of cell numbers and maintain the equilibrium that is normally observed in the crypt. The first will always maintain an equilibrium for all parameter values, whereas the second can allow unbounded proliferation if the net per capita growth rates are large enough. Results show that an increase in cell renewal, which is equivalent to a failure of programmed cell death or of differentiation, can lead to the growth of cancers. The second model can be used to explain the long lag phases in tumor growth, during which news, higher equilibria are reached, before unlimited growth in cell number ensues

Optical Conductivity in a Two-Band Superconductor: Pb

We demonstrate the effect of bandstructure on the superconducting properties of Pb by calculating the strong-coupling features in the optical conductivity, $\sigma(\omega)$, due to the electron-phonon interaction. The importance of momentum dependence in the calculation of the properties of superconductors has previously been raised for MgB$_2$. Pb resembles MgB$_2$ in that it is a two band superconductor in which the bands' contributions to the Fermi surface have very different topologies. We calculate $\sigma(\omega)$ by calculating a memory function which has been recently used to analyze $\sigma(\omega)$ of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. In our calculations the two components of the Fermi surface are described by parameterizations of de Haas--van Alphen data. We use a phonon spectrum which is a fit to neutron scattering data. By including the momentum dependence of the Fermi surface good agreement is found with the experimentally determined strong-coupling features which can be described by a broad peak at around 4.5 meV and a narrower higher peak around 8 meV of equal height. The calculated features are found to be dominated by scattering between states within the third band. By contrast scattering between states in the second band leads to strong-coupling features in which the height of the high energy peak is reduced by $\sim 50$ compared to that of the low energy peak. This result is similar to that in the conventional isotropic (momentum independent) treatment of superconductivity. Our results show that it is important to use realistic models of the bandstructure and phonons, and to avoid using momentum averaged quantities, in calculations in order to get quantitatively accurate results

Machines on Genes: Enzymes that Make, Break and Move DNA and RNA

As the vital information repositories of the cell, the nucleic acids DNA and RNA pose many challenges as enzyme substrates. To produce, maintain and repair DNA and RNA, and to extract the genetic information that they encode, a battery of remarkable enzymes has evolved, which includes translocases, polymerases/replicases, helicases, nucleases, topoisomerases, transposases, recombinases, repair enzymes and ribosomes. An understanding of how these enzymes function is essential if we are to have a clear view of the molecular biology of the cell and aspire to manipulate genomes and gene expression to our advantage. To bring together scientists working in this fast-developing field, the Biochemical Society held a Focused Meeting, ‘Machines on Genes: Enzymes that Make, Break and Move DNA and RNA’, at Robinson College, University of Cambridge, U.K., in August 2009. The present article summarizes the research presented at this meeting and the reviews associated with the talks which are published in this issue of Biochemical Society Transactions