On the Dynamics of the Adenylate Energy System: Homeorhesis vs Homeostasis

Biochemical energy is the fundamental element that maintains both the adequate turnover of the biomolecular structures and the functional metabolic viability of unicellular organisms. The levels of ATP, ADP and AMP reflect roughly the energetic status of the cell, and a precise ratio relating them was proposed by Atkinson as the adenylate energy charge (AEC). Under growth-phase conditions, cells maintain the AEC within narrow physiological values, despite extremely large fluctuations in the adenine nucleotides concentration. Intensive experimental studies have shown that these AEC values are preserved in a wide variety of organisms, both eukaryotes and prokaryotes. Here, to understand some of the functional elements involved in the cellular energy status, we present a computational model conformed by some key essential parts of the adenylate energy system. Specifically, we have considered (I) the main synthesis process of ATP from ADP, (II) the main catalyzed phosphotransfer reaction for interconversion of ATP, ADP and AMP, (III) the enzymatic hydrolysis of ATP yielding ADP, and (IV) the enzymatic hydrolysis of ATP providing AMP. This leads to a dynamic metabolic model (with the form of a delayed differential system) in which the enzymatic rate equations and all the physiological kinetic parameters have been explicitly considered and experimentally tested in vitro. Our central hypothesis is that cells are characterized by changing energy dynamics (homeorhesis). The results show that the AEC presents stable transitions between steady states and periodic oscillations and, in agreement with experimental data these oscillations range within the narrow AEC window. Furthermore, the model shows sustained oscillations in the Gibbs free energy and in the total nucleotide pool. The present study provides a step forward towards the understanding of the fundamental principles and quantitative laws governing the adenylate energy system, which is a fundamental element for unveiling the dynamics of cellular life.

Proceso catalítico de transformación de dimetil éter en olefinas (DTO)

325 p.

Reciclado de polvo inconel 718 y evolución de las propiedades de los componentes fabricados con los mismos.

[ES]El objetivo de este trabajo ha sido la determinación de un proceso para la reutilización del polvo metálico desperdiciado durante el proceso de aporte por láser. El polvo necesita ser inyectado para ser fundido directamente sobre el aporte pero un alto porcentaje de las partículas golpean el área no fundida y directamente rebotan fuera de la zona de aporte. La eficiencia de las partículas depositadas puede bajar hasta el 40 % dependiendo de la configuración y del tamaño del punto de aporte. El material utilizado ha sido la superaleación de níquel Inconel 718 debido a su potencial aplicación en procesos de fabricación aditiva. Después del primer uso, el polvo es recolectado y tamizado. La fracción indeseada es magnéticamente segregada y la parte limpia es nuevamente tamizada para obtener datos y de nuevo mezclada para estar lista para la reutilización. No ha sido añadido polvo nuevo a la fracción recuperada y este procedimiento ha sido repetido 5 veces. Los test experimentales muestran que el material depositado presenta resultados similares a aquellos obtenidos con polvo nuevo. La implementación de este proceso permite la mejora de la eficiencia final reduciendo tanto costes como residuos materiales.

Bilan des recherches sur la crevette rose Penaeus duorarum notialis de Côte d'Ivoire et conséquences en matière d'aménagement

A summary of results obtained from 1969 to 1977 is given. It concerns the biology of the species (ecology and distribution of the adults, behaviour and diel variation of catch rates, reproduction and larval migration, juveniles migration and recruitment at sea, sexual maturity, growth and mortality by marking experiments) and the history of the fishery (catches, efforts, seasonal variations of catch rates). The combined use of a dynamic pool model of Ricker and a production model of Fox leads to the evaluation of the potential of the stock. The simulation of different and combined fishery strategies on adults at sea and juveniles in lagoons, allows the evaluation of the consequences (in yield, value, biomass and potential fecundity) of the different proposed management procedures (reductions in fishing effort, closed seasons on both fisheries).

Fish pass design - criteria for the design and approval of fish passes and other structures to facilitate the passage of migratory fish in rivers

Many of British rivers hold stocks of salmon (Salmo salar L.) and sea trout (Salmo trutta L.) and during most of the year some of the adult fish migrate upstream to the head waters where, with the advent of winter, they will eventually spawn. For a variety of reasons, including the generation of power for milling, improving navigation and measuring water flow, man has put obstacles in the way of migratory fish which have added to those already provided by nature in the shape of rapids and waterfalls. While both salmon and sea trout, particularly the former, are capable of spectacular leaps the movement of fish over man-made and natural obstacles can be helped, or even made possible, by the judicious use of fish passes. These are designed to give the fish an easier route over or round an obstacle by allowing it to overcome the water head difference in a series of stages ('pool and traverse' fish pass) or by reducing the water velocity in a sloping channel (Denil fish pass). Salmon and sea trout make their spawning runs at different flow conditions, salmon preferring much higher water flows than sea trout. Hence the design of fish passes requires an understanding of the swimming ability of fish (speed and endurance) and the effect of water temperature on this ability. Also the unique features of each site must be appreciated to enable the pass to be positioned so that its entrance is readily located. As well as salmon and sea trout, rivers often have stocks of coarse fish and eels. Coarse fish migrations are generally local in character and although some obstructions such as weirs may allow downstream passages only, they do not cause a significant problem. Eels, like salmon and sea trout, travel both up and down river during the course of their life histories. However, the climbing power of elvers is legendary and it is not normally necessary to offer them help, while adult silver eels migrate at times of high water flow when downstream movement is comparatively easy: for these reasons neither coarse fish nor eels are considered further. The provision of fish passes is, in many instances, mandatory under the Salmon and Freshwater Fisheries Act 1975. This report is intended for those involved in the planning, siting, construction and operation of fish passes and is written to clarify the hydraulic problems for the biologist and the biological problems for the engineer. It is also intended to explain the criteria by which the design of an individual pass is assessed for Ministerial Approval.

Guidelines for the scoping and environmental assessment of water resources projects. The environment and water resources projects - Volume 1

The following brief is to ensure standard criteria and format are used for the scoping and environmental assessment of water resources projects leading to the production of an environmental report or Environmental Statement. This volume is one of a series giving guidance on water resources projects. The water resources projects will predominantly comprise drought orders and permits, time limited and permanent licences. Smaller projects, such as spray irrigation licences, will not require an environmental assessment. This document forms the basis for discussions between the Environment Agency North East Region, consultees and the applicant. The process aims to produce a thorough assessment. Each section addresses consecutive elements of the assessment process. Section 2 outlines the structure for a scoping document, section 3 outlines the structure for an Environmental Statement and section 4 gives guidance on the role of an Environmental Action Plan. Appendices 1 and 2 should be used in conjunction with the scoping process and cover a wide range of aspects. However, some projects may not require all of them to be included, whilst for others, the inclusion of additional factors may be appropriate.

Distribution patterns of tidepool fishes on a tropical flat reef

Rockpools on a tropical f lat reef off the southeastern coast of Brazil were sampled to determine the influence of pool morphometry and water characteristics on fish community structure. The pool closest to the inner fringe of the reef had lower salinity and higher temperature due to inflow of groundwater. The other pools varied only with respect to their morphometric characteristics, algal cover, and bottom composition. Species with a strong affinity for estuarine- like waters characterized the pool closest to the beach and distinguished its fish community from that of the other pools. Instead of being strongly structured by the physicochemical setting and position in the reef, fish communities of the other pools were determined by behavioral preferences and intra- and interspecific interactions. Differences in community structure were related to pool size (the larger sizes permitting the permanency of schooling species), to algal cover (which allowed camouflage for large predatory species), to bottom composition (which provided substrate for turf flora available to territorial herbivores), and to ecological effects (e.g., competition, territoriality, and predation). Although distribution patterns of tidepool fishes have previously been related to the availability of niches, independent of pool position in the reef, our results show synergistic interactions between water properties, presence or absence of niches, and ecological relationships in structuring tidepool fish communities.

Fatores preditores de abandono de tratamento de tuberculose: uma metanálise

A tuberculose (TB) é uma doença que foi declarada pela Organização Mundial de Saúde como emergência mundial em 1993. As ferramentas disponíveis hoje para controle da TB são: o diagnóstico precoce e o tratamento eficiente. Porém, o abandono do tratamento de TB é um problema enfrentado mundialmente em proporções que podem variar entre 3% a 80%. Por isso, a identificação dos fatores que são preditores do abandono do tratamento de TB pode ajudar a desenvolver melhores estratégias para o seu controle. O objetivo deste trabalho é, através de uma metanálise, fazer uma estimativa sumária da medida de associação entre cada um dos fatores (a) relacionados ao serviço de saúde, (b) relacionado ao quadro clínico e à terapia da TB e (c) relacionados aos indivíduos e o abandono do tratamento de TB. A estratégia de busca eletrônica remota para a recuperação de publicações relevantes foi desenvolvida de forma específica para as diferentes bases consideradas relevantes (MEDLINE [Pubmed] e LILCS). Buscas por referências cruzadas, além da consulta à base de revisões sistemáticas COCHRANE, também foram realizadas. Investigações foram incluídas se fossem trabalhos observacionais ou experimentais que estudem fatores de risco ou preditores do desfecho de interesse (abandono do tratamento de tuberculose) através de comparações de dois ou mais grupos e se seus dados pudessem ser extraídos. Dois revisores classificaram os trabalhos e extraíram dados de forma mascarada e as discordâncias resolvidas. Mais de 190 textos completos foram aptos à combinação de dados. Destes, foi possível extrair dados para combinação de 40 exposições. Destas, 19 foram demonstradas nesta investigação. Das 19 demonstradas, 13 exposições estudadas apresentaram associação e poderiam ser considerados preditores (sexo masculino, alcoolismo, infecção pelo HIV/SIDA, uso de drogas ilícitas, nacionalidade estrangeira, analfabetismo, retratamento, baciloscopia positiva, abandono prévio, tratamento de curta duração, acesso fácil à unidade de saúde, treinamento para adesão, tuberculose extrapulmonar) e seis não apresentaram associação (desemprego, efeitos adversos, tuberculose resistente, necessidade de hospitalização, demora para o início do tratamento, espera longa para a consulta). Porém, essas associações devem ser consideradas de forma conservadora devido à elevada heterogeneidade encontrada em todas as exposições. Apenas cinco exposições apresentaram explicação parcial e uma apresentou explicação total para a heterogeneidade. O viés de publicação foi detectado em apenas duas das 19 exposições.

Sources of variability in the free-ball micro-scale abrasion test

In the 'free-ball' version of the micro-scale abrasion or ball-cratering test the rotating ball rests against a tilted sample and a grooved drive shaft. Tests under nominally identical conditions with different apparatus commonly show small but significant differences in measured wear rate. An indirect method has been developed and demonstrated for continuous on-line measurement of the coefficient of friction in the free-ball test. Experimental investigation of the effects of sample tilt angle and drive shaft groove width shows that both these factors influence the stability of the rotation of the ball, and the shape of the abrasive slurry pool, which in turn affect the coefficient of friction in the wear scar area and the measured wear rate. It is suggested that in order to improve the reproducibility of this method the geometry of the apparatus should be specified. For the apparatus used in this work with a steel ball of 25 mm diameter, a sample tilt angle of 60-75° and a shaft groove width of about 10mm provided the most stable ball motion and a wear rate which showed least variability. © 2004 Elsevier B.V. All rights reserved.

A riqueza e diversidade de anfíbios anuros da Serra do Mendanha, Estado do Rio de Janeiro, RJ: grau de conservação da floresta, variação altitudinal e uso de recursos hídricos

Os anfíbios anuros que habitam o bioma Mata Atlântica, especialmente em sua floresta ombrófila densa, são pouco conhecidos sob diversos aspectos de sua ecologia, existindo poucas informações disponíveis na literatura científica. Estes dados estão limitados a poucas localidades, geralmente estudos realizados em fragmentos remanescentes do sudeste brasileiro. A mata bem conservada que recobre os 3300 ha da Serra do Mendanha, apesar de localizada na região metropolitana do Estado do Rio de Janeiro, ainda não tinha sua anurofauna conhecida. No presente estudo, recolhemos informações ecológicas sobre as espécies que habitam a região, especialmente da assembléia encontrada no folhiço que recobre o solo, com o uso de diferentes metodologias: armadilhas de queda; parcelas cercadas; procura visual e auditiva em transecções e encontros ocasionais; assim como dados abióticos do ambiente regional (profundidade do folhiço; níveis de pH; taxa de oxigênio dissolvido; temperaturas do ar e da água; umidade do ar). Exemplares-testemunho foram fixados e depositados na coleção de anfíbios do Museu Nacional, Rio de Janeiro. A anurofauna da Serra do Mendanha é composta por pelo menos 44 espécies que estão distribuídas em 12 famílias, sendo a família Hylidae com o maior número de espécies (50%, n = 22), enquanto que Physalaemus signifer foi a espécie mais abundante (18%, n = 272), sendo habitante do folhiço. A espécie Rhinella ornata contribuiu com a maior biomassa (m = 548 g). Identificamos uma nova espécie de anuro (Brachycephalidae), que também habita o folhiço das cotas altimétricas acima de 700 m. Biogeograficamente a comunidade de anuros da área estudada indicou ser mais similar (68%) com a comunidade da região da Serra da Tiririca e arredores. Comparando-se os três tipo de fisionomias, ou mesohábitats, existentes na Serra do Mendanha, em termos de riqueza e diversidade, a floresta secundária indicou ter os mais elevados índices, seguido pela floresta pouco perturbada e pela monocultura de bananeiras. A assembléia de anuros que habita o folhiço da Serra do Mendanha é composta por nove espécies, que pouco diferiu ao longo de um gradiente altitudinal (0 a 900 m), com o registro das espécies Euparkerella brasiliensis, H. binotatus, Leptodactylus marmoratus e Zachaenus parvulus na maioria das cotas altimétricas. A altitude, a declividade e profundidade do folhiço foram as variáveis abióticas que mais influenciaram na distribuição de abundância e de riqueza de espécies do folhiço. Na estação úmida (setembro a março) a densidade de anuros no folhiço foi de 10,4 ind./100m2, enquanto que na estação seca (abril a agosto) houve uma redução de 34,6% (6,8 ind./100m2). As assembléias de anuros utilizam os recursos hídricos disponíveis na Serra do Mendanha (água da chuva, córregos, fitotelmas, rios e umidade do ar), de diferentes formas, associadas diretamente ao modo reprodutivo de cada espécie. A altitude, a temperatura da água e o pH afetaram a distribuição de espécies de girinos nos diferentes sítios reprodutivos. O modo reprodutivo 1 foi o mais freqüente (n = 18) entre os 14 modos identificados. O estudo de 12 poças (lênticas e lóticas) indicou que estas diferiram consistentemente entre si, seja nas suas dimensões, na composição de suas assembléias de girinos e nos seus componentes abióticos. Diversos predadores de girinos foram encontrados em algumas poças. A assembléia de girinos de cada poça indicou ser moldada pela interação de diferentes fatores ambientais, ecológicos e filogenéticos de cada espécie

Research in Global Groundfish Markets: An Exercise in International Cooperation

Over roughly the last decade, most of the fishery resources of the continental shelf and nearshore areas of the world's oceans have come under the control of coastal nations. One consequence of this extension of fisheries jurisdiction (EFJ) by any individual state has been the expansion of its production possibilities. That is, with strengthened property rights in the ocean resources off its shores, a coastal nation experiences increased opportunities to produce goods and services from its newly enlarged pool of resources. Such a nation, then, would appear to be a potential gainer from EFJ.

South Area still waters 1995 November surveys

This is the South Area still waters 1995 November surveys from the National Rivers Authority, 1996. The report focuses on the surveys of ten Cheshire Meres (Betley, Budworth, Combermere, Hatchmere, Oak mere, Pick mere, Redes, Rostherne, Tabley, and Tatton) previously surveyed in November 1994 and May 1995. Eight others (Chapel Mere, Little Mere, Marbury Mere, Mere Mere, Oss Mere, Petty Pool, Quoisley Big Mere and Tabley Moat) were surveyed for the first time. Two other lakes, Carr Mill Dam and Pennington Flash, were surveyed. Neither of these are considered to be part of the Cheshire meres group of lakes but are of a Regional interest. This report discusses the results of the November 1995 survey before making a comparison between these and the November 1994 survey results. The section on results contains information about water column profile; nutrients (chlorophyll a; Phaeophytin; Nitrate and Nitrite; Ammonia; ortho-Phosphate; Silicate; and total Phosphorus.

Cheshire stillwaters. Summary results of September 1998

This is the Cheshire stillwaters. Summary results of September 1998 from the Environment Agency, 1998. In May 1997, a Stillwaters meeting was held to discuss the way forward in stillwaters monitoring. It decided upon the establishment of a three year rolling programme, in which three stillwaters would be monitored three times a year, every third year. Oak Mere, Tatton Park Mere and Hatch Mere were surveyed between the 29th - 30th September as part of the three year rolling programme. Betley Mere, Petty Pool, Scotman's Flash and Pearson's Flash were also surveyed. Surveys also included algal and zooplankton samples, which are to be analysed by APEM and presented in the end of year report. The section on results contains information about water column profile; and nutrients (chlorophyll a; Phaeophytin; Nitrate and Nitrite; Ammonia; ortho-Phosphate; Silicate; and total Phosphorus).

Cheshire stillwaters summary results 1999

This is the Cheshire stillwaters summary results 1999 from the Environment Agency North West. In May 1997, a Stillwaters meeting was held to discuss the way forward in stillwaters monitoring. It decided upon the establishment of a three year rolling programme, in which three stillwaters would be monitored three times a year, every third year. During 1999, stillwaters monitored for the third year of the Stillwaters Monitoring Programme were Tabley Mere, Comber Mere and Norbury Mere. Surveys of Petty Pool and Betley Mere continued for a second and third year respectively after water quality concerns were highlighted in previous end-of-year reports. Oak Mere was also surveyed for the third year running due to its unusual ecology. This year, the variety of parameters monitored was limited to algal, zooplankton and water chemical samples. Fisheries and marginal invertebrate surveys were not completed due to lack of resources.

Cheshire stillwaters summary results 1999 of different Meres

This is the Cheshire Stillwaters Summary results of 1999 produced by the Environment Agency on February 2000. The report highlights the water quality concerns of those areas surveyed by the Stillwaters Monitoring Programme: Oak Mere, Betley Mere, Petty Pool, Tabley Mere, Comber Mere and Norbury Mere. The report contains divided by area sections on physic-chemical characteristics and water chemistry, Algal and Zooplankton surveys, Discussion, Planned Surveys 2000 and survey maps. 1999 data from Petty Pool, Betley Mere, Comber Mere and Tabley Mere were classified by the trophic status of each stillwater as hyper-eutrophic/ eutrophic, and Oak Mere were classified as mesotrophic/ eutrophic.