Efeito da proporcao NH4+/NO3- na distribuicao de nitrato e na atividade in vitro da redutase do nitrato de plantas de Panicum maximum.

O objetivo deste trabalho foi estudar os efeitos da nutricao nitrica e amoniacal na distribuicao de nitrato e na atividade in vitro da redutase do nitrato em plantas de capim coloniao ( Panicum maximum Jacq.). as plantas receberam 7 mM de nitrogenio nas forma N- NH4 +, N-NO3- ou combinadas nas seguintes proporcoes 0/100, 25/75, 50/50, 75/25 e 100/0. A extracao enzigmatica foi feita em Tris-HCI 50mM pH 7,5, EDTA 0,5 mM e b-mercaptoetanol 10mM, e para o ensaio utilizou-se 200 mmoles de Tris-HCI pH 7,5, 20 mmoles KNO3, 0,1 mmol NADH e 0,1 mL de Triton X-100 1% no volume final de 2,0 mL. A concentracao de nitrato foi levemente superior na parte aerea quando as plantas receberam ambas as formas de nitrogenio, e na raiz seta decresceu com o aumento da proporcao de aminio. A atividade in vitro de redutase do nitrato so foi observada nas folhas e foi maior quando as plantas receberam ambas as formas de nitrogenio. Os resultados sugerem um efeito estimulador do amonio no tranporte de nitrato e na atividade de redutase do nitrato quando NO3- esta presente.

International transport costs and the margins of Intra-Latin American maritime trade.

This paper focuses on the analysis of the relationship between maritime trade and transport cost in Latin America. The analysis is based on disaggregated (SITC 5 digit level) trade data for intra Latin maritime trade routes over the period 1999-2004. The research contributes to the literature by disentangling the effects of transport costs on the range of traded goods (extensive margin) and the traded volumes of goods (intensive margin) of international trade in order to test some of the predictions of the trade theories that introduce firm heterogeneity in productivity, as well as fixed costs of exporting. Recent investigations show that spatial frictions (distance) reduce trade mainly by trimming the number of shipments and that most firms ship only to geographically proximate customers, instead of shipping to many destinations in quantities that decrease in distance. Our analyses confirm these findings and show that the opposite pattern is observed for ad-valorem freight rates that reduce aggregate trade values mainly by reducing the volume of imported goods (intensive margin).

In Common Cause: The NATO Multilateral Force and Mixed-Manning Demonstration on USS Claude V. Ricketts, 1964-1965

Priest, A. (2005). In Common Cause: The NATO Multilateral Force and Mixed-Manning Demonstration on USS Claude V. Ricketts, 1964-1965. Journal of Military History, 69 (3), 759-789. RAE2008

EXPERIMENTAL INVESTIGATION OF LINEAR BUBBLE DYNAMICS IN A VISCOELASTIC XANTHAN GEL

Oceanic bubble plumes caused by ship wakes or breaking waves disrupt sonar communi- cation because of the dramatic change in sound speed and attenuation in the bubbly fluid. Experiments in bubbly fluids have suffered from the inability to quantitatively characterize the fluid because of continuous air bubble motion. Conversely, single bubble experiments, where the bubble is trapped by a pressure field or stabilizing object, are limited in usable frequency range, apparatus complexity, or the invasive nature of the stabilizing object (wire, plate, etc.). Suspension of a bubble in a viscoelastic Xanthan gel allows acoustically forced oscilla- tions with negligible translation over a broad frequency band. Assuming only linear, radial motion, laser scattering from a bubble oscillating below, through, and above its resonance is measured. As the bubble dissolves in the gel, different bubble sizes are measured in the range 240 – 470 μm radius, corresponding to the frequency range 6 – 14 kHz. Equalization of the cell response in the raw data isolates the frequency response of the bubble. Compari- son to theory for a bubble in water shows good agreement between the predicted resonance frequency and damping, such that the bubble behaves as if it were oscillating in water.

Resonant and Secular Orbital Interations

In stable solar systems, planets remain in nearly elliptical orbits around their stars. Over longer timescales, however, their orbital shapes and sizes change due to mutual gravitational perturbations. Orbits of satellites around a planet vary for the same reason. Because of their interactions, the orbits of planets and satellites today are different from what they were earlier. In order to determine their original orbits, which are critical constraints on formation theories, it is crucial to understand how orbits evolve over the age of the Solar System. Depending on their timescale, we classify orbital interactions as either short-term (orbital resonances) or long-term (secular evolution). My work involves examples of both interaction types. Resonant history of the small Neptunian satellites In satellite systems, tidal migration brings satellite orbits in and out of resonances. During a resonance passage, satellite orbits change dramatically in a very short period of time. We investigate the resonant history of the six small Neptunian moons. In this unique system, the exotic orbit of the large captured Triton (with a circular, retrograde, and highly tilted orbit) influences the resonances among the small satellites very strongly. We derive an analytical framework which can be applied to Neptune's satellites and to similar systems. Our numerical simulations explain the current orbital tilts of the small satellites as well as constrain key physical parameters of both Neptune and its moons. Secular orbital interactions during eccentricity damping Long-term periodic changes of orbital shape and orientation occur when two or more planets orbit the same star. The variations of orbital elements are superpositions of the same number of fundamental modes as the number of planets in the system. We investigate how this effect interacts with other perturbations imposed by external disturbances, such as the tides and relativistic effects. Through analytical studies of a system consisting of two planets, we find that an external perturbation exerted on one planet affects the other indirectly. We formulate a general theory for how both orbits evolve in response to an arbitrary externally-imposed slow change in eccentricity.

Safer by design: using computer simulation to predict the evacuation performance of passenger ships

When designing a new passenger ship or modifiying an existing design, how do we ensure that the proposed design is safe from an evacuation point of view? In the building and aviation industries, computer based evacuation models are being used to tackle similar issues. In these industries, the traditonal restrictive prescriptive approach to design is making way for performance based design methodologies using risk assessment and computer simulation. In the maritime industry, ship evacuation models off the promise to quickly and efficiently bring these considerations into the design phase, while the ship is "on the drawing board". This paper describes the development of evacuation models with applications to passenger ships and further discusses issues concerning data requirements and validation.

The development of a CFD based simulator for water mist suppression systems: the development of the fire submodel

The FIRE Detection and Suppression Simulation (FIREDASS) project was concerned with the development of water misting systems as a possible replacement for halon based fire suppression systems currently used in aircraft cargo holds and ship engine rooms. As part of this program of work, a computational model was developed to assist engineers optimize the design of water mist suppression systems. The model is based on Computational Fluid Dynamics (CFD) and comprised of the following components: fire model; mist model; two-phase radiation model; suppression model; detector/activation model. In this paper the FIREDASS software package is described and the theory behind the fire and radiation sub-models is detailed. The fire model uses prescribed release rates for heat and gaseous combustion products to represent the fire load. Typical release rates have been determined through experimentation. The radiation model is a six-flux model coupled to the gas (and mist) phase. As part of the FIREDASS project, a detailed series of fire experiments were conducted in order to validate the fire model. Model predictions are compared with data from these experiments and good agreement is found.

Safer by design: simulating fire and escape at sea

When designing a new passenger ship or modifying an existing design, how do we ensure that the proposed design and crew emergency procedures are safe from an evacuation resulting from fire or other incident? In the wake of major maritime disasters such as the Scandinavian Star, Herald of Free Enterprise, Estonia and in light of the growth in the numbers of high density, high-speed ferries and large capacity cruise ships, issues concerning the evacuation of passengers and crew at sea are receiving renewed interest. Fire and evacuation models with features such as the ability to realistically simulate the spread of fire and fire suppression systems and the human response to fire as well as the capability to model human performance in heeled orientations linked to a virtual reality environment that produces realistic visualisations of the modelled scenarios are now available and can be used to aid the engineer in assessing ship design and procedures. This paper describes the maritimeEXODUS ship evacuation and the SMARTFIRE fire simulation model and provides an example application demonstrating the use of the models in performing fire and evacuation analysis for a large passenger ship partially based on the requirements of MSC circular 1033. The fire simulations include the action of a water mist system.

Integrated fire and evacuation in maritime environments

When designing a new passenger ship or modifying an existing design, how do we ensure that the proposed design and crew emergency procedures are safe from an evacuation resulting from fire or other incident? In the wake of major maritime disasters such as the Scandinavian Star, Herald of Free Enterprise, Estonia and in light of the growth in the numbers of high density high-speed ferries and large capacity cruise ships, issues concerning the evacuation of passengers and crew at sea are receiving renewed interest. Fire and evacuation models with features such as the ability to realistically simulate the spread of fire and fire suppression systems and the human response to fire sas well as the capability to model human performance in heeled orientations linked to a virtual reality environment that produces realistic visualisations of modelled scenarios are now available and can be used to aid the engineer in assessing ship design and procedures. This paper describes the maritmeEXODUS ship evacuation and the SMARTFIRE fire simulation model and provides an example application demonstrating the use of the models in performing fire and evacuation analysis for a large passenger ship partially based on the requirements of MSC circular 1033. The fire simulations include the action of a water mist system.

Advanced evacuation simulation software and its use in warships

The newly formed Escape and Evacuation Naval Authority regulates the provision of abandonment equipment and procedures for all Ministry of Defence Vessels. As such, it assures that access routes on board are evaluated early in the design process to maximize their efficiency and to eliminate, as far as possible, any congestion that might occur during escape. This analysis can be undertaken using a computer-based simulation for given escape scenarios and replicates the layout of the vessel and the interactions between each individual and the ship structure. One such software tool that facilitates this type of analysis is maritimeEXODUS. This tool, through large scale testing and validation, emulates human shipboard behaviour during emergency scenarios; however it is largely based around the behaviour of civilian passengers and fixtures and fittings of merchant vessels. Hence there existed a clear requirement to understand the behaviour of well-trained naval personnel as opposed to civilian passengers and be able to model the fixtures and fittings that are exclusive to warships, thus allowing improvements to both maritimeEXODUS and other software products. Human factor trials using the Royal Navy training facilities at Whale Island, Portsmouth were recently undertaken to collect data that improves our understanding of the aforementioned differences. It is hoped that this data will form the basis of a long-term improvement package that will provide global validation of these simulation tools and assist in the development of specific Escape and Evacuation standards for warships. © 2005: Royal Institution of Naval Architects.

The Medway Valley: a Kent landscape transformed

In 1750 the lower Medway Valley, the area between the towns of Maidstone and Rochester, was firmly part of Kent's 'Garden of England'. A century later, this tranquil, agrarian landscape had been transformed into a hive of industry and commerce, through the emergence of papermaking, cement manufacture, brickmaking, brewing, ship and barge building, seed crushing and engineering. The lower Medway Valley became synonymous with the production of Portland cement, stock bricks and the steam engines of Aveling and Porter, yet, by the end of the Second World War, much of this industry was gone. "The Medway Valley: A Kent Landscape Transformed", the first Victoria County History publication in Kent for over 75 years, charts this cyclical story of landscape change. It explores how the quiet, rural landscape of a collection of eight riverside parishes around Rochester was dramatically transformed during industrialization, before returning to its formal rural state. This volume traces the impact of industrial development and decline on the valley and its people. It details changing patterns of work and society, the creation of new settlements and the pivotal role of the river in all aspects of village life reflecting two centuries of change and upheaval.

Optimising vessel layout using human factors simulation

Evaluating ship layout for human factors (HF) issues using simulation software such as maritimeEXODUS can be a long and complex process. The analysis requires the identification of relevant evaluation scenarios; encompassing evacuation and normal operations; the development of appropriate measures which can be used to gauge the performance of crew and vessel and finally; the interpretation of considerable simulation data. In this paper we present a systematic and transparent methodology for assessing the HF performance of ship design which is both discriminating and diagnostic.

Reality-experiential history documentaries: the Trench (BBC, 2002) and Britain's modern memory of the First World War

Culloden (BBC, 1964) The Great War (BBC, 1964) 1914-18 (BBC/KCET, 1996) Haig: the Unknown Soldier (BBC, 1996) Veterans: the Last Survivors of the Great War (BBC, 1998) 1900s House (Channel 4, 1999) The Western Front (BBC, 1999) History of Britain (BBC, 2000) 1940s House (Channel 4, 2001) The Ship (BBC, 2002) Surviving the Iron Age (BBC, 2001) The Trench (BBC, 2002) Frontier House (Channel 4, 2002) Lad's Army (BBC, 2002) Edwardian Country House (Channel 4, 2002) Spitfire Ace (Channel 4, 2003) World War One in Colour (Channel 5, 2003) 1914: the War Revolution (BBC, 2003) The First World War (Channel 4, 2003) Dunkirk (BBC, 2004) Dunkirk: The Soldier's Story (BBC, 2004) D-Day to Berlin (BBC, 2004) Bad Lad's Army (ITV, 2004) Destination D-Day: Raw Recruits (BBC, 2004) Bomber Crew (Channel 4, 2004) Battlefield Britain (BBC, 2004) The Last Battle (ARTE/ZDF, 2005) Who Do You Think You Are? (BBC, 2004, 2006) The Somme (Channel 4, 2005) [From the Publisher]

Wave height analysis from 10 years of observations in the Norwegian Sea

Large waves pose risks to ships, offshore structures, coastal infrastructure and ecosystems. This paper analyses 10 years of in-situ measurements of significant wave height (Hs) and maximum wave height (Hmax) from the ocean weather ship Polarfront in the Norwegian Sea. During the period 2000 to 2009, surface elevation was recorded every 0.59 s during sampling periods of 30 min. The Hmax observations scale linearly with Hs on average. A widely-used empirical Weibull distribution is found to estimate average values of Hmax/H s and Hmax better than a Rayleigh distribution, but tends to underestimate both for all but the smallest waves. In this paper we propose a modified Rayleigh distribution which compensates for the heterogeneity of the observed dataset: the distribution is fitted to the whole dataset and improves the estimate of the largest waves. Over the 10-year period, the Weibull distribution approximates the observed Hs and Hmax well, and an exponential function can be used to predict the probability distribution function of the ratio Hmax/Hs. However, the Weibull distribution tends to underestimate the occurrence of extremely large values of Hs and Hmax. The persistence of Hs and Hmax in winter is also examined. Wave fields with Hs > 12 m and Hmax > 16 m do not last longer than 3 h. Low-to-moderate wave heights that persist for more than 12 h dominate the relationship of the wave field with the winter NAO index over 2000–2009. In contrast, the inter-annual variability of wave fields with Hs > 5.5 m or Hmax > 8.5 m and wave fields persisting over ~2.5 days is not associated with the winter NAO index.