56 research outputs found

    Demonstrating the feasibility of standardized application program interfaces that will allow mobile/portable terminals to receive services combining UMTS and DVB-T

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    Crucial to the commercial exploitation of any service combining UMTS and DVB-T is the availability of standardized API’s adapted to the hybrid UMTS and DVB-T network and to the technical limitations of mobile/portable terminals. This paper describes work carried out in the European Commission Framework Program 5 (FP5) project CONFLUENT to demonstrate the feasibility of such Application Program Interfaces (API’s) by enabling the reception of a Multimedia Home Platform (MHP) based application transmitted over DVB-T on five different terminals with parts of the service running on a mobile phone

    The climate of a retrograde rotating Earth

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    To enhance understanding of Earth's climate, numerical experiments are performed contrasting a retrograde and prograde rotating Earth using the Max Planck Institute Earth system model. The experiments show that the sense of rotation has relatively little impact on the globally and zonally averaged energy budgets but leads to large shifts in continental climates, patterns of precipitation, and regions of deep water formation.Changes in the zonal asymmetries of the continental climates are expected given ideas developed more than a hundred years ago. Unexpected was, however, the switch in the character of the European–African climate with that of the Americas, with a drying of the former and a greening of the latter. Also unexpected was a shift in the storm track activity from the oceans to the land in the Northern Hemisphere. The different patterns of storms and changes in the direction of the trades influence fresh water transport, which may underpin the change of the role of the North Atlantic and the Pacific in terms of deep water formation, overturning and northward oceanic heat transport. These changes greatly influence northern hemispheric climate and atmospheric heat transport by eddies in ways that appear energetically consistent with a southward shift of the zonally and annually averaged tropical rain bands. Differences between the zonally averaged energy budget and the rain band shifts leave the door open, however, for an important role for stationary eddies in determining the position of tropical rains. Changes in ocean biogeochemistry largely follow shifts in ocean circulation, but the emergence of a super oxygen minimum zone in the Indian Ocean is not expected. The upwelling of phosphate-enriched and nitrate-depleted water provokes a dominance of cyanobacteria over bulk phytoplankton over vast areas – a phenomenon not observed in the prograde model.What would the climate of Earth look like if it would rotate in the reversed (retrograde) direction? Which of the characteristic climate patterns in the ocean, atmosphere, or land that are observed in a present-day climate are the result of the direction of Earth's rotation? Is, for example, the structure of the oceanic meridional overturning circulation (MOC) a consequence of the interplay of basin location and rotation direction? In experiments with the Max Planck Institute Earth system model (MPI-ESM), we investigate the effects of a retrograde rotation in all aspects of the climate system.The expected consequences of a retrograde rotation are reversals of the zonal wind and ocean circulation patterns. These changes are associated with major shifts in the temperature and precipitation patterns. For example, the temperature gradient between Europe and eastern Siberia is reversed, and the Sahara greens, while large parts of the Americas become deserts. Interestingly, the Intertropical Convergence Zone (ITCZ) shifts southward and the modeled double ITCZ in the Pacific changes to a single ITCZ, a result of zonal asymmetries in the structure of the tropical circulation.One of the most prominent non-trivial effects of a retrograde rotation is a collapse of the Atlantic MOC, while a strong overturning cell emerges in the Pacific. This clearly shows that the position of the MOC is not controlled by the sizes of the basins or by mountain chains splitting the continents in unequal runoff basins but by the location of the basins relative to the dominant wind directions. As a consequence of the changes in the ocean circulation, a super oxygen minimum zone develops in the Indian Ocean leading to upwelling of phosphate-enriched and nitrate-depleted water. These conditions provoke a dominance of cyanobacteria over bulk phytoplankton over vast areas, a phenomenon not observed in the prograde model.</p

    Protein kinase C and cardiac dysfunction: a review

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    Heart failure (HF) is a physiological state in which cardiac output is insufficient to meet the needs of the body. It is a clinical syndrome characterized by impaired ability of the left ventricle to either fill or eject blood efficiently. HF is a disease of multiple aetiologies leading to progressive cardiac dysfunction and it is the leading cause of deaths in both developed and developing countries. HF is responsible for about 73,000 deaths in the UK each year. In the USA, HF affects 5.8 million people and 550,000 new cases are diagnosed annually. Cardiac remodelling (CD), which plays an important role in pathogenesis of HF, is viewed as stress response to an index event such as myocardial ischaemia or imposition of mechanical load leading to a series of structural and functional changes in the viable myocardium. Protein kinase C (PKC) isozymes are a family of serine/threonine kinases. PKC is a central enzyme in the regulation of growth, hypertrophy, and mediators of signal transduction pathways. In response to circulating hormones, activation of PKC triggers a multitude of intracellular events influencing multiple physiological processes in the heart, including heart rate, contraction, and relaxation. Recent research implicates PKC activation in the pathophysiology of a number of cardiovascular disease states. Few reports are available that examine PKC in normal and diseased human hearts. This review describes the structure, functions, and distribution of PKCs in the healthy and diseased heart with emphasis on the human heart and, also importantly, their regulation in heart failure

    How well can land-surface models represent the diurnal cycle of turbulent heat fluxes?

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    The diurnal cycle of solar radiation represents the strongest energetic forcing and dominates the exchange of heat and mass of the land surface with the atmosphere. This diurnal heat redistribution represents a core of land– atmosphere coupling that should be accurately represented in land surface models (LSMs), which are critical parts of weather and climate models. We employ a diagnostic model evaluation approach using a signature-based metric that describes the diurnal variation of heat fluxes. The metric is obtained by decomposing the diurnal variation of surface heat fluxes into their direct response and the phase lag to incoming solar radiation. We employ the output of 13 different LSMs driven with meteorological forcing of 20 FLUXNET sites (PLUMBER dataset). All LSMs show a poor representation of the evaporative fraction and thus the diurnal magnitude of the sensible and latent heat flux under cloud-free conditions. In addition, we find that the diurnal phase of both heat fluxes is poorly represented. The best performing model only reproduces 33% of the evaluated evaporative conditions across the sites. The poor performance of the diurnal cycle of turbulent heat exchange appears to be linked to how models solve for the surface energy balance and redistribute heat into the subsurface. We conclude that a systematic evaluation of diurnal signatures is likely to help to improve the simulated diurnal cycle, better represent land–atmosphere interactions, and therefore improve simulations of the near-surface climate. © 2020 American Meteorological Society
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